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Sample records for laser doppler flowmeter

  1. Laser double Doppler flowmeter

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

    2014-05-01

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

  2. Estimation of amputation level with a laser Doppler flowmeter

    Gebuhr, Peter Henrik; Jørgensen, J P; Vollmer-Larsen, B;

    1989-01-01

    Leg amputation levels were decided in 24 patients suffering from atherosclerosis, using the conventional techniques of segmental blood pressure and radioisotope skin clearance. The skin microcirculation was measured and recorded before operation with a laser doppler flowmeter. A high correlation...

  3. Estimation of amputation level with a laser Doppler flowmeter

    Gebuhr, Peter Henrik; Jørgensen, J P; Vollmer-Larsen, B; Nielsen, S L; Alsbjørn, B

    1989-01-01

    Leg amputation levels were decided in 24 patients suffering from atherosclerosis, using the conventional techniques of segmental blood pressure and radioisotope skin clearance. The skin microcirculation was measured and recorded before operation with a laser doppler flowmeter. A high correlation...... was found between the successful amputation levels and the maximal blood perfusion of the skin measured in this way....

  4. A novel, microscope based, non invasive Laser Doppler flowmeter for choroidal blood flow assessment

    Strohmaier, C; Werkmeister, RM; Bogner, B; Runge, C; Schroedl, F; Brandtner, H; Radner, W; Schmetterer, L; Kiel, JW; Grabnerand, G; Reitsamer, HA

    2011-01-01

    Impaired ocular blood flow is involved in the pathogenesis of numerous ocular diseases like glaucoma or AMD. The purpose of the present study was to introduce and validate a novel, microscope based, non invasive laser Doppler flowmeter (NILDF) for measurement of blood flow in the choroid. The custom made NI-LDF was compared with a commercial fiber optic based laser Doppler flowmeter (Perimed PF4000). Linearity and stability of the NI-LDF were assessed in a silastic tubing model (i.d. 0.3 mm) ...

  5. Evaluation of cutaneous blood flow responses by 133Xe washout and a laser-Doppler flowmeter

    A new method for noninvasive measurement of cutaneous blood flow is laser-Doppler flowmetry. The technique is based on the fact that laser light is back-scattered from the moving red blood cells, with Doppler-shifted frequencies; these impulses lead to photodetectors and are converted to flow signals. In this work we used a new system with a low noise level. Comparison was made between this technique and the atraumatic epicutaneous 133Xe technique for measurement of cutaneous blood flow during reactive hyperemia and orthostatic pressure changes. The laser-Doppler flowmeter seems to measure blood flow in capillaries as well as in arteriovenous anastomoses, while the 133Xe method probably measures only capillary flow. A calibration of the laser-Doppler method against the 133Xe method would appear to be impossible in skin areas where arteriovenous anastomoses are present. The changes in blood flow during reactive hyperemia, orthostatic pressure changes, and venous stasis were found to be parallel as measured by the two methods in skin areas without shunt vessels. The laser-Doppler flowmeter would appear to be a useful supplement to the 133Xe washout method in cutaneous vascular physiology, but it is important to keep in mind that different parameters may be measured

  6. ANL Doppler flowmeter

    Karplus, H. B.; Raptis, A. C.; Lee, S.; Simpson, T.

    1985-10-01

    A flowmeter has been developed for measuring flow velocity in hot slurries. The flowmeter works on an ultrasonic Doppler principle in which ultrasound is injected into the flowing fluid through the solid pipe wall. Isolating waveguides separate the hot pipe from conventional ultrasonic transducers. Special clamp-on high-temperature transducers also can be adapted to work well in this application. Typical flows in pilot plants were found to be laminar, giving rise to broad-band Doppler spectra. A special circuit based on a servomechanism sensor was devised to determine the frequency average of such a broad spectrum. The device was tested at different pilot plants. Slurries with particulates greater than 70 microns (0.003 in.) yielded good signals, but slurries with extremely fine particulates were unpredictable. Small bubbles can replace the coarse particles to provide a good signal if there are not too many. Successful operation with very fine particulate slurries may have been enhanced by the presence of microbubbles.

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

    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

  8. Schlieren laser Doppler flowmeter for the human optical nerve head with the flicker stimuli.

    Geiser, Martial H; Truffer, Frederic; Evequoz, Hugo; Khayi, Hafid; Mottet, Benjamin; Chiquet, Christophe

    2013-12-01

    We describe a device to measure blood perfusion for the human optic nerve head (ONH) based on laser Doppler flowmetry (LDF) with a flicker stimuli of the fovea region. This device is self-aligned for LDF measurements and includes near-infrared pupil observation, green illumination, and observation of the ONH. The optical system of the flowmeter is based on a Schlieren arrangement which collects only photons that encounter multiple scattering and are back-scattered out of the illumination point. LDF measurements are based on heterodyne detection of Doppler shifted back-scattered light. We also describe an automated analysis of the LDF signals which rejects artifacts and false signals such as blinks. By using a Doppler simulator consisting of a lens and a rotating diffusing wheel, we demonstrate that velocity and flow vary linearly with the speed of the wheel. A cohort of 12 healthy subjects demonstrated that flicker stimulation induces an increase of 17.8% of blood flow in the ONH. PMID:24296999

  9. Detection of Site-Specific Blood Flow Variation in Humans during Running by a Wearable Laser Doppler Flowmeter

    Wataru Iwasaki

    2015-10-01

    Full Text Available Wearable wireless physiological sensors are helpful for monitoring and maintaining human health. Blood flow contains abundant physiological information but it is hard to measure blood flow during exercise using conventional blood flowmeters because of their size, weight, and use of optic fibers. To resolve these disadvantages, we previously developed a micro integrated laser Doppler blood flowmeter using microelectromechanical systems technology. This micro blood flowmeter is wearable and capable of stable measurement signals even during movement. Therefore, we attempted to measure skin blood flow at the forehead, fingertip, and earlobe of seven young men while running as a pilot experiment to extend the utility of the micro blood flowmeter. We measured blood flow in each subject at velocities of 6, 8, and 10 km/h. We succeeded in obtaining stable measurements of blood flow, with few motion artifacts, using the micro blood flowmeter, and the pulse wave signal and motion artifacts were clearly separated by conducting frequency analysis. Furthermore, the results showed that the extent of the changes in blood flow depended on the intensity of exercise as well as previous work with an ergometer. Thus, we demonstrated the capability of this wearable blood flow sensor for measurement during exercise.

  10. A study for developing an ultrasonic Doppler flowmeter

    Biermans, M.; Bregman, R.

    1984-06-01

    The system parameters for low cost ultrasonic Doppler flowmeters for medical applications were investigated. A flowmeter was built. A phase locked loop is used to find the correct Doppler shift. Laboratory and field tests prove the success of the development, although very often insufficient reflectors exist in the liquids. The accuracy is + or - 5%; the reproducibility is + or - 0.5%.

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

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

    2014-01-01

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

  12. Ultrasonic doppler flowmeter-guided occipital nerve block

    Na, Se Hee; Kim, Tae Wan; Oh, Se-Young; Kweon, Tae Dong; Yoon, Kyung Bong; Yoon, Duck Mi

    2010-01-01

    Background Greater occipital nerve block is used in the treatment of headaches and neuralgia in the occipital area. We evaluated the efficacy of ultrasonic doppler flowmeter-guided occipital nerve block in patients experiencing headache in the occipital region in a randomized, prospective, placebo-controlled study. Methods Twenty-six patients, aged 18 to 70, with headache in the occipital region, were included in the study. Patients received a greater occipital nerve block performed either un...

  13. An electronic Doppler signal generator for assessing continuous-wave ultrasonic Doppler flowmeters

    Smallwood, R. H.; Dixon, P.

    1986-03-01

    The design and performance of the electric Doppler signal generator are described. The features of the CW ultrasonic Doppler flowmeter, which operates in the 2-10 MHz range, that are relevant to the design of the generator are examined. Methods for evaluating the bandwidth, dynamic range, directional separation, and linearity of the zero-crossing detector are discussed. The use of a polyphase network as a phase shifter to generate a single sideband (SSB) signal is analyzed. The SSB generation is performed at a frequency of 100 kHz and the advantages of generation at this frequency are stated. The selection of proper SSB signals for the system is investigated. The performance of the Doppler signal generator is evaluated with a frequency analyzer; sideband rejection ratios and phase error in the quadrature oscillator are calculated. The Doppler generator was applied to a CW flowmeter and output signal levels were measured. The test reveals that the Doppler signal generator's performance exceeds the flowmeter requirements; rejection of the unwanted sideband exceeds 40 dB for Doppler frequencies up to 10 kHz, which is the minimum upper frequency for 10 MHz flowmeters.

  14. Flowmeter

    A flowmeter with a conical rotor is described resting with the cone-shaped shell on a conical wall of the housing for non-flowing medium and lifting from the wall for flowing medium; in addition, it has slots in the cone-shaped shell. By a special shape and retaining slots it is achieved that the rotor exactly follows the changes of the flow velocity. (RW)

  15. Theoretical analysis of the ultrasonic Doppler flowmeter for measurements of high flow velocities

    Tabin, Jozef

    1987-07-01

    A geometric approach is used to analyze the ultrasonic Doppler flowmeter for measurements of flow velocities that are high but yet much smaller than the ultrasound velocity. The approach is based on the calculation of the transit time difference between the ultrasonic waves that are reflected from a moving particle at its various positions. Beam divergence is taken into account, and each path of the ultrasonic wave propagation is approximated by two rectilinear components. It is shown that the Doppler frequency shift is influenced not only by the suspended particle velocity, but also by the mean flow velocity of the fluid. This influence is of second order in the flow velocity.

  16. Quantitative Laser Doppler Flowmetry

    Fredriksson, Ingemar

    2009-01-01

    Laser Doppler flowmetry (LDF) is virtually the only non-invasive technique, except for other laser speckle based techniques, that enables estimation of the microcirculatory blood flow. The technique was introduced into the field of biomedical engineering in the 1970s, and a rapid evolvement followed during the 1980s with fiber based systems and improved signal analysis. The first imaging systems were presented in the beginning of the 1990s. Conventional LDF, although unique in many aspects an...

  17. Laser Doppler imaging, revisited

    Atlan, Michael; Gross, Michel

    2006-01-01

    International audience We present a detection scheme designed to perform laser Doppler imaging in a wide-field configuration, aimed at slow flows characterization. The optical field which carries a spectral information about the local scatterers dynamic state that results from momentum transfer at each scattering event, is analyzed in the temporal frequencies domain. The setup is based on heterodyne off-axis digital holography.

  18. Holographic laser Doppler ophthalmoscopy

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

    2010-01-01

    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.

  19. Laser doppler perfusion imaging

    Waardell, K.

    1992-01-01

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

  20. Laser doppler perfusion imaging

    Waardell, K.

    1992-11-01

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

  1. Laser doppler perfusion imaging

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

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

    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)

  3. Research on ultrasonic Doppler flowmeter simulator%超声多普勒流量模拟器研究

    贾伟; 王小敏

    2011-01-01

    相对传统的流量计,超声多普勒流量计测量适合于多种工况条件和液体类型的流量测量,在工业流量测量中具有广泛的应用前景。为了适应多普勒流量计性能测试和评估的需要,加快流量计的研制进程,本文通过对油田应用环境的分析,提出了基于DDS(直接数字式频率合成)技术的多普勒流量模拟器的设计。完成了硬件、固件程序及计算机软件的开发。应用结果表明,该模拟器的使用能有效地缩短流量计的研发周期,提高工作效率,降低生产成本。%Compared with the traditional flow meters, ultrasonic doppler flowmeter measurement method has more prominent features because it is suitable for various types of working conditions and liquid flow measurement with a wide range of applications. In order to test and evaluate the performance of doppler flowmeter in the development,suitable oilfield application environment of the Doppler flowmeter was proposed based on DDS (direct digital frequency synthesis). Finally, the hardware,firmware and computer software of the Doppler flow simulator are designed. Experiments show that the use of the simulator can effectively reduce the development cycle, improve efficiency and reduce production costs.

  4. Reproducibility and sensitivity of scanning laser Doppler flowmetry during graded changes in PO2

    Strenn, K.; Menapace, R.; Rainer, G.; Findl, O; Wolzt, M.; Schmetterer, L

    1997-01-01

    AIMS/BACKGROUND—Recently a commercially available scanning laser Doppler flowmeter has been produced, which provides two dimensional maps of the retinal perfusion. The aim of the present study was to investigate the reproducibility and the sensitivity of these measurements.
METHODS—16 healthy subjects were randomised to inhale different gas mixtures of oxygen and nitrogen in a double blind crossover study. The following gas mixtures of oxygen and nitrogen were administered: 100% oxygen + 0% n...

  5. Automatic body flexibility classification using laser doppler flowmeter

    Lien, I.-Chan; Li, Yung-Hui; Bau, Jian-Guo

    2015-10-01

    Body flexibility is an important indicator that can measure whether an individual is healthy or not. Traditionally, we need to prepare a protractor and the subject need to perform a pre-defined set of actions. The measurement takes place at the same time when the subject performs required action, which is clumsy and inconvenient. In this paper, we propose a statistical learning model using the technique of random forest. The proposed system can classify body flexibility based on LDF signals analyzed in the frequency domain. The reasons of using random forest are because of their efficiency (fast in classification), interpretable structures and their ability to filter out irrelevant features. In addition, using random forest can prevent the problem of over-fitting, and the output model will become more robust to noises. In our experiment, we use chirp Z-transform (CZT), to transform a LDF signal into its energy values in five frequency bands. Combining the power of the random forest algorithm and frequency band analysis methods, a maximum recognition rate of 66% is achieved. Compared to traditional flexibility measuring process, the proposed system shortens the long and tedious stages of measurement to a simple, fast and pre-defined activity set. The major contributions of our work include (1) a novel body flexibility classification scheme using non-invasive biomedical sensor; (2) a set of designed protocol which is easy to conduct and practice; (3) a high precision classification scheme which combines the power of spectrum analysis and machine learning algorithms.

  6. UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry in the diagnostics of alopecia

    Skomorokha, Diana P.; Pigoreva, Yulia N.; Salmin, Vladimir V.

    2016-04-01

    Development of optical biopsy methods has a great interest for medical diagnostics. In clinical and experimental studies it is very important to analyze blood circulation quickly and accurately, thereby laser Doppler flowmetry (LDF) is widely used. UV laser-induced fluorescence spectroscopy (UV LIFS) is express highly sensitive and widely-spread method with no destructive impact, high excitation selectivity and the possibility to use in highly scattering media. The goal of this work was to assess a correlation of UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry parameters, and a possibility to identify or to differentiate various types of pathological changes in tissues according to their autofluorescence spectra. Three groups of patients with diffuse (symptomatic) alopecia, androgenic alopecia, and focal alopecia have been tested. Each groups consisted of not less than 20 persons. The measurements have been done in the parietal and occipital regions of the sculls. We used the original automated spectrofluorimeter to record autofluorescence spectra, and standard laser Doppler flowmeter BLF-21 (Transonic Systems, Inc., USA) to analyze the basal levels of blood circulation. Our results show that UV LIFS accurately distinguishes the zones with different types of alopecia. We found high correlation of the basal levels of blood circulation and the integrated intensity of autofluorescence in the affected tissue.

  7. Design of Ultrasonic Doppler Flowmeter%超声波多普勒流量计的设计

    涂晓立; 杨道业; 陈静

    2016-01-01

    For the problem that the conventional ultrasonic doppler flowmeter accuracy is low ,the stability is poor ,the dynamic response is slow ,a new type of ultrasonic Doppler flowmeter was developed .Hardware mainly included ultrasonic transducer trans-mitting and receiving circuits ,power amplifier and filter circuit ,mixer circuit,STM32F4 and their peripheral devices .Through adop-ting STM32F4 as the main chip of ultrasonic Doppler flowmeter ,Cortex-M4 core was used in STM32F4 and its hardware FPU unit was built in.DSP instruction set in digital signal processing also increased ,making the capability of digital signal processing was greatly upgraded .The high-precision DDS chip was used in hardware circuit to generate the reference signal ,then the frequency-shifted signal was demodulated 10 kHz using demodulator technology ,which increased the stability of the system measurement and response speed of the flow rate .In the frequency-shifted signal processing ,FFT was adopted to analyze frequency-shifted signal from STM32F4,which improved the measurement accuracy of ultrasonic flow measurement system .Matlab was used to analyze Doppler frequency shift signal spectrum to get its frequency change .%针对传统的超声波多普勒流量计存在的精度低、稳定度差、动态响应慢的问题,研制了一种新型的超声波多普勒流量计。硬件部分主要设计了超声波换能器的发射与接收电路、功率放大与滤波电路、混频电路以及STM32F4及其外围器件。采用STM32F4作为超声波多普勒流量计的主控芯片,STM32F4采用Cortex-M4内核,其内置硬件FPU单元,在数字信号处理方面还增加了DSP指令集,使得它在数字信号处理方面的能力得到大大的提升。在硬件电路中选用高精度的DDS芯片产生基准信号来驱动超声波换能器。在频移信号处理方面,采用中频解调技术将频移信号解调到10 kHz,提高了系统测量的稳定度以及对流速变

  8. Laser Doppler flowmetry in microvascular surgery

    Adrichem, Léon

    1992-01-01

    textabstractIn the first part of this thesis, describing clinical and experimental studies, laser Doppler flowmetry is evaluated as diagnostic tool to assess tissue microcirculation after various microvascular operations. The second part concerns the application of laser Doppler flowmetry to investigate and to objectivate the negative effects of cigarette smoking upon the microcirculation under normal circumstances as well as after microvascular operative procedures. Success of plastic and re...

  9. A 3-D PW ultrasonic Doppler flowmeter: theory and experimental characterization.

    Calzolai, M; Capineri, L; Fort, A; Masotti, L; Rocchi, S; Scabia, M

    1999-01-01

    A complete 3-D ultrasonic pulsed Doppler system has been developed to measure quantitatively the velocity vector field of a fluid flow independently of the probe position. The probe consists of four 2.5 MHz piezocomposite ultrasonic transducers (one central transmitter and three receivers separated by 120 degrees ) to measure the velocity projections along three different directions. The Doppler shift of the three channels is calculated by analog phase and quadrature demodulation, then digitally processed to extract the mean velocity from the complex spectrum. The accuracy of the 3-D Doppler technique has been tested on a moving string phantom providing an error of about 4% for both amplitude and direction with an acquisition window of 100 ms. PMID:18238403

  10. Beam-forming techniques with applications to pulsed Doppler ultrasonic flowmeters

    Fu, C. C.

    The near-field and array approaches to beam forming appear to be the most practical and useful methods for providing uniform illumination of the cross section of blood vessels. Through the near-field approach, the required beam patterns are produced in the near field of pulsed transducers and, as a result, it is most suitable for peripheral applications. Field patterns of pulsed transducers are defined and are investigated by theoretical analysis, numerical simulation, and experimental characterization to verify the validity and indicate the limitations of this approach. Transducers are designed and fabricated, based on these results, and are employed in the preliminary flowmeter system evaluation. The use of transducer arrays is the only viable approach to deepbody measurements and flexible beamwidth adjustment. A theory, founded on the finite Fourier-Bessel and Dini series expansions, is developed to synthesize circularly symmetrical beam patterns by means of concentric annular arrays. Its application to the generation of variable-width uniform beams results in a canonical design procedure. A prototype transducer array suitable for transcutaneous cardiac-output estimation was developed.

  11. 小开河引黄灌区超声波测流应用研究%APPLICATION OF ULTRASONIC WAVE DOPPLER FLOWMETER IN XIAOKAIHE IRRIGATED AREA

    张永云; 王景元; 庞启航; 岳青; 李春健

    2011-01-01

    小开河灌区应用超声波流量计实现了干渠水位、流速、流量、水量在线监测和无线传输.本文依据小开河灌区已建成的H - ADCP测流系统,探讨了H- ADCP的系统结构、系统流程,对流量率定进行了相关分析,建立了关系曲线,并提出了存在的问题.%The ultrasonic wave flowmeter (ADCP) is called the navigation typeflowmeter, installs on the sidewall the flowmeter for the level - likeultrasonic wave Doppler flowmeter (H - ADCP), all uses the ultrasonic measurement water depth, surveys the speed of flow with the Doppler sprinciple, is in the present world a more advanced flow meter. Stillwas the first example in the silt content higher Irrigated Area of Yellow River application, has realized the main channel water level, the speed of flow, the current capacity, the water volume on - line monitor and the wireless transmission. This article rests on Xiaokaihe Irrigated Area of Yellow River H - ADCP which completes automatically to measure flows the system, has outlined the H - ADCP system structure, the system flow the counter - flow quantity rating has carried on the correlation analysis, has established the relation-al curve, and asked the existence question.

  12. Speckles in laser Doppler perfusion imaging

    Rajan, V; Varghese, B.; Leeuwen, van; W. Steenbergen

    2006-01-01

    We report on the quantitative influence of speckles in laser Doppler perfusion imaging. The influence of speckles on the signal amplitude and on the Doppler spectrum is demonstrated experimentally for particle suspensions with different scattering levels and various beam widths. It is shown that the type of tissue affects the instrumental response through the effect of lateral light diffusion on the number of speckles involved in the detection process. These effects are largest for narrow beams.

  13. Analysis of ultrasound propagation in high-temperature nuclear reactor feedwater to investigate a clamp-on ultrasonic pulse doppler flowmeter

    The flow rate of nuclear reactor feedwater is an important factor in the operation of a nuclear power reactor. Venturi nozzles are widely used to measure the flow rate. Other types of flowmeters have been proposed to improve measurement accuracy and permit the flow rate and reactor power to be increased. The ultrasonic pulse Doppler system is expected to be a candidate method because it can measure the flow profile across the pipe cross section, which changes with time. For accurate estimation of the flow velocity, the incidence angle of ultrasound entering the fluid should be estimated using Snell's law. However, evaluation of the ultrasound propagation is not straightforward, especially for a high-temperature pipe with a clamp-on ultrasonic Doppler flowmeter. The ultrasound beam path may differ from what is expected from Snell's law due to the temperature gradient in the wedge and variation in the acoustic impedance between interfaces. Recently, simulation code for ultrasound propagation has come into use in the nuclear field for nondestructive testing. This article analyzes and discusses ultrasound propagation, using 3D-FEM simulation code plus the Kirchhoff method, as it relates to flow profile measurement in nuclear reactor feedwater with the ultrasonic pulse Doppler system. (author)

  14. Laser Doppler measurement of cutaneous blood flow

    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

  15. Fish embryo multimodal imaging by laser Doppler digital holography

    Verrier, Nicolas; Picart, Pascal; Gross, Michel

    2015-01-01

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

  16. Coherent Detection in Laser Doppler Velocimeters

    Hanson, Steen Grüner

    1974-01-01

    The possibility of heterodyning between electromagnetic waves scattered by particles separated in space is explained from a classical point of view and from a quantum mechanical point of view. The last description being carried out using only the Heisenberg uncertainty principle and a rather coarse......, but intelligible particle picture of electromagnetic waves. The analysis is carried out with special emphasis on the heterodyning process in the laser Doppler velocimeter (LDV) because the main purpose of this article is to provide a better understanding of this instrument. An aid for this purpose is...

  17. Ultrasonic Doppler Flowmeter Based on TMS320F28335%基于TMS320F28335的超声多普勒流量计

    水永辉; 刘艳萍; 赵连环; 王庆山

    2012-01-01

    Based on continuous-wave ultrasonic Doppler method,a pipe-flow measurements system,using TMS320F28335 as the cote control chip,was designed to simplify the circuit of current ultrasonic Doppler flowmeter. A detailed block diagram of the system design was given. The feasibility of difference frequency signal demodulation through software was analyzed, and the software design flow chart was presented. The results show that the development can greatly simplify the hardware design, and also has a high dynamic response and accuracy.%针对当前超声波多普勒流量计电路设计复杂的现状,以TMS320F28335作为核心控制芯片,采用连续波超声多普勒测量方法,设计管道流量测量系统.给出详细的系统设计框图,对利用软件实现差频信号的解调的可行性进行了分析,给出软件设计流程图.结果表明;该设计能简化系统硬件设计,同时具有较高的动态响应能力和测量精度.

  18. Widefield laser doppler velocimeter: development and theory.

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

    2007-03-01

    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.

  19. Sub-Doppler laser cooling of potassium atoms

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

    2011-01-01

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

  20. Sub-Doppler laser cooling of potassium atoms

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

    2011-10-15

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

  1. Laser Doppler instrument measures fluid velocity without reference beam

    Bourquin, K. R.; Shigemoto, F. H.

    1971-01-01

    Fluid velocity is measured by focusing laser beam on moving fluid and measuring Doppler shift in frequency which results when radiation is scattered by particles either originally present or deliberately injected into moving fluid.

  2. Muscle activity characterization by laser Doppler Myography

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

    2013-09-01

    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.

  3. Muscle activity characterization by laser Doppler Myography

    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

  4. Evaluating microcirculation by pulsatile laser Doppler signal

    Chao, P. T.; Jan, M. Y.; Hsiu, H.; Hsu, T. L.; Wang, W. K.; Wang, Y. Y. Lin

    2006-02-01

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

  5. Laser Doppler technology applied to atmospheric environmental operating problems

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

    1976-01-01

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

  6. Flowmeters and reciprocity

    Hemp, J.

    1988-11-01

    A general method is given for developing the basic theory of any kind of 'interrogating field' flowmeter. These include electromagnetic flowmeters, transit-time ultrasonic flowmeters, and Coriolis mass flowmeters. The general expression for the weight vector for the Coriolis mass flowmeter is derived and calculated in one configuration.

  7. Design of new seismometer based on laser Doppler effect

    Zhenhui Du(杜振辉); Fuxiang Huang(黄福祥); Chengzhi Jiang(蒋诚志); Zhifei Tao(陶知非); Hua Gao(高华); Lina Lü(吕丽娜)

    2004-01-01

    In order to improve the resolution of seismic acquisition, a new seismic acquisition system based on tangential laser Doppler effect with an optimized differential optical configuration is proposed. The relative movement of the inertia object and the immobile frame is measured by laser Doppler effect, which can avoid the electromagnetic and thermometric interference, and the adoption of frequency-modulated (FM)transmission can improve the ability of anti-jamming. The frequency bandwidth is properly determined by analyzing the frequency of the Doppler signal. The velocity, displacement, acceleration, and frequency to be measured can be real-time acquired by frequency/velocity (F/V) converting the FM Doppler signal.A 100-dB dynamic range and the linear frequency range of 1.0 to 1000 Hz are realized.

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

    Orekhova, Liudmila Yu; Barmasheva, Anna A

    2013-01-01

    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. PMID:23981527

  9. Bone tissue phantoms for optical flowmeters at large interoptode spacing generated by 3D-stereolithography

    Binzoni, Tiziano; Torricelli, Alessandro; Giust, Remo; Sanguinetti, Bruno; Bernhard, Paul; Spinelli, Lorenzo

    2014-01-01

    A bone tissue phantom prototype allowing to test, in general, optical flowmeters at large interoptode spacings, such as laser-Doppler flowmetry or diffuse correlation spectroscopy, has been developed by 3D-stereolithography technique. It has been demonstrated that complex tissue vascular systems of any geometrical shape can be conceived. Absorption coefficient, reduced scattering coefficient and refractive index of the optical phantom have been measured to ensure that the optical parameters r...

  10. Non-intrusive Shock Measurements Using Laser Doppler Vibrometers

    Statham, Shannon M.; Kolaini, Ali R.

    2012-01-01

    Stud mount accelerometers are widely used by the aerospace industry to measure shock environments during hardware qualification. The commonly used contact-based sensors, however, interfere with the shock waves and distort the acquired signature, which is a concern not actively discussed in the community. To alleviate these interference issues, engineers at the Jet Propulsion Laboratory are investigating the use of non-intrusive sensors, specifically Laser Doppler Vibrometers, as alternatives to the stud mounted accelerometers. This paper will describe shock simulation tests completed at the Jet Propulsion Laboratory, compare the measurements from stud mounted accelerometers and Laser Doppler Vibrometers, and discuss the advantages and disadvantages of introducing Laser Doppler Vibrometers as alternative sensors for measuring shock environments.

  11. Fano-Doppler laser cooling of hybrid nanostructures.

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

    2011-09-27

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

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

    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

  13. Multi-beam Laser Doppler Vibrometer with fiber sensing head

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

    2012-06-01

    Laser Doppler vibrometry (LDV) is a well known technique to measure the motions, vibrations and mode shapes of structures and machine components. Photodetector-based LDV can only offer a point-wise measurement. However, it is possible to scan the laser beam to build up a vibrometric image. These scanning laser Doppler vibrometers (SLDV) assume that the measurement conditions remain invariant while multiple and identical, sequential measurements are performed. This assumption makes SLDVs impractical to do measurement on transient events. In this paper, we introduce a new method of generating multiple laser beams with different frequency shifts. The laser beams are projected on different points, and the reflected beams interfere with a common reference beam. The cross-talk among object beams can be bypassed with a proper selection of frequency shifts. A simultaneous vibration measurement on multiple points is realized using a single photodetector. Based on the proposed spatial-encoding technology, a self-synchronized prototype of fiber-based multipoint laser Doppler vibrometer at 1550nm wavelength is developed. An addition red pilot laser is used for aiming purpose. It has the flexibility to measure the vibration of different points on various surfaces. The prototype is used to measure the vibration of different points on a cantilever beam and a plate. The measured results match well with simulation results using finite element method (FEM).

  14. Holographic laser Doppler imaging of microvascular blood flow

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

    2014-01-01

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

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

    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

  16. Anomaly Detection In Additively Manufactured Parts Using Laser Doppler Vibrometery

    Hernandez, Carlos A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-29

    Additively manufactured parts are susceptible to non-uniform structure caused by the unique manufacturing process. This can lead to structural weakness or catastrophic failure. Using laser Doppler vibrometry and frequency response analysis, non-contact detection of anomalies in additively manufactured parts may be possible. Preliminary tests show promise for small scale detection, but more future work is necessary.

  17. Processor operated correlator with applications to laser Doppler signals

    Bisgaard, C.; Johnsen, B.; Hassager, Ole

    1984-01-01

    A 64-channel correlator is designed with application to the processing of laser Doppler anemometry signals in the range 200 Hz to 250 kHz. The correlator is processor operated to enable the consecutive sampling of 448 correlation functions at a rate up to 500 Hz. Software is described to identify a...

  18. Laser Doppler velocimetry in Microchannels using integrated optical waveguides.

    Pandraud, G.; Berg, van den A.; Semenov, S.N.

    2000-01-01

    The possibility of laser Doppler velocimetry (LDV) in microchannels, where particles are suspended in a liquid, and where oscillating or evanescent guided coherent light wave is present, is examined theoretically. The conditions for the observation of the transverse and longitudinal collective phore

  19. Coherent Doppler Laser Radar: Technology Development and Applications

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

    2000-01-01

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

  20. Modern ultrasonic flowmeters

    Gurevich, V. M.; Truman, S. G.

    1986-01-01

    The current status of ultrasonic flowmeters were reviewed on the basis of materials published in the Soviet Union and elsewhere. The following advantages of ultrasonic flowmeters over earlier instruments are cited. A comparative analysis is made of the design methods employed in ultrasonic flowmeters. The evolution of ultrasonic flowmetering is traced from the first generation and trends in their development are analyzed.

  1. Scanning laser doppler velocimeter using iodine iodine-vapor discriminator

    This paper presents a scanning laser doppler velocimeter (SLDV) that is able to measure the velocity over two dimensions. SDV can be used to measure the 2-D velocity of a rotating disk or fluid by using the molecular iodine absorption line (1109) as the frequency discrimination to determine the doppler shift of the target backscattering. The laser source, a narrow line-width Nd:YAG laser at the second harmonic, is frequency locked to the 1109 line as the frequency reference by a digital PID servo with the frequency jitter less than 1 MHz for arbitrarily long periods. Experimental results show that SDV is capable of mapping the speed vector of the target, and the measurement uncertainty of the rotating disk speed is less than 0.25 m/s.

  2. Three-dimensional laser cooling at the Doppler limit

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

    2014-01-01

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

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

    Rodrigo, Peter John; Pedersen, Christian

    2014-01-01

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

  4. Catadioptric Optics for laser Doppler velocimeter applications

    Dunagan, Stephen E.

    1989-01-01

    In the design of a laser velocimeter system, attention must be given to the performance of the optical elements in their two principal tasks: focusing laser radiation into the probe volume, and collecting the scattered light. For large aperture applications, custom lens design and fabrication costs, long optical path requirements, and chromatic aberration (for two color operation) can be problematic. The adaptation of low cost Schmidt-Cassegrain astronomical telescopes to perform these laser beam manipulation and scattered light collection tasks is examined. A generic telescope design is analyzed using ray tracing and Gaussian beam propagation theory, and a simple modification procedure for converting from infinite to near unity conjugate ratio operation with image quality near the diffraction limit was identified. Modification requirements and performance are predicted for a range of geometries. Finally, a 200-mm-aperture telescope was modified for f/10 operation; performance data for this modified optic for both laser beam focusing and scattered light collection tasks agree well with predictions.

  5. Laser Doppler imaging for intraoperative human brain mapping

    Raabe, A; Van De Ville, D.; Leutenegger, M.; Szelényi, A; Hattingen, E; R. Gerlach; Seifert, V.; Hauger, C.; Lopez, A; Leitgeb, R.; Unser, M.; Martin-Williams, E.J.; Lasser, T.

    2009-01-01

    The identification and accurate location of centers of brain activity are vital both in neuro-surgery and brain research. This study aimed to provide a non-invasive, non-contact, accurate, rapid and user-friendly means of producing functional images intraoperatively. To this end a full field Laser Doppler imager was developed and integrated within the surgical microscope and perfusion images of the cortical surface were acquired during awake surgery whilst the patient performed a predet...

  6. Velocity Measurement Based on Laser Doppler Effect

    ZHANG Yan-Yan; HUO Yu-Jing; HE Shu-Fang; GONG Ke

    2010-01-01

    @@ A novel method for velocity measurement is presented.In this scheme,a parallel-linear-polarization dualfrequency laser is incident on the target and senses the target velocity with both the frequencies,which can increase the maximum measurable velocity significantly.The theoretical analysis and verification experiment of the novel method are presented,which show that high-velocity measurement can be achieved with high precision using this method.

  7. Velocity Measurement Based on Laser Doppler Effect

    A novel method for velocity measurement is presented. In this scheme, a parallel-linear-polarization dual-frequency laser is incident on the target and senses the target velocity with both the frequencies, which can increase the maximum measurable velocity significantly. The theoretical analysis and verification experiment of the novel method are presented, which show that high-velocity measurement can be achieved with high precision using this method. (fundamental areas of phenomenology(including applications))

  8. Integrated optoelectronic probe including a vertical cavity surface emitting laser for laser Doppler perfusion monitoring

    Serov, Alexander N.; Nieland, Janharm; Oosterbaan, Sjoerd; Mul, de Frits F.M.; Kranenburg, van Herma; Bekman, Herman H.P.Th.; Steenbergen, Wiendelt

    2006-01-01

    An integrated optoelectronic probe with small dimensions, for direct-contact laser Doppler blood flow monitoring has been realized. A vertical cavity surface emitting laser (VCSEL), and a chip with photodetectors and all necessary electronics are integrated in a miniature probe head connected to a l

  9. Integrated Optoelectronic Probe Including a Vertical Cavity Surface Emitting Laser for Laser Doppler Perfusion Monitoring

    Serov, A.N.; Nieland, J.; Oosterbaan, S.; Steenbergen, W.; Bekman, H.H.P.T.; Mul, F.F.M. de; Kranenburg, H. van

    2006-01-01

    An integrated optoelectronic probe with small dimensions, for direct-contact laser Doppler blood flow monitoring has been realized. A vertical cavity surface emitting laser (VCSEL), and a chip with photodetectors and all necessary electronics are integrated in a miniature probe head connected to a l

  10. Mucosal blood flow measurements using laser Doppler perfusion monitoring

    Dag Arne Lihaug Hoff; Hans Gregersen; Jan Gunnar Hatlebakk

    2009-01-01

    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.

  11. Holographic laser Doppler imaging of pulsatile blood flow

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

    2015-01-01

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

  12. Fiber optic laser Doppler anemometry in swirling jets

    Taghavi, R.; Rice, E. J.

    1991-01-01

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

  13. Sub-Doppler laser cooling and magnetic trapping of erbium

    Berglund, Andrew J; McClelland, Jabez J

    2008-01-01

    We investigate cooling mechanisms in magneto-optically and magnetically trapped erbium. We find efficient sub-Doppler cooling in our trap, which can persist even in large magnetic fields due to the near degeneracy of two Lande g factors. Furthermore, a continuously loaded magnetic trap is demonstrated where we observe temperatures below 25 microkelvin. These favorable cooling and trapping properties suggest a number of scientific possibilities for rare-earth atomic physics, including narrow linewidth laser cooling and spectroscopy, unique collision studies, and degenerate bosonic and fermionic gases with long-range magnetic dipole coupling.

  14. Laser spectroscopy of multi-level doppler broadened atomic system

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

  15. Novel measure for the calibration of laser Doppler flowmetry devices

    Dunaev, Andrey V.; Zherebtsov, Evgeny A.; Rogatkin, Dmitrii A.; Stewart, Neil A.; Sokolovski, Sergei G.; Rafailov, Edik U.

    2014-03-01

    The metrological basis for optical non-invasive diagnostic devices is an unresolved issue. A major challenge for laser Doppler flowmetry (LDF) is the need to compare the outputs from individual devices and various manufacturers to identify variations useful in clinical diagnostics. The most common methods for instrument calibration are simulants or phantoms composed of colloids of light-scattering particles which simulate the motion of red blood cells based on Brownian motion. However, such systems have limited accuracy or stability and cannot calibrate for the known rhythmic components of perfusion (0.0095-1.6 Hz). To solve this problem, we propose the design of a novel technique based on the simulation of moving particles using an electromechanical transducer, in which a precision piezoelectric actuator is used (e.g., P-602.8SL with maximum movement less than 1 mm). In this system, Doppler shift is generated in the layered structure of different solid materials with different optical light diffusing properties. This comprises a fixed, light transparent upper plane-parallel plate and an oscillating fluoroplastic (PTFE) disk. Preliminary studies on this experimental setup using the LDF-channel of a "LAKK-M" system demonstrated the detection of the linear portion (0-10 Hz with a maximum signal corresponding to Doppler shift of about 20 kHz) of the LDF-signal from the oscillating frequency of the moving layer. The results suggest the possibility of applying this technique for the calibration of LDF devices.

  16. Evaluation of a combined reflectance photoplethysmography and laser Doppler flowmetry surface probe

    Z Abdollahi; Phillips, J. P.; Kyriacou, P. A.

    2013-01-01

    This study presents evaluation of a system combining laser Doppler flowmetry and photoplethysmography (PPG) in a single probe for the simultaneous measurement of perfusion and blood flow in the finger. A cuff sphygmomanometer was used to partially occlude the arteries supplying the hand to investigate the effect of low pressure on photoplethysmographic and laser Doppler signals and also on calculated arterial blood oxygen saturation values (SpO2). Red and infrared PPG and Doppler signals were...

  17. Magnetostriction measurement in thin films using laser Doppler vibrometry

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

  18. Evaluation of gingival vascularisation using laser Doppler flowmetry

    Vitez, B.; Todea, C.; Velescu, A.; Şipoş, C.

    2016-03-01

    Aim: The present study aims to assess the level of vascularisation of the lower frontal gingiva of smoker patients, in comparison with non-smokers by using Laser Doppler Flowmetry (LDF), in order to determine the changes in gingival microcirculation. Material & methods: 16 volunteers were included in this study and separated into 2 equal groups: non-smoker subjects in Group I and smoker subjects in Group II. All patients were submitted to a visual examination and professional cleaning The gingival bloodflow of each patient was recorded in 5 zones using LDF, resulting in a total of 80 recordings. LDF was done with the Moor Instruments Ltd. "moorLAB" Laser Doppler. All data were collected as graphs, raw values and statistically analyzed. Results: After strict analysis results show that Group II presents a steady level of gingival microcirculation with even patterns in the graph, while Group I shows many signs of damage to it`s microvascular system through many irregularities in the microcirculation level and graph patterns. Conclusion: The results suggest that prolonged smoking has a definitive effect on the gingival vascularisation making it a key factor in periodontal pathology.

  19. Measuring with laser Doppler vibrometer on moving frame (LDVMF)

    Rahimi, Siamand; Li, Zili; Dollevoet, Rolf

    2014-05-01

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

  20. Application of Laser Doppler Vibrometery for human heart auscultation.

    Koegelenberg, S; Scheffer, C; Blanckenberg, M M; Doubell, A F

    2014-01-01

    In this study the potential of a Laser Doppler Vibrometer (LDV) was tested as a non-contact sensor for the classification of heart sounds. Of the twenty participants recorded using the LDV, five presented with Aortic Stenosis (AS), three were healthy and twelve presented with other pathologies. The recorded heart sounds were denoised and segmented using a combination of the Electrocardiogram (ECG) data and the complexity of the signal. Frequency domain features were extracted from the segmented heart sound cycles and used to train a K-nearest neighbor classifier. Due to the small number of participants, the classifier could not be trained to differentiate between normal and abnormal participants, but could successfully distinguish between participants who presented with AS and those who did not. A sensitivity of 80 % and a specificity of 100 % were achieved a test dataset. PMID:25570986

  1. Laser Doppler vibrometry measurement of the mechanical myogram

    Rohrbaugh, John W.; Sirevaag, Erik J.; Richter, Edward J.

    2013-12-01

    Contracting muscles show complex dimensional changes that include lateral expansion. Because this expansion process is intrinsically vibrational, driven by repetitive actions of multiple motor units, it can be sensed and quantified using the method of Laser Doppler Vibrometry (LDV). LDV has a number of advantages over more traditional mechanical methods based on microphones and accelerometers. The LDV mechanical myogram from a small hand muscle (the first dorsal interosseous) was studied under conditions of elastic loading applied to the tip of the abducted index finger. The LDV signal was shown to be related systematically to the level of force production, and to compare favorably with conventional methods for sensing the mechanical and electrical aspects of muscle contraction.

  2. Dead time effects in laser Doppler anemometry measurements

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

    2014-01-01

    We present velocity power spectra computed by the so-called direct method from burst-type laser Doppler anemometer (LDA) data, both measured in a turbulent round jet and generated in a computer. Using today’s powerful computers, we have been able to study more properties of the computed spectra...... frequency range, starting around the cutoff frequency due to the finite size of the MV. Using computer-generated data mimicking the LDA data, these effects have previously been shown to appear due to the effect of dead time, i.e., the finite time during which the system is not able to acquire new...... measurements. These dead times can be traced back to the fact that the burst-mode LDA cannot measure more than one signal burst at a time. Since the dead time is approximately equal to the residence time for a particle traversing a measurement volume, we are dealing with widely varying dead times, which...

  3. Laser frequency stabilization using a dispersive line shape induced by Doppler Effect.

    Wang, Qing; Qi, Xianghui; Liu, Shuyong; Yu, Jiachen; Chen, Xuzong

    2015-02-01

    We report a simple and robust Doppler-free spectroscopic technique to stabilize a laser frequency to the atomic transition. By employing Doppler Effect on the atomic beam, we obtained a very stable dispersive signal with a high signal-to-noise ratio and no Doppler-background, which served as an error signal to electronically stabilize a laser frequency without modulation. For validating the performance of this technique, we locked a DFB laser to the (133)Cs D2 line and observed an efficient suppression of the frequency noise and a long-term reduction of the frequency drifts in a laboratory environment. PMID:25836158

  4. Novel Applications of Laser Doppler Vibration Measurements to Medical Imaging

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

    2013-06-01

    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.

  5. Laser Doppler flowmetry evaluation of gingival recovery response after laser treatment

    Todea, Carmen; Cânjǎu, Silvana; Dodenciu, Dorin; Miron, Mariana I.; Tudor, Anca; Bǎlǎbuc, Cosmin

    2013-06-01

    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.

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

    Ristić Slavica S.

    2012-01-01

    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

  7. Carotid blood flow measured by an ultrasonic volume flowmeter in carotid stenosis and patients with dementia.

    UEMATSU, S.; Folstein, M F

    1985-01-01

    The volume flowmeter is a simple, noninvasive Doppler ultrasound technique that provides accurate measurement of carotid artery diameter and flow. The device provides a useful laboratory test that can aid significantly in diagnosis of carotid stenosis and dementia.

  8. Laser Doppler imaging for intraoperative human brain mapping.

    Raabe, A; Van De Ville, D; Leutenegger, M; Szelényi, A; Hattingen, E; Gerlach, R; Seifert, V; Hauger, C; Lopez, A; Leitgeb, R; Unser, M; Martin-Williams, E J; Lasser, T

    2009-02-15

    The identification and accurate location of centers of brain activity are vital both in neuro-surgery and brain research. This study aimed to provide a non-invasive, non-contact, accurate, rapid and user-friendly means of producing functional images intraoperatively. To this end a full field Laser Doppler imager was developed and integrated within the surgical microscope and perfusion images of the cortical surface were acquired during awake surgery whilst the patient performed a predetermined task. The regions of brain activity showed a clear signal (10-20% with respect to the baseline) related to the stimulation protocol which lead to intraoperative functional brain maps of strong statistical significance and which correlate well with the preoperative fMRI and intraoperative cortical electro-stimulation. These initial results achieved with a prototype device and wavelet based regressor analysis (the hemodynamic response function being derived from MRI applications) demonstrate the feasibility of LDI as an appropriate technique for intraoperative functional brain imaging. PMID:19049824

  9. Laser Doppler flowmetry: reproducibility, reliability, and diurnal blood flow variations.

    Roeykens, Herman J J; Deschepper, Ellen; De Moor, Roeland J G

    2016-08-01

    The aim of this investigation was (1) to evaluate the reliability of laser Doppler flowmetry (LDF) taking into consideration the use of a silicone splint and the inclination of the probe towards the buccal surface of a human tooth and (2) to determine whether diurnal variations of pulpal blood flow can be registered by means of LDF. Forty-one splints were made by one and the same principal investigator for the registration of pulpal blood flow in vivo in a maxillary right central incisor. Thirty dentists, without experience in LDF recording, were then asked to drill a right-angled shaft in a pre-manufactured splint with a referral point at 2 mm from the enamel-cement border central on the buccal surface of the right central upper incisor. The remaining 11 splints were handled by the principal investigator. The shafts in the 30 splints were analysed using Cone Beam CT imaging of the axial and sagittal angles and compared these to the 11 shafts prepared by the trained principal investigator. LDF was recorded for 90 s in each splint and statistically analysed. LDF values without the use of a splint were statistically significantly different (p < 0.05) and the variance was greater, indicating the superiority of splint use. Significant diurnal variations on LDF values were observed, indicating that special attention should be paid to registration during the day, especially when multiple measurements are to be compared. PMID:27184153

  10. Arterial compliance measurement using a noninvasive laser Doppler measurement system

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

    2000-11-01

    The aim of this study was to study the elasticity of the arterial wall using a non-invasive laser Doppler measurement system. The elasticity of the arterial wall is described by its compliance factor, which can be determined when both blood pressure and the radial velocity of the arterial wall are known. To measure radical velocity we used a self- mixing interferometer. The compliance factors were measured from six healthy volunteers, whose ages were varied from 21 to 32. Although a single volunteer's compliance factor is presented as an example, this paper treated the volunteers as a group. First, the elastic modulus, which is inversely proportional to the compliance factor, was determined. Then, an exponential curve was fitted into the measured data and a characteristic equation for the elastic modulus of the arterial wall was determined. The elastic modulus was calculated at different pressures and the results were compared to the static incremental modulus of a dog's femoral artery. The results indicate that there is a correlation between human elastic and canine static incremental modulus for blood pressures varying from 60 to 110 mmHg.

  11. Cardiorespiratory interactions: Noncontact assessment using laser Doppler vibrometry.

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

    2016-06-01

    The application of a noncontact physiological recording technique, based on the method of laser Doppler vibrometry (LDV), is described. The effectiveness of the LDV method as a physiological recording modality lies in the ability to detect very small movements of the skin, associated with internal mechanophysiological activities. The method is validated for a range of cardiovascular variables, extracted from the contour of the carotid pulse waveform as a function of phase of the respiration cycle. Data were obtained from 32 young healthy participants, while resting and breathing spontaneously. Individual beats were assigned to four segments, corresponding with inspiration and expiration peaks and transitional periods. Measures relating to cardiac and vascular dynamics are shown to agree with the pattern of effects seen in the substantial body of literature based on human and animal experiments, and with selected signals recorded simultaneously with conventional sensors. These effects include changes in heart rate, systolic time intervals, and stroke volume. There was also some evidence for vascular adjustments over the respiration cycle. The effectiveness of custom algorithmic approaches for extracting the key signal features was confirmed. The advantages of the LDV method are discussed in terms of the metrological properties and utility in psychophysiological research. Although used here within a suite of conventional sensors and electrodes, the LDV method can be used on a stand-alone, noncontact basis, with no requirement for skin preparation, and can be used in harsh environments including the MR scanner. PMID:26970208

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

    Eduardo, Flavia Tavares de Oliveira de Paula

    2004-07-01

    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)

  13. Low resource processing algorithms for laser Doppler blood flow imaging.

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

    2011-07-01

    The emergence of full field laser Doppler blood flow imaging systems based on CMOS camera technology means that a large amount of data from each pixel in the image needs to be processed rapidly and system resources need to be used efficiently. Conventional processing algorithms that are utilized in single point or scanning systems are therefore not an ideal solution as they will consume too much system resource. Two processing algorithms that address this problem are described and efficiently implemented in a field programmable gate array. The algorithms are simple enough to use low system resource but effective enough to produce accurate flow measurements. This enables the processing unit to be integrated entirely in an embedded system, such as in an application-specific integrated circuit. The first algorithm uses a short Fourier transformation length (typically 8) but averages the output multiple times (typically 128). The second method utilizes an infinite impulse response filter with a low number of filter coefficients that operates in the time domain and has a frequency-weighted response. The algorithms compare favorably with the reference standard 1024 point fast Fourier transform in terms of both resource usage and accuracy. The number of data words per pixel that need to be stored for the algorithms is 1024 for the reference standard, 8 for the short length Fourier transform algorithm and 5 for the algorithm based on the infinite impulse response filter. Compared to the reference standard the error in the flow calculation is 1.3% for the short length Fourier transform algorithm and 0.7% for the algorithm based on the infinite impulse response filter. PMID:21316289

  14. Doppler shift of a laser pulse beam scattered by a rotating cone and cylinder

    Based on laser radar equations, a Doppler shift model of a laser pulse beam scattered by a rotating arbitrary convex target is reported in this paper. The boundary relations between an incident pulse beam and the detected area elements are analyzed by geometric methods. The Doppler shift characteristics of the rotating cone and cylinder are discussed and the difference between the laser pulse beam and the plane wave scattered from the same rotating target is compared accordingly. Numerical simulations show that the Doppler shift is tightly relevant to their dimensions, speeds, and so on. In the same incidence conditions, the pulse beam and plane wave have difference peak values and the same Doppler shift bandwidth. If the waist radius of the pulse beam is larger, the peak value is higher, and the Doppler shifts are proportional to the speed of the rotating target. By virtue of our theoretical model, we probe into the scattered characteristics of the Doppler shifts of a laser pulse beam, which would benefit target identification in national defense. (general)

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

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

    1997-09-01

    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.

  16. LASER-DOPPLER VELOCIMETRY AND MONTE-CARLO SIMULATIONS ON MODELS FOR BLOOD PERFUSION IN TISSUE

    DEMUL, FFM; KOELINK, MH; KOK, ML; HARMSMA, PJ; GREVE, J; GRAAFF, R; AARNOUDSE, JG

    1995-01-01

    Laser Doppler flow measurements and Monte Carlo simulations on small blood perfusion flow models at 780 nm are presented and compared. The dimensions of the optical sample volume are investigated as functions of the distance of the laser to the detector and as functions of the angle of penetration o

  17. Electromagnetic flowmeter for dielectric liquids.

    Amare, T.

    1995-01-01

    Experimental investigation and theoretical analysis of an electromagnetic flowmeter designed for use with dielectric liquids has been carried out. An extensive survey of the industrial users of flowmeters has been made, involving the participation of over 47 companies, which provides information about the current industrial use, attitudes and attributes of electromagnetic and other types of flowmeters. The design of the flowmeter is mainly concerned with overcoming the charge n...

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

    Verrier, Nicolas; Gross, Michel

    2014-01-01

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

  19. Comparison of laser Doppler and laser speckle contrast imaging using a concurrent processing system

    Sun, Shen; Hayes-Gill, Barrie R.; He, Diwei; Zhu, Yiqun; Huynh, Nam T.; Morgan, Stephen P.

    2016-08-01

    Full field laser Doppler imaging (LDI) and single exposure laser speckle contrast imaging (LSCI) are directly compared using a novel instrument which can concurrently image blood flow using both LDI and LSCI signal processing. Incorporating a commercial CMOS camera chip and a field programmable gate array (FPGA) the flow images of LDI and the contrast maps of LSCI are simultaneously processed by utilizing the same detected optical signals. The comparison was carried out by imaging a rotating diffuser. LDI has a linear response to the velocity. In contrast, LSCI is exposure time dependent and does not provide a linear response in the presence of static speckle. It is also demonstrated that the relationship between LDI and LSCI can be related through a power law which depends on the exposure time of LSCI.

  20. A detection method of laser doppler signal based on topo-logical contravariance

    ZHANG Yu-cun; LIU Hai-bin

    2009-01-01

    To detect the laser doppler signal, the unknown signal is tracked by the known signal using the concept of topological contravarisnce. The unknown topological space U and known space Mare founded, and then the unknown signal's trans-formation is tracked dynamically according to this mapping relationship between the two spaces. The system equation is obtained by gradient-descent method, and the conditions of stability are given by Poincare mapping. The proposed method is applied to measure the in-plane displacement signal of the solid 50 m away using laser doppler, signal The result proves that the method can detect laser doppler, signal accurately, its relative error is less than 0.7%.

  1. Measurement of two-component flow using ultrasonic flowmeters

    Whitehouse, J. C.; Eghbali, D. A.; Flitton, V. E.; Anderson, D. G.

    Calibration of transit-time and Doppler ultrasonic flowmeters under two-component flow conditions has been conducted on 400 mm (16-in.) pipe. Testing covered total flows of 0.19 to 1.89 m(exp 3)/s (3000 to 30,000 gpm) and void fractions up to 40 percent. Both flowmeter types accurately measured total volumetric flow over a portion of their ranges. Pipe average void fraction, based on a three-beam gamma densitometer, was used to determine water component flow under stratified flow conditions, with similar results.

  2. Accuracy of flowmeters measuring horizontal groundwater flow in an unconsolidated aquifer simulator.

    Bayless, E.R.; Mandell, Wayne A.; Ursic, James R.

    2011-01-01

    Borehole flowmeters that measure horizontal flow velocity and direction of groundwater flow are being increasingly applied to a wide variety of environmental problems. This study was carried out to evaluate the measurement accuracy of several types of flowmeters in an unconsolidated aquifer simulator. Flowmeter response to hydraulic gradient, aquifer properties, and well-screen construction was measured during 2003 and 2005 at the U.S. Geological Survey Hydrologic Instrumentation Facility in Bay St. Louis, Mississippi. The flowmeters tested included a commercially available heat-pulse flowmeter, an acoustic Doppler flowmeter, a scanning colloidal borescope flowmeter, and a fluid-conductivity logging system. Results of the study indicated that at least one flowmeter was capable of measuring borehole flow velocity and direction in most simulated conditions. The mean error in direction measurements ranged from 15.1 degrees to 23.5 degrees and the directional accuracy of all tested flowmeters improved with increasing hydraulic gradient. The range of Darcy velocities examined in this study ranged 4.3 to 155 ft/d. For many plots comparing the simulated and measured Darcy velocity, the squared correlation coefficient (r2) exceeded 0.92. The accuracy of velocity measurements varied with well construction and velocity magnitude. The use of horizontal flowmeters in environmental studies appears promising but applications may require more than one type of flowmeter to span the range of conditions encountered in the field. Interpreting flowmeter data from field settings may be complicated by geologic heterogeneity, preferential flow, vertical flow, constricted screen openings, and nonoptimal screen orientation.

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

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

    2012-01-01

    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.

  4. A Reference Optical System of Laser Doppler Longitudinal Displacement Measurement

    张存满; 赵洋; 李达成

    2001-01-01

    In this paper, a new reference optical system is put forward to achieve longitudinal displacement measurement. An optical grating is used for frequency mixing and getting high SNR signals in the measurement. Conditions and methods for getting Doppler beat signals are presented.The experiments indicate that this optical syetem can be used to measure the longitudinal displacement with high accuracy.

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

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

    2010-01-01

    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.}

  6. Doppler-free spectroscopy on Cs D$_1$ line with a dual-frequency laser

    Hafiz, Moustafa Abdel; De Clercq, Emeric; Boudot, Rodolphe

    2016-01-01

    We report on Doppler-free laser spectroscopy in a Cs vapor cell using a dual-frequency laser system tuned on the Cs D$_1$ line. Using counter-propagating beams with crossed linear polarizations, an original sign-reversal of the usual saturated absorption dip and large increase in Doppler-free atomic absorption is observed. This phenomenon is explained by coherent population trapping (CPT) effects. The impact of laser intensity and light polarization on absorption profiles is reported in both single-frequency and dual-frequency regimes. In the latter, frequency stabilization of two diode lasers was performed, yielding a beat-note fractional frequency stability at the level of $3 \\times 10^{-12}$ at 1 s averaging time. These performances are about an order of magnitude better than those obtained using a conventional single-frequency saturated absorption scheme.

  7. He-Ne laser effects on blood microcirculation. An in vivo study through laser doppler flowmetry

    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 (λ=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/cm2 dose was utilized, with an intensity of 6 mW/cm2. 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)

  8. Laser Doppler flowmetry is valid for measurement of cerebral blood flow autoregulation lower limit in rats

    Tonnesen, Jan; Pryds, Anders; Larsen, Erik Hviid;

    2005-01-01

    Laser Doppler flowmetry (LDF) is a recent technique that is increasingly being used to monitor relative changes in cerebral blood flow whereas the intra-arterial 133xenon injection technique is a well-established method for repeated absolute measurements of cerebral blood flow. The aim of this st......Laser Doppler flowmetry (LDF) is a recent technique that is increasingly being used to monitor relative changes in cerebral blood flow whereas the intra-arterial 133xenon injection technique is a well-established method for repeated absolute measurements of cerebral blood flow. The aim...... in similar results. We conclude that even though LDF overestimated CBF during haemorrhagic shock caused by controlled haemorrhage, the lower limit autoregulation was correctly identified. The laser Doppler technique provides a reliable method for detection of a wide range of cerebral blood flow changes under...... CO2 challenge. Haemodilution influences the two methods differently causing relative overestimation of blood flow by the laser Doppler technique compared to the 133xenon method....

  9. The e-Beam Sustained Laser Technology for Space-based Doppler Wind Lidar

    Brown, M. J.; Holman, W.; Robinson, R. J.; Schwarzenberger, P. M.; Smith, I. M.; Wallace, S.; Harris, M. R.; Willetts, D. V.; Kurzius, S. C.

    1992-01-01

    An overview is presented of GEC Avionics activities relating to the Spaceborne Doppler Wind Lidar. In particular, the results of design studies into the use of an e-beam sustained CO2 laser for spaceborne applications, and experimental work on a test bed system are discussed.

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

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

    2002-01-01

    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...

  11. Laser Doppler measurements of turbulent parameters in different multiple-propeller systems

    Baudou, C.; Xuereb, C.; Costes, J.; Bertrand, J. [Centre National de la Recherche Scientifique, 31 - Toulouse (France). Inst. du Genie Chimique

    2000-03-01

    Using laser Doppler anemometry measurements in the r-y plane, two different vessels equipped with two downward pumping propeller were studied. In the turbulent flow, the integral flow, the integral scales, the Taylor microscales, and the Kolmogorov microscale were determined. The authors' comparison with the literature shows that this combination of propellers produces larger eddies than a Rushton turbine. (orig.)

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

    Broučková, Zuzana; Vít, T.; Trávníček, Zdeněk

    Paris: E D P SCIENCES, 2015 - (Vít, T.; Dančová, P.), s. 71-77. (EPJ Web of Conferences. 92). ISSN 2100-014X. [Experimental Fluid Mechanics 2014. Český Krumlov (CZ), 18.11.2014-21.11.2014] R&D Projects: GA ČR GA14-08888S Institutional support: RVO:61388998 Keywords : synthetic jet * laser Doppler vibrometry * laser induced fluorescence Subject RIV: BJ - Thermodynamics

  13. Ultrasonic flowmetering with reflected pulses

    Hoyle, D. C.; Glicksman, L. R.; Peterson, C. R.

    1984-09-01

    Consolidated Edison of New York City has expressed the need for a new gasmeter for accurately monitoring large diameter interdistrict gas transmission lines for loss due to theft or leakage. A research effort aimed at developing a new flowmeter for Con Edison is described. The new flowmeter uses ultrasonic flowmetering technology in a novel way to meet Con Edison's four major design specifications: the flowmeter should be accurate to 0.5 percent of totalized flow over one year, it should be much simpler to install than a conventional flowmeter, essentially meaning that excavation be limited to that necessary to expose the upper surface of a buried main; its installation must not require service shutdown; and, the flowmeter should not require zero-flow calibration once installed in the gas main.

  14. Laser Doppler microscopy of blood flows in fish embryos at different stages of ontogenesis

    Savchenko, Natalia B.; Priezzhev, Alexander V.; Levenko, Borislav A.

    1995-02-01

    Laser Doppler microscopy is an efficient method of in vivo measurements of flow velocities in different biological objects. It is based on the registration of frequency shifts in light quasielastically scattered from particles moving in the flows. To study the embryonic development of the cardiac-vascular system in embryos of warm water fishes, embryos of Macropodus opercularis have been used. Doppler spectra from pulsatile blood flows in selected vessels and their changes in the process of ontogenesis have been registered. The recording of the successive spectra and their computer processing yield the varying dynamics of blood flows. Typical age dependencies of velocity patterns in the embryos are presented.

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

    Ketsaya Vacharanukul

    2006-06-01

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

  16. Flowmeter evaluation for on-orbit operations

    Baird, R. S.

    1988-08-01

    Various flowmetering concepts were flow tested to characterize the relative capabilities and limitations for on-orbit fluid-transfer operations. Performance results and basic operating principles of each flowmetering concept tested are summarized, and basic considerations required to select the best flowmeter(s) for fluid system application are discussed. Concepts tested were clamp-on ultrasonic, area averaging ultrasonic, offset ultrasonic, coriolis mass, vortex shedding, universal venturi tube, turbine, bearingless turbine, turbine/turbine differential-pressure hybrid, dragbody, and dragbody/turbine hybrid flowmeters. Fluid system flowmeter selection considerations discussed are flowmeter performance, fluid operating conditions, systems operating environments, flowmeter packaging, flowmeter maintenance, and flowmeter technology. No one flowmetering concept tested was shown to be best for all on-orbit fluid systems.

  17. DETECTION ON MICRO-DOPPLER EFFECT BASED ON LASER COHERENT RADAR

    Sun Yang; Zhang Jun

    2012-01-01

    A laser coherent detection system of 1550 nm wavelength was presented,and experimental research on detecting micro-Doppler effect in a dynamic target was developed.In the study,the return signal in the time domain is decomposed into a set of components in different wavelet scales by multi-resolution wavelet analysis,and the components are associated with the vibrational motions in a target.Then micro-Doppler signatures are extracted by applying the reconstruction.During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrational signals and estimate the motion parameters successfully.The experimental results indicate that the system can effectively detect micro-Doppler information in a moving target,and the tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analysis and time-frequency analysis.

  18. Eye-safe,single-frequency pulsed all-fiber laser for Doppler wind lidar

    Yuan Liu; Jiqiao Liu; Weibiao Chen

    2011-01-01

    @@ A single-frequency pulsed erbium-doped fiber(EDF)laser with master-oscillator Dower-amplifier comiguration at t bass nm is developed.A short-cavity,erbium-doped phosphate class fiber laser is utilized as a seeaer laser wntn a unewidtn of b khz and power of 40 mW.The seeder laser is modulated to be a pulse laser with a repetition rate of 10 kHz and pulse duration of 500 ns.The amplifier consists of two pre-amplifiers and one main amplifier.The detailed characteristics of the spectrum and linewidth of the amplifiers are presented.A pulse energy of 116 pJ and a linewidth of 1.1 MHz are obtained.This laser can be a candidate transmitter for an all-fiber Doppler wind lidar in the boundarv laver.%A single-frequency pulsed erbium-doped fiber (EDF) laser with master-oscillator power-amplifier configuration at 1533 nm is developed. A short-cavity, erbium-doped phosphate glass fiber laser is utilized as a seeder laser with a linewidth of 5 kHz and power of 40 mW. The seeder laser is modulated to be a pulse laser with a repetition rate of 10 kHz and pulse duration of 500 ns. The amplifier consists of two pre-amplifiers and one main amplifier. The detailed characteristics of the spectrum and linewidth of the amplifiers are presented. A pulse energy of 116 μJ and a linewidth of 1.1 MHz are obtained. This laser can be a candidate transmitter for an all-fiber Doppler wind lidar in the boundary layer.

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

    Broučková Zuzana

    2015-01-01

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

  20. Laser Doppler Vibrometer: Application of DOE/Taguchi Methodologies to Pyroshock Response Spectra

    C. J. Litz

    1997-01-01

    Full Text Available Statistical methodologies were employed for measuring and analyzing the explosively induced transient responses of a flat steel plate excited with shock. The application of design of experiment methodology was made to structure and test a Taguchi L9(32 full factorial experimental matrix (which uses nine tests to study two factors, with each factor examined at three levels in which a helium-neon laser Doppler vibrometer and two piezocrystal accelerometers were used to monitor explosively induced vibrations ranging from 10 to 105 Hz on a 96 × 48 × 0.25 in. flat steel plate. Resulting conclusions were drawn indicating how these techniques aid in understanding the pyroshock phenomenon with respect to the effects and interrelationships of explosive-charge weight and location on the laser Doppler and contract accelerometer recording systems.

  1. Accurate flexural spring constant calibration of colloid probe cantilevers using scanning laser Doppler vibrometry

    Gates, Richard S.; Osborn, William A.; Shaw, Gordon A.

    2015-06-01

    Calibration of the flexural spring constant for atomic force microscope (AFM) colloid probe cantilevers provides significant challenges. The presence of a large attached spherical added mass complicates many of the more common calibration techniques such as reference cantilever, Sader, and added mass. Even the most promising option, AFM thermal calibration, can encounter difficulties during the optical lever sensitivity measurement due to strong adhesion and friction between the sphere and a surface. This may cause buckling of the end of the cantilever and hysteresis in the approach-retract curves resulting in increased uncertainty in the calibration. Most recently, a laser Doppler vibrometry thermal method has been used to accurately calibrate the normal spring constant of a wide variety of tipped and tipless commercial cantilevers. This paper describes a variant of the technique, scanning laser Doppler vibrometry, optimized for colloid probe cantilevers and capable of spring constant calibration uncertainties near ±1%.

  2. Reproducibility of the capsaicin-induced dermal blood flow response as assessed by laser Doppler perfusion imaging

    Van der Schueren, B J; Hoon, J.N.; Vanmolkot, F H; Van Hecken, A; Depre, M; Kane, S.A.; De Lepeleire, I; Sinclair, S R

    2007-01-01

    What is already known about this subjectCapsaicin rapidly produces local neurogenic inflammation (characterized by oedema and erythema) when locally administered to the human skin by binding to the TRPV1 receptor present on dermal sensory nerve endings.In nonhuman primates, a pharmacodynamic assay has been described and validated using capsaicin-induced dermal vasodilation measured by laser Doppler perfusion imaging to assess calcitonin gene-related peptide antagonist activity.Laser Doppler p...

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

    Van den Brande, P; Welch, W

    1988-01-01

    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

  4. Intracerebral microvascular measurements during deep brain stimulation implantation using laser doppler perfusion monitoring

    Wårdell, Karin; Blomstedt, P.; Richter, Johan; Antonsson, Johan; Eriksson, Ola; Zsigmond, Peter; Bergenheim, A.T.; Hariz, M I.

    2007-01-01

    The aim of the study was to investigate if laser Doppler perfusion monitoring (LDPM) can be used in order to differentiate between gray and white matter and to what extent microvascular perfusion can be recorded in the deep brain structures during stereotactic neurosurgery. An optical probe constructed to fit in the Leksell® Stereotactic System was used for measurements along the trajectory and in the targets (globus pallidus internus, subthalamic nucleus, zona incerta, thalamus) during the i...

  5. Quantitative analysis of skin flap blood flow in the rat using laser Doppler velocimetry.

    Marks, N J

    1985-01-01

    Two experiments carried out on rat skin flaps are described, where microvascular flow has been measured noninvasively by a laser Doppler velocimeter. Using this technique it is possible to define the limits of an axial pattern flap in terms of microvascular flow; this was found to increase when the flap is elevated. 'Random-pattern' perfusion is defined by a fall in flow. This recovers sequentially along the flap, and at a constant rate at all sites. A differential in microvascular perfusion ...

  6. Analysis of Signal-to-Noise Ratio of the Laser Doppler Velocimeter

    Lading, Lars

    1973-01-01

    The signal-to-shot-noise ratio of the photocurrent of a laser Doppler anemometer is calculated as a function of the parameters which describe the system. It is found that the S/N is generally a growing function of receiver area, that few large particles are better than many small ones, and that...... generally the "fringe" or l"differential" mode configuration is equal to, or better than, the "reference beam" mode....

  7. Laser Doppler Vibrometer: Application of DOE/Taguchi Methodologies to Pyroshock Response Spectra

    C. J. Litz

    1997-01-01

    Statistical methodologies were employed for measuring and analyzing the explosively induced transient responses of a flat steel plate excited with shock. The application of design of experiment methodology was made to structure and test a Taguchi L9(32) full factorial experimental matrix (which uses nine tests to study two factors, with each factor examined at three levels) in which a helium-neon laser Doppler vibrometer and two piezocrystal accelerometers were used to monitor explosively ind...

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

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

    2013-01-01

    INTRODUCTION: In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench. OBJECTIVE: To compare unid...

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

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

    2013-01-01

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

  10. Ultrasonic flowmeters: half-century progress report, 1955-2005.

    Lynnworth, L C; Liu, Yi

    2006-12-22

    Ultrasonic flowmeters are one of the fastest-growing technologies within the general field of instruments for process monitoring, measurement and control. Today, acoustic/ultrasonic flowmeters utilize clamp-on and wetted transducers, single and multiple paths, paths on and off the diameter, passive and active principles, contrapropagating transmission, reflection (Doppler), tag correlation, vortex shedding, liquid level sensing of open channel flow or flow in partially-full conduits, and other interactions. Ultrasonic flowmeters are applicable to liquids, gases, and multiphase mixtures, but not without limits. However, no single technology, nor one type of interaction within a technology, can be best for all fluids, occasions and situations. Users who select a particular type of ultrasonic flowmeter over one based on a competing (nonultrasonic) technology often do so for one (or more) of the following reasons: ultrasonic equipment provides a useful measurement whether the fluid is single-phase or not single-phase; equipment is easy to use; flow regime can be laminar, transitional or turbulent; transducers are totally external (no penetration of the pressure boundary); transducers, if not clamp-on, are minimally invasive; no excess pressure drop; when certain conditions are met, accuracy can be better than 0.5%; fast (ms) response; reliable despite temperature extremes; reasonable purchase price, installation, operating and maintenance costs. Sometimes mass flowrate is obtainable. Energy flowrate might be achieved for natural gas and biogas in the near future. How did ultrasonic flowmeters advance in the past fifty years to support such claims? This paper tries to answer this question by looking at ultrasonic flowmeter inventions and publications since 1955, to see how four key problems were solved. PMID:16782156

  11. A Systematic Review of the Evolution of Laser Doppler Techniques in Burn Depth Assessment

    Manaf Khatib

    2014-01-01

    Full Text Available Aims. The introduction of laser Doppler (LD techniques to assess burn depth has revolutionized the treatment of burns of indeterminate depth. This paper will systematically review studies related to these two techniques and trace their evolution. At the same time we hope to highlight current controversies and areas where further research is necessary with regard to LD imaging (LDI techniques. Methods. A systematic search for relevant literature was carried out on PubMed, Medline, EMBASE, and Google Scholar. Key search terms included the following: “Laser Doppler imaging,” “laser Doppler flow,” and “burn depth.” Results. A total of 53 studies were identified. Twenty-six studies which met the inclusion/exclusion criteria were included in the review. Conclusions. The numerous advantages of LDI over those of LD flowmetry have resulted in the former technique superseding the latter one. Despite the presence of alternative burn depth assessment techniques, LDI remains the most favoured. Various newer LDI machines with increasingly sophisticated methods of assessing burn depth have been introduced throughout the years. However, factors such as cost effectiveness, scanning of topographically inconsistent areas of the body, and skewing of results due to tattoos, peripheral vascular disease, and anaemia continue to be sighted as obstacles to LDI which require further research.

  12. Full-field high-speed laser Doppler imaging system for blood-flow measurements

    Serov, Alexandre; Lasser, Theo

    2006-02-01

    We describe the design and performance of a new full-field high-speed laser Doppler imaging system developed for mapping and monitoring of blood flow in biological tissue. The total imaging time for 256x256 pixels region of interest is 1.2 seconds. An integrating CMOS image sensor is utilized to detect Doppler signal in a plurality of points simultaneously on the sample illuminated by a divergent laser beam of a uniform intensity profile. The integrating property of the detector improves the signal-to-noise ratio of the measurement, which results in high-quality flow-images provided by the system. The new technique is real-time, non-invasive and the instrument is easy to use. The wide range of applications is one of the major challenges for a future application of the imager. High-resolution high-speed laser Doppler perfusion imaging is a promising optical technique for diagnostic and assessing the treatment effect of the diseases such as e.g. atherosclerosis, psoriasis, diabetes, skin cancer, allergies, peripheral vascular diseases, skin irritancy and wound healing. We present some biological applications of the new imager and discuss the perspectives for the future implementations of the imager for clinical and physiological applications.

  13. Laser-doppler sensor system for speed and length measurements at moving surfaces

    Stork, Wilhelm; Wagner, Armin; Kunze, Carsten

    2001-10-01

    Laser-Doppler Velocimetry is a contact less method for measuring the speed and the path length of moving solid- state surfaces or of fluid streams. In the past the main application of this method was fluid mechanics. No other method was as suitable as Laser-Doppler Anemometry to measure the speed the streams at arbitrary positions. Therefore the market accepted the very high price of these systems. In the past for the measurement of solid-state surfaces mostly other methods with a more reasonable price were used. However from a pure technical point of view a contact less and precise method as Laser-Doppler Velocimetry is also very attractive for the measurement of solid-state surfaces. The method is suitable for nearly any type of technical surface. The measurement procedure does not damage the surfaces and no slippage occurs. These advantages will be become important also for standard applications, if the price of the LDV systems can compete with the price of other methods.

  14. Wind Doppler lidar with 1.5 μm fiber laser

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

  15. Ultrasonic flowmeter for JSFR

    The piping materials of the Japan Sodium-Cooled Fast Reactor (JSFR) at the commercialized stage, will be ferromagnetic materials Mod. 9-Cr steel.Therefore, it is not feasible to adopt the electromagnetic flowmeters used in conventional FBR plants. This paper describes the developmental status of the ultrasonic flowmeter system (USFM) as a substitute flow rate measurement system to JSFR. The features of the USFM are the following; In consideration of the double wall piping structure on JSFR, ultrasonic transducers should be installed directly on the surface of the inner primary coolant pipe. Therefore, the transducers should work properly under the temperature of 395 degrees Cat the rated power, and be replaced by remote replacement system; The transducer remote exchange system should maintain with air tightness between the inner primary coolant piping and the outer piping during the normal plant operation, apply appropriate pressure to the transducers against the inner primary coolant piping, and exchange the transducers without removing the outer piping under the maintenance outage; Multi-pass propagation time method is effective for detection of flow rate in the short entrance region (e.g. in the short straight piping) and the requirements of the signal processing equipment are the following; Linearity and repeatability of output signal : less than± 2% of Full Scale; Fluctuation rate of output signal : less than ± 5% of median; Response : less than 0.3 s; The USFM is designed as one of the Safety Protection System

  16. Ultrasonic Flowmeter for JSFR

    The piping materials of the Japan Sodium-Cooled Fast Reactor (JSFR) at the commercialized stage, will be ferromagnetic materials Mod. 9-Cr steel. Therefore, it is not feasible to adopt the electromagnetic flowmeters used in conventional FBR plants. This paper describes the developmental status of the ultrasonic flowmeter system (USFM) as a substitute flow rate measurement system for JSFR. The features of the USFM are the following; - In consideration of the double wall piping structure of JSFR, ultrasonic transducers should be installed directly on the surface of the inner primary coolant piping. Therefore, the transducers should work properly under 395 oC at the rated power, and be replaced by a remote replacement system. - The transducer remote replacement system should maintain the air tightness between the inner primary coolant piping and the outer piping during the normal plant operation, apply appropriate pressure to the transducers against the inner primary coolant piping, and replace the transducers without removing the outer piping under the maitenance outage. - The multi-pass propagation time method is effective for detection of the flow rate in the short entrance region (in the short straight piping). The requirements of the signal processor are the following; Linearity and repeatability of the output signal : ± 2% or less of full scale; Fluctuation rate of the output signal : ± 5% or less of the median; Response : 0.3 s or less. - The USFM is designed as one of the safety protection system. (author)

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

    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 μm . 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

  18. A tunable Doppler-free dichroic lock for laser frequency stabilization

    Singh, Vivek; Mishra, S R; Rawat, H S

    2016-01-01

    We propose and demonstrate a laser frequency stabilization scheme which generates a dispersion-like tunable Doppler-free dichroic lock (TDFDL) signal. This signal offers a wide tuning range for lock point (i.e. zero-crossing) without compromising on the slope of the locking signal. The method involves measurement of magnetically induced dichroism in an atomic vapour for a weak probe laser beam in presence of a counter propagating strong pump laser beam. A simple model is presented to explain the basic principles of this method to generate the TDFDL signal. The spectral shift in the locking signal is achieved by tuning the frequency of the pump beam. The TDFDL signal is shown to be useful for locking the frequency of a cooling laser used for magneto-optcal trap (MOT) for $^{87}Rb$ atoms.

  19. A tunable Doppler-free dichroic lock for laser frequency stabilization

    Singh, Vivek; Tiwari, V. B.; Mishra, S. R.; Rawat, H. S.

    2016-08-01

    We propose and demonstrate a laser frequency stabilization scheme which generates a dispersion-like tunable Doppler-free dichroic lock (TDFDL) signal. This signal offers a wide tuning range for lock point (i.e. zero-crossing) without compromising on the slope of the locking signal. The method involves measurement of magnetically induced dichroism in an atomic vapour for a weak probe laser beam in the presence of a counter-propagating strong pump laser beam. A simple model is presented to explain the basic principles of this method to generate the TDFDL signal. The spectral shift in the locking signal is achieved by tuning the frequency of the pump beam. The TDFDL signal is shown to be useful for locking the frequency of a cooling laser used for magneto-optical trap (MOT) for 87 Rb atoms.

  20. Ultrasonic flowmeters that are insensitive to suspended solids

    Averett, William J.

    1990-10-01

    The results of an investigation of the performance of state of the art and standard porable ultrasonic Doppler flowmeters that do not require particles or bubbles in the fluid to make an accurate measurement are described. Both the standard and new state of the art flowmeters measured flow within their claimed accuracy in tap water without any particles of bubbles added. All testing was performed at the U.S. EPA Test and Evaluation Facility in Cincinnati, Ohio. All testing conformed to Scientific Apparatus Makers Association (SAMA) standards. The test results from both flowmeters are presented so that an easy comparison may be made and that the improvement in performance can be determined. The velocity range of all testing was from 0-21.58 ft/second. The state of the art ultrasonic flowmeter was superior in measuring lower values of flow and performed about the same as the control flow meter over the upper range of the velocities tested. However, these advancements in ultrasonic technology do not abrogate the normal loss of accuracy above 16.25 ft/second in tap water. The loss seems to be a function of Reynolds number.

  1. Experimental study on minimum resolvable velocity for heterodyne laser Doppler vibrometry

    Jianhua Shang; Shuguang Zhao; Yan He; Weibiao Chen; Ning Jia

    2011-01-01

    A high spatial resolution, high velocity resolution all-fiber laser Doppler vibrornetry (LDV) based on heterodyne detection for vibration measurements is reported. A linewidth of 1-kHz single-mode continuous fiber laser, polarization-preserving fiber, and a telescope with 30-mm aperture are used in this LDV. With the inphase-quadrature circuit and the digital differentiating discriminator, a high velocity resolution of 96.9 nm/s and a high displacement resolution of 2.5 pm are obtained simultaneously with a glass attached to a piezoceramic transducer. These values correspond to the measurement uncertainties of vibration velocity and displacement within 4.14% and 4.6%, respectively.%@@ A high spatial resolution,high velocity resolution all-fiber laser Doppler vibrometry(LDV) based on heterodyne detection for vibration measurements is reported.A linewidth of 1-kHz single-mode continuous fiber laser,polarization-preserving fiber,and a telescope with 30-mm aperture are used in this LDV.

  2. Noninvasive In-vivo Measurements of Microvessels by Reflection-Type Micro Multipoint Laser Doppler Velocimeter

    Ishida, Hiroki; Andoh, Tsugunobu; Akiguchi, Shunsuke; Hachiga, Tadashi; Ishizuka, Masaru; Shimizu, Tadamichi; Shirakawa, Hiroki; Kuraishi, Yasushi

    2012-03-01

    We have developed a micro multipoint laser Doppler velocimeter (µ-MLDV) that enables selective collection of Doppler interference photons. In previous report [H. Ishida et al.: Rev. Sci. Instrum. 82 (2011) 076104], developed the reflection-type µ-MLDV, and showed the results of demonstrations performed on transparent artificial flow channels. In this study, we attempted to perform in-vivo experiments using animals. It can measure absolute velocity and generate tomographs of blood vessels courses. The present system can perform noninvasive in-vivo measurements with a detection limit of about 0.5 mm/s and a spatial resolution in the x-y plane of 125 µm. It is thus able to image venulae. It was used to image venulae in a mouse ear and a subcutaneous blood vessel in a mouse abdomen at a depth of about 1.0 mm below the skin.

  3. Spatially resolved sub-Doppler overtone gain measurements on a small-scale supersonic HF laser

    Wisniewski, Charles F.; Hewett, Kevin B.; Manke, Gerald C., II; Truman, C. Randall; Hager, Gordon D.

    2004-05-01

    The small signal gain of a small-scale HF overtone laser was measured using a sub-Doppler tunable diode laser system. Measurements of reactant concentration, flow velocity and gain length were also made. The spatially resolved, two-dimensional small signal gain and temperature maps that were generated show a highly inhomogeneous gain medium indicating the dominant role played by mixing of the H2 and F streams in HF laser performance. The measured gain and temperature data were analyzed with the aid of a two-dimensional computational fluid dynamics model. The results show that reactant mixing mechanisms have a large effect on the gain averaged over a vertical profile while kinetic rate mechanisms, including reaction rate constants and reactant concentration, have a greater effect on the maximum system gain.

  4. Development of semiconductor laser based Doppler lidars for wind-sensing applications

    Rodrigo, Peter John; Hu, Qi; Pedersen, Christian

    2015-01-01

    We summarize the progress we have made in the development of semiconductor laser (SL) based Doppler lidar systems for remote wind speed and direction measurements. The SL emitter used in our wind-sensing lidar is an integrated diode laser with a tapered (semiconductor) amplifier. The laser source...... is low-cost and compact - enhancing the potential of lidar wind sensors for mass production. This paper describes two embodiments of the patented wind lidar technology and presents experimental results that evaluate the wind sensors' performance. Due to compactness, portability and cost-efficiency, SL...... based wind sensors have a strong potential in a number of applications such as wind turbine control, wind resource assessment, and micrometeorology (e.g. as alternative to the construction of meteorological towers with anemometers and wind vanes)....

  5. Eulerian laser Doppler vibrometry: Online blade damage identification on a multi-blade test rotor

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

    2011-01-01

    Laser Doppler vibrometry enables the telemetry-free measurement of online turbomachinery blade vibration. Specifically, the Eulerian or fixed reference frame implementation of laser vibrometry provides a practical solution to the condition monitoring of rotating blades. The short data samples that are characteristic of this measurement approach do however negate the use of traditional frequency domain signal processing techniques. It is therefore necessary to employ techniques such as time domain analysis and non-harmonic Fourier analysis to obtain useful information from the blade vibration signatures. The latter analysis technique allows the calculation of phase angle trends which can be used as indicators of blade health deterioration, as has been shown in previous work for a single-blade rotor. This article presents the results from tests conducted on a five-blade axial-flow test rotor at different rotor speeds and measurement positions. With the aid of artificial neural networks, it is demonstrated that the parameters obtained from non-harmonic Fourier analysis and time domain signal processing on Eulerian laser Doppler vibrometry signals can successfully be used to identify and quantify blade damage from among healthy blades. It is also shown that the natural frequencies of individual blades can be approximated from the Eulerian signatures recorded during rotor run-up and run-down.

  6. Doppler laser imaging predicts response to topical minoxidil in the treatment of female pattern hair loss.

    McCoy, J; Kovacevic, M; Situm, M; Stanimirovic, A; Bolanca, Z; Goren, A

    2016-01-01

    Topical minoxidil is the only drug approved by the US FDA for the treatment of female pattern hair loss. Unfortunately, following 16 weeks of daily application, less than 40% of patients regrow hair. Several studies have demonstrated that sulfotransferase enzyme activity in plucked hair follicles predicts topical minoxidil response in female pattern hair loss patients. However, due to patients’ discomfort with the procedure, and the time required to perform the enzymatic assay it would be ideal to develop a rapid, non-invasive test for sulfotransferase enzyme activity. Minoxidil is a pro-drug converted to its active form, minoxidil sulfate, by sulfotransferase enzymes in the outer root sheath of hair. Minoxidil sulfate is the active form required for both the promotion of hair regrowth and the vasodilatory effects of minoxidil. We thus hypothesized that laser Doppler velocimetry measurement of scalp blood perfusion subsequent to the application of topical minoxidil would correlate with sulfotransferase enzyme activity in plucked hair follicles. In this study, plucked hair follicles from female pattern hair loss patients were analyzed for sulfotransferase enzyme activity. Additionally, laser Doppler velocimetry was used to measure the change in scalp perfusion at 15, 30, 45, and 60 minutes, after the application of minoxidil. In agreement with our hypothesis, we discovered a correlation (r=1.0) between the change in scalp perfusion within 60 minutes after topical minoxidil application and sulfotransferase enzyme activity in plucked hairs. To our knowledge, this is the first study demonstrating the feasibility of using laser Doppler imaging as a rapid, non-invasive diagnostic test to predict topical minoxidil response in the treatment of female pattern hair loss. PMID:27049083

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

    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)

  8. Determination of air and hydrofoil pressure coefficient by laser doppler anemometry

    Ristić Slavica S.

    2010-01-01

    Full Text Available Some results of experiments performed in water cavitation tunnel are presented. Pressure coefficient (Cp was experimentally determined by Laser Doppler Anemometry (LDA measurements. Two models were tested: model of airplane G4 (Super Galeb and hydrofoil of high speed axial pump. These models are not prepared for conventional pressure measurements, so that LDA is applied for Cp determination. Numerical results were obtained using a code for average Navier-Stokes equations solutions. Comparisons between computational and experimental results prove the effectiveness of the LDA. The advantages and disadvantages of LDA application are discussed. Flow visualization was made by air bubbles.

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

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

    2013-01-01

    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 offer...

  10. Acute radiation effects on cutaneous microvasculature: evaluation with a laser Doppler perfusion monitor

    Laser Doppler perfusion monitoring is a noninvasive technique for measuring blood flow in epidermal microvasculature that makes use of the frequency shift of light reflected from red blood cells. Measurements in patients undergoing radiation therapy show increases in blood flow of ten to 25 times baseline at doses above 50 Gy, and increases are observed with doses as low as 2 Gy. Follow-up measurements show rapid decreases in flow levels after completion of therapy, but levels remain elevated even at 1 year

  11. Acute radiation effects on cutaneous microvasculature: evaluation with a laser Doppler perfusion monitor

    Amols, H.I.; Goffman, T.E.; Komaki, R.; Cox, J.D.

    1988-11-01

    Laser Doppler perfusion monitoring is a noninvasive technique for measuring blood flow in epidermal microvasculature that makes use of the frequency shift of light reflected from red blood cells. Measurements in patients undergoing radiation therapy show increases in blood flow of ten to 25 times baseline at doses above 50 Gy, and increases are observed with doses as low as 2 Gy. Follow-up measurements show rapid decreases in flow levels after completion of therapy, but levels remain elevated even at 1 year.

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

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

    2009-04-06

    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.

  13. Support of gas flowmeter upgrade

    Waugaman, Dennis

    1996-01-01

    A project history review, literature review, and vendor search were conducted to identify a flowmeter that would improve the accuracy of gaseous flow measurements in the White Sands Test Facility (WSTF) Calibration Laboratory and the Hydrogen High Flow Facility. Both facilities currently use sonic flow nozzles to measure flowrates. The flow nozzle pressure drops combined with corresponding pressure and temperature measurements have been estimated to produce uncertainties in flowrate measurements of 2 to 5 percent. This study investigated the state of flowmeter technology to make recommendations that would reduce those uncertainties. Most flowmeters measure velocity and volume, therefore mass flow measurement must be calculated based on additional pressures and temperature measurement which contribute to the error. The two exceptions are thermal dispersion meters and Coriolis mass flowmeters. The thermal dispersion meters are accurate to 1 to 5 percent. The Coriolis meters are significantly more accurate, at least for liquids. For gases, there is evidence they may be accurate to within 0.5 percent or better of the flowrate, but there may be limitations due to inappropriate velocity, pressure, Mach number and vibration disturbances. In this report, a comparison of flowmeters is presented. Candidate Coriolis meters and a methodology to qualify the meter with tests both at WSTF and Southwest Research Institute are recommended and outlined.

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

    Chepurov, S V; Lugovoy, A A; Kuznetsov, S N [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2014-06-30

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

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

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

    2012-06-01

    The paper presents an optical non-contact method for simultaneous measurement of the heart beat and respiration period, based on the assessment of the chest wall movements induced by the pumping action of the heart, and by inspiration/expiration acts of the lungs. The measurement method is applied on 40 patients recovered in a Neonatal Intensive Care Unit (NICU), where the operating conditions are often critical and the contact with the patient's skin needs to be minimized. The method proposed is based on optical recording of the movements of chest wall by means of a laser Doppler vibrometer directly pointed onto the left, frontal part of the thoracic surface. Data measured were compared with reference instrumentation; to reach this goal, the ECG and Laser Doppler Vibrometer (LDV) signals were simultaneously acquired to monitor the heart period (HP), while to measure respiration period (RP) signals from a spirometer and a LDV were collected simultaneously. After LDV signals decomposition, heart and respiration acts were detected and compared in term of beat per minute (bpm). HPs measured by the proposed method showed an uncertainty ECG), while for RPs data an uncertainty of 3% (respect to spirometer data) was estimated. The proposed method has the intrinsic advantage to be totally without contact and to allow the simultaneous measurement of heart and respiration rate also in critical, clinical environments such as the NICU.

  16. Assesment of gingival microcirculation in anterior teeth using laser Doppler flowmetry

    Canjau, Silvana; Miron, Mariana I.; Todea, Carmen D.

    2016-03-01

    Introduction: Evaluating the health status of the gingival tissue represents an important objective in the daily practice. Inflammation changes the microcirculatory and micromorphological dynamics of human gingiva. Aim: The purpose of this study was to evaluate the microcirculation in subjects with moderate gingivitis and healthy gingiva by using laser Doppler flowmetry (LDF). Material and Methods: Recordings of the gingival microcirculation (GM) were taken from 20 healthy gingival sites and from 20 sites with moderate gingivitis. The gingival blood flows in the gingivitis group before treatment was significantly different from those in the healthy gingiva group. Signals were recorded with the aid of a laser Doppler MoorLab instrument VMS-LDF2 probe VP3 10 mm S/N 2482. Three consecutive determinations of the GM were registered for each site, as follows: before the initial therapy, at 24 hours after the initial therapy and then, 7 days after the initial therapy. The data were processed using the statistical analysis software SPSS v16.0.1. Results: The results of this preliminary study showed statistically significant differences among the GM values recorded before and after the initial therapy. Conclusions: LDF could be a useful, noninvasive, sensitive, reproducible, and harmless method for measuring gingival blood flow (gingival microcirculation) in humans.

  17. High-speed laser Doppler perfusion imaging using an integrating CMOS image sensor.

    Serov, Alexandre; Lasser, Theo

    2005-08-22

    This paper describes the design and the performance of a new high-speed laser Doppler imaging system for monitoring blood flow over an area of tissue. The new imager delivers high-resolution flow images (256x256 pixels) every 2 to 10 seconds, depending on the number of points in the acquired time-domain signal (32-512 points). This new imaging modality utilizes a digital integrating CMOS image sensor to detect Doppler signals in a plurality of points over the area illuminated by a divergent laser beam of a uniform intensity profile. The integrating property of the detector improves the signal-to-noise ratio of the measurements, which results in high-quality flow images. We made a series of measurements in vitro to test the performance of the system in terms of bandwidth, SNR, etc. Subsequently we give some examples of flow-related images measured on human skin, thus demonstrating the performance of the imager in vivo. The perspectives for future implementations of the imager for clinical and physiological applications are discussed. PMID:19498655

  18. Flow angle dependent photoacoustic Doppler power spectra under intensity-modulated continuous wave laser excitation

    Yu Tong

    2016-02-01

    Full Text Available Photoacoustic Doppler (PAD power spectra showing an evident Doppler shift represent the major characteristics of the continuous wave-excited or burst wave-excited versions of PAD flow measurements. In this paper, the flow angle dependences of the PAD power spectra are investigated using an experiment setup that was established based on intensity-modulated continuous wave laser excitation. The setup has an overall configuration that is similar to a previously reported configuration, but is more sophisticated in that it accurately aligns the laser illumination with the ultrasound detection process, and in that it picks up the correct sample position. In the analysis of the power spectra data, we find that the background power spectra can be extracted by combining the output signals from the two channels of the lock-in amplifier, which is very useful for identification of the PAD power spectra. The power spectra are presented and analyzed in opposite flow directions, at different flow speeds, and at different flow angles. The power spectra at a 90° flow angle show the unique properties of symmetrical shapes due to PAD broadening. For the other flow angles, the smoothed power spectra clearly show a flow angle cosine relationship.

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

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

    2013-12-01

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

  20. Scanning Laser Doppler Vibrometry Application to Artworks: New Acoustic and Mechanical Exciters for Structural Diagnostics

    Agnani, A.; Esposito, E.

    After first attempts some years ago, the scanning laser Doppler vibrometer has become an effective way of diagnosing different types of artworks; successful applications regard frescoes, icons, mosaics, ceramic artefacts and wood inlays. Also application to historical bridges has been successfully developed and a recently approved European Commission project will see the employment of scanning laser Doppler Vibrometry (SLDV) for the dynamical characterization of ancient buildings. However, a critical issue consists in the adequate excitation of the structure under test. Moreover different types of defects and different kinds of artworks require different types of excitation, so this topic needs a deep consideration. In this work we will present two new types of exciters developed at our Department, namely an acoustic exciter and a mechanical one. Acoustic exciters allow remote non-invasive loading but are limited in the lower frequency range and in the amount of vibrational energy input into the structure. The proposed automatic tapping device based on a commercial impact hammer overcomes these problems. Also another acoustic exciter, a HyperSonic Sound (HSS) source has been evaluated, showing interesting features as regards sound radiation.

  1. Rotating blade vibration analysis using photogrammetry and tracking laser Doppler vibrometry

    Gwashavanhu, Benjamin; Oberholster, Abrie J.; Heyns, P. Stephan

    2016-08-01

    Online structural dynamic analysis of turbomachinery blades is conventionally done using contact techniques such as strain gauges for the collection of data. To transfer the captured data from the sensor to the data logging system, installation of telemetry systems is required. This is usually complicated, time consuming and may introduce electrical noise into the data. In addition, contact techniques are intrusive by definition and can introduce significant local mass loading. This affects the integrity of the captured measurements. Advances in technology now allow for the use of optical non-contact methods to analyse the dynamics of rotating structures. These include photogrammetry and tracking laser Doppler vibrometry (TLDV). Various investigations to establish the integrity of photogrammetry measurements for rotating structures involved a comparison to data captured using accelerometers. Discrepancies that were noticed were attributed to the intrusive nature of the contact measurement technique. As an extended investigation, the presented work focuses on the validation of photogrammetry applied to online turbomachinery blade measurements, using TLDV measurements. Through a frequency based characterisation approach of the dynamics of the two scanning mirrors inside the scanning head of a scanning laser Doppler vibrometer (SLDV), TLDV is employed in developing a system that can be used to achieve a perfect circular scan with a Polytec SLDV, (PSV 300). Photogrammetry out-of-plane displacements of a laser dot focused on a specific point on a rotating blade are compared to displacements captured by the laser scanning system. It is shown that there is good correlation between the two measurement techniques when applied to rotating structures, both in the time and frequency domains. The presence of slight discrepancies between the two techniques after elimination of accelerometer based errors illustrated that the optical system noise floor of photogrammetry does

  2. Instrument-independent flux units for laser doppler perfusion monitoring assessed in a multi-device study on the renal cortex

    Petoukhova, A.L.; Steenbergen, W.; Morales, F.; Graaff, R.; Jong, de E.D.; Elstrodt, J.M.; Mul, de F.F.M.; Rakhorst, G.

    2003-01-01

    To investigate the feasibility of instrument-independent perfusion units for laser Doppler flowmetry, a comparison was performed of two commercial fiberoptic laser Doppler perfusion monitors measuring the same flux situation for two different types of probes. In vivo measurements were performed on t

  3. Instrument-independent flux units for laser Doppler perfusion monitoring assessed in a multi-device study on the renal cortex

    Petoukhova, AL; Steenbergen, W; Morales, F; Graaff, R; de Jong, ED; Elstrodt, JM; de Mul, FFM; Rakhorst, G

    2003-01-01

    To investigate the feasibility of instrument-independent perfusion units for laser Doppler flowmetry, a comparison was performed of two commercial fiberoptic laser Doppler perfusion monitors measuring the same flux situation for two different types of probes. In vivo measurements were performed on t

  4. Qualification Testing of Laser Diode Pump Arrays for a Space-Based 2-micron Coherent Doppler Lidar

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    The 2-micron thulium and holmium-based lasers being considered as the transmitter source for space-based coherent Doppler lidar require high power laser diode pump arrays operating in a long pulse regime of about 1 msec. Operating laser diode arrays over such long pulses drastically impact their useful lifetime due to the excessive localized heating and substantial pulse-to-pulse thermal cycling of their active regions. This paper describes the long pulse performance of laser diode arrays and their critical thermal characteristics. A viable approach is then offered that allows for determining the optimum operational parameters leading to the maximum attainable lifetime.

  5. The doppler frequency shift caused by the inhomogeneities of a medium induced by pulses of intense laser radiation

    Rozanov, N. N.; Kiselev, Al. S.; Kiselev, An. S.

    2008-08-01

    Self-reflection of pulses of intense laser radiation from an inhomogeneity induced by them in a medium with fast optical nonlinearity is analyzed. The reflected radiation is characterized by a considerable Doppler shift and by a signal magnitude that is sufficient for experimental detection.

  6. Evaluation of a new high power, wide separation laser Doppler probe : Potential measurement of deeper tissue blood flow

    Clough, Geraldine; Chipperfield, Andrew; Byrne, Christopher; de Mul, Frits; Gush, Rodney

    2009-01-01

    Objective: To compare the output from a novel high power, wide separation laser Doppler flow probe (DP1-V2-HP, 4 mm, with IRLD20) with that of a standard flow probe (DP1-V2, 0.5 mm, with DRT4) (Moor UK) and to explore its potential for use in the noninvasive measurement of blood flow in deeper tissu

  7. Applying laser Doppler anemometry inside a Taylor-Couette geometry using a ray-tracer to correct for curvature effects

    Huisman, S.G.; Gils, van D.P.M.; Sun, C.

    2012-01-01

    In the present work it will be shown how the curvature of the outer cylinder affects laser Doppler anemometry measurements inside a Taylor¿Couette apparatus. The measurement position and the measured velocity are altered by curved surfaces. Conventional methods for curvature correction are not appli

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

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

  9. 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

    Nunez, Silvia Cristina

    2002-07-01

    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)

  10. Eye-safe diode laser Doppler lidar with a MEMS beam-scanner

    Hu, Qi; Pedersen, Christian; Rodrigo, Peter John

    2016-01-01

    We present a novel Doppler lidar that employs a cw diode laser operating at 1.5 μm and a micro-electro-mechanical-system scanning mirror (MEMS-SM). In this work, two functionalities of the lidar system are demonstrated. Firstly, we describe the capability to effectively steer the lidar probe beam...... at the probing distance (R = 60 m) of each lineof-sight – relevant for meeting eye-safety requirements. The switching time of the MEMS-SM is measured to be in the order of a few milliseconds. Time-shared (0.25 s per line-of-sight) radial wind speed measurements at 50 Hz data rate are experimentally...

  11. Automatic measurement of field-dependent elastic modulus and damping by laser Doppler vibrometry

    A method for characterizing the magnetoelastic dependence of both Young's modulus and damping on the magnetic field is presented. It is based on laser Doppler vibrometry and free longitudinal vibration in soft ferromagnetic rods and wires, and offers a broad range of improved features including accuracy, lack of interaction with the sample, speed of measurement, full automation, high resolution and the possibility of stress-dependence studies. All these allow samples to be perfectly characterized in the full magnetic field range, estimating the behaviour of the specimen as different magnetization curves are followed and discovering critical points that had been overlooked in previous works. As an example, the magnetoelastic characterization of nickel rods is described, and excellent results are obtained which are consistent with the hysteresis loop of nickel and the theory of magnetic domains in ferromagnetic materials

  12. Perfusion assessment in rat spinal cord tissue using photoplethysmography and laser Doppler flux measurements

    Phillips, Justin P.; Cibert-Goton, Vincent; Langford, Richard M.; Shortland, Peter J.

    2013-03-01

    Animal models are widely used to investigate the pathological mechanisms of spinal cord injury (SCI), most commonly in rats. It is well known that compromised blood flow caused by mechanical disruption of the vasculature can produce irreversible damage and cell death in hypoperfused tissue regions and spinal cord tissue is particularly susceptible to such damage. A fiberoptic photoplethysmography (PPG) probe and instrumentation system were used to investigate the practical considerations of making measurements from rat spinal cord and to assess its suitability for use in SCI models. Experiments to assess the regional perfusion of exposed spinal cord in anesthetized adult rats using both PPG and laser Doppler flowmetry (LDF) were performed. It was found that signals could be obtained reliably from all subjects, although considerable intersite and intersubject variability was seen in the PPG signal amplitude compared to LDF. We present results from 30 measurements in five subjects, the two methods are compared, and practical application to SCI animal models is discussed.

  13. Composite Characterization Using Laser Doppler Vibrometry and Multi-Frequency Wavenumber Analysis

    Juarez, Peter; Leckey, Cara

    2015-01-01

    NASA has recognized the need for better characterization of composite materials to support advances in aeronautics and the next generation of space exploration vehicles. An area of related research is the evaluation of impact induced delaminations. Presented is a non-contact method of measuring the ply depth of impact delamination damage in a composite through use of a Scanning Laser Doppler Vibrometer (SLDV), multi-frequency wavenumber analysis, and a wavenumber-ply correlation algorithm. A single acquisition of a chirp excited lamb wavefield in an impacted composite is post-processed into a numerous single frequency excitation wavefields through a deconvolution process. A spatially windowed wavenumber analysis then extracts local wavenumbers from the wavefield, which are then correlated to theoretical dispersion curves for ply depth determination. SLDV based methods to characterize as-manufactured composite variation using wavefield analysis will also be discussed.

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

    Au, Minnie; Rattigan, Stephen

    2012-01-01

    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. PMID:23382766

  15. Measurement of blood velocity using laser Doppler method for the designing module

    Chen, Guo-Liang; Lee, Jen-Ai; Lu, Tung-Wu; Chen, Zhao-Cheng; Chen, Chien-Ming

    2005-04-01

    We built the Dual Beam Mode of the LDA (Laser Doppler Anemometry) frame, set the photodetector at the same side with light source which collect the scattering light of blood cell. It's proper to reduce LDA optical path and convenient for our designing module. The concentration of chicken blood in this study is about 1% and we measured the relations actually between flood velocity and the angle of beams cross on particles, temperature, and the diameter of aqueduct. We found better results while the cross angle was less than 38.8 degree, diameter of aqueduct was 6 mm, and temperature of blood was set to 36 . These parameters can also provide important basis for the LDA module kit that we are designing.

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

    Tong-Miin Liou

    2001-01-01

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

  17. Doppler-free laser spectroscopy of buffer gas cooled molecular radicals

    Skoff, S M; Tarbutt, M R; Hudson, J J; Segal, D M; Sauer, B E; Hinds, E A

    2009-01-01

    We demonstrate Doppler-free saturated absorption spectroscopy of cold molecular radicals formed by laser ablation inside a cryogenic buffer gas cell. By lowering the temperature, congested regions of the spectrum can be simplified, and by using different temperatures for different regions of the spectrum a wide range of rotational states can be studied optimally. We use the technique to study the optical spectrum of YbF radicals with a resolution of 30 MHz, measuring the magnetic hyperfine parameters of the electronic ground state. The method is suitable for high resolution spectroscopy of a great variety of molecules at controlled temperature and pressure, and is particularly well-suited to those that are difficult to produce in the gas phase.

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

    Crua, Cyril

    2015-01-01

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

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

    Rodrigo, Peter John; Pedersen, Christian

    2012-01-01

    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...... 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...... 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...

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

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

  1. SNR enhancement for composite application using multiple Doppler vibrometers based laser ultrasonic propagation imager

    Truong, Thanh Chung; Lee, Jung Ryul

    2016-09-01

    In recent years, the technology of using laser ultrasonic propagation imaging for damage visualization of composite structures were applied to real-world applications. Among many choices of sensor for the Ultrasonic Propagation Imager, the laser interferometry has several advantages: it is non-invasive, and portable, and with extraordinarily long-range measurement. However, the critical issue with interferometry sensing is its low signal-to-noise ratio (SNR), where the background noise can mask the damage-induced waves and making it impossible to identify the damages, especially in composite structures. In this paper, we propose a hardware-based SNR enhancement technique using multiple Laser Doppler Vibrometers (LDVs). The out-of-plane mode of ultrasonic signals are measured by multiple LDVs at a common sensing point and then averaged in real time. We showed that the SNR enhancement in experiments was consistent with the theoretical prediction, and also the test results showed a clear improvement for damage visualization of structures using Ultrasonic Wave Propagation Imaging and Ultrasonic Wavenumber Imaging algorithms.

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

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

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

    Campo, Adriaan; Dirckx, Joris

    2014-05-01

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

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

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

    2014-05-27

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

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

    Kim, Jae-Ihn

    2009-07-23

    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

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

    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 λω = 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, Λ-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

  7. Multiscale Compression Entropy of Microvascular Blood FlowSignals: Comparison of Results from Laser Speckle Contrastand Laser Doppler Flowmetry Data in Healthy Subjects

    Anne Humeau-Heurtier; Mathias Baumert; Guillaume Mahé; Pierre Abraham

    2014-01-01

    Microvascular perfusion is commonly used to study the peripheral cardiovascular system. Microvascular blood flow can be continuously and non-invasively monitored with laser speckle contrast imaging (LSCI) or with laser Doppler flowmetry (LDF). These two optical-based techniques give perfusion values in arbitrary units. Our goal is to better understand the perfusion time series given by each technique. For this purpose, we propose a nonlinear complexity analysis of LSCI and LDF time series rec...

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

    Lalitha T. Arunachalam

    2014-01-01

    Full Text Available Low level laser therapy (LLLT is widely used during the post-operative period to accelerate the healing process. It promotes beneficial biological action on neovascularization with anti-inflammatory and analgesic effects. Two systemically healthy patients with Miller′s grade II recession on 33 and 41, respectively, were treated with free gingival graft. After surgery, second patient received LLLT using a 830 nm diode laser, with output power of 0.1 W on the first day half hour following surgery, on the third day, seventh day, and lastly on the ninth day. Both the patients were asked to assess the pain on second, fourth and tenth day using a Numerical Rating Scale and revascularization of the grafted area was assessed using a color Doppler ultrasound imaging on the fourth and the ninth day. Neovascularization was noted in both the patients but the second patient elicited marked increase in vascularity on the fourth as well as the tenth day and drastic reduction in pain on day four, with no change on the tenth day. The results showed that LLLT was an effective adjunctive treatment in promoting reevascularization and pain control during early healing of free gingival graft.

  9. Quantum treatment of two-stage sub-Doppler laser cooling of magnesium atoms

    Prudnikov, O. N.; Brazhnikov, D. V.; Taichenachev, A. V.; Yudin, V. I.; Bonert, A. E.; Il'enkov, R. Ya.; Goncharov, A. N.

    2015-12-01

    Deep laser cooling of 24Mg atoms has been theoretically studied. We propose a two-stage sub-Doppler cooling strategy using electrodipole transition 3 3P2→3 3D3 (λ =383.8 nm). The first stage implies exploiting magneto-optical trap with σ+ and σ- light beams, while at the second stage lin ⊥ lin molasses is used. We focus on achieving a large number of ultracold atoms (TeffPlanck equation. The second cooling stage allows achieving sufficiently lower kinetic energies of the atomic cloud as well as increased fraction of ultracold atoms at certain conditions compared to the first one. We hope that the obtained results can help in overcoming current experimental problems in deep cooling of 24Mg atoms by means of laser field. Cold magnesium atoms cooled in a large amount to several μ K are of huge interest to, for example, quantum metrology and to other many-body cold-atoms physics.

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

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

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

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

  12. Two-component dual-scatter laser Doppler velocimeter with frequency burst signal readout.

    Brayton, D B; Kalb, H T; Crosswy, F L

    1973-06-01

    A dual-scatter laser Doppler velocimeter (LDV) system designed for measuring wind tunnel flow velocity is described. The system simultaneously measures two orthogonal velocity components of a flowing fluid at a common point in the flow. Essential single-velocity component dual-scatter concepts are presented to simplify the description of the more sophisticated two-component system. To implement the two-component system three laser beams with a 0 degrees , 45 degrees , and 90 degrees polarization plane relationship are focused to a common point in the flow by the system-transmitting optics. The beams interfere to form two perpendicular sets of interference fringe planes that are orthogonally polarized. The system-receiving optics collect and separate the orthogonally polarized components of laser radiation scattered from micron-size particles moving with the flowing fluid through the ringes. The system requires no artificial seeding, since intrinsic test section aerosols are utilized for radiation scattering. The passage of each scatter particle through the interference fringes simultaneously produces two frequency-burst-type photodetected signals, the frequencies of which are directly proportional to two perpendicular components of particle velocity. The system photodetection, signal-conditioning, and data acquisition instrumentation is specifically designed to process the frequency burst information in the time domain as opposed to spectrum analysis or frequency domain processing. The system was initially evaluated in an AEDC wind tunnel operating over a Mach number range from 0.6 to 1.5. The LDV and calculated wind tunnel mean velocity data agreed to within 1.25%; flow direction deviations of a few milliradians were resolved. PMID:20125494

  13. 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

    Roehle, I.

    1999-11-01

    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.)

  14. Microvascular involvement in systemic sclerosis: laser Doppler evaluation of reactivity to acetylcholine and sodium nitroprusside by iontophoresis

    Civita, L; Rossi, M.; Vagheggini, G; F. Storino; Credidio, L; Pasero, G; C. Giusti(INFN, Pavia); Ferri, C

    1998-01-01

    OBJECTIVES—To investigate the skin vasodilatory response to iontophoretically applied acetylcholine (Ach), an endothelium dependent vasodilator, and to sodium nitroprusside (SNP), an endothelium independent vasodilator, in patients with systemic sclerosis (SSc).
METHODS—Eleven SSc patients were preliminarily studied (10 females, mean age 40.5; mean disease duration 6.5 years), and 16 age and sex matched control subjects. By means of laser Doppler flowmetry skin blood flow was evaluated at thi...

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

    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. (paper)

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

    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.

  17. Development of a laser-Doppler system for measurement of velocity fields in PVT crystal growth systems

    Jones, O. C.; Glicksman, M. E.; Lin, J. T.; Kim, G. T.; Singh, N. B.

    1991-01-01

    A laser-Doppler velocimetry (LDV) system capable of measuring velocities as low as 10 exp -5 m/s is presented, and a calibration system for determining the accuracy of the LDV system at these velocities is described. The results obtained in mercurous chloride crystal grown in cylindrical ampoules at 300 C, using physical vapor transport (PVT) methods, are presented. It is concluded that the overall flow pattern observed is a unicellular, asymmetric pattern between Rayleigh number of 125 and 250.

  18. Self-mixing in low-noise semiconductor vortex laser: detection of a rotational Doppler shift in backscattered light.

    Seghilani, Mohamed; Myara, Mikhaël; Sagnes, Isabelle; Chomet, Baptiste; Bendoula, Ryad; Garnache, Arnaud

    2015-12-15

    Light carrying orbital angular momentum L⃗, scattered by a rotating object at angular velocity Ω⃗, experiences a rotational Doppler shift Ω⃗·L⃗. We show that this fundamental light-matter interaction can be detected exploiting self-mixing in a vortex laser under Doppler-shifted optical feedback, with quantum noise-limited light detection. We used a low-noise relaxation oscillation-free (class-A) vortex laser, based on III-V semiconductor vertical-external-cavity-surface-emitting laser technology to generate coherent Laguerre-Gauss beams carrying L=ℏl (l=±1,…±4). Linear and rotational Doppler effects were studied experimentally and theoretically. This will allow us to combine a velocity sensor with optical tweezers for micro-manipulation applications, with high performances: compact, powerful ≫10  mW, high-quality beam, auto-aligned, linear response up to >10⁸  rad/s or >300  km/h, low back-scattered light detection limit <10⁻¹⁶/Hz. PMID:26670510

  19. Reproducibility of measuring cerebral blood flow by laser-Doppler flowmetry in mice.

    Tajima, Yosuke; Takuwa, Hiroyuki; Kawaguchi, Hiroshi; Masamoto, Kazuto; Ikoma, Yoko; Seki, Chie; Taniguchi, Junko; Kanno, Iwao; Saeki, Naokatsu; Ito, Hiroshi

    2014-01-01

    Laser-Doppler flowmetry has been widely used to trace hemodynamic changes in experimental stroke research. The purpose of the present study was to evaluate the day-to-day test-retest reproducibility of measuring cerebral blood flow by LDF in awake mice. The flux indicating cerebral blood flow (CBF), red blood cell (RBC) velocity, and RBC concentration were measured with LDF via cranial windows for the bilateral somatosensory cortex in awake mice. LDF measurements were performed three times, at baseline, 1 hour after, and 7 days after the baseline measurement. Moreover, breathing rate (BR) and partial pressure of transcutaneous CO₂ (PtCO₂) were measured simultaneously with LDF measurement. Intraclass correlation coefficient (ICC) and within-subject coefficient of variation (CVw) were calculated. CBF, RBC velocity, and RBC concentration showed good day-to-day test-retest reproducibility (ICC: 0.61 - 0.95, CVw: 8.3% - 15.4%). BR and PtCO₂ in awake mice were stable during the course of the experiments. The evaluation of cerebral microcirculation using LDF appears to be applicable to long-term studies. PMID:24389142

  20. Eye-safe diode laser Doppler lidar with a MEMS beam-scanner.

    Hu, Qi; Pedersen, Christian; Rodrigo, Peter John

    2016-02-01

    We present a novel Doppler lidar that employs a cw diode laser operating at 1.5 μm and a micro-electro-mechanical-system scanning mirror (MEMS-SM). In this work, two functionalities of the lidar system are demonstrated. Firstly, we describe the capability to effectively steer the lidar probe beam to multiple optical transceivers along separate lines-of-sight. The beam steering functionality is demonstrated using four lines-of-sight - each at an angle of 18° with respect to their symmetry axis. Secondly, we demonstrate the ability to spatially dither the beam focus to reduce the mean irradiance at the probing distance (R = 60 m) of each line-of-sight - relevant for meeting eye-safety requirements. The switching time of the MEMS-SM is measured to be in the order of a few milliseconds. Time-shared (0.25 s per line-of-sight) radial wind speed measurements at 50 Hz data rate are experimentally demonstrated. Spatial dithering of the beam focus is also implemented using a spiral scan trajectory resulting in a 16 dB reduction of beam focus mean irradiance. PMID:26906770

  1. Comparison of NIRS, laser Doppler flowmetry, photoplethysmography, and pulse oximetry during vascular occlusion challenges.

    Abay, T Y; Kyriacou, P A

    2016-04-01

    Monitoring changes in blood volume, blood flow, and oxygenation in tissues is of vital importance in fields such as reconstructive surgery and trauma medicine. Near infrared spectroscopy (NIRS), laser Doppler (LDF) flowmetry, photoplethysmography (PPG), and pulse oximetry (PO) contribute to such fields due to their safe and noninvasive nature. However, the techniques have been rarely investigated simultaneously or altogether. The aim of this study was to investigate all the techniques simultaneously on healthy subjects during vascular occlusion challenges. Sensors were attached on the forearm (NIRS and LDF) and fingers (PPG and PO) of 19 healthy volunteers. Different degrees of vascular occlusion were induced by inflating a pressure cuff on the upper arm. The responses of tissue oxygenation index (NIRS), tissue haemoglobin index (NIRS), flux (LDF), perfusion index (PPG), and arterial oxygen saturation (PO) have been recorded and analyzed. Moreover, the optical densities were calculated from slow varying dc PPG, in order to distinguish changes in venous blood volumes. The indexes showed significant changes (p  <  0.05) in almost all occlusions, either venous or over-systolic occlusions. However, differentiation between venous and arterial occlusion by LDF may be challenging and the perfusion index (PI) may not be adequate to indicate venous occlusions. Optical densities may be an additional tool to detect venous occlusions by PPG. PMID:26963349

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

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

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

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

    2013-01-01

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

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

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

    2013-01-01

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

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

    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

    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.

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

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

  7. Multifractal spectra of laser Doppler flowmetry signals in healthy and sleep apnea syndrome subjects

    Buard, Benjamin; Trzepizur, Wojciech; Mahe, Guillaume; Chapeau-Blondeau, François; Rousseau, David; Gagnadoux, Frédéric; Abraham, Pierre; Humeau, Anne

    2009-07-01

    Laser Doppler flowmetry (LDF) signals give a peripheral view of the cardiovascular system. To better understand the possible modifications brought by sleep apnea syndrome (SAS) in LDF signals, we herein propose to analyze the complexity of such signals in obstructive SAS subjects, and to compare the results with those obtained in healthy subjects. SAS is a pathology that leads to a drop in the parasympathetic tone associated with an increase in the sympathetic tone in awakens SAS patients. Nine men with obstructive SAS and nine healthy men participated awaken in our study and LDF signals were recorded in the forearm. In our work, complexity of LDF signals is analyzed through the computation and analysis of their multifractal spectra. The multifractal spectra are estimated by first estimating the discrete partition function of the signals, then by determining their Renyi exponents with a linear regression, and finally by computing their Legendre transform. The results show that, at rest, obstructive SAS has no or little impact on the multifractal spectra of LDF signals recorded in the forearm. This study shows that the physiological modifications brought by obstructive SAS do not modify the complexity of LDF signals when recorded in the forearm.

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

    Cally Gill

    2013-09-01

    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.

  9. Haemodynamic responses to temperature changes of human skeletal muscle studied by laser-Doppler flowmetry

    Using a small, but very instructive experiment, it is demonstrated that laser-Doppler flowmetry (LDF) at large interoptode spacing represents a unique tool for new investigations of thermoregulatory processes modulating the blood flow of small muscle masses in humans. It is shown on five healthy subjects that steady-state values of blood flow (perfusion) in the thenar eminence muscle group depend in a complex manner on both the local intramuscular temperature and local skin temperature, while the values of blood flow parameters measured during physiological transients, such as the post-ischaemic hyperhaemic response, depend only on the intramuscular temperature. In addition, it is shown that the so-called biological zero (i.e. remaining LDF signal during arterial occlusion) is influenced not only as expected by the intramuscular temperature, but also by the skin temperature. The proposed results reveal that the skeletal muscle has unique thermoregulatory characteristics compared, for example, to human skin. These and other observations represent new findings and we hope that they will serve as a stimulus for the creation of new experimental protocols leading to better understanding of blood flow regulation. (paper)

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

    Bernjak, Alan; Stefanovska, Aneta

    2009-03-01

    The pulse transit time (PTT) of a wave over a specified distance along a blood vessel provides a simple non-invasive index that can be used for the evaluation of arterial distensibility. Current methods of measuring the PTT determine the propagation times of pulses only in the larger arteries. We have evaluated the pulse arrival time (PAT) to the capillary bed, through the microcirculation, and have investigated its relationship to the arterial PAT to a fingertip. To do so, we detected cardiac-induced pulse waves in skin microcirculation using laser Doppler flowmetry (LDF). Using the ECG as a reference, PATs to the microcirculation were measured on the four extremities of 108 healthy subjects. Simultaneously, PATs to the radial artery of the left index finger were obtained from blood pressure recordings using a piezoelectric sensor. Both PATs correlate in similar ways with heart rate and age. That to the microcirculation is shown to be sensitive to local changes in skin perfusion induced by cooling. We introduce a measure for the PTT through the microcirculation. We conclude that a combination of LDF and pressure measurements enables simultaneous characterization of the states of the macro and microvasculature. Information about the microcirculation, including an assessment of endothelial function, may be obtained from the responses to perturbations in skin perfusion, such as temperature stress or vasoactive substances. PMID:19202235

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

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

    2011-10-01

    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

  12. Modal parameter determination of a lightweight aerospace panel using laser Doppler vibrometer measurements

    de Sousa, Kleverson C.; Domingues, Allan C.; Pereira, Pedro P. de S.; Carneiro, Sergio H.; de Morais, Marcus V. G.; Fabro, Adriano T.

    2016-06-01

    The experimental determination of modal parameters, i.e. natural frequencies, mode shapes and damping ratio, are key in characterizing the dynamic behaviour of structures. Typically, such parameters are obtained from dynamic measurements using one or a set of accelerometers, for response measurements, along with force transducers from an impact hammer or an electrodynamic actuator, i.e. a shaker. However, lightweight structures, commonly applied in the aerospace industry, can be significantly affected by the added mass from accelerometers. Therefore, non-contact measurement techniques, like Laser Doppler Vibrometer (LDV), are a more suitable approach in determining the dynamic characteristics of such structures. In this article, the procedures and results of a modal test for a honeycomb sandwich panel for aerospace applications are presented and discussed. The main objectives of the test are the identification of natural frequencies and mode shapes in order to validate a numerical model, as well as the identification of the damping characteristics of the panel. A validated numerical model will be necessary for future detailed response analysis of the satellite, including vibroacoustic investigations to account for acoustic excitations encountered during launching. The numerical model using homogenised material properties is updated to fit the experimental results and very good agreement between experimental and numerically obtained natural frequencies and mode shapes.

  13. Quantum treatment of two-stage sub-Doppler laser cooling of magnesium atoms

    Brazhnikov, D V; Taichenachev, A V; Yudin, V I; Bonert, A E; Il'enkov, R Ya; Goncharov, A N

    2015-01-01

    The problem of deep laser cooling of $^{24}$Mg atoms is theoretically studied. We propose two-stage sub-Doppler cooling strategy using electro-dipole transition $3^3P_2$$\\to$$3^3D_3$ ($\\lambda$=383.9 nm). The first stage implies exploiting magneto-optical trap with $\\sigma^+$ and $\\sigma^-$ light beams, while the second one uses a lin$\\perp$lin molasses. We focus on achieving large number of ultracold atoms (T$_{eff}$ < 10 $\\mu$K) in a cold atomic cloud. The calculations have been done out of many widely used approximations and based on quantum treatment with taking full account of recoil effect. Steady-state average kinetic energies and linear momentum distributions of cold atoms are analysed for various light-field intensities and frequency detunings. The results of conducted quantum analysis have revealed noticeable differences from results of semiclassical approach based on the Fokker-Planck equation. At certain conditions the second cooling stage can provide sufficiently lower kinetic energies of atom...

  14. Acute effects of vascular modifying agents in solid tumors assessed by noninvasive laser Doppler flowmetry and near infrared spectroscopy

    Kragh, Michael; Quistorff, Bjørn; Horsman, Michael R;

    2002-01-01

    The potential of noninvasive laser Doppler flowmetry (LDF) and near infrared spectroscopy (NIRS) to detect acute effects of different vascular-modifying agents on perfusion and blood volume in tumors was evaluated. C3H mouse mammary carcinomas (approximately 200 mm(3)) in the rear foot of CDF1 mice...... LDF, using a 41 degrees C heated custom-built LDF probe with four integrated laser/receiver units, and tumor blood volume was estimated by NIRS, using light guide coupled reflectance measurements at 800+/-10 nm. FAA, DMXAA, CA4DP, and HDZ significantly decreased tumor perfusion by 50%, 47%, 73...

  15. Laser frequency stabilization and large detuning by Doppler-free dichroic lock technique: Application to atom cooling

    V B Tiwari; S R Mishra; H S Rawat; S Singh; S P Ram; S C Mehendale

    2005-09-01

    We present results of a study of frequency stabilization of a diode laser ( = 780 nm) using the Doppler-free dichroic lock (DFDL) technique and its use for laser cooling of atoms. Quantitative measurements of frequency stability were performed and the Allan variance was found to be 6.9 × 10−11 for an averaging time of 10 s. The frequency-stabilized diode laser was used to obtain the trapping beams for a magneto-optic trap (MOT) for Rb atoms. Using the DFDL technique, the laser frequency could be locked over a wide range and this enabled measurement of detuning dependence of the number and temperature of cold atoms using a relatively simple experimental set-up.

  16. Laser Doppler velocimeter measurements and laser sheet imaging in an annular combustor model. M.S. Thesis, Final Report

    Dwenger, Richard Dale

    1995-01-01

    An experimental study was conducted in annular combustor model to provide a better understanding of the flowfield. Combustor model configurations consisting of primary jets only, annular jets only, and a combination of annular and primary jets were investigated. The purpose of this research was to provide a better understanding of combustor flows and to provide a data base for comparison with computational models. The first part of this research used a laser Doppler velocimeter to measure mean velocity and statistically calculate root-mean-square velocity in two coordinate directions. From this data, one Reynolds shear stress component and a two-dimensional turbulent kinetic energy term was determined. Major features of the flowfield included recirculating flow, primary and annular jet interaction, and high turbulence. The most pronounced result from this data was the effect the primary jets had on the flowfield. The primary jets were seen to reduce flow asymmetries, create larger recirculation zones, and higher turbulence levels. The second part of this research used a technique called marker nephelometry to provide mean concentration values in the combustor. Results showed the flow to be very turbulent and unsteady. All configurations investigated were highly sensitive to alignment of the primary and annular jets in the model and inlet conditions. Any imbalance between primary jets or misalignment of the annular jets caused severe flow asymmetries.

  17. Exciting positronium with a solid-state UV laser: the Doppler-broadened Lyman-α transition

    Deller, A.; Edwards, D.; Mortensen, T.; Isaac, C. A.; van der Werf, D. P.; Telle, H. H.; Charlton, M.

    2015-09-01

    A tunable, pulsed laser was used to excite the Lyman-α transition (1S-2P) of positronium (Ps). The laser system has a large bandwidth of Δ ν =225 GHz at λ =243 nm, providing significant coverage of the Doppler-broadened, single-photon transition. The infra-red fundamental of a Nd:YAG laser was converted to ultraviolet by a series of solid-state, nonlinear processes, centred about an unseeded optical parametric oscillator, from which the bulk of the ultimate bandwidth derives. The Ps atoms were created by bombarding mesoporous silica with positrons, and the Doppler-width of the 1S-2P transition of the resulting ensemble was measured to be Δ ν =672+/- 43 GHz (equivalent to T≈ 300 K). It is envisaged that the UV laser will be incorporated into a two-step process to efficiently form Rydberg states of Ps, with potential applications in synthesis of cold antihydrogen, gravity measurements with antimatter, or for injection of electrons and positrons into a stellarator.

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

    Statham, Shannon M.

    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

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

    Reiners, A; Ulbrich, R G

    2014-01-01

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

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

    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)

  1. Non-invasive technique for assessment of vascular wall stiffness using laser Doppler vibrometry

    Campo, Adriaan; Segers, Patrick; Heuten, Hilde; Goovaerts, Inge; Ennekens, Guy; Vrints, Christiaan; Baets, Roel; Dirckx, Joris

    2014-06-01

    It has been shown that in cardiovascular risk management, stiffness of large arteries has a very good predictive value for cardiovascular disease and mortality. This parameter is best known when estimated from the pulse wave velocity (PWV) measured between the common carotid artery (CCA) in the neck and femoral artery in the groin, but may also be determined locally from short-distance measurements on a short vessel segment. In this work, we propose a novel, non-invasive, non-contact laser Doppler vibrometry (LDV) technique for evaluating PWV locally in an elastic vessel. First, the method was evaluated in a phantom setup using LDV and a reference method. Values correlated significantly between methods (R ≤ 0.973 (p ≤ 0.01)); and a Bland-Altman analysis indicated that the mean bias was reasonably small (mean bias ≤ -2.33 ms). Additionally, PWV was measured locally on the skin surface of the CCA in 14 young healthy volunteers. As a preliminary validation, PWV measured on two locations along the same artery was compared. Local PWV was found to be between 3 and 20 m s-1, which is in line with the literature (PWV = 5-13 m s-1). PWV assessed on two different locations on the same artery correlated significantly (R = 0.684 (p < 0.01)). In summary, we conclude that this new non-contact method is a promising technique to measure local vascular stiffness in a fully non-invasive way, providing new opportunities for clinical diagnosing.

  2. Analysis of Transitional and Turbulent Flow Through the FDA Benchmark Nozzle Model Using Laser Doppler Velocimetry.

    Taylor, Joshua O; Good, Bryan C; Paterno, Anthony V; Hariharan, Prasanna; Deutsch, Steven; Malinauskas, Richard A; Manning, Keefe B

    2016-09-01

    Transitional and turbulent flow through a simplified medical device model is analyzed as part of the FDA's Critical Path Initiative, designed to improve the process of bringing medical products to market. Computational predictions are often used in the development of devices and reliable in vitro data is needed to validate computational results, particularly estimations of the Reynolds stresses that could play a role in damaging blood elements. The high spatial resolution of laser Doppler velocimetry (LDV) is used to collect two component velocity data within the FDA benchmark nozzle model. Two flow conditions are used to produce flow encompassing laminar, transitional, and turbulent regimes, and viscous stresses, principal Reynolds stresses, and turbulence intensities are calculated from the measured LDV velocities. Axial velocities and viscous stresses are compared to data from a prior inter-laboratory study conducted with particle image velocimetry. Large velocity gradients are observed near the wall in the nozzle throat and in the jet shear layer located in the expansion downstream of the throat, with axial velocity changing as much as 4.5 m/s over 200 μm. Additionally, maximum Reynolds shear stresses of 1000-2000 Pa are calculated in the high shear regions, which are an order of magnitude higher than the peak viscous shear stresses (nozzle model, indicating that hemolysis may occur under certain flow conditions. As such, the presented turbulence quantities from LDV, which are also available for download at https://fdacfd.nci.nih.gov/ , provide an ideal validation test for computational simulations that seek to characterize the flow field and to predict hemolysis within the FDA nozzle geometry. PMID:27350137

  3. Vibration transmissibility on rifle shooter: A comparison between accelerometer and laser Doppler vibrometer data

    Scalise, L.; Casacanditella, L.; Santolini, C.; Martarelli, M.; Tomasini, E. P.

    2014-05-01

    The transmission of mechanical vibrations from tools to human subjects is known to be potentially dangerous for the circulatory and neurological systems. It is also known that such damages are strictly depending on the intensity and the frequency range of the vibrational signals transferred to the different anatomical districts. In this paper, very high impulsive signals, generated during a shooting by a rifle, will be studied, being such signals characterised by a very high acceleration amplitude as well as high frequency range. In this paper, it will be presented an experimental setup aimed to collect experimental data relative to the transmission of the vibration signals from the rifle to the shoulder of subject during the shooting action. In particular the transmissibility of acceleration signals, as well as of the velocity signals, between the rifle stock and the subject's back shoulder will be measured using two piezoelectric accelerometers and a single point laser Doppler vibrometer (LDV). Tests have been carried out in a shooting lab where a professional shooter has conducted the experiments, using different experimental configurations: two different types of stocks and two kinds of bullets with different weights were considered. Two uniaxial accelerometers were fixed on the stock of the weapon and on the back of the shoulder of the shooter respectively. Vibration from the back shoulder was also measured by means of a LDV simultaneously. A comparison of the measured results will be presented and the pros and cons of the use of contact and non-contact transducers will be discussed taking into account the possible sources of the measurement uncertainty as unwanted sensor vibrations for the accelerometer.

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

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

  5. Linking water surface roughness to velocity patterns using terrestrial laser scanning and acoustic doppler velocimetry

    Heritage, George; Milan, David; Entwistle, Neil

    2010-05-01

    There are well established links between water surface characteristics and hydraulics. Biotope identification is currently an important part of the River Habitat Survey in England and Wales. Their differentiation is based upon recognition of a family of flow features exhibited on the water surface. Variability in this water surface ‘roughness' is dependent upon the interaction of flow with boundary roughness and flow depth. Past research that has attempted to differentiate biotopes based upon differences in Froude number (Fr) and Reynolds number (Re), however this linkage has only been limited to local analysis between flow velocity, depth and roughness. Milan et al. (2010) have recently demonstrated that terrestrial laser scanning (TLS) can be applied to produce fully quantitative maps of hydraulic habitat, based upon defined water surface roughness delimeters. However the nature of the linkages between water surface roughness, flow velocity and depth are still poorly understood, particularly at the reach-scale. This study attempts to provide a full spatial picture of the links between water surface roughness, flow depth and velocity. A Sontek Acoustic Doppler Velocity Profiler (ADVP) was used to provide detailed information on vertical velocity and water depth for a 300 m reach of the gravel-bed River Wharfe, Yorkshire, UK. Simultaneous to the ADVP measurements, a Riegl LMS-Z210 TLS was used to take a series of first return scans of the water surface. Categorisation of the point cloud elevation data for the water surface was achieved through the allocation of moving window standard deviation values to a regular grid, thus defining water surface roughness. The ADVP data demonstrate gross reach-scale variation in velocity and depth linked to bedforms, and more localised spatial and temporal variation within biotope units. The ADVP data was used to produce reach-scale maps of Fr and Re. The extent to which water surface roughness defined biotopes mapped onto these

  6. Acoustic flowmeters: Their applications in hydraulics

    Nitzsche, Ulf

    Flowmeter installations for viscous and high hydrostatic pressure media are developed. Their usability is considered for characteristic measuring tasks in the field of oil hydraulics. The properties of flow sensors are evaluated by system analysis. Acoustic measuring systems are preferred. Two ultrasonic flowmeters are realized. Simulation models, installation with piezoceramic material parameters, and sound visualization support these developments. A computer aided hydraulic test stand is developed in order to detect the measuring characteristics of this system. Flowmeter applications are shown using the identification of the static and dynamic parameters of an electrohydraulic pilot valve.

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

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

    2014-04-15

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

  8. Smart ultrasonic flowmeter used for the operation support of water resource management in the agricultural areas

    Elmostafa, Ziani; Mustapha, Bennouna; Boissier, Raymond

    2008-10-01

    Ultrasonic sensors transmit acoustic waves and receive them later. This is done by ultrasonic transducers, which transform an ultrasonic wave into an electrical signal and vice versa. Often, it is possible to use the same transducer for both transmitting and receiving. The most important parts of any ultrasonic sensor are the transducers. The spectral and spatial radiation characteristics of these components are the prime determinants of sensor performance. Such transducers must have a robust design, stable radiation pattern (high directivity) and good receiving sensitivity. Intelligent ultrasonic sensors have the possibility to extract the information about the variables to be measured, carried by the ultrasonic signals efficiently and with accuracy. To achieve this performance, the signals are processed by dedicated hardware (accurate electronic measuring devices). Ultrasound has the property, that its velocity is strongly affected by the flow velocity of the fluids in which it propagates. The ultrasonic flowmeters have gained a lot of attention over the past few years; they have several advantages over the differential pressure flowmeter, turbine meters, coriolis meters and vortex meters. They are widely used to measure the flow of liquids, first, they are either less intrusive (wetted flowmeter) or non-intrusive (clamp-on flowmeter), depending on the model. Also, they don't have moving parts that are subject to wear over time, and with minimum obstruction of the flow. Ultrasonic flowmeter are not limited to clean liquids (Transit time flowmeter), a special type of ultrasonic flowmeter can also accurately measure the flow of slurries and liquids with many impurities (Doppler flowmeter). This part of paper describes the intelligent ultrasonic sensor. The conception or the realization of intelligent ultrasonic sensor requires the synthesis of several technologies, a knowledge in the fields of sensor, digital ultrasonic signal processing, distributed system and

  9. Experiments on the inhibition of mixing in stably stratified decaying turbulence using laser Doppler anemometry and laser-induced fluorescence

    Barrett, T. K.; Van Atta, C. W.

    1991-05-01

    The decay of velocity and density fluctuations in buoyancy influenced turbulence generated by a biplanar grid, towed horizontally through a stably stratified fluid with uniform optical index of refraction was measured for three different constant density gradients. Experiments were performed in a closed rectangular test section. Fluid velocities were measured with a laser Doppler anemometer. Density was measured by adding a fluorescent dye (Rhodamine 6G) to the working fluid in such a way that the light fluoresced by the dye when excited by a laser was proportional to the local density of the solution. Simultaneous single-point measurements of the vertical velocity, the horizontal velocity in the direction of grid motion, and the density were obtained at a fixed point in the center of the test section. Statistical moments representing the state of the turbulent flow field at different periods of the decay were computed by ensemble averaging data from 100 tows with similar initial conditions. Density profiles of the quiescent fluid, before and after the grid was towed through the test section, were measured, and estimates of the total mixing accomplished by a single sweep of the grid through the fluid were calculated. The measured internal Richardson number Rii={- (1)/(2) [gρ'2/(∂ρ¯/∂z)]} ×(1/ (1)/(2) ρ¯) indicates that, immediately behind the grid, the turbulence was unaffected by the stable stratifications. At a time depending on the strength of the mean density gradient, the buoyancy forces acting on the turbulent eddies become as large as the inertial forces and have significant effects on the final stages of the decay of the turbulent flow field. Measurements of the convective mass flux indicate that the vertical transport of mass due to turbulence was significantly reduced by buoyancy forces. This was confirmed by integral estimates of the mixing, which indicate that the ability of the turbulent eddies to homogenize the stratified fluid decreases

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

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

    1987-10-01

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

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

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

    2014-05-27

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

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

    Eduardo Tibiriçá

    2011-01-01

    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

  13. Simple helium flowmeter for dilution refrigerators

    Niinikoski, T O

    1972-01-01

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

  14. Effect of clenbuterol on cardiopulmonary parameters and intramuscular blood flow by laser Doppler flowmetry in anesthetized ponies

    Lee, Yong H.; Clarke, Kathleen W.; Alibhai, Hatim I. K.

    1994-09-01

    The cardiopulmonary affects and the affects on muscular microperfusion of the beta adrenergic agonist, clenbuterol (0.8 mcg/kg intravenously), were investigated in dorsally recumbent anesthetized ponies. Muscle microcirculation was measured by laser Doppler flowmetry, utilizing fine optical fiber probes. Other measurements included heart rate, cardiac output, arterial blood pressure, and arterial blood gas tensions. Clenbuterol injection caused a regular, but transitory rise in muscle microcirculation, an increase in heart rate, and cardiac output and a decrease in mean arterial blood pressure. Clenbuterol did appear to prevent the continuing fall in arterial blood oxygen tensions seen in the treatment groups, but had only minimal affects in reversing the hypoxia already present.

  15. Design of a Geothermal Downhole Magnetic Flowmeter

    Glowka, Dave A.; Normann, Randy A.

    2015-06-15

    This paper covers the development of a 300°C geothermal solid-state magnetic flowmeter (or magmeter) to support in situ monitoring of future EGS (enhanced geothermal system) production wells. Existing flowmeters are simple mechanical spinner sensors. These mechanical sensors fail within as little as 10 hrs, while a solid-state magmeter has the potential for months/years of operation. The design and testing of a magnetic flow sensor for use with existing high-temperature electronics is presented.

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

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

    2014-05-01

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

  17. Effect of Stress and Saturation on Shear Wave Anisotropy: Laboratory Observations Using Laser Doppler Interferometry

    Lebedev, M.; Collet, O.; Bona, A.; Gurevich, B.

    2015-12-01

    Estimations of hydrocarbon and water resources as well as reservoir management during production are the main challenges facing the resource recovery industry nowadays. The recently discovered reservoirs are not only deep but they are also located in complicated geological formations. Hence, the effect of anisotropy on reservoir imaging becomes significant. Shear wave (S-wave) splitting has been observed in the field and laboratory experiments for decades. Despite the fact that S-wave splitting is widely used for evaluation of subsurface anisotropy, the effects of stresses as well fluid saturation on anisotropy have not been understood in detail. In this paper we present the laboratory study of the effect of stress and saturation on S-wave splitting for a Bentheim sandstone sample. The cubic sample (50mm3), porosity 22%, density 1890kg/m3) was placed into a true-triaxial cell. The sample was subjected to several combinations of stresses varying from 0 to 10MPa and applied to the sample in two directions (X and Y), while no stress was applied to the sample in the Z-direction. The sample's bedding was nearly oriented parallel to Y-Z plane. The ultrasonic S-waves were exited at a frequency of 0.5MHz by a piezoelectric transducer and were propagating in the Z-direction. Upon wave arrival onto the free surface the displacement of the surface was monitored by a Laser Doppler interferometer. Hodograms of the central point of the dry sample (Fig. 1) demonstrate how S-wave polarizations for both "fast" and "slow" S-waves change when increasing the stress in the X direction, while the stress in direction Y is kept constant at 3 MPa. Polarization of the fast S wave is shifted towards the X-axis (axis of the maximum stress). While both S-wave velocities increase with stress, the anisotropy level remains the same. No shift of polarization of fast wave was observed when the stress along the Y-axis was kept at 3 MPa, while the stress along the X-axis was increasing. However, in

  18. Assessment of speed distribution of red blood cells in the microvascular network in healthy volunteers and type 1 diabetes using laser Doppler spectra decomposition

    We applied a recently reported method of decomposition of laser Doppler power density spectra for in vivo monitoring of speed distributions of red blood cells (RBCs) in the microvascular network. The spectrum decomposition technique allows us to derive the distribution of RBC speed (in absolute units (mm s−1)) versus RBC concentration (in arbitrary units). We carried out postocclusive reactive hyperaemia (PORH) test in 15 healthy volunteers and 21 diabetic patients in which the duration of type 1 diabetes was longer than 10 years. Measurements were carried out simultaneously with the use of a typical laser Doppler commercial instrument and speed resolved laser Doppler instrument utilizing the new technique based on decomposition of the laser Doppler spectra. We show that for the classical laser Doppler instrument, none of the PORH parameters revealed a statistical significance of difference between the groups analyzed. In contrast, the RBC speed distributions obtained from laser Doppler spectra during rest in the control group and type 1 diabetes are statistically significant. This result suggests that speed distribution measurements in the rest state (without any kind of stimulation test) allows for the assessment of microcirculation disorders. Measurements carried out in healthy subjects show that the first moment of speed distributions (mean speed of the distributions) is 2.32 ± 0.54 mm s−1 and 2.57 ± 0.41 mm s−1 for optodes located on the toe and finger of the hand, respectively. Respective values in type 1 diabetes were higher: 3.00 ± 0.36 mm s−1 and 3.10 ± 0.48 mm s−1. (paper)

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

    Litz, C. J., Jr.

    1994-09-01

    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.

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

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

  1. Sub-Doppler direct infrared laser absorption spectroscopy in fast ion beams: The fluorine hyperfine structure of HF +

    Coe, J. V.; Owrutsky, J. C.; Keim, E. R.; Agman, N. V.; Hovde, D. C.; Saykally, R. J.

    1989-04-01

    We report the development of a new general technique for measuring vibration-rotation spectra of molecular ions with sub-Doppler resolution and with accurate determination of the mass and number density of the carriers of all spectral features. With this method, called direct laser absorption spectroscopy in fast ion beams (DLASFIB), we have carried out the first observation of direct absorption of photons by ions in a fast ion beam. Hyperfine-resolved vibration-rotation transitions of HF+ have been measured, and along with optical combination differences and laser magnetic resonance data, have been analyzed to yield the fluorine hyperfine parameters a, b, c and d for both v=0 and v=1 in the X 2Π state. Comparisons with many-body perturbation theory results are presented.

  2. Sub-Doppler direct infrared laser absorption spectroscopy in fast ion beams: The fluorine hyperfine structure of HF/sup +/

    Coe, J.V.; Owrutsky, J.C.; Keim, E.R.; Agman, N.V.; Hovde, D.C.; Saykally, R.J.

    1989-04-15

    We report the development of a new general technique for measuring vibration--rotation spectra of molecular ions with sub-Doppler resolution and with accurate determination of the mass and number density of the carriers of all spectral features. With this method, called direct laser absorption spectroscopy in fast ion beams (DLASFIB), we have carried out the first observation of direct absorption of photons by ions in a fast ion beam. Hyperfine-resolved vibration--rotation transitions of HF/sup +/ have been measured, and along with optical combination differences and laser magnetic resonance data, have been analyzed to yield the fluorine hyperfine parameters a, b, c and d for both v = 0 and v = 1 in the X /sup 2/Pi state. Comparisons with many-body perturbation theory results are presented.

  3. Sub-Doppler direct infrared laser absorption spectroscopy in fast ion beams: The fluorine hyperfine structure of HF+

    We report the development of a new general technique for measuring vibration--rotation spectra of molecular ions with sub-Doppler resolution and with accurate determination of the mass and number density of the carriers of all spectral features. With this method, called direct laser absorption spectroscopy in fast ion beams (DLASFIB), we have carried out the first observation of direct absorption of photons by ions in a fast ion beam. Hyperfine-resolved vibration--rotation transitions of HF+ have been measured, and along with optical combination differences and laser magnetic resonance data, have been analyzed to yield the fluorine hyperfine parameters a, b, c and d for both v = 0 and v = 1 in the X 2Pi state. Comparisons with many-body perturbation theory results are presented

  4. Design and evaluation of a short coherence length laser-based Doppler wind Lidar system for wind energy applications

    Shinohara, Leilei; Asche-Tauscher, Julian; Fox, Maik; Beuth, Thorsten; Stork, Wilhelm

    2014-05-01

    Nowadays larger horizontal axis wind turbines (HAWT) are setup in difficult to access locations adding an overhead to the production cost as well as the Operation & Maintenance (O&M) costs. In order to cover those overhead cost, Lidar assisted preview control of wind turbine blade pitch system is prosperous both on research and industry applications. However, there are not a lot of choices to remote sense the wind field inflow. Doppler wind Lidar systems have been proved to be advantageous on such applications. However due to the economical consideration, the state-of-the-art wind Lidar systems are only limited on research. Therefore, developing a cost efficient wind Lidar to support the pitch control of HAWT to reduce the material requirement, lower the O&M cost and decrease the cost of energy (COE) in the long term is our motivation. Our current main focusing of investigations has been laid on the optical design of emitting and receiving system, and the evaluation of the low cost laser system instead of using a high cost fiber laser as a transmitter. The short coherence length lasers brings a higher phase noise into the detection, normally it is not used for the coherent Lidars system. However, such a laser can achieve a higher output power with a low cost which is very important for the market. In order to bring such kind of laser into the application, different sending, receiving, and detection design is simulated and tested. Those testing results are presented in this paper.

  5. [The value of laser Doppler examination of differential diagnosis of the Sudeck syndrome with local osteoporosis after tibia fracture].

    Grys, Grzegorz; Orłowski, Jan; Pomianowski, Stanisław; Sawicki, Grzegorz

    2003-01-01

    The fractures of the shaft of the tibia were analyzed in 120 cases. The level of the osteoporosis in the radiological examination was assessed in comparison to the healthy limb. Osteoporosis was recorded in 60.6% of the cases. The clinical symptoms of the Sudeck syndrome was recorded in 11.25% of the cases. The Laser-Doppler examination was carried out in 120 cases. A standard 3 points measurement was employed: the apex of the toe, the flexion-dorsal part of the foot, and the medial part of the mid tibia length. The examination was done comparatively on both limbs. The pressure used in the occlusion, was 100 mm Hg higher than the pressure on the humeral artery. A faster and higher amplitude post-occlusion circulation reaction in the affected limb, among the patients with an early stage of the clinically diagnosed Sudeck syndrome had been recorded. The outcome is significant statistically. The Laser-Doppler measurement of the microcirculation is a new method and definite conclusions must be draw with caution. However, these results encourage further research. PMID:15052726

  6. Differential doppler heterodyning technique

    Lading, Lars

    1971-01-01

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

  7. A comparison between 133Xenon washout technique and Laser Doppler flowmetry in the measurement of local vasoconstrictor effects on the microcirculation in subcutaneous tissue and skin

    Kastrup, J; Bülow, J; Lassen, N A

    1987-01-01

    Changes in skin blood flow measured by Laser Doppler flowmetry and changes in subcutaneous blood flow measured by 133Xenon washout technique were compared during activation of the local sympathetic mediated veno-arteriolar vasoconstrictor reflex by lowering the area of investigation below heart...... forearm, and on the calf with preserved sympathetic nerve supply. The Laser Doppler method registered a 23% reduction in skin blood flow during lowering of the extremities independently of the sympathetic nerve supply to the skin. The 133Xenon method recorded a 44% decrease in blood flow in innervated and...

  8. Glucagon-like peptide-2 stimulates mucosal microcirculation measured by laser Doppler flowmetry in end-jejunostomy short bowel syndrome patients

    Høyerup, P; Hellström, P M; Schmidt, P T;

    2013-01-01

    In animal and human studies glucagon-like peptide-2 (GLP-2) has been shown to increase blood flow in the superior mesenteric artery and the portal vein. This study describes the effect of GLP-2 measured directly on the intestinal mucosal blood flow by laser Doppler flowmetry (LDF) in end-jejunost......In animal and human studies glucagon-like peptide-2 (GLP-2) has been shown to increase blood flow in the superior mesenteric artery and the portal vein. This study describes the effect of GLP-2 measured directly on the intestinal mucosal blood flow by laser Doppler flowmetry (LDF) in end...

  9. A mobile incoherent Mie-Rayleigh Doppler wind lidar with a single frequency and tunable operation of an injection Nd︰YAG laser

    LIU; Zhishen; (刘智深); WU; Dong; (吴; 东); ZHANG; Kailin; (张凯临); LIU; Jintao; (刘金涛); Johnathan; W.; Hair; Chiao-Yao; She

    2003-01-01

    A mobile incoherent Doppler lidar system has been experimentally demonstrated to be able to transmit reliable single frequency operation laser pulse, even after truck transit and in very high vibration environments. The linewidth of the injection-seeded pulse Nd:YAG laser can be measured by means of an I2 molecular filter. And, lidar validation experiments demonstrated the feasibility and capability of measuring wind field by the Mie-Rayleigh Doppler wind lidar. The uncertainty of measured wind speed is 0.985m/s in the altitude range from 2 to 4 km.

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

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

    2012-05-07

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

  11. Coriolis-type mass flowmeter

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

  12. Development and testing of a risk reduction high energy laser transmitter for high spectral resolution lidar and Doppler winds lidar

    Wang, Jinxue; Leyva, Victor; Hovis, Floyd E.

    2007-09-01

    Spaceborne 3-dimensional winds lidar and spaceborne High Spectral Resolution Lidar (HSRL) for aerosol and clouds are among the high priority future space missions recommended by the recent National Research Council (NRC) Decadal Review. They are expected to provide the important three dimensional winds data and aerosol data critically needed to improve climate models and numerical weather forecasting. HSRL and winds lidar have a common requirement for high energy solid-state lasers with output wavelengths at 1064nm, 532nm and 355nm, which can be achieved with Nd:YAG lasers and 2nd and 3rd harmonic generations. For direct detection winds lidar, only the 355nm output is needed. One of the key development needs is the demonstration of laser transmitter subsystem. Top issues include power and thermal management, lifetime, high energy UV operations, damage and contamination. Raytheon and its partner, Fibertek, have designed and built a space-qualifiable high energy Nd:YAG laser transmitter with funding from Raytheon Internal Research and Development (IR&D). It is intended to serve as a risk-reduction engineering unit and a test bed for the spaceborne HRSL and direct-detection Doppler winds Lidar missions. Close to 900 mJ/pulse at1064nm and a wall-plug efficiency of 6.5% have been achieved with our risk reduction laser. It is currently being characterized and tested at Raytheon Space and Airborne Systems. In this paper, we will discuss the design, build and testing results of this risk reduction high energy laser transmitter.

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

    Pape Sarah A

    2009-02-01

    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

  14. Instrument-independent flux units for laser Doppler perfusion monitoring assessed in a multi-device study on the renal cortex.

    Petoukhova, A L; Steenbergen, W; Morales, F; Graaff, R; de Jong, E D; Elstrodt, J M; de Mul, F F M; Rakhorst, G

    2003-09-01

    To investigate the feasibility of instrument-independent perfusion units for laser Doppler flowmetry, a comparison was performed of two commercial fiberoptic laser Doppler perfusion monitors measuring the same flux situation for two different types of probes. In vivo measurements were performed on the cortex of pig's kidney, with an ultrasonic arterial flow meter as reference. The flow was mainly varied by internal arterial constriction using a balloon catheter. For each probe, instruments are compared in terms of the ratio of laser Doppler flux and arterial flow. For a given probe, the flux-to-flow ratios of the two instruments show a linear mutual relationship for a wide variety of arterial flows and laser Doppler fluxes. In vitro measurements were performed on an aqueous suspension of polystyrene microspheres. For the probe with interfiber distance 500 microm the ratio of the in vivo fluxes appears to agree within 16% to the value found in vitro, while for the 250-microm probe a difference of 28% was found. For a wide range of fluxes, the in vivo flux values of one instrument can be translated into flux values for the other instrument, in spite of the instrumental differences. This enables the user to render experimental results independent of the specific instrument, thus facilitating multi-center studies. PMID:12935766

  15. Low-Power CMOS Laser Doppler Imaging Using Non-CDS Pixel Readout and 13.6-bit SAR ADC.

    Chen, Denis Guangyin; Law, Man-Kay; Lian, Yong; Bermak, Amine

    2016-02-01

    Laser Doppler imaging (LDI) measures particle flows such as blood perfusion by sensing their Doppler shift. This paper is the first of its kind in analyzing the effect of circuit noise on LDI precision which is distinctively different from conventional imaging. Based on this result, it presents a non-correlated-double-sampling (non-CDS) pixel readout scheme along with a high-resolution successive-approximation-register (SAR) analog-to-digital-converter (ADC) with 13.6b effective resolution (ER). Measurement results from the prototype chip in 0.18 μm technology confirm the theoretical analysis and show that the two techniques improve LDI sensing precision by 6.9 dB and 4.4 dB (compared to a 10b ADC) respectively without analog pre-amplification. The sensor's ADC occupies 518 μm×84 μm and is suitable for fast column parallel readout. Its differential non-linearity (DNL), integral non-linearity (INL), and input referred noise are +3.0/-2.8 LSB, +24/-17 LSB, and 110 μVrms respectively, leading to a Figure-of-Merit (FoM) of 23 fJ/state which makes it one of the most energy efficient image sensor ADCs and an order of magnitude better than the best reported LDI system using commercial high-speed image sensors. PMID:25532189

  16. Self-mixing detection of backscattered radiation in a single-mode erbium fibre laser for Doppler spectroscopy and velocity measurements

    We report an experimental study of the self-mixing effect in a single-mode multifrequency erbium fibre laser when radiation backscattered from an external moving object arrives at its cavity. To eliminate resulting chaotic pulsations in the laser, we have proposed a technique for suppressing backscattered radiation through the use of multimode fibre for radiation delivery. The multifrequency operation of the laser has been shown to lead to strong fluctuations of the amplitude of the Doppler signal and a nonmonotonic variation of the amplitude with distance to the scattering object. In spite of these features, the self-mixing signal was detected with a high signal-to-noise ratio (above 102) when the radiation was scattered by a rotating disc, and the Doppler frequency shift, evaluated as the centroid of its spectrum, had high stability (0.15%) and linearity relative to the rotation rate. We conclude that the self-mixing effect in this type of fibre laser can be used for measuring the velocity of scattering objects and in Doppler spectroscopy for monitoring the laser evaporation of materials and biological tissues. (control of laser radiation parameters)

  17. Effect of swimming training on neural microcirculation in rats with sciatic nerve compression A study based on laser Doppler flowmetry

    Yueming Gao; Xinglin Wang; Senyang Lang; Lining Zhang; Wei Suo; Tianyu Jiang; Jingping Fan

    2010-01-01

    Microcirculation of the peripheral nerve is necessary for neural growth and regeneration.However,technical limitations have limited studies in this area.The few studies conducted have concerned active exercise effects on microcirculation of the peripheral nerve.Using an animal experiment,this study evaluated the effect of swimming training on microcirculation of injured peripheral nerve by laser Doppler flowmetry.The results showed that the blood vessel at the distal end of the peripheral nerve was the main blood supply for the nerve,and the internal blood supply for the nerve had strong compensatory ability.Swimming training promoted the functional recovery of rats with sciatic nerve injury and the regeneration of myelin sheath and blood vessels,but had no impact on neural blood flow.

  18. Performance of eddy-viscosity turbulence models for predicting swirling pipe-flow: Simulations and laser-Doppler velocimetry

    Díaz, Diego del Olmo

    2015-01-01

    We use laser-Doppler velocimetry (LDV) experiments and Reynolds-averaged Navier--Stokes (RANS) simulations to study the characteristic flow patterns downstream of a standardized clockwise swirl disturbance generator. After quantifying the impact of the mesh size, we evaluate the potential of various eddy-viscosity turbulence models in providing reasonable approximations with respect to the experimental reference. Our results suggest that models from the $k$-$\\epsilon$ family are more accurate in predicting swirling flows than models from the $k$-$\\omega$ family. For sufficiently resolved meshes, the realizable $k$-$\\epsilon$ model provides the most accurate approximation of the velocity magnitudes, although it fails to capture small-scale flow structures which are accurately predicted by the standard $k$-$\\epsilon$ model and the RNG $k$-$\\epsilon$ model. Throughout the article, we highlight practical guidance for the choice of RANS turbulence models for swirling flow.

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

    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)

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

    Minnie Au

    2012-12-01

    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.

  1. Assessment of the Effects of Low-Level Laser Therapy on the Thyroid Vascularization of Patients with Autoimmune Hypothyroidism by Color Doppler Ultrasound

    Höfling, Danilo Bianchini; Chavantes, Maria Cristina; Juliano, Adriana G.; Cerri, Giovanni G.; Knobel, Meyer; Yoshimura, Elisabeth M.; Chammas, Maria Cristina

    2012-01-01

    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. PMID:23316383

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

    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 < 0.001), and the P2/P1 ratio decreased by a factor of 2 (p < 0.001), compared to the control area. After thermal stimulation, there was no change in p, P2 or P3. Conclusion. -Although a hypo-vascularization is frequently found in late sequelae of RT, we observed an increase of the cutaneous microcirculation associated with a maladjustment of the endothelial response to a thermal stimulation. These observations seem to reflect the presence of dilated new capillaries of the telangiectatic type, which are macroscopically undetectable. (authors)

  3. Contribution of laser Doppler flowmetry with venoarteriolar reflex, cold, and rewarming testing, and intravital capillaroscopy to diagnose Raynaud's phenomenon

    Zeman J

    2014-05-01

    Full Text Available Jan Zeman,1 Oksana Turyanytsya,1 Vojtĕch Kapsa,2 Mojmír Eliáš3 1Department of Clinical Cardiology and Angiology, Hospital Bulovka, 2Charles University in Prague, Faculty of Mathematics and Physics, 3Kooperativa a.s., Pobrezni, Prague, Czech Republic Background: The early differential diagnosis of Raynaud’s phenomenon (RP is crucial for the prognosis and therapy of these patients. In our microcirculatory laboratory, we use intravital capillaroscopy (IC, plethysmography (P, and laser Doppler flowmetry (LDF for examining acrosyndromes. We combine LDF with venoarteriolar reflex test, cold test, and rewarming test to achieve more reliable diagnoses of acrosyndromes. Patients and methods: We examined LDF and IC according to a strict protocol using a battery of tests (venoarteriolar reflex test, cold test, rewarming test applied to five different groups of people and compared their results: healthy controls, primary Raynaud’s phenomenon (PRP, systemic scleroderma, vibration white finger, and peripheral artery occlusive disease. Our tests included 340 individuals (72 patients plus 268 controls. Results: Although all tests provided some differences between controls and patients, only the rewarming test offered significant results for differential diagnoses. Conclusion: IC and LDF combined with the battery of tests (venoarteriolar reflex test, cold test, rewarming test under standard conditions can be used as reliable tools to distinguish between PRP and some types of secondary RP (especially in the case of systemic scleroderma, vibration white fingers, or peripheral artery occlusive disease; RPs with organic occlusions of the small arteries causing the diseases. Our methodology can help to distinguish between other types of RP, as well. Keywords: Raynaud’s phenomenon, acrosyndrome, laser Doppler flowmetry, intravital capillaroscopy, scleroderma, vibration white finger, peripheral artery occlusive disease

  4. Time-resolved and doppler-reduced laser spectroscopy on atoms

    Radiative lifetimes have been studied in neutral boron, carbon, silicon and strontium, in singly ionized gadolinium and tantalum and in molecular carbon monoxide and C2. The time-resolved techniques were based either on pulsed lasers or pulse-modulated CW lasers. Several techniques have been utilized for the production of free atoms and ions such as evaporation into an atomic beam, sputtering in hollow cathodes and laser-produced plasmas. Hyperfine interactions in boron, copper and strontium have been examined using quantum beat spectroscopy, saturation spectroscopy and collimated atomic beam spectroscopy. Measurement techniques based on effusive hollow cathodes as well as laser produced plasmas in atomic physics have been developed. Investigations on laser produced plasmas using two colour beam deflection tomography for determination of electron densities have been performed. Finally, new possibilities for view-time-expansion in light-in-flight holography using mode-locked CW lasers have been demonstrated. (au)

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

    Rodrigo, Peter John; Pedersen, Christian

    2012-01-01

    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)....

  6. 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

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

    1996-05-01

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

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

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

  8. Investigation of a laser Doppler velocimeter system to measure the flow field around a large scale V/STOL aircraft in ground effect

    Zalay, A. D.; Brashears, M. R.; Jordan, A. J.; Shrider, K. R.; Vought, C. D.

    1979-01-01

    The flow field measured around a hovering 70 percent scale vertical takeoff and landing (V/STOL) aircraft model is described. The velocity measurements were conducted with a ground based laser Doppler velocimeter. The remote sensing instrumentation and experimental tests of the velocity surveys are discussed. The distribution of vertical velocity in the fan jet and fountain; the radial velocity in the wall jet and the horizontal velocity along the aircraft underside are presented for different engine rpms and aircraft height above ground. Results show that it is feasible to use a mobile laser Doppler velocimeter to measure the flow field generated by a large scale V/STOL aircraft operating in ground effect.

  9. Investigation of a laser Doppler velocimeter system to measure the flow field of a large scale V/STOL aircraft in ground effect

    Zalay, A. D.; Brashears, M. R.; Jordan, A. J.; Shrider, K. R.; Vought, C. D.

    1979-01-01

    An experimental research program for measuring the flow field around a 70 percent scale V/STOL aircraft model in ground effect is described. The velocity measurements were conducted with a ground-based laser Doppler velocimeter at an outdoor test pad. The remote sensing instrumentation, experimental tests, and results of the velocity surveys are discussed. The distribution of vertical velocity in the fan jet and fountain, the radial velocity in the wall jet and the horizontal velocity along the aircraft underside are presented for different engine rpms and aircraft heights above ground. The study shows that it is feasible to use a mobile laser Doppler velocimeter to measure the flow field generated by a large scale V/STOL aircraft operating in ground effect.

  10. 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

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

    1997-05-27

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

  11. Monitoring Hypoxia Induced Changes in Cochlear Blood Flow and Hemoglobin Concentration Using a Combined Dual-Wavelength Laser Speckle Contrast Imaging and Doppler Optical Microangiography System

    Reif, Roberto; Qin, Jia; Shi, Lei; Dziennis, Suzan; Zhi, Zhongwei; Nuttall, Alfred L.; Wang, Ruikang K.

    2012-01-01

    A synchronized dual-wavelength laser speckle contrast imaging (DWLSCI) system and a Doppler optical microangiography (DOMAG) system was developed to determine several ischemic parameters in the cochlea due to a systemic hypoxic challenge. DWLSCI can obtain two-dimensional data, and was used to determine the relative changes in cochlear blood flow, and change in the concentrations of oxyhemoglobin (HbO), deoxyhemoglobin (Hb) and total hemoglobin (HbT) in mice. DOMAG can obtain three-dimensiona...

  12. A study of air-coupled ultrasonic flowmeter

    A non-contact flowmeter employing air-coupled ultrasonic is developed in this study. Flow rate of feed water and cooling water for the condenser are monitored to control the thermal output of the nuclear reactor. Ultrasonic flowmeter has an advantage in its accuracy compared with differential pressure flowmeter and venturi flowmeter. However, the performance of sensors decreases in high-temperature conditions such as nuclear power plants and thermal power plants, and measuring accuracy declines because a sensor lose a piezoelectricity over its Curie point. (author)

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

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

  14. O2C Laser Doppler and Digital Photo Analysis for Treatment Evaluation of Beta-Glucan versus Provitamin Pantothenic Acid of Facial Burns.

    Thieme, Daniel; Spilker, Gerald; Lefering, Rolf; Weinand, Christian

    2016-04-01

    Various creams are available for superficial second-degree burns (SSDB) of the face. We evaluated provitamin pantothenic acid versus β-glucan for SSDB of the face using the O2C laser Doppler system and digital photo analysis. Out of 20 patients (January to December 2012) with facial burns, 7 with SSDB of both cheeks were included to our study. Burned cheek wounds were treated using pantothenic acid or β-glucan. Digital photos of marked regions were taken daily from predefined distances. Microcirculation was measured at marked regions for 7 days at scheduled time points using the O2C laser Doppler. Data were evaluated using the SPSS program (SPSS Inc., Chicago, IL). Wounds treated with β-glucan showed faster reepithelialization. O2C laser Doppler measurements showed faster increase in SO2, microvascular perfusion, hemoglobin content, and blood flow. This correlated good with clinical Vancouver Scar Scale results. Although not statistically significant, β-glucan cream therapy of SSDB results in aesthetically superior outcome and faster reepithelialization. PMID:27097145

  15. Time dependent Doppler shifts in high-order harmonic generation in intense laser interactions with solid density plasma and frequency chirped pulses

    Welch, E. C.; Zhang, P.; He, Z.-H. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Dollar, F. [JILA, University of Colorado, Boulder, Colorado 80309 (United States); Krushelnick, K.; Thomas, A. G. R., E-mail: agrt@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States)

    2015-05-15

    High order harmonic generation from solid targets is a compelling route to generating intense attosecond or even zeptosecond pulses. However, the effects of ion motion on the generation of harmonics have only recently started to be considered. Here, we study the effects of ion motion in harmonics production at ultrahigh laser intensities interacting with solid density plasma. Using particle-in-cell simulations, we find that there is an optimum density for harmonic production that depends on laser intensity, which scales linearly with a{sub 0} with no ion motion but with a reduced scaling if ion motion is included. We derive a scaling for this optimum density with ion motion and also find that the background ion motion induces Doppler red-shifts in the harmonic structures of the reflected pulse. The temporal structure of the Doppler shifts is correlated to the envelope of the incident laser pulse. We demonstrate that by introducing a frequency chirp in the incident pulse we are able to eliminate these Doppler shifts almost completely.

  16. Time dependent Doppler shifts in high-order harmonic generation in intense laser interactions with solid density plasma and frequency chirped pulses

    High order harmonic generation from solid targets is a compelling route to generating intense attosecond or even zeptosecond pulses. However, the effects of ion motion on the generation of harmonics have only recently started to be considered. Here, we study the effects of ion motion in harmonics production at ultrahigh laser intensities interacting with solid density plasma. Using particle-in-cell simulations, we find that there is an optimum density for harmonic production that depends on laser intensity, which scales linearly with a0 with no ion motion but with a reduced scaling if ion motion is included. We derive a scaling for this optimum density with ion motion and also find that the background ion motion induces Doppler red-shifts in the harmonic structures of the reflected pulse. The temporal structure of the Doppler shifts is correlated to the envelope of the incident laser pulse. We demonstrate that by introducing a frequency chirp in the incident pulse we are able to eliminate these Doppler shifts almost completely

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

    Bally J.

    2011-07-01

    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.

  18. Modelling of the Coriolis mass flowmeter

    Sultan, G.; Hemp, J.

    1989-08-01

    The Coriolis mass flowmeter is modelled by using the theory of vibrating beams. Tube deformations for the fundamental mode and for the next two modes of natural (out-of-plane) vibration are worked out for a U-tube configuration. Predictions of the relative phase of the vibration at two points are compared with measurements carried out on the "Micro Motion" industrial meter in water and kerosene flow rigs.

  19. Velocity gradients in spatially resolved laser Doppler flowmetry and dynamic light scattering with confocal and coherence gating

    Uribe-Patarroyo, Néstor; Bouma, Brett E.

    2016-08-01

    Dynamic light scattering (DLS) is widely used to characterize diffusive motion to obtain precise information on colloidal suspensions by calculating the autocorrelation function of the signal from a heterodyne optical system. DLS can also be used to determine the flow velocity field in systems that exhibit mass transport by incorporating the effects of the deterministic motion of scatterers on the autocorrelation function, a technique commonly known as laser Doppler flowmetry. DLS measurements can be localized with confocal and coherence gating techniques such as confocal microscopy and optical coherence tomography, thereby enabling the determination of the spatially resolved velocity field in three dimensions. It has been thought that spatially resolved DLS can determine the axial velocity as well as the lateral speed in a single measurement. We demonstrate, however, that gradients in the axial velocity of scatterers exert a fundamental influence on the autocorrelation function even in well-behaved, nonturbulent flow. By obtaining the explicit functional relation between axial-velocity gradients and the autocorrelation function, we show that the velocity field and its derivatives are intimately related and their contributions cannot be separated. Therefore, a single DLS measurement cannot univocally determine the velocity field. Our extended theoretical model was found to be in good agreement with experimental measurements.

  20. What's behind the mask? A look at blood flow changes with prolonged facial pressure and expression using laser Doppler imaging.

    Van-Buendia, Lan B; Allely, Rebekah R; Lassiter, Ronald; Weinand, Christian; Jordan, Marion H; Jeng, James C

    2010-01-01

    Clinically, the initial blanching in burn scar seen on transparent plastic face mask application seems to diminish with time and movement requiring mask alteration. To date, studies quantifying perfusion with prolonged mask use do not exist. This study used laser Doppler imaging (LDI) to assess perfusion through the transparent face mask and movement in subjects with and without burn over time. Five subjects fitted with transparent face masks were scanned with the LDI on four occasions. The four subjects without burn were scanned in the following manner: 1) no mask, 2) mask on while at rest, 3) mask on with alternating intervals of sustained facial expression and rest, and 4) after mask removal. Images were acquired every 3 minutes throughout the 85-minute study period. The subject with burn underwent a shortened scanning protocol to increase comfort. Each face was divided into five regions of interest for analysis. Compared with baseline, mask application decreased perfusion significantly in all subjects (P change during the rest period. There were no significant differences with changing facial expression in any of the regions of interest. On mask removal, all regions of the face demonstrated a hyperemic effect with the chin (P = .05) and each cheek (P constantly low while wearing the face mask, despite changing facial expressions. Changing facial expressions with the mask on did not alter perfusion. Hyperemic response occurs on removal of the mask. This study exposed methodology and statistical issues worth considering when conducting future research with the face, pressure therapy, and with LDI technology. PMID:20453735

  1. Laser-Doppler flowmetry at large interoptode spacing in human tibia diaphysis: Monte Carlo simulations and preliminary experimental results

    Laser-Doppler flowmetry (LDF) is an outstanding tool to monitor blood flow in a continuous and non-invasive way. In this work, we study LDF at large interoptode spacing applied to a human bone model (i.e. tibia diaphysis). To that aim, we first performed an extensive set of Monte Carlo (MC) simulations for 10 and 25 mm interoptode spacing. Second, we have assembled a dedicated LDF instrumentation based on an optimized industrial avalanche photo-detector. We performed LDF experimental measurements on human muscle using well-known physiological protocols, which confirmed the reliability of our instrumentation and the relevance of the LDF algorithms tested with the MC simulations. In a second set, we repeated the measurements on human tibia diaphysis. Again, the experiments corroborate the MC simulations and demonstrate the effectiveness of LDF to monitor blood perfusion in bone. The proposed technique has great potential for non-invasive neuro-vascular studies since it will certainly help to reveal the mechanisms underlying the interaction between bone/bone marrow, the circulatory system and the nervous system. (note)

  2. Multifractal analysis of central (electrocardiography) and peripheral (laser Doppler flowmetry) cardiovascular time series from healthy human subjects

    Analysis of the cardiovascular system (CVS) activity is important for several purposes, including better understanding of heart physiology, diagnosis and forecast of cardiac events. The central CVS, through the study of heart rate variability (HRV), has been shown to exhibit multifractal properties, possibly evolving with physiologic or pathologic states of the organism. An additional viewpoint on the CVS is provided at the peripheral level by laser Doppler flowmetry (LDF), which enables local blood perfusion monitoring. We report here for the first time a multifractal analysis of LDF signals through the computation of their multifractal spectra. The method for estimation of the multifractal spectra, based on the box method, is first described and tested on a priori known synthetic multifractal signals, before application to LDF data. Moreover, simultaneous recordings of both central HRV and peripheral LDF signals, and corresponding multifractal analyses, are performed to confront their properties. With the scales chosen on the partition functions to compute Renyi exponents, LDF signals appear to have broader multifractal spectra compared to HRV. Various conditions for LDF acquisitions are tested showing larger multifractal spectra for signals recorded on fingers than on forearms. The results uncover complex interactions at central and peripheral CVS levels

  3. Non-invasive laser Doppler perfusion measurements of large tissue volumes and human skeletal muscle blood RMS velocity

    This study proposes the implementation of an algorithm allowing one to derive absolute blood root-mean-square (RMS) velocity values from laser Doppler perfusion meter (LDP) data. The algorithm is based on the quasi-elastic light scattering theory and holds for multiple scattering. While standard LDP measurements are normally applicable to a small region of interest (∼1 mm2), the present method allows the analysis of both small and large tissue volumes with small and large interoptode spacings (e.g., 1.5 cm). The applicability and the limits of the method are demonstrated with measurements on human skeletal muscle using a custom-built near-infrared LDP meter. Human brachioradialis muscle RMS velocity values of 9.99 ± 0.01 and 5.58 ± 0.03 mm s-1 at 1.5 cm and of 5.18 ± 0.01 and 2.54 ± 0.09 mm s-1 at 2 cm were found when the arm was (a) at rest and (b) occluded, respectively. At very large optode spacings or very high moving particle densities, the theory developed here would need to be amended to take into account second-order effects

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

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

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

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

    2012-04-01

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

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

    Arturo Brunetti

    2012-12-01

    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.

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

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

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

    Vettorello, Gianfranco; Marini, Leonardo

    2009-06-01

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

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

    Michael Kragh

    2002-01-01

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

  10. Theoretical Investigation of Guide Wave Flowmeter

    Sato, Harumichi; Lebedev, Maxim; Akedo, Jun

    2007-07-01

    Cylindrical pipes are widely used in industries such as nuclear power plants and micro total analysis systems (μTAS). Measuring the flow rate of fluid in such pipes is critical. Ultrasonic flowmeters are noncontact, nondestructive, and easy-to-use devices, and are therefore widely used. However, typical bulk-wave-based ultrasonic flowmeters cannot be used for pipes narrower than the wavelength of bulk waves. For such pipes, we are currently developing a “guide wave flowmeter” that uses guide waves instead of bulk waves. Previously, we theoretically and experimentally investigated a pipe filled with quiescent fluid for all modes [Jpn. J. Appl. Phys. 45 (2006) 4573]. In this study, we expanded our theoretical investigation to a cylindrical pipe containing flowing fluid, and then compared the results with experimental results. Both the theoretical and experimental results revealed that the flow rate can be determined by measuring the sound velocity (propagation time) of guide waves. This is the operating principle of our guide wave flowmeter.

  11. Theory of transit time ultrasonic flowmeters

    Hemp, J.

    1982-09-01

    A theory of transit time ultrasonic flowmeters for clean fluids is developed from the equations of fluid mechanics applied simultaneously to the fluid and the sound vibrations. These equations are linearized (weak sound) and use is made of the electroacoustic reciprocity theorem to give a relation between the voltages and currents at the transducer terminals and the fluid velocity. The technique of "reciprocal operation" of a transit time ultrasonic flowmeter is described and the way this technique eliminates zero drift is explained. The theory can be applied to meters with broad sound beams (which provide a better average over velocity profiles) or meters in which the wavelength of sound is not necessarily small compared with the duct diameter. Small modificaition of the sound field (due to flow) is assumed and the resulting phase (or amplitude) shift of the received signal is expressed as an integral throughout the fluid of the dot product of the fluid velocity and a weight vector defined in terms of the sound fields in the stationary fluid. Simple flowmeter designs which approach the ideal of complete immunity to velocity distribution are described.

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

    W. A. Cooper

    2014-09-01

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

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

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

    1991-01-01

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

  14. Comparison Test and its Evaluation of Flowmeters for Heat Meter

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

    2010-06-01

    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.

  15. 激光多普勒效应实验仪的设计%The Design of Experiment Instrument of Laser Doppler Effect

    郝建华; 孙华燕

    2001-01-01

    为了解决激光多普勒效应在实验室演示比较困难问题,介绍了一种采用双光栅法实现激光多普勒效应的实验仪器,分析了双光栅法多普勒效应原理,给出了该仪器的组成结构,并分析了该仪器的特点。实验表明:采用双光栅法实现激光多普勒效应操作简单、效果明显。%In order to solve the problem that laser Doppler effect is difficult to demonstrate in laboratory. The paper introduces a kind of experiment instrument of laser Doppler effect based on double grating .The double grating principle of Doppler effect and constitute frame of experiment instrument are analyzed . The characteristics of the experiment instrument are also present . Experiments show it is easy to manipulate and the effectiveness is obvious in this way.

  16. Extrinsic factors affecting accuracy of ultrasonic flowmeters for LMFBRs

    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

  17. Doppler limited laser spectroscopy on hafnium lines. Pt. II. Hyperfine structure of odd-parity levels

    For pt.I see ibid., vol.6, p.303-10, 1999. The hyperfine structure of selected odd-parity levels of the configurations 5d6s 26p and 5d 26s6p of 177Hf I was studied in 10 lines lying in the red spectral region. Hyperfine spectra were obtained by the method of laser induced fluorescence in the plasma of a liquid nitrogen cooled hollow cathode discharge. The observed hyperfine structure constants A and B, together with results from earlier studies were analyzed by means of a parametric method. The interpretation has been carried out based on a refined multiconfigurational fine structure calculation including the main Rydberg series configurations mutually interacting. The set of fine structure parameters as well as the leading eigenvector percentages of levels relevant for this paper are given. The following single electron HFS parameters were deduced for 177Hf: a015d = 98.8(0.8)MHz, a016p=204.6 (6.4)MHz,b025d=4129 (133)MHz, b026p=7847(266)MHz for the lowest configuration. (orig.)

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

    Bakule, P

    1998-01-01

    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...

  19. Acoustic velocity measurement by means of Laser Doppler Velocimetry: Development of an Extended Kalman Filter and validation in free-field measurement

    Le Duff, Alain; Plantier, Guy; Valière, Jean C.; Gazengel, Bruno

    2016-03-01

    A signal processing technique, based on the use of an Extended Kalman Filter, has been developed to measure sound fields by means of Laser Doppler Velocimetry in weak flow. This method allows for the parametric estimation of both the acoustic particle and flow velocity for a forced sine-wave excitation where the acoustic frequency is known. The measurements are performed from the in-phase and the quadrature components of the Doppler downshifted signal thanks to an analog quadrature demodulation technique. Then, the estimated performance is illustrated by means of Monte-Carlo simulations obtained from synthesized signals and compared with asymptotic and analytical forms for the Cramer-Rao Bounds. Results allow the validity domain of the method to be defined and show the availability for free-field measurements in a large range. Finally, an application based on real data obtained in free field is presented.

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

    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

  1. Pulsatile blood flow in human bone assessed by laser-Doppler flowmetry and the interpretation of photoplethysmographic signals

    Human bone blood flow, mean blood speed and the number of moving red blood cells were assessed (in arbitrary units), as a function of time, during one cardiac cycle. The measurements were obtained non-invasively on five volunteers by laser-Doppler flowmetry at large interoptode spacing. The investigated bones included: patella, clavicle, tibial diaphysis and tibial malleolus. As hypothesized, we found that in all bones the number of moving cells remains constant during cardiac cycles. Therefore, we concluded that the pulsatile nature of blood flow must be completely determined by the mean blood speed and not by changes in blood volume (vessels dilation). Based on these results, it is finally demonstrated using a mathematical model (derived from the radiative transport theory) that photoplethysmographic (PPG) pulsations observed by others in the literature, cannot be generated by oscillations in blood oxygen saturation, which is physiologically linked to blood speed. In fact, possible oxygen saturation changes during pulsations decrease the amplitude of PPG pulsations due to specific features of the PPG light source. It is shown that a variation in blood oxygen saturation of 3% may induce a negative change of ∼1% in the PPG signal. It is concluded that PPG pulsations are determined by periodic ‘positive’ changes of the reduced scattering coefficient of the tissue and/or the absorption coefficient at constant blood volume. No explicit experimental PPG measurements have been performed. As a by-product of this study, an estimation of the arterial pulse wave velocity obtained from the analysis of the blood flow pulsations give a value of 7.8 m s−1 (95% confidence interval of the sample mean distribution: [6.7, 9.5] m s−1), which is perfectly compatible with data in the literature. We hope that this note will contribute to a better understanding of PPG signals and to further develop the domain of the vascular physiology of human bone. (note)

  2. Laser Doppler Vibrometer Based Examination of the Efficiency of Introducing Artificial Delaminations into Composite Shells

    Kustroń Kamila

    2015-09-01

    Full Text Available During its operation, the laminate shell of the watercraft hull can be exposed to local stability losses caused by the appearance and development of delaminations. The sources of these delaminations are discontinuities, created both in the production process and as a result of bumps of foreign bodies into the hull in operation. In the environment of fatigue loads acting on the hull, the delaminations propagate and lead to the loss of load capacity of the hull structure. There is a need to improve diagnostic systems used in Structural Health Monitoring (SHM of laminate hull elements to detect and monitor the development of the delaminations. Effective diagnostic systems used for delamination assessment base on expert systems. Along with other tools, the expert diagnostic advisory systems make use of the non-destructive examination method which consists in generating elastic waves in the hull shell structure and observing their changes by comparing the recorded signal with damage patterns collected in the expert system database. This system requires introducing certain patterns to its knowledge base, based on the results of experimental examinations performed on specimens with implemented artificial delaminations. The article presents the results of the examination oriented on assessing the delaminations artificially generated in the structure of glass- and carbon-epoxy laminates by introducing local non-adhesive layers with the aid of thin polyethylene film, teflon insert, or thin layer of polyvinyl alcohol. The efficiency of each method was assessed using laser vibrometry. The effect of the depth of delamination position in the laminate on the efficiency of the applied method is documented as well.

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

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

    2008-01-01

    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...

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

    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.)

  5. Development of small size Coriolis Mass Flowmeter

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

  6. Ultrasonic flowmeters: temperature gradients and transducer geometry effects.

    Willatzen, M

    2003-03-01

    Ultrasonic flowmeter performance is addressed for the case of cylindrically shaped flowmeters employing two reciprocal ultrasonic transducers A and B so as to measure time-of-flight differences between signals transmitted from transducer A towards B followed by an equivalent signal transmitted from transducer B towards A. In the case where a liquid flows through the flowmeter's measuring section ("spoolpiece"), the arrival times of the two signals differ by an amount related to the flow passing between the two transducers. Firstly, a detailed study of flow measurement errors with mean flow in the laminar flow regime is carried out as a function of the mode index and the transducer diameter/cylinder diameter ratio in the case where no temperature gradients are present in the flowmeter sensor. It is shown that all modes except the fundamental mode overestimate the mean flow by a factor of 33.33% while excitation of the fundamental mode solely give error-free measurements. The immediate consequences are that the flowmeter error decreases as the transducer diameter/cylinder diameter ratio approaches 1 from 0 reflecting the fact that the excitation level of the fundamental mode increases from almost 0 to 1 as this ratio approaches 1 from 0. Secondly, the effect on flowmeter performance due to flow-induced temperature gradients is examined. It is shown that the presence of temperature gradients leads to flowmeter errors at the higher-flow values even in the case where the fundamental mode is the only mode excited. It is also deduced that flowmeter errors in general depend on the distance between transducers A and B whether temperature gradients exist or not. This conclusion is not reflected in the usual definition of flowmeter errors given by the so-called mode-dependent deviation of measurement introduced in earlier works. PMID:12565074

  7. Documentation and Instructions for Running Two Python Scripts that Aid in Setting up 3D Measurements using the Polytec 3D Scanning Laser Doppler Vibrometer.

    Rohe, Daniel Peter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-08-24

    Sandia National Laboratories has recently purchased a Polytec 3D Scanning Laser Doppler Vibrometer for vibration measurement. This device has proven to be a very nice tool for making vibration measurements, and has a number of advantages over traditional sensors such as accelerometers. The non-contact nature of the laser vibrometer means there is no mass loading due to measuring the response. Additionally, the laser scanning heads can position the laser spot much more quickly and accurately than placing an accelerometer or performing a roving hammer impact. The disadvantage of the system is that a significant amount of time must be invested to align the lasers with each other and the part so that the laser spots can be accurately positioned. The Polytec software includes a number of nice tools to aid in this procedure; however, certain portions are still tedious. Luckily, the Polytec software is readily extensible by programming macros for the system, so tedious portions of the procedure can be made easier by automating the process. The Polytec Software includes a WinWrap (similar to Visual Basic) editor and interface to run macros written in that programming language. The author, however, is much more proficient in Python, and the latter also has a much larger set of libraries that can be used to create very complex macros, while taking advantage of Python’s inherent readability and maintainability.

  8. A Mathematical Model of the Thermo-Anemometric Flowmeter

    Igor Korobiichuk

    2015-09-01

    Full Text Available A thermo-anemometric flowmeter design and the principles of its work are presented in the article. A mathematical model of the temperature field in a stream of biofuel is proposed. This model allows one to determine the fuel consumption with high accuracy. Numerical modeling of the heater heat balance in the fuel flow of a thermo-anemometric flowmeter is conducted and the results are analyzed. Methods for increasing the measurement speed and accuracy of a thermo-anemometric flowmeter are proposed.

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

    Meyer, Richard Scott

    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

  10. Ultrasonic Doppler blood flow meter for extracorporeal circulation

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

    2000-04-01

    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.

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

    Biedermann, Laura Butler

    2009-09-01

    A few of the many applications for nanowires are high-aspect ratio conductive atomic force microscope (AFM) cantilever tips, force and mass sensors, and high-frequency resonators. Reliable estimates for the elastic modulus of nanowires and the quality factor of their oscillations are of interest to help enable these applications. Furthermore, a real-time, non-destructive technique to measure the vibrational spectra of nanowires will help enable sensor applications based on nanowires and the use of nanowires as AFM cantilevers (rather than as tips for AFM cantilevers). Laser Doppler vibrometry is used to measure the vibration spectra of individual cantilevered nanowires, specifically multiwalled carbon nanotubes (MWNTs) and silver gallium nanoneedles. Since the entire vibration spectrum is measured with high frequency resolution (100 Hz for a 10 MHz frequency scan), the resonant frequencies and quality factors of the nanowires are accurately determined. Using Euler-Bernoulli beam theory, the elastic modulus and spring constant can be calculated from the resonance frequencies of the oscillation spectrum and the dimensions of the nanowires, which are obtained from parallel SEM studies. Because the diameters of the nanowires studied are smaller than the wavelength of the vibrometer's laser, Mie scattering is used to estimate the lower diameter limit for nanowires whose vibration can be measured in this way. The techniques developed in this thesis can be used to measure the vibrational spectra of any suspended nanowire with high frequency resolution Two different nanowires were measured - MWNTs and Ag{sub 2}Ga nanoneedles. Measurements of the thermal vibration spectra of MWNTs under ambient conditions showed that the elastic modulus, E, of plasma-enhanced chemical vapor deposition (PECVD) MWNTs is 37 {+-} 26 GPa, well within the range of E previously reported for CVD-grown MWNTs. Since the Ag{sub 2}Ga nanoneedles have a greater optical scattering efficiency than

  12. Improving the correlation of structural FEA models by the application of automated high density robotized laser Doppler vibrometry

    Chowanietz, Maximilian; Bhangaonkar, Avinash; Semken, Michael; Cockrill, Martin

    2016-06-01

    Sound has had an intricate relation with the wellbeing of humans since time immemorial. It has the ability to enhance the quality of life immensely when present as music; at the same time, it can degrade its quality when manifested as noise. Hence, understanding its sources and the processes by which it is produced gains acute significance. Although various theories exist with respect to evolution of bells, it is indisputable that they carry millennia of cultural significance, and at least a few centuries of perfection with respect to design, casting and tuning. Despite the science behind its design, the nuances pertaining to founding and tuning have largely been empirical, and conveyed from one generation to the next. Post-production assessment for bells remains largely person-centric and traditional. However, progressive bell manufacturers have started adopting methods such as finite element analysis (FEA) for informing and optimising their future model designs. To establish confidence in the FEA process it is necessary to correlate the virtual model against a physical example. This is achieved by performing an experimental modal analysis (EMA) and comparing the results with those from FEA. Typically to collect the data for an EMA, the vibratory response of the structure is measured with the application of accelerometers. This technique has limitations; principally these are the observer effect and limited geometric resolution. In this paper, 3-dimensional laser Doppler vibrometry (LDV) has been used to measure the vibratory response with no observer effect due to the non-contact nature of the technique; resulting in higher accuracy measurements as the input to the correlation process. The laser heads were mounted on an industrial robot that enables large objects to be measured and extensive data sets to be captured quickly through an automated process. This approach gives previously unobtainable geometric resolution resulting in a higher confidence EMA. This is

  13. Development of the Vortex Mass Flowmeter with Wall Pressure Measurement

    Li, Zhiyong; Sun, Zhiqiang

    2013-01-01

    Mass flow measurement is essential to the understanding and control of processes concerning fluid flow. The availability of reliable mass flowmeters, however, is far inadequate to meet the demand. In this paper we developed a practical vortex mass flowmeter with wall pressure measurement. The meter coefficient of mass flow rate was acquired through experiments with air at Reynolds numbers from 1.3×103 to 9.8×103. Here we show that the meter coefficient of mass flow rate is nearly constant at Reynolds numbers greater than 5.5×103. To further extend the lower limit, a correction factor related to the Reynolds number was introduced into the vortex mass flowmeter. The results show that the relative errors of the vortex mass flowmeter developed are basically within ±5%. This device can satisfy a diversity of requirements of mass flow measurement in engineering fields.

  14. Effects of alpha-trinositol on peripheral circulation in diabetic patients with critical limb ischaemia. A pilot study using laser Doppler fluxmetry, transcutaneous oxygen tension measurements and dynamic capillaroscopy

    Nilsson, L; Apelqvist, J; Edvinsson, L

    1998-01-01

    h infusion, resulting in a total dose of 2400 mg. Microcirculation was evaluated by means of laser doppler fluxmetry (LDF), transcutaneous oxygen tension (tcPO2) and dynamic capillaroscopy (CBV). RESULTS: Plasma concentration of alpha-trinositol reached a steady state level after 1 h following the...... start of the administration. There were no detectable changes in blood pressure or heart rate. Laser Doppler flux increased from 41% to 57.5% and tcPO2 changed from 116 to 91 s in "half time recovery" after occlusion. Capillary blood flow showed an increase in resting velocity from 0.1 to 0.5 mm/s at 24...

  15. A Cryogenic Helium Mass Flowmeter for the Large Haldron Collider

    Serio, Luigi

    2007-01-01

    This thesis is concerned with the design, development and testing of helium mass flowmeters based on different technologies to be used as diagnostic tools for the cryogenic system of the Large Hadron Collider at CERN, the European laboratory for particle physics. The flowmeters were designed and the performance assessed for liquid, supercritical and superfluid helium down to 1.8 K and with pressures up to 0.3 MPa. A testing regime and equipment to enable the performance of a...

  16. Status of the Recent Magnetic Flowmeters

    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

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

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

    1989-01-01

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

  18. Shigeo Satomura: 60 years of Doppler ultrasound in medicine.

    Coman, Ioan M; Popescu, Bogdan A

    2015-01-01

    This year we celebrate 60 years since Shigeo Satomura published the first measurements of the Doppler shift of ultrasonic signals from a beating heart. He demonstrated that Doppler signals can be retrieved from heart movements when insonated with 3 MHz ultrasonic waves. Later, togheter with Ziro Kaneko, he constructed the first Doppler flowmeter to measure the blood flow velocities in peripheral and extracranial brain-supplying vessels using ultrasounds. They proved that ultrasonic Doppler signals from arteries and veins can be recorded from the surface of the skin and pioneered transcutaneous flow analysis in systole and diastole in both normal and diseased blood vessels. These were the first medical applications of Doppler sonography and impressive technologic innovations have been continuing ever since. Over time, Doppler techniques became a key player in diagnostic ultrasound for hemodynamic assessment, replacing cardiac catheterization in many clinical settings. PMID:26699126

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

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

    2012-12-01

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

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

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

    2012-01-01

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

  1. Izmerenie vektora skorosti lazernym dopplerovskim anemometrom (LDA s volokonno-opticheskimi traktami[Measurement of the velocity vector of the laser Doppler anemometer (LDA with fiber-optic tracts

    S. N. Khotyaintsev

    1982-12-01

    Full Text Available The problems encountered in the development of laser Doppler velocity vector meter optical fiber paths. The scheme of the meter, including three-dimensional velocity meter made by differential circuit. Describes the experimental setup and the results of the experiment by measuring the two projections of the velocity vector.

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

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

    2014-01-01

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

  3. Highly spatially resolved velocity measurements of a turbulent channel flow by a fiber-optic heterodyne laser-Doppler velocity-profile sensor

    Shirai, K.; Pfister, T.; Buettner, L.; Czarske, J. [Dresden University of Technology (TU Dresden), Department of Electrical Engineering and Information Technology, Chair for Measurement and Testing Techniques, Dresden (Germany); Mueller, H. [Physikalisch-Technische Bundesanstalt Braunschweig (PTB), Department 1.4 Gas Flow, Braunschweig (Germany); Becker, S.; Lienhart, H.; Durst, F. [Institute of Fluid Mechanics (LSTM), Friedrich-Alexander-University Erlangen-Nuernberg, Erlangen (Germany)

    2006-03-15

    Velocity measurements with a high spatial resolution are important in turbulent flow research. In this paper, we report on the development of a new fiber-optic laser-Doppler velocity-profile sensor exhibiting a spatial resolution of up to 5 {mu}m and its application to turbulent boundary layers. The sensor developed in the present work employs a frequency-division-multiplexing technique in order to separate two measurement signals from the two fringe systems. Velocity measurements close to zero at the solid wall were realized using heterodyne technique. The use of fiber optics improved a robustness of the sensor. The measurement accuracy of the sensor was experimentally investigated with respect to the spatial resolution and velocity. Universal velocity profile of a turbulent flow was obtained in a fully developed channel flow. Mean and fluctuating velocity are presented with a high spatial resolution. (orig.)

  4. Pitot-tube flowmeter for quantification of airflow during sleep

    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 H2O 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 pneumtachograph signal a (β1 = 1.08 V L−1 s−1; β0 = 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

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

    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 β-irradiation. Methods.-Ten pigs were given β-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 β-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 < 0.001), compared to the adjacent control area. On the other hand, as from day 7, the resting and the stimulated microcirculation varied little, except for a reduction of the slope p by a factor of 2 (p < 0.05) after the strongest radiation dose. Conclusion. -After acute irradiation, the increase in the resting cutaneous microcirculation may correspond to immediate but transitory capillary vasodilatation that accompanies the initial erythema in accidental irradiation. The absence of vascular response to thermal stimulation seems to be a good means of reaching an early diagnosis of delayed cutaneous radiation necrosis. (authors)

  6. Azimuthal Doppler Effect in Optical Vortex Spectroscopy

    Aramaki, Mitsutoshi; Yoshimura, Shinji; Toda, Yasunori; Morisaki, Tomohiro; Terasaka, Kenichiro; Tanaka, Masayoshi

    2015-11-01

    Optical vortices (OV) are a set of solutions of the paraxial Helmholtz equation in the cylindrical coordinates, and its wave front has a spiral shape. Since the Doppler shift is caused by the phase change by the movement in a wave field, the observer in the OV, which has the three-dimensional structured wave front, feels a three-dimensional Doppler effect. Since the multi-dimensional Doppler components are mixed into a single Doppler spectrum, development of a decomposition method is required. We performed a modified saturated absorption spectroscopy to separate the components. The OV and plane wave are used as a probe beam and pump beam, respectively. Although the plane-wave pump laser cancels the z-direction Doppler shift, the azimuthal Doppler shift remains in the saturated dip. The spatial variation of the dip width gives the information of the azimuthal Doppler shift. The some results of optical vortex spectroscopy will be presented.

  7. Laser-induced line-narrowing effects in coupled Doppler-broadened transitions. II - Standing-wave features.

    Feldman, B. J.; Feld, M. S.

    1972-01-01

    Previous theoretical results on the influence of a laser on the line shape of a coupled transition (laser-induced line narrowing) have been restricted to the case where the laser is detuned from the center of its atomic gain profile or is in the form of a traveling wave. The present paper extends these results to the case where the laser is an intense standing-wave field tunable to the center of its atomic gain profile (conditions for Lamb dip). A theoretical solution of the problem is developed, and a detailed discussion of line shapes and physical processes involved is included.

  8. Numerical calibration of a Lorentz force flowmeter

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

  9. Calibration and testing of selected portable flowmeters for use on large irrigation systems

    Luckey, Richard R.; Heimes, Frederick J.; Gaggiani, Neville G.

    1980-01-01

    Existing methods for measuring discharge of irrigation systems in the High Plains region are not suitable to provide the pumpage data required by the High Plains Regional Aquifer System Analysis. Three portable flowmeters which might be suitable for obtaining fast and accurate discharge measurements on large irrigation systems were tested. A propeller type gaged-pipe meter, a Doppler meter, and a transient-time meter were tested under both laboratory and field conditions during 1979. The gated-pipe meter was found to be difficult to use and sensitive to particulate matter in the fluid. The Doppler meter, while easy to use, would not function on steel pipe 6 inches or larger in diameter, or on aluminum pipe larger than 8 inches in diameter. The transient-time meter was more difficult to use than the other two meters; however, this instrument provided a high degree of accuracy and reliability under a variety of conditions. Of the three meters tested, only the transient-time meter was found to be suitable for providing reliable discharge measurements on the variety of irrigation system used in the High Plains region. (USGS)

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

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

    2015-01-01

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

  11. Measurement of transitional flow in pipes using ultrasonic flowmeters

    The accuracy of an ultrasonic flowmeter depends on the ratio k of average profile velocity of pipe and average velocity of an ultrasonic propagation path. But there is no appropriate method of calculating k for transition flow. In this paper, the velocity field of the transition flow in a pipe is measured by particle image velocimetry. On this basis, the k of U-shaped and V-shaped ultrasonic flowmeter is obtained when Reynolds number is between 2000 and 20 000. It is shown that the k is constant when the Reynolds number is in the range of 2000–2400 and 5400–20 000, and the k decreases with the increasing of Re when the Reynolds number is 2400–5400. The results of study can be used to improve the measurement accuracy of ultrasonic flowmeters when flow is transition flow and can provide help for the study of pipe flow. (paper)

  12. Measurement of transitional flow in pipes using ultrasonic flowmeters

    Zheng-Gang, Liu; Guang-Sheng, Du; Zhu-Feng, Shao; Qian-Ran, He; Chun-Li, Zhou

    2014-10-01

    The accuracy of an ultrasonic flowmeter depends on the ratio k of average profile velocity of pipe and average velocity of an ultrasonic propagation path. But there is no appropriate method of calculating k for transition flow. In this paper, the velocity field of the transition flow in a pipe is measured by particle image velocimetry. On this basis, the k of U-shaped and V-shaped ultrasonic flowmeter is obtained when Reynolds number is between 2000 and 20 000. It is shown that the k is constant when the Reynolds number is in the range of 2000-2400 and 5400-20 000, and the k decreases with the increasing of Re when the Reynolds number is 2400-5400. The results of study can be used to improve the measurement accuracy of ultrasonic flowmeters when flow is transition flow and can provide help for the study of pipe flow.

  13. Measurement of transitional flow in pipes using ultrasonic flowmeters

    Zheng-Gang, Liu; Guang-Sheng, Du; Zhu-Feng, Shao; Qian-Ran, He; Chun-Li, Zhou, E-mail: lzhenggang@sdu.edu.cn [School of Energy and Power Engineering, Qian-Fo-shan campus, Shandong University, Jinan City 250061, Shandong Province (China)

    2014-10-01

    The accuracy of an ultrasonic flowmeter depends on the ratio k of average profile velocity of pipe and average velocity of an ultrasonic propagation path. But there is no appropriate method of calculating k for transition flow. In this paper, the velocity field of the transition flow in a pipe is measured by particle image velocimetry. On this basis, the k of U-shaped and V-shaped ultrasonic flowmeter is obtained when Reynolds number is between 2000 and 20 000. It is shown that the k is constant when the Reynolds number is in the range of 2000–2400 and 5400–20 000, and the k decreases with the increasing of Re when the Reynolds number is 2400–5400. The results of study can be used to improve the measurement accuracy of ultrasonic flowmeters when flow is transition flow and can provide help for the study of pipe flow. (paper)

  14. Research of the high performance low temperature vortex street flowmeter

    Gao, Feng; Chen, Yang; Zhang, Zhen-peng; Geng, Wei-guo

    2007-07-01

    Flow measurement is the key method for R&D and operation monitoring of liquid rocket engine. Therefore, it is important to measure flux of low temperature liquid propellants for the liquid hydrogen/liquid oxygen or the liquid oxygen/kerosene rocket engine. Presently in China, the level meter and the turbine flowmeter are usually used in the experimentation of the liquid hydrogen/liquid oxygen rocket engine. The level meter can only scale average flux and the precision of the turbine flowmeter (the measuring wild point is 1.5%) can not be ensured due to the reason which there is not devices of low temperature real-time demarcation in China. Therefore, it is required to research the high performance low temperature flow measurement equipment and the vortex street flowmeter is selected because of its advantages. In the paper, some key techniques of low temperature vortex street flowmeter are researched from the design aspect. Firstly, the basic theoretical research of vortex street flowmeter includes signal detection method, shape of vortex producer and effects of dimension of vertex producer to vortex quality. Secondly, low temperature vortex street flowmeter adopts the method of piezoelectric components stress mode. As for the weakness of phase-change, lattice change and fragility for many piezoelectric materials in low temperature, it can not be fulfilled piezoelectric signal and mechanism performance under this condition. Some piezoelectric materials which can be used in low temperature are illustrated in the paper by lots of research in order for the farther research. The article places emphasis upon low temperature trait of piezoelectric materials, and the structure designs of signal detector and calculation of stress, electric charge quantity and heat transfer.

  15. Modelling of flow in pipes and ultrasonic flowmeter bodies

    Matas, Richard; Cibera, Vaclav; Syka, Tomas

    2014-03-01

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

  16. Modelling of flow in pipes and ultrasonic flowmeter bodies

    Matas Richard

    2014-03-01

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

  17. Integration of a laser doppler vibrometer and adaptive optics system for acoustic-optical detection in the presence of random water wave distortions

    Land, Phillip; Robinson, Dennis; Roeder, James; Cook, Dean; Majumdar, Arun K.

    2016-05-01

    A new technique has been developed for improving the Signal-to-Noise Ratio (SNR) of underwater acoustic signals measured above the water's surface. This technique uses a Laser Doppler Vibrometer (LDV) and an Adaptive Optics (AO) system (consisting of a fast steering mirror, deformable mirror, and Shack-Hartmann Wavefront Sensor) for mitigating the effect of surface water distortions encountered while remotely recording underwater acoustic signals. The LDV is used to perform non-contact vibration measurements of a surface via a two beam laser interferometer. We have demonstrated the feasibility of this technique to overcome water distortions artificially generated on the surface of the water in a laboratory tank. In this setup, the LDV beam penetrates the surface of the water and travels down to be reflected off a submerged acoustic transducer. The reflected or returned beam is then recorded by the LDV as a vibration wave measurement. The LDV extracts the acoustic wave information while the AO mitigates the water surface distortions, increasing the overall SNR. The AO system records the Strehl ratio, which is a measure of the quality of optical image formation. In a perfect optical system the Strehl ratio is unity, however realistic systems with imperfections have Strehl ratios below one. The operation of the AO control system in open-loop and closed-loop configurations demonstrates the utility of the AO-based LDV for many applications.

  18. FLOWCER - a flowmeter based on radiotracer techniques

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

  19. 基于DSP的超声波流量计的研究%Study of ultrasonic flowmeter based on DSP

    杜文广; 翟金龙

    2011-01-01

    Ultrasonic flowmeter has the advantage of no contact with measured medium, so it has been continuously studied and applied in many fields, and it played a huge role. This paper designs the flowmeter that is based on DSP and it's principle is Doppler effect, and completes the hardware and software design. Finally, this paper simulates FIR digital filter and FFT algorithm, and it is proved the feasibility of the program.%超声波流量计因为具有不接触被测介质等优点,已经被不断研究并应用在许多领域,发挥了巨大的作用.设计了基于DSP,以多普勒效应为原理的超声波流量计,完成了硬件设计和软件设计.最后对FIR数字滤波器和FFT算法进行了仿真,证明了方案的可行性.

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

    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)

  1. A thermal peripheral blood flowmeter with contact force compensation

    Sim, Jai Kyoung; Youn, Sechan; Cho, Young-Ho

    2012-12-01

    This paper presents a thermal peripheral blood flowmeter where a force sensor is integrated to compensate the blood flow measurement. Since blood flow is highly sensitive to the contact force between the sensor and skin, previous blood flowmeters needed to be fixed on the skin with a constant contact force. We integrate a force sensor with a thermal blood flowmeter to measure both blood flow and contact force simultaneously for force-compensated blood flow measurement. The blood flowmeter presented here is composed of a resistance temperature detector and a piezoresistive force sensor and was fabricated by surface and bulk micromachining techniques. In the experimental measurement, the blood flow linearly decreased with the contact force at the rate of 31.7% N-1. By using the measured compensation coefficient, the device showed a constant blood flow with the maximum difference of 6.4% over the contact force variation of 1-3 N, and otherwise showed the maximum difference of 75.0%. The present device is suitable for applications with portable biomedical instrumentation or air-conditioning systems for the estimation of human thermoregulation status.

  2. Self monitoring flowmeter with diversity; Selbstueberwachender Durchflusssensor mit diversitaerer Redundanz

    Mueller, R.; Nuber, M.; Werthschuetzky, R. [Technische Univ. Darmstadt (Germany). Inst. fuer EMK

    2005-04-01

    A self monitoring fluid flowmeter with diversity is presented. The sensor uses the differential pressure and the vortex flow measuring method. Both measurands are taken by only one pressure sensor in order to reduce the number of additional components. The self monitoring algorithm is based on the different characteristics of the two measuring methods. (orig.)

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

    Kolodny, Edwin H.; Patricia A. Broderick

    2010-01-01

    Neuromolecular Imaging (NMI) based on adsorptive electrochemistry, combined with Dual Laser Doppler Flowmetry (LDF) is presented herein to investigate the brain neurochemistry affected by enoxaparin (Lovenox®), an antiplatelet/antithrombotic medication for stroke victims. NMI with miniature biosensors enables neurotransmitter and neuropeptide (NT) imaging; each NT is imaged with a response time in milliseconds. A semiderivative electronic reduction circuit images several NT’s selectively and ...

  4. Field test of an all-semiconductor laser-based coherent continuous-wave Doppler lidar for wind energy applications

    Sjöholm, Mikael; Dellwik, Ebba; Hu, Qi;

    -produced all-semiconductor laser. The instrument is a coherent continuous-wave lidar with two fixed-focus telescopes for launching laser beams in two different directions. The alternation between the telescopes is achieved by a novel switching technique without any moving parts. Here, we report results from......The wind energy industry is gaining interest in prevision of the rotor inflow for turbine control. The potential benefits are increased power production due to better alignment of the rotor to the mean wind direction as well as prolonged lifetime of the turbine due to load reductions. Several lidar......-based instruments for wind turbine mounting are now commercially available. However, they suffer from high price and bulkiness. Therefore, the Technical University of Denmark has, in collaboration with the Danish company Windar Photonics A/S, developed a compact and low-cost lidar called WindEye based on a mass...

  5. Local measurements in two-phase flow using a double-sensor conductivity probes and laser doppler anemometry in a vertical pipe

    An upward isothermal co-current air-water flow in a vertical pipe (50.2 mm inner diameter) has been experimental investigated. Local measurements of void fraction, interfacial area concentration (IAC), and interfacial velocity and Sauter mean diameter were measured using a double sensor conductivity probe. Liquid velocity and turbulence intensity were measured using laser Doppler anemometry. Different air-water flow configurations was investigated for a liquid flow rate ranged from 0.29 m/s to 2 m/s and a void fraction up to 15%. For each two-phase flow configuration 15 radial position and three axial positions was measured by the conductivity probe methodology, and several radial profiles was measured with LDA at different axial positions. Two theoretical calibration factors have been defined to relate the mean measurable parameter to the interfacial area concentrations obtained and the measured bubbles, including the missed bubbles. Those factors include the effects of bubble motions, and probe spacing. These calibration factors were obtained through new analytical and numerical method, using a Monte Carlo approach. (author)

  6. 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

    Kulhalli Prabhakar

    2005-01-01

    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.

  7. Local cooling reduces skin ischemia under surface pressure in rats: an assessment by wavelet analysis of laser Doppler blood flow oscillations

    The objectives of this study were to investigate the effects of local cooling on skin blood flow response to prolonged surface pressure and to identify associated physiological controls mediating these responses using the wavelet analysis of blood flow oscillations in rats. Twelve Sprague–Dawley rats were randomly assigned to three protocols, including pressure with local cooling (Δt = −10 °C), pressure with local heating (Δt = 10 °C) and pressure without temperature changes. Pressure of 700 mmHg was applied to the right trochanter area of rats for 3 h. Skin blood flow was measured using laser Doppler flowmetry. The 3 h loading period was divided into non-overlapping 30 min epochs for the analysis of the changes of skin blood flow oscillations using wavelet spectral analysis. The wavelet amplitudes and powers of three frequencies (metabolic, neurogenic and myogenic) of skin blood flow oscillations were calculated. The results showed that after an initial loading period of 30 min, skin blood flow continually decreased under the conditions of pressure with heating and of pressure without temperature changes, but maintained stable under the condition of pressure with cooling. Wavelet analysis revealed that stable skin blood flow under pressure with cooling was attributed to changes in the metabolic and myogenic frequencies. This study demonstrates that local cooling may be useful for reducing ischemia of weight-bearing soft tissues that prevents pressure ulcers. (paper)

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

    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

    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.

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

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

    2012-06-01

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

  10. Monitoring hypoxia induced changes in cochlear blood flow and hemoglobin concentration using a combined dual-wavelength laser speckle contrast imaging and Doppler optical microangiography system.

    Roberto Reif

    Full Text Available A synchronized dual-wavelength laser speckle contrast imaging (DWLSCI system and a Doppler optical microangiography (DOMAG system was developed to determine several ischemic parameters in the cochlea due to a systemic hypoxic challenge. DWLSCI can obtain two-dimensional data, and was used to determine the relative changes in cochlear blood flow, and change in the concentrations of oxyhemoglobin (HbO, deoxyhemoglobin (Hb and total hemoglobin (HbT in mice. DOMAG can obtain three-dimensional data, and was used to determine the changes in cochlear blood flow with single vessel resolution. It was demonstrated that during a hypoxic challenge there was an increase in the concentrations of Hb, a decrease in the concentrations of HbO and cochlear blood flow, and a slight decrease in the concentration of HbT. Also, the rate of change in the concentrations of Hb and HbO was quantified during and after the hypoxic challenge. The ability to simultaneously measure these ischemic parameters with high spatio-temporal resolution will allow the detailed quantitative analysis of several hearing disorders, and will be useful for diagnosing and developing treatments.

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

    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

  12. Laser Doppler flowmetry: an early diagnosis instrument in detecting the soft tissue changes that occur during radiotherapy to the head and neck area, clinical case report

    Petre, L. C.; Miron, M. I.; Ianes, E.

    2016-03-01

    Aim of the study: Our goal was to monitor soft tissue changes occurring during radiotherapy - both through clinical examination and using LDF - in order to establish Laser Doppler as an early diagnosis instrument in this situation, and also to assess what kind of dental procedures could be provided during radiotherapy, in order to increase patients' quality of life. Material and Method: Our study included two male patients, who received head and neck radiotherapy. Patient A, 68 years old, underwent 31 radiotherapy exposures. Patient B, 52 years old, underwent 24 exposures. They received a thorough clinical examination, and a LDF evaluation of gingival blood flow in areas close to the irradiated site, after the first, the 18th, and the last radiotherapy exposure. Results: Patient A presented radiotherapy induced mucositis, after the 18th radiotherapy exposure. After the last exposure the mucositis worsened, additionally, radiodermitis appeared on the neck. LDF showed an increase in blood flow of the irradiated area, even after the first exposure, and it persisted throughout treatment. Patient B showed no clinical changes, besides a hyperkeratinisation of the gingiva in the irradiated area, after the last exposure. LDF showed an overall increase in vascularity of the area throughout treatment. Discussion: Even after the first radiotherapy exposure, and also when clinical changes were not apparent, LDF measurements revealed an increase in blood flow in the gingiva of irradiated patients. LDF might allow us to establish the most appropriate moment in time for each dental treatment, in order to increase the quality of life.

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

    Tobias Strenger

    2013-10-01

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

  14. Dynamic testing of MEMS based on laser doppler effect%基于激光多普勒效应的MEMS的运动检测

    侯世博; 李醒飞; 贺少辉

    2009-01-01

    A system for testing transient velocities and displacements of MEMS is proposed. The system is based on differential laser Doppler effect. Frequency shift technology and wave filtering technology are used to process the signal and software Lab VIEW & Matlab are used to measure its moveme t parameters with the mothed of digital filtering technology and time-frequency analysis. An accurate and reliable method can be provided for the research on dynamic characteristics of MEMS.%提出了一种可以测量微机电系统(MEMS)面内瞬时速度和位移的测量系统.该系统利用差动激光多普勒效应,采用了频移技术和接收端的滤波技术将带有MEMS运动信息的光信号接收并解调,然后,利用LabVIEW和Matlab软件对采集的信号进行数字滤波和时频分析,从而得到被测器件的运动参量,为研究MEMS的动态特性提供了准确可靠的方法.

  15. Estimation of flow in aortocoronary grafts with a pulsed ultrasound Doppler meter.

    Segadal, L; Matre, K; Engedal, H; Resch, F; Grip, A

    1982-10-01

    A newly developed pulsed ultrasound Doppler meter was used for measurement of blood flow in aortocoronary vein grafts during operation. The results were compared with measurements obtained with conventional electromagnetic flowmetry. In 27 grafts, excellent agreement was found between electromagnetic flow probes thoroughly calibrated for varying hematocrit on fresh veins in vitro, and a clip-on type of Doppler probe (r = 0.86). In vitro calibration showed a close correspondence (r = 0.98) with the Doppler technique with no dependency on hematocrit and no need for zero calibration. The use of a conventional electromagnetic flowmeter showed strong dependency on recent calibration, both for saline and for varying hematocrit. Zero-calibration was necessary for every single graft measurement. The application of ultrasound Doppler meters of high quality together with clip-on probes of proper design proved to be superior to electromagnetic flowmetry for intraoperative blood flow measurements. PMID:6183771

  16. Phase and Frequency Matching-based Signal Processing Method for Coriolis Mass Flowmeters

    Tu Yaqing; Shen Yanlin; Zhang Haitao; Li Ming

    2016-01-01

    Signal processing precision of Coriolis mass flowmeters affects the measurement accuracy directly. To improve the measurement accuracy of Coriolis mass flowmeters, a phase and frequency matching-based signal processing method for Coriolis mass flowmeters is proposed. Estimated phase difference is obtained by means of frequency estimation, 90° phase shift, generating reference signals and cross-correlation. Simulated results demonstrate that the proposed method has better phase difference esti...

  17. Development of a wide range vortex shedding flowmeter for high-temperature helium gas

    Baker, S. P.; Ennis, R. M., Jr.; Herndon, P. G.

    1981-07-01

    A single flowmeter capable of meeting all the core flow test loop (CFTL) requirements was developed in order to provide significant economic and performance advantages in the operation of the loop. The development, conceptual design, and final design of a modified vortex shedding flowmeter are described. The results of extensive flow calibration of the flowmeter at the Colorado Engineering Experiment Station are presented. The report closes with recommendations for application of the VSFM to the CFTL and for future development work.

  18. Doppler tracking

    Thomas, Christopher Jacob

    This study addresses the development of a methodology using the Doppler Effect for high-resolution, short-range tracking of small projectiles and vehicles. Minimal impact on the design of the moving object is achieved by incorporating only a transmitter in it and using ground stations for all other components. This is particularly useful for tracking objects such as sports balls that have configurations and materials that are not conducive to housing onboard instrumentation. The methodology developed here uses four or more receivers to monitor a constant frequency signal emitted by the object. Efficient and accurate schemes for filtering the raw signals, determining the instantaneous frequencies, time synching the frequencies from each receiver, smoothing the synced frequencies, determining the relative velocity and radius of the object and solving the nonlinear system of equations for object position in three dimensions as a function of time are developed and described here.

  19. Comparison of UNL laser imaging and sizing system and a phase Doppler system for analyzing sprays from a NASA nozzle

    Alexander, Dennis R.

    1990-01-01

    Research was conducted on characteristics of aerosol sprays using a P/DPA and a laser imaging/video processing system on a NASA MOD-1 air assist nozzle being evaluated for use in aircraft icing research. Benchmark tests were performed on monodispersed particles and on the NASA MOD-1 nozzle under identical lab operating conditions. The laser imaging/video processing system and the P/DPA showed agreement on a calibration tests in monodispersed aerosol sprays of + or - 2.6 micron with a standard deviation of + or - 2.6 micron. Benchmark tests were performed on the NASA MOD-1 nozzle on the centerline and radially at 0.5 inch increments to the outer edge of the spray plume at a distance 2 ft downstream from the exit nozzle. Comparative results at two operation conditions of the nozzle are presented for the two instruments. For the 1st case studied, the deviation in arithmetic mean diameters determined by the two instruments was in a range of 0.1 to 2.8 micron, and the deviation in Sauter mean diameters varied from 0 to 2.2 micron. Severe operating conditions in the 2nd case resulted in the arithmetic mean diameter deviating from 1.4 to 7.1 micron and the deviation in the Sauter mean diameters ranging from 0.4 to 6.7 micron.

  20. Concentration measurement systems with stable solutions for binary gas mixtures using two flowmeters

    Youn, Chongho; Kawashima, Kenji; Kagawa, Toshiharu

    2011-06-01

    The previously proposed gas concentration measurement system (Yamazaki et al 2007 Meas. Sci. Technol. 18 2762-8) shows a considerable error for some combinations of gases. The error increases when the system of equations determining mole fractions becomes a mathematically ill-conditioned system. Because the parameters of the equations reflect the material properties of the gases, the current paper considers flowmeters whose flow rate indication does not involve any gas property. This paper firstly illustrates the ill condition for the combination of venturi meter and laminar flowmeters. The paper then discusses the simultaneous measurement of flow rate and mole fractions by flowmeter combinations: an ultrasonic flowmeter and a venturi meter, an ultrasonic flowmeter and a laminar flowmeter. Experiments are conducted for a mixture of argon and air. When a venturi meter and a laminar flowmeter are used, the equations to evaluate the gas mixture ratio become an ill-conditioned system, and hence the evaluated mixture ratio shows a considerable error. On the other hand, the combination of an ultrasonic flowmeter and a laminar flowmeter detects the gas mixture ratio with proper accuracy.

  1. Cryogenic Clamp-on Ultrasonic Flowmeters using Single Crystal Piezoelectric Transducers Project

    National Aeronautics and Space Administration — Clamp-on ultrasound cryogenic flowmeters using single crystal piezoelectric transducers are proposed to enable reliable, accurate cryogenic instrumentation needs in...

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

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

  3. Using Coriolis Mass Flowmeter for Wet Gas Metering

    Geng, Y. F.; Yeung, Hoi; Cao, Yi; Xing, L. C.; Zhu, H; Drahm, W.

    2010-01-01

    Established wet gas metering techniques are typically based on differential pressure devices, and their measurement accuracy is still unsatisfactory to natural gas industry. Coriolis mass flowmeter (CMF) is the most superior flow measurement technology at now, it can provide mass flowrate and density output simultaneously. Putting CMF into wet gas metering may be a reasonable and high accuracy solution to natural gas industry demands. The problems and advantages of CMF in ga...

  4. A vortex-shedding flowmeter based on IPMCs

    Di Pasquale, Giovanna; Graziani, Salvatore; Pollicino, Antonino; Strazzeri, Salvatore

    2016-01-01

    Ionic polymer-metal composites (IPMCs) are electroactive polymers that can be used both as sensors and actuators. They have been demonstrated for many potential applications, in wet and underwater environments. Applications in fields such as biomimetics, robotics, and aerospace, just to mention a few, have been proposed. In this paper, the sensing nature of IPMCs is used to develop a flowmeter based on the vortex shedding phenomenon. The system is described, and a model is proposed and verified. A setup has been realized, and data have been acquired for many working conditions. The performance of the sensing system has been investigated by using acquired experimental data. Water flux velocities in the range [0.38, 2.83] m s-1 have been investigated. This working range is comparable with ranges claimed for established technologies. Results show the suitability of the proposed system to work as a flowmeter. The proposed transducer is suitable for envisaged post-silicon applications, where the use of IPMCs gives the opportunity to realize a new generating polymeric flowmeter. This has potential applications in fields where properties of IPMCs such as low cost, usability, and disposability are relevant.

  5. A newly developed borehole flowmeter technology for heterogeneous aquifers

    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 σlnK 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.)

  6. Full report of laser doppler velocimetry (Het-V) data, results , and analysis for pRad shot 0632

    Tupa, Dale [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tainter, Amy Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-21

    This was a collaborative shot with AWE investigators Paul Willis-Patel, David Bell, Seth Grant, David Tarr, and James Richley. The shot was assembled in Los Alamos, after which David Bell set up the probe holder and finalized the alignment. The probe holder location and configuration was modified from previous years to make room for the laser illuminated visible imaging diagnostic. The LANL pRad PDV team was Dale Tupa, Amy Tainter, and Patrick Medina. This shot had three PDV probes: one aimed at the center, one aimed at a feature, one aimed at the reverse side of the shot. The shot also had 9 points of a spectroscopy diagnostic. The pRad team helped set up and field the spectroscopy, but did not help with any data analysis. (The support documentation for the PDV results includes a timing map for the spectroscopy.) Please direct questions on the velocimetry to Dale Tupa or Amy Tainter. The shot radiographs were classified, but the data from the optical diagnostics are not.

  7. Single fiber, laser Doppler flowmetry (LDF) for detecting muscle microcirculation in the low leg and its technique improvement

    Cai, Hongming; Oberg, P. Ake; Rohman, Hakan; Larsson, Sven-Erik

    1995-02-01

    Percutaneous, single fiber LDF of 632.8 nm (He-Ne) is used for continuous recording of low leg muscle microcirculation. An optical fiber (0 equals 0.5 mm) was placed inside the tibialis ant. muscle 10 cm below the knee joint via a plastic cannula (0 equals 1.0 mm) and using local anaesthesia of the skin. The LDF is sampled continuously by the on-line PC computer one minute before, three minutes during and for four minutes after tourniquet occlusion. Twelve healthy, non-smoking men were examined. The reactive hyperaemia and the flux reactive time after release of tourniquet was examined successfully. To get better signal-to-noise ration and deeper detected volume in the muscle, the optical characteristics of ordinary fiber tips and modified spherical and `pear'-type ends were studied. Compared with the system of 632.8 nm, a new optical system with a laser diode of 790 nm was developed. A PC computer with DSP card was used for all the signal processing in the new system.

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

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

  9. Re-Normalization Method of Doppler Lidar Signal for Error Reduction

    In this paper, we presented a re-normalization method for the fluctuations of Doppler signals from the various noises mainly due to the frequency locking error for a Doppler lidar system. For the Doppler lidar system, we used an injection-seeded pulsed Nd:YAG laser as the transmitter and an iodine filter as the Doppler frequency discriminator. For the Doppler frequency shift measurement, the transmission ratio using the injection-seeded laser is locked to stabilize the frequency. If the frequency locking system is not perfect, the Doppler signal has some error due to the frequency locking error. The re-normalization process of the Doppler signals was performed to reduce this error using an additional laser beam to an Iodine cell. We confirmed that the renormalized Doppler signal shows the stable experimental data much more than that of the averaged Doppler signal using our calibration method, the reduced standard deviation was 4.838 Χ 10-3

  10. Study of the functional state of peripheral vessels in fingers of rheumatological patients by means of laser Doppler flowmetry and cutaneous thermometry measurements

    Zherebtsova, Angelina I.; Zherebtsov, Evgeny A.; Dunaev, Andrey V.; Podmasteryev, Konstantin V.; Pilipenko, Olga V.; Krupatkin, Alexander I.; Khakhicheva, Lyudmila S.; Muradyan, Vadim F.

    2016-04-01

    Vasospastic disorders are a common class of rheumatic disease. These include syndromes such as vegetative dystonia, Raynaud's syndrome, vibration disease and rheumatoid arthritis among others. The aim of this work is to develop an original method of diagnosing the functional state of peripheral vessels of the fingers, based on the simultaneous recording of LDF- and thermograms during the occlusion test, for determining vascular disorders of rheumatological patients. A diagnostic method was developed for assessing the functional state of the peripheral vessels of fingers, based on carrying out occlusion test in a thermally stabilized environment, with simultaneous recording of signals of laser Doppler flowmetry and skin thermometry. To verify the diagnostic value of the proposed method, a series of experiments were carried out on 41 rheumatological patients: 5 male and 36 females (average age 56.0+/-12.2 years). The most common diagnoses in the patient group were rheumatoid arthritis, arthrosis, gout and systemic lupus erythematosus. The laser analyser of blood microcirculation "LAKK-02" (SPE "LAZMA" Ltd, Russia) and a custom developed multi-channel thermometry device for low inertia thermometry were used for experimental measurements. The measurements of cutaneous temperature and the index of microcirculation were performed on the distal phalanx of the third finger of the right hand. Occlusion tests were performed with water baths at 25 and 42 °C and a tonometer cuff with a pressure of 200-220 mmHg for 3 min on the upper arm. The results of experimental studies are presented and interpreted. These data indicate a violation of the blood supply regulation in the form of a pronounced tendency towards microvascular vasoconstriction in the fingers. Thus, the response displaying a tendency toward angiospasm among patients in the rheumatological diseases profile group was observed mainly in the most severe cases (49 % of this group). The prospects of the developed

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

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

    2014-12-01

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

  12. Time delay estimation in the ultrasonic flowmeter in the oil well

    Sun, Jian; Lin, Weijun; Zhang, Chengyu; Shen, Zhihui; Zhang, Hailan

    2010-01-01

    A new prototype of ultrasonic flowmeter used in the oil well is presented. The flowmeter depends on the time delay between the propagating times of the downstream and upstream ultrasonic pulses. The ultrasonic passageway is slanted to prevent the disadvantage introduced by the high viscosity of the oil. Two method of time delay estimation: threshold and cross-correlation are both studied and realized.

  13. Actual flow calibration of a feedwater flowmeter using a high Reynolds number facility at NMIJ

    The results of calibration tests of the feedwater flowrate of ultrasonic flowmeters used in a nuclear power plant for variety of upstream conditions obtained using the new high Reynolds number calibration facility at NMIJ are described. In this examination, the measurements are performed for five pattern pipe layouts with one or two elbows. The flow conditioners installed upstream of the flowmeter are the tube bundle type and the Mitsubishi, which are normally used in nuclear power plants. The calibration result for each flowmeter are largely different for each flow conditioner and each upstream pipe layout, except in some special cases. Moreover, the trend of the correction factor with Reynolds number is not uniform for each case. Furthermore, some differences were observed for individual flowmeters. It is recommended that the feedwater flowmeter, especially when used to perform measurement uncertainty recapture, is calibrated based on the actual pipe layout and the Reynolds number corresponding to the actual nuclear power plant conditions.

  14. Actual flow calibration of a feedwater flowmeter using a high Reynolds number facility at NMIJ

    Furuichi, Noriyuki [Fluid Flow Division, National Metrology Institute of Japan, AIST, Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, 305-8563 (Japan)], E-mail: furuichi.noriyuki@aist.go.jp; Terao, Yoshiya [Fluid Flow Division, National Metrology Institute of Japan, AIST, Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, 305-8563 (Japan)], E-mail: yterao@ni.aist.go.jp; Takamoto, Masaki [Fluid Flow Division, National Metrology Institute of Japan, AIST, Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, 305-8563 (Japan)], E-mail: m.takamoto@nifty.ne.jp

    2009-07-15

    The results of calibration tests of the feedwater flowrate of ultrasonic flowmeters used in a nuclear power plant for variety of upstream conditions obtained using the new high Reynolds number calibration facility at NMIJ are described. In this examination, the measurements are performed for five pattern pipe layouts with one or two elbows. The flow conditioners installed upstream of the flowmeter are the tube bundle type and the Mitsubishi, which are normally used in nuclear power plants. The calibration result for each flowmeter are largely different for each flow conditioner and each upstream pipe layout, except in some special cases. Moreover, the trend of the correction factor with Reynolds number is not uniform for each case. Furthermore, some differences were observed for individual flowmeters. It is recommended that the feedwater flowmeter, especially when used to perform measurement uncertainty recapture, is calibrated based on the actual pipe layout and the Reynolds number corresponding to the actual nuclear power plant conditions.

  15. Development of a wide range vortex shedding flowmeter for high temperature helium gas

    Baker, S.P.; Ennis, R.M. Jr.; Herndon, P.G.

    1981-07-01

    A flowmeter was required to measure recirculating helium gas flow over a wide range of conditions in a gas-cooled fast reactor (GCFR) core flow simulator, the ORNL Core Flow Test Loop (CFTL). The flow measurement requirements of the CFTL exceeded the proven performance of any single conventional flowmeter. Therefore, a special purpose vortex shedding flowmeter (VSFM) was developed. A single flowmeter capable of meeting all the CFTL requirements would provide significant economic and performance advantages in the operation of the loop. The development, conceptual design, and final design of a modified VSFM are described. The results of extensive flow calibration of the flowmeter at the Colorado Engineering Experiment Station (CEES) are presented. The report closes with recommendations for application of the VSFM to the CFTL and for future development work.

  16. Development of a wide range vortex shedding flowmeter for high temperature helium gas

    A flowmeter was required to measure recirculating helium gas flow over a wide range of conditions in a gas-cooled fast reactor (GCFR) core flow simulator, the ORNL Core Flow Test Loop (CFTL). The flow measurement requirements of the CFTL exceeded the proven performance of any single conventional flowmeter. Therefore, a special purpose vortex shedding flowmeter (VSFM) was developed. A single flowmeter capable of meeting all the CFTL requirements would provide significant economic and performance advantages in the operation of the loop. The development, conceptual design, and final design of a modified VSFM are described. The results of extensive flow calibration of the flowmeter at the Colorado Engineering Experiment Station (CEES) are presented. The report closes with recommendations for application of the VSFM to the CFTL and for future development work

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

    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 μm. 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

  18. Evaluation of several ultrasonic flowmeter transducers in cryogenic environment

    Moughon, W. C.

    1981-04-01

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

  19. Experimental investigation into the ultrasonic correlation flowmeter performance

    The results of studies on optimizing the parameters of ultrasonic correlation flowmeter are considered. The applied technique for measuring flow rate is based on determination of the shift between signals of two piezoelectric transducers, located along the flow. Time shift is determined by calculation of mutual correlation function and detection of its maximum on time axis. Coolant rate in this case equals to the ratio of the distance between transducers to transport lag. Factors which determine the choice of optimal base distance between transducers, are distinguished

  20. Application of Common Flowmeters%常见流量计的应用

    田野; 王岳; 郭士欢; 刘勇峰; 胡宗柳

    2011-01-01

    Common industrial flowmeters were introduced and classified, such as differential pressure flowmeter, vortex flowmeter, turbine flowmeter, float flow meter, digital target type flowmeter, electromagnetic flowmeter, ultrasonic flowmeter. Characteristics and application scope of different flowmeters were discussed. The differential pressure type flow meter has advantages of simple and stable structure, long life, but has disadvantages of low measuring progress, environmental restriction. Vortex, turbine flowmeter can measure some varieties of media without the parameter influence, but the turbine flowmeter is easily blocked. Float flow meter has the advantages of low pressure loss and stable, can measure low flow medium, but it is not suitable for the measurement of fluid with particle. Digital fluid flowmeter has high temperature resistance characteristic, but has high requirement for medium. Electromagnetic flow meter and target type flowmeter are complementary. Ultrasonic flowmeter can measure various media, but the technology remains to be improved.%简要介绍了一些目前工业上常用的流量计,并将其分类差压式流量计、涡街流量计、涡轮流量计、浮子流量计、数字靶式流量计、电磁流量计、超声波流量计等.每种流量计都各自的特点和适用范围,差压式流量计具有结构简单、结构稳定、使用年限长的优点,但也有测量进度低、受环境限制等缺点.涡街、涡轮流量计可以测量多种介质,不受参数影响,但涡轮流量计易被卡住.浮子流量计有压损小且稳定,可测低流速介质,但不适用于测量有微粒的液体.数字把式流量计具有耐高温的特点,但对介质要求很高.电磁流量计与把式流量计互补.超声波流量计可以测量各种介质,但技术有待于提高.

  1. Rotational Doppler effect in nonlinear optics

    Li, Guixin; Zentgraf, Thomas; Zhang, Shuang

    2016-08-01

    The translational Doppler effect of electromagnetic and sound waves has been successfully applied in measurements of the speed and direction of vehicles, astronomical objects and blood flow in human bodies, and for the Global Positioning System. The Doppler effect plays a key role for some important quantum phenomena such as the broadened emission spectra of atoms and has benefited cooling and trapping of atoms with laser light. Despite numerous successful applications of the translational Doppler effect, it fails to measure the rotation frequency of a spinning object when the probing wave propagates along its rotation axis. This constraint was circumvented by deploying the angular momentum of electromagnetic waves--the so-called rotational Doppler effect. Here, we report on the demonstration of rotational Doppler shift in nonlinear optics. The Doppler frequency shift is determined for the second harmonic generation of a circularly polarized beam passing through a spinning nonlinear optical crystal with three-fold rotational symmetry. We find that the second harmonic generation signal with circular polarization opposite to that of the fundamental beam experiences a Doppler shift of three times the rotation frequency of the optical crystal. This demonstration is of fundamental significance in nonlinear optics, as it provides us with insight into the interaction of light with moving media in the nonlinear optical regime.

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

    Ozge Sahin

    2007-01-01

    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.

  3. Arm locking with Doppler estimation errors

    Yu Yinan; Wand, Vinzenz; Mitryk, Shawn; Mueller, Guido, E-mail: yinan@phys.ufl.ed [Department of Physics, University of Florida, Gainesville, FL 32611 (United States)

    2010-05-01

    At the University of Florida we developed the University of Florida LISA Interferometer Simulator (UFLIS) in order to study LISA interferometry with hardware in the loop at a system level. One of the proposed laser frequency stabilization techniques in LISA is arm locking. Arm locking uses an adequately filtered linear combination of the LISA arm signals as a frequency reference. We will report about experiments in which we demonstrated arm locking using UFLIS. During these experiments we also discovered a problem associated with the Doppler shift of the return beam. The initial arm locking publications assumed that this Doppler shift can perfectly be subtracted inside the phasemeter or adds an insignificant offset to the sensor signal. However, the remaining Doppler knowledge error will cause a constant change in the laser frequency if unaccounted for. Several ways to circumvent this problem have been identified. We performed detailed simulations and started preliminary experiments to verify the performance of the proposed new controller designs.

  4. Research on the optical fiber gas flowmeters based on intermodal interference

    Zhao, Yong; Hu, Hai-feng; Bi, Dan-juan; Yang, Yang

    2016-07-01

    In this work, a self-heating type optical fiber flowmeter with high sensitivity was proposed. The core-offset fiber structures were employed to couple a part of signal light into the fiber cladding layer, and the other part of light still propagated in the core layer. The intermodal interference between the two parts of light happened when the cladding modes were coupled back into core layer. Meanwhile, the high power laser was also introduced into fiber to heat the silver film coated on the surface of the cladding layer. When the cool gas flow passed, the temperature of the sensor probe decreased due to the heat transfer process. Because of the thermo-optic effect in the fiber, interference spectrum could be shifted when the temperature was changed. The experimental results showed the resolution of the proposed sensor was 2×10-2 m/s in the region of 0-8 m/s. The highest sensitivity could achieve 1537 pm/(m/s).

  5. Doppler-free magnetic optical activity

    Giraud-Cotton, S.; Kaftandjian, V.P.; Talin, B.

    1980-01-01

    The theory of Doppler-free magnetic optical activity associated with a single absorption line is presented. The transmission of tunable laser light, linearly polarized, through a dilute gaseous medium along a steady magnetic field is studied in the presence of a second counterpropagating saturating laser. The third order non linear susceptibility is calculated for a two-level system exhibiting a normal Zeeman effect, with arbitrary J values.

  6. Active ultrasonic cross-correlation flowmeters for mixed-phase pipe flows

    Sheen, S. H.; Raptis, A. C.

    Two ultrasonic flowmeters which employ the active cross-correlation technique and use a simple clamp-on transducer arrangement are discussed. The flowmeter for solid/liquid flows was tested over a wide range of coal concentration in water and oil. The measured velocity based on the peak position of the cross-correlation function is consistently higher by about 15% than the average velocity measured by flow diversion. The origin of the difference results mainly from the flow velocity profiles and the transit-time probability distribution. The flowmeter that can measure particle velocity in a solid/gas flow requires acoustic decoupling arrangement between two sensing stations. The measured velocity is mainly associated with the particles near the wall. Performance of both flowmeters is presented.

  7. Ceramic materials for primary loop magnetic flowmeters at nuclear power plants

    Nunn, Stephen D.; Holcomb, David E. [Oak Ridge National Laboratory, Oak Ridge (United States); Chung, Chong Eun; Moon, Byung Soo [Korea Atomic Energy Research Institute, Taejeon (Korea, Republic of); Miller, Don W. [The Ohio State University, Ohio (United States)

    2005-11-15

    Light-water cooled nuclear power plants (NPPs) use primary coolant flow measurements in their reactor thermal power determination. As such, flow measurements are important from both safety and power production perspectives. Flowmeter uncertainty thus remains a significant concern to safe and efficient NPP operation. Magnetic flowmeters are the most commonly deployed modern flowmeter and are most applicable to situations requiring high accuracy measurement of high velocity liquid flows in large pipes-a situation that closely matches NPP primary flow. They have not previously been applied to NPPs because of the environmental sensitivity of currently available component materials. The technical focus of this project was on developing, fabricating, and then assessing the environmental survivability of the ruggedized components required to apply magnetic flowmeter technology to primary coolant loops of NPPs.

  8. Ceramic materials for primary loop magnetic flowmeters at nuclear power plants

    Light-water cooled nuclear power plants (NPPs) use primary coolant flow measurements in their reactor thermal power determination. As such, flow measurements are important from both safety and power production perspectives. Flowmeter uncertainty thus remains a significant concern to safe and efficient NPP operation. Magnetic flowmeters are the most commonly deployed modern flowmeter and are most applicable to situations requiring high accuracy measurement of high velocity liquid flows in large pipes-a situation that closely matches NPP primary flow. They have not previously been applied to NPPs because of the environmental sensitivity of currently available component materials. The technical focus of this project was on developing, fabricating, and then assessing the environmental survivability of the ruggedized components required to apply magnetic flowmeter technology to primary coolant loops of NPPs

  9. Two-step Doppler cooling of a three-level ladder system with an intermediate metastable level

    Champenois, Caroline; Hagel, Gaetan; Knoop, Martina; Houssin, Marie; Zumsteg, Cedric; Vedel, Fernande; Drewsen, Michael

    2007-01-01

    Doppler laser cooling of a three-level ladder system using two near-resonant laser fields is analyzed in the case of the intermediate level being metastable while the upper level is short-lived. Analytical as well as numerical results for e.g. obtainable scattering rates and achievable temperatures are presented. When appropriate, comparisons with two-level single photon Doppler laser cooling is made. These results are relevant to recent experimental Doppler laser cooling investigations addre...

  10. Vortex shedding flowmeters for liquids at high flow velocities

    Siegwarth, J. D.

    1985-01-01

    A number of vortex shedding flowmeter designs for flow measurements in liquid oxygen ducts on the space shuttle main engines have been tested in a high head water flow test facility. The results have shown that a vortex shedding element or vane spanning the duct can give a linear response to an average flow velocity of 46 m/s (150 ft/s) in a 1 1/2 inch nominal (41 mm actual) diameter duct while a vane partially spanning the duct can give a linear response to velocities exceeding 55 m/s (180 ft/s). The maximum pressure drops across the flow sensing elements extrapolate to less than 0.7 MPa (100 psi) at 56 m/s (184 ft/s) for liquid oxygen. The test results indicate that the vanes probably cannot be scaled up with pipe size, at least not linearly.

  11. Spatial and temporal resolution of a local Lorentz force flowmeter

    Electromagnetic measurement techniques are very promising for accessing the flow properties of liquid melts. We extend one of the recently developed techniques, Lorentz force velocimetry, to the measurement of spatial flow structures close to the wall of the confining container. The sensor we use is called local Lorentz force flowmeter (L2F2). It comprises a small permanent magnet which is attached to a force measurement system. We demonstrate that it is possible to reconstruct the complex flow in the vicinity of the wall of a confined vessel using the L2F2. Additionally, we show with the help of a solid body experiment that the L2F2 responds to temporal changes in the flow in the order of 1 Hz. (paper)

  12. High Resolution Doppler Lidar

    1996-01-01

    This Grant supported the development of an incoherent lidar system to measure winds and aerosols in the lower atmosphere. During this period the following activities occurred: (1) an active feedback system was developed to improve the laser frequency stability; (2) a detailed forward model of the instrument was developed to take into account many subtle effects, such as detector non-linearity; (3) a non-linear least squares inversion method was developed to recover the Doppler shift and aerosol backscatter without requiring assumptions about the molecular component of the signal; (4) a study was done of the effects of systematic errors due to multiple etalon misalignment. It was discovered that even for small offsets and high aerosol loadings, the wind determination can be biased by as much as 1 m/s. The forward model and inversion process were modified to account for this effect; and (5) the lidar measurements were validated using rawinsonde balloon measurements. The measurements were found to be in agreement within 1-2 m/s.

  13. INVESTIGATION OF VORTEX SHEDDING INDUCED HYDRODYNAMIC VIBRATION IN VORTEX STREET FLOWMETER

    2001-01-01

    Vortex street flowmeter has been used in steady flo w measurement for about three decades. The benefits of this type of flowmeter i nclude high accuracy,good linearty,wide measuring range,and excellent reliabilit y. However,in unsteady flow measurement,the pressure disturbance as well as the noise from the system or surrounding can reduce the signal-to-noise ra tio of the flowmeter seriously. Aimed to use vortex street flowmeters in unstea dy flow measurement,the characteristics of the vortex shedding induced hydrodyna mic vibration around the prism bluff body in a vortex street flowmeter are inves tigated numerically and by expriments. The results show that the hydrodynamic vibrations with 180° phase shift occur at the axisymmetric points of the channe l around the bluff body. The most intense vibration occurs at the points on the lateral faces close to the base of the prism. The results provide therefore a useful reference for developing an anti-interference vortex flowmeter using the differential sensing technique.

  14. Clinical Doppler ultrasound

    The authors begin with the basics: how Doppler signals are formed, reflected, and refracted - and how those facts apply to clinical practice; anatomy (blood and blood flow), the Doppler equation (explained from a radiologic, rather than a mathematical, perspective); and approaches to Doppler signal production. The available methods of signal processing - including audio, multifilter analysis, zero-crossing detection, autocorrelation, and the Fast Fourier Transform, as well as more sophisticated techniques of duplex and color flow imaging - are covered with an eye to helping the ultrasonographer obtain the most reliable and artifact-free information from every Doppler reading

  15. Flow Measurement Model of Ultrasonic Flowmeter for Gas-Liquid Two-Phase Stratified and Annular Flows

    Lanchang Xing; Chenquan Hua; Hao Zhu; Wolfgang Drahm

    2014-01-01

    An error correction model for ultrasonic gas flowmeter was proposed to explore the potential of an ultrasonic flowmeter for metering gas-liquid stratified and annular flows. The gas and liquid mass flowrates could be obtained provided that the gas quality and physical prosperities were known. A single-path ultrasonic flowmeter was investigated and the error of the apparent volumetric flowrate was considered as mainly resulting from the shrinkage of the gas flow path due to the presence of a l...

  16. Design and implementation of a smartphone-based portable ultrasound pulsed-wave Doppler device for blood flow measurement.

    Huang, Chih-Chung; Lee, Po-Yang; Chen, Pay-Yu; Liu, Ting-Yu

    2012-01-01

    Blood flow measurement using Doppler ultrasound has become a useful tool for diagnosing cardiovascular diseases and as a physiological monitor. Recently, pocket-sized ultrasound scanners have been introduced for portable diagnosis. The present paper reports the implementation of a portable ultrasound pulsed-wave (PW) Doppler flowmeter using a smartphone. A 10-MHz ultrasonic surface transducer was designed for the dynamic monitoring of blood flow velocity. The directional baseband Doppler shift signals were obtained using a portable analog circuit system. After hardware processing, the Doppler signals were fed directly to a smartphone for Doppler spectrogram analysis and display in real time. To the best of our knowledge, this is the first report of the use of this system for medical ultrasound Doppler signal processing. A Couette flow phantom, consisting of two parallel disks with a 2-mm gap, was used to evaluate and calibrate the device. Doppler spectrograms of porcine blood flow were measured using this stand-alone portable device under the pulsatile condition. Subsequently, in vivo portable system verification was performed by measuring the arterial blood flow of a rat and comparing the results with the measurement from a commercial ultrasound duplex scanner. All of the results demonstrated the potential for using a smartphone as a novel embedded system for portable medical ultrasound applications. PMID:22293750

  17. Realization of a multipath ultrasonic gas flowmeter based on transit-time technique.

    Chen, Qiang; Li, Weihua; Wu, Jiangtao

    2014-01-01

    A microcomputer-based ultrasonic gas flowmeter with transit-time method is presented. Modules of the flowmeter are designed systematically, including the acoustic path arrangement, ultrasound emission and reception module, transit-time measurement module, the software and so on. Four 200 kHz transducers forming two acoustic paths are used to send and receive ultrasound simultaneously. The synchronization of the transducers can eliminate the influence caused by the inherent switch time in simple chord flowmeter. The distribution of the acoustic paths on the mechanical apparatus follows the Tailored integration, which could reduce the inherent error by 2-3% compared with the Gaussian integration commonly used in the ultrasonic flowmeter now. This work also develops timing modules to determine the flight time of the acoustic signal. The timing mechanism is different from the traditional method. The timing circuit here adopts high capability chip TDC-GP2, with the typical resolution of 50 ps. The software of Labview is used to receive data from the circuit and calculate the gas flow value. Finally, the two paths flowmeter has been calibrated and validated on the test facilities for air flow in Shaanxi Institute of Measurement & Testing. PMID:23809902

  18. Theoretical and experimental investigations of flow pulsation effects in Coriolis mass flowmeters

    Svete, A.; Kutin, J.; Bobovnik, G.; Bajsić, I.

    2015-09-01

    An understanding of the effects of flow pulsations on the dynamic behavior of Coriolis flowmeters is very important for their further development. In order to determine the phase difference between the vibrational signals, which represents the basic measurement effect of Coriolis flowmeters, there are many methods that include the proper filtering of all the signal components, except those with frequencies close to the drive frequency. Therefore, an understanding of the phenomenon of exciting the meter at its first natural frequency is very important. The results of a simple, linear, two-degree-of-freedom, lumped-parameter, dynamic model of a flowmeter show that the flow pulsations can degrade the accuracy of such a flowmeter as a result of indirect excitations of the measuring tube at the first natural frequency through the second-order perturbations by means of the Coriolis forces induced in pulsating flow conditions. In order to experimentally investigate these flow pulsation effects, a prototype of a straight-tube Coriolis mass flowmeter was developed to enable the processing of the response signals logged directly from the flow tube's sensors with the dual quadrature demodulation method, and therefore to provide the information available within the phase-difference data. The experimental results show that the flow pulsations upset the meter at its first natural frequency indirectly, as well as directly at the frequency of the pulsations due to the geometric imperfections of the measuring tube.

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

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

    2010-08-15

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

  20. Optics and lasers

    1976-01-01

    Report describes twenty-seven optical concepts developed for holographic viewing, spectral transmission, and film camera technology. Articles include developments in laser-Doppler systems, laser beam deflection controls, X-ray photography, and camera components.

  1. Development of a Digital and Battery-Free Smart Flowmeter

    Wang Song Hao

    2014-06-01

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

  2. Electromagnetic Borehole Flowmeter Testing in R-Area

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

  3. Series Supply of Cryogenic Venturi Flowmeters for the ITER Project

    André, J.; Poncet, J. M.; Ercolani, E.; Clayton, N.; Journeaux, J. Y.

    2015-12-01

    In the framework of the ITER project, the CEA-SBT has been contracted to supply 277 venturi tube flowmeters to measure the distribution of helium in the superconducting magnets of the ITER tokamak. Six sizes of venturi tube have been designed so as to span a measurable helium flowrate range from 0.1 g/s to 400g/s. They operate, in nominal conditions, either at 4K or at 300K, and in a nuclear and magnetic environment. Due to the cryogenic conditions and the large number of venturi tubes to be supplied, an individual calibration of each venturi tube would be too expensive and time consuming. Studies have been performed to produce a design which will offer high repeatability in manufacture, reduce the geometrical uncertainties and improve the final helium flowrate measurement accuracy. On the instrumentation side, technologies for differential and absolute pressure transducers able to operate in applied magnetic fields need to be identified and validated. The complete helium mass flow measurement chain will be qualified in four test benches: - A helium loop at room temperature to insure the qualification of a statistically relevant number of venturi tubes operating at 300K.- A supercritical helium loop for the qualification of venturi tubes operating at cryogenic temperature (a modification to the HELIOS test bench). - A dedicated vacuum vessel to check the helium leak tightness of all the venturi tubes. - A magnetic test bench to qualify different technologies of pressure transducer in applied magnetic fields up to 100mT.

  4. Experimental Assessment of a Variable Orifice Flowmeter for Respiratory Monitoring

    Giuseppe Tardi

    2015-01-01

    Full Text Available Accurate measurement of gas exchanges is essential in mechanical ventilation and in respiratory monitoring. Among the large number of commercial flowmeters, only few kinds of sensors are used in these fields. Among them, variable orifice meters (VOMs show some valuable characteristics, such as linearity, good dynamic response, and low cost. This paper presents the characterization of a commercial VOM intended for application in respiratory monitoring. Firstly, two nominally identical VOMs were calibrated within ±10 L·min−1, to assess their metrological properties. Furthermore, experiments were performed by humidifying the air, to evaluate the influence of vapor condensation on sensor’s performances. The condensation influence was investigated during two long lasting trials (i.e., 4 hours by delivering 4 L·min−1 and 8 L·min−1. Data show that the two VOMs’ responses are linear and their response is comparable (sensitivity difference of 1.4%, RMSE of 1.50 Pa; their discrimination threshold is <0.5 L·min−1, and the settling time is about 66 ms. The condensation within the VOM causes a negligible change in sensor sensitivity and a very slight deterioration of precision. The good static and dynamic properties and the low influence of condensation on sensor’s response make this VOM suitable for applications in respiratory function monitoring.

  5. Experimental investigations of the parameters of an ultrasonic correlation flowmeter

    An important condition for accident-free operation of power plants is that the flow rate of the coolant must be monitored. The most promising methods for measuring the flow rate are contact-free methods, which permit measurements without destroying the integrity of the pipe lines (housing) in the nuclear power plant. In the development of contact-free methods for measuring the flow rate increasingly greater attention is being devoted to ultrasonic correlation flowmeters. The ultrasonic correlation method for measuring the flow rate is based on determining the shift between the signals from two piezoelectric sensors placed in the flow. The time shift is determined by the calculation of the mutual correlation function and finding its maximum on the time axis. The velocity of the coolant, in this case, equals the ratio of the distance between the sensors to the transport delay. The practical implementation of this method requires an optimal choice of parameters of the piezoelectric sensors and characteristics of the secondary apparatus. The paper proposes a mathematical model to optimize parameters

  6. Ultrasonic colour Doppler imaging

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

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue...... weaknesses, perhaps the greatest being that in conventional systems, the velocities measured and thus displayed are the components of the flow velocity directly towards or away from the transducer, while ideally the method would give information about the magnitude and direction of the three-dimensional flow...... vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new...

  7. Characteristics of multipath ultrasonic flowmeter installed upstream and downstream of flow disturbance factors-Contraction, Expansion, and Tee Pipe

    Lee, Dong Keun; Cho, Yong [Korea Water Resources Corporation, Daejeon (Korea, Republic of)

    2012-08-15

    Multipath ultrasonic flowmeters are increasingly being used for the purpose of accurate flow measurement. However, an installation standard has not yet been established for these flowmeters, and this can cause considerable confusion during field installation. There is a need for a minimum straight run to ensure the measurement accuracy of a flowmeter installed upstream and downstream of flow disturbance factors expansion, contraction, and tee pipes. Experiments were performed by using multipath flowmeters that have less than {+-}0.5% accuracy 4 paths 1 unit and 2 paths 1 unit are of foreign make, whereas 5 paths 2 units are of domestic make to determine the straight run under the above conditions. We carried out experiments repeatedly by considering a straight run, velocity, and suggested installation standards for a multipath ultrasonic flowmeter that satisfies the tolerance limits.

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

    Lee, Dong Keun; Cho, Yong [Korea Water Resources Corporation, Daejeon (Korea, Republic of)

    2011-08-15

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

  9. Cosmology with Doppler Lensing

    Bacon, David; Andrianomena, Sambatra; Clarkson, Chris; Bolejko, C.; Maartens, Roy

    2014-01-01

    Doppler lensing is the apparent change in object size and magnitude due to peculiar velocities. Objects falling into an overdensity appear larger on its near side, and smaller on its far side, than typical objects at the same redshifts. This effect dominates over the usual gravitational lensing magnification at low redshift. Doppler lensing is a promising new probe of cosmology, and we explore in detail how to utilize the effect with forthcoming surveys. We present cosmological simulations of...

  10. Rotational Doppler Effect

    Halder, Amit

    2002-01-01

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

  11. An additional uncertainty of the throughput generated by the constant pressure gas flowmeter

    Peksa, L.; Gronych, T.; Řepa, P.; Wild, J.; Tesař, J.; Pražák, D.; Krajíček, Z.; Vičar, M.

    2008-03-01

    The lower range limit of constant pressure gas flowmeters is about 10-8 Pa×m3/s. Detrimental gas throughputs caused by leaks and gassing from surfaces prevent from its decrease. Even if the flowmeter is entirely vacuum tight the throughput caused by the outgassing from surfaces can be sufficiently reduced only by pumping at elevated temperature. It can be performed with the flowmeters using directly driven bellows or diaphragm bellows in the volume displacers. Despite it, the lower range limit can hardly be decreased more than several ten times with up to now known designs. An additional uncertainty caused by the difference in pressure at the initial and final instant of measurement will increase at generating small throughputs to the extent that it will kill the measurement.

  12. An additional uncertainty of the throughput generated by the constant pressure gas flowmeter

    The lower range limit of constant pressure gas flowmeters is about 10-8 Paxm3/s. Detrimental gas throughputs caused by leaks and gassing from surfaces prevent from its decrease. Even if the flowmeter is entirely vacuum tight the throughput caused by the outgassing from surfaces can be sufficiently reduced only by pumping at elevated temperature. It can be performed with the flowmeters using directly driven bellows or diaphragm bellows in the volume displacers. Despite it, the lower range limit can hardly be decreased more than several ten times with up to now known designs. An additional uncertainