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1

Doppler flowmeter  

Energy Technology Data Exchange (ETDEWEB)

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

Karplus, Henry H. B. (Hinsdale, IL); Raptis, Apostolos C. (Downers Grove, IL)

1983-01-01

2

High speed nozzle flowmeter using miniaturized laser-Doppler techniques  

Energy Technology Data Exchange (ETDEWEB)

The application of modern optical techniques to meter calibration and real time measurement of large flowrates is outlined. The basic system consists of a converging device (nozzle) and a miniaturized laser Doppler system integrated inside the wall of a short duct section. Optical access to the flow by means of glass windows is not required anymore. This progress has been made possible by a new technique using two separated semiconductor lasers and signal demodulation. The flowmeter is designed for on-line measurement of flowrates up to 6000 m{sup 3}/h with an uncertainty of 1,2%...0,3%. This is due to the fact that the centre line velocity at the nozzle exit in the set-up is an excellent measure of the flowrate. For increasing accuracy an additional reference sensor to measure the whole boundary profile while leaving the sensor fixed can be installed optionally. The optical flowmeter can also be adapted to the well established use of orifice plates, but with the disadvantage of increased acquisition time.

Strunck, V.; Krey, E.A.; Mueller, K.H.; Dopheide, D. [Laboratory for Fluid Flow Measuring Techniques, Braunschweig (Germany)

1995-12-31

3

Two new types of laser doppler flowmeters prototypes validation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A fluxometria laser Doppler (LDF) é uma técnica para avaliação em tempo real do fluxo microcirculatório em tecidos biológicos. Esta técnica pode ser usada para monitorização não invasiva da microcirculação (por exemplo, avaliação da perfusão na pele), ou para monitorização da perfusão de forma invas...

Campos, Rita Helena Pinto Oliveira

4

Evaluation of blood flow in human rectal tumours using a laser Doppler flowmeter.  

Science.gov (United States)

A TSI laser Doppler flowmeter was used via a rigid sigmoidoscope in 20 consecutive patients with rectal carcinoma. Blood flow and velocity was evaluated at the tumour centre, tumour edge and adjacent normal mucosa; blood flow in the centre of the tumour was significantly higher than in normal mucosa (P = 0.05) and the tumour edge (P = 0.037). Two patients with ulcerated lesions had much lower blood flow in the centre of the ulcerative lesion. PMID:2253795

Zografos, G C; Iftikhar, S Y; Harrison, J; Morris, D L

1990-12-01

5

Evaluation of blood flow in human rectal tumours using a laser Doppler flowmeter.  

UK PubMed Central (United Kingdom)

A TSI laser Doppler flowmeter was used via a rigid sigmoidoscope in 20 consecutive patients with rectal carcinoma. Blood flow and velocity was evaluated at the tumour centre, tumour edge and adjacent normal mucosa; blood flow in the centre of the tumour was significantly higher than in normal mucosa (P = 0.05) and the tumour edge (P = 0.037). Two patients with ulcerated lesions had much lower blood flow in the centre of the ulcerative lesion.

Zografos GC; Iftikhar SY; Harrison J; Morris DL

1990-12-01

6

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

International Nuclear Information System (INIS)

[en] 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 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)

2008-01-01

7

Pancreatic capillary blood flow during caerulein-induced pancreatitis evaluated by a laser-doppler flowmeter in rats  

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 (p<0.05) and serum amylase (p<0.05) when compared to control and caerulein groups. Although micro and microvacuolization were seen in 30% in caerulein group, no significant difference was seen between the groups. CONCLUSION: A decrease in the PCBF may be one of the leading events and it is present before histopathological tissue injury had been established in this model of acute pancreatitis.

Meirelles Jr. Roberto Ferreira; Ceneviva Reginaldo  ; Caboclo José Liberato Ferreira; Eisenberg Michael M.

2003-01-01

8

A Doppler flowmeter for use in theatre.  

UK PubMed Central (United Kingdom)

We have developed a Doppler flowmeter based on a 10 MHz pencil probe and mean frequency estimator which overcomes many of the limitations of existing electromagnetic and ultrasonic flowmeters. The output of the flowmeter, which is proportional to the first moment of the Doppler power spectrum and hence mean blood velocity is linear from 1.3 to over 50 cm s-1 for pulsatile flow. Variation in vessel diameter and angle of insonation, which are the common sources of error in Doppler flowmetry, are minimised by constraining the vessel in a plastic cuff which fixes the probe angle at 50 degrees. A simple gauge is used to compress the vessel flat, before the cuff is applied, to measure the wall thickness to within 0.25 mm. The vessel internal diameter and hence blood flow can then be calculated using an experimentally determined calibration factor to compensate for non-even insonation. A range of sterilizable cuffs from 3-12 mm diameter have been built and the flowmeter is now being used routinely during all arterial reconstructive surgery. The accuracy and reproducibility of the system was tested for range of different sized silastic tubes on a hydraulic model and found to be less than 12% for vessels greater than 2 mm internal diameter. Satisfactory signals were easily obtained from all prosthetic materials with the exception of PTFE. The instantaneous output was compared to an electromagnetic flowmeter using a fast Fourier transform algorithm; the moduli of the harmonics were virtually identical but the Doppler system produced a smaller phase shift with increasing harmonics.(ABSTRACT TRUNCATED AT 250 WORDS)

Beard JD; Evans JM; Skidmore R; Horrocks M

1986-11-01

9

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  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese OBJETIVO: 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 estu (more) do 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 Abstract in english 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 (more) ± 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 (p

Meirelles Jr., Roberto Ferreira; Ceneviva, Reginaldo  ; Caboclo, José Liberato Ferreira; Eisenberg, Michael M.

2003-01-01

10

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.; Reginaldo Ceneviva; José Liberato Ferreira Caboclo; Michael M. Eisenberg

2003-01-01

11

Laser Doppler Velocimetry.  

Science.gov (United States)

Because it uses light scattering, Doppler shift, and optical heterodyne, laser Doppler velocimetry is an extremely powerful diagnostic technique for the measurement of flow velocity components. Its basic principles, optical arrangements, signal processing...

C. P. Wang

1986-01-01

12

The laser Doppler techniques  

Energy Technology Data Exchange (ETDEWEB)

An attempt is made to give a complete discussion of the principles of velocity measurement by the laser Doppler technique and an adequate description of the instruments and their application. The principles of laser optics are discussed and attention is given to the Doppler shift, the differential Doppler technique, signal processing techniques, directional discrimination and frequency shifting, and the properties of scattering properties. Such applications as studies of turbulence, the measurement of wind speed, and studies of combustion are discussed.

Drain, L.E.

1980-01-01

13

Imaging laser Doppler velocimetry  

Science.gov (United States)

Imaging laser Doppler velocimetry (ILDV) is a novel flow measurement technique, which enables the measurement of the velocity in an imaging plane. It is an evolution of heterodyne Doppler global velocimetry (HDGV) and may be regarded as the planar extension of the classical dual-beam laser Doppler velocimetry (LDV) by crossing light sheets in the flow instead of focused laser beams. Seeding particles within the flow are illuminated from two different directions, and the light scattered from the moving particles exhibits a frequency shift due to the Doppler effect. The frequency shift depends on the direction of the illumination and the velocity of the particle. The superposition of the two different frequency-shifted signals on the detector creates interference and leads to an amplitude modulated signal wherein the modulation frequency depends on the velocity of the particle. This signal is detected using either a high-speed camera or alternatively a smart pixel imaging array. This detector array performs a quadrature detection on each pixel with a maximum demodulation frequency of 250 kHz. To demonstrate the feasibility of the technique, two experiments are presented: The first experiment compares the measured velocity distribution of a free jet using ILDV performed with the smart pixel detector array and a high-speed camera with a reference measurement using PIV. The second experiment shows an advanced setup using two smart pixel detector arrays to measure the velocity distribution on a rotating disk, demonstrating the potential of the technique for high-velocity flow measurements.

Meier, Alexander H.; Roesgen, Thomas

2012-04-01

14

Holographic laser Doppler ophthalmoscopy  

CERN Multimedia

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

15

Evaluation of the use of an integration-type laser-Doppler flowmeter with a temperature-loading instrument for measuring skin blood flow in elderly subjects during cooling load: comparison with younger subjects.  

UK PubMed Central (United Kingdom)

An integration-type laser-Doppler flowmeter, equipped with a temperature-load instrument, for measuring skin blood flow (ILD-T), and analytical parameters developed in a previous study were used to compare changes in the skin blood flow in the forehead and cheek in elderly subjects (in their 60s and 70s) with those in younger subjects (in their teens to 50s). Age-related differences in skin blood flow in the forehead and cheek in response to cooling were evaluated in 90 healthy women in their teens to 70s (mean age: 17.2 +/- 0.33 years for teenagers; 24.3 +/- 0.76 years for those aged 20-29 years; 34.8 +/- 1.12 years for those aged 30-39 years; 43.3 +/- 0.78 years for those aged 40-49 years; 53.8 +/- 1.13 years for those aged 50-59 years; 63.5 +/- 0.55 years for those aged 60-69 years; 72.2 +/- 0.70 years for those aged 70-79 years). The measurement was performed continuously for 5 min: for 1 min at a sensor temperature of 30 degrees C, for 2 min after the setting of the sensor temperature had been changed to 10 degrees C, and for 2 min after the temperature setting had been cancelled. The parameters analyzed were (1) skin temperature in a resting state before measurement ( T(rest)), (2) mean skin blood flow in 1 min at a sensor temperature of 30 degrees C ( F(30 degrees C)), (3) minimum skin blood flow at a sensor temperature of 10 degrees C ( F(min)), (4) slope of the blood flow plot during the period from the beginning of cooling at 10 degrees C to F(min) ( S(fall)), (5) time required for the sensor temperature to reach 10 degrees C (Delta t(s)), (6) maximum skin blood flow during the period from the end of cooling to the end of measurement ( F(max)), (7) slope of the blood flow plot during the period from F(min) to F(max) ( S(rise)), (8) rate of decrease of the skin blood flow during cooling: FDR = ( F(min)/ F(30 degrees C))x100, (9) recovery rate of the skin blood flow after the end of cooling: FRR = ( F(max)/ F(30 degrees C))x100. When correlations among the above nine parameters were evaluated by combining all age groups, significant correlations ( P < 0.01) were observed between F(30 degrees C) and F(min), F(30 degrees C) and F(max), F(30 degrees C) and S(fall), F(min) and F(max), and F(max) and S(rise) in the forehead. In the cheek, significant correlations ( P < 0.01) were observed in all these combinations except between F(max) and S(rise). When these analytical parameters were compared among the age groups, F(30 degrees C), T(rest), F(max), and S(rise) decreased significantly ( P < 0.02 for F(30 degrees C) and T(rest), P < 0.01 for F(max) and S(rise)) and S(fall) increased significantly ( P < 0.03) in the forehead with aging. However, no significant change with aging was observed in FDR, Delta t(s), F(min), and FRR. In the cheek, FDR increased significantly ( P < 0.03), and S(rise) decreased significantly ( P < 0.01) with aging. However, no significant change with aging was observed in F(30 degrees C), T(rest), F(max), S(fall), Delta t(s), F(min), and FRR. Thus, the decrease in the skin blood flow during cooling showed no marked quantitative change with age, but, with aging, the rate of this decrease was clearly reduced in the forehead. In the cheek, on the other hand, the skin blood flow decreased markedly with aging, but no clear change was observed in the rate of this decrease. By using ILD-T and examining various parameters obtained, the skin hemodynamics in the forehead and cheek during cooling from 30 degrees C to 10 degrees C could be analyzed, and differences in the hemodynamics between the forehead and cheek and between elderly and younger individuals were clarified. This instrument is expected to be clinically useful.

Nagashima Y; Yada Y; Suzuki T; Sakai A

2003-05-01

16

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)

2008-01-01

17

Laser Doppler flowmetry: an aid in differential diagnosis of apical radiolucencies.  

UK PubMed Central (United Kingdom)

The case of a patient having 2 teeth with associated apical radiolucencies that responded to conventional pulp tests is presented. A decision was made to reexamine the patient at intervals rather than perform root canal treatment. During a recall visit, use of an available laser Doppler flowmeter allowed detection of blood flow within the affected teeth. A diagnosis of periapical cemental dysplasia (cementoma) was made.

Chandler NP; Love RM; Sundqvist G

1999-05-01

18

Signal validation in laser-Doppler velocimetry  

International Nuclear Information System (INIS)

[en] Simple models are applied to gain insight into signal validation in laser-Doppler velocimetry and its effects on transit-time broadening. The predictions obtained are compared with measurements of decaying turbulence behind a grid using two techniques. Turbulence levels down to 0.04 percent were measured, a tenfold improvement over previously reported laser-Doppler measurements. 11 references

1988-01-01

19

Simultaneous assessment of cardiac output with pulsed Doppler and electromagnetic flowmeters during cardiac stimulation.  

UK PubMed Central (United Kingdom)

The aim of this study was to test the accuracy of cardiac output assessment by Doppler and electromagnetic flowmetry in dogs during states of (1) marked enhancement in cardiac output, which was obtained by means of either isoprenaline infusion or treadmill exercise, or (2) reduction in cardiac output obtained by administration of phenylephrine. Additionally, in vitro comparisons were undertaken between Doppler and electromagnetic flow-probes and assessment of flow by direct volumetric measurement. These in vitro experiments showed a good correlation between timed volume collections and electromagnetic flow assessment up to high flow velocities. Doppler flow measurements underestimated the flow at high velocities. In both the resting dog and after phenylephrine, that is, at states with low heart rate and cardiac output, the waveforms of electromagnetic flow and Doppler velocity were similar for both phasic and mean flow, respectively. During states of cardiac stimulation Doppler flow showed a decrease in maximum velocity in the ascending aorta. Due to this decrease in peak flow velocity, mean Doppler blood flow did not increase despite of increased heart rate. This result cannot be explained on the basis of the deviation of Doppler measurements at high velocities in the in vitro experiments. Although our results are in contradiction with earlier studies, electromagnetic assessment seems to be more reliable in blood flow measurements in the ascending aorta. Hence, Doppler flow measurements should not be used uncritically for such quantitative flow assessment in large vessels as determination of cardiac output.

Grohs JG; Huber S; Raberger G

1993-09-01

20

Simultaneous assessment of cardiac output with pulsed Doppler and electromagnetic flowmeters during cardiac stimulation.  

Science.gov (United States)

The aim of this study was to test the accuracy of cardiac output assessment by Doppler and electromagnetic flowmetry in dogs during states of (1) marked enhancement in cardiac output, which was obtained by means of either isoprenaline infusion or treadmill exercise, or (2) reduction in cardiac output obtained by administration of phenylephrine. Additionally, in vitro comparisons were undertaken between Doppler and electromagnetic flow-probes and assessment of flow by direct volumetric measurement. These in vitro experiments showed a good correlation between timed volume collections and electromagnetic flow assessment up to high flow velocities. Doppler flow measurements underestimated the flow at high velocities. In both the resting dog and after phenylephrine, that is, at states with low heart rate and cardiac output, the waveforms of electromagnetic flow and Doppler velocity were similar for both phasic and mean flow, respectively. During states of cardiac stimulation Doppler flow showed a decrease in maximum velocity in the ascending aorta. Due to this decrease in peak flow velocity, mean Doppler blood flow did not increase despite of increased heart rate. This result cannot be explained on the basis of the deviation of Doppler measurements at high velocities in the in vitro experiments. Although our results are in contradiction with earlier studies, electromagnetic assessment seems to be more reliable in blood flow measurements in the ascending aorta. Hence, Doppler flow measurements should not be used uncritically for such quantitative flow assessment in large vessels as determination of cardiac output. PMID:8241544

Grohs, J G; Huber, S; Raberger, G

1993-09-01

 
 
 
 
21

Local regulation of blood flow evaluated simultaneously by 133-xenon washout and laser Doppler flowmetry  

International Nuclear Information System (INIS)

The laser Doppler flowmeter and the 133-Xenon washout techniques of measuring cutaneous blood flow were compared for measuring the vasoconstrictor response of the hand during orthostatic maneuvres. Important discrepancies were detected for the two methods. When the hand was lowered by 40 cm a 40% decrease in blood flow was detected by the 133-Xenon method, while a 60% decrease was seen by the laser Doppler technique. Lowering the hand by 50 cm resulted in no further blood flow decrease when using the 133-Xenon method, but an 80% blood flow decrease was recorded with the laser Doppler method. A marked decrease in blood flow was recorded by the laser Doppler technique in hands that were sympathectomized or a hand that was subjected to a nerve blockade, strategies which should eliminate the orthostatic vasoconstrictor response of superficial cutaneous vessels. The 133-Xenon technique did not detect any blood flow changes in hands without sympathetic tone. We found the laser Doppler flowmetry technique unsatisfactory for measurement of blood flow changes that occur in nutritional vessels as this method measures total skin blood flow including non-capillary vessels.

1988-01-01

22

Nonorthogonal Measurement Axes in Laser Doppler Velocimetry.  

Science.gov (United States)

The measurement axes of virtually all multiaxis laser Doppler velocimeter (LDV) systems are nonorthogonal to some degree and are, in general, rotated with respect to orthogonal, Cartesian reference axes. Systematic errors are introduced into the LDV data ...

F. L. Crosswy

1979-01-01

23

Research on the Laser Doppler Torque Sensor  

International Nuclear Information System (INIS)

Based on laser Doppler effect, single section rotational speed of a rotating shaft was measured. By measuring the two sections rotational speed, the difference of the rotational speed between the two could be made. Integrating the rotational speed difference, the relative torsional angle of the two sections under the action of torsional virbration was received, so the rotating shaft torque was gotten. Non-contact torque measurement of rotary machine was achieved. The system was designed and the experiment was done on the torque experiment equipment. The result of experimentation indicate that the relative error between Laser Doppler and conventional torque measuring method that was less than 0.2%, and the measurement accuracy of Laser Doppler was high.

2006-01-01

24

Signal-to-noise improvement in laser Doppler velocimetry.  

UK PubMed Central (United Kingdom)

Simple optical methods are described that, working in conjunction with an electronic synchronous detector, can substantially increase signal detectability in laser Doppler velocimetry. These methods involve rotating the laser polarization to amplitude-modulate exclusively the Doppler signal.

Le-Cong P; Lovberg RH

1980-12-01

25

Developments in laser Doppler blood perfusion monitoring  

Digital Repository Infrastructure Vision for European Research (DRIVER)

peer-reviewed , This paper reviews the development and use of laser Doppler perfusion monitors and imagers. Despite their great success and almost universal applicability in microcirculation research, they have had great difficulty in converting to widespread clinical application. The enormous interest...

Leahy, Martin J.; de Mul, Frits F.M.; Nilsson, Gert E.; Maniewski, Roman; Liebert, Adam

26

Laser Doppler Velocimeter particle velocity measurement system  

Energy Technology Data Exchange (ETDEWEB)

This report gives a detailed description of the operation of the Laser Doppler Velocimeter (LDV) system maintained by DIAL at MSU. LDV is used for the measurement of flow velocities and turbulence levels in various fluid flow settings. Ills report details the operation and maintenance of the LDV system and provides a first-time user with pertinent information regarding the system`s setup for a particular application. Particular attention has been given to the use of the Doppler signal analyzer (DSA) and the burst spectrum analyzer (BSA) signal processors and data analysis.

Wilson, W.W.; Srikantaiah, D.V.; Philip, T.; George, A.

1993-10-01

27

Series of calibration tests at national standard loops and industrial application experiences of new type flow-metering system by ultrasonic pulse-doppler profile-velocimetry  

International Nuclear Information System (INIS)

Highly-accurate measurements are required to control the thermal outputs for reactor feedwater flow rates. Calibration tests for flowmeters such as time-of-flight (TOF) ultrasonic flow meters are conducted to assure their accuracy in measurements at standard loops, where flow profile factors, which adjust measurand to real flow rates, are determined usually by conducting calibration tests under ambient flow conditions. As nuclear power plants are aging, readings of flowmeters for reactor feedwater systems drift due to the changes of flow profiles. The causes of those deviations are affected by the change of wall roughness of inner surface of pipings, and those changes of flow patterns lead to large errors in measurements. Therefore, it is still in suspicion if its high accuracy on adjusting measurand by profile factors is traceable against the national standard, and moreover, we have to consider the difference of flow configuration between the flow standard and measurement position on-site. The difference of facilities for measurement conditions can be considered as the concept of 'Facility Factor' and the 'Profile Factor' is not sufficient for correcting the meter reading. It is so discussed that measurement of velocity profile on-site is essential. We proposed the new type of flowmeter called UdFlow/UDF, ultrasonic pulse-Doppler flowmeter, which can measure instantaneously-determined flow-velocity profiles and eliminate the effect of deviated flow profile from expected ideal one. Series of calibration tests of UdFlow were conducted at the national standard loops in Mexico, CENAM (The Centro National de Metrologia) and in USA, NIST (National Institute of Standard and Technology) in order to evaluate the accuracy of the flowmeter. Four ultrasonic transducers are mounted on the surface of stainless steel piping circumferentially with the diameters of 100mm and 200mm to measure four velocity profiles. The calibration tests found a deviation better than 0.3% between the two devices in terms of the average of the values recorded by six rounds of each measurement. From the results of measurement conducted with Reynolds number varied, it was found that the overall average deviation between the two devices was better than 0.3%. (author)

2008-01-01

28

Considerations for Calibrating a Laser Doppler Anemometer  

Energy Technology Data Exchange (ETDEWEB)

Laser Doppler Anemometers have long been the device-of-choice for air velocity measurements due to their avoidance of turbulence induced by insertion-method air velocity measurement devices. At first glance, the use of a Laser Doppler Anemometer (LDA) for calibrating air velocity meters appears to be a relatively simple and straightforward process. As is typical in most metrological applications the process becomes much more complex when attempting to use the apparatus to make high-performance, metrology measurements. This paper focuses on the considerations for calibration of a LDA beginning with a discussion why an LDA needs to be calibrated. Other areas of discussion include alignment of the optics, dealing with imperfections in the alignment process, establishing the traceability of measurements from the apparatus and design and development of and experiences with using a calibration apparatus.

Duncan, Michael L [ORNL; Keck, Joe [ORNL

2010-01-01

29

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.

1983-01-01

30

Laser Doppler Velocimetry Using Diode Lasers.  

Science.gov (United States)

The development of very small velocimeters for biomedical and industrial applications with emphasis on instrumentation and theory for skin blood flow measurements is addressed. Characteristics of the diode lasers used in the velocimeters are presented and...

H. W. Jentink

1989-01-01

31

Measurement depth and volume in laser Doppler flowmetry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Fredriksson, Ingemar; Larsson, Marcus; Strömberg, Tomas

32

A laser Doppler method for noninvasive measurement of flow velocity  

Energy Technology Data Exchange (ETDEWEB)

Laser Doppler velocimetry is a powerful optical technique for noninvasively obtaining experimental flow-velocity data. This paper describes the principle of operation and various optical configurations of the laser Doppler velocimeter. As a sample application, we describe an experimental apparatus for measuring the velocity flow field around a cylinder, and give our experimental results.

Biggs, G.L.

1986-11-25

33

Direct comparison of laser Doppler flowmetry and laser Doppler imaging for assessment of experimentally-induced inflammation in human skin  

DEFF Research Database (Denmark)

Laser Doppler imaging (LDI) and laser Doppler flowmetry (LDF) can measure localized skin perfusion. The purpose of the study was to directly compare LDF with LDI as a tool for measuring skin blood changes in an experimental model of chemically-induced skin inflammation.

Petersen, Lars J

2013-01-01

34

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

35

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

36

USAGE OF LASER DOPPLER FLOWMETRY FOR CHILDREN BLOOD MICROCIRCULATION ASSESSMENT  

Directory of Open Access Journals (Sweden)

Full Text Available The individual features of blood microcirculation were investigated for children of 6-9 years. The childrennormative of blood microcirculation were revealed due to laser Doppler flow data.

Anosov I. P.; Antonovskaya L. V.; Gornaya O. I.; Stanishevskaya T. I.; Mankovskaya L. N.; Yusupova O.V.; Khomatov V. X.

2011-01-01

37

Measurement of Water Flowing Velocity Using Laser Doppler Velocimetry Technique  

International Nuclear Information System (INIS)

[en] A Doppler laser differential method was used to measure the velocity of water flowing in a transparent glass tube in two cases : 1) a tap water and 2) a water pumped by a fish tank pump, the water had been colored with potassium permanganate (KMnO4). Several measurements of the water velocity were carried out manually and with Doppler laser differential method for both cases. The comparison between these measurements shows a reasonable agreement. (Authors)

2005-01-01

38

Reference beam laser Doppler velocimeter incorporating fiber optic components  

Energy Technology Data Exchange (ETDEWEB)

A compact reference beam laser Doppler velocimeter, constructed using a semiconductor laser diode, optical fiber components and semiconductor detectors, is reported. The device has been designed to overcome many of the problems commonly associated with reference beam configurations. The anemometer may be operated with the laser diode operating in cw and pulsed modes, demonstrating its applicability to wavelength and time division multiplexing schemes for 3D laser Doppler velocimetry. The probe is used to measure the velocity of a spinning disk in the range {minus}20 m/s to +20 m/s.

James, S.W.; Lockey, R.A.; Egan, D.; Tatam, R.P. [Cranfield Univ., Bedford (United Kingdom)

1995-12-31

39

Image-based tracking laser Doppler vibrometer  

International Nuclear Information System (INIS)

An innovative version of the tracking laser Doppler vibrometer based on image acquisition and processing (iTLDV) is proposed. The iTLDV is developed for tracking of arbitrary motions; the system is feedback controlled and allows measuring the vibrations of a moving target by driving moving mirrors via position signals of the target obtained from a charge-coupled-device camera and an image processing algorithm. The tracking system developed has been applied to an industrial test case subject to self-excited vibrations, in order to verify the performances and limits in the operating conditions. The system demonstrates its ability to measure vibration time histories on a windscreen wiper in operative conditions. This test case represents a challenging measurement problem, since no other measurement techniques are available that are able to extract such data. Some examples of obtained data are shown, which highlight the potential of iTLDV. In addition, position accuracy and measurement uncertainty are discussed. For the windscreen wiper, the worst position accuracy is estimate as ±1.2 mm along the wiper axis, while the measurement uncertainty mainly depends on the commercial vibrometer applied in the setup (about ±2% depending on operative conditions)

2004-01-01

40

Muscle activity characterization by laser Doppler Myography  

Science.gov (United States)

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.

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

2013-09-01

 
 
 
 
41

Laser Doppler velocimetry based on the optoacoustic effect in a RF-excited CO2 laser  

International Nuclear Information System (INIS)

[en] We present a compact optoacoustic laser Doppler velocimetry method that utilizes the self-mixing effect in a RF-excited CO2 laser. A portion of a Doppler-shifted laser beam, produced by irradiating a single wavelength laser beam on a moving object, is mixed with an originally existing laser beam inside a laser cavity. The fine change of pressure in the laser cavity modulated by the Doppler-shifted frequency is detected by a condenser microphone in the laser tube. In our studies, the frequency of the Doppler signal due to the optoacoustic effect was detected as high as 50 kHz. Our measurements also confirmed that the signal varied linearly with the velocity of the external scatterer (the moving object) and the cosine of the angle between the laser beam and the velocity vector of the object.

2012-01-01

42

Laser Doppler velocimetry based on the optoacoustic effect in a RF-excited CO2 laser  

Science.gov (United States)

We present a compact optoacoustic laser Doppler velocimetry method that utilizes the self-mixing effect in a RF-excited CO2 laser. A portion of a Doppler-shifted laser beam, produced by irradiating a single wavelength laser beam on a moving object, is mixed with an originally existing laser beam inside a laser cavity. The fine change of pressure in the laser cavity modulated by the Doppler-shifted frequency is detected by a condenser microphone in the laser tube. In our studies, the frequency of the Doppler signal due to the optoacoustic effect was detected as high as 50 kHz. Our measurements also confirmed that the signal varied linearly with the velocity of the external scatterer (the moving object) and the cosine of the angle between the laser beam and the velocity vector of the object.

Lee, Teaghee; Choi, Jong Woon; Kim, Yong Pyung

2012-09-01

43

Laser Doppler velocimetry and fluorescein dye in the prediction of skin flap viability. A comparison.  

UK PubMed Central (United Kingdom)

Laser Doppler velocimetry provides a quantitative and noninvasive measurement of cutaneous blood flow. Piglets were used to compare laser Doppler velocimetry and fluorescein with each other and as predictors of flap viability. Twenty-five random pattern rectangular skin flaps were studied with both techniques. Eighteen of the flaps were observed for two weeks and the length of viable flap documented. A reading of 100 mV on the laser Doppler corresponded with full fluorescence after dye injection. Both fluorescein and the laser Doppler underestimated flap surviving length slightly. Laser Doppler readings taken 24 hours postoperatively predicted the length of surviving flap exactly. The laser Doppler correlated well with fluorescein dye.

Larrabee WF Jr; Sutton GD; Holloway A Jr; Tolentino G

1983-07-01

44

Doppler flowmetry as a tool of predictive, preventive and personalised dentistry.  

UK PubMed Central (United Kingdom)

Periodontal lesions are considered a major problem in the global burden of oral diseases due to their high frequency and negative impact on quality of life. Periodontal inflammation is accomplished by a breakdown of microcirculatory function. Early detection of gingival microvessel dysfunction helps diagnose and prevent the progression of initial periodontal pathology. Doppler flowmetry is a useful tool in the diagnosis, monitoring, prognosis and management of periodontal patients which allows access not only of gingival blood flow but also of pulpal microcirculation. Doppler flowmeters might help to realise the ultimate target of predictive, preventive and personalised periodontology tailored with respect to the particular patient. This article highlights the main working principles of laser Doppler flowmeters and the ultrasonic Doppler flowmeters. The advances in blood flow measurement by ultrasonic flowmetry are discussed.

Orekhova LY; Barmasheva AA

2013-08-01

45

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; Dželetovi? Bojan; Živkovi? Slavoljub; Kršljak Elena

2010-01-01

46

Ultrahigh sensitivity laser Doppler velocimetry with a microchip solid-state laser.  

UK PubMed Central (United Kingdom)

Highly sensitive laser Doppler velocimetry featuring the simultaneous measurement of light-scattering objects moving at different velocities and vibration sensing based on Doppler-shifted light-injectioninduced intensity modulation in an externally pumped microchip solid-state laser is demonstrated.

Otsuka K

1994-02-01

47

Validation of scanning laser Doppler flowmetry for retinal blood flow measurements in animal models.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate the validity of scanning laser Doppler flowmetry in retinal blood flow measurement in vivo using rabbit and monkey eyes and the microsphere technique. METHODS: A commercially available scanning laser Doppler flowmeter (SLDF), pigmented rabbits and cynomolgus monkeys were used. In rabbits, SLDF measurements at a retinal field approximately one papillary diameter away from the optic nerve head where discrete retinal vessels were not visible (vascularized medullary field) were compared with those at a field approximately one papillary diameter below the ONH (nonvascularized extramedullary field). The effect of intraocular pressure (IOP) on SLDF measurements was studied by elevating the IOP manometrically in both rabbit and monkey eyes. Retinal and choroidal blood flow measurements using the microsphere technique and an SLDF measurements were performed simultaneously in the same rabbit eye before and 30 min after 0.3 mg/kg intravenous injection of lomerizine, a calcium antagonist, or intravitreal injection of 20 microl of 10(-6) M endothelin-1. RESULTS: The blood flow measurement with an SLDF (SLDF flow) obtained from the medullary field in rabbits were 304 +/- 63 in an arbitrary unit (n = 24), while 392 +/- 39 in the extramedullary field. SLDF flow did not significantly changed by changes in IOP when it was below 50 mmHg, significantly decreasing with IOP elevation above that level in rabbits and a similar tendency was also seen in monkeys. It showed a significant correlation with retinal blood flow measured by the microsphere technique (r = 0.596, P < 0.0001) in rabbits; no correlation was found with the choroidal blood flow rate (r = 0.021, P > 0.1). CONCLUSIONS: SLDF measurements is thought to mainly reflect retinal circulation in rabbits and monkeys.

Tamaki Y; Araie M; Fukaya Y; Ishi K

2002-05-01

48

Video flowmeter  

Science.gov (United States)

A video flowmeter is described that is capable of specifying flow nature and pattern and, at the same time, the quantitative value of the rate of volumetric flow. An image of a determinable volumetric region within a fluid containing entrained particles is formed and positioned by a rod optic lens assembly on the raster area of a low-light level television camera. The particles are illuminated by light transmitted through a bundle of glass fibers surrounding the rod optic lens assembly. Only particle images having speeds on the raster area below the raster line scanning speed may be used to form a video picture which is displayed on a video screen. The flowmeter is calibrated so that the locus of positions of origin of the video picture gives a determination of the volumetric flow rate of the fluid. 4 figs.

Lord, D.E.; Carter, G.W.; Petrini, R.R.

1983-08-02

49

Video flowmeter  

Energy Technology Data Exchange (ETDEWEB)

A video flowmeter is described that is capable of specifying flow nature and pattern and, at the same time, the quantitative value of the rate of volumetric flow. An image of a determinable volumetric region within a fluid (10) containing entrained particles (12) is formed and positioned by a rod optic lens assembly (31) on the raster area of a low-light level television camera (20). The particles (12) are illuminated by light transmitted through a bundle of glass fibers (32) surrounding the rod optic lens assembly (31). Only particle images having speeds on the raster area below the raster line scanning speed may be used to form a video picture which is displayed on a video screen (40). The flowmeter is calibrated so that the locus of positions of origin of the video picture gives a determination of the volumetric flow rate of the fluid (10).

Lord, David E. (Livermore, CA); Carter, Gary W. (Livermore, CA); Petrini, Richard R. (Livermore, CA)

1983-01-01

50

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

Energy Technology Data Exchange (ETDEWEB)

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.

Krogh-Soerensen, K.; Lunde, O.C. (Aker University Hospital, Oslo (Norway))

1993-02-01

51

Translational and Brownian motion in laser-Doppler flowmetry of large tissue volumes.  

Science.gov (United States)

This study reports the derivation of a precise mathematical relationship existing between the different p-moments of the power spectrum of the photoelectric current, obtained from a laser-Doppler flowmeter (LDF), and the red blood cell speed. The main purpose is that both the Brownian (defining the 'biological zero') and the translational movements are taken into account, clarifying in this way what the exact contribution of each parameter is to the LDF derived signals. The derivation of the equations is based on the quasi-elastic scattering theory and holds for multiple scattering (i.e. measurements in large tissue volumes and/or very high red blood cell concentration). The paper also discusses why experimentally there exists a range in which the relationship between the first moment of the power spectrum and the average red blood cells speed may be considered as 'linear' and what are the physiological determinants that can result in nonlinearity. A correct way to subtract the biological zero from the LDF data is also proposed. The findings should help in the design of improved LDF instruments and in the interpretation of experimental data. PMID:15724535

Binzoni, T; Leung, T S; Seghier, M L; Delpy, D T

2004-12-21

52

Translational and Brownian motion in laser-Doppler flowmetry of large tissue volumes  

International Nuclear Information System (INIS)

[en] This study reports the derivation of a precise mathematical relationship existing between the different p-moments of the power spectrum of the photoelectric current, obtained from a laser-Doppler flowmeter (LDF), and the red blood cell speed. The main purpose is that both the Brownian (defining the 'biological zero') and the translational movements are taken into account, clarifying in this way what the exact contribution of each parameter is to the LDF derived signals. The derivation of the equations is based on the quasi-elastic scattering theory and holds for multiple scattering (i.e. measurements in large tissue volumes and/or very high red blood cell concentration). The paper also discusses why experimentally there exists a range in which the relationship between the first moment of the power spectrum and the average red blood cells speed may be considered as 'linear' and what are the physiological determinants that can result in nonlinearity. A correct way to subtract the biological zero from the LDF data is also proposed. The findings should help in the design of improved LDF instruments and in the interpretation of experimental data

2004-12-21

53

Laser Doppler velocimetry based on the photoacoustic effect in a CO2 laser  

International Nuclear Information System (INIS)

[en] We report a simple laser Doppler velocimeter in which the photoacoustic effect was used to measure the rotation wheel speed. A Doppler signal, caused by mixing a returning wave with an originally existing wave inside the CO2 laser cavity, was detected using a microphone in the laser tube. Frequency of the microphone output was in proportion to the rotation speed of a wheel and is dependent on the cosine of the angle between the direction of the laser beam and tangent of wheel velocity. A Doppler-shifted frequency as high as 34 kHz was detected using this method. A frequency response of a few megahertz is expected from the laser Doppler velocimeter based on the photoacoustic effect in a CO2 laser by using a wider bandwidth microphone

2005-01-01

54

Dual beam translator for use in Laser Doppler anemometry  

Energy Technology Data Exchange (ETDEWEB)

A method and apparatus for selectively translating the path of at least one pair of light beams in a Laser Doppler anemometry device whereby the light paths are translated in a direction parallel to the original beam paths so as to enable attainment of spacial coincidence of the two intersection volumes and permit accurate measurements of Reynolds shear stress.

Brudnoy, David M. (Albany, NY)

1987-01-01

55

Dual beam translator for use in Laser Doppler anemometry  

Energy Technology Data Exchange (ETDEWEB)

A method and apparatus for selectively translating the path of at least one pair of light beams in a Laser Doppler anemometry device whereby the light paths are translated in a direction parallel to the original beam paths so as to enable attainment of spacial coincidence of the two intersection volumes and permit accurate measurements of Reynolds shear stress.

Brudnoy, D.M.

1984-04-12

56

Methodology and reproducibility of bidirectional laser Doppler velocimetry  

International Nuclear Information System (INIS)

[en] Bidirectional laser Doppler velocimetry in conjunction with monochromatic fundus photography allows non invasive measurement of retinal blood velocity. We have shown that it gives reproducible results in humans and experimental animals which agree well with those of the radioactively labelled microsphere technique. (author)

1990-01-01

57

Laser doppler velocimetry of the retinal blood flow.  

UK PubMed Central (United Kingdom)

The principles of laser doppler velocimetry, as applied to the measurement of retinal blood flow, are described. The technique offers the possibility of non-invasive clinical measurement; either continuous sequential measurements or repeated intermittent estimates can be made. The field of application is outlined.

Hill DW; Pike ER; Gardner K

1981-01-01

58

Power spectra of fluid velocities measured by laser Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

The power spectrum and the correlation of the laser Doppler velocimeter velocity signal obtained by sampling and holding the velocity at each new Doppler burst are studied. Theory valid for low fluctuation intensity flows shows that the measured spectrum is filtered at the mean sample rate and that it contains a filtered white noise spectrum caused by the steps in the sample and hold signal. In the limit of high data density, the step noise vanishes and the sample and hold signal is statistically unbiased for any turbulence intensity.

Adrian, R.J.; Yao, C.S.

1987-01-01

59

Clinical use of laser Doppler flowmetry in a burns unit.  

UK PubMed Central (United Kingdom)

Laser Doppler Flowmetry (LDF) is a new noninvasive technique by which microcirculation changes in tissue can be studied. This has been done in a Burns Unit on burned as well as non-burned patients (volunteers). There were no infection problems with this device in a Burns Unit. Four kHz was the upper wave length limit analysing the doppler signal from burns. A topical temperature load test was defined and used in different situations. Homogeneous flows in reference points from a control group were demonstrated in unheated and heated skin, in this way standardizing the LDF analyses of skin microflow. Ability of LDF to define different degrees of burns was demonstrated.

Micheels J; Alsbjörn B; Sørensen B

1984-01-01

60

Laser Doppler velocimetry: a new technique for the measurement of intestinal mucosal blood flow.  

UK PubMed Central (United Kingdom)

Laser Doppler velocimetry is a technique for continuous measurement of blood flow changes in tissue utilizing the Doppler shift principle. The authors describe a study designed to evaluate laser Doppler velocimetry measurement of blood flow in the canine small intestinal mucosa compared with electromagnetically measured total flow to the isolated segment of the intestine.

Feld AD; Fondacaro JD; Holloway GA Jr; Jacobson ED

1984-08-01

 
 
 
 
61

Fabrication of Portable Laser Doppler Velocimetry and Speckle Velocimetry  

Energy Technology Data Exchange (ETDEWEB)

The laser power stability and laser frequency stability of various liquid lasers and gas lasers were affected by the fluid velocity of a laser active medium. The control of laser cavities in order to reduced the fluctuation of laser powers have been studied. However, inspit of these methods, the power instability of the multi-step dye laser system for high power was 5-10 %. The main reason was the flow instabilities of laser active madium. Then we have been studied the measurement of fluid velocities and velocity distributions of the dye fluid in a dye cell by using a ready-made laser Doppler velocimeter(LDV), which is a good sensor for the measurement of fluid velocities with high accuracy. However, the ready-made LDV has a several disadvantages of big sizes, large optical probes, high prices, difficulties of the moving, etc.. In this study, we have studies for the fabrication of small potable LDV with small optical probes using a high power DRB laser diode and single mode optical fibers for the measurement of fluid velocities from 1 cm/s to 1 m/s. 28 refs., 1 tabs., 53 figs. (author)

Jo, Jae Hong; Chang, S.; Kim, B. J.; Lee, J. C.; Choi, W. H.; Kim, J. T. [Hannam University, Taejon (Korea, Republic of)

1997-07-01

62

Novel Doppler laser radar for diagnostics in fusion reactors  

International Nuclear Information System (INIS)

We describe the development of a novel Doppler laser radar (DOLAR) for remote measurement of flow velocity (0-10 m/s) and film thickness of liquid metal walls, currently being studied for their superior heat handling and self-healing characteristics. Small fluctuations in flow velocity(?mm/s) and flow thickness (?50 ?m) that may arise during plasma discharges can also be measured. The DOLAR is also designed for non intrusive mapping of features of plasma-facing solid surfaces with very high precision (?50 ?m). It can also measure the motion of structural components of a fusion reactor during plasma discharges and during plasma disruptions. The device utilizes frequency modulation laser radar principles for precision range measurements. Compensation of Doppler frequency shift is used to measure flow velocity. The DOLAR probe head is designed with acousto-optic and piezoelectric devices for operation in the harsh fusion environment.

2004-01-01

63

Evaluation of a bronchial anastomosis by laser Doppler velocimetry.  

UK PubMed Central (United Kingdom)

Healing after bronchoplasty was evaluated by assessing the bronchial mucosal blood flow by laser Doppler velocimetry in dogs. Bronchoplastic surgery at the right main bronchus was performed and bronchial mucosal blood flow was determined by laser Doppler velocimetry at proximal and distal sides of the anastomosis before and after operation. Four experimental groups were established. After operation the blood flow was adequately preserved, and healing of the anastomosis site was satisfactory in the minimum detachment group and steroid-treated group. Mucosal blood flow was markedly reduced in both proximal and distal sides in the extensive detachment group. The extent of the reduction in the blood flow was smaller in the omentum dressing group than in the extensive detachment group. The state of healing of the anastomosis site was closely related to the bronchial mucosal blood flow.

Inui K; Wada H; Yokomise H; Lee M; Yamazaki F; Aoki M; Hitomi S

1990-04-01

64

Laser Doppler echo signal detection method  

Science.gov (United States)

The coherent lidar system for speed measurement and the characteristics of the echo signal are discussed. And the principle and the advantages of the digital quadrature transform are analyzed. A digital quadrature detection scheme based on polyphase filter for coherent lidar system for speed measurement is presented by using the idea of software radio. Firstly the amplified analog signal is sampled to digital signal, and then is re-sampled with parity, time-aligned by delay filtering, finally the signal is divided into in-phase component and quadrature component. The scheme can be used to decrease the hardware complexity of system to a large extent, to avoid aliasing between the positive and the negative spectrums, to improve the SNR, and to obtain the signal in the quadrature form so as to fit the follow-up processing. Simulations and experiments indicate that the scheme is capable of resisting the noise compared with the traditional methods and is prone to real-time implementation, which, in turn, makes a contribution to greatly improve the performance of coherent Doppler lidar system for speed measurement and to orient the direction of a moving target.

Wang, Jiqiang; Zhang, Chunxi; Feng, Di; Ou, Pan; Tian, Lun

2009-05-01

65

Laser-scanning Doppler photoacoustic microscopy based on temporal correlation.  

UK PubMed Central (United Kingdom)

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 W; Liu W; Zhang HF

2013-05-01

66

New concept for laser Doppler vibrometry of the human ear  

Science.gov (United States)

While several technical problems could be solved and the reproducibility of the technique appeared to be high enough, the individual variations between different persons seems to limit the importance of using laser Doppler vibrometry for clinical diagnosis. The complexity of the motions of the middle ear bones with frequency dependent superpositions of translational and rotational modes is seen as chance for a yield of information about middle ear diseases. A new concept is presented which relays on two laser beams guided under different angle onto the same spot to determine between the different kinds of motions. The theoretical and basis and first experimental tests are described to evaluate the reliability of this concept.

Foth, Hans-Jochen; Kretner, Ralf

1998-04-01

67

Dynamic fringe broadening in multiple line laser Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

The recently reported multiple line laser Doppler velocimetry technique involves a compromise between laser power and fringe broadening. The present work analyzes the broadening as a function of both the target velocity and the separations of the Fabry-Perot etalons, which in this work do not have to be the same. It is shown that the overlap finesse broadening, which is defined as the ratio of the frequency separation between fringes to the overlap broadening, depends on the number of free spectral ranges that have occurred due to the velocity of the reflecting target.

Goosman, D.R. (Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (US))

1990-01-01

68

Clinical use of laser Doppler flowmetry in a burns unit.  

Science.gov (United States)

Laser Doppler Flowmetry (LDF) is a new noninvasive technique by which microcirculation changes in tissue can be studied. This has been done in a Burns Unit on burned as well as non-burned patients (volunteers). There were no infection problems with this device in a Burns Unit. Four kHz was the upper wave length limit analysing the doppler signal from burns. A topical temperature load test was defined and used in different situations. Homogeneous flows in reference points from a control group were demonstrated in unheated and heated skin, in this way standardizing the LDF analyses of skin microflow. Ability of LDF to define different degrees of burns was demonstrated. PMID:6234654

Micheels, J; Alsbjörn, B; Sørensen, B

1984-01-01

69

Mucosal blood flow measurements using laser Doppler perfusion monitoring  

Directory of Open Access Journals (Sweden)

Full Text Available Perfusion of individual tissues is a basic physiological process that is necessary to sustain oxygenation and nutrition at a cellular level. Ischemia, or the insufficiency of perfusion, is a common mechanism for tissue death or degeneration, and at a lower threshold, a mechanism for the generation of sensory signalling including pain. It is of considerable interest to study perfusion of peripheral abdominal tissues in a variety of circumstances. Microvascular disease of the abdominal organs has been implicated in the pathogenesis of a variety of disorders, including peptic ulcer disease, inflammatory bowel disease and chest pain. The basic principle of laser Doppler perfusion monitoring (LDPM) is to analyze changes in the spectrum of light reflected from tissues as a response to a beam of monochromatic laser light emitted. It reflects the total local microcirculatory blood perfusion, including perfusion in capillaries, arterioles, venules and shunts. During the last 20-25 years, numerous studies have been performed in different parts of the gastrointestinal (GI) tract using LDPM. In recent years we have developed a multi-modal catheter device which includes a laser Doppler probe, with the intent primarily to investigate patients suffering from functional chest pain of presumed oesophageal origin. Preliminary studies show the feasibility of incorporating LDPM into such catheters for performing physiological studies in the GI tract. LDPM has emerged as a research and clinical tool in preference to other methods; but, it is important to be aware of its limitations and account for them when reporting results.

Dag Arne Lihaug Hoff, Hans Gregersen, Jan Gunnar Hatlebakk

2009-01-01

70

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-09-15

71

Which parameter is better to define endothelial dysfunction in a test of postocclusive hyperemia measured by laser-Doppler flowmetry?  

UK PubMed Central (United Kingdom)

BACKGROUND AND OBJECTIVE: Endothelial function can be measured by the level of reactive vasodilation due to a transient ischemia caused by a blood pressure cuff on the arm, measured using Laser-Doppler flowmetry. This device has software that provides various parameters that can measure the magnitude of this response, but there are no general agreements with regard to which of them is the best to use. In this study, we analyze which of the parameters obtained using this technique is better to discriminate between patients with coronary artery disease (CAD) and healthy controls. METHODS: We analyzed 40 patients with proven CAD and 60 healthy controls. We studied the hyperemic response to the ischemia in the forearm using a Laser-Doppler flowmeter. RESULTS: The most important differences between patients and controls were determined considering the area of hyperemia, which was 2.6 times higher in healthy controls than that in patients (754.9±566.4 vs 1981.3±1156.3 perfusion units per second, P<0.001). To diagnose the disease, a cutoff point of 860 perfusion units per second had a sensitivity of 0.82 and a specificity of 0.97. This is probably because the area of hyperemia measures at the same time speed, intensity, and duration of the hyperemic response. CONCLUSION: The area of hyperemia was the parameter with a higher sensitivity and specificity for identification of patients with CAD. Nevertheless, further studies are needed to confirm the usefulness of this parameter, obtained using a noninvasive test, to assess the presence of subclinical coronary heart disease.

Stiefel P; Moreno-Luna R; Vallejo-Vaz AJ; Beltrán LM; Costa A; Gómez L; Ordóñez A; Villar J

2012-01-01

72

Estimation of laser-Doppler anemometry measuring volume displacement in cylindrical pipe flow  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Laser-Doppler anemometry application in measurements of the 3-D swirl turbulent flow velocity in the cylindrical pipe, behind the axial fan, have been analysed. This paper presents a brief overview of uncertainty sources in the laser-Doppler anemometry measurements. Special attention is paid to ...

Risti? Slavica S.; Ili? Jelena T.; ?antrak ?or?e S.; Risti? Ognjen R.; Jankovi? Novica Z.

73

Nonmechanical transverse scanning laser Doppler velocimeter using wavelength change.  

UK PubMed Central (United Kingdom)

A transverse scanning laser Doppler velocimeter (LDV) that does not require any moving mechanism in its sensor probe is proposed, and the scanning function is demonstrated theoretically and experimentally. In the proposed scanning LDV, the measurement position is transversely scanned on the basis of a wavelength change induced by a tunable laser and a combination of a grating and a Dove prism. To demonstrate the scanning function in the transverse direction, an experiment was carried out using a setup of the sensor probe consisting of bulk optical components. The experimental results indicate that a transverse scanning function was successfully obtained. The scanning range in the vertical direction is estimated to be 11.3 mm over wavelengths of 1520 to 1570 nm.

Maru K; Fujiwara T; Ikeuchi R

2011-11-01

74

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

75

Pulsatile poststenotic flow studies with laser Doppler anemometry.  

UK PubMed Central (United Kingdom)

The pulsatile flow field distal to axisymmetric constrictions in a straight tube was studied using laser Doppler anemometry. The upstream centerline velocity waveform was sinusoidal at a frequency parameter of 7.5 and mean Reynolds number of 600. Stenosis models of 25, 50 and 75% area reduction were employed and velocity data were derived by ensemble averaging methods. Extensive measurements of the pulsatile velocity profiles are reported, and wall shear rates were computed from the near wall velocity profile gradients. The experiments indicate that a permanent region of poststenotic flow separation does not exist even for the severest constriction, in contrast to results for steady flow. Values of wall shear stress were greatest near the throat of the constriction and were relatively low in the poststenotic region, including the region of most intense flow disturbance. Turbulence was found only for the 75% stenosis model and was created only during a segment of the cycle. Although much emphasis has been placed upon turbulence in the detection of arterial stenoses, particularly as identified by Doppler ultrasound spectral broadening, the present study implies that identification of flow disturbances of an organized nature may be more fundamental in recognizing mild to moderate disease. Additionally, the relationship of these flow field results to the animal aortic coarctation model often employed in atherogenesis studies is discussed.

Ahmed SA; Giddens DP

1984-01-01

76

Bragg cell laser intensity modulation: effect on laser Doppler velocimetry measurements.  

Science.gov (United States)

In most laser Doppler velocimetry (LDV) systems, the frequency of one of the two laser beams that intersect to create the probe volume is shifted with an acousto-optic element. It is shown here that Bragg shifting can impose a problematic fluctuation in intensity on the frequency-shifted beam, producing spurious velocity measurements. This fluctuation occurs at twice the Bragg cell frequency, and its relative amplitude to the time average intensity is a function of the ratio of the laser beam diameter to the Bragg cell acoustic wavelength. A physical model and a configuration procedure to minimize adverse effects of the intensity modulations are presented. PMID:19543356

Mychkovsky, Alexander G; Chang, Natasha A; Ceccio, Steven L

2009-06-20

77

Bragg cell laser intensity modulation: effect on laser Doppler velocimetry measurements  

Energy Technology Data Exchange (ETDEWEB)

In most laser Doppler velocimetry (LDV) systems, the frequency of one of the two laser beams that intersect to create the probe volume is shifted with an acousto-optic element. It is shown here that Bragg shifting can impose a problematic fluctuation in intensity on the frequency-shifted beam, producing spurious velocity measurements. This fluctuation occurs at twice the Bragg cell frequency, and its relative amplitude to the time average intensity is a function of the ratio of the laser beam diameter to the Bragg cell acoustic wavelength. A physical model and a configuration procedure to minimize adverse effects of the intensity modulations are presented.

Mychkovsky, Alexander G.; Chang, Natasha A.; Ceccio, Steven L.

2009-06-20

78

Bragg cell laser intensity modulation: effect on laser Doppler velocimetry measurements.  

UK PubMed Central (United Kingdom)

In most laser Doppler velocimetry (LDV) systems, the frequency of one of the two laser beams that intersect to create the probe volume is shifted with an acousto-optic element. It is shown here that Bragg shifting can impose a problematic fluctuation in intensity on the frequency-shifted beam, producing spurious velocity measurements. This fluctuation occurs at twice the Bragg cell frequency, and its relative amplitude to the time average intensity is a function of the ratio of the laser beam diameter to the Bragg cell acoustic wavelength. A physical model and a configuration procedure to minimize adverse effects of the intensity modulations are presented.

Mychkovsky AG; Chang NA; Ceccio SL

2009-06-01

79

Vocal fold vibration measurements using laser Doppler vibrometry.  

UK PubMed Central (United Kingdom)

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.

Chan A; Mongeau L; Kost K

2013-03-01

80

Measurements of enlarged blood pump models using Laser Doppler Anemometer.  

Science.gov (United States)

In an earlier study (Chua et al., 1998, 1999a), a 5:1 enlarged model of the Kyoto-NTN Magnetically Suspended Centrifugal Blood Pump (Akamatsu et al., 1995) with five different impeller blade profiles was designed and constructed. Their respective flow characteristics with respect to (1) the three different blade profile designs: forward, radial, and backward, (2) the number of blades used, and (3) the rotating speed were investigated. Among the five impeller designs, the results obtained suggested that impellers A and C designs should be adopted if higher head is required. Impellers A and C therefore were selected for the flow in between their blades to be measured using Laser Doppler Anemometer (LDA), so as to have a better understanding of the flow physics with respect to the design parameters. PMID:10999377

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

2000-01-01

 
 
 
 
81

Measurements of enlarged blood pump models using Laser Doppler Anemometer.  

UK PubMed Central (United Kingdom)

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

Chua LP; Yu SC; Leo HL

2000-01-01

82

Application of laser Doppler technology to meniscal injuries.  

Science.gov (United States)

It has been recognized for many years that the vascular supply to the meniscus has been extremely important in the potential for healing of a repaired meniscus. Early experimental work confirmed that meniscal defects that communicated with the peripheral vascular network would heal if repaired. However, those tears that did not communicate with the vascular bed would not heal even if repaired. Unfortunately, there has been no clinically applicable technique for evaluating blood flow in the torn meniscus. Experimental procedures using laser Doppler flowmetry have shown this to be a precise and simple tool for the evaluation of meniscal blood flow. Applications of this technique in the clinical situation show great promise in enabling the surgeon to make a decision to repair or remove the torn meniscus based on the blood flow in the remaining vascular bed. PMID:2406079

Limbird, T J

1990-03-01

83

Application of laser Doppler technology to meniscal injuries.  

UK PubMed Central (United Kingdom)

It has been recognized for many years that the vascular supply to the meniscus has been extremely important in the potential for healing of a repaired meniscus. Early experimental work confirmed that meniscal defects that communicated with the peripheral vascular network would heal if repaired. However, those tears that did not communicate with the vascular bed would not heal even if repaired. Unfortunately, there has been no clinically applicable technique for evaluating blood flow in the torn meniscus. Experimental procedures using laser Doppler flowmetry have shown this to be a precise and simple tool for the evaluation of meniscal blood flow. Applications of this technique in the clinical situation show great promise in enabling the surgeon to make a decision to repair or remove the torn meniscus based on the blood flow in the remaining vascular bed.

Limbird TJ

1990-03-01

84

Laser Doppler velocimetry measurements in valved and ported engines  

Energy Technology Data Exchange (ETDEWEB)

Measurements are presented of bulk velocity and its cyclic variation and of turbulence intensity in IC engines with combustion chambers of open shape. Engines with both ported and valved intakes were tested. The ported engine was tested both with and without swirl and the valved engine without swirl only. The ported engine was motored at 1200, 1800 and 2400 RPM and the valved engine at 600, 1200 and 1800 RPM. In both engines the shape of the combustion chamber was such as not to introduce strong organized gas motion during compression. Thus the in-cylinder gas motion, including turbulence, was due primarily to the intake process. The measurements were made using laser Doppler velocimetry as data rates which were sufficiently high to determine the bulk velocity in each cycle and thereby separate the cyclic fluctuations of the bulk velocity from the turbulence.

Liou, T.-M.; Hall, M.; Santavicca, D.A.; Bracco, F.V.

1984-01-01

85

Velocity bias in two component individual realization laser Doppler velocimetry  

International Nuclear Information System (INIS)

[en] In addition to the typical biasing problems associated with one component Laser Doppler Velocimetry (LDV), two component LDV measurements can suffer from other types of bias. In particular, coincidence bias is of interest. This type of velocity bias results from requiring simultaneous, or nearly simultaneous, measurements of the velocity components. In this study, two velocity bias correction schemes, based on the time between velocity samples, together with three different approaches for constant time-interval sampling of the velocity data have been evaluated. The effects of coincidence seeding rate and coincidence time window on velocity, normal, and Reynold's stress measurements are presented. Measurements with narrow coincidence window settings and/or low coincidence seeding rate resulted in velocity measurements which were larger than the true local average

1986-01-01

86

Short-time Fourier transform laser Doppler holography  

CERN Multimedia

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

87

Cantilever spring constant calibration using laser Doppler vibrometry  

International Nuclear Information System (INIS)

Uncertainty in cantilever spring constants is a critical issue in atomic force microscopy (AFM) force measurements. Though numerous methods exist for calibrating cantilever spring constants, the accuracy of these methods can be limited by both the physical models themselves as well as uncertainties in their experimental implementation. Here we report the results from two of the most common calibration methods, the thermal tune method and the Sader method. These were implemented on a standard AFM system as well as using laser Doppler vibrometry (LDV). Using LDV eliminates some uncertainties associated with optical lever detection on an AFM. It also offers considerably higher signal to noise deflection measurements. We find that AFM and LDV result in similar uncertainty in the calibrated spring constants, about 5%, using either the thermal tune or Sader methods provided that certain limitations of the methods and instrumentation are observed.

2007-01-01

88

Laser Doppler assessment of dermal circulatory changes in people with coronary artery disease.  

UK PubMed Central (United Kingdom)

BACKGROUND: Dermal microcirculation provides an easily accessible vasculature bed which can be used to assess endothelial mediated vasodilatation. We studied and compared microcirculatory changes in response to acetylcholine iontophoresis (ACh), local heating of the skin and reactive hyperaemia in patients with coronary artery disease (CAD). METHODS AND RESULTS: Forty eight patients with CAD were studied and compared with 25 age and sex matched control subjects. Vasodilatory changes in the dermal microcirculation were assessed in response to ACh iontophoresis, local heating of the skin and reactive hyperaemia using a laser Doppler flowmeter (LDF). RESULTS: Body mass index (BMI) and systolic BP were higher in people with CAD, (p=0.001, 0.043). The perfusion change (measured as absolute in agreement with our previous publish results) in response to ACh iontophoresis, local heating of the skin and reactive hyperaemia, in healthy controls was 234 (190-286), 90 (69-118), 139(106-172) arbitrary perfusion units (APU) compared to 161 (121-214), 50 (39-63), 116(77-143) APU in patients with CAD; p<0.03. The time to peak perfusion in response to reactive hyperaemia was significantly higher in patients with CAD, 14.1±4.0 vs 10.9±1.7s; p=0.001. There was a small but significant positive correlation between the perfusion change in response to ACh iontophoresis and local heating (r=0.31, p=0.035). On ROC curve analysis, perfusion changes with heating had higher sensitivity and specificity in discriminating patients with CAD from the healthy controls with an area under the curve (AUC) of 0.86, with a specificity of 92% and sensitivity of 77% compared to a perfusion changes by reactive hyperaemia, AUC of 0.68 (41% sensitivity and 91% specificity) and ACh iontophoresis, AUC of 0.76 (88% sensitivity and 60% specificity). CONCLUSION: Vasodilatation in the dermal microcirculation measured by the three techniques is attenuated in patients with coronary artery disease. Local heating of the skin is a better discriminator of patients with CAD than ACh iontophoresis and reactive hyperaemia.

Agarwal SC; Allen J; Murray A; Purcell IF

2012-07-01

89

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 (p<0.001). After 14 days for the Er:YAG area the blood perfusion returned to the initial value. The results in diode area remained at a high level after 14 days. Both lasers 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

90

Laser Doppler vibrometry with a single-frequency microchip green laser  

Science.gov (United States)

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.

Anto?czak, Arkadiusz J.; Kozio?, Pawe?; Sotor, Jaros?aw Z.; Kaczmarek, Pawe? R.; Abramski, Krzysztof M.

2011-11-01

91

Novel Applications of Laser Doppler Vibration Measurements to Medical Imaging  

Science.gov (United States)

Laser Doppler Vibrometry (LDV) has been widely used in engineering applications involving non-contact vibration and sound measurements. This technique has also been used in some biomedical applications including hearing research. The detectable frequencies are in the range of near-DC to 1 GHz or higher. This paper reviews applications of LDV in biomedical engineering and proposes new medical imaging applications based on measuring surface vibrations of tissues and organs. Tests were conducted on human skin using single point and scanning laser vibrometers. These tests suggest that skin vibrations due to the forcing excitation from the heart can be used in imaging of blood flow. The results of these tests illustrate the potential of such vibration measurements in a variety of diagnostic medical imaging applications including blood flow/restrictions, real-time monitoring of blood pressure variations, wound healing, muscle movements, etc. The fact that the measurements can be conducted remotely (non-contact) is an important benefit that adds to the promise of this approach.

Tabatabai, Habib; Oliver, David E.; Rohrbaugh, John W.; Papadopoulos, Christopher

2013-06-01

92

Preliminary experiences with laser Doppler velocimetry for the determination of amputation levels.  

UK PubMed Central (United Kingdom)

Laser Doppler velocimetry is a newly available technique for the continuous and non-invasive measurement of capillary perfusion. The technique is presented and preliminary results of its use in the evaluation of amputation levels in 16 patients discussed.

Holloway GA Jr; Burgess EM

1983-08-01

93

Estimation of laser-Doppler anemometry measuring volume displacement in cylindrical pipe flow  

Directory of Open Access Journals (Sweden)

Full Text Available Laser-Doppler anemometry application in measurements of the 3-D swirl turbulent flow velocity in the cylindrical pipe, behind the axial fan, have been analysed. This paper presents a brief overview of uncertainty sources in the laser-Doppler anemometry measurements. Special attention is paid to estimation of laser-Doppler anemometry measuring volume positioning in cylindrical pipe flow due to optical aberrations, caused by the pipe wall curvature. The hypothesis, that in the central part of the pipe (r/R < 0.6) exists a small, or negligible pipe wall influence on laser- -Doppler anemometry measuring position, is investigate. The required corrections, for measurements of axial, tangential, and radial velocity components such: shift of measuring volume and its orientation are analyzed and determined for used test rig and for some other pipe geometries. [Projekat Ministarstva nauke Republike Srbije, br. TR 35046

Risti? Slavica S.; Ili? Jelena T.; ?antrak ?or?e S.; Risti? Ognjen R.; Jankovi? Novica Z.

2012-01-01

94

Remote measurement of the transverse wind velocity component using a laser Doppler velocimeter.  

UK PubMed Central (United Kingdom)

The wind speed transverse to the line-of-sight of a laser Doppler radar has been measured using the intensity fluctuations of the returned signal. These measurements were made at a range of 100 m with a CO(2) cw laser Doppler velocimeter, which was simultaneously performing its design function of determining the radial velocity component. The transverse component measurements are compared with those obtained using a u, v, w Gill propeller anemometer.

Kennedy LZ; Bilbro JW

1979-09-01

95

Temperature load test to increase the accuracy of laser Doppler monitoring of flaps.  

Science.gov (United States)

A heat and cold provocation test was evaluated in 10 porcine island flaps to improve the quality of monitoring flap circulation by the laser Doppler technique. When the pedicle blood flow was undisturbed there were significant increases in flow after a heat stimulus (p = 0.01), whereas no significant flow changes were noted during arterial or venous occlusion. This method can increase the accuracy of the laser Doppler technique in monitoring the circulation in skin flaps. PMID:1626225

Hedén, P; Arnander, C

1992-01-01

96

Temperature load test to increase the accuracy of laser Doppler monitoring of flaps.  

UK PubMed Central (United Kingdom)

A heat and cold provocation test was evaluated in 10 porcine island flaps to improve the quality of monitoring flap circulation by the laser Doppler technique. When the pedicle blood flow was undisturbed there were significant increases in flow after a heat stimulus (p = 0.01), whereas no significant flow changes were noted during arterial or venous occlusion. This method can increase the accuracy of the laser Doppler technique in monitoring the circulation in skin flaps.

Hedén P; Arnander C

1992-01-01

97

Flow rates in turbo-couplings with constant filling level. Measurements using laser doppler velocimetry; Stroemungsgeschwindigkeit in konstantgefuellter Turbokupplung. Messung mittels Laser-Doppler-Velocimetrie  

Energy Technology Data Exchange (ETDEWEB)

Numeric calculations of flow processes in hydrodynamic transmission systems require experimental verification. The contribution describes flow processes in turbo-couplings in realistic operating and geometric conditions and discusses the potential and limits of laser doppler velocimetry. [German] Zur Verifizierung von numerischen Berechnungen der Stroemungsvorgaenge in hydrodynamischen Leistungsuebertragern sind experimentelle Untersuchungen erforderlich. Aus der Fachliteratur sind aber bisher nur Ergebnisse bekannt, die an speziellen Versuchskupplungen und unter bestimmten Laborbedingungen erzielt wurden. Die in dem Beitrag vorgestellten Untersuchungen geben einen interessanten Aufschluss ueber die Stroemungsvorgaenge in Turbokupplungen unter realen betrieblichen und geometrischen Bedingungen sowie ueber die Einsatzmoeglichkeiten und Grenzen des optischen Messverfahrens Laser-Doppler-Velocimetrie. (orig.)

Christen, M. [Technische Univ. Dresden (Germany). Fakultaet fuer Maschinenwesen; Kernchen, R. [Voith Turbo GmbH und Co. KG, Crailsheim (Germany)

2001-07-01

98

Laser-Doppler velocimetry, a contactless flow metering technique in energy engineering. Laser-Doppler-Velozimetrie als beruehrungsloses Stroemungsmessverfahren in der Energietechnik  

Energy Technology Data Exchange (ETDEWEB)

Laser Doppler velocimetry has been applied successfully for some time now as a scientific method for contactless velocity and volume flow measurement. In energy engineering, on the other hand it is rarely used as a routine technique in spite of its many technical advantages. The article analyzes the reasons for this lack of acceptance on the public utilities' side and presents solutions to the technical problems accompanying the industrial-scale application of this technique. The application of laser Doppler velocimetry is illustrated by examples of research projects closely related to energy engineering. The authors assume a break-through of this technique in the Nineties. (orig.).

Radke, M.; Siekmann, H.E.

1989-10-01

99

Doppler modulation and Zeeman modulation: laser frequency stabilization without direct frequency modulation.  

UK PubMed Central (United Kingdom)

We discuss two methods (Zeeman modulation and Doppler modulation) for locking the frequency of a singlemode cw laser to an atomic absorption line. These methods do not require the laser frequency to be modulated directly. In the first scheme the absorption frequency of the atom is modulated via the Zeeman effect; in the second scheme the laser frequency is modulated indirectly via the Doppler effect in an atomic beam. We used the two methods successfully to lock two dye lasers to the transitions 6S((1/2)) ? 7S((1/2)) and 7S((1/2)) ? 15P(?) in atomic cesium.

Weis A; Derler S

1988-07-01

100

Noninvasive determination of skin perfusion pressure using a laser Doppler.  

UK PubMed Central (United Kingdom)

Laser Doppler (LD) measures blood flow in approximately one cubic millimeter of tissue. The LD instrument is well suited to the determination of the initiation of flow in the microcirculation after a period of arrest due to externally applied counterpressure. Radioisotope clearance and photoplethysmography have been used to measure skin perfusion pressure (SPP) in an effort to predict healing of ischemic ulcerations and amputation wounds. By placing the LD probe beneath a blood pressure cuff, SPP was measured at the forearm, thigh, calf, foot, dorsal and plantar great toe. The SPP was measured in 32 normal limbs and 26 limbs with rest pain, ulceration or gangrene. Skin of normal extremities and forearm and thigh skin of patients with ischemic lower extremities had a mean SPP of 47 mmHg (+/- 5 SEM). The SPP in ischemic extremities was significantly lower at the calf 22 +/- 4 (p less than .001), the foot 10 +/- 2 (p less than .0001), and the toe 16 +/- 4 (p less than .0001). SPP was greater at the plantar toe (73 +/- 5) than in all other locations. Skin of the plantar toe was unique among the sites measured because it is rich in arteriovenous anastomoses, which have a thermoregulatory function. The higher pressure probably reflects the fact that the larger arterioles have a higher intraluminal pressure than the capillaries and, therefore, a more proximal level of the microcirculation is measured by the LD instrument in thermoregulatory areas of the skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Castronuovo JJ Jr; Pabst TS; Flanigan DP; Foster LG

1987-05-01

 
 
 
 
101

Noninvasive determination of skin perfusion pressure using a laser Doppler.  

Science.gov (United States)

Laser Doppler (LD) measures blood flow in approximately one cubic millimeter of tissue. The LD instrument is well suited to the determination of the initiation of flow in the microcirculation after a period of arrest due to externally applied counterpressure. Radioisotope clearance and photoplethysmography have been used to measure skin perfusion pressure (SPP) in an effort to predict healing of ischemic ulcerations and amputation wounds. By placing the LD probe beneath a blood pressure cuff, SPP was measured at the forearm, thigh, calf, foot, dorsal and plantar great toe. The SPP was measured in 32 normal limbs and 26 limbs with rest pain, ulceration or gangrene. Skin of normal extremities and forearm and thigh skin of patients with ischemic lower extremities had a mean SPP of 47 mmHg (+/- 5 SEM). The SPP in ischemic extremities was significantly lower at the calf 22 +/- 4 (p less than .001), the foot 10 +/- 2 (p less than .0001), and the toe 16 +/- 4 (p less than .0001). SPP was greater at the plantar toe (73 +/- 5) than in all other locations. Skin of the plantar toe was unique among the sites measured because it is rich in arteriovenous anastomoses, which have a thermoregulatory function. The higher pressure probably reflects the fact that the larger arterioles have a higher intraluminal pressure than the capillaries and, therefore, a more proximal level of the microcirculation is measured by the LD instrument in thermoregulatory areas of the skin.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3584224

Castronuovo, J J; Pabst, T S; Flanigan, D P; Foster, L G

102

Laser doppler velocimetry measurements in valved and ported engines  

Energy Technology Data Exchange (ETDEWEB)

Measurements are presented of bulk velocity and its cyclic variation and of turbulence intensity in IC engines with combustion chambers of open shape. Engines with both ported* and valved intakes were tested. The ported engine was tested both with and without swirl and the valved engine without swirl only. The ported engine was motored at 1200, 1800 and 2400 RPM and the valved engine at 600, 1200 and 1800 RPM. In both engines the shape of the combustion chamber was such as not to introduce strong organized gas motion during compression. Thus the in-cylinder gas motion, including turbulence, was due primarily to the intake process. The measurements were made using laser Doppler velocimetry at data rates which were sufficiently high to determine the bulk velocity in each cycle and thereby separate the cyclic fluctuations of the bulk velocity from the turbulence. Such measurements are called cycleresolved and have not previously been made in either valved or ported engines at practical engine speeds using LDV. The measurements were made at numerous spatial locations in the ported engine and at a single location in the valved engine, in both cases on a plane centered within the clearance height over a crankangle interval of sixty-four degrees around TDC.

Liou, T.M.; Bracco, F.V.; Hall, M.; Santavicca, D.A.

1984-02-01

103

Correlation between fluorescein flowmetry and laser Doppler flowmetry  

International Nuclear Information System (INIS)

A study was undertaken to compare two new methods of capillary blood flow measurement, namely fluorescein flowmetry (FF) and laser Doppler flowmetry (LDF). The blood flow was measured in a pelvis pouch during its construction and in the completed ileoanal anastomosis in 12 patients. There was a high correlation between the two methods when the blood flow was measured in the pelvic pouch. The correlation coefficient between the two methods for the difference between the blood flow in the pelvic pouch at the site of the planned anastomosis when the pouch resided in the abdomen and that in the completed ileoanal anastomosis was r=0.99, the reduction amounted to 25% as measured by FF and 27% as measured by LDF. All ileoanal anastomoses healed perfectly, the lowest FF and LDF values being 0.004 density units/s and 0.3 V, respectively. The results indicate that either method can be considered for measuring capillary blood flow. 8 refs., 2 figs

1990-01-01

104

Laser doppler flowmetry evaluation as a pulpal vitality test; Avaliacao da fluxometria laser doppler como teste de vitalidade pulpar  

Energy Technology Data Exchange (ETDEWEB)

The more frequently used pulp vitality tests (PVTs) are the thermal (cold and heat) and the electrical stimulus. These tests are, however, subjective, depending on the sensitivity threshold of each individual, and usually fail when immature or recently traumatised teeth are tested. The laser Doppler flowmetry (LDF) have been suggested as a PVT, by evaluating the pulp measured flow (F). The measured quantity F, used to discriminate healthy and non-vital teeth, is sensitive to factors hardly controlled or predictable, such as the LDFs and probe response differences, and the flow variations among individuals. It was suggested recently a new discriminator, F(%), less sensitive to such factors. The PVTs performances for F (%) and F as discriminators, however, were not known. The present study aimed to evaluate the PVTs' performances using the quantities F(%) and F (dif) as discriminators, both derived from F, and to compare, qualitatively and quantitatively, their performances to that obtained by using F. The quantities F(%) and F(dif) are, respectively, the ratio and the difference of the flow from the interrogated tooth and its healthy homologous, being F(dif) a proposed new discriminator. The obtained confidence intervals (95% of significance) of the areas under ROC curves were from 0,964 to 1,000 for F (%); from 0,959 to 1,000 for F (dif) and; from 0,584 to 0,951 for F; showing that F(%) and F (dif) are more reliable discriminators then F. (author)

Eduardo, Flavia Tavares de Oliveira de Paula

2004-07-01

105

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

106

Observation of sub-Doppler Laser Induced Nuclear Orientation of 85mRb  

International Nuclear Information System (INIS)

This paper reports on the first observation of sub-Doppler resolved gamma anisotropy produced by Laser Induced Nuclear Orientation (LINO). The anisotropy was produced by laser optical pumping the Dl transition of the 1?s 85mRb isomer. Sub-Doppler LINO is uniquely suited for resolving closely spaced hyperfine structure (hfs) of very shortlived isomers, whose lifetimes are between 50 nanoseconds and 1 milli-second. In addition, sub-Doppler LINO allows more precise measurements of hf splittings to be made. For example, this leads to more accurate measurements of nuclear magnetic dipole and electric quadrupole moments, as well as isomer shifts. LINO uses laser optical pumping to produce electronic alignment. This is transferred to the excited nucleus via the hyperfine interaction. When the oriented nuclei decay, anisotropy is observed in the spatial distribution of the emitted gamma rays. The hfs of the isomer is determined by monitoring the anisotropy as a function of laser detuning

1989-01-01

107

Effect of tooth isolation on laser Doppler readings.  

UK PubMed Central (United Kingdom)

AIM: To measure differences between single (STI) and multiple teeth isolation (MTI), pulpal blood flow (PBF) was assessed using laser Doppler flowmetry (LDF). METHODOLOGY: Pulpal blood flow of twenty maxillary incisors with no restorations or abnormal responses to sensitivity tests in healthy patients between 24 and 42 years of age was measured in perfusion units (PU). STI (isolation of only the tooth undergoing blood flow assessment) and MTI (isolation including the maxillary right to the maxillary left canine) recordings were taken with regular blood flow (RBF) and with local infiltration (LI) with vasoconstrictor. anova and Tukey HSD tests were used for statistical analysis. RESULTS: The mean PBF with regular blood flow conditions was significantly different between single tooth isolation [5.53 PU (SD ± 2.98)] and multiple tooth isolation [2.85 PU (SD ± 2.13)] (P < 0.01). When local anaesthesia was administered (LI), the PBF was significantly different between single tooth isolation [2.95 PU (SD ± 2.48)] and multiple tooth isolation [1.32 PU (SD ± 0.70)] (P < 0.05). Significant differences in PBF also existed between single tooth isolation under regular blood flow conditions and with local anaesthesia (P < 0.01), between single tooth isolation under regular blood flow conditions and multiple tooth isolation with local anaesthesia (P < 0.01), and between multiple tooth isolation under regular blood flow conditions and with local anaesthesia (P < 0.05). CONCLUSIONS: Pulpal blood flow measurements could be obtained with multiple teeth isolation and single tooth isolation. Multiple teeth isolation blocked signal contamination better. Single tooth isolation provided significantly different readings for regular blood flow and LI conditions and may therefore provide an option for pulpal blood flow assessment with LDF.

Setzer FC; Challagulla P; Kataoka SH; Trope M

2013-06-01

108

Does pupil dilation influence subfoveal choroidal laser Doppler flowmetry?  

UK PubMed Central (United Kingdom)

Purpose:? The aim of this study was to assess (i) whether pupil dilation with tropicamide influences subfoveal choroidal blood flow, as assessed by continuous laser Doppler flowmetry (LDF) and (ii) if this is the case, whether the effect is due to a haemodynamic response of the drug-induced dilation. Methods:? Following the instillation of one drop of 1% tropicamide in one eye of 18 healthy, nonsmoking volunteers (age 20-25?years), the subfoveal choroidal LDF parameters (Vel, Vol and ChBF) were recorded during 30?min, at 3-min intervals under two paradigms: through an artificial pupil (4?mm diameter) placed in front of the cornea (P1) and without this artificial pupil (P2). Results:? Tropicamide increased the pupil diameter from 3.3?±?0.4?mm (mean?±?SD) to 8.3?±?0.4?mm. Full dilation was reached at ?24?min. During this period of time, linear regression analysis demonstrated that none of the LDF parameters varied significantly (p?>?0.05), either under P1 or P2. Based on a group of 12 subjects, the smallest (%) change in the mean value of ChBF (ChBFm ) that would be detectable (sensitivity of the method, S) was found to be 2% for P1 and 6% for P2. The average coefficient of variation of ChBFm based on eight measurements during dilation was greater for P2 than for P1 by a factor of approximately 2. Conclusion:? Tropicamide had no significant influence on the subfoveal choroidal LDF parameters measured by continuous LDF during pupil dilation. Furthermore, pupil dilation did not affect ChBFm by more than the calculated minimum percentage change of 6% detectable with our method.

Palanisamy N; Riva CE; Rovati L; Cellini M; Gizzi C; Strobbe E

2013-11-01

109

Does pupil dilation influence subfoveal choroidal laser Doppler flowmetry?  

Science.gov (United States)

Purpose:? The aim of this study was to assess (i) whether pupil dilation with tropicamide influences subfoveal choroidal blood flow, as assessed by continuous laser Doppler flowmetry (LDF) and (ii) if this is the case, whether the effect is due to a haemodynamic response of the drug-induced dilation. Methods:? Following the instillation of one drop of 1% tropicamide in one eye of 18 healthy, nonsmoking volunteers (age 20-25?years), the subfoveal choroidal LDF parameters (Vel, Vol and ChBF) were recorded during 30?min, at 3-min intervals under two paradigms: through an artificial pupil (4?mm diameter) placed in front of the cornea (P1) and without this artificial pupil (P2). Results:? Tropicamide increased the pupil diameter from 3.3?±?0.4?mm (mean?±?SD) to 8.3?±?0.4?mm. Full dilation was reached at ?24?min. During this period of time, linear regression analysis demonstrated that none of the LDF parameters varied significantly (p?>?0.05), either under P1 or P2. Based on a group of 12 subjects, the smallest (%) change in the mean value of ChBF (ChBFm ) that would be detectable (sensitivity of the method, S) was found to be 2% for P1 and 6% for P2. The average coefficient of variation of ChBFm based on eight measurements during dilation was greater for P2 than for P1 by a factor of approximately 2. Conclusion:? Tropicamide had no significant influence on the subfoveal choroidal LDF parameters measured by continuous LDF during pupil dilation. Furthermore, pupil dilation did not affect ChBFm by more than the calculated minimum percentage change of 6% detectable with our method. PMID:23648126

Palanisamy, Nithiyanantham; Riva, Charles E; Rovati, Luigi; Cellini, Mauro; Gizzi, Corrado; Strobbe, Ernesto

2013-05-01

110

From Laser Induced Line Narrowing To Electromagnetically Induced Transparency in a Doppler-Broadened System  

CERN Document Server

Laser induced line narrowing effect in Doppler broadened systems was discovered thirty years ago. This effect can also be applied to recent experimental studies in high resolution spectroscopy or high precision measurements based on Electromagnetically Induced Transparency (EIT). In this report we derive an analytic expression for the linewidth of EIT resonance in a Doppler broadened system. It is shown here that the EIT linewidth is proportional to the Rabi frequency of the driving field and is independent of the Doppler width in a limiting case. This recovers the result found in the laser induced line narrowing effect by Feld and Javan. In the other limit, we recovers the usual power broadening case where the EIT linewidth is proportional to the intensity of the driving field and inversely proportional to the Doppler width.

Javan, A; Lee, H; Scully, M O; Javan, Ali; Kocharovskaya, Olga; Lee, Hwang; Scully, Marlan O.

2001-01-01

111

Application of semiconductor devices to laser-Doppler anemometry for velocity measurement  

Energy Technology Data Exchange (ETDEWEB)

The paper describes the possibilities of using semiconductor devices for laser-Doppler anemometers (LDA). This includes laser diodes at the transmitter side and PIN and Avalanche diodes at the receiver side. The advantages and disadvantages of various laser diode types are described, reference is made to problems such as focusing and wavelength stabilization and passwords are given for the use of LDA. Extensive measurements of the attainable signal-noise ratios (SNR) of photomultipliers and of a number of photodiodes from various manufacturers have shown that some models are now superior to photomultipliers. Laser diodes should be used together with photodiodes to construct miniaturized laser-Doppler anemometers, as such semiconductor LDA are much more efficient than conventional anemometers with gas lasers and photomultipliers. Miniaturized LDA construction types can, moreover, now also be used for battery operation.

Dopheide, D.; Faber, M.; Reim, G.; Taux, G.

1987-01-01

112

Sidetone generator flowmeter  

Energy Technology Data Exchange (ETDEWEB)

A flowmeter is provided which uses the sidetones generated in a cavity formed in the wall of a flowpipe or the like in response to fluid flowing past the cavity to provide a measure of the flow velocity of that fluid. The dimensions of the cavity are such as to provide a dominant vibratory frequency which is sensed by a pressure sensor. The flowmeter is adapted for use for a range of frequencies in which the Strouhal number is constant and under these conditions the vibratory frequency is directly related to the flow rate. The tone generator cavity and pressure transducer form a unit which is connected in-line in the flowpipe.

Fritz, Robert J. (Schenectady, NY)

1986-01-01

113

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

CERN Multimedia

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

114

Three interfering beams in laser Doppler velocimetry for particle position and microflow velocity profile measurements  

International Nuclear Information System (INIS)

[en] It is proposed to use three interfering and coplanar laser beams to form the probe volume of laser Doppler systems. This allows us to obtain, for each particle crossing this probe volume, a Doppler signal whose frequency amplitude spectrum exhibits two characteristic peaks. Electromagnetic calculations and experimental validations clearly demonstrate that we can estimate simultaneously, from the analysis of these two frequency peaks, the particle position along the optical axis and one velocity component. This technique is expected to have great potentialities for velocity profile measurements in microfluidic or boundary layer flows, as well as for the sizing of spherical particles

2006-05-10

115

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

116

Application of laser Doppler velocimeter to velocity measurement of charged dust particles in high electric field  

International Nuclear Information System (INIS)

[en] As a preliminary study for the collection process of dust particles in an electrostatic precipitator, a laser Doppler velocimeter with high spatial resolution and high accuracy was used to measure the moving velocity of small dust particles charged in a high electric field. For an optical system of the velocimeter, the differential type was adopted. To achieve the high sampling rate, the period-measuring system was used for obtaining the velocity data from Doppler beat signals. By means of the laser Doppler velocimeter constructed here, accurate measurements of the moving velocity and direction of dust particles as a function of the applied electrode voltage and polarity were performed over a sectional plane of the model electrostatic precipitator. The experimental results may be useful for revealing the collection process of dust particles in the high electric field and, therefore, for the design of the electrostatic precipitator. (orig.)

1980-01-01

117

Ground-based Doppler lidar of increased laser instability: Conception and design  

Science.gov (United States)

Pulsed CO2 Doppler lidars are effective tools for ground-based atmospheric wind sensing, but the high cost of the lidar transceivers, mainly due to the required high frequency stability (better than 10(exp -9) or 100 KHz), prevents their wide use in meteorology. The best approach to overcome this problem is to develop Doppler lidars that are effective at increased laser instability. This work is based on the results of a new scheme for Doppler lidar detection by the use of frequency synthesis, in a wide fluctuation bandwidth of laser instabilities, is described. A ground-based system, using this approach, is under development in the Institute of Electronics - Bulgarian Academy of Science (BAS).

Stoyanov, D. V.; Bratanov, B. M.; Naboko, V. N.; Angelova, M. D.

1992-07-01

118

Doppler- and recoil-free laser excitation of Rydberg states via three-photon transitions  

Science.gov (United States)

Three-photon laser excitation of Rydberg states by three different laser beams can be arranged in a starlike geometry that simultaneously eliminates the recoil effect and Doppler broadening. Our analytical and numerical calculations for a particular laser excitation scheme 5S1/2?5P3/2?6S1/2?nP in Rb atoms have shown that, compared to the one- and two-photon laser excitation, this approach provides much narrower linewidth and longer coherence time for both cold atom samples and hot vapors, if the intermediate one-photon resonances of the three-photon transition are detuned by more than respective single-photon Doppler widths. This method can be used to improve fidelity of Rydberg quantum gates and precision of spectroscopic measurements in Rydberg atoms.

Ryabtsev, I. I.; Beterov, I. I.; Tretyakov, D. B.; Entin, V. M.; Yakshina, E. A.

2011-11-01

119

Doppler- and recoil-free laser excitation of Rydberg states via three-photon transitions  

Energy Technology Data Exchange (ETDEWEB)

Three-photon laser excitation of Rydberg states by three different laser beams can be arranged in a starlike geometry that simultaneously eliminates the recoil effect and Doppler broadening. Our analytical and numerical calculations for a particular laser excitation scheme 5S{sub 1/2}{yields}5P{sub 3/2}{yields}6S{sub 1/2}{yields}nP in Rb atoms have shown that, compared to the one- and two-photon laser excitation, this approach provides much narrower linewidth and longer coherence time for both cold atom samples and hot vapors, if the intermediate one-photon resonances of the three-photon transition are detuned by more than respective single-photon Doppler widths. This method can be used to improve fidelity of Rydberg quantum gates and precision of spectroscopic measurements in Rydberg atoms.

Ryabtsev, I. I.; Beterov, I. I.; Tretyakov, D. B.; Entin, V. M.; Yakshina, E. A. [A. V. Rzhanov Institute of Semiconductor Physics SB RAS, Prospekt Lavrentyeva 13, 630090 Novosibirsk (Russian Federation)

2011-11-15

120

Non-contact flow velocity measurement using a Laser-Doppler anemometer  

Energy Technology Data Exchange (ETDEWEB)

The article describes the measurement principle, the design and the function of the measurement system. Application of Laser-Doppler anemometer measurements are examplified by velocity profiles obtained in an experimental waste-gase duct featuring constant air supply and exhaust.

Kahlden, T. von.

1985-12-01

 
 
 
 
121

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).

1992-01-01

122

Multipoint laser Doppler vibrometry using holographic optical elements and a CMOS digital camera  

Digital Repository Infrastructure Vision for European Research (DRIVER)

peer-reviewed , A laser Doppler vibrometer (LDV) is described in which holographic optical elements are used to provide the interferometer reference and object illumination beams. A complementary metal-oxide semiconductor camera, incorporating a digital signal processor, is used to carry out real-time ...

Connelly, Michael J.; Szecowka, Przemyslaw M.; Jallapuram, Raghavendra; Martin, Suzanne; Toal, Vincent; Whelan, Maurice P.

123

Influence Of Optical Properties and Fiber separation on Laser Doppler Flowmetry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Microcirculatory blood flow can be measured using a laser Doppler flowmetry (LDF) probe. However, the readings are affected by tissue optical properties (absorption and scattering coefficient; µa and µs) and probe geometry. In this study the influence of optical properties (µa?[0.053, 0.23] mm-1; µs...

Larsson, Marcus; Steenbergen, Wiendelt; Strömberg, Tomas

124

High-speed wave-mixing laser Doppler imaging, in vivo.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An interferometric method for parallel optical spectroscopy in the kilohertz range is reported, as well as its experimental validation in the context of high speed laser Doppler imaging in vivo. The interferometric approach enables imaging in the low light conditions of a 2 kHz frame rate recording ...

Atlan, Michael; Gross, Michel; Vitalis, Tania; Rancillac, Armelle; Rossier, Jean; Boccara, Claude

125

Vibration characteristics of aluminum material and its influences on laser Doppler voice acquisition  

Science.gov (United States)

Laser Doppler technology is widely used in precision vibration measurement such as voice acquisition. The fundamental of voice acquisition is to detect the vibration of targets induced by sound wave using a Laser Doppler voice acquisition system, and then demodulate the voice signal from interference signal. Therefore the target's vibration characteristics will be the principal factor influencing the effect of voice acquisition. In this paper, we focus on the plane structure's vibration characteristics caused by voice. There are mainly two parts in this paper, simulation and experimental verify. In simulation, the finite element method is used. The Finite Element Analysis method is widely used in material properties analysis, dynamic analysis, and acoustic analysis. Through finite element analysis method, the plane structure models of thick smooth aluminum are established by ANSYS. Then the frequency responses of different constraints are compared. The Laser Doppler voice acquisition system is applied to test and verify the simulation results. The response characteristics of aluminum board under different excitation frequency are measured. The experimental results and simulation results are compared to verify the correctness and reasonableness of simulation. At the same time, this provides theoretical guidance for Laser Doppler voice acquisition system to choose targets and improve voice acquisition performance.

Zhang, Yu-ze; Li, Li-yan; Tong, You-wan; Zeng, Hua-lin; Zhou, Yan

2013-09-01

126

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

1993-01-01

127

Dual beam translator for use in laser doppler anemometry  

Energy Technology Data Exchange (ETDEWEB)

A method is described for attaining substantial spacial coincidence of the intersection volumes of two pairs of intersecting light beams in a fluid flow conduit in a Doppler anemometry device. The method comprises focusing the two pairs of light beams with a beam focusing means and selectively translating the beam paths of at least one of the pairs of beams. The paths are translated in a direction parallel to the original beam paths by a pair of rotatable transparent optical means provided in the beam paths between the beam focusing means and the fluid flow conduit.

Brudnoy, D.M.

1987-01-20

128

Vibration measurements on rotating machinery using laser Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

This paper explores the use of laser vibrometry for vibration measurement directly from a rotating component. The presence of a surface velocity component due to the rotation itself is shown to create a strong measurement dependency on vibration perpendicular to the intended measurement direction. Particular ambiguity results at synchronous frequencies. A mathematical means to resolve the genuine vibration components from two simultaneous laser vibrometer measurements is presented and shown to be effective in the study of nonsynchronous rotor vibrations.

Rothberg, S.J.; Halliwell, N.A. (Loughborough Univ. of Technology, Leicestershire (United Kingdom). Dept. of Mechanical Engineering)

1994-07-01

129

Comparison of blood flow assessment between laser Doppler velocimetry and the hydrogen gas clearance method in ischemic intestine in dogs.  

UK PubMed Central (United Kingdom)

Blood flow of the colon and the ileum was measured before and after intestinal devascularization by laser Doppler velocimetry and the hydrogen gas clearance technique in 10 dogs in order to evaluate the clinical usefulness of laser Doppler velocimetry. The submucosal blood flow of the colon and the ileum measured by the hydrogen gas clearance method was significantly decreased, as was the subserosal blood flow of both sites measured by laser Doppler velocimetry. There was a linear relationship between the flow values using the two methods both in the colon (r = 0.7192, p less than 0.001) and in the ileum (r = 0.7646, p less than 0.001). These data suggested laser Doppler velocimetry may be a useful method to assess the degree of intestinal ischemia because of its noninvasiveness and good correlation with submucosal blood flow by the hydrogen gas clearance technique.

Oohata Y; Mibu R; Hotokezaka M; Ikeda S; Nakahara S; Itoh H

1990-11-01

130

Fiber-based multi-beam laser Doppler vibrometer for measuring transient vibrations  

Science.gov (United States)

This article presents a novel fiber-based multi-beam laser Doppler vibrometer (LDV). In this design, a single wavelength laser source at 1550 nm combined with several acousto-optic modulators (AOM) form the transmitter head of the LDV. At the receiver side, one single high-speed photo-detector is employed, instead of multiple detectors according to other reported multi-beam laser Doppler vibrometer.1, 2 Utilization of spatial encoding technique allows us to produce transmitted laser beams with different frequency shifts. In this work, a laser source passes through a sequence of totally four AOMs at different regimes, producing a 4×5 laser beam matrix which is then sent onto different points of vibrating targets for measurement. The backscattered light signals are collected back into a single mode fiber by a fiber collimator and combined with a common reference beam. This mixture of optical signals passes through an Erbium Doped Fiber Amplifier (EDFA) before it is detected by a high-speed fiber-based InGaAs photo-detector. With a digital demodulation algorithm implemented in Labview, the phase variations and thus the vibrations of different testing points can be extracted separately from their corresponding frequency bands. The experimental results show it is possible to do a precise vibration measurement on twenty testing points simultaneously using this novel multi-beam LDV.

Guo, M.; Fu, Y.; Phua, P. B.

2011-02-01

131

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

Science.gov (United States)

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

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

2010-09-01

132

Monitoring of cortical blood flow: clinical relevance of experimental laser Doppler studies.  

Science.gov (United States)

Continuous monitoring of cortical blood flow provides real time information of CBF-changes during neurosurgical operations and on the neurointensive care unit. Laser Doppler flowmetry is a continuous, noninvasive technique suitable for measurement of the cortical microcirculation. In a number of experimental studies we have analyzed the characteristics of this method for cortical blood flow monitoring. The high spatial resolution of laser Doppler flowmetry and the heterogeneity of the cortical microvascular network results in a scatter of flow values over a wide range depending on the site of measurement. Data collection from different spots and calculation of frequency histogram may serve as a measure of cortical blood flow. For clinical application instead of single fiber probes a multispot measurement approach will provide a reliable cortical blood flow monitoring. The use of continuous techniques will lead to a better understanding of cerebral hemodynamics under pathological conditions. PMID:8837067

Ungersböck, K; Heimann, A; Kempski, O

1996-06-01

133

Monitoring of cortical blood flow: clinical relevance of experimental laser Doppler studies.  

UK PubMed Central (United Kingdom)

Continuous monitoring of cortical blood flow provides real time information of CBF-changes during neurosurgical operations and on the neurointensive care unit. Laser Doppler flowmetry is a continuous, noninvasive technique suitable for measurement of the cortical microcirculation. In a number of experimental studies we have analyzed the characteristics of this method for cortical blood flow monitoring. The high spatial resolution of laser Doppler flowmetry and the heterogeneity of the cortical microvascular network results in a scatter of flow values over a wide range depending on the site of measurement. Data collection from different spots and calculation of frequency histogram may serve as a measure of cortical blood flow. For clinical application instead of single fiber probes a multispot measurement approach will provide a reliable cortical blood flow monitoring. The use of continuous techniques will lead to a better understanding of cerebral hemodynamics under pathological conditions.

Ungersböck K; Heimann A; Kempski O

1996-06-01

134

Fiber optic confocal laser Doppler velocimeter using an all-fiber laser source for high resolution measurements.  

Science.gov (United States)

We demonstrate and analyze a novel fiber optic confocal laser Doppler velocimeter using an ultra-narrow linewidth all-fiber laser source centered at around 1550 nm (eye-safe region). The narrow spectral linewidth of the fiber laser (lasers or He-Ne lasers based systems. The directional optical circulator based design used in our system is much simpler to implement and is power conserving compared to the conventional Michelson interferometer based designs. We perform Gaussian beam propagation analysis by using the ABCD law to study the performance of the confocal design. The analysis is in good accord with our experimental results. The confocal design is capable of providing ultrahigh spatial resolution (~5microm, in both lateral and longitudinal directions) for high-precision velocity distribution measurement applications. PMID:19498637

Sharma, Utkarsh; Chen, Gang; Kang, Jin; Ilev, Ilko; Waynant, Ronald

2005-08-01

135

Three-dimensional laser doppler velocimetry for flow analysis in static mixing elements; Dreidimensionale Laser-Doppler-Velocimetry zur Analyse der Stroemung in statischen Mischelementen  

Energy Technology Data Exchange (ETDEWEB)

Flow patterns in the geometrically complex flow space of a static mixer of the SMX type were analyzed by laser doppler velocimetry. The set-up enabled direct and simultaneous measurements of the three orthogonal velocity components of the velocity vector. The optical configuration of the measuring system was such that adaptation of the refractory index was unnecessary. The experimental velocities were validated by numeric simulations. Periodicity and symmetry characteristics of crawling flow are presented, and their dependence on the material characteristics is pointed out. The kinematics of the flow is identified, in consideration of velocities, twist, shear and elongation in the flow field. The mixing processes can be analyzed with the aid of the measured material deformation parameters. [German] Mit Hilfe der laser-doppler-velocimetry (LDV) wird die Stroemung im geometrisch komplizierten Stroemungsraum eines statischen Mischers vom Typ SMX analysiert. Der entwickelte Messsystemaufbau ermoeglicht es, die drei orthogonalen Geschwindigkeitskomponenten des Geschwindigkeitsvektors direkt und simultan zu erfassen. Aufgrund der optischen Konfiguration des Messsystems kann zudem auf eine Brechungsindexanpassung verzichtet werden. Die experimentell ermittelten Geschwindigkeiten werden durch die Ergebnisse einer numerischen Simulation bestaetigt. Periodizitaets- und Symmetrieeigenschaften der schleichenden Stroemung werden dargestellt und ihre Abhaengigkeit von den Stoffeigenschaften verdeutlicht. Die Kinematik der Stroemung wird ersichtlich, wobei neben den Geschwindigkeiten auch auf Dehnungen, Drehungen und Scherungen im Stromfeld eingegangen wird. Die Mischvorgaenge koennen mit Hilfe der ermittelten materiellen Deformationsgroessen bewertet werden. (orig.)

Leitner, M.W.

2001-07-01

136

Characterisation of very low frequency oscillations in laser Doppler perfusion signals with a singular spectrum analysis.  

Science.gov (United States)

Laser Doppler (LD) perfusion signals consist of a number of superimposed frequencies that span a wide range. Singular spectrum analysis (SSA) was used to characterise the very low frequency (VLF) components as this method can extract frequencies of interest from the time domain. Its utility is demonstrated on a sex health clinical data set where the focus was on VLF oscillations. A significant change in this frequency range can be measured with SSA when the subject is undergoing erotic stimulation. PMID:21382383

Azulay, David-Olivier; Brain, Phil; Sultana, Stefan R

2011-03-05

137

Characterisation of very low frequency oscillations in laser Doppler perfusion signals with a singular spectrum analysis.  

UK PubMed Central (United Kingdom)

Laser Doppler (LD) perfusion signals consist of a number of superimposed frequencies that span a wide range. Singular spectrum analysis (SSA) was used to characterise the very low frequency (VLF) components as this method can extract frequencies of interest from the time domain. Its utility is demonstrated on a sex health clinical data set where the focus was on VLF oscillations. A significant change in this frequency range can be measured with SSA when the subject is undergoing erotic stimulation.

Azulay DO; Brain P; Sultana SR

2011-05-01

138

Diagnosis of arterial occlusive disease of the lower extremities by laser Doppler flowmetry.  

Science.gov (United States)

Laser Doppler Flowmetry offers the possibility of non-invasive and continuous recording of tissue blood flow. Skin blood flux in resting state and during postocclusive reactive hyperemia was measured at the pulpa of the toe in 21 normal lower limbs and in 58 limbs with arterial occlusive disease. Proper assessment of postischemic flux- and time- parameters (beginning of reactive hyperemia, peak flux, time of peak flux and duration of hyperemic flux) permits accurate separation of healthy and diseased limbs. PMID:3058833

Van den Brande, P; Welch, W

139

Diagnosis of arterial occlusive disease of the lower extremities by laser Doppler flowmetry.  

UK PubMed Central (United Kingdom)

Laser Doppler Flowmetry offers the possibility of non-invasive and continuous recording of tissue blood flow. Skin blood flux in resting state and during postocclusive reactive hyperemia was measured at the pulpa of the toe in 21 normal lower limbs and in 58 limbs with arterial occlusive disease. Proper assessment of postischemic flux- and time- parameters (beginning of reactive hyperemia, peak flux, time of peak flux and duration of hyperemic flux) permits accurate separation of healthy and diseased limbs.

Van den Brande P; Welch W

1988-07-01

140

Laser Doppler velocimetry applied to the measurement of local and global wind  

Energy Technology Data Exchange (ETDEWEB)

The analysis of radiation scattered from naturally occurring aerosols carried along by the wind provides a powerful tool for the study of wind structure and enables the air flow to be studied from a single, non-perturbing, measuring station. In this paper, we outline the current status of wind measurement from ground-based, air borne and space platforms. The potential for using Laser Doppler Velocimetry on a range of applications with wind turbine generators is discussed. (author).

Vaughan, J.M.; Forrester, P.A. (Royal Signals and Radar Establishment, Malvern (GB))

1989-01-01

 
 
 
 
141

3D flow measurements in nuclear fuel rod bundles using Laser Doppler velocimetry  

International Nuclear Information System (INIS)

[en] Using a two color Laser Doppler velocimeter, mean velocities and turbulence intensities have been measured in a complex geometric structure close to the 17 x 17 square lattice nuclear fuel rod bundles. Good accuracy of the control volume location and high data rate acquisition have been achieved. Comparisons are made between four different optical configurations measuring the same phenomenon. In this paper attention is focused not only on understandable discrepancies but also on unpredictable minor uncertainties

1991-01-01

142

Anisotropic sub-Doppler laser cooling in dysprosium magneto-optical traps  

CERN Multimedia

Magneto-optical traps (MOTs) of Er and Dy have recently been shown to exhibit population-wide sub-Doppler cooling due to their near degeneracy of excited and ground state Lande g factors. We discuss here an additional, unusual intra-MOT sub-Doppler cooling mechanism that appears when the total Dy MOT cooling laser intensity and magnetic quadrupole gradient increase beyond critical values. Specifically, anisotropically sub-Doppler-cooled cores appear, and their orientation with respect to the quadrupole axis flips at a critical ratio of the MOT laser intensity along the quadrupole axis versus that in the plane of symmetry. This phenomenon can be traced to a loss of the velocity-selective resonance at zero velocity in the cooling force along directions in which the atomic polarization is oriented by the quadrupole field. We present data characterizing this anisotropic laser cooling phenomenon and discuss a qualitative model for its origin based on the extraordinarily large Dy magnetic moment and Dy's near degen...

Youn, Seo Ho; Lev, Benjamin L

2010-01-01

143

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

144

A novel design and analysis of acoustical signal detection based on laser Doppler  

Science.gov (United States)

A novel acoustical-vibration signal detection system based on laser Doppler is proposed. The system is based on the M - Z interferometer optical system, and used more adaptive piezoelectric ceramics modulation and demodulation system to restore signal. The whole system satisfies the requirements of non-contact, remote, high sensitivity and anti-interference. It has the advantages of strong stability, compact light path, low cost and easy miniaturization compared with heterodyne interferometer based on Acoustical Optical Modulator (AOM). At last the influence of the laser power fluctuations (frequency instability and amplitude instability) on the system is analyzed theoretically.

Meng, Xue; Li, Li-Yan; Zeng, Hua-Lin; Zhou, Yan

2011-06-01

145

Torsional vibration measurements on rotating shaft system using laser doppler vibrometer  

Science.gov (United States)

In this work, a laser torsional vibrameter was used to measure the torsion vibration of a rotating shaft system under electrical network impact. Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) are non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. Furthermore, a highly complex shafting system is analyzed by a modified Riccati torsional transfer matrix. The system is modeled as a chain consisting of an elastic spring with concentrated mass points, and the multi-segments lumped mass model is established for this shafting system. By the modified Riccati torsional transfer matrix method, an accumulated calculation is effectively eliminated to obtain the natural frequencies. The electrical network impacts can activize the torsional vibration of shaft system, and the activized torsion vibration frequencies contained the natural frequencies of shaft system. The torsional vibrations of the shaft system were measured under electrical network impacts in laser Doppler torsional vibrometer. By comparisons, the natural frequencies by measurement were consistent with the values by calculation. The results verify the instrument is robust, user friendly and can be calibrated in situ. The laser torsional vibrometer represents a significant step forward in rotating machinery diagnostics.

Xiang, Ling; Yang, Shixi; Gan, Chunbiao

2012-11-01

146

High-resolution (Doppler-limited) spectroscopy using quantum-cascade distributed-feedback lasers  

International Nuclear Information System (INIS)

[en] Lasing characteristics were evaluated for distributed-feedback quantum-cascade (QC) lasers operating in a continuous mode at cryogenic temperatures. These tests were performed to determine the QC lasers close-quote suitability for use in high-resolution spectroscopic applications, including Doppler-limited molecular absorption and pressure-limited lidar applications. By use of a rapid-scan technique, direct absorbance measurements of nitric oxide (NO) and ammonia (NH3 ) were performed with several QC lasers, operating at either 5.2 or 8.5 ?m . Results include time-averaged linewidths of better than 40MHz and long-term laser frequency reproducibility, even after numerous temperature cycles, of 80MHz or better. Tuning rates of 2.5 cm-1 in 0.6ms can be easily achieved. Noise-equivalent absorbance of 3x10-6 was also obtained without optimizing the optical arrangement. copyright 1998 Optical Society of America

1998-01-01

147

Soap film gas flowmeter  

Energy Technology Data Exchange (ETDEWEB)

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.

Lalin, H.S.; Bermudez, J.E.; Fleming, W.T.

1987-09-08

148

Photochemically induced spinal cord ischaemia in rats: assessment of blood flow by laser Doppler flowmetry.  

Science.gov (United States)

A photochemical technique was used to create central nervous system ischaemia in rats. Changes in blood flow in the spinal cord were assessed by laser Doppler flowmetry. The Th11 spinal cord segment was irradiated by an argon ion laser after intravenous injection of an organic dye, erythrosin B, to rats with or without a laminectomy. In the group of laminectomized rats, laser irradiation for 5 s did not influence cord blood flow, but 10 s irradiation caused a 25% decrease of blood flow, which normalized within 20 min. Decreases of 50 and 80% in spinal cord blood flow were noted after 20 s and after 1 min of laser irradiation, respectively, with no recovery observed after 20 min. In the group of rats without a laminectomy, 1 min of laser irradiation caused approximately a 25% decrease of spinal cord blood flow, which gradually recovered within 12 min, whereas 5 min of laser irradiation caused a more severe reduction of spinal cord blood flow (45%) with some recovery was observed 30 min later. We could thus confirm that the interaction between a photosensitizing dye and laser irradiation reduced the regional spinal cord blood flow and the extent of this effect could be modified by varying the duration of laser irradiation. The present results therefore provide further support for using this photochemical technique to create animal models of central nervous system ischaemia. PMID:7942056

Hao, J X; Herregodts, P; Lind, G; Meyerson, B; Seiger, A; Wiesenfeld-Hallin, Z

1994-06-01

149

Photochemically induced spinal cord ischaemia in rats: assessment of blood flow by laser Doppler flowmetry.  

UK PubMed Central (United Kingdom)

A photochemical technique was used to create central nervous system ischaemia in rats. Changes in blood flow in the spinal cord were assessed by laser Doppler flowmetry. The Th11 spinal cord segment was irradiated by an argon ion laser after intravenous injection of an organic dye, erythrosin B, to rats with or without a laminectomy. In the group of laminectomized rats, laser irradiation for 5 s did not influence cord blood flow, but 10 s irradiation caused a 25% decrease of blood flow, which normalized within 20 min. Decreases of 50 and 80% in spinal cord blood flow were noted after 20 s and after 1 min of laser irradiation, respectively, with no recovery observed after 20 min. In the group of rats without a laminectomy, 1 min of laser irradiation caused approximately a 25% decrease of spinal cord blood flow, which gradually recovered within 12 min, whereas 5 min of laser irradiation caused a more severe reduction of spinal cord blood flow (45%) with some recovery was observed 30 min later. We could thus confirm that the interaction between a photosensitizing dye and laser irradiation reduced the regional spinal cord blood flow and the extent of this effect could be modified by varying the duration of laser irradiation. The present results therefore provide further support for using this photochemical technique to create animal models of central nervous system ischaemia.

Hao JX; Herregodts P; Lind G; Meyerson B; Seiger A; Wiesenfeld-Hallin Z

1994-06-01

150

Ultrasonic flowmeters: a progress report  

International Nuclear Information System (INIS)

[en] This progress report describes the components and system configuration of the prototype ultrasonic flowmeter and initial flow testing. It is the second in a series of progress reports on the development and testing of ultrasonic flowmetering concepts. The greatest advantage of an ultrasonic flowmeter is that the instrument can be installed on the outside of a pipe with no modifications required. The flow is measured through the pipe walls. However, complex electronic systems are needed for the measurements. The ultrasonic flowmeter features: high resolution limited only by the electronics; fast response since there are no moving parts; measurement over a wide range of flow conditions; portability; and can be used for a range of different pipe sizes. No current alternative method of measuring flow combines all these advantages

1980-01-01

151

Doppler velocimetry on microparticles trapped and propelled by laser light in liquid-filled photonic crystal fiber.  

UK PubMed Central (United Kingdom)

Laser Doppler velocimetry is used to measure very accurately the velocity and position of a microparticle propelled and guided by laser light in liquid-filled photonic crystal fiber. Periodic variations in particle velocity are observed that correlate closely with modal beating between the two lowest order guided fiber modes.

Garbos MK; Euser TG; Schmidt OA; Unterkofler S; Russell PS

2011-06-01

152

Doppler velocimetry on microparticles trapped and propelled by laser light in liquid-filled photonic crystal fiber.  

Science.gov (United States)

Laser Doppler velocimetry is used to measure very accurately the velocity and position of a microparticle propelled and guided by laser light in liquid-filled photonic crystal fiber. Periodic variations in particle velocity are observed that correlate closely with modal beating between the two lowest order guided fiber modes. PMID:21633435

Garbos, M K; Euser, T G; Schmidt, O A; Unterkofler, S; Russell, P St J

2011-06-01

153

Float-type flowmeter  

Energy Technology Data Exchange (ETDEWEB)

This patent describes an improvement in a float-type flowmeter for measuring the rate of a given flow of fluid. It has a float chamber; and inlet opening; means for channeling the sampled portion of the flow into the first end of the float chamber; and outlet opening; a float, located in the float chamber; and flow rate indicating means. The improvement comprises: means for ratably mounting the inlet opening so that it can be rotated to face into the flow; a rotatably mounted deflection surface, mounted so it can be deflected by the flow so as to minimize its resistance to the flow; and means for mechanically linking the deflection surface and the inlet opening so that when the deflecting surface is rotated so as to minimize its resistance to the flow, the inlet opening faces into the flow.

Daly, D.C.

1990-01-01

154

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

International Nuclear Information System (INIS)

The thesis describes a new high precision measurement of the 1S-2S transition frequency in muonium, carried out at the ISIS facility at the Rutherford Appleton Laboratory, using a solid-state laser system. The focus of the thesis is mainly the work carried out on the pulsed part of the laser system. The transition frequency is measured by the Doppler-free spectroscopy. The two-photon 1S-2S transition is detected by observing the positive muon released after subsequent photo-ionisation from the 2S state by a third photon from the same laser field. An accurate frequency standard for the experiment was provided by a Doppler-free transition in molecular iodine. A cw Ti:sapphire laser operating around 732 nm locked to this reference transition provided a stable output for injection seeding the pulsed alexandrite laser. This has been optimised and modified to achieve a stable operation in a single transverse and longitudinal mode. There were stringent requirements on the laser pulse timing relative to an external trigger in order to synchronise the laser pulse with the muon pulse from the ISIS facility. A method of cavity length stabilisation, which reduced the jitter of the laser from approximately 20 ?s to 100ns and allowed us to trigger the laser externally, is described. This was performed in two stages using an intracavity, piezo-mounted, quartz plate and two fast, electro-optic modulators. The frequency chirp of the laser output, measured using a heterodyne technique 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. (author)

1998-01-01

155

Drop-size measurement techniques for sprays: comparison of Malvern laser-diffraction and Aerometrics phase/Doppler.  

UK PubMed Central (United Kingdom)

The purpose of this paper is to compare the drop sizing results of an Aerometrics phase/Doppler particle analyzer with those of a Malvern laser-diffraction instrument. Measurements were performed on a small pressure-swirl atomizer. Since the laser-diffraction instrument measures a line-of-sight average through different regions of the spray while the phase/Doppler instrument characterizes the spray in a small volume, a conversion procedure was necessary prior to comparison. After conversion to equivalent forms, the point-measured average drop sizes exhibited similar trends throughout the spray, but the phase/Doppler values were generally larger. The total volume flow rate measured by the phase/Doppler instrument was inconsistent at different axial locations but significantly larger than the actual value at most locations.

Dodge LG; Rhodes DJ; Reitz RD

1987-06-01

156

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Laser Doppler visualisation of the velocity field by excluding the influence of multiparticle scattering  

Science.gov (United States)

The method of laser Doppler visualisation and measurement of the velocity field in gas and liquid flows by suppressing the influence of multiparticle scattering is discussed. The cross section of the flow under study is illuminated by a laser beam transformed by an anamorphic optical system into a laser sheet. The effect of multiparticle scattering is eliminated by obtaining differential combinations of frequency-demodulated images of the laser sheet in different regions of the angular spectrum of scattered light.

Dubnishchev, Yu N.; Chugui, Yu V.; Kompenhans, J.

2009-10-01

157

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

Science.gov (United States)

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.

Laurantzon, F.; Örlü, R.; Segalini, A.; Alfredsson, P. H.

2010-12-01

158

Optic simulation and optimization of a laser Doppler velocity profile sensor for microfluidic applications  

Science.gov (United States)

The application of laser Doppler velocimetry to microfluidic flows is usually prevented due the large size of the measurement volume of typically 100 ?m. A significantly higher spatial resolution can be achieved with the concept of the laser Doppler velocity profile sensor. However, the resolution is limited by wavefront distortions caused by aberrations of the optical setup. In this work, optical simulation software was employed to investigate the aberrations caused by the profile sensor setup by going from ideal to real lenses step by step. As the main source for the aberrations, the aspheric lens for collimating the laser beams was identified. On the basis of this simulation the setup of the velocity profile sensor could be optimized. The sensor was employed to measure the velocity profile in a microchannel. A spatial resolution of 1.2 ?m and a relative uncertainty of the velocity of 0.25% result, confirming the findings of the simulation. This demonstrates the potential of the optimized velocity profile sensor for flow measurements at the microscale.

Büttner, Lars; Skupsch, Christoph; König, Jörg; Czarske, Jürgen

2010-07-01

159

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

Kapralov S.V.; Shapkin Y.G.; Frolov I.A.; Afanasieva G.A.

2011-01-01

160

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

 
 
 
 
161

Laser-Doppler vibrating tube densimeter for measurements at high temperatures and pressures  

International Nuclear Information System (INIS)

A laser-Doppler vibrometer was used to measure the vibration of a vibrating tube densimeter for measuring P-V-T data at high temperatures and pressures. The apparatus developed allowed the control of the residence time of the sample so that decomposition at high temperatures could be minimized. A function generator and piezoelectric crystal was used to excite the U-shaped tube in one of its normal modes of vibration. Densities of methanol-water mixtures are reported for at 673 K and 40 MPa with an uncertainty of 0.009 g/cm3.

2007-01-01

162

Adaptive Model-Based Mine Detection/Localization using Noisy Laser Doppler Vibration Measurements  

Energy Technology Data Exchange (ETDEWEB)

The acoustic detection of buried mines is hampered by the fact that at the frequencies required for obtaining useful penetration, the energy is quickly absorbed by the ground. A recent approach which avoids this problem, is to excite the ground with a high-level low frequency sound, which excites low frequency resonances in the mine. These resonances cause a low-level vibration on the surface which can be detected by a Laser Doppler Vibrometer. This paper presents a method of quickly and efficiently detecting these vibrations by sensing a change in the statistics of the signal when the mine is present. Results based on real data are shown.

Sullivan, E J; Xiang, N; Candy, J V

2009-04-06

163

A high-resolution laser Doppler anemometer: design, qualification, and uncertainty  

Energy Technology Data Exchange (ETDEWEB)

A new high-resolution laser Doppler anemometer (LDA) has been developed with a working distance of 350 mm, allowing operation in lab-scale wind tunnels. The measurement volume size is 35 {mu}m in diameter by 60 {mu}m in length, allowing resolution of the smallest turbulence scales even at fairly high Reynolds numbers. The controversial question of velocity and validation bias in LDA data is resolved with an experimental method for measuring and removing those effects. Uncertainty estimates are also derived for all the mean and Reynolds stress measurements. (orig.)

DeGraaff, D.B.; Eaton, J.K. [Stanford Univ., CA (United States). Dept. of Mechanical Engineering

2001-05-01

164

Homodyne laser Doppler vibrometer on silicon-on-insulator with integrated 90 degree optical hybrids.  

UK PubMed Central (United Kingdom)

A miniaturized homodyne laser Doppler vibrometer (LDV) with a compact 90° optical hybrid is experimentally demonstrated on a CMOS compatible silicon-on-insulator (SOI) platform. Optical components on this platform usually have inadequate suppressions of spurious reflections, which significantly influence the performance of the LDV. Numerical compensation methods are implemented to effectively decrease the impact of these spurious reflections. With the help of these compensation methods, measurements for both super-half-wavelength and sub-half-wavelength vibrations are demonstrated. Results show that the minimal detectable velocity is around 1.2 ?m/s.

Li Y; Baets R

2013-06-01

165

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

International Nuclear Information System (INIS)

[en] 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)

2001-01-01

166

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

Energy Technology Data Exchange (ETDEWEB)

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)

Taishi, Tsuyoshi; Yamanaka, Gentaro; Kikura, Hiroshige; Aritomi, Masanori [Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors

2001-07-01

167

Measurement of fluid velocity development in laminar pipe flow using laser Doppler velocimetry  

Science.gov (United States)

In this paper we present a non-intrusive experimental approach for obtaining velocity gradient profiles in a transparent smooth pipe under laminar flow conditions (Re = 925) using a laser Doppler velocimeter (LDV). Measurements were taken within the entrance region of the pipe at l = 300 mm and l = 600 mm from the pipe inlet, in addition to measurements of the fully developed flow at l = 1800 mm. The obtained results show how the velocity profile from upstream of the pipe develops into a classical laminar profile downstream, which matches the theoretical profile well. Additionally, a brief summary of historical information about the development of flow measurement techniques, in particular LDV, is provided.

Molki, Arman; Khezzar, Lyes; Goharzadeh, Afshin

2013-09-01

168

Use of a laser doppler vibrometer for high frequency accelerometer characterizations  

Energy Technology Data Exchange (ETDEWEB)

A laser doppler vibrometer (LDV) is being used for high frequency characterizations of accelerometers at Sandia National Laboratories (SNL). A LDV with high frequency (up to 1.5 MHz) and high velocity (10 M/s) capability was purchased from a commercial source and has been certified by the Primary Electrical Standards Department at SNL. The method used for this certification and the certification results are presented. Use of the LDV for characterization of accelerometers at high frequencies and of accelerometer sensitivity to cross-axis shocks on a Hopkinson bar apparatus is discussed.

Bateman, V.I.; Hansche, B.D.; Solomon, O.M.

1995-12-31

169

Blood flow measurement in extracorporeal circulation using self-mixing laser diode  

Science.gov (United States)

To measure blood flow rate in ex-vivo circulation, we propose an optical Doppler flowmeter based on the self-mixing effect within a laser diode (SM-LD). Advantages in adopting SM-LD techniques derive from reduced costs, ease of implementation and limited size. Moreover, the provided contactless sensing allows sensor reuse, hence further cost reduction. Preliminary measurements performed on bovine blood are reported, thus demonstrating the applicability of the proposed measurement method.

Cattini, Stefano; Norgia, Michele; Pesatori, Alessandro; Rovati, Luigi

2010-02-01

170

Application of laser-Doppler velocimetry to hydrodynamic investigation of a mixed flow tubular casing pump  

Energy Technology Data Exchange (ETDEWEB)

The hydrodynamic improvement of centrifugal pump impellers require detail of flow velocity not only in stationary sections of the pump but also between the rotating blades of the impeller. The laser-Doppler velocimetry discussed in this paper represents the latest in remote non-contacting velocity measurement using laser technology. The basic principals and the signal processing are discussed using a tubular type mixed-flow centrifugal pump emphasizing flow measurements inside the rotating impeller flow channels. Test data provide insight into the effect of non-uniform inlet flows at the impeller eye due to inlet elbows, diffusors, etc. Also addressed are the effects of manufacturing errors of hydraulic components of high specific speed pumps on velocity distribution and pump performance.

Radke, M.; Siekmann, H.E.; Schroeter, R.

1986-06-01

171

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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 maneira 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 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 < 0.001). Different non-statistically significant parameters were also observed. CONCLUSION: Doppler sonography is an efficient tool for the diagnosis of shunt patency and TIPS related complications such as stenosis. However, it is necessary to study a larger number of patients in order to determine a group of parameters that would help in the follow-up of these patients, thus using portal angiography only for indicated treatment.

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

2004-01-01

172

Investigation of the acceleration of aluminum particles behind a shock wave using instantaneous Laser Doppler Velocimetry  

Science.gov (United States)

The acceleration of aluminum particles with a 5?m diameter in the flow field behind an incident shock wave was investigated experimentally in a 10-m long and 70 mm inner diameter shock tube. By means of instantaneous Laser Doppler Velocimetry (LDV) the velocity of the particles was observed directly. The light scattered by the moving particles is Doppler shifted and sent to the laser Doppler velocimeter. The velocimeter essentially consists of a phase-stabilized Michelson interferometer used as a sensitive spectrometer. An electro-optical circuit ensures the phase stabilization that results in a voltage signal independent of the scattered light intensity and proportional to the mean velocity of the particles at the measurement point. Because of the very short response time (1?s) of the LDV system used here, the latter gives a continuous real-time signal of the particle acceleration. To avoid particle oxidation the particles were accelerated by a high-speed nitrogen gas flow. From the measured velocity the dimensionless drag coefficient was calculated. The drag coefficient is related to the fluid dynamic force exerted by the gas on the particles. The experimental data were compared to theoretical models from the literature. A significant deviation between the model and the experimental data was observed. This deviation is supposed to be induced by the shock wave, which hits the particles and breaks them into pieces of a smaller diameter. Further experiments will be carried out in the future to check the size distribution of the particles after the shock has gone past them.

Schlöffel, G.; Bastide, M.; Bachmann, S.; Mundt, Ch.; Seiler, F.

2009-06-01

173

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; Huber FX; Meeder PJ; Muhr G; Buchholz J

2002-01-01

174

Comparison of scanning beam and whole field laser Doppler perfusion imaging  

Science.gov (United States)

Currently, laser perfusion imaging (LDPI) is undergoing a technology shift from scanning beam perfusion imagers to whole field systems. The latter can be subdivided in laser Doppler methods systems based on high speed CMOS cameras, and laser speckle contrast analysis (LASCA) technologies using slow imaging arrays, mostly CCD-based. In scanning beam systems, a collimated laser beam scans the tissue with diffusely back reflected light being captured with a single detector. In whole field systems a large tissue area is illuminated, and the reflected light is imaged onto an array and captured at once. Unlike scanning beam systems, both whole field methods enable perfusion imaging at video rate. In this study we experimentally compare the scanning beam LDPI principle with whole field LDPI, using Intralipid phantoms. For the tissue phantoms, the Monte Carlo simulation technique will be used as a reference. From measurements on Intralipid phantoms compared to Monte Carlo, we conclude that in whole field LDPI the flux image, representing the first order moment of the power spectrum of photocurrent fluctuations is much closer related to real perfusion than for scanning beam systems. This difference can be explained in terms of the different behaviour of dynamic speckle patterns generated in both methods, in response to varying tissue optical properties.

Steenbergen, Wiendelt; Hondebrink, Erwin; van Leeuwen, Ton G.; Draijer, Matthijs J.

2010-02-01

175

Permanent magnet flowmeter having improved output terminal means  

Energy Technology Data Exchange (ETDEWEB)

Disclosed is an improved permanent magnet flowmeter capable of withstanding bending stresses in the direction of induced emf signals. The flowmeter includes a unique terminal arrangement integrally formed with the flowmeter by trepanning opposing wall sections of the flowmeter body. The terminal arrangement provides increased flowmeter sensitivity by increasing the strength of the induced emf signals.

August, Charles (Darien, IL); Myers, Harry J. (Downers Grove, IL)

1984-01-01

176

Nailfold capillaroscopy and blood flow laser-doppler analysis of the microvascular damage in systemic sclerosis: preliminary results  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objectives: Systemic sclerosis (SSc) is characterized by altered microvascular structure and function. Nailfold videocapillaroscopy (NVC) is the tool to evaluate capillary morphological structure and laser-Doppler Blood flowmetry (LDF) can be used to estimate cutaneous blood flow of microvessels. Th...

M.E. Secchi; A. Sulli; C. Pizzorni; M. Cutolo

177

Comparison between intensity correlation and Fourier transform of the time interval probability techniques applied to laser Doppler velocimetry.  

UK PubMed Central (United Kingdom)

In this paper we study the improvement in a laser Doppler velocimetry experiment when the Fourier transform of the time interval probability is measured instead of the intensity correlation function. The errors involved in determination of the velocity are found to be greatly improved for low scattered intensities.

Alvarez JM; Rebolledo MA; Tornos J

1989-09-01

178

Evaluation of Influence of Acupuncture and Electro-Acupuncture for Blood Perfusion of Stomach by Laser Doppler Blood Perfusion Imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The objective of this study is to observe effects of acupuncture and electro-acupuncture (EA) on blood perfusion in the stomach, and probe into the application of laser Doppler blood perfusion imaging technique in the study of the effect of acupuncture and moxibustion on the entrails. In the acupunc...

Dong, Zhang; Shun-Yue, Li; Shu-You, Wang; Hui-Min, Ma

179

Critical Comparison of Hot-Wire Anemometry and Laser Doppler Velocimetry for I.C. Engine Applications.  

Science.gov (United States)

Hot-wire anemometer and laser Doppler velocimeter measurement have been taken in a motored reciprocating engine and compared to access the validity of hot-wire measurements. The procedure used to account for the sensitivity of the hot wire to changes in t...

O. P. Witze

1979-01-01

180

Laser Doppler and transcutaneous oximetry: modern investigations to assess drug efficacy in chronic venous insufficiency.  

Science.gov (United States)

During chronic venous insufficiency (CVI), microcirculatory changes, e.g. a decrease in transcutaneous oxygen pressure (tcpO2) and an increase in transcutaneous carbon dioxide pressure (tcpCO2), are implicated in the pathophysiology of trophic disorders leading ultimately to venous ulcers. Daflon 500 mg1, a micronized purified flavonoid fraction, has been shown to improve venous tone, capillary permeability and resistance, and lymphagogue activity at a daily dose of 2 tablets. To assess the effects of Daflon 500 mg on microcirculatory parameters by means of laser Doppler fluxmetry and transcutaneous oxiketry, a 3-month, double-blind, randomized, parallel-group study was carried out in 104 patients divided into 3 groups according to the daily dose: 1 tablet (group 1, n = 34), 2 tablets (group 2, n = 33), on 4 tablets (group 3, n = 37). All patients (mean age 43.7 +/- 13.1 years; 100 females, 4 males) included in the study were affected by mild CVI. They were followed for 90 days with visits at 1 month (day 28) and 3 months (day 90). At inclusion, there were no significant differences between groups as regards biometric data, mean tcpO2 (group 1, 62.7 +/- 4.5 mm Hg; group 2, 64.0 +/- 3.3 mm Hg; group 3, 64.1 +/- 3.5 mm Hg), mean tcpCO2 (group 1, 40.7 +/- 2.5 mm Hg; group 2, 39.3 +/- 2.9 mm Hg; group 3, 40.0 +/- 2.5 mm Hg) and laser Doppler parameters. Fourteen patients withdrew from the study (group 1, n = 4; group 2, n = 3; group 3, n = 7): 9 for reasons not related to treatment, 3 for adverse events, 2 because they were lost to follow-up. From day 0 to day 90, mean tcpO2 significantly increased (p Daflon 500 mg improved oximetric measurements and did not alter laser Doppler parameters. These data suggest that Daflon 500 mg, at the early stages of CVI, acts favourably on the microcirculatory disturbances also involved in the pathophysiology of more severe stages of CVI. PMID:8748889

Belcaro, G; Cesarone, M R; de Sanctis, M T; Incandela, L; Laurora, G; Février, B; Wargon, C; De Gregoris, P

1995-01-01

 
 
 
 
181

He-Ne laser effects on blood microcirculation. An in vivo study through laser doppler flowmetry; Efeito do laser de helio neonio sobre a microcirculacao sanguinea durante a reparacao tecidual. Estudo in vivo por meio de fluxometria laser doppler  

Energy Technology Data Exchange (ETDEWEB)

Blood microcirculation performs an important function in tissue repair process, as well as in pain control, allowing for greater oxygenation of the tissues and the accelerated expulsion of metabolic products, that may be contributing to pain. Low Intensity Laser Therapy (LILT) is widely used to promote healing, and there is an assumption that it is mechanism of action may be due to an enhancement of blood supply. The purpose of this study was to evaluate, using laser Doppler flowmetry (LDF), the stated effects caused by radiation emitted by a He-Ne laser ({lambda}=632.8 nm) on blood microcirculation during tissue repair. To this end, 15 male mice were selected and received a liquid nitrogen provoked lesion, above the dorsal region, and blood flow was measured periodically, during 21 days. Due to radiation emission by the LDF equipment, a control group was established to evaluate possible effects caused by this radiation on microcirculation. To evaluate the He-Ne laser effects, a 1.15 J/cm{sup 2} dose was utilized, with an intensity of 6 mW/cm{sup 2}. The results obtained demonstrate flow alterations, provoked by the lesion, and subsequent inflammatory response. There was no statistical difference between the studied groups. As per the analysis of the results there is no immediate effect due the radiation emitted by a He Ne laser on microcirculation, although a percentage increase was observed in day 7 on medium blood flow rate in irradiated specimens. New studies are necessary to validate the use of this wavelength, in order to promote beneficial alterations in blood supply in radiated areas. (author)

Nunez, Silvia Cristina

2002-07-01

182

Measurement uncertainty and temporal resolution of Doppler global velocimetry using laser frequency modulation  

International Nuclear Information System (INIS)

[en] A Doppler global velocimetry (DGV) measurement technique with a sinusoidal laser frequency modulation is presented for measuring velocity fields in fluid flows. A cesium absorption cell is used for the conversion of the Doppler shift frequency into a change in light intensity, which can be measured by a fiber coupled avalanche photo diode array. Because of a harmonic analysis of the detector element signals, no errors due to detector offset drifts occur and no reference detector array is necessary for measuring the scattered light power. Hence, large errors such as image misalignment errors and beam split errors are eliminated. Furthermore, the measurement system is also capable of achieving high measurement rates up to the modulation frequency (100 kHz) and thus opens new perspectives to multiple point investigations of instationary flows, e.g., for turbulence analysis. A fundamental measurement uncertainty analysis based on the theory of Cramer and Rao is given and validated by experimental results. The current relation between time resolution and measurement uncertainty, as well as further optimization strategies, are discussed

2008-07-20

183

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

184

Laser Doppler and transcutaneous oximetry: modern investigations to assess drug efficacy in chronic venous insufficiency.  

UK PubMed Central (United Kingdom)

During chronic venous insufficiency (CVI), microcirculatory changes, e.g. a decrease in transcutaneous oxygen pressure (tcpO2) and an increase in transcutaneous carbon dioxide pressure (tcpCO2), are implicated in the pathophysiology of trophic disorders leading ultimately to venous ulcers. Daflon 500 mg1, a micronized purified flavonoid fraction, has been shown to improve venous tone, capillary permeability and resistance, and lymphagogue activity at a daily dose of 2 tablets. To assess the effects of Daflon 500 mg on microcirculatory parameters by means of laser Doppler fluxmetry and transcutaneous oxiketry, a 3-month, double-blind, randomized, parallel-group study was carried out in 104 patients divided into 3 groups according to the daily dose: 1 tablet (group 1, n = 34), 2 tablets (group 2, n = 33), on 4 tablets (group 3, n = 37). All patients (mean age 43.7 +/- 13.1 years; 100 females, 4 males) included in the study were affected by mild CVI. They were followed for 90 days with visits at 1 month (day 28) and 3 months (day 90). At inclusion, there were no significant differences between groups as regards biometric data, mean tcpO2 (group 1, 62.7 +/- 4.5 mm Hg; group 2, 64.0 +/- 3.3 mm Hg; group 3, 64.1 +/- 3.5 mm Hg), mean tcpCO2 (group 1, 40.7 +/- 2.5 mm Hg; group 2, 39.3 +/- 2.9 mm Hg; group 3, 40.0 +/- 2.5 mm Hg) and laser Doppler parameters. Fourteen patients withdrew from the study (group 1, n = 4; group 2, n = 3; group 3, n = 7): 9 for reasons not related to treatment, 3 for adverse events, 2 because they were lost to follow-up. From day 0 to day 90, mean tcpO2 significantly increased (p < 0.001) in each group (group 1, 3.0 +/- 2.1 mm Hg; group 2, 2.9 +/- 2.1 mm Hg; group 3, 2.5 +/- 1.6 mm Hg), mean tcpCO2 significantly decreased (p < 0.001) in each group (group 1, 2.6 +/- 2.0 mm Hg; group 2, 1.7 +/- 1.9 mm Hg; group 3, 2.2 +/- 1.5 mm Hg). No significant differences were observed between groups. Laser Doppler parameters remained unchanged from day 0 to day 90 in the 3 groups. Symptoms (discomfort, pain, heaviness, burning sensation) and signs (oedema) of CVI as well as perimetric measurements of calf and supramalleolar area were significantly improved in the 3 groups. In conclusion, during this 3-month study, Daflon 500 mg improved oximetric measurements and did not alter laser Doppler parameters. These data suggest that Daflon 500 mg, at the early stages of CVI, acts favourably on the microcirculatory disturbances also involved in the pathophysiology of more severe stages of CVI.

Belcaro G; Cesarone MR; de Sanctis MT; Incandela L; Laurora G; Février B; Wargon C; De Gregoris P

1995-01-01

185

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

186

Barriers to the management of Diabetes Mellitus – is there a future role for Laser Doppler Flowmetry?  

Directory of Open Access Journals (Sweden)

Full Text Available Diabetes Mellitus (DM) is a chronic disease that carries a significant disease burden in Australia and worldwide. The aim of this paper is to identify current barriers in the management of diabetes, ascertain whether there is a benefit from early detection and determine whether LDF has the potential to reduce the disease burden of DM by reviewing the literature relating to its current uses and development. In this literature review search terms included; laser Doppler flowmetry, diabetes mellitus, barriers to management, uses, future, applications, vasomotion, subcutaneous, cost. Databases used included Google Scholar, Scopus, Science Direct and Medline. Publications from the Australian government and textbooks were also utilised. Articles reviewed had access to the full text and were in English.

Minnie Au; Stephen Rattigan

2012-01-01

187

Basic Study for the fabrication of Laser Doppler Vibrometer for the Detection of Ultrasonic  

Energy Technology Data Exchange (ETDEWEB)

In order to detect the ultrasonic that is generated by the partial discharge of the heavy electric machinery, a Laser Doppler Vibrometer (LDV) is developed. A Michelson type interferometer which employed heterodyne signal process technique is built to measure the frequency and amplitude of vibration. The output signal of the fast photodetector is a frequency modulated signal centered at 40MHz. The signal from the detector is amplified and converted to intermediate frequency centered at 1 MHz after mixing process. The voltage output that is proportional to the velocity of the moving surface(PZT) is obtained using PLL. The spectrum of the FM signal is introduced to obtain amplitude information. The LDV can be used to measure the vibration of MEMS devices, automobiles, HDD and CDP. (author). 4 refs., 4 figs.

Kim, Myoungsun; Kim, Seung Jong; Kim, Ho Seong [Chung-Ang University (Korea)

2000-07-01

188

EURISOL-DS Multi-MW Target: Cavitations detection by the a Laser Doppler Vibrometer  

CERN Multimedia

This technical note summarises the innovative measurement devices used within Task #2 of the European Isotope Separation On-Line Radioactive Ion Beam Facility Design Study (EURISOL-DS) to detect the occurrence of cavitation in liquid metal flowing inside the CGS target mock-up.During the METEX hydraulic experiment carried out at IPUL (Institute of Physics of the University of Latvia), a Laser Doppler Vibrometer was used to characterize the wall vibrations of the beam window at different flow regimes. A series of tests proved the high sensitivity of the LDV to detect the occurrence of cavitation in the liquid metal flowing inside the target. In this context, a dedicated test procedure was developed to establish the validity of using LDV for detecting the onset of cavitation.

Cyril Kharoua, Yacine Kadi, Jacques Lettry, Laure Blumenfeld, Karel Samec (CERN)Knud Thomsen, Sergej Dementevjs, Rade Milenkovich (PSI)Anatoli Zik, Erik Platacis (IPUL)

189

Measurement of acoustic streaming in a closed-loop traveling wave resonator using laser Doppler velocimetry.  

Science.gov (United States)

This paper deals with the measurement of acoustic particle velocity and acoustic streaming velocity in a closed-loop waveguide in which a resonant traveling acoustic wave is sustained by two loudspeakers appropriately controlled in phase and amplitude. An analytical model of the acoustic field and a theoretical estimate of the acoustic streaming are presented. The measurement of acoustic and acoustic streaming velocities is performed using laser Doppler velocimetry. The experimental results obtained show that the curvature of the resonator impacts the acoustic velocity and the profile of acoustic streaming. The quadratic dependence of the acoustic streaming velocity on the acoustic pressure amplitude is verified and the measured cross-sectional average streaming velocity is in good agreement with the value predicted by the theoretical estimate. PMID:19894797

Desjouy, Cyril; Penelet, Guillaume; Lotton, Pierrick; Blondeau, James

2009-11-01

190

Measurement of fluid velocity development in laminar pipe flow using laser Doppler velocimetry  

International Nuclear Information System (INIS)

[en] In this paper we present a non-intrusive experimental approach for obtaining velocity gradient profiles in a transparent smooth pipe under laminar flow conditions (Re = 925) using a laser Doppler velocimeter (LDV). Measurements were taken within the entrance region of the pipe at l = 300 mm and l = 600 mm from the pipe inlet, in addition to measurements of the fully developed flow at l = 1800 mm. The obtained results show how the velocity profile from upstream of the pipe develops into a classical laminar profile downstream, which matches the theoretical profile well. Additionally, a brief summary of historical information about the development of flow measurement techniques, in particular LDV, is provided. (paper)

2013-01-01

191

Flow characteristics in spacer grids measured by rod-embedded fiber laser doppler velocimetry  

International Nuclear Information System (INIS)

[en] Precise measurement of velocity in fuel bundles is required to improve the thermal-hydraulic properties of Pressurized Water Reactor (PWR) spacer grids. To better understand the cross-flow characteristics in rod bundles for developing spacer grids, we used the rod-embedded fiber laser Doppler velocimetry (rod LDV) to measure the flow velocities inside the spacer grid flow channels. As the result of measurement, we found that the flow distribution inside the spacer grid depends on the local flow resistance of the grid straps and is clearly affected by the presence of a mixing vane. We also clarified the relationship between cross-flow velocity in the fuel bundle downstream of the spacer grid and the axial flow inside the spacer grid. (author)

2007-01-01

192

Measurement of acoustic streaming in a closed-loop traveling wave resonator using laser Doppler velocimetry.  

UK PubMed Central (United Kingdom)

This paper deals with the measurement of acoustic particle velocity and acoustic streaming velocity in a closed-loop waveguide in which a resonant traveling acoustic wave is sustained by two loudspeakers appropriately controlled in phase and amplitude. An analytical model of the acoustic field and a theoretical estimate of the acoustic streaming are presented. The measurement of acoustic and acoustic streaming velocities is performed using laser Doppler velocimetry. The experimental results obtained show that the curvature of the resonator impacts the acoustic velocity and the profile of acoustic streaming. The quadratic dependence of the acoustic streaming velocity on the acoustic pressure amplitude is verified and the measured cross-sectional average streaming velocity is in good agreement with the value predicted by the theoretical estimate.

Desjouy C; Penelet G; Lotton P; Blondeau J

2009-11-01

193

Wavelet series method for reconstruction and spectral estimation of laser Doppler velocimetry data  

Science.gov (United States)

Many techniques have been developed in order to obtain spectral density function from randomly sampled data, such as the computation of a slotted autocovariance function. Nevertheless, one may be interested in obtaining more information from laser Doppler signals than a spectral content, using more or less complex computations that can be easily conducted with an evenly sampled signal. That is the reason why reconstructing an evenly sampled signal from the original LDV data is of interest. The ability of a wavelet-based technique to reconstruct the signal with respect to statistical properties of the original one is explored, and spectral content of the reconstructed signal is given and compared with estimated spectral density function obtained through classical slotting technique. Furthermore, LDV signals taken from a screeching jet are reconstructed in order to perform spectral and bispectral analysis, showing the ability of the technique in recovering accurate information's with only few LDV samples.

Jaunet, Vincent; Collin, Erwan; Bonnet, Jean-Paul

2012-01-01

194

Innovative technique for field calibration and inspection of large district heating meters. Laser doppler velocimetry (LDV)  

Energy Technology Data Exchange (ETDEWEB)

During the last three years, the Danish Technological Institute has managed and co-ordinated a recently completed R and D project aimed at developing an innovative method for field calibration and inspection of large district heating meters. The method is based on Laser Doppler Velocimetry (LDV) and the project has been carried out in close co-operation with partners from Danish district heating plants and supply companies, flow meter manufacturers, a leading manufacturer of LDV equipment and the Technical University of Denmark. The resulting measurement method has been developed with special reference to large (>200 mm diameter) district heating meters used for surveillance, control and billing, but the technique can also be used advantageously for flow measurements in almost any closed pipe system transporting transparent gases and liquids. Results of the project have been very satisfactory and the Danish Technological Institute expects to be able to offer fully accredited in-situ LDV measurements in the near future. (orig.)

Adams, M.; Frederiksen, J.; Drysdale, A. [Danish Technological Inst., Aarhus (Denmark); Hessel, C.E. [Aalborg Municipal Works (Denmark)

2002-10-01

195

Near-exit flow-field investigation in an inducer including laser-Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

The flow field was measured near the exit of an axial-flow spiral-inducer pump impeller at design and off-design conditions. Laser-Doppler velocimetry was employed to define the blade-to-blade velocity distribution inside and outside the rotating impeller passage near the trailing edge. The observed variation of velocity and flow angle revealed a strong secondary flow, of a double vortex form, at the design flow rate and a developing hub separation zone at lower flow rates. The observed rearrangement of the flow field between the closely spaced locations upstream and downstream of the trailing edge is believed to be linked to the developing recirculation zone. Distributed deviation angles are presented for the design flow rate and overall values for all flow rates. 8 refs.

Howard, J.H.G.; Atif, A. (Waterloo Univ. (Canada))

1993-03-01

196

Doppler cooling with coherent trains of laser pulses and tunable "velocity comb"  

CERN Document Server

We explore the possibility of decelerating and Doppler cooling an ensemble of two-level atoms by a coherent train of short, non-overlapping laser pulses. We develop an analytical model for treating the dynamic of a two-level system interacting with the resulting frequency comb field by using delta-function pulses. Supporting numerical calculations were carried out to verify the predictions of the model. We find that the radiative force mimics the underlying frequency comb structure. The force pattern depends strongly on the ratio of atomic lifetime to the repetition time and also on pulse area. For example, in the limit of short lifetimes or $\\pi$-pulses the frequency peaks of the radiative force wash out. We derive analytical expressions for the radiative force and for optimal parameters of the pulse train and study compression of velocity distribution.

Ilinova, Ekaterina; Derevianko, Andrei

2011-01-01

197

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

198

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

Energy Technology Data Exchange (ETDEWEB)

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 {lambda}{sub {omega}} = 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, {lambda}-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.)

Kim, Jae-Ihn

2009-07-23

199

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 m 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.)

2009-01-01

200

High-range-resolution velocity-estimation techniques for coherent Doppler lidars with exponentially shaped laser pulses.  

UK PubMed Central (United Kingdom)

On the basis of an analysis of the autocovariance of the complex heterodyne signal, some novel algorithms are derived and investigated for recovering the nonuniform Doppler-velocity coherent-lidar profiles within the lidar resolution interval conditioned by the sensing laser-pulse length. The case of exponentially shaped sensing laser pulses is considered. The algorithm performance and efficiency are studied and illustrated by computer simulations (based on the use of pulse models and real laser pulses), taking into account the influence of additive noise and radial-velocity fluctuations. It is shown that, at some reasonable number of signal realizations used and with appropriate data processing to suppress the noise effects, the Doppler-velocity profiles can be determined with a considerably shorter resolution interval in comparison with that (usually accepted as a lower bound) determined by the pulse length.

Gurdev LL; Dreischuh TN; Stoyanov DV

2002-03-01

 
 
 
 
201

Laser Doppler velocimetry measurements in coaxial, co- and counter-swirling, isothermal jets  

Energy Technology Data Exchange (ETDEWEB)

Measured values of the three components of mean velocity and the six components of the turbulent stress tensor are reported in free, co-axial, isothermal, co- and counter-swirling jet flows representative of combustor flows. The effects of specific radial distributions of mean swirl velocity, and co- and counter-swirling annular flows on the flow field are investigated. A one-dimensional laser Doppler velocimeter is used to obtain the measurements. It consists of a 15mW He-Ne laser, DISA 55x modular optics with a Bragg cell and electronic frequency shifting to handle high turbulence intensities and reverse flow regions, and a TSI model 1980A counter processor. Measured values are presented for two tangential velocity profiles in co- and counter-swirling annular flows, in all, for four different cases. A central recirculation zone occurs in each case. Streamlines are calculated from the measured velocity distribution, and contours of turbulent kinetic energy are presented. The former show the structure of the CRZ, and the latter indicate the zones of high turbulence intensity. Experimental data indicate that the flows are more affected by the direction of rotation of the annular flow than by altering the radial distribution of mean swirl velocity. Counter-swirl tends to increase the turbulent stresses with the maxima occuring near the boundary of the CRZ.

Robinson, P.A.; Cusworth, R.A.; Sislian, J.P.

1986-05-01

202

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

203

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

204

Broadband measurement of translational and angular vibrations using a single continuously scanning laser Doppler vibrometer.  

UK PubMed Central (United Kingdom)

A continuous scanning laser Doppler velocimetry (CSLDV) technique is used to measure the low frequency broadband vibrations associated with human skeletal muscle vibrations (typically f < 100 Hz) by continuously varying the orientation of laser beam over distances that are short compared to the characteristic wavelengths of the vibrations. The high frequency scan (compared to the vibration frequency) enables the detection of broadband translational and angular velocities at a single point using amplitude demodulation of the CSDLV signal. For instance, linear scans allow measurement of the normal surface velocity and one component of angular velocity vector, while circular scans allow measurement of an additional angular velocity component. This CSLDV technique is first validated here using gel samples mimicking soft tissues and then applied to measure multiple degrees of freedom (DOF) of a subject's hand exhibiting fatigue-induced tremor. Hence this CSLDV technique potentially provides a means for measuring multiple DOF of small human body parts (e.g., fingers, tendons, small muscles) for various applications (e.g., haptic technology, remote surgery) when the use of skin-mounted sensors (e.g. accelerometers) can be problematic due to mass-loading artifacts or tethering issues.

Salman M; Sabra KG

2012-09-01

205

Broadband measurement of translational and angular vibrations using a single continuously scanning laser Doppler vibrometer.  

Science.gov (United States)

A continuous scanning laser Doppler velocimetry (CSLDV) technique is used to measure the low frequency broadband vibrations associated with human skeletal muscle vibrations (typically f < 100 Hz) by continuously varying the orientation of laser beam over distances that are short compared to the characteristic wavelengths of the vibrations. The high frequency scan (compared to the vibration frequency) enables the detection of broadband translational and angular velocities at a single point using amplitude demodulation of the CSDLV signal. For instance, linear scans allow measurement of the normal surface velocity and one component of angular velocity vector, while circular scans allow measurement of an additional angular velocity component. This CSLDV technique is first validated here using gel samples mimicking soft tissues and then applied to measure multiple degrees of freedom (DOF) of a subject's hand exhibiting fatigue-induced tremor. Hence this CSLDV technique potentially provides a means for measuring multiple DOF of small human body parts (e.g., fingers, tendons, small muscles) for various applications (e.g., haptic technology, remote surgery) when the use of skin-mounted sensors (e.g. accelerometers) can be problematic due to mass-loading artifacts or tethering issues. PMID:22978867

Salman, Muhammad; Sabra, Karim G

2012-09-01

206

Field performance of an all-semiconductor laser coherent Doppler lidar.  

UK PubMed Central (United Kingdom)

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 PJ; Pedersen C

2012-06-01

207

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

International Nuclear Information System (INIS)

[en] 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

2008-09-20

208

Skin blood flow from gas transport: helium xenon and laser Doppler compared  

Energy Technology Data Exchange (ETDEWEB)

A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics.

Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

1988-03-01

209

Testresults KROHNE 8-inch ultrasonic flowmeter  

Energy Technology Data Exchange (ETDEWEB)

A new development in the field of ultrasonic liquid flowmeasurements has been achieved with the multichannel liquid ultrasonic flowmeter; the first for use in maintenance-free custody transfer applications. Although ultrasonic flowmeters are used for applications in the oil industry for many years, this new development will have a big impact on custody transfer flow measurement. Not only because of the compactness, but also because of the low investment and operating cost of this flowmeter. This paper describes the system and the method of operation as well as practical experiences and achieved test results of this flowmeter. (author)

Boer, A.H.; Volmer, W.

1997-07-01

210

A simulation environment for assisting system design of coherent laser doppler wind sensor for active wind turbine pitch control  

Science.gov (United States)

In order to assist a system design of laser coherent Doppler wind sensor for active pitch control of wind turbine systems (WTS), we developed a numerical simulation environment for modeling and simulation of the sensor system. In this paper we present this simulation concept. In previous works, we have shown the general idea and the possibility of using a low cost coherent laser Doppler wind sensing system for an active pitch control of WTS in order to achieve a reduced mechanical stress, increase the WTS lifetime and therefore reduce the electricity price from wind energy. Such a system is based on a 1.55?m Continuous-Wave (CW) laser plus an erbium-doped fiber amplifier (EDFA) with an output power of 1W. Within this system, an optical coherent detection method is chosen for the Doppler frequency measurement in megahertz range. A comparatively low cost short coherent length laser with a fiber delay line is used for achieving a multiple range measurement. In this paper, we show the current results on the improvement of our simulation by applying a Monte Carlo random generation method for positioning the random particles in atmosphere and extend the simulation to the entire beam penetrated space by introducing a cylindrical co-ordinate concept and meshing the entire volume into small elements in order to achieve a faster calculation and gain more realistic simulation result. In addition, by applying different atmospheric parameters, such as particle sizes and distributions, we can simulate different weather and wind situations.

Shinohara, Leilei; Pham Tran, Tuan Anh; Beuth, Thorsten; Umesh Babu, Harsha; Heussner, Nico; Bogatscher, Siegwart; Danilova, Svetlana; Stork, Wilhelm

2013-05-01

211

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

International Nuclear Information System (INIS)

[en] 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 ?1, 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.

2011-12-21

212

Single-point relative process using Laser-Doppler velocimetry for calibration of flow sensors at temperatures above 100 C  

International Nuclear Information System (INIS)

[en] Due to technical difficulties, the calibration of flow sensors of heat meters above 100 C cannot be performed by the gravimetric standard method. A novel method using a laser Doppler velocimeter (LDV) was therefore developed, based on the gravimetric method below 100 C and on Reynolds' similarity law. This method allows a turbine meter to be calibrated as a secondary flowrate standard with a relative uncertainty below 0,2% for temperatures of up to 180 C. (orig.)[de] Zur Kalibrierung hydraulischer Geber von Waermezaehlern oberhalb von 100 C wird das gravimetrische Standardverfahren wegen zu grosser technischer Schwierigkeiten nicht angewendet. Deshalb wurde ein neuartiges Einpunkt-Relativverfahren mit einem Laser-Doppler-Velozimeter (LDV) entwickelt, das einerseits auf dem gravimetrischen Verfahren unterhalb von 100 C und andererseits auf dem Reynoldsschen-Aehnlichkeitsgesetz beruht. Auf diese Weise liess sich ein Turbinenradzaehler fuer Temperaturen bis 180 C mit relativen Messunsicherheiten unter 0,2% als Sekundaernormal fuer die Volumenstromskala kalibrieren. (orig.)

1996-01-01

213

The correlation between three methods of skin perfusion pressure measurement: radionuclide washout, laser Doppler flow, and photoplethysmography.  

Science.gov (United States)

The most accurate measurement of skin perfusion pressure is made with use of radioisotopic clearance techniques. We compared the skin perfusion pressure using radioisotope to the skin perfusion pressure measured simultaneously by placing laser Doppler and photoplethysmography probes within a transparent polyvinylchloride plastic blood pressure cuff in 13 subjects. A new device, which was created for this experiment, consisted of a plastic bladder into which light-emitting probes can be placed, so that the pressure applied to the skin was transmitted by the surface of the bladder, rather than by the surface of a rigid probe. The cuff was inflated to a supra-systolic pressure over the intradermal injection site of technetium Tc 99m, then deflated in 10 mm Hg decrements at 3-minute intervals. The pressures at which radioisotope clearance began, at which microcirculatory flow was detected by laser Doppler, and at which deflection of the photoplethysmography (DC mode) output occurred, were recorded as the skin perfusion pressure. The range of radioisotopic determined skin perfusion pressure was 0 to 100; skin perfusion pressure-laser Doppler was 0 to 100; and skin perfusion pressure-photoplethysmography was 60 to 100, with 7 of 13 limbs demonstrating no clear deflection point and thus an unobtainable skin perfusion pressure-photoplethysmography reading. Linear regression revealed a coefficient of correlation of 0.991 for skin perfusion pressure when the radioisotopic and laser Doppler methods were compared. Our study is not in agreement with previous reports of the successful determination of skin perfusion pressure with use of photoplethysmography. This may be due to differences in our technique when compared with previous reports of skin perfusion pressure-photoplethysmography determination.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1578538

Malvezzi, L; Castronuovo, J J; Swayne, L C; Cone, D; Trivino, J Z

1992-05-01

214

The correlation between three methods of skin perfusion pressure measurement: radionuclide washout, laser Doppler flow, and photoplethysmography.  

UK PubMed Central (United Kingdom)

The most accurate measurement of skin perfusion pressure is made with use of radioisotopic clearance techniques. We compared the skin perfusion pressure using radioisotope to the skin perfusion pressure measured simultaneously by placing laser Doppler and photoplethysmography probes within a transparent polyvinylchloride plastic blood pressure cuff in 13 subjects. A new device, which was created for this experiment, consisted of a plastic bladder into which light-emitting probes can be placed, so that the pressure applied to the skin was transmitted by the surface of the bladder, rather than by the surface of a rigid probe. The cuff was inflated to a supra-systolic pressure over the intradermal injection site of technetium Tc 99m, then deflated in 10 mm Hg decrements at 3-minute intervals. The pressures at which radioisotope clearance began, at which microcirculatory flow was detected by laser Doppler, and at which deflection of the photoplethysmography (DC mode) output occurred, were recorded as the skin perfusion pressure. The range of radioisotopic determined skin perfusion pressure was 0 to 100; skin perfusion pressure-laser Doppler was 0 to 100; and skin perfusion pressure-photoplethysmography was 60 to 100, with 7 of 13 limbs demonstrating no clear deflection point and thus an unobtainable skin perfusion pressure-photoplethysmography reading. Linear regression revealed a coefficient of correlation of 0.991 for skin perfusion pressure when the radioisotopic and laser Doppler methods were compared. Our study is not in agreement with previous reports of the successful determination of skin perfusion pressure with use of photoplethysmography. This may be due to differences in our technique when compared with previous reports of skin perfusion pressure-photoplethysmography determination.(ABSTRACT TRUNCATED AT 250 WORDS)

Malvezzi L; Castronuovo JJ Jr; Swayne LC; Cone D; Trivino JZ

1992-05-01

215

Material properties identification using ultrasonic waves and laser Doppler vibrometer measurements: a multi-input multi-output approach  

Science.gov (United States)

In this paper a multi-input multi-output approach able to determine the material properties of homogeneous materials is presented. To do so, an experimental set-up which combines the use of multi harmonic signals with interleaved frequencies and laser Doppler vibrometer measurements has been developed. A modeling technique, based on transmission and reflection measurements, allowed the simultaneous determination of longitudinal wave velocity, density and thickness of the materials under test with high levels of precision and accuracy.

Longo, R.; Vanlanduit, S.; Guillaume, P.

2013-10-01

216

Measurement of flow velocities in a model of blood vessel by laser doppler anemometer (1D LDA)  

International Nuclear Information System (INIS)

[en] In this paper results of measuring velocities in a simple profile by laser doppler anemometer (1D LDA) are presented. Further work on the project will include research in models of normal and changed configurations related to human pathology. The profile of flow velocities and level of turbulence are determined for a cylindrical tube with 18 mm diameter, which approximately presents an usual radius of aorta. (author)

1995-01-01

217

Laser-Doppler acoustic probing of granular media with in-depth property gradient and varying pore pressures  

International Nuclear Information System (INIS)

Non-contacting ultrasonic techniques recently proved to be efficient in the physical modeling of seismic-wave propagation at various application scales, as for instance in the context of geological analogue and seismic modeling. An innovative experimental set-up is proposed here to perform laser-Doppler acoustic probing of unconsolidated granular media with varying pore pressures. The preliminary experiments presented here provide reproducible results and exploitable data, thus validating both the proposed medium preparation and pressure gradient generation procedure.

2012-05-24

218

Evaluation of a dual beam laser Doppler displacement meter retrofitted to a coordinate measuring machine. Final report  

Energy Technology Data Exchange (ETDEWEB)

A dual beam laser Doppler displacement measuring system was mounted to a fixed-table, cantilever-type coordinate measuring machine (CMM) to establish the feasibility of real time angular error correction for each CMM axis. The performance improvement was evaluated relative to the CMM`s standard scales. The dual beam system proved to have no advantage over a single beam laser due to an inability to measure the actual angular errors at the probe location, but showed potential for substantial accuracy improvement over the standard CMM scales when geometry errors were software corrected.

Ramsdale, S.J.; Hanshaw, R.A.

1997-05-01

219

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

220

In-field use of laser Doppler vibrometer on a wind turbine blade  

Energy Technology Data Exchange (ETDEWEB)

One of our primary goals was to determine how well a laser Doppler vibrometer (LDV) could measure the structural dynamic response of a wind turbine that was parked in the field. We performed a series of preliminary tests in the lab to determine the basic limitations of the LDV for this application. We then instrumented an installed parked horizontal axis wind turbine with accelerometers to determine the natural frequencies, damping, and mode shapes of the wind turbine and rotor as a baseline for the LDV and our other tests. We also wanted to determine if LDV modal information could be obtained from a naturally (wind) excited wind turbine. We compared concurrently obtained accelerometer and LDV data in an attempt to assess the quality of the LDV data. Our test results indicate the LDV can be successfully used in the field environment of an installed wind turbine, but with a few restrictions. We were successful in obtaining modal information from a naturally (wind) excited wind turbine in the field, but the data analysis requires a large number of averaged data sets to obtain reasonable results. An ultimate goal of this continuing project is to develop a technique that will monitor the health of a structure, detect damage, and hopefully predict an impending component failure.

Rumsey, M.; Hurtado, J.; Hansche, B. [and others

1998-12-31

 
 
 
 
221

The photo-electric current in laser-Doppler flowmetry by Monte Carlo simulations  

International Nuclear Information System (INIS)

[en] Monte Carlo (MC) simulations significantly contributed to a better understanding of laser-Doppler flowmetry (LDF). Here it is shown that the data obtained from standard MC simulations can be reinterpreted and used to extract more information such as the photo-electric current (i(t)). This is important because i(t) is the starting point for evaluating any existing or new algorithm to be used in LDF instrumentation. This circumvents the tedious procedure of generating a specific model (often approximated if possible at all) each time a different algorithm is considered. By a series of tutorial examples, the influence of various parameters is investigated, e.g. sampling rate, total acquisition time and dc filtering. These cases also demonstrate the fundamental role played by the photons' random phase in the shaping of the LDF signal. In particular, it is demonstrated by MC simulation that when the number of photon-moving red blood cell interactions is too low, then the Siegert relation that exists between the field and photo-electric current autocorrelation functions does not hold. This is an important point because the validity of the Siegert relation is implicitly admitted in the majority of the classical analytical models for the autocorrelation function in LDF (the classical MC approach does not allow one to study this problem). The proposed method and examples could stimulate new ideas and help the scientific community develop, test and validate new approaches in LDF. (note)

2009-07-21

222

Laser Doppler imaging for assessment of microcirculation in juvenile systemic sclerosis.  

UK PubMed Central (United Kingdom)

Objectives. The objectives of this study were to evaluate the dynamic behaviour of digital skin microvascular blood flow before and after cold stimulation using laser Doppler imaging (LDI) in children and adolescents with RP secondary to juvenile systemic sclerosis (JSS), primary RP (PRP) and healthy controls and to compare functional abnormalities measured by LDI with structural microvascular abnormalities evaluated by nailfold capillaroscopy (NFC).Methods. Five JSS patients, five children and adolescents with PRP and five healthy controls matched for gender and age were included. All subjects had NFC performed. Finger blood flow (FBF) was measured using the LDI system (Moor Instruments) at baseline and after cold stimulus (CS).Results. There were a decreased number of capillaries, a greater number of enlarged capillaries and a higher deletion score in JSS patients compared with controls and patients with PRP. The mean baseline FBF was significantly lower in JSS patients compared with controls. There was no difference between the mean baseline FBF in JSS patients compared with patients with PRP. There was a significant decrease in FBF 1 min after CS in all groups followed by blood flow recovery at 20 min after CS in comparison with basal FBF values in controls, but not in JSS and PRP patients.Conclusion. In JSS patients, LDI showed a lower FBF before and after CS compared with healthy controls and may be an objective and sensitive method for the measurement of digital skin blood flow in RP children.

Piotto DG; Correa MJ; Miotto E Silva VB; Kayser C; Terreri MT

2013-09-01

223

Physiological effects of indomethacin and celecobix: an S-transform laser Doppler flowmetry signal analysis  

Energy Technology Data Exchange (ETDEWEB)

Conventional signal processing typically involves frequency selective techniques which are highly inadequate for nonstationary signals. In this paper, we present an approach to perform time-frequency selective processing of laser Doppler flowmetry (LDF) signals using the S-transform. The approach is motivated by the excellent localization, in both time and frequency, afforded by the wavelet basis functions. Suitably chosen Gaussian wavelet functions are used to characterize the subspace of signals that have a given localized time-frequency support, thus enabling a time-frequency partitioning of signals. In this paper, the goal is to study the influence of various pharmacological substances taken by the oral way (celecobix (Celebrex (registered) ), indomethacin (Indocid (registered) ) and placebo) on the physiological activity behaviour. The results show that no statistical differences are observed in the energy computed from the time-frequency representation of LDF signals, for the myogenic, neurogenic and endothelial related metabolic activities between Celebrex and placebo, and Indocid and placebo. The work therefore proves that these drugs do not affect these physiological activities. For future physiological studies, there will therefore be no need to exclude patients having taken cyclo-oxygenase 1 inhibitions.

Assous, S [Groupe ISAIP-ESAIP, 18, rue du 8 mai 1945, BP 80022, 49180 Saint Barthelemy d' Anjou Cedex (France); Humeau, A [Groupe ISAIP-ESAIP, 18, rue du 8 mai 1945, BP 80022, 49180 Saint Barthelemy d' Anjou Cedex (France); Tartas, M [Laboratoire de Physiologie et d' Explorations Vasculaires, Centre Hospitalier Universitaire d' Angers, 49033 Angers Cedex 01 (France); Abraham, P [Laboratoire de Physiologie et d' Explorations Vasculaires, Centre Hospitalier Universitaire d' Angers, 49033 Angers Cedex 01 (France); L' Huillier, J P [Ecole Nationale Superieure d' Arts et Metiers (ENSAM), Laboratoire Procedes Materiaux Instrumentation (LPMI), 2, boulevard du Ronceray, BP 3525, 49035 Angers Cedex (France)

2005-05-07

224

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

UK PubMed Central (United Kingdom)

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

Ku DN; Giddens DP

1987-01-01

225

The usefulness of a laser Doppler in the measurement of toe blood pressures.  

UK PubMed Central (United Kingdom)

OBJECTIVE: The purpose of this study was to evaluate the clinical value and reproducibility of laser Doppler (LD) versus photoplethysmography (PPG) in the measurement of the systolic toe blood pressure. METHODS: Toe blood pressure was measured in 60 patients in different stages of peripheral vascular disease with simultaneous digital sampling of PPG and two LD signals, each with a different filter setting (3 second [LD(3)] and 0.03 second [LD(0.03)]), and cuff pressure. These measurements were repeated after 1 week. The signals were analyzed with previous results ignored. The agreement of the PPG and LD pressures and reproducibility after 1 week were assessed by calculating the intraclass correlation coefficient (ICC). The agreement variation across the range of pressure values was visually explored by means of difference plots. RESULTS: In 19 legs with a very low pressure only LD could adequately measure the pressure, whereas PPG did not. The ICCs between PPG and LD(3) and LD(0.03) were 0.95 or more. The ICCs of the 1-week reproducibility of the PPG, LD(3), and LD(0.03) pressures were 0.92, 0.88, and 0.86, respectively. The variation was equally distributed across the range of pressures in all three methods. CONCLUSION: LD is a reliable alternative to PPG to measure toe blood pressures. Furthermore, LD is able to measure low pressures, which is relevant in the assessment of the presence of critical ischemia.

de Graaff JC; Ubbink DT; Legemate DA; de Haan RJ; Jacobs MJ

2000-12-01

226

The effect of intranasal budesonide spray on mucosal blood flow measured with laser Doppler flowmetry.  

UK PubMed Central (United Kingdom)

BACKGROUND: Recent reports have shown that, although rare, findings of mucosal ulcers and perforations of the nasal septum in some cases may be associated with the use of topical nasal glucocorticosteroids (GCS). It can been speculated that, a reduction in septal mucosal blood flow causing ischemia may eventually induce septal perforations. AIM: To evaluate whether a single dose of a potent nasal GCS given in a clinically recommended dose may acutely reduce the mucosal blood flow on the nasal septum. METHODS: Six healthy subjects received in a randomised double blind placebo controlled crossover procedure one dose of 64 micrograms budesonide aqueous nasal spray (Rhinocort aqua, AstraZeneca R&D, Lund, Sweden) and placebo. One dose was delivered into each nasal cavity by means of a pump spray. As a positive control 140 micrograms of xylometazoline (Nezeril, AstraZeneca R&D, Lund, Sweden) was sprayed in the same way, but in an open fashion. A wash-out period of at least 3 days followed each session. Blood flow was measured on the nasal septum with Laser Doppler flowmetry up to 20 min after administration. RESULTS: Budesonide did not affect the nasal septal mucosal blood flow as compared to placebo, but xylometazoline reduced the septal mucosal blood flow by 60.9 +/- 7.1% measured from baseline values. CONCLUSION: A single dose of intranasal budesonide aqueous nasal spray has no acute effects on nasal septal mucosal blood flow.

Cervin A; Akerlund A; Greiff L; Andersson M

2001-03-01

227

Multiscale analysis of microvascular blood flow: a multiscale entropy study of laser Doppler flowmetry time series.  

Science.gov (United States)

Processes regulating the cardiovascular system (CVS) are numerous. Each possesses several temporal scales. Their interactions lead to interdependences across multiple scales. For the CVS analysis, different multiscale studies have been proposed, mostly performed on heart rate variability signals (HRV) reflecting the central CVS; only few were dedicated to data from the peripheral CVS, such as laser Doppler flowmetry (LDF) signals. Very recently, a study implemented the first computation of multiscale entropy for LDF signals. A nonmonotonic evolution of multiscale entropy with two distinctive scales was reported, leading to a markedly different behavior from the one of HRV. Our goal herein is to confirm these results and to go forward in the investigations on origins of this behavior. For this purpose, 12 LDF signals recorded simultaneously on the two forearms of six healthy subjects are processed. This is performed before and after application of physiological scales-based filters aiming at isolating previously found frequency bands linked to physiological activities. The results obtained with signals recorded simultaneously on two different sites of each subject show a probable central origin for the nonmonotonic behavior. The filtering results lead to the suggestion that origins of the distinctive scales could be dominated by the cardiac activity. PMID:21712149

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

2011-06-27

228

Multiscale analysis of microvascular blood flow: a multiscale entropy study of laser Doppler flowmetry time series.  

UK PubMed Central (United Kingdom)

Processes regulating the cardiovascular system (CVS) are numerous. Each possesses several temporal scales. Their interactions lead to interdependences across multiple scales. For the CVS analysis, different multiscale studies have been proposed, mostly performed on heart rate variability signals (HRV) reflecting the central CVS; only few were dedicated to data from the peripheral CVS, such as laser Doppler flowmetry (LDF) signals. Very recently, a study implemented the first computation of multiscale entropy for LDF signals. A nonmonotonic evolution of multiscale entropy with two distinctive scales was reported, leading to a markedly different behavior from the one of HRV. Our goal herein is to confirm these results and to go forward in the investigations on origins of this behavior. For this purpose, 12 LDF signals recorded simultaneously on the two forearms of six healthy subjects are processed. This is performed before and after application of physiological scales-based filters aiming at isolating previously found frequency bands linked to physiological activities. The results obtained with signals recorded simultaneously on two different sites of each subject show a probable central origin for the nonmonotonic behavior. The filtering results lead to the suggestion that origins of the distinctive scales could be dominated by the cardiac activity.

Humeau A; Mahé G; Chapeau-Blondeau F; Rousseau D; Abraham P

2011-10-01

229

CHARACTERIZATION OF AIRFLOWS NEAR THE EXIT OF HVAC REGISTERS USING LASER DOPPLER VELOCIMETRY (LDV).  

Energy Technology Data Exchange (ETDEWEB)

A facility to characterize the airflow at the exit of HVAC registers was designed and fabricated. The objective of this work is to obtain velocity and turbulence data at the exit of registers, which can then be used as an input boundary condition in a modern Computational Fluid Dynamics (CFD) code to predict the velocity and temperature distribution in an enclosure, and also the register performance parameters such as throw. During the course of this work, two commonly used registers were tested. Both registers were 8 inch x 4 inch sidewall registers. Laser Doppler Velocimetry was used to measure the axial and vertical components of the velocity vector at various locations across the face of the registers. For the two cases of registers studied here, the results suggest that the velocity field at the very exit of each of these registers scales with the flow rate through the registers. This means that, in the mode of operation in which the supply fan (of an HVAC system) has a ''High'' and ''Low'' setting, similar velocity scaling would result for the type of registers tested here.

TUTU,N.K.; KRISHNA,C.R.; ANDREWS,J.W.; BUTCHER,T.A.

2003-03-13

230

Measurement of velocities in gas-liquid two-phase flow using Laser Doppler Velocimetry  

Energy Technology Data Exchange (ETDEWEB)

Measurements of bubble and liquid velocities in two-phase flow have been made using a new forward/backward scattering Laser Doppler Velocimetry (LDV) technique. This work was performed in a 6.4 by 11.1 mm vertical duct using known air/water mixtures. A standard LDV fiber optic probe was used to measure the bubble velocity, using direct backscattered light. A novel retro-reflector and lens assembly permitted the same probe to measure the liquid velocity with direct forward-scattered light. The bubble velocity was confirmed by independent measurements with a high-speed video system. The liquid velocity was confirmed by demonstrating the dominance of the liquid seed data rate in the forward-scatter measurement. Experimental data are presented to demonstrate the accuracy of the technique for a wide range of flow conditions, from bubbles as small as 0.75-mm-diam to slugs as large as 10-mm wide by 30-mm long. In the slug regime, the LDV technique performed velocity measurements for both phases, for void fractions up to 50%, which was the upper limit of our experimental investigation.

Vassallo, P.F.; Trabold, T.A.; Moore, W.E.; Kirouac, G.J.

1992-09-01

231

Spatial structure of a confined swirling flow using planar elastic scatter imaging and laser Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

This paper reports the results of a study of the instantaneous spatial structure of a confined swirling flow after a sudden expansion. The flow chosen corresponds to the cold flow conditions of an axisymmetric laboratory-scale research furnace. The swirl number of the flow is 0.7 at the inlet plane and the expansion diameter ratio is 6:1. The flow has a centre hub-to-throat diameter ratio of 1:4. Data are reported for the instantaneous spatial structure of the flow via transient planar elastic scattering imaging. This technique allows for unambiguous visualization of the spatial structure of the flow by slicing through it with a thin sheet ([approximately] 1.5 mm) of light at various locations in the axial/radial and radial/azimuthal planes. By varying the time delay between introduction of the seeding material and data acquisition, features of the flow that would ordinarily be inaccessible are revealed. Laser Doppler velocimetry is used to measure the time-averaged and root mean square velocity components in all three coordinate directions. Using these data, a model is contructed of the flow from the viewpoint of the vorticity fed into the flow and its subsequent dynamics. This viewpoint suggests different reasons for the development of the observable features of the flow and shows promise for helping to deconvolve the apparent complexity of this flowfield. 13 refs., 13 figs., 2 tabs.

Edwards, C.F.; Fornaciari, N.R.; Dunsky, C.M.; Marx, K.D.; Ashurst, W.T. (Sandia National Laboratories, Livermore, CA (USA). Combustion Research Facility)

1993-08-01

232

Impaired retinal circulation in patients with type 2 diabetes mellitus: retinal laser Doppler velocimetry study.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate the differences in retinal circulation in eyes of patients with type 2 diabetes with no or early-stage diabetic retinopathy compared with control eyes. METHODS: Seventy-five nondiabetic eyes and 194 eyes with type 2 diabetes mellitus were evaluated. The type 2 diabetic eyes were classified into two groups: 139 eyes (139 patients) without diabetic retinopathy (NDR) and 55 eyes (55 patients) with mild nonproliferative diabetic retinopathy (NPDR). The retinal circulatory parameters were measured with laser Doppler velocimetry, and the factors that affect retinal hemodynamics were determined in a cross-sectional population of patients with type 2 diabetes. RESULTS: The group-averaged blood velocity (V) and retinal blood flow (RBF) in the NDR and mild NPDR groups were significantly (P < 0.01) lower than in the non-DM group. The diameter and wall shear rate were also significantly (P < 0.05) lower in the NDR group than in the nondiabetic control eyes. Multiple regression analysis showed that the RBF was independently and negatively correlated with serum low-density lipoprotein and creatinine. HbA1c was significantly (P < 0.05) higher in participants in the lowest RBF quartile than in the highest quartiles. CONCLUSIONS: The results indicate that the RBF may decrease in patients with type 2 diabetes without retinopathy and in those with mild retinopathy.

Nagaoka T; Sato E; Takahashi A; Yokota H; Sogawa K; Yoshida A

2010-12-01

233

Estimation of scattering phase function utilizing laser Doppler power density spectra.  

UK PubMed Central (United Kingdom)

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.

Wojtkiewicz S; Liebert A; Rix H; Sawosz P; Maniewski R

2013-02-01

234

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.

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

2013-01-01

235

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

Science.gov (United States)

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

Thompson, Michael W.; Atchley, Anthony A.

2005-04-01

236

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

UK PubMed Central (United Kingdom)

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.

He D; Nguyen HC; Hayes-Gill BR; Zhu Y; Crowe JA; Gill C; Clough GF; Morgan SP

2013-01-01

237

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

Scientific Electronic Library Online (English)

Full Text Available 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 measurements 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 (more) 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.

Pinotti, Marcos; Faria, Edna M. de

2006-09-01

238

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 measurements 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.

Pinotti Marcos; Faria Edna M. de

2006-01-01

239

Comparison between laser speckle contrast imaging and laser Doppler imaging to assess skin blood flow in humans.  

UK PubMed Central (United Kingdom)

OBJECTIVE: We tested the linearity between skin blood flux recorded with laser speckle contrast imaging (LSCI) and laser Doppler imaging (LDI), comparing different ways of expressing data. A secondary objective was to test within-subject variability of baseline flux with the two techniques. METHODS: We performed local heating at 36, 39, 42, and 44°C on the forearm of healthy volunteers, and measured cutaneous blood flux with LDI and LSCI. Biological zero (BZ) was obtained by occluding the brachial artery. We expressed data as raw arbitrary perfusion units (APUs) and as a percentage increase from baseline (%BL), with and without subtracting BZ. Inter-site variability was expressed as a within subject coefficient of variation (CV). RESULTS: Twelve participants were enrolled. Inter-site variability at baseline was lower with LSCI (CV=9.2%) than with LDI (CV=20.7%). We observed an excellent correlation between both techniques when data were expressed as raw APUs or APU-BZ (R=0.90; p<0.001). The correlation remained correct for %BL (R=0.77, p<0.001), but decreased for %BL-BZ (R=0.44, p=0.003). Bland-Altman plots revealed a major proportional bias between the two techniques. CONCLUSION: This study suggests that skin blood flux measured with LSCI is linearly related to the LDI signal over a wide range of perfusion. Subtracting BZ does not affect this linearity but introduces variability in baseline flux, thus decreasing the correlation when data are expressed as a function of baseline. Finally, systematic bias makes it impossible to assimilate arbitrary perfusion units provided by the two systems.

Millet C; Roustit M; Blaise S; Cracowski JL

2011-09-01

240

Flowmeter tubes and method of installing them  

UK PubMed Central (United Kingdom)

A method of preventing the inserting of a wrong flowmeter tube into an anesthesia machine comprises the steps of forming a selected number of longitudinal ridges at selected places on the inside surface of an upper portion of a flowmeter tube, attempting to insert the upper end portion into a socket pin mounted on the housing of a anesthesia machine, seating the tube on the socket pin if the socket pin exterior surface has grooves corresponding to the number and placement of ridges on the flowmeter tube, and rejecting the tube by the socket pin if the socket pin exterior surface does not have grooves corresponding to the number and placement of the ridges on the flowmeter tube, since the lack of said correspondences indicates that the tube is the wrong tube for the socket pin. A flowmeter measuring tube for medical applications such as anesthesia machines has a selected number of ridges extending inwardly from the inside surface of the flowmeter tube from an upper end portion, said number of ridges being adapted to slide into a like number and position of grooves in a socket pin of a housing of an anesthesia machine for holding the tube in place, whereby the ridges of the flowmeter tube and the grooves of the socket pin provide a safety feature that prevents the insertion of the wrong tube into the socket pin.

Porter Gary K.

 
 
 
 
241

Analysis of molecular dynamics of colloidal particles in transported dilute samples by self-mixing laser Doppler velocimetry.  

UK PubMed Central (United Kingdom)

Colloidal particles in a liquid medium are transported with constant velocity, and dynamic light scattering experiments are performed on the samples by self-mixing laser Doppler velocimetry. The power spectrum of the modulated wave induced by the motion of the colloidal particles cannot be described by the well-known formula for flowing Brownian motion systems, i.e., a combination of Doppler shift, diffusion, and translation. Rather, the power spectrum was found to be described by the q-Gaussian distribution function. The molecular mechanism resulting in this anomalous line shape of the power spectrum is attributed to the anomalous molecular dynamics of colloidal particles in transported dilute samples, which satisfy a nonlinear Langevin equation.

Sudo S; Ohtomo T; Iwamatsu M; Osada T; Otsuka K

2012-01-01

242

Laser-Doppler-measurements of power-density-spectra in a turbulent channel flow  

International Nuclear Information System (INIS)

[en] In this paper the results of measurements in a turbulent channel flow are presented. A Laser-Doppler-Anemometer is used. The fluid is water. The velocity component in the direction of the main flow and one component perpendicular to it are recorded. Both the Reynolds-number and the distance to the wall are varied. Particularly, the power-density-spectra of the velocity fluctuations are evaluated. These spectra are investigated in details distinguishing three different wavenumber ranges. The range of lower wavenumbers, respectively frequencies are presented by an approximation equation, and an empirical length-scale appearing in that equation is determined. A subrange having an -1-exponent is also investigated. The theoretically predicted shape of the spectrum in the intermediate wavenumber range is verified by the measurements. The two wavenumbers representing the lower respectively the upper limit of that range are determined as a function of Reynolds-number. In the upper range, the spectra are contaminated by a significant amount of noise which is shown to be a consequence of the measurement-method itself. The reasons and possible method to eliminate the noise are discussed. The spectral variation of the energy ratio for the different velocity directions and the existence of isotropy were considered. The results are spectra in a Reynolds-number range where the validity of the common 'universal' relations cannot be generally assumed. The deductions can be used to support models which are employed for the numerical simulation of turbulent flows and which require the knowledge of power-density-spectra. (orig.)[de] In dieser Arbeit werden die Ergebnisse von Messungen in einer turbulenten Kanalstroemung erlaeutert. Als Messmethode wird die Laser-Doppler-Anemometrie verwendet; das Fluid ist Wasser. Gemessen wird sowohl die Hauptstroemungskomponente der Geschwindigkeit, als auch eine Komponente senkrecht dazu. Parameter sind die Reynoldszahl und der Wandabstand. Ausgewertet werden insbesondere die Energiedichtespektren der Geschwindigkeitsschwankungen. Diese Spektren werden in der vorliegenden Arbeit im Detail betrachtet. Die Spektren werden dazu in drei Bereiche unterteilt. Der Bereich niedriger Frequenzen bzw. Wellenzahlen wird mit einer Naeherungsgleichung dargestellt und der darin enthaltene Parameter berechnet. Der in diesem Bereich vorhandene -1-Verlauf wird ebenfalls ausgewertet. Im Bereich mittlerer Wellenzahlen wird der theoretisch vorhergesagte Verlauf durch die Messungen bestaetigt, und es werden die beiden Grenzwerte dieses Bereiches als Funktion der Reynoldszahl dargestellt. Im Bereich hoher Wellenzahlen kommt es zu einer starken Ueberlagerung des Nutzsignals durch Stoerungen, die sich groesstenteils auf inhaerente Eigenschaften der verwendeten Messmethode zuruckfuehren lassen. Auf die Ursachen und moegliche Massnahmen zur Behebung dieses Mangels wird eingegangen. Des weiteren werden die Energieverhaeltnisse in den Spektren und die Frage der Existenz von Isotropie behandelt. Die Ergebnisse liefern Energiedichtespektren in turbulenten Stroemungen in Reynoldszahlbereichen, wo die ueblichen 'universellen' Beziehungen nicht mehr angenommen werden duerfen. Die Auswertungen koennen zur Unterstuetzung von Rechenmodellen, die die turbulente Stroemung numerisch simulieren, herangezogen werden. Diese Modelle setzen die Kenntnis der Energiedichtespektren voraus. (orig.)

1977-01-01

243

Autonomous structural health monitoring technique for interplanetary drilling applications using laser Doppler velocimeters  

Science.gov (United States)

The research work presented in this thesis is devoted to the formulation and field testing of a dynamics-based structural health monitoring system for an interplanetary subsurface exploration drill system. Structural health monitoring is the process of detecting damage or other types of defects in structural and mechanical systems that have the potential to adversely affect the current or future performance of these systems. Interplanetary exploration missions, specifically to Mars, involve operations to search for water and other signs of extant or past life. Such missions require advanced robotic systems that are more susceptible to structural and mechanical failures, which motivates a need for structural health monitoring techniques relevant to interplanetary exploration systems. Strict design requirements for interplanetary exploration missions create unique research problems and challenges compared with structural health monitoring procedures and techniques developed to date. These challenges include implementing sensors and devices that will not interfere with the drilling operation, producing "real-time" diagnostics of the drilling condition, and developing an automation procedure for complete autonomous operations. The first research area involves modal analysis experiments to understand the dynamic characteristics of interplanetary drill structural systems in operation. These experiments also validate the use of Laser Doppler Velocimeter sensors in real-time structural health monitoring and prove the drill motor system adequately excites the drill for dynamic measurements and modal analysis while the drill is in operation. The second research area involves the development of modal analysis procedures for rotating structures using a Chebyshev signal filter to remove harmonic component and other noise from the rotating drill signal. This filter is necessary to accurately analyze the condition of the rotating drill auger tube while in operation. The third research area involves the development of structural dynamic models to represent the drill system under nominal and expected drilling fault conditions. These models are compared with the modal analysis experimental results and provide theoretical means to analyze the drilling operation and predict fault conditions. The fourth research area involves the formulation of a complete autonomous system to collect and perform the dynamic analysis of the drill signal, identify fault-diagnostic results, and relay these results to the drill Executive computer. The formulated system includes the signal filter, trained Neural Networks, and an automation procedure. Trained Neural Networks are implemented to provide a rapid-response method of relating and comparing the current drill signal with the fault-based structural dynamic models developed in this thesis. Lastly, an automation procedure, and the corresponding software, is developed to interface the measurement equipment, signal filter, Neural Networks, and drill Executive computer to provide a complete hands-off operation of the structural health monitoring system. The fifth research area involves field testing and validation of the developed structural health monitoring system through three field campaigns. Two of these field campaigns were completed at a Mars-analog site in the Canadian Arctic. The automated dynamics-based structural health monitoring technique developed in this thesis presents advanced research accomplishments leading to real-time, autonomous structural health monitoring, and it has been successfully demonstrated on an operating dynamic system. Other major contributions of this thesis work include the formulation and demonstration of real-time, autonomous structural health monitoring in rotating structures using Laser Doppler Velocimeter sensors.

Statham, Shannon M.

244

[Study of cutaneous microcirculation using the laser-Doppler method in syndrome X].  

Science.gov (United States)

Aim of the study was to verify the relationship between syndrome X and generalized microangiopathy. Three groups of patients were selected: Group A, 11 patients with typical syndrome X; Group B, 8 patients with atypical chest pain; Group C, 12 control normal subjects. Microvascular circulation was investigated with a laser Doppler Periflux PF3 at rest (15 min); during ischemia (3 min); during post-ischemic hyperemia on the plantar side of the big toe (where arterovenous anastomoses are particularly abundant) and on the dorsum of the foot (where these anastomoses are very scanty). During each recording we calculated: the mean flux value (FV); the mean concentration of moving blood cells (CMBC); the FV/CMBC ratio (which is related to the flow velocity); the mean percent increase of the three parameters during hyperemia. Patients with syndrome X as compared to the other subjects showed: 1) a significantly higher FV/CMBC ratio at rest and during hyperemia both on the plantar side of the big toe (respectively p = 0.01 and 0.015) and on the dorsum of the foot (respectively p = 0.011 and 0.006). These findings suggest a higher flow velocity in microvascular circulation; significantly lower percent increase of FV and CMBC during hyperemia in the plantar side of the big toe (respectively p = 0.04 and 0.014) but not on the dorsum. The increase of flow velocity at rest and low vasodilatatory reserve after ischemia in an area which is rich of arterovenous anastomoses in patients with syndrome X might be explained by the presence of a basal arterovenous hyperstomia. PMID:8039198

Pignocchino, P; Conte, M R; Scarnato, S; Grande, A

1994-03-01

245

[Study of cutaneous microcirculation using the laser-Doppler method in syndrome X  

UK PubMed Central (United Kingdom)

Aim of the study was to verify the relationship between syndrome X and generalized microangiopathy. Three groups of patients were selected: Group A, 11 patients with typical syndrome X; Group B, 8 patients with atypical chest pain; Group C, 12 control normal subjects. Microvascular circulation was investigated with a laser Doppler Periflux PF3 at rest (15 min); during ischemia (3 min); during post-ischemic hyperemia on the plantar side of the big toe (where arterovenous anastomoses are particularly abundant) and on the dorsum of the foot (where these anastomoses are very scanty). During each recording we calculated: the mean flux value (FV); the mean concentration of moving blood cells (CMBC); the FV/CMBC ratio (which is related to the flow velocity); the mean percent increase of the three parameters during hyperemia. Patients with syndrome X as compared to the other subjects showed: 1) a significantly higher FV/CMBC ratio at rest and during hyperemia both on the plantar side of the big toe (respectively p = 0.01 and 0.015) and on the dorsum of the foot (respectively p = 0.011 and 0.006). These findings suggest a higher flow velocity in microvascular circulation; significantly lower percent increase of FV and CMBC during hyperemia in the plantar side of the big toe (respectively p = 0.04 and 0.014) but not on the dorsum. The increase of flow velocity at rest and low vasodilatatory reserve after ischemia in an area which is rich of arterovenous anastomoses in patients with syndrome X might be explained by the presence of a basal arterovenous hyperstomia.

Pignocchino P; Conte MR; Scarnato S; Grande A

1994-03-01

246

Multiscale entropy of laser Doppler flowmetry signals in healthy human subjects.  

UK PubMed Central (United Kingdom)

PURPOSE: The cardiovascular system (CVS) regulation can be studied from a central viewpoint, through heart rate variability (HRV) data, and from a peripheral viewpoint, through laser Doppler flowmetry (LDF) signals. Both the central and peripheral CVSs are regulated by several interacting mechanisms, each having its own temporal scale. The central CVS has been the subject of many multiscale studies. By contrast, these studies at the level of the peripheral CVS are very recent. Among the multiscale studies performed on the central CVS data, multiscale entropy has been proven to give interesting physiological information for diagnostic purposes. However, no multiscale entropy analysis has been performed on LDF signals. The authors' goal is therefore to propose a first multiscale entropy study of LDF data recorded in healthy subjects. METHODS: The LDF signals recorded in the forearm of seven healthy subjects are processed. Their period sampling is T=50 ms, and coarse-graining scales from T to 23T are studied. Also, for validation, the algorithm is first tested on synthetic signals of known theoretical multiscale entropy. RESULTS: The results reveal nonmonotonic evolution of the multiscale entropy of LDF signals, with a maximum at small scales around 7T and a minimum at longer scales around 18T, singling out in this way two distinctive scales where the LDF signals undergo specific changes from high to low complexity. This also marks a strong contrast with the HRV signals that usually display a monotonic increase in the evolution of the multiscale entropy. CONCLUSIONS: Multiscale entropy of LDF signals in healthy subjects shows variation with scales. Moreover, as the variation pattern observed appears similar for all the tested signals, multiscale entropy could potentially be a useful stationary signature for LDF signals, which otherwise are probe-position and subject dependent. Further work could now be conducted to evaluate possible diagnostic purposes of the multiscale entropy of LDF signals.

Humeau A; Buard B; Mahé G; Rousseau D; Chapeau-Blondeau F; Abraham P

2010-12-01

247

Experimental investigation of a vertical planar jet by ultrasound and laser Doppler velocimetry  

International Nuclear Information System (INIS)

[en] An experimental investigation on the velocity field of a water-jet injected vertically into a water pool was conducted. The jet flowed from a thin rectangular nozzle and was considered to be quasi-planar as it was confined along two parallel planes. Velocity measurements of the jet and the surrounding entrained flow regions were made respectively by ultrasound and laser Doppler velocimetries (UDV and LDV). In contrast to LDV, UDV operates on the principle of pulsed ultrasound echography and in our experiment, a single transducer held at a 10deg angle with respect to horizontal (x-axis) was vertically traversed. The measured velocity thus represents the velocity component along this beam angle. The hydraulic diameter (D) based Reynolds numbers of flow were, Re=1.79 x 104 (UDV), 3.58 x 104 (LDV), 7.15 x 104 (LDV), corresponding to average exit velocities of 0.5, 1.0 and 2.0 m/s. Comparisons of the traditional jet parameters, such as the decay of the centerline and jet's half-radius vs. axial distance (z-axis), against established data confirmed proper jet-like behavior of our test facility. The conclusions from the experiments were as follows: (1) that UDV shows trends and magnitudes similar to data obtained by LDV; both velocimetry methods are applicable to this type of experimental flow configuration, (2) data presented as the axial decay of centerline velocity and jet half-radius, are consistent and similar to past experimental data, mostly of gas jets, and (3) radial profiles show agreement with a past correlation up to R/R1/2=1. There are differences however, between the correlation and the data, for R/R1/2?1, the latter which were showed consistent trends. (author)

1999-01-01

248

Digital laser doppler flowmetry may discriminate "limited" from "diffuse" systemic sclerosis.  

UK PubMed Central (United Kingdom)

OBJECTIVES: To investigate skin blood flux and microvascular functional changes by laser Doppler flowmetry (LD) in patients with systemic sclerosis (SSc) at baseline and following dynamic stimulations. METHODS: Skin blood flux of the dorsal hands was recorded by LD at baseline and after the cold test and the post-occlusive hyperemia test in 59 SSc patients (49 limited cutaneous, 10 diffuse cutaneous). Twenty-five patients with primary Raynaud's phenomenon (PRP), and 31 healthy donors (HD) were studied as controls. RESULTS: After the cold test, SSc patients had a significantly higher reduction of the blood flux (-38.4%+/-28) than PRP (-21.1%+/-37) and HD (-22.1%+/-23) subjects (p<0.05). Within the SSc group, the cold test flux was significantly reduced in limited-SSc (-399%+/-28, p<0.05), but not in diffuse-SSc (-31.2%+/-29), whereas, the time needed to recover the basal flux after the occlusive/ischemic test was significantly longer in diffuse-SSc (18.8s+/-21)than in limited-SSc (4.5s+/-4, p<0.01) or HD (2.2s+/-2, p<0.01) or PRP (0.4s+/-0.7, p<0.01). CONCLUSIONS: These data clearly indicate an impairment of vascular tone regulatory mechanisms in SSc and suggest that a peculiar pathogenic mechanism may be involved in different SSc subset. Nevertheless, it has clear that PRP and SSc-associated RP have a distinct pattern at LD evaluation, and monitoring patients with PRP could be helpful to understand whether a change in the LD pattern might predict the development of SSc.

Grattagliano V; Iannone F; Praino E; De Zio A; Riccardi MT; Carrozzo N; Covelli M; Maggi P; Lapadula G

2010-09-01

249

Completely detection of disturbed and undisturbed flow conditions in pipes with Laser Doppler Velocimetry; Vollflaechige Erfassung von ungestoerten und gestoerten Geschwindigkeitsverteilungen in Rohrleitungen mittels der Laser-Doppler-Velocimetrie  

Energy Technology Data Exchange (ETDEWEB)

Velocity distributions of pipe flows acquired in cross sections by Laser Doppler Velocimetry (LDV) are presented. The mostly automated measuring system consists of a so called ''window chamber'' allowing an extensive optical access with minimum flow disturbance and a three-dimensional iterative beam calculation. Primary and secondary flow structures are presented for disturbed and undisturbed flow conditions. The measurements are part of investigations for the optimization of volume flow calibration test facilities. The minimization of the influence of installation effects on flow meters is as well part of the project. (orig.)

Mueller, U. [OPTOLUTION GmbH, Reinach (Switzerland); Dues, M. [Intelligent Laser Applications GmbH, Juelich (Germany); Baumann, H. [Schweizer Bundesamt fuer Metrologie (METAS), Bern-Wabern (Switzerland)

2007-07-01

250

Repeatability of the evaluation of systemic microvascular endothelial function using laser doppler perfusion monitoring: clinical and statistical implications  

Directory of Open Access Journals (Sweden)

Full Text Available OBJECTIVE: An awareness of the repeatability of biological measures is required to properly design and calculate sample sizes for longitudinal interventional studies. We investigated the day-to-day repeatability of measures of systemic microvascular reactivity using laser Doppler perfusion monitoring. METHODS: We performed laser Doppler perfusion monitoring in combination with skin iontophoresis using acetylcholine and sodium nitroprusside as well as post-occlusive reactive and thermal hyperemia twice within two weeks. The repeatability was assessed by calculating the within-subject standard deviations, limits of agreement, typical errors and intra-class correlation coefficients between days 1 and 2. The ratio of the within-subject standard deviation to the mean values obtained on days 1 and 2 (within-subject standard deviation/GM) was used to determine the condition with the best repeatability. RESULTS: Twenty-four healthy subjects, aged 24.6 + 3.8 years, were recruited. The area under the curve of the vasodilatory response to post-occlusive reactivity showed marked variability (within-subject standard deviation/GM = 0.83), while the area under the curve for acetylcholine exhibited less variability (within-subject standard deviation/ GM = 0.52) and was comparable to the responses to sodium nitroprusside and thermal treatment (within-subject standard deviations/GM of 0.67 and 0.56, respectively). The area under the blood flow/time curve for vasodilation during acetylcholine administration required the smallest sample sizes, the area under the blood flow/time curve during post-occlusive reactivity required the largest sample sizes, and the area under the blood flow/time curves of vasodilation induced by sodium nitroprusside and thermal treatment required intermediate sizes. CONCLUSIONS: In view of the importance of random error related to the day-to-day repeatability of laser Doppler perfusion monitoring, we propose an original and robust statistical methodology for use in designing prospective clinical studies.

Eduardo Tibiriçá; Alessandra SM Matheus; Bruno Nunes; Sandro Sperandei; Marilia B. Gomes

2011-01-01

251

Human skin microcirculation after brachial plexus block evaluated by wavelet transform of the laser Doppler flowmetry signal.  

UK PubMed Central (United Kingdom)

BACKGROUND: The skin microcirculation may be evaluated noninvasively by laser Doppler flowmetry and iontophoresis with acetylcholine and sodium nitroprusside. Wavelet transform of the perfusion signal shows periodic oscillations of five characteristic frequencies in the interval 0.0095-1.6 Hz. The aim of the current study was to investigate alterations in skin microcirculation induced by brachial plexus block, with emphasis on the periodic oscillations. METHODS: Healthy nonsmokers undergoing hand surgery (n = 13) were anesthetized with brachial plexus block, using bupivacaine, lidocaine, and epinephrine. Skin microcirculation was evaluated by laser Doppler flowmetry and iontophoresis with acetylcholine and sodium nitroprusside before and after brachial plexus block. Wavelet transform of the perfusion signal was performed. As a control group, 10 healthy nonsmokers were included. RESULTS: In the anesthetized arm, skin perfusion after brachial plexus block increased from 19 (12-30) to 24 (14-39) arbitrary units (P < 0.01). A significant increase was also seen in the contralateral arm from 17 (14-32) to 20 (14-42) arbitrary units (P < 0.01). After brachial plexus block, spectral analysis revealed a significant reduction in relative amplitude of the oscillatory components within the 0.0095- to 0.021- (P < 0.001) and 0.021- to 0.052-Hz (P < 0.001) intervals in the anesthetized arm. CONCLUSION: Alterations in skin microcirculation induced by brachial plexus block can be evaluated by wavelet transform of the laser Doppler flowmetry signal. Brachial plexus block reduces the oscillatory components within the 0.0095- to 0.021- and 0.021- to 0.052-Hz intervals of the perfusion signal. These alterations are related to inhibition of sympathetic activity and a possible impairment of endothelial function.

Landsverk SA; Kvandal P; Kjelstrup T; Benko U; Bernjak A; Stefanovska A; Kvernmo H; Kirkeboen KA

2006-09-01

252

Highly spatially resolving laser Doppler velocity measurements of the tip clearance flow inside a hard disk drive model  

Science.gov (United States)

The flow in the tip clearance of a hard disk drive model has been investigated with laser Doppler techniques. The flow was driven by co-rotating disks inside a cylindrical enclosure in order to simulate a hard disk drive used for data storage devices. The main focus of the investigation was on the understanding of complex flow behavior in the narrow gap region between the disk tip and the outer shroud wall, which is supposed to be one of the causes of flow induced vibration of the disks. Experiments in the past have never been able to examine this region because of the lack of the spatial resolution of sensors in the highly three-dimensional flow in the region. In the present investigation, the flow velocity in the tip clearance region was measured with optical measurement techniques for the first time. The flow behaviors are investigated for four different conditions with two different gap widths and two different shapes of the shroud walls with and without ribs. The velocity measurements were taken both with conventional laser Doppler velocimetry and using a laser Doppler velocity profile sensor with a spatial resolution in the micrometer range. The circumferential velocity component was measured along the axial and radial directions. The steep gradients of the circumferential mean velocity in both directions were successfully captured with a high spatial resolution, which was achieved by the velocity profile sensor. From the supplementary investigations, the existence of vortex structures in the tip clearance region was confirmed with a dependence on the shroud gap width and the shroud shape. The interactions of the two boundary layers seem to be the source of the complex three-dimensional behaviors of the flow in this region.

Shirai, Katsuaki; Yaguchi, Yusuke; Büttner, Lars; Czarske, Jürgen; Obi, Shinnosuke

2011-03-01

253

Repeatability of the evaluation of systemic microvascular endothelial function using laser doppler perfusion monitoring: clinical and statistical implications  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english OBJECTIVE: An awareness of the repeatability of biological measures is required to properly design and calculate sample sizes for longitudinal interventional studies. We investigated the day-to-day repeatability of measures of systemic microvascular reactivity using laser Doppler perfusion monitoring. METHODS: We performed laser Doppler perfusion monitoring in combination with skin iontophoresis using acetylcholine and sodium nitroprusside as well as post-occlusive reacti (more) ve and thermal hyperemia twice within two weeks. The repeatability was assessed by calculating the within-subject standard deviations, limits of agreement, typical errors and intra-class correlation coefficients between days 1 and 2. The ratio of the within-subject standard deviation to the mean values obtained on days 1 and 2 (within-subject standard deviation/GM) was used to determine the condition with the best repeatability. RESULTS: Twenty-four healthy subjects, aged 24.6 + 3.8 years, were recruited. The area under the curve of the vasodilatory response to post-occlusive reactivity showed marked variability (within-subject standard deviation/GM = 0.83), while the area under the curve for acetylcholine exhibited less variability (within-subject standard deviation/ GM = 0.52) and was comparable to the responses to sodium nitroprusside and thermal treatment (within-subject standard deviations/GM of 0.67 and 0.56, respectively). The area under the blood flow/time curve for vasodilation during acetylcholine administration required the smallest sample sizes, the area under the blood flow/time curve during post-occlusive reactivity required the largest sample sizes, and the area under the blood flow/time curves of vasodilation induced by sodium nitroprusside and thermal treatment required intermediate sizes. CONCLUSIONS: In view of the importance of random error related to the day-to-day repeatability of laser Doppler perfusion monitoring, we propose an original and robust statistical methodology for use in designing prospective clinical studies.

Tibiriçá, Eduardo; Matheus, Alessandra SM; Nunes, Bruno; Sperandei, Sandro; Gomes, Marilia B.

2011-01-01

254

100-mW linear polarization single-frequency all-fiber seed laser for coherent Doppler lidar application  

Science.gov (United States)

A compact short-cavity fiber laser configured with Er 3+ /Yb 3+ highly co-doped phosphate glass fiber with stable linear polarization and single frequency output is proposed and investigated experimentally. The fiber laser is composed of a high-reflectivity fiber Bragg grating (HRFBG) and a polarization-maintaining fiber Bragg grating (PMFBG) with the matched wavelengths at 1540.3 nm, which aims at one of the center wavelengths of the atmospheric transmission windows and may be used as the local oscillator (LO) of the coherent Doppler lidar (CDL). The output power of the laser reaches more than 114-mW, the signal-to-noise ratio is larger than 70 dB and the laser linewidth is about 4.1-kHz. Moreover, the linear polarization with 40.5 dB extinction ratio, the power fluctuation of less than ± 0.25% and the frequency fluctuation of less than ± 80 MHz are also obtained. Compared with the DFB fiber laser, the proposed fiber laser is more suitable for the CDL applications.

Yang, Fei; Ye, Qing; Pan, Zhengqing; Chen, Dijun; Cai, Haiwen; Qu, Ronghui; Yang, Zhongmin; Zhang, Qinyuan

2012-01-01

255

Flowmeter for pressure-driven chromatography systems  

Energy Technology Data Exchange (ETDEWEB)

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

256

Flowmeter for pressure-driven chromatography systems  

Energy Technology Data Exchange (ETDEWEB)

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)

2002-01-01

257

Development of the immersed sodium flowmeter  

International Nuclear Information System (INIS)

[en] An immersed sodium flowmeter of the range 3 m3/h is developed. It is a flowmeter of entire-sealed construction, it can be operated in sodium. Its construction, the theoretical calculation of the calibration characteristic and the pressure loss, the test facility and the calibration test are presented in detail. It analytical expression of the calibration characteristic in the temperature limit 200?600 degree C and the error analysis are given. The basic error of this immersed sodium flowmeter is below +-2.3% of the measuring range. The immersed sodium flowmeter can be used to resolve the sodium flowrate measuring problems of the in-reactor component of LMFBR, for example, the flowrate measuring of the in-reactor sodium purification loop, the flowrate measuring of the immersed sodium pump and the flowrate measuring of the in-reactor test component

1994-01-01

258

Effect of a stack on Rayleigh streaming cells investigated by laser Doppler velocimetry for application to thermoacoustic devices (L).  

UK PubMed Central (United Kingdom)

A preliminary study was conducted to observe the influence of a stack on the Rayleigh streaming pattern for application to thermoacoustic devices. The velocity field was estimated from laser Doppler velocimetry measurements in a resonator first without a stack; then a stack was placed at various positions along the resonator axis for various acoustic levels. It was observed that adding a stack locally modifies the streaming pattern and that new streaming vortices appear. When the stack position approaches the location of the streaming velocity maximum or when the acoustic velocity amplitude is increased, the amplitude of additional acoustic streaming vortices at the ends of the stack increases.

Moreau S; Bailliet H; Valière JC

2009-06-01

259

Effect of a stack on Rayleigh streaming cells investigated by laser Doppler velocimetry for application to thermoacoustic devices (L).  

Science.gov (United States)

A preliminary study was conducted to observe the influence of a stack on the Rayleigh streaming pattern for application to thermoacoustic devices. The velocity field was estimated from laser Doppler velocimetry measurements in a resonator first without a stack; then a stack was placed at various positions along the resonator axis for various acoustic levels. It was observed that adding a stack locally modifies the streaming pattern and that new streaming vortices appear. When the stack position approaches the location of the streaming velocity maximum or when the acoustic velocity amplitude is increased, the amplitude of additional acoustic streaming vortices at the ends of the stack increases. PMID:19507931

Moreau, Solenn; Bailliet, Hélène; Valière, Jean-Christophe

2009-06-01

260

An investigation of a sonic flowmeter  

Energy Technology Data Exchange (ETDEWEB)

A new sonic flowmeter has been tested at various air velocities from 0.25 m/s up to 20 m/s. The air velocities measured by the flowmeter were compared with the velocities measured using a pitot-static tube. The velocity readings obtained by the flowmeter were less than the velocity measured by the pitot-static tube. This was due to the fact that the velocity inside the flowmeter is less than the velocity outside. This, however, can be compensated for by including calibrating points in the program used for evaluation. The effects of variations of the distance between the transducers and the diameter of the tube in which the transducers are located were also investigated. The output values of the velocities measured increase exponentially for low wind velocities and small tube diameters, and linearly for higher wind velocities. Increased tube diameter gave higher measured velocities, due to increased air speed inside the tube, and also gave more linear velocity curves at low air velocities. The flowmeter seems to be insensitive to misalignement angles of less than 10{degree} and, with only a small decrease in output values, to angles between 10{degree} and 25{degree}. This investigation shows that the new sonic flowmeter can be a useful tool in the measurement of air velocities. 8 figs., 2 refs.

Olsen, E. (Chalmers Univ. of Tech., Goeteborg (Sweden)); Strindehag, O. (Flaekt AB, Joenkoeping (Sweden))

1991-04-01

 
 
 
 
261

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

Science.gov (United States)

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

Thompson, Michael W.

262

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

UK PubMed Central (United Kingdom)

OBJECTIVE: 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). METHODS: This was a prospective, randomized, blinded diagnostic accuracy study. Toe and ankle pressures were measured using both methods in 200 consecutive patients, who were recruited at our vascular laboratory over a period of 30 working days. Classification of PAD and critical limb ischemia (CLI) was made in accordance with TASC-II criteria. RESULTS: The LDF method demonstrated 5.8 mm Hg higher mean toe pressures than the SGP method for the right limb and 7.0 mm Hg for the left limb (both P < .001). There were no significant differences in the mean ankle pressures (both P > .129). The limits of agreement for the differences (SGP - LDF) were -31.7 to 20.2 mm Hg for right toe pressures, -28.0 to 14.0 mm Hg for left toe pressures, -25.5 to 22.8 mm Hg for right ankle pressures, and -26.9 to 24.6 mm Hg for left ankle pressures. A correlation analysis of the absolute pressures using the two methods showed an intraclass correlation coefficient of 0.902 (95% confidence interval [CI], 0.835-0.938) for right toe pressures, 0.919 (95% CI, 0.782-0.960) for the left toe pressures, 0.953 (95% CI, 0.937-0.965) for right ankle pressures, and 0.952 (95% CI, 0.936-0.964) for left ankle pressures. Cohen's Kappa showed an agreement in the diagnostic classification of ? = 0.775 (95% CI, 0.631-0.919) for PAD and ? = 0.780 (95% CI, 0.624-0.936) for CLI. CONCLUSIONS: LDF showed a good correlation with SGP over a wide range of toe and ankle pressures, as well as substantial agreement for the diagnostic classification of PAD including CLI.

Høyer C; Sandermann J; Paludan JP; Pavar S; Petersen LJ

2013-07-01

263

Laser Doppler vibrometer: unique use of DOE/Taguchi methodologies in the arena of pyroshock (10 to 100,000 HZ) response spectrum  

Science.gov (United States)

Discussed is the unique application of design of experiment (DOE) to structure and test a Taguchi L9 (32) factorial experimental matrix (nine tests to study two factors, each factor at three levels), utilizing an HeNe laser Doppler vibrometer and piezocrystal accelerometers to monitor the explosively induced vibrations through the frequency range of 10 to 105 Hz on a flat steel plate (96 X 48 X 0.25 in.). An initial discussion is presented of pyrotechnic shock, or pyroshock, which is a short-duration, high-amplitude, high-frequency transient structural response in aerospace vehicle structures following firing of an ordnance item to separate, sever missile skin, or release a structural member. The development of the shock response spectra (SRS) is detailed. The use of a laser doppler for generating velocity- acceleration-time histories near and at a separation distance from the explosive and the resulting generated shock response spectra plots is detailed together with the laser doppler vibrometer setup as used. The use of DOE/Taguchi as a means of generating performance metrics, prediction equations, and response surface plots is presented as a means to statistically compare and rate the performance of the NeHe laser Doppler vibrometer with respect to two different piezoelectric crystal accelerometers of the contact type mounted directly to the test plate at the frequencies in the 300, 3000, and 10,000 Hz range. Specific constructive conclusions and recommendations are presented on the totally new dimension of understanding the pyroshock phenomenon with respect to the effects and interrelationships of explosive charge weight, location, and the laser Doppler recording system. The use of these valuable statistical tools on other experiments can be cost-effective and provide valuable insight to aid understanding of testing or process control by the engineering community. The superiority of the HeNe laser Doppler vibrometer performance is demonstrated.

Litz, C. J.

1994-09-01

264

Detailed study of the Fourier transform of the time-interval photon statistics distribution applied to laser Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

In this paper a technique consisting of measuring the Fourier transform Q/sub F/ of the time-interval photon statistics distribution is studied when applied to laser Doppler velocimetry. It is supposed that a device that changes the Gaussian intensity profile of the laser beam into a uniform intensity profile is used. A theoretical model for a fluid with a constant velocity is obtained and verified by two ways: experimentally and by a computer-simulation method. Then the experimental conditions for which the signal can be approached to a Lorentzian curve and the error involved in the determination of the fluid velocity are studied from the theoretical model. It is concluded that the measurement of Q/sub F/ is a useful technique for very low intensities.

Rebolledo, M.A.; Alvarez, J.M.; Amare, J.C.

1988-09-15

265

Longitudinal studies on the microcirculation around the TheraCyte immunoisolation device, using the laser Doppler technique.  

UK PubMed Central (United Kingdom)

Encapsulation of cellular grafts in an immunoisolation membrane device may make it possible to perform transplantation without having to give immunosuppressive drugs. A common problem is the development of an avascular fibrotic zone around the implants, leading to impaired graft survival. The TheraCyte macroencapsulation device has therefore been designed to facilitate neovascularization of the device's surface. In this study, we evaluated the microcirculation around empty TheraCyte devices implanted SC in rats at various times after implantation, using a laser Doppler probe introduced via the device port. Studies were performed on day 1 or at 1, 2, and 4 weeks or at 2, 3, and 12 months after implantation. The mean flow was 158+/-42, 148+/-50, 133+/-28, 72+/-17, 138+/-41, 165+/-43, and 160+/-29 perfusion units (PU), respectively. Thus, the microcirculation around the device was significantly reduced at 4 weeks after implantation (p < 0.01) while, from 2 months onwards the circulation had improved and did not differ significantly from that on day 1. The present study shows time-related changes in the microcirculatory flow around TheraCyte macroencapsulation devices that agree with our previous microdialysis studies on in vivo exchange of insulin and glucose between the device and the circulation. Laser Doppler flowmetry seems to provide a reliable technique for screening blood perfusion around macroencapsulation devices.

Rafael E; Gazelius B; Wu GS; Tibell A

2000-01-01

266

Evaluation of late radiation-induced changes of the superficial microcirculation. I. clinical benefit of the cutaneous Doppler laser  

International Nuclear Information System (INIS)

Objective. - The changes that occur in the tissular microcirculation after therapeutic irradiation (RT) account for some of the late effects of irradiation, especially on the cutaneous level. As a rule, the methods of exploring the superficial microcirculation only measure blood flow indirectly. Only the Doppler laser can provide direct measurements of blood parameters in vivo in man. Methods. -Thirty women who had been irradiated with 45 + 20 Gy of locoregional fractionated adjuvant RT for breast cancer developed local radiation-induced fibrosis six years later (±5). The local microcirculation was measured in the resting state and during thermal stimulation at 42 deg. C, using a Periflux cutaneous Doppler laser with p413 probes. Three periods of six minutes each were continuously recorded: period 1 (P1) represented basal resting cutaneous perfusion, with the slope p corresponding to the increase in perfusion when two minutes of thermal stimulation at 42 deg. C began; P2 to plateau perfusion during this stimulation; and P3 to perfusion on the return to equilibrium. Each individual was its own control. Results. - In the women treated by RT, the resting microcirculation in the skin underlying an area of late fibrosis rose by a factor of 2 during P1 (p

2000-01-01

267

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.

2011-02-01

268

A Near Infrared Laser Frequency Comb for High Precision Doppler Planet Surveys  

CERN Document Server

We discuss the laser frequency comb as a near infrared 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.

Osterman, S; Quinlan, F; Bally, J; Ge, J; Ycas, G

2010-01-01

269

The study of the flow in an helico-axial pump using laser doppler velocimetry; Exploration par anemometrie laser doppler de l'ecoulement dans une pompe helico-axiale  

Energy Technology Data Exchange (ETDEWEB)

The increasing interest in the development of multiphase flow pumping and the performances in cavitating regime characterising inducers, partially incited the Institut Francais du Petrole (IFP) to develop rotors of the same type as the one equipping the pump of the actual study with a configuration similar to that of inducers. This paper presents the work led within the framework of the experimental study of multiphase flow in turbomachinery. We present the results obtained by Laser Doppler velocimetry in the rotor of an helico-axial pump. Before starting the study in a multiphase environment, it was interesting, at first, to understand the nature of the flow with a single phase fluid. The measurements synchronized with the angular position of the rotor, allowed to restore the relative flow and thus to access to a better understanding of the flow structure in the inducers. (authors)

El Hajem, M.; Morel, R.; Champagne, J.Y. [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France)

2001-07-01

270

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.

Baker Rose D; Weinand Christian; Jeng James C; Hoeksema Henk; Monstrey Stan; Pape Sarah A; Spence Robert; Wilson David

2009-01-01

271

Trace isotope analysis using resonance ionization mass spectrometry based on isotope selection with doppler shift of laser ablated atoms  

International Nuclear Information System (INIS)

[en] We have proposed a novel isotope selective Resonance Ionization Mass Spectroscopy (RIMS) concept, which can avoid the Doppler broadening on solid sample direct measurement based on laser ablation technique. We have succeeded in experimentally demonstrating the principle of our RIMS concept. Through comparison between the simulated and experimental results, we have validated the simulation model. It would be concluded from these results that we could achieve the isotope selectivity defined as the ratio of 41Ca to 40Ca sensitivity to be 4.5x1010 by adopting the multi-step excitation scheme in the present method. As future works, we will try to experimentally perform the multi-step excitation scheme and improve the detection efficiency by modifying the ion extraction configuration. (author)

2005-01-01

272

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

UK PubMed Central (United Kingdom)

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

Bharadvaj BK; Mabon RF; Giddens DP

1982-01-01

273

A measurement on the turbulent flow of variable cross sectioned 180 deg. bend by using laser doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

The subject of internal flow in a very broad and complex one, encompassing a wide variety of geometries and flow situations there are many examples of machinery in which internal flows play an important part. one such example is the modern turbofan engine here the understanding of internal flow is very important in predicting the performance of many key components. There include the inlets and exhaust nozzles at the extremities of the engine, the rotating and stationary turbomachinery blade rows in both the compressor and turbing sections of the engine. In this study the characteristics of the three dimensional turbulence flow in the variable cross sectioned bends were investigated by experimental method. In the experimental study, two velocity and Reynolds stress component are measured by LDV (Laser Doppler Velocimetry) (author). 5 refs., 11 figs., 2 tabs.

Seo, J.S. [Graduate School, Korea University, Seoul (Korea); Kim, W.K. [Post Doctoral, Seoul National University, Seoul (Korea); Choi, Y.D. [Korea University, Seoul (Korea)

1999-04-01

274

Application of laser Doppler velocimetry. Proceedings of the Osaka symposium on flow measuring-techniques, Osaka, Japan  

Energy Technology Data Exchange (ETDEWEB)

Consideration is given to a number of applications of laser Doppler velocimetry (LDV) in the field of flow measurement, including LDV anemometers for turbulence measurements in open channel flows; velocity measurements in rod bundles; and LDV measurement of the pipe flow of a dilute drag-reducing polymer solution. Among the other topics discussed are: LDV measurements of a turbulent free convection boundary layer along a vertical surface; LDV measurement of gas flow velocities in spark ignition engines; flow measurement by photoelectron correlation; and the calculation of signal visibility in LDV particle size measurements. Consideration is also given to: a prototype LDV with optical fiber pickups; measurements of flow velocity distribution and space correlation with an LDV light-receiving system; and LDV analysis of the structure of blood flows through blood vessels.

1984-01-01

275

Photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid  

International Nuclear Information System (INIS)

[en] The authors present an optically based method combining photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid. The frequency spectrum of a silicon cantilever measured in water over frequencies ranging up to 10 MHz shows that the method allows us to excite and detect higher modes, from fundamental to fifth flexural, without enhancing spurious resonances. By reducing the tip oscillation amplitude using higher modes, the average tip-sample force gradient due to chemical bonds is effectively increased to achieve high-spatial-resolution imaging in liquid. The method's performance is demonstrated by atomic resolution imaging of a mica surface in water obtained using the second flexural mode with a small tip amplitude of 99 pm; individual atoms on the surface with small height differences of up to 60 pm are clearly resolved.

2008-01-01

276

Electro-kinetics of charged-sphere suspensions explored by integral low-angle super-heterodyne laser Doppler velocimetry  

International Nuclear Information System (INIS)

[en] We investigated the flow behaviour of colloidal charged-sphere suspensions using a newly designed integral low-angle super-heterodyne laser Doppler velocimetry instrument, which combines the advantages of several previous approaches. Sample conditions ranged from strong electrostatic interactions with pronounced short-range order to individual particles with no spatial correlations. The obtained power spectra correspond to diffusion broadened velocity distributions across the complete sample cross section. The excellent performance of the instrument is highlighted in detail by the example of electro-kinetic flow of suspensions in a closed cell of a rectangular cross section. We demonstrate the excellent performance of our approach with the example of electro-phoretic-electro-osmotic experiments, showing that a comprehensive flow characterization becomes possible by analysing the measured electro-kinetic mobilities, the flow-profile, an effective diffusion coefficient and the integrated scattering density. We briefly discuss present limitations, possible extensions and interesting applications in other fields.

2012-11-21

277

Electro-kinetics of charged-sphere suspensions explored by integral low-angle super-heterodyne laser Doppler velocimetry  

Science.gov (United States)

We investigated the flow behaviour of colloidal charged-sphere suspensions using a newly designed integral low-angle super-heterodyne laser Doppler velocimetry instrument, which combines the advantages of several previous approaches. Sample conditions ranged from strong electrostatic interactions with pronounced short-range order to individual particles with no spatial correlations. The obtained power spectra correspond to diffusion broadened velocity distributions across the complete sample cross section. The excellent performance of the instrument is highlighted in detail by the example of electro-kinetic flow of suspensions in a closed cell of a rectangular cross section. We demonstrate the excellent performance of our approach with the example of electro-phoretic-electro-osmotic experiments, showing that a comprehensive flow characterization becomes possible by analysing the measured electro-kinetic mobilities, the flow-profile, an effective diffusion coefficient and the integrated scattering density. We briefly discuss present limitations, possible extensions and interesting applications in other fields.

Palberg, Thomas; Köller, Tetyana; Sieber, Bastian; Schweinfurth, Holger; Reiber, Holger; Nägele, Gerhard

2012-11-01

278

Photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid.  

Science.gov (United States)

The authors present an optically based method combining photothermal excitation and laser Doppler velocimetry of higher cantilever vibration modes for dynamic atomic force microscopy in liquid. The frequency spectrum of a silicon cantilever measured in water over frequencies ranging up to 10 MHz shows that the method allows us to excite and detect higher modes, from fundamental to fifth flexural, without enhancing spurious resonances. By reducing the tip oscillation amplitude using higher modes, the average tip-sample force gradient due to chemical bonds is effectively increased to achieve high-spatial-resolution imaging in liquid. The method's performance is demonstrated by atomic resolution imaging of a mica surface in water obtained using the second flexural mode with a small tip amplitude of 99 pm; individual atoms on the surface with small height differences of up to 60 pm are clearly resolved. PMID:19123565

Nishida, Shuhei; Kobayashi, Dai; Sakurada, Takeo; Nakazawa, Tomonori; Hoshi, Yasuo; Kawakatsu, Hideki

2008-12-01

279

Using dynamic analysis of Laser-Doppler blood flowmetry to measure nasal mucosa bloody flow in postural changes.  

UK PubMed Central (United Kingdom)

BACKGROUND: The regulation of nasal mucosa blood flow (NMBF) is affected by multiple factors, such as the autonomic nervous system, medications, temperature, humidity, endocrine, even emotional stress and vision. The effects of postural changes on NMBF have been described in numerous studies. However, the results are far from consistent due to different experimental designs. OBJECTIVE: Dynamic analysis of Laser-Doppler blood flowmetry (LDBF) is employed to recognize the effect of postural changes on NMBF. METHODS: NMBF was continuously measured by LDBF in 14 participants with changing postures (sitting and supine). NMBF was measured in Blood Perfusion Unit (BPU), equivalent to the number of red blood cells multiplied by their mean velocity in a measured volume. RESULTS: NMBF increases significantly in a supine posture compared with that in a sitting posture. CONCLUSION: Our study demonstrates that NMBF is significantly influenced after initial postural change, suggesting that changes in posture may be regarded as an important factor regulating NMBF.

Tsai KK; Yen CF; Chu YH; Wang HW

2012-12-01

280

Development and Application of an Ultrasonic Gas Flowmeter  

Energy Technology Data Exchange (ETDEWEB)

This paper describes the development and the field application of the ultrasonic gas flowmeter for accurate measurement of the volumetric flow rate of gases in a harsh environmental conditions in iron and steel making company. This ultrasonic flowmeter is especially suited for measuring LDG, COG, BFG gases produced in iron and steel making process. This is a transit time type ultrasonic flowmeter. We have developed the transmitting and receiving algorithm of ultrasonic wave and the ultrasonic signal processing algorithm to develope a transit time type ultrasonic flowmeter. We have evaluated the performance of ultrasonic flowmeter by the calibration system with Venturi type standard flowmeter. We has confirmed its reliability by extensive field tests for a year in POSCO, iron and steel making company. Now we have developed the commercial model of ultrasonic flowmeter and applied to the POSCO gas line

Hwang, Won Ho; Jeong, Hee Don [Research Institute of Industrial Science and Technology, Pohang (Korea, Republic of); Park, Sang Gug [Uiduk University, Gyeongju (Korea, Republic of); Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of)

2002-06-15

 
 
 
 
281

Development and Application of an Ultrasonic Gas Flowmeter  

International Nuclear Information System (INIS)

[en] This paper describes the development and the field application of the ultrasonic gas flowmeter for accurate measurement of the volumetric flow rate of gases in a harsh environmental conditions in iron and steel making company. This ultrasonic flowmeter is especially suited for measuring LDG, COG, BFG gases produced in iron and steel making process. This is a transit time type ultrasonic flowmeter. We have developed the transmitting and receiving algorithm of ultrasonic wave and the ultrasonic signal processing algorithm to develope a transit time type ultrasonic flowmeter. We have evaluated the performance of ultrasonic flowmeter by the calibration system with Venturi type standard flowmeter. We has confirmed its reliability by extensive field tests for a year in POSCO, iron and steel making company. Now we have developed the commercial model of ultrasonic flowmeter and applied to the POSCO gas line

2002-01-01

282

Assessment of the effects of low-level laser therapy on the thyroid vascularization of patients with autoimmune hypothyroidism by color Doppler ultrasound.  

UK PubMed Central (United Kingdom)

Background. Chronic autoimmune thyroiditis (CAT) frequently alters thyroid vascularization, likely as a result of the autoimmune process. Objective. To evaluate the effects of low-level laser therapy (LLLT) on the thyroid vascularization of patients with hypothyroidism induced by CAT using color Doppler ultrasound parameters. Methods. In this randomized clinical trial, 43 patients who underwent levothyroxine replacement for CAT-induced hypothyroidism were randomly assigned to receive either 10 sessions of LLLT (L group, n = 23) or 10 sessions of a placebo treatment (P group, n = 20). Color Doppler ultrasounds were performed before and 30 days after interventions. To verify the vascularity of the thyroid parenchyma, power Doppler was performed. The systolic peak velocity (SPV) and resistance index (RI) in the superior (STA) and inferior thyroid arteries (ITAs) were measured by pulsed Doppler. Results. The frequency of normal vascularization of the thyroid lobes observed in the postintervention power Doppler examination was significantly higher in the L than in the P group (P = 0.023). The pulsed Doppler examination revealed an increase in the SPV of the ITA in the L group compared with the P group (P = 0.016). No significant differences in the SPV of the STA and in the RI were found between the groups. Conclusion. These results suggest that LLLT can ameliorate thyroid parenchyma vascularization and increase the SPV of the ITA of patients with hypothyroidism caused by CAT.

Höfling DB; Chavantes MC; Juliano AG; Cerri GG; Knobel M; Yoshimura EM; Chammas MC

2012-01-01

283

Sub-Doppler spectroscopy with an external cavity quantum cascade laser  

Science.gov (United States)

The linewidth of an external cavity quantum cascade laser is studied as a function of injection current and laser scan rate. The laser linewidth is inferred to be ca. 2.5 MHz from Lamb-dip spectra on a low pressure sample of NO and its variation with injection current is well modeled using literature values for the intrinsic material properties of the lasing medium. The laser linewidth measurements are corroborated by polarization spectroscopy studies as well as by analysis of hyperfine structure and cross-over resonances.

Walker, R. J.; Kirkbride, J.; van Helden, J. H.; Weidmann, D.; Ritchie, G. A. D.

2013-08-01

284

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

285

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

286

The "Swiss-cheese Doppler-guided laser tonsillectomy": a new safe cribriform approach to intracapsular tonsillectomy.  

UK PubMed Central (United Kingdom)

Outpatient laser ablation of palatine tonsils is a very interesting procedure that has been recently introduced as a routine in head and neck surgery departments. The aim of this study was to describe a new strategy using a Doppler-guided fibre optic neodymium-yttrium-aluminium-garnet (YAG) laser to remove up to 80 % of tonsillar tissue, as assessed in the long-term postoperative clinical evaluation of the volume of the tonsils at the follow-up, and leaving the capsule in place, thus avoiding any haemorrhagic complication and minimize pain. A total of 20 patients (men, n=13; women, n=7), aged between 6 and 63, were recruited for the procedure. They were affected by chronic hypertrophic tonsillitis with a recurrent fever and other symptoms that were related to oral inflammation. Among the 20 patients, no serious adverse events, including haemorrhage-related complications, were observed. Treatment was well tolerated, even in patients displaying an overall low pain threshold. No dropout or uncompleted procedure occurred in the present study. Minor complications included sore throat, moderate oedema, mild acute pharynx inflammation, slight peritonsillar exudate and local burning. The postoperative pain, measured by Scott-Huskisson visual analogue scale, was between 5 and 40 mm and was easily counteracted by means of external ice packages and nonsteroidal anti-inflammatory drugs, according to the individual patient's need. During the 12-36-month follow-up patients showed improved symptoms (n=7) and complete recovery (n=13). A relapse episode was observed in two patients. This study supports fibre optic laser neodymium-YAG tonsil surgery, named "cribriform intracapsular tonsillectomy" or "Swiss-cheese laser tonsillectomy", as an effective alternative to the traditional cold knife approach or electrosurgery. This approach could become the gold standard for tonsil surgery in the third millennium for safety reasons, acceptable cost-benefit ratio, the precise targeting of the beam across the affected tissues and the short- and long-term recovery.

Palmieri B; Iannitti T; Fistetto G; Rottigni V

2013-05-01

287

Development of permanent-magnet sodium flowmeter  

International Nuclear Information System (INIS)

[en] Two permanent-magnet sodium flowmeters of rangs 5 m3/h and 0.5 m3/h are developed. Their constructions, the theoretical calculations of calibration characteristic and pressure loss, the calibration test and the error analysis are presented. The analytical expressions of the calibration characteristic are given

1991-01-01

288

BOREHOLE FLOWMETERS: FIELD APPLICATION AND DATA ANALYSIS  

Science.gov (United States)

This paper reviews application of borehole flowmeters in granular and fractured rocks. asic data obtained in the field are the ambient flow log and the pumping-induced flow log. hese basic logs may then be used to calculate other quantities of interest. he paper describes the app...

289

A New Approach to Laminar Flowmeters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

After studying the performance and characteristics of actual laminar flowmeters a new disposition for this type of sensors is proposed in such a way that the measurement errors introduced by the intrinsic nature of the device can be minimized. The preliminary study shows that the developing entry re...

Fernando Lopez Pena; Alvaro Deibe; Marcos Rodriguez; Santiago Vazquez

290

Study on corona discharge air mass flowmeter  

Energy Technology Data Exchange (ETDEWEB)

In order to measure the instantaneous flow rate of intake air of engines, a corona discharge air mass flowmeter equipped with a detector with tripple coaxial cylinders was manufactured by way of trial, and an experiment was conducted. A corona discharge function of the flow rate detector and a flow rate detecting function were separated in the composition. By this, the followings are superior to conventional corona discharge flowmeter: Since the flow rate detector has a complete double coaxial cylinders structure, output of the flowmeter possesses equal sensitivities to both directions of downflow and back flow, and this flowmeter has linearity and no hysteresis is observed. Inconvenience due to dust adhesion is hardly yielded because a discharge electrode is not bared in the air flow. While, general characteristics are confirmed as follows: Instantaneous air flow can be measured due to excellent dynamic response. Measuring pulsating air flow such as the intake air is also possible due to directivity to the flow. By integrating the instantaneous air flow, cyclic mean flow can be measured. 12 refs., 13 figs.

Tanaka, Munenobu; Kitajima, Unpei; Fujibayashi, Koichi; Doi, Saburo; Sato, Tadanori (Tokai Univ., School of Engineering, Tokyo, Japan Tokyo Univ. of Agriculture and Tech., Faculty of Tech., Tokyo (Japan) Fuji Heavy Industries Ltd., Tokyo (Japan))

1989-08-25

291

Differential doppler heterodyning technique  

DEFF Research Database (Denmark)

Measuring velocity without disturbing the moving object is possible by use of the laser doppler heterodyning technique. Theoretical considerations on the doppler shift show that the antenna property of the photodetector can solve an apparent conflict between two different ways of calculating the detected doppler frequency. It is found that the doppler frequency for this particular setup is independent of the direction of detection. Investigations of the signal-to-noise ratio (SNR) show that the maximum SNR-considering the optical setup-is obtained by measuring the frequency difference between two doppler-shifted beams rather than by measuring the shift of a single beam by comparing it with a reference beam. Measurements seem to be in agreement with the theoretical consideration

Lading, Lars

1971-01-01

292

1.5-?m high-average power laser amplifier using a Er,Yb:glass planar waveguide for coherent Doppler lidar  

Science.gov (United States)

We have developed a 1.5-?m eye-safe wavelength high average power laser amplifier using an Er,Yb:glass planar waveguide for coherent Doppler LIDAR. Large cooling surface of the planar waveguide enabled high average power pumping for Er,Yb:glass which has low thermal fracture limit. Nonlinear effects are suppressed by the large beam size which is designed by the waveguide thickness and the beam width of the planar direction. Multi-bounce optical path configuration and high-intensity pumping provide high-gain and high-efficient operation using three-level laser material. With pulsed operation, the maximum pulse energy of 1.9 mJ was achieved at the repetition rate of 4 kHz. Output average power of the amplified signal was 7.6W with the amplified gain of more than 20dB. This amplifier is suitable for coherent Doppler LIDAR to enhance the measurable range.

Sakimura, Takeshi; Watanabe, Yojiro; Ando, Toshiyuki; Kameyama, Shumpei; Asaka, Kimio; Tanaka, Hisamichi; Yanagisawa, Takayuki; Hirano, Yoshihito; Inokuchi, Hamaki

2012-11-01

293

Laser Doppler imaging of cutaneous blood flow through transparent face masks: a necessary preamble to computer-controlled rapid prototyping fabrication with submillimeter precision.  

UK PubMed Central (United Kingdom)

A paradigm shift in management of postburn facial scarring is lurking "just beneath the waves" with the widespread availability of two recent technologies: precise three-dimensional scanning/digitizing of complex surfaces and computer-controlled rapid prototyping three-dimensional "printers". Laser Doppler imaging may be the sensible method to track the scar hyperemia that should form the basis of assessing progress and directing incremental changes in the digitized topographical face mask "prescription". The purpose of this study was to establish feasibility of detecting perfusion through transparent face masks using the Laser Doppler Imaging scanner. Laser Doppler images of perfusion were obtained at multiple facial regions on five uninjured staff members. Images were obtained without a mask, followed by images with a loose fitting mask with and without a silicone liner, and then with a tight fitting mask with and without a silicone liner. Right and left oblique images, in addition to the frontal images, were used to overcome unobtainable measurements at the extremes of face mask curvature. General linear model, mixed model, and t tests were used for data analysis. Three hundred seventy-five measurements were used for analysis, with a mean perfusion unit of 299 and pixel validity of 97%. The effect of face mask pressure with and without the silicone liner was readily quantified with significant changes in mean cutaneous blood flow (P < .5). High valid pixel rate laser Doppler imager flow data can be obtained through transparent face masks. Perfusion decreases with the application of pressure and with silicone. Every participant measured differently in perfusion units; however, consistent perfusion patterns in the face were observed.

Allely RR; Van-Buendia LB; Jeng JC; White P; Wu J; Niszczak J; Jordan MH

2008-01-01

294

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

295

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

296

A comparative study of colour and perfusion between two different post surgical scars. Do the laser Doppler imager and the colorimeter measure the same features of a scar?  

UK PubMed Central (United Kingdom)

BACKGROUND/PURPOSE: The purpose of this study was to investigate the influence of different located post surgical scars on both perfusion and redness. The pattern of change and correlation between perfusion and redness of post surgical scars is also examined. METHODS: In this study, we measured redness and perfusion of the abdominal and breast scar of 24 women undergoing breast reconstruction with Deep Inferior Epigastric Perforator Free Flap surgery with the Minolta Chromameter CR-400/410 and the Moor Instruments laser Doppler imager 12IR, respectively, at different intervals post-operatively. RESULTS: The laser Doppler imager gives significantly higher values for the abdominal compared with the breast scar. There was no consistent correlation found between perfusion and redness at the different test moments for both locations. The scores of both parameters were significantly associated after 9 months follow-up for both locations. CONCLUSION: Scars closed with higher mechanical force show higher perfusion and prolonged activity; and more redness is associated with more perfusion for both post surgical scars. Nevertheless, there was no consistent correlation found between these parameters making the laser Doppler imager and the Colorimeter still non-replaceable instruments.

Mermans JF; Peeters WJ; Dikmans R; Serroyen J; van der Hulst RR; Van den Kerckhove E

2013-05-01

297

Gas measurement using Coriolis mass flowmeters  

Energy Technology Data Exchange (ETDEWEB)

This paper demonstrates Coriolis mass flowmeters (CMF) can provide a solution for measuring the mass flowrate of gases directly, i.e. no knowledge of the gas properties is required. The test results for natural gas and compressed air presented here were obtained using a standard factory water calibration. This demonstrates properly designed CMF and linear devices and can provide accurate results independent of gas composition over wide pressure and mass flowrate ranges.

Pawlas, G.; Patten, T. [Micro Motion, Inc., Boulder, CO (United States)

1995-12-31

298

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.

Osterman S.; Diddams S.; Quinlan F.; Bally J.; Ge J.; Ycas G.

2011-01-01

299

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.

Adelaide Greco; Monica Ragucci; Raffaele Liuzzi; Sara Gargiulo; Matteo Gramanzini; Anna Rita Daniela Coda; Sandra Albanese; Marcello Mancini; Marco Salvatore; Arturo Brunetti

2012-01-01

300

Multifractal analysis of heart rate variability and laser Doppler flowmetry fluctuations:comparison of results from different numerical methods  

International Nuclear Information System (INIS)

To contribute to the understanding of the complex dynamics in the cardiovascular system (CVS), the central CVS has previously been analyzed through multifractal analyses of heart rate variability (HRV) signals that were shown to bring useful contributions. Similar approaches for the peripheral CVS through the analysis of laser Doppler flowmetry (LDF) signals are comparatively very recent. In this direction, we propose here a study of the peripheral CVS through a multifractal analysis of LDF fluctuations, together with a comparison of the results with those obtained on HRV fluctuations simultaneously recorded. To perform these investigations concerning the biophysics of the CVS, first we have to address the problem of selecting a suitable methodology for multifractal analysis, allowing us to extract meaningful interpretations on biophysical signals. For this purpose, we test four existing methodologies of multifractal analysis. We also present a comparison of their applicability and interpretability when implemented on both simulated multifractal signals of reference and on experimental signals from the CVS. One essential outcome of the study is that the multifractal properties observed from both the LDF fluctuations (peripheral CVS) and the HRV fluctuations (central CVS) appear very close and similar over the studied range of scales relevant to physiology.

2010-10-21

 
 
 
 
301

Early detection of microcirculatory perfusion changes with a high resolution, real time laser Doppler imaging camera--frostbite case study.  

Science.gov (United States)

A 41-year-old male presented with severe frostbite that was monitored clinically and with a new laser Doppler imaging (LDI) camera that records arbitrary microcirculatory perfusion units (1-256 arbitrary perfusion units (APU's)). LDI monitoring detected perfusion differences in hand and foot not seen visually. On day 4-5 after injury, LDI showed that while fingers did not experience any significant perfusion change (average of 31±25 APUs on day 5), the patient's left big toe did (from 17±29 APUs day 4 to 103±55 APUs day 5). These changes in regional perfusion were not detectable by visual examination. On day 53 postinjury, all fingers with reduced perfusion by LDI were amputated, while the toe could be salvaged. This case clearly demonstrates that insufficient microcirculatory perfusion can be identified using LDI in ways which visual examination alone does not permit, allowing prognosis of clinical outcomes. Such information may also be used to develop improved treatment approaches. PMID:22679257

Erba, Paolo; Harbi, Pascal; Thacher, Tyler; Pries, Axel; Ambrosio, Giuseppe; Raffoul, Wassim

2011-09-19

302

Early detection of microcirculatory perfusion changes with a high resolution, real time laser Doppler imaging camera--frostbite case study.  

UK PubMed Central (United Kingdom)

A 41-year-old male presented with severe frostbite that was monitored clinically and with a new laser Doppler imaging (LDI) camera that records arbitrary microcirculatory perfusion units (1-256 arbitrary perfusion units (APU's)). LDI monitoring detected perfusion differences in hand and foot not seen visually. On day 4-5 after injury, LDI showed that while fingers did not experience any significant perfusion change (average of 31±25 APUs on day 5), the patient's left big toe did (from 17±29 APUs day 4 to 103±55 APUs day 5). These changes in regional perfusion were not detectable by visual examination. On day 53 postinjury, all fingers with reduced perfusion by LDI were amputated, while the toe could be salvaged. This case clearly demonstrates that insufficient microcirculatory perfusion can be identified using LDI in ways which visual examination alone does not permit, allowing prognosis of clinical outcomes. Such information may also be used to develop improved treatment approaches.

Erba P; Harbi P; Thacher T; Pries A; Ambrosio G; Raffoul W

2011-01-01

303

Measurements by laser Doppler velocimetry in the casing/impeller clearance gap of a biocentrifugal ventricular assist device model.  

Science.gov (United States)

The velocity distributions in the clearance gap of the Kyoto-NTN biocentrifugal ventricular assist device model were measured by laser Doppler velocimetry (LDV) at three inlet flow conditions, namely operating, fully opened, and fully closed conditions. The results obtained have a similar trend as in the earlier measurements using air as medium and the hot-wire probe, a washout mechanism that is a segment of fluids in the gap situated from theta = 60 degrees to 220 degrees, has a larger radial velocity component flowing toward the eye of the pump, as compared to other regions in the gap where the tangential velocity component is dominant. It is essential to have a good washout for the leakage flow through the clearance gap between the stationary casing and the impeller of the pump so that the blood will not keep on circulating in the gap but is washed out to the eye in order to reduce the chances of being destroyed. Although the detailed velocity distributions are not the same, this should be due to the minor fabrication differences between two pump models. The current noninvasive LDV measurements should have a better representation of the actual flow field than the earlier studies due to the blood analog being used as the flow medium. Furthermore, as compared to the methods used in the earlier studies, there is basically no modification of the pump geometry in the present measurement. PMID:19335413

Chua, Leok Poh; Ong, Kang Shiu; Song, Guoliang; Ji, Wenfa

2009-04-01

304

Measurements by laser Doppler velocimetry in the casing/impeller clearance gap of a biocentrifugal ventricular assist device model.  

UK PubMed Central (United Kingdom)

The velocity distributions in the clearance gap of the Kyoto-NTN biocentrifugal ventricular assist device model were measured by laser Doppler velocimetry (LDV) at three inlet flow conditions, namely operating, fully opened, and fully closed conditions. The results obtained have a similar trend as in the earlier measurements using air as medium and the hot-wire probe, a washout mechanism that is a segment of fluids in the gap situated from theta = 60 degrees to 220 degrees, has a larger radial velocity component flowing toward the eye of the pump, as compared to other regions in the gap where the tangential velocity component is dominant. It is essential to have a good washout for the leakage flow through the clearance gap between the stationary casing and the impeller of the pump so that the blood will not keep on circulating in the gap but is washed out to the eye in order to reduce the chances of being destroyed. Although the detailed velocity distributions are not the same, this should be due to the minor fabrication differences between two pump models. The current noninvasive LDV measurements should have a better representation of the actual flow field than the earlier studies due to the blood analog being used as the flow medium. Furthermore, as compared to the methods used in the earlier studies, there is basically no modification of the pump geometry in the present measurement.

Chua LP; Ong KS; Song G; Ji W

2009-04-01

305

Hemodynamic changes during neural deactivation in awake mice: A measurement by laser-Doppler flowmetry in crossed cerebellar diaschisis.  

UK PubMed Central (United Kingdom)

Crossed cerebellar diaschisis (CCD) caused by contralateral supratentorial lesions can be considered a condition of neural deactivation, and hemodynamic changes in CCD were investigated with positron emission tomography (PET) in humans. In the present study, to investigate the effects of neural deactivation on hemodynamics, we developed a new mouse model of CCD, which was caused by middle cerebral artery occlusion (MCAO), and measured changes in cerebellar blood flow (CbBF), red blood cell (RBC) velocity and concentration due to CCD using laser-Doppler flowmetry (LDF) in awake mice. The ratio of the CCD side to the unaffected side in the cerebellum for CbBF 1 day after MCAO was decreased by -18% compared to baseline (before CCD). The ratio of the CCD side to the unaffected side for RBC concentration 1 day after MCAO was decreased by -23% compared to baseline. However, no significant changes in the ratio of the CCD side to the unaffected side were observed for RBC velocity. The present results indicate that the reduction of CbBF induced by neural deactivation was mainly caused by the decrease in RBC concentration. In contrast, our previous study showed that RBC velocity had a dominant role in the increase in cerebral blood flow (CBF) induced by neural activation. If RBC concentration can be considered an indicator of cerebral blood volume (CBV), hemodynamic changes due to neural activation and deactivation measured by LDF in mice might be in good agreement with human PET studies.

Takuwa H; Tajima Y; Kokuryo D; Matsuura T; Kawaguchi H; Masamoto K; Taniguchi J; Ikoma Y; Seki C; Aoki I; Tomita Y; Suzuki N; Kanno I; Ito H

2013-09-01

306

Prosthetic reconstruction from the tympanic membrane to the stapes head or to the stapes footplate? A laser Doppler study.  

UK PubMed Central (United Kingdom)

BACKGROUND: In the absence of the incus, many surgeons believe that reconstruction from the tympanic membrane to the stapes head is more effective than reconstruction to the stapes footplate. This has rarely been tested empirically. Published better clinical results with reconstruction to the stapes head might simply reflect less underlying disease in ears with an intact stapes superstructure. OBJECTIVE: To compare vibration transmission of these two forms of prosthetic reconstruction. METHODS: A fresh human cadaveric temporal bone model was used. Round window vibrations in response to sound in the ear canal were measured with a laser Doppler vibrometer. After incus removal, the discontinuity was repaired using a titanium prosthesis. Reconstruction from the tympanic membrane to the stapes head was compared to reconstruction to the stapes footplate. RESULTS: Reconstruction of both types decreased round window vibrations by 10 to 15 dB between 500 and 3000 Hz compared to the intact middle ear. Reconstruction to the stapes head performed 5 to 10 dB better at lower frequencies (500-2000 Hz), but this was only statistically significant at 1 and 2 kHz. CONCLUSIONS: There is only a 5 to 10 dB mechanical advantage gained by reconstruction from the tympanic membrane to the stapes head compared to reconstruction to the footplate for frequencies between 1 and 2 kHz.

Alian WA; Majdalawieh OF; Van Wijhe RG; Ejnell H; Bance M

2012-04-01

307

Repeatability, reproducibility and standardisation of a laser Doppler imaging technique for the evaluation of normal mouse hindlimb perfusion.  

UK PubMed Central (United Kingdom)

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.

Greco A; Ragucci M; Liuzzi R; Gargiulo S; Gramanzini M; Coda AR; Albanese S; Mancini M; Salvatore M; Brunetti A

2013-01-01

308

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

309

The influence of wellbore inflow on electromagnetic borehole flowmeter measurements.  

UK PubMed Central (United Kingdom)

This paper describes a combined field, laboratory, and numerical study of electromagnetic borehole flowmeter measurements acquired without the use of a packer or skirt to block bypass flow around the flowmeter. The most significant finding is that inflow through the wellbore screen changes the ratio of flow through the flowmeter to wellbore flow. Experiments reveal up to a factor of two differences in this ratio for conditions with and without inflow through the wellbore screen. Standard practice is to assume the ratio is constant. A numerical model has been developed to simulate the effect of inflow on the flowmeter. The model is formulated using momentum conservation within the borehole and around the flowmeter. The model is embedded in the MODFLOW-2000 ground water flow code.

Clemo T; Barrash W; Reboulet EC; Johnson TC; Leven C

2009-07-01

310

Extrinsic factors affecting accuracy of ultrasonic flowmeters for LMFBRs  

International Nuclear Information System (INIS)

[en] Assuming that ultrasonic flowmeters of suitable intrinsic accuracy are feasible, this report explores factors extrinsic to the flowmeter which affect the accuracy such as asymmetric flow profile, regions of high turbulence and thermal stratification. By integrating isovelocity flow profile maps, the predicted performance of various flowmeter configurations may be compared to experimental data. For the two pipe arrangements analyzed, the single diametral path flowmeter results were within 5 percent of true flow rate. Theoretical correction factors could reduce the error for the straight pipe but increased the error for asymmetrical flow. On the same pipe arrangements a four path ultrasonic flowmeter spaced for Gaussian integration gave less than 1 percent error. For more general conclusions a range of flow profiles produced by typical LMFBR piping arrangements must be analyzed

1976-01-01

311

Nailfold capillaroscopy and blood flow laser-doppler analysis of the microvascular damage in systemic sclerosis: preliminary results  

Directory of Open Access Journals (Sweden)

Full Text Available Objectives: Systemic sclerosis (SSc) is characterized by altered microvascular structure and function. Nailfold videocapillaroscopy (NVC) is the tool to evaluate capillary morphological structure and laser-Doppler Blood flowmetry (LDF) can be used to estimate cutaneous blood flow of microvessels. The aim of this study was to investigate possible relationships between capillary morphology and blood flow in SSc. Methods: 27 SSc patients and 12 healthy subjects were enrolled. SSc microvascular involvement, as evaluated by NVC, was classified in three different patterns (“Early”, “Active”, “Late”). LDF analysis was performed at the II, III, IV, V hand fingers in both hands and both at cutaneous temperature and at 36°C. Statistical evaluation was carried out by non-parametric procedures. Results: Blood flow was found significantly lower in SSc patients when compared with healthy subjects (p<0.05). The heating of the probe to 36°C induced a significant increase in peripheral blood flow in all subjects compared to baseline (p <0.05), however, the amount of variation was significantly lower in patients with SSc, compared with healthy controls (p <0.05). The SSc patients with NVC “Late” pattern, showed lower values of peripheral blood flow than patients with NVC “Active” or “Early” patterns (p<0.05). Moreover, a negative correlation between the tissue perfusion score and the progression of the SSc microangiopathy was observed, as well as between the tissue perfusion and the duration of the Raynaud’s phenomenon (p <0.03). Conclusions: LDF can be employed to evaluate blood perfusion in the microvascular circulation in SSc patients. The blood flow changes observed with the LDF seem to correlate with the severity of microvascular damage in SSc as detected by NVC.

M.E. Secchi; A. Sulli; C. Pizzorni; M. Cutolo

2011-01-01

312

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 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

1985-01-01

313

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

314

Photonic doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

We are developing a novel fiber-optic approach to laser Doppler velocimetry as a diagnostic for high explosives tests. Using hardware that was originally developed for the telecommunications industry, we are able to measure surface velocities ranging from centimeters per second to kilometers per second. Laboratory measurements and field trials have shown excellent agreement with other diagnostics.

Lowry, M E; Molau, N E; Sargis, P D; Strand, O T; Sweider, D

1999-01-01

315

Photonic doppler velocimetry  

International Nuclear Information System (INIS)

[en] We are developing a novel fiber-optic approach to laser Doppler velocimetry as a diagnostic for high explosives tests. Using hardware that was originally developed for the telecommunications industry, we are able to measure surface velocities ranging from centimeters per second to kilometers per second. Laboratory measurements and field trials have shown excellent agreement with other diagnostics

1999-01-01

316

Doppler-free spectroscopy of the 1S0-3P0 optical clock transition in laser-cooled fermionic isotopes of neutral mercury  

CERN Document Server

We have performed for the first time direct laser spectroscopy of the 1S0-3P0 optical clock transition at 265.6 nm in fermionic isotopes of neutral mercury laser-cooled in a magneto-optical trap. Spectroscopy is performed by measuring the depletion of the magneto-optical trap induced by the excitation of the long-lived 3P0 state by a probe at 265.6 nm. Measurements resolve the Doppler-free recoil doublet allowing for a determination of the transition frequency to an uncer- tainty well below the Doppler-broadened linewidth. We have performed absolute measurement of the frequency with respect to an ultra-stable reference monitored by LNE-SYRTE fountain pri- mary frequency standards using a femtosecond laser frequency comb. The measured frequency is 1128575290808 +/- 5.6 kHz in 199Hg and 1128569561140 +/- 5.3 kHz in 201Hg, more than 4 orders of magnitude better than previous indirect determinations. Owing to a low sensitivity to blackbody radiation, mercury is a promising candidate for reaching the ultimate perf...

Petersen, M; Dawkins, S T; Magalhães, D V; Mandache, C; Lecoq, Y; Clairon, A; Bize, S

2008-01-01

317

The determination of local frequency distribution of particle velocities in disperse two-phase-flow using a laser-doppler-velocimeter (LDV)  

International Nuclear Information System (INIS)

[en] Laser-Doppler velocimetry is a suitable method for measuring the local velocity of individual particles in a disperse gassolid flow. A representative local particle velocity distribution can be obtained for a particle system with a given particle size distribution, provided the particle velocities for all particle size classes are likewise recorded by counting and analyzing single LD-bursts. A 'repressentative'esentative measurement is of special importance in case any correlation exists between particle velocity and particle size. An LDV-system meeting the above specification will be described. Based on the results of extensive experimental work on LD-signal quality for particle sizes between 20 and 300 ?m, the measuring system can be adapted in accordance with various particulate properties. The effects of the adaptation parameters are schematically discussed. Measurements in a vertical gas-solids pipe flow show the usefulness of the suggested method. With the knowledge of the complete local particle velocity distributions an advantage in interpreting special flow phenomena exists. (orig.)[de] Mit Hilfe des Laser-Doppler-Verfahrens kann die lokale Geschwindigkeit einzelner Partikeln in einer Gas-Feststoff-Stroemung gemessen werden. Unter Beruecksichtigung bestimmter Voraussetzungen erhaelt man damit fuer ein Kollektiv mit gegebener Partikelgroessenverteilung die repraesentativen lokalen Haeufigkeitsverteilungen der Partikelgeschwindigkeiten. Die Voraussetzungen betreffen vor allem die Erfassung der Partikelgeschwindigkeiten aller Partikelgroessenklassen im Falle einer Abhaengigkeit zwischen Partikelgroesse und Partikelgeschwindigkeit. Es wird eine Laser-Doppler-Messeinrichtung (LDV) beschrieben, welche den besonderen messtechnischen Anforderungen entspricht. Die Ergebnisse ausfuehrlicher experimenteller Untersuchungen der LD-Signalqualitaet fuer Partikeln im Korngroessenbereich zwischen 20 bis 300 ?m liefern Hinweise fuer die Anpassung des Systems an die jeweils vorliegenden Partikeleigenschaften. Die Auswirkungen verschiedener Anpassungsparameter werden schematisch diskutiert. Die Brauchbarkeit der vorgeschlagenen Messmethode wird anhand von Messungen in einer vertikalen Gas-Feststoff-Rohrstroemung aufgezeigt. Dabei bedeutet die Kenntnis der vollstaendigen oertlichen Partikelgeschwindigkeitsverteilungen einen Vorteil fuer die Interpretation spezieller Stroemungserscheinungen. (orig.)

1979-09-26

318

Measurements of wound edge microvascular blood flow during negative pressure wound therapy using thermodiffusion and transcutaneous and invasive laser Doppler velocimetry.  

Science.gov (United States)

The effects of negative pressure wound therapy (NPWT) on wound edge microvascular blood flow are not clear. The aim of the present study was therefore to further elucidate the effects of NPWT on periwound blood flow in a porcine peripheral wound model using different blood flow measurement techniques. NPWT at -20, -40, -80, and -125?mmHg was applied to a peripheral porcine wound (n?=?8). Thermodiffusion, transcutaneous, and invasive laser Doppler velocimetry were used to measure the blood perfusion 0.5, 1.0, and 2.5?cm from the wound edge. Thermodiffusion (an invasive measurement technique) generally showed a decrease in perfusion close to the wound edge (0.5?cm), and an increase further from the edge (2.5?cm). Invasive laser Doppler velocimetry showed a similar response pattern, with a decrease in blood flow 0.5?cm from the wound edge and an increase further away. However, 1.0?cm from the wound edge blood flow decreased with high pressure levels and increased with low pressure levels. A different response pattern was seen with transcutaneous laser Doppler velocimetry, showing an increase in blood flow regardless of the distance from the wound edge (0.5, 1.0, and 2.5?cm). During NPWT, both increases and decreases in blood flow can be seen in the periwound tissue depending on the distance from the wound edge and the pressure level. The pattern of response depends partly on the measurement technique used. The combination of hypoperfusion and hyperperfusion caused by NPWT may accelerate wound healing. PMID:22092843

Borgquist, Ola; Anesäter, Erik; Hedström, Erik; Lee, Charles K; Ingemansson, Richard; Malmsjö, Malin

2011-10-19

319

Measurements of wound edge microvascular blood flow during negative pressure wound therapy using thermodiffusion and transcutaneous and invasive laser Doppler velocimetry.  

UK PubMed Central (United Kingdom)

The effects of negative pressure wound therapy (NPWT) on wound edge microvascular blood flow are not clear. The aim of the present study was therefore to further elucidate the effects of NPWT on periwound blood flow in a porcine peripheral wound model using different blood flow measurement techniques. NPWT at -20, -40, -80, and -125?mmHg was applied to a peripheral porcine wound (n?=?8). Thermodiffusion, transcutaneous, and invasive laser Doppler velocimetry were used to measure the blood perfusion 0.5, 1.0, and 2.5?cm from the wound edge. Thermodiffusion (an invasive measurement technique) generally showed a decrease in perfusion close to the wound edge (0.5?cm), and an increase further from the edge (2.5?cm). Invasive laser Doppler velocimetry showed a similar response pattern, with a decrease in blood flow 0.5?cm from the wound edge and an increase further away. However, 1.0?cm from the wound edge blood flow decreased with high pressure levels and increased with low pressure levels. A different response pattern was seen with transcutaneous laser Doppler velocimetry, showing an increase in blood flow regardless of the distance from the wound edge (0.5, 1.0, and 2.5?cm). During NPWT, both increases and decreases in blood flow can be seen in the periwound tissue depending on the distance from the wound edge and the pressure level. The pattern of response depends partly on the measurement technique used. The combination of hypoperfusion and hyperperfusion caused by NPWT may accelerate wound healing.

Borgquist O; Anesäter E; Hedström E; Lee CK; Ingemansson R; Malmsjö M

2011-11-01

320

Laser Doppler Velocimetry and other advanced measurement methods to improve the accuracy of district heating meter measurement and calibration. Remote reading and communication with district heating meters  

Energy Technology Data Exchange (ETDEWEB)

The conference was held at the Danish Technological Institute in Aarhus in Denmark on 12 and 13 August 1998. The conference was divided into two parts: a seminar on Laser Doppler Velocimetry and other advanced measurement methods to improve the accuracy of district heating meter measurement and calibration, and a one-day conference on Remote reading and communication with district heating meters. The seminar, was aimed at international specialists working within the field of advanced district heating measurement methods. The seminar was attended by 45 people, and the 6 technical presentations addressed advanced optical and ultrasonic measurement methods

NONE

1998-12-31

 
 
 
 
321

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.)

1982-01-01

322

Investigation of the flow characteristics in the spark initiation region of S. I. engines using hot wire and laser Doppler anemometry  

Energy Technology Data Exchange (ETDEWEB)

Laser Doppler and Hot Wire Anemotmetry techniques have been used to measure the gas flows in an I.C. engine. A single cylinder over head valve engine was used in conjunction with both open and compact combustion chamber configurations to investigate the flow in the vicinity of the spark plug. The HWA signal has been analysed using a semi-empirical model, based on Nusselt/Reynold correlation, such that the output could be corrected for the effects of pressure and temperature above those of the probe calibration state. The HWA model was developed using a recirculating uni-axial flow wind tunnel. (author).

Bennett, M.J.

1989-09-01

323

A New Approach to Laminar Flowmeters  

Directory of Open Access Journals (Sweden)

Full Text Available After studying the performance and characteristics of actual laminar flowmeters a new disposition for this type of sensors is proposed in such a way that the measurement errors introduced by the intrinsic nature of the device can be minimized. The preliminary study shows that the developing entry region introduces non-linearity effects in all these devices. These effects bring about not only errors, but also a change in the slope of the linear calibration respect of the Poiseuille relation. After a subsequent analysis on how these non-linearity errors can be reduced, a new disposition of this type of flowmeters is introduced. This device makes used of flow elements having pressure taps at three locations along its length and connected to three isolated chambers. In this way, the static pressure can be measured at three locations and contributed to by the pressure taps at the level of each chamber. Thus the linearization error is reduced with an additional advantage of producing a reduced pressure drop.

Fernando Lopez Pena; Alvaro Deibe; Marcos Rodriguez; Santiago Vazquez

2010-01-01

324

Three-component laser Doppler velocimetry measurements in the vicinity of mechanical heart valves in a mock-circulatory loop  

Science.gov (United States)

Streakline flow visualization and three-component laser Doppler velocimetry were conducted in a mock-circulatory loop on four mechanical heart valve types in the mitral position. Measurements were conducted in the regurgitant flow region proximal to the valve. Results for the Bjork-Shiley Monostrutsp{TM} valve showed a highly non-uniform flow at valve closure, with very large velocities in the minor orifice region. These velocities were on the order of 15-20 mps and lasted less than one millisecond. Following closure, an interval of sustained regurgitant flow persisted for the duration of systole. Reynolds stresses were calculated from three-dimensional data, and yielded a maximum of 8,100 dyne/cmsp2. Values as high as 80,000 dyne/cmsp2 were calculated during the initial spike, but due to the intermittency of the spike, they are artificially high. Similar measurements were conducted in the minor orifice of the Medtronic-Hall valve, and maximum velocities of about 4 mps were measured during the sustained regurgitant flow. Maximum Reynolds shear stresses were about 7,000 dyne/cmsp2. The velocity spike at closing was noted with this valve also. Two-component measurements around the center hole in the occluder showed a sustained jet with maximum velocities of about 1 mps, and maximum Reynolds shear stresses of about 2,000 dyne/cmsp2. Measurements in the St. Jude Medical valve showed velocities and stresses to be very low. No closing spike was measured, and sustained velocities were observed in the hinge region of about 0.2 mps with maximum stresses of about 1,000 dyne/cmsp2. The CarboMedicssp{TM} valve showed a regurgitant jets emanating from the gap between the leaflet and valve housing ring, with velocities of 3.3 mps for the duration of systole, and calculated stresses of 8,100 dyne/cmsp2. No closing spike was noted. Differences between two and three-dimensional Reynolds shear stresses were significant only at locations where two-dimensional calculated values were small (a few hundred dyne/cmsp2). The effect of gap width on maximum shear stress for the Bjork-Shiley Monostrutsp{TM} valve produced inconclusive results. Comparison of stresses with clinical blood damage data showed the Medtronic-Hall and CarboMedicssp{TM} valves to correlate well; however, comparisons with clinical data for the other two valves were inconclusive.

Meyer, Richard Scott

325

Ultrasonic Doppler blood flow meter for extracorporeal circulation  

Science.gov (United States)

In cardiac surgeries it is frequently necessary to carry out interventions in internal heart structures, and where the blood circulation and oxygenation are made by artificial ways, out of the patient's body, in a procedure known as extracorporeal circulation (EC). During this procedure, one of the most important parameters, and that demands constant monitoring, is the blood flow. In this work, an ultrasonic pulsed Doppler blood flowmeter, to be used in an extracorporeal circulation system, was developed. It was used a 2 MHz ultrasonic transducer, measuring flows from 0 to 5 liters/min, coupled externally to the EC arterial line destined to adults perfusion (diameter of 9.53 mm). The experimental results using the developed flowmeter indicated a maximum deviation of 3.5% of full scale, while the blood flow estimator based in the rotation speed of the peristaltic pump presented deviations greater than 20% of full scale. This ultrasonic flowmeter supplies the results in a continuous and trustworthy way, and it does not present the limitations found in those flowmeters based in other transduction methods. Moreover, due to the fact of not being in contact with the blood, it is not disposable and it does not need sterilization, reducing operational costs and facilitating its use.

Dantas, Ricardo G.; Costa, Eduardo T.; Maia, Joaquim M.; Nantes Button, Vera Lucia S.

2000-04-01

326

Coronary stents cause high velocity fluctuation with a flow acceleration and flow reduction in jailed branches: an in vitro study using laser-Doppler anemometry.  

UK PubMed Central (United Kingdom)

Flow disturbance and reduced blood flow have been associated with higher restenosis rates and clinical adverse events after coronary interventions. In the present study, we sought to investigate flow alterations that occurred after stent implantation in a coronary model, within and adjacent to the stented segment. Two stents (Carbostent, Tetrastent) with different strut design were deployed in the left anterior descending artery (LAD) of a 1:1 scaled silicon coronary model. The model was mounted into an artificial circulation and showed distensibility and rheologic behavior comparable to human coronaries. Flow profiles were assessed using laser-Doppler anemometry. Both stents induced a transitional flow within the stents, in the jailed branch as well as in the adjacent segments. However, the alterations in flow were less marked using the Carbostent having stents with thinner struts and a larger strut cell area, and thus seem to be more favorable in avoiding bifurcation lesions. This study shows precisely that stent implantation induces flow disturbances in segments known to be prone for restenosis. Investigations using laser-Doppler measurements may enlighten rheologic phenomena inducing restenosis and help in optimizing stent design and deployment techniques.

Dörler J; Frick M; Hilber M; Breitfuss H; Abdel-Hadi MN; Pachinger O; Liepsch D; Schwarzacher SP

2012-01-01

327

Evaluation of late radiation-induced changes of the superficial microcirculation after acute ?-irradiation. II. prognostic importance of the cutaneous doppler laser  

International Nuclear Information System (INIS)

Objective. -The changes that occur in the tissular microcirculation after accidental acute irradiation account for some of the early effects of such irradiation, especially at the cutaneous level. The prognostic importance of the cutaneous laser doppler was tested in an experimental model of acute ?-irradiation. Methods.-Ten pigs were given ?-irradiation with a high single localized dose of 90Sr/90Y (32 or 64 Gy, 7 mg/cm2) delivered to the flank, and were evaluated 2, 7, 14, 21 and 28 days thereafter. Each individual was its own control. The local microcirculation was measured in the resting state and during thermal stimulation at 42 deg. C, using a Periflux cutaneous Doppler laser with p413 probes. Three periods of six minutes each were continuously recorded: period 1 (P1) represented basal resting cutaneous perfusion, with the slope p corresponding to the increase in perfusion when two minutes of thermal stimulation at 42 deg. C began; P2 to plateau perfusion during this stimulation; and P3 to perfusion on the return to equilibrium. Results. -After acute ?-irradiation in the pig, all the cutaneous microcirculation parameters measured (P1, p, P2 and P3) had risen at day 2 in the irradiated area by a factor of 2 to 4, depending on the dose (p

2000-01-01

328

Doppler Effect  

Science.gov (United States)

In this activity, learners use a tuning fork to explore how the Doppler effect works. They strike the tuning fork to produce a sound, then observe as the tone changes as the fork is swung back and forth. Learners also explore applications of the Doppler effect in technology.

Cosi

2009-01-01

329

Status of the Recent Magnetic Flowmeters  

International Nuclear Information System (INIS)

[en] In order to get the economic benefits and safety of a process facility, 4 major variables - temperature, pressure, level and - should be measured correctly and precisely. The function and performance of recent measuring instruments for the above variables have become sophisticated according to the development of mechanical materials, electronic materials, electronic components such as microprocessors etc. As thermal power of NPP is calculated from the measurement of feedwater temperature and feedwater flowrate, the precise measurement of them could prevent the overpower accident in advance and minimize the power loss. The thermal power margin of US NPP has been guided at 2% by US NRC and NPP electric companies can increase yhe thermal power more than 1% with the use of more advanced instrumentation through the revision of 10 CFR 50 app. k. This report describes general flow measurement technology and the state-of-the art for magnetic flowmeters

2004-01-01

330

Intranasal histamine challenge in normal subjects and allergic rhinitis before and after intranasal budesonide studied with rhinostereometry and micromanipulator-guided laser Doppler flowmetry.  

Science.gov (United States)

Ten healthy subjects and 10 patients suffering from allergic rhinitis to birch pollen were investigated with the combination of rhinostereometry and laser Doppler flowmetry, thus simultaneously measuring changes in mucosal swelling and microcirculation, following intranasal histamine challenge. Compared to normals, the allergies had a higher degree of congestion and a lower increase in perfusion and velocity of flow. In the allergies there was a decrease in CMBC (concentration of moving blood cells) that was not seen in normals. The decrease in CMBC seen in allergies could be attributed to an increase in vascular permeability producing an interstitial edema, a well-known effect of histamine. After treatment with 1 week of intranasal steroid, most of the differences in the reaction pattern between normals and allergies had disappeared. PMID:10654315

Grudemo, H; Juto, J E

331

Intranasal histamine challenge in normal subjects and allergic rhinitis before and after intranasal budesonide studied with rhinostereometry and micromanipulator-guided laser Doppler flowmetry.  

UK PubMed Central (United Kingdom)

Ten healthy subjects and 10 patients suffering from allergic rhinitis to birch pollen were investigated with the combination of rhinostereometry and laser Doppler flowmetry, thus simultaneously measuring changes in mucosal swelling and microcirculation, following intranasal histamine challenge. Compared to normals, the allergies had a higher degree of congestion and a lower increase in perfusion and velocity of flow. In the allergies there was a decrease in CMBC (concentration of moving blood cells) that was not seen in normals. The decrease in CMBC seen in allergies could be attributed to an increase in vascular permeability producing an interstitial edema, a well-known effect of histamine. After treatment with 1 week of intranasal steroid, most of the differences in the reaction pattern between normals and allergies had disappeared.

Grudemo H; Juto JE

2000-01-01

332

Laser-doppler-velocimetry measurements in a one and a half stage transonic test turbine with different angular stator-stator positions  

Energy Technology Data Exchange (ETDEWEB)

A one and a half stage transonic turbine was tested using a two component laser-doppler-velocimetry system. The measurements were carried out in order to record rotor phase resolved velocity, flow angle and turbulence distributions upstream and downstream of the second stator row at several different angular stator-stator positions (''clocking'' positions). Altogether, the measurements downstream of the second stator were performed for ten different clocking positions and upstream of the second stator for two different clocking positions. These different clocking positions have a significant influence on the flow field upstream and downstream of the second stator. Furthermore error estimation and a discussion of the tracer particle response are discussed. (orig.)

Schennach, Oliver; Woisetschlaeger, Jakob; Marn, Andreas; Goettlich, Emil [Graz University of Technology, Institute for Thermal Turbomachinery and Machine Dynamics, Graz (Austria)

2007-08-15

333

Pitot-tube flowmeter for quantification of airflow during sleep.  

Science.gov (United States)

The gold-standard pneumotachograph is not routinely used to quantify airflow during overnight polysomnography due to the size, weight, bulkiness and discomfort of the equipment that must be worn. To overcome these deficiencies that have precluded the use of a pneumotachograph in routine sleep studies, our group developed a lightweight, low dead space 'pitot flowmeter' (based on pitot-tube principle) for use during sleep. We aimed to examine the characteristics and validate the flowmeter for quantifying airflow and detecting hypopneas during polysomnography by performing a head-to-head comparison with a pneumotachograph. Four experimental paradigms were utilized to determine the technical performance characteristics and the clinical usefulness of the pitot flowmeter in a head-to-head comparison with a pneumotachograph. In each study (1-4), the pitot flowmeter was connected in series with a pneumotachograph under either static flow (flow generator inline or on a face model) or dynamic flow (subject breathing via a polyester face model or on a nasal mask) conditions. The technical characteristics of the pitot flowmeter showed that, (1) the airflow resistance ranged from 0.065 ± 0.002 to 0.279 ± 0.004 cm H(2)O L(-1) s(-1) over the airflow rates of 10 to 50 L min(-1). (2) On the polyester face model there was a linear relationship between airflow as measured by the pitot flowmeter output voltage and the calibrated pneumotachograph signal a (?(1) = 1.08 V L(-1) s(-1); ?(0) = 2.45 V). The clinically relevant performance characteristics (hypopnea detection) showed that (3) when the pitot flowmeter was connected via a mask to the human face model, both the sensitivity and specificity for detecting a 50% decrease in peak-to-peak airflow amplitude was 99.2%. When tested in sleeping human subjects, (4) the pitot flowmeter signal displayed 94.5% sensitivity and 91.5% specificity for the detection of 50% peak-to-peak reductions in pneumotachograph-measured airflow. Our data validate the pitot flowmeter for quantification of airflow and detecting breathing reduction during polysomnographic sleep studies. We speculate that quantifying airflow during sleep can differentiate phenotypic traits related to sleep disordered breathing. PMID:21178245

Kirkness, J P; Verma, M; McGinley, B M; Erlacher, M; Schwartz, A R; Smith, P L; Wheatley, J R; Patil, S P; Amis, T C; Schneider, H

2010-12-22

334

Pitot-tube flowmeter for quantification of airflow during sleep.  

UK PubMed Central (United Kingdom)

The gold-standard pneumotachograph is not routinely used to quantify airflow during overnight polysomnography due to the size, weight, bulkiness and discomfort of the equipment that must be worn. To overcome these deficiencies that have precluded the use of a pneumotachograph in routine sleep studies, our group developed a lightweight, low dead space 'pitot flowmeter' (based on pitot-tube principle) for use during sleep. We aimed to examine the characteristics and validate the flowmeter for quantifying airflow and detecting hypopneas during polysomnography by performing a head-to-head comparison with a pneumotachograph. Four experimental paradigms were utilized to determine the technical performance characteristics and the clinical usefulness of the pitot flowmeter in a head-to-head comparison with a pneumotachograph. In each study (1-4), the pitot flowmeter was connected in series with a pneumotachograph under either static flow (flow generator inline or on a face model) or dynamic flow (subject breathing via a polyester face model or on a nasal mask) conditions. The technical characteristics of the pitot flowmeter showed that, (1) the airflow resistance ranged from 0.065 ± 0.002 to 0.279 ± 0.004 cm H(2)O L(-1) s(-1) over the airflow rates of 10 to 50 L min(-1). (2) On the polyester face model there was a linear relationship between airflow as measured by the pitot flowmeter output voltage and the calibrated pneumotachograph signal a (?(1) = 1.08 V L(-1) s(-1); ?(0) = 2.45 V). The clinically relevant performance characteristics (hypopnea detection) showed that (3) when the pitot flowmeter was connected via a mask to the human face model, both the sensitivity and specificity for detecting a 50% decrease in peak-to-peak airflow amplitude was 99.2%. When tested in sleeping human subjects, (4) the pitot flowmeter signal displayed 94.5% sensitivity and 91.5% specificity for the detection of 50% peak-to-peak reductions in pneumotachograph-measured airflow. Our data validate the pitot flowmeter for quantification of airflow and detecting breathing reduction during polysomnographic sleep studies. We speculate that quantifying airflow during sleep can differentiate phenotypic traits related to sleep disordered breathing.

Kirkness JP; Verma M; McGinley BM; Erlacher M; Schwartz AR; Smith PL; Wheatley JR; Patil SP; Amis TC; Schneider H

2011-02-01

335

Factors affecting the performance of ultrasonic flowmeters  

Energy Technology Data Exchange (ETDEWEB)

A programme of work is currently underway at NEL to investigate and characterise the performance of liquid ultrasonic meters over a wide range of conditions. This paper presents the results of laboratory evaluations in addition to the initial results of combined flow and flowmeter modelling. Two-phase, oil/gas performance tests were conducted on commercially available meters of 4-inch nominal bore. Specific results have been selected to illustrate performance variations related to factors in meter design and operation. Two-phase, oil/water performance tests with water-cuts of up to 15 % were also conducted on the above meters. These results are presented in their entirety. The results show deviations from single-phase performance which vary for each meter design. Baseline calibration results for four commercially available clamp-on meters are presented. The results were obtained in good installation conditions on stainless steel pipes of 4-inch and 8-inch nominal bore. The results show different levels of accuracy associated with each meter and a general conformation with predicted behaviour. The final section of the paper presents results obtained by a systematic numerical method of determining the flow profile sensitivity of various meter configurations. The results provide quantitative confirmation of the reduced sensitivity of multipath designs to variations in the velocity profile. (author)

Brown, G.J.

1997-07-01

336

Study on the development of ultrasonic gas flowmeter  

Energy Technology Data Exchange (ETDEWEB)

Ultrasonic flowmeters have more advantages than the conventional method using pressure-difference. In these reasons, many advanced nations are already selling the commercial model. In RIST, we have been developed ultrasonic gas flow meter for the localization since a project was been contracted with POSCO in 1997. This paper describes a new ultrasonic gas flowmeter. This ultrasonic gas flowmeter is developed for accurate measurement of gases in a harsh environmental conditions. It is especially suited for measuring LDG, COG, BFG gases produced in iron and steel making process. In this study, we had developed the commercial model about the first tested model and applied a completed system to the POSCO gas line. Its performance has already well been proven by extensive field tests for several months in POSCO, iron and steel making company.

Hwang, Won Ho [Research Institute of Industrial Science and Technology, Pohang (Korea, Republic of); Park, Sang Gug [Uiduk Univ., Gyeongju (Korea, Republic of); Yang, Kyu Hong [POSCON, Pohang (Korea, Republic of); Jhang, Kyung Young [Hanyang Univ., Seoul (Korea, Republic of)

2001-07-01

337

High-rangeability ultrasonic gas flowmeter for monitoring flare gas.  

UK PubMed Central (United Kingdom)

A transit-time ultrasonic gas flowmeter for high-rangeability requirements, such as those encountered in flare-gas flow-metering, is presented. The concept of ray rescue angle for the orientation of the ultrasonic transducers in single-beam transit-time ultrasonic flowmeters is introduced to overcome the problem of ultrasonic beam drift in high-velocity flows. To overcome problems associated with noise at high velocities, a chirp signal is used. To preserve the accuracy of the meter at low velocities near zero flow, a combination of chirp and continuous-wave signals is used to interrogate the flow. Overall system performance is presented, based on results from extensive wind-tunnel tests.

Mylvaganam KS

1989-01-01

338

High-rangeability ultrasonic gas flowmeter for monitoring flare gas.  

Science.gov (United States)

A transit-time ultrasonic gas flowmeter for high-rangeability requirements, such as those encountered in flare-gas flow-metering, is presented. The concept of ray rescue angle for the orientation of the ultrasonic transducers in single-beam transit-time ultrasonic flowmeters is introduced to overcome the problem of ultrasonic beam drift in high-velocity flows. To overcome problems associated with noise at high velocities, a chirp signal is used. To preserve the accuracy of the meter at low velocities near zero flow, a combination of chirp and continuous-wave signals is used to interrogate the flow. Overall system performance is presented, based on results from extensive wind-tunnel tests. PMID:18284961

Mylvaganam, K S

1989-01-01

339

Study on the development of ultrasonic gas flowmeter  

International Nuclear Information System (INIS)

[en] Ultrasonic flowmeters have more advantages than the conventional method using pressure-difference. In these reasons, many advanced nations are already selling the commercial model. In RIST, we have been developed ultrasonic gas flow meter for the localization since a project was been contracted with POSCO in 1997. This paper describes a new ultrasonic gas flowmeter. This ultrasonic gas flowmeter is developed for accurate measurement of gases in a harsh environmental conditions. It is especially suited for measuring LDG, COG, BFG gases produced in iron and steel making process. In this study, we had developed the commercial model about the first tested model and applied a completed system to the POSCO gas line. Its performance has already well been proven by extensive field tests for several months in POSCO, iron and steel making company

2001-01-01

340

Project 6. 8: Laser-Doppler anemometry (LDA) in oil and coal dust flames. Preliminary final report phase I 1985-1989. Vorhaben 6. 8: Laser-Doppler-Anemometrie (LDA) in Oel- und Kohlenstaubflammen. Vorlaeufiger Abschlussbericht Phase I 1985-1989  

Energy Technology Data Exchange (ETDEWEB)

Within the framework of this project, speed and turbulence measurements were carried through in oil and coal dust flames by laser Doppler anemometry. First of all, a heavy-oil flame with a thermal capacity of 0.5 MW was measured. The burner used was a commercial multi-fuel burner manufactured by Messrs. Weishaupt. The speed profiles compared and investigated were those of two heavy-oil flames generated using different oil atomizing nozzles. The measurements in coal dust flames were carried through at the coal grinding and combustion plant set up in partial project no 3.1. Out of the different measuring programmes, this paper presents, by way of example, the results of a test programme concerned with investigating the impact of different inlet speeds of core air, primary air and secondary air of an industrial burner on the fluid flow and turbulence field, as well as on the course of combustion. The relative flames exhibited mean angular momentum and had a constant thermal capacity of 320 KW. A separate chapter deals briefly with the limits and problems of the use of laser Doppler anemometry in luminous flames. (orig.).

Brodbek, H.

1992-01-01

 
 
 
 
341

A self-retaining nasal flowmeter for preterm infants.  

Science.gov (United States)

A nasal flowmeter suitable for preterm infants is described. It is made from a commercially available nasal cannula and 400-mesh stainless steel screen. Low dead space (0.35 ml) and low resistance (1.3 cmH2O . 100 ml-1 . s) are advantages. Light weight and compact design have eliminated the need for extensive restraint of the subject. Also, the investigator need not hold the flowmeter in place. These features make accurate measurement of respiratory airflow and tidal volume possible during polygraphic monitoring studies lasting several hours. PMID:6445349

Brouillette, R T; Thach, B T

1980-03-01

342

A self-retaining nasal flowmeter for preterm infants.  

UK PubMed Central (United Kingdom)

A nasal flowmeter suitable for preterm infants is described. It is made from a commercially available nasal cannula and 400-mesh stainless steel screen. Low dead space (0.35 ml) and low resistance (1.3 cmH2O . 100 ml-1 . s) are advantages. Light weight and compact design have eliminated the need for extensive restraint of the subject. Also, the investigator need not hold the flowmeter in place. These features make accurate measurement of respiratory airflow and tidal volume possible during polygraphic monitoring studies lasting several hours.

Brouillette RT; Thach BT

1980-03-01

343

Basic doppler echocardiography  

Energy Technology Data Exchange (ETDEWEB)

This book contains 12 chapters. Some of the chapter titles are: An Introduction to Doppler; Pulsed and Continuous Wabe Doppler; The Doppler Examination; Doppler Evaluation of Valvular Regurgitation; Doppler Evaluation of Valvular Stenosis; and Pulsed Doppler Analysis of Human Fetal Blood Flow.

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

1986-01-01

344

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)

1986-01-01

345

Self-mixing laser Doppler vibrometry with high optical sensitivity application to real-time sound reproduction  

CERN Multimedia

Nanometre vibration measurement of an audio speaker and a highly sensitive sound reproduction experiment have been successfully demonstrated by a self-aligned optical feedback vibrometry technique using the self-mixing modulation effect in a laser-diode-pumped microchip solid-state laser. By applying nanometre vibrations to the speaker, which produced nearly inaudible music below 20 dB (200 mu Pa) sound pressure level, we could reproduce clear sound in real time by the use of a simple frequency modulated wave demodulation circuit with a -120 dB light-intensity feedback ratio.

Abe, K; Ko, J Y

2003-01-01

346

Antireflection-coated blue GaN laser diodes in an external cavity and Doppler-free indium absorption spectroscopy.  

UK PubMed Central (United Kingdom)

Commercially available GaN-based laser diodes were antireflection coated in our laboratory and operated in an external cavity in a Littrow configuration. A total tuning range of typically 4 nm and an optical output power of up to 30 mW were observed after optimization of the external cavity. The linewidth was measured with a beterodyne technique, and 0.8 MHz at a sweep time of 50 ms was obtained. The mode-hop-free tuning range was more than 50 GHz. We demonstrated the performance of the laser by detecting the saturated absorption spectrum of atomic indium at 410 nm, allowing observation of well-resolved Lamb dips.

Hildebrandt L; Knispel R; Stry S; Sacher JR; Schael F

2003-04-01

347

Proposal of Non Contact Inspection Method for Concrete Structures Using High-Power Directional Sound Source and Scanning Laser Doppler Vibrometer  

Science.gov (United States)

Maintenance for concrete structures such as buildings, bridges, and tunnels is necessary, because it is thought that a lot of them show deterioration. As a periodic inspection, a hammering test is the most popular method. However, it has several problems. One of the problems is that it is difficult to inspect the places where people cannot reach. Therefore, non contact inspection methods have been developed. As a non-contact inspection method, we propose a system consisting of a high-power directional sound source and a scanning laser doppler vibrometer (SLDV). In this method, an air-borne sound wave is used for the excitation of a concrete wall, and then the vibration velocities on the concrete wall are measured two-dimensionally by the SLDV. From the vibration velocity, defective parts can be detected. In this paper, we describe two types of experiment on the feasibility of our proposed method. In these experiments, concrete wall test pieces, which have artificial defects, are used. From the experimental results, we confirmed the effectiveness of our proposed method as a non contact inspection method for concrete structures.

Akamatsu, Ryo; Sugimoto, Tsuneyoshi; Utagawa, Noriyuki; Katakura, Kageyoshi

2013-07-01

348

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

2006-05-21

349

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

Energy Technology Data Exchange (ETDEWEB)

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.

Humeau, Anne [Groupe ISAIP-ESAIP, 18 rue du 8 mai 1945, BP 80022, 49180 Saint Barthelemy d' Anjou Cedex (France); Koitka, Audrey [Laboratoire de Physiologie et d' Explorations Vasculaires, Centre Hospitalier Universitaire d' Angers, 49033 Angers Cedex 01 (France); Abraham, Pierre [Laboratoire de Physiologie et d' Explorations Vasculaires, Centre Hospitalier Universitaire d' Angers, 49033 Angers Cedex 01 (France); Saumet, Jean-Louis [Laboratoire de Physiologie et d' Explorations Vasculaires, Centre Hospitalier Universitaire d' Angers, 49033 Angers Cedex 01 (France); L' Huillier, Jean-Pierre [Ecole Nationale Superieure d' Arts et Metiers (ENSAM), Laboratoire Procedes-Materiaux-Instrumentation (LPMI), 2 boulevard du Ronceray, BP 3525, 49035 Angers Cedex (France)

2004-03-07

350

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.

351

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

International Nuclear Information System (INIS)

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 (LDFRECG 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 LDFRECG nor with HRV. Moreover, the asymmetry index for LDF is markedly different from the ones of LDFRECG and HRV. The cardiac activity may therefore play a dominant role in the time irreversibility properties of LDF signals. (paper)

2012-07-07

352

Determination of the electrokinetic potential of Rhizobium leguminosarum bv trifolii Rt24.2 using Laser Doppler Velocimetry--a methodological study.  

Science.gov (United States)

Electrokinetic potential (?, zeta potential) is one of the parameters which characterize the physicochemical properties of the bacterial cell envelope. The term is often used in the context of adhesiveness of bacteria and biofilm formation. This work presents the methodological aspects of zeta potential determination in strain Rt24.2 of Rhizobium leguminosarum using Laser Doppler Velocimetry combined with Phase Analysis Light Scattering and changed electric field techniques. The influence of media (0.9% NaCl, 0.2% NaCl, TY, GYM, 79CA, 20E and M1), temperature of measurement, number of measurement repetitions, phase of culture, concentration of bacteria, and storage at low temperature on the value of electrokinetic potential was investigated and a comparison was drawn between live and dead bacteria. All of those factors modified the zeta potential, showing that these parameters should be precisely specified in studies of bacterial electrokinetic potential, which is not always done. The obtained results also indicated that the zeta potential of Rhizobium leguminosarum should be determined directly in samples without storage at a defined bacterial density. The measurement should be done only once in a sample inserted into the cell of a measuring device to eliminate changes occurring in the sample (increase of electrolytic conductivity) under the electric field used. PMID:21397639

Cie?la, Jolanta; Bieganowski, Andrzej; Janczarek, Monika; Urbanik-Sypniewska, Teresa

2011-03-21

353

Determination of the electrokinetic potential of Rhizobium leguminosarum bv trifolii Rt24.2 using Laser Doppler Velocimetry--a methodological study.  

UK PubMed Central (United Kingdom)

Electrokinetic potential (?, zeta potential) is one of the parameters which characterize the physicochemical properties of the bacterial cell envelope. The term is often used in the context of adhesiveness of bacteria and biofilm formation. This work presents the methodological aspects of zeta potential determination in strain Rt24.2 of Rhizobium leguminosarum using Laser Doppler Velocimetry combined with Phase Analysis Light Scattering and changed electric field techniques. The influence of media (0.9% NaCl, 0.2% NaCl, TY, GYM, 79CA, 20E and M1), temperature of measurement, number of measurement repetitions, phase of culture, concentration of bacteria, and storage at low temperature on the value of electrokinetic potential was investigated and a comparison was drawn between live and dead bacteria. All of those factors modified the zeta potential, showing that these parameters should be precisely specified in studies of bacterial electrokinetic potential, which is not always done. The obtained results also indicated that the zeta potential of Rhizobium leguminosarum should be determined directly in samples without storage at a defined bacterial density. The measurement should be done only once in a sample inserted into the cell of a measuring device to eliminate changes occurring in the sample (increase of electrolytic conductivity) under the electric field used.

Cie?la J; Bieganowski A; Janczarek M; Urbanik-Sypniewska T

2011-06-01

354

Comparative potency of formulations of mometasone furoate in terms of inhibition of ?PIRHR? in the forearm skin of normal human subjects measured with laser doppler velocimetry  

Directory of Open Access Journals (Sweden)

Full Text Available BACKGROUND AND AIMS: Topical glucocorticoid formulations are widely used for effective treatment and control of a variety of dermatoses. Mometasone furoate is a newer corticoid that has high potency but low systemic toxicity. Pharmaceutical factors are known to significantly influence potency and systemic absorption of topically applied glucocorticoids. We studied the potency of "Elocon", a topical formulation of mometasone furoate, compared with two other branded formulations of the same corticoid. METHODS: Corticoid potency was measured by employing a pharmacodynamic parameter of an inhibitory effect of the corticoid on post-ischemic-reactive-hyperemic-response (PIRHR) in human forearm skin under occlusive dressing. The PIRHR was expressed in terms of % increase in the skin blood flow (SBF) as measured with laser doppler velocimetry (LDV). RESULTS : All three active branded formulations of mometasone furoate produced significant inhibition of PIRHR. The AUC(0-2min) of PIRHR was ( Mean ± SEM ), Control = 213.52 ± 11.80, Placebo = 209.77 ± 19.31, Formulation A = 119.83 ± 13.71, Formulation C = 53.67 ± 4.85 and Formulation D = 111.46 ± 22.87. Formulation "C" exhibited significantly higher topical anti-inflammatory potency than formulations "A" or "D". CONCLUSIONS: Thus, branded formulations of the same glucocorticoid, mometasone furoate significantly differed in their topical anti-inflammatory potency. "Elocon" was significantly more potent than the two other branded formulations studied.

Kulhalli Prabhakar; Chevli Tejal; Karnik Rupal; Sheth Manish; Mulgaonkar Nitin

2005-01-01

355

LDV measurements and computation of a turbulent circular jet placed non-concentrically in a confining pipe[Laser Doppler Velocimetry  

Energy Technology Data Exchange (ETDEWEB)

Quantitative and nonintrusive fluid velocity and turbulence measurements obtained using laser Doppler velocimetry (LDV) in a circular jet that is positioned nonconcentrically in a confining pipe are presented. The experimental findings are compared with the results obtained by the finite-element computational simulation of the flow. The measured and predicted contours of the time-averaged axial velocity reveal the presence of a three-dimensional (3-D) asymmetric reverse-flow region, with its radial and circumferential extent depending on the axial position and the eccentricity ratio. Due to the weakened radial mixing and spreading of the jet for the higher eccentricities, the transition to the fully developed state is delayed for the high eccentricity cases. Measured and predicted contours of the axial turbulence fluctuations exhibit the ringlike distribution, although it is observed in an offset position for a given eccentricity ratio. At the downstream stations, the ringlike distribution tends to become more symmetric. The basic phenomena of flow reversal, preferential mixing, and shear layer growth are recovered by the computational predictions based on the high-Reynolds-number turbulence model. The time-averaged velocity measurements compare well with the predictions, whereas only qualitative comparison can be observed between the measured and predicted turbulence fluctuations.

Khodadadi, J.M.; Wright, B.L.; Lan, X.K.

1999-10-01

356

Two-point laser Doppler velocimetry measurements in a Mach 1.2 cold supersonic jet for statistical aeroacoustic source model  

Energy Technology Data Exchange (ETDEWEB)

Single and multi-point laser Doppler velocimetry measurements performed in a cold Mach 1.2 jet flow are used to assess those properties of the aerodynamic field most relevant in the generation of turbulence mixing noise. Single point measurements yield mean velocity profiles, turbulence intensity profiles and power spectral densities of both the velocity and Reynolds stress fields at seven axial stations between the jet exit and the end of the potential core. The longitudinal components of the second-order and fourth-order two-point velocity correlation tensor are obtained from a series of multi-point LDV measurements, whence a cartography of integral space and time scales, convection velocities and acoustic compactness is effected. These results are used to examine differences between subsonic and supersonic jet aerodynamics in terms of their sound generating potential. Finally analytical expressions are proposed for the spatial and temporal parts of the longitudinal correlation coefficient function. These are scaled using the integral space and time scales of the velocity and Reynolds stress fields, and excellent agreement is found with experimentally determined functions. (orig.)

Kerherve, F.; Jordan, P.; Gervais, Y.; Valiere, J.C.; Braud, P. [Laboratoire d' Etudes Aerodynamiques, Batiment K, UMR Centre National de la Recherche Scientifique 6609, 40 Avenue du Recteur Pineau, 86000, Poitiers (France)

2004-09-01

357

Local drag reduction due to injection of polymer solutions into turbulent flow in a pipe; part II: laser-Doppler measurements of turbulent structure  

Energy Technology Data Exchange (ETDEWEB)

Aqueous solutions of polyethyleneoxide (Polyox WSR-301) were injected into a pipe flow through either a small tube at the center line or an annular slot in the wall. The solution contained polymer at an injection concentration of 1,000 wppm. Injection into water flow with a Reynolds number Re = 3.5 X 10/sup 4/ was at a rate which gave a mean polymer concentration of 5.0 wppm in the water flow. A laser-Doppler anemometer (LDA) was used to measure the streamwise turbulent velocity at various radial positions and at several stations downstream from the injection point. Results were obtained for mean velocity and intensity profiles; autocorrelations; and one-dimensional energy spectra. The mean bursting period was determined using the ''short-sampling-time'' autocorrelation method. Changes in all these quantities due to polymer injection were found to depend on the amount of local drag reduction at that particular downstream station but were independent of the local polymer concentration at the measuring point.

McComb, W.D.; Rabie, L.H.

1982-07-01

358

The impact of laser Doppler imaging on the early decision-making process for surgical intervention in adults with indeterminate burns.  

UK PubMed Central (United Kingdom)

OBJECTIVE: We aimed to analyze whether laser Doppler imaging (LDI) can lead to earlier decision-making regarding the need for surgery in adults with indeterminate burns. METHODS: In a retrospective cohort study, we developed a prediction model for surgery in adults with indeterminate burns. Patient data (n=101) from January 2007 to December 2009 were used for model development, and those (n=40) from January 2010 to October 2010 for external validation. RESULTS: Between non-surgical and surgical groups, there were significant differences for mean age (p=0.009), % total body surface area burn (p=0.016), site of burn wound (p=0.033), and mean perfusion units (PU) (p<0.001). Multiple logistic regression showed that only the mean PU differed significantly between the groups. The area under the curve (AUC) of the equation derived from multiple logistic regression was 0.938, which did not differ from that of the mean PU alone (0.931; p=0.453). Using a cut-off point of 154.7PU, the sensitivity of LDI was 78.3% and the specificity was 92.7%. This cut-off point also yielded a sensitivity of 77.8% and specificity of 95.5% in the external validation dataset. CONCLUSION: LDI can help make a decision for surgery in the early stages of care for adults with indeterminate burns.

Park YS; Choi YH; Lee HS; Moon DJ; Kim SG; Lee JH; Cho JK; Yoon CJ

2013-06-01

359

Decision-making in DIEP and ms-TRAM flaps: the potential role for a combined laser Doppler spectrophotometry system.  

UK PubMed Central (United Kingdom)

BACKGROUND: Three-dimensional (3D)-imaging modalities for pre-operative mapping of perforators in DIEP and ms-TRAM flap surgery are well established. While zonal perfusion of such flaps has been extensively studied pre-, intra- and post-operatively, the role of objective perfusion assessment for decision making between different possible perforator configurations has not been investigated yet. In this study, a combined lased Doppler spectrophotometry (CLDS) system was applied intra-operatively to support the surgeon's decision-making process. METHODS: In this prospective study, 25 consecutive unilateral abdominal flaps were included. Computed tomographic angiography (CTA) was performed prior to surgery. By CLDS the post-capillary oxygen saturation, relative haemoglobin content and relative bloodflow were determined at different time points and in four standardised zones in dependence of different possible perforator/pedicle vessel configurations (with selective clamping of different perforators and/or the superficial inferior epigastric vein). Results were correlated with clinical findings and late results were evaluated after 6-16 months. RESULTS: Ninety-six percent of the flaps survived. No significant fat necrosis was observed. While there was a high correlation between clinical findings and CLDS results, CLDS was more sensitive in identification of venous congestion of DIEP flaps. The technique helped to identify the dominant perforator(s) in flaps where perfusion patterns were unclear. CLDS influenced intra-operative decision making in five cases (two venous and one arterial in-flap anastomosis and inclusion of additional perforators in two flaps). CONCLUSION: Intra-operative use of CLDS helps to objectively determine perfusion patterns in abdominal flaps. CLDS might be applicable in 'complex' abdominal flaps (e.g., after previous abdominal surgery or when preoperative CTA does not provide conclusive results) and supports, in these cases, intra-operative decision-making.

Beier JP; Horch RE; Arkudas A; Dragu A; Schmitz M; Kneser U

2013-01-01

360

Observation of sub-Doppler absorption in the /Lambda-type three-level Doppler-broadened cesium system  

CERN Document Server

Thanks to the atomic coherence in coupling laser driven atomic system, sub-Doppler absorption has been observed in Doppler-broadened cesium vapor cell via the /Lambda-type three-level scheme. The linewidth of the sub-Doppler absorption peak become narrower while the frequency detuning of coupling laser increases. The results are in agreement with the theoretical prediction by G. Vemuri et al.[PRA,Vol.53(1996) p.2842].

Wang, J; Yan, S; Liu, T; Zhang, T; Wang, Junmin; Wang, Yanhua; Yan, Shubin; Liu, Tao; Zhang, Tiancai

2003-01-01

 
 
 
 
361

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

Energy Technology Data Exchange (ETDEWEB)

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.

Araki, H.; Uno, O.; Ozaki, Y.; Oda, M.

1987-05-01

362

A positive displacement flowmeter for measurement of COM slurries. [Coal-oil mixtures  

Energy Technology Data Exchange (ETDEWEB)

Since COM (coal oil mixture) consists of about 50% coal particles mixed together with fuel oil, it has been thought that measurement of COM flow rates is impossible by means of positive displacement flowmeters. However, the Nitto Seiko Company has successfully developed the SF and CR flowmeters based on a new measurement mechanism. These meters are now in operation. The SF flowmeter comprises a main rotor, three vanes and two sub-rotors. The CR flowmeter has a rotary piston construction. Explanations are given of the principle and construction of both meters.

Yoshida, K.

1983-01-01

363

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.

2003-01-01

364

Left coronary arterial blood flow: Noninvasive detection by Doppler US  

Energy Technology Data Exchange (ETDEWEB)

Continuous wave (CW) and pulsed Doppler ultrasound studies with spectral analysis were used to detect the left coronary arterial blood flow in patients who were undergoing routine echocardiography. The pulmonary artery is a stable ultrasonic landmark from which detection of the blood flow can be effected. The left coronary artery can be distinguished by its blood flow toward the cardiac apex and by specific, functional flow features. Flow patterns vary among the left main, circumflex, and anterior descending arteries; patterns also vary with respiration cycles. In the present study, coronary arterial blood flow was detected in 58 of 70 patients (83%). Findings were validated by selectively injecting an agitated saline contrast medium into the left coronary artery and, in another study, by comparing human Doppler phasic flow waveforms with electromagnetic flowmeter recordings obtained in dogs.

Gramiak, R.; Holen, J.; Moss, A.J.; Gutierrez, O.H.; Picone, A.L.; Roe, S.A.

1986-06-01

365

Electromagnetic flowmeters: a state of the art review  

Energy Technology Data Exchange (ETDEWEB)

The basic problems arising in the design of electromagnetic flowmeters are described and the ways in which these are overcome are explained. The problems include (1) spurious DC or low frequency potentials across the electrodes, (2) transformer signals associated with the need to use a changing magnetic field, (3) the difficulty in predicting sensitivity and (4) velocity profile effects. The methods of overcoming these problems include AC sine wave or square wave magnet excitation, phase sensitive detection, use of Hall probe, search soil, feedback, magnetic field shaping and the use of contactless electrodes. Ways in which future electromagnetic flowmeters may be designed to extend the range of liquids that could be metered, to improve the accuracy of measurement and to incorporate self-checking means are indicated. 22 references.

Hemp, J.; Sanderson, M.L.

1981-01-01

366

A study of doppler waveform using pulsatile flow model  

Energy Technology Data Exchange (ETDEWEB)

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

Chung, Hye Won [Seoul City Boramae Hospital, Seoul (Korea, Republic of); Chung, Myung Jin; Park, Jae Hyung; Chung, Jin Wook; Lee, Dong Hyuk; Min, Byoung Goo [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

1997-08-01

367

The challenge of realistic testing of multiphase flowmeters  

Energy Technology Data Exchange (ETDEWEB)

Multiphase flowmeters is new technology for the oil industry, and needs to be tested under realistic conditions to prove their performance. The complex nature of multiphase flow, means that test conditions in a laboratory may not necessarily represent the real flow conditions at a field installation. As a consequence, severe field testing is also required to gain experience with the meters and qualify them for field applications.

Sten-Halvorsen, V. [Kongsberg Offshore A.S (Norway)

1995-12-31

368

Wide beam ultrasonic flowmeter; Waido bimu gata choonpa ryuryokei  

Energy Technology Data Exchange (ETDEWEB)

A conventional clamp-on ultrasonic flowmeter has an advantage to be able to set up for existing pipe, on the other hand, has a problem that the determination of transit path of ultrasonic waves is complex, because there is a pipe wall on the transit path. Namely, in the point sound source model which was used so far when the determination of transit path of ultrasonic waves, the compensation for the change of transit path which was caused by the change of sound velocity on prism and fluids due to the temperature variation was insufficient. Authors are studying this problem by a spatial frequency analysis. The transit path depends on the conditions of incident waves; frequency, incident angle, beam width and so forth. Especially, plate mode excitation affects on the transit path seriously, however, it was found that a wide beam would be very effective in reducing the effect due to the path mode excitation. The wide beam ultrasonic flowmeter provides a measurement with high accuracy, even if temperature changes in transit path would occur. This new flowmeter can be applied to any fluids whose sound velocities are unknown. 6 refs., 11 figs., 1 tab.

Motegi, R.; Sato, T.; Takeuchi, S.; Kashiwase, Y. [Tokimec Inc., Tokyo (Japan). R and C Center; Chubachi, N. [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1993-07-31

369

A newly developed borehole flowmeter technology for heterogeneous aquifers  

International Nuclear Information System (INIS)

Extensive borehole flowmeter tests were performed at 37 fully-screened wells on a one-hectare test site to characterize the three-dimensional hydraulic conductivity field of an alluvial aquifer with a ?lnK of 4.7. During the site investigations, several major advancements with respect to borehole flowmeter technology were developed. The milestones included: (1) the development of a field-durable electromagnetic borehole flowmeter with a lower detection limit of 0.1 l/min; (2) the realization of the importance of the pumping rate with respect to the calculated value for the depth-averaged hydraulic conductivity; and (3) an evaluation of alternative methods for calculating the depth-averaged hydraulic conductivity. The predicted three-dimensional hydraulic conductivity field was compared to the results of 10 small-scale (3 to 7 m) tracer tests, information about the depositional history of the aquifer, and the results of three large-scale aquifer tests. The hydraulic conductivity data predict the major features of the tracer breakthrough curves, maps the outline of a former river meander in an aerial photograph, and leads to a geometric mean consistent with the average hydraulic conductivity of the aquifer. (Author) (14 refs., 15 figs., 2 tabs.)

1990-01-01

370

The doppler ultrasound. La ecografia Doppler  

Energy Technology Data Exchange (ETDEWEB)

The discovery and development of Doppler ultrasound has had a great influence on Medical practice since it allows the noninvasive study of vascular pathology, both arterial and venous, as well as the flow patterns of the different parenchyma. This article deals with the principles, limitations and interpretation of the Doppler signal, as well as the different Doppler ultrasound systems routinely employed in Medicine.

Contreras Cecilia, E.; Lozano Setien, E.; Hernandez Montero, J.; Ganado Diaz, T.; Jorquera Moya, M.; Blasco Pascual, E. (Hospital Universitario San Carlos. Madrid (Spain))

1994-01-01

371

Laminar microvascular flow, measured by means of laser Doppler flowmetry, during the prodromal stages of black walnut-induced laminitis in horses.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To measure changes in laminar microvascular blood flow (LMBF) over time in healthy horses and horses in the prodromal stage of black walnut-induced laminitis and to determine the effects of glyceryl trinitrate application on LMBF in horses with acute laminitis. ANIMALS: 10 healthy adult horses. PROCEDURE: Laser Doppler flowmetry was used to measure LMBF Baseline measurements were obtained, horses were given deionized water via a nasogastric tube, and measurements were obtained hourly for 12 hours. Twenty-four hours later, baseline measurements were again obtained, and horses were given black walnut extract. Measurements were obtained hourly for 12 hours or until development of Obel grade-3 laminitis. At this time, 5 horses were treated with phenylbutazone, and the other 5 were treated with phenylbutazone and glyceryl trinitrate, and measurements were obtained hourly for an additional 12 hours. RESULTS: LMBF was significantly decreased 1 and 2 hours after administration of the black walnut extract but then returned to near-baseline values for the next 6 hours. Eight hours after extract administration, there was a second significant decrease in LMBF that persisted until the end of the study. Glyceryl trinitrate had no effect on LMBF. Clinical signs of laminitis developed 8 to 12 hours after extract administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in horses with black walnut-induced laminitis, there is an early decrease in LMBF followed by reperfusion prior to onset of clinical signs. Treatment with glyceryl trinitrate after development of clinical signs of laminitis did not have a significant effect on LMBF.

Adair HS 3rd; Goble DO; Schmidhammer JL; Shires GM

2000-08-01

372

Burn wound healing time assessed by laser Doppler imaging (LDI). Part 1: Derivation of a dedicated colour code for image interpretation.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Laser Doppler imaging produces a colour-coded image of dermal blood flow, which can be used to quantify the inflammatory response in a burn. The original colour palette had arbitrary boundaries, which inexperienced clinicians found difficult to interpret. The aim of this study was to define clinically useful boundaries that would assist in the prediction of burn healing potential. METHOD: We conducted a prospective, multi-centre study of burns in adults and children. LDI scans were performed between 48 h and 5 days after injury. The burns were assessed clinically and photographed on day of scan, day 14 and day 21 post-injury. Areas healed at day 14, healed between day 14 and 21 and unhealed at day 21 were identified on the LDI scan. The flow values for the pixels in these regions were analysed to calculate boundaries between the three healing categories. RESULTS: We recruited 137 patients (ages 1-88 years, 65% male); 392 LDI scans contained 433 different burn sites; 109 regions of interest were studied. Analysis allowed us to define ranges for the three healing categories: HP14 colour coded red, >600 PU; HP14-21, yellow, 260-440 PU; HP>21, blue, <200 PU; separated by two overlap regions pink, 440-600 PU and green, 200-260 PU. Blue was subdivided to show the very high association between LDI<140 PU and non-healing at day 21. CONCLUSION: We have devised a new colour palette for LDI burn imaging based on healing times of a series of burns. Validation of this palette is described separately, in Part 2.

Pape SA; Baker RD; Wilson D; Hoeksema H; Jeng JC; Spence RJ; Monstrey S

2012-03-01

373

Laser Doppler velocimetry measurements of flow within the cylinder of a motored two-stroke cycle engine - comparison with some computational fluid dynamic predictions  

Energy Technology Data Exchange (ETDEWEB)

This study was carried out to assess the ability of a computational fluid dynamics (CFD) code to predict the scavenging flow in the cylinder of a two-stroke cycle engine. Predictions were obtained from a CFD simulation of the flow within the cylinder. Due to the apparent symmetry of the engine port layout, only half of the cylinder volume was modelled. Boundary conditions for the CFD model were obtained from experimentally measured pressure-time histories in the crankcase and exhaust. The two-stroke cycle engine was modified to allow laser Doppler velocimetry (LDV) measurements to be made of the in-cylinder flow. The engine was operated under motoring conditions at 500 r/min with a delivery ratio of 0.7. Although the engine scavenge port layout was geometrically symmetrical, an asymmetrical flow field was identified in the cylinder. As a result of this, a direct comparison of the in-cylinder LDV measured and CFD computed results was not possible. However, LDV and CFD results for the in-cylinder flow are presented to help highlight the dissimilarity between the measured and predicted flow fields. Two-dimensional LDV measurements were made in the cylinder at the transfer ports for a portion of the cycle. A comparison of these LDV measurements with CFD predictions of the in-cylinder velocities at the same locations showed that the CFD model could replicate reasonably well the general trend of the flow. The measured cylinder averaged turbulent kinetic energy was compared with that of the CFD model. The qualitative trend of the overall turbulence generating capacity of the engine was well replicated by the CFD model. (Author)

Creaven, J.P.; Fleck, R.; Kenny, R.G.; Cunningham, G. [Queen' s Univ., School of Mechanical and Manufacturing Engineering, Belfast, Northern Ireland (United Kingdom)

2003-06-01

374

Comparative velocity investigations in cerebral arteries and aneurysms: 3D phase-contrast MR angiography, laser Doppler velocimetry and computational fluid dynamics.  

Science.gov (United States)

In western populations, cerebral aneurysms develop in approximately 4% of humans and they involve the risk of rupture. Blood flow patterns are of interest for understanding the pathogenesis of the lesions and may eventually contribute to deciding on the most efficient treatment procedure for a specific patient. Velocity mapping with phase-contrast magnetic resonance angiography (PC-MRA) is a non-invasive method for performing in vivo measurements on blood velocity. Several hemodynamic properties can either be derived directly from these measurements or a flow field with all its parameters can be simulated on the basis of the measurements. For both approaches, the accuracy of the PC-MRA data and subsequent modeling must be validated. Therefore, a realistic transient flow field in a well-defined patient-specific silicone phantom was investigated. Velocity investigations with PC-MRA in a 3 Tesla MR scanner, laser Doppler velocimetry (LDV) and computational fluid dynamics (CFD) were performed in the same model under equal flow conditions and compared to each other. The results showed that PC-MRA was qualitatively similar to LDV and CFD, but showed notable quantitative differences, while LDV and CFD agreed well. The accuracy of velocity quantification by PC-MRA was best in straight artery regions with the measurement plane being perpendicular to the primary flow direction. The accuracy decreased in regions with disturbed flow and in cases where the measurement plane was not perpendicular to the primary flow. Due to these findings, it is appropriate to use PC-MRA as the inlet and outlet conditions for numerical simulations to calculate velocities and shear stresses in disturbed regions like aneurysms, rather than derive these values directly from the full PC-MRA measured velocity field. PMID:19412933

Hollnagel, Dorothea I; Summers, Paul E; Poulikakos, Dimos; Kollias, Spyros S

2009-10-01

375

Comparative velocity investigations in cerebral arteries and aneurysms: 3D phase-contrast MR angiography, laser Doppler velocimetry and computational fluid dynamics.  

UK PubMed Central (United Kingdom)

In western populations, cerebral aneurysms develop in approximately 4% of humans and they involve the risk of rupture. Blood flow patterns are of interest for understanding the pathogenesis of the lesions and may eventually contribute to deciding on the most efficient treatment procedure for a specific patient. Velocity mapping with phase-contrast magnetic resonance angiography (PC-MRA) is a non-invasive method for performing in vivo measurements on blood velocity. Several hemodynamic properties can either be derived directly from these measurements or a flow field with all its parameters can be simulated on the basis of the measurements. For both approaches, the accuracy of the PC-MRA data and subsequent modeling must be validated. Therefore, a realistic transient flow field in a well-defined patient-specific silicone phantom was investigated. Velocity investigations with PC-MRA in a 3 Tesla MR scanner, laser Doppler velocimetry (LDV) and computational fluid dynamics (CFD) were performed in the same model under equal flow conditions and compared to each other. The results showed that PC-MRA was qualitatively similar to LDV and CFD, but showed notable quantitative differences, while LDV and CFD agreed well. The accuracy of velocity quantification by PC-MRA was best in straight artery regions with the measurement plane being perpendicular to the primary flow direction. The accuracy decreased in regions with disturbed flow and in cases where the measurement plane was not perpendicular to the primary flow. Due to these findings, it is appropriate to use PC-MRA as the inlet and outlet conditions for numerical simulations to calculate velocities and shear stresses in disturbed regions like aneurysms, rather than derive these values directly from the full PC-MRA measured velocity field.

Hollnagel DI; Summers PE; Poulikakos D; Kollias SS

2009-10-01

376

The effect of stents on intra-aneurysmal hemodynamics: in vitro evaluation of a pulsatile sidewall aneurysm using laser Doppler anemometry.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Hemodynamic modification by means of flow diversion is increasingly used for treatment of intracranial aneurysms. Despite of promising results, there is still a paucity of methods to reliably predict long-term success of this technique. Laser Doppler anemometry (LDA) can be used to quantify the influence of stents on intra-aneurysmal flow in vitro. METHODS: All experiments were performed with a pulsatile model of a sidewall aneurysm. A physiologic flow was created with a circulatory experimental setup, and a transparent non-Newtonian glycerol-water solution was used to substitute human blood. Flow velocity was measured with a one-component LDA system, recording flow components parallel and perpendicular to the parent vessel. Three different stents (Solitaire, Silk, Phenox flow diverter) were deployed over the aneurysm neck, respectively. RESULTS: Flow reduction was 67.59% (inflow zone), 9.65% (dome) and 37.94% (outflow zone) by the Solitaire stent. The Silk stent reduced the flow by 58.15% (inflow zone), 89.06% (dome) and 90.06% (outflow zone). The Phenox flow diverter reduced the flow by 96.76% (inflow zone), 90% (dome) and 90.91% (outflow zone) when positioned with narrow stent struts but increased the velocity of up to seven times compared to the unstented model when placed with loose strut packing in the proximal part of the aneurysm. CONCLUSION: LDA is a feasible method to quantify intra-aneurysmal flow and flow reduction efficacy of stents in vitro. Flow reduction was negligible with a standard self-expanding stent. For dedicated flow diverters, it depended both on stent design and on appropriate positioning.

Dorn F; Niedermeyer F; Balasso A; Liepsch D; Liebig T

2011-04-01

377

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Serdar Gundogdu; Ozge Sahin

378

Comparison of velocity-log data collected using impeller and electromagnetic flowmeters  

Science.gov (United States)

Previous studies have used flowmeters in environments that are within the expectations of their published ranges. Electromagnetic flowmeters have a published range from 0.1 to 79.0 m/min, and impeller flowmeters have a published range from 1.2 to 61.0 m/min. Velocity-log data collected in five long-screened production wells in the Pleasant Valley area of southern California showed that (1) electromagnetic flowmeter results were comparable within ??2% to results obtained using an impeller flowmeter for comparable depths; (2) the measured velocities from the electromagnetic flowmeter were up to 36% greater than the published maximum range; and (3) both data sets, collected without the use of centralizers or flow diverters, produced comparable and interpretable results. Although either method is acceptable for measuring wellbore velocities and the distribution of flow, the electromagnetic flowmeter enables collection of data over a now greater range of flows. In addition, changes in fluid temperature and fluid resistivity, collected as part of the electromagnetic flowmeter log, are useful in the identification of flow and hydrogeologic interpretation.

Newhouse, M. W.; Izbicki, J. A.; Smith, G. A.

2005-01-01

379

Airflow study of pathologic larynges using a hot wire flowmeter.  

UK PubMed Central (United Kingdom)

Two aspects of laryngeal airflow, constant flow rate (DC) and alternating flow rate (AC), were examined in patients with vocal cord paralysis, acute laryngitis, and vocal cord polyps using the hot wire flowmeter. Vocal cord paralysis was characterized by a large DC with a small AC/DC percentage, and acute laryngitis showed a normal DC in spite of a small AC/DC percentage. No consistent finding was observed for the laryngeal polyp. Simultaneous measurement of both parameters was thought to better define the physiologic correlates of hoarseness in various laryngeal disorders.

Kitajima K

1985-03-01

380

A pulsed phase measurement ultrasonic flowmeter for medical gases.  

Science.gov (United States)

Pneumotachometers are used to measure instantaneous flowrate in the respiratory gas streams. The presently available devices suffer from lack of linearity, slow response times, and gas density sensitivity. A new design of an ultrasonic gas flowmeter is presented in this paper: We investigate the acoustic characteristics of ring and piston shaped transducers, and describe a sampling method to avoid the error due to reflection. A microcomputer is used to overcome the 360 degrees detection ambiguity problem associated with phase detection technique. This design has been tested in clinical settings and has been shown to give linear response, independent of gas density, and to have a wide dynamic range. PMID:6240213

Kou, A H; Peickert, W R; Polenske, E E; Busby, M G

1984-01-01

 
 
 
 
381

A pulsed phase measurement ultrasonic flowmeter for medical gases.  

UK PubMed Central (United Kingdom)

Pneumotachometers are used to measure instantaneous flowrate in the respiratory gas streams. The presently available devices suffer from lack of linearity, slow response times, and gas density sensitivity. A new design of an ultrasonic gas flowmeter is presented in this paper: We investigate the acoustic characteristics of ring and piston shaped transducers, and describe a sampling method to avoid the error due to reflection. A microcomputer is used to overcome the 360 degrees detection ambiguity problem associated with phase detection technique. This design has been tested in clinical settings and has been shown to give linear response, independent of gas density, and to have a wide dynamic range.

Kou AH; Peickert WR; Polenske EE; Busby MG

1984-01-01

382

On the Traceability of Accuracy of Ultrasonic Flowmeter  

International Nuclear Information System (INIS)

Time-of-flight ultrasonic flowmeters have been widely used these days in industry. It is however in suspicion if its high accuracy is traceable to the national standard. It was made clear why traceability cannot be guaranteed from a fluid mechanical point of view. The main reason is a difference of flow configuration between the flow standard and the measurement position on-site. The concept of 'Facility Factor' is introduced and it is concluded that the 'Profile Factor' is not sufficient for correcting the meter reading. It is discussed that measurement of velocity profile on-site is essentially required. (author)

2006-01-01

383

Contact-free sensor for vortice-separating flowmeters  

International Nuclear Information System (INIS)

The flowmeter of the vortese type has got a magnet-dependent element as a sensor. The fluid to be measured is streaming through a flow pipe which has got an obstacle unit generating vortices. These vortices cause a swingable section to vibrate with a corresponding frequency. The vibrations are picked up by the sensor producing a signal with a frequency proportional to the flow rate of the fluid. In order to achieve this the sensor consists of a megnetic resistance, a field plate or a Hall-effect element and the approximation element from soft iron fixed to the swingable section. (DG)

1977-01-01

384

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 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.

2005-01-01

385

Wind sensing demonstration of more than 30km measurable range with a 1.5?m coherent Doppler lidar which has the laser amplifier using Er,Yb:glass planar waveguide  

Science.gov (United States)

Recently, we have developed the high output power laser amplifier using Er,Yb:glass planar waveguide in order to increase the measurable range of our 1.5 ?m coherent Doppler LIDAR (CDL). In this paper, we introduce this development and demonstration of a long range wind sensing using the developed system. The transmitted pulse has a peak power of 2.4 kW and a width of 580 ns (i.e. pulse energy of 1.4 mJ) with a pulse repetition frequency of 4 kHz, in addition to a nearly diffraction limited beam quality. With this laser amplifier, we demonstrate the measurable range of more than 30 km. According to our own research, this is the longest measurable range demonstration for wind sensing CDLs.

Kameyama, Shumpei; Sakimura, Takeshi; Watanabe, Yojiro; Ando, Toshiyuki; Asaka, Kimio; Tanaka, Hisamichi; Yanagisawa, Takayuki; Hirano, Yoshihito; Inokuchi, Hamaki

2012-11-01

386

Doppler-free Laser Spectroscopy  

Science.gov (United States)

Instructional material presented at W34 at the Beyond the First Year Laboratory conference and part of W36 âAdvanced & Intermediate Laboratoriesâ at the 2012 AAPT summer meeting. A laboratory manual, a complete list of equipment needed, and experimental tips are included. The main goals for the experiments are: ⢠To measure hyperfine splitting of atomic energy levels in 87Rb. ⢠To become familiar with optical techniques ⢠To become familiar with Michelson interferometry and measurement calibration

Hudek, Laboratory P.

2013-02-13

387

Wet gas testing with the V-Cone flowmeter  

Energy Technology Data Exchange (ETDEWEB)

This paper discusses a series of tests conducted at the Southwest Research Institute for McCrometer Inc. Southwest Research in San Antonio, Texas has developed a wet gas testing loop using nitrogen gas and water. McCrometer contracted with Southwest Research to conduct a series of tests to evaluate the performance of the V-Cone flowmeter in wet gas applications. The geometry of the V-Cone provides a clean measurement of wet gas without liquid build up before or after the meter section. Three V-Cone flowmeters were tested with a beta ratio range from 0.45 to 0.67. The test loop controlled the water loading from 0 to 5% by mass. Each meter was tested at six flowrates under two different pressures. In addition to the performance testing, Southwest also installed a McCrometer supplied ''clear'' V-Cone made with acrylic pipe. This clear meter, under low pressure, allowed a visualization of the flow of wet gas through the meter. Still photography and video cameras were used to capture several combinations of gas flow and water loading. Results show, as expected, that the V-Cone held no water either upstream or downstream of the cone section. Performance tests indicate a slight and consistent positive shift in flow coefficient under increasing water loadings. Smaller beta ratios showed less deviation from baseline conditions than larger beta ratios. (author)

Ifft, S.A.

1997-07-01

388

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

Science.gov (United States)

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.

Gundogdu, Serdar; Sahin, Ozge

2007-01-01

389

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

UK PubMed Central (United Kingdom)

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.

Gundogdu S; Sahin O

2007-01-01

390

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.

Serdar Gundogdu; Ozge Sahin

2007-01-01

391

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)

1985-01-01

392

Fiber optic hot-wire flowmeter based on a metallic coated hybrid long period grating/fiber Bragg grating structure.  

UK PubMed Central (United Kingdom)

In this work an all-optical hot-wire flowmeter based on a silver coated fiber combining a long period grating and a fiber Bragg grating (FBG) structure is proposed. Light from a pump laser at 1480? nm propagating down the fiber is coupled by the long period grating into the fiber cladding and is absorbed by the silver coating deposited on the fiber surface over the Bragg grating structure. This absorption acts like a hot wire raising the fiber temperature locally, which is effectively detected by the FBG resonance shift. The temperature increase depends on the flow speed of the surrounding air, which has the effect of cooling the fiber. It is demonstrated that the Bragg wavelength shift can be related to the flow speed. A flow speed resolution of 0.08? m/s is achieved using this new configuration.

Caldas P; Jorge PA; Rego G; Frazão O; Santos JL; Ferreira LA; Araújo F

2011-06-01

393

Fiber optic hot-wire flowmeter based on a metallic coated hybrid long period grating/fiber Bragg grating structure.  

Science.gov (United States)

In this work an all-optical hot-wire flowmeter based on a silver coated fiber combining a long period grating and a fiber Bragg grating (FBG) structure is proposed. Light from a pump laser at 1480? nm propagating down the fiber is coupled by the long period grating into the fiber cladding and is absorbed by the silver coating deposited on the fiber surface over the Bragg grating structure. This absorption acts like a hot wire raising the fiber temperature locally, which is effectively detected by the FBG resonance shift. The temperature increase depends on the flow speed of the surrounding air, which has the effect of cooling the fiber. It is demonstrated that the Bragg wavelength shift can be related to the flow speed. A flow speed resolution of 0.08? m/s is achieved using this new configuration. PMID:21673779

Caldas, Paulo; Jorge, Pedro A S; Rego, Gaspar; Frazão, Orlando; Santos, José Luís; Ferreira, Luís Alberto; Araújo, Francisco

2011-06-10

394

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 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 m? (more) ?os 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. (more) 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

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

2010-04-01

395

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 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)

2012-01-23

396

API testing program - calibration of microprocessor based flowmeters for integrated metering systems  

Energy Technology Data Exchange (ETDEWEB)

Microprocessor based flowmeter technologies for liquids, such as Coriolis mass meters, and Ultrasonic flowmeters hold great promise. These technologies offer many advantages, such as no rotating parts, self-diagnostic checks, which can help anticipate and warn of impending failures before they have a major impact on the measurement. These meters are substantially different though than other primary devices due to their heavy reliance on the accompanying secondary electronics. One method to prove that they are accurate would be proving the flowmeter, using a pipe prover or small volume prover (SVP), but these proving methods are designed to count 'real time' pulses from a turbine or PD meter between a known volume, they are not designed to count 'time delayed' 'manufactured pulses' from a microprocessor. There are limitations of the manufactured pulse train and it affects the ability of the flowmeter to be proved using current proving technology. The author of this paper, a chairman of an American Petroleum Institute working group, investigated how the 'microprocessor generated pulses' produced by these types of flowmeters, interacted with the existing measurement technologies in use today. Several microprocessor based flowmeter technologies have been tested, including; Ultrasonic, Coriolis, and Helical Turbine with pulse multiplying preamplifier. Wherever possible, flowmeters of various sizes, and from several vendors have been tested. A significant amount of data has been collected which sheds light into why these types of flowmeters are sometimes difficult to prove. This paper describes the API testing program, and the methodology behind it. It presents results and findings, and offers specific recommendations that may eventually be incorporated into API documents and/or standards in the future. (author)

Elliot, Kenneth D. [Omni Flow Computers, Inc., Stafford, TX (United States)

2005-07-01

397

Doppler and range determination for deep space vehicles using active optical transponders.  

UK PubMed Central (United Kingdom)

This paper describes and analyzes two types of laser system employing active transponders that could accurately determine Doppler and range to deep space vehicles from earth-orbiting satellites. The first is a noncoherent optical system in which the Doppler effect on an intensity-modulating subcarrier is measured. The second is a coherent optical system in which the Doppler effect of the optical carrier itself is measured. Doppler and range measurement errors are mathematically modeled and, for three example systems, numerically evaluated.

Kinman PW; Gagliardi RM

1988-11-01

398

Synthesis of the evaluations of electromagnetic flowmeters based on vortex, Coriolis and thermal effects in the framework of SIREP-WIB-EXERA associations.  

Science.gov (United States)

Electronic flowmeters such as electromagnetic flowmeters based on vortex, mass (Coriolis) and thermal effects are being used more and more in industry (water distribution, petrochemicals, food processing). Some of them are used by EDF. A study has been th...

T. Fortin F. Jacq

1997-01-01

399

Kalibrierung einer Miniatur-Permanentmagnet-Potentialsonde zur Geschwindigkeits- und Temperaturmessung in Natrium. (Calibration of a miniature permanent magnet flowmeter probe for velocity and temperature measurement in sodium).  

Science.gov (United States)

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 zer...

J. U. Knebel L. Krebs

1993-01-01

400

The parametric Doppler effect in quartz glass  

Science.gov (United States)

Transformation of frequency is analyzed under the parametric Doppler effect in quartz glass in the "optic collider" scheme. In this scheme, intense laser radiation induces moving inhomogeneities of the refractive index in the glass and the probe radiation undergoes the Doppler frequency shift when being reflected from them. The possibilities of transforming the frequency both within the main transparent region and from the main transparent region to the low- and high-frequency regions separated from the main region by absorption peaks in the infrared and ultraviolet spectral ranges are demonstrated.

Vysotina, N. V.; Rosanov, N. N.; Alekseev, S. G.; Ermolaeva, G. M.; Shilov, V. B.; Malevich, V. L.; Sinitsyn, G. V.

2013-08-01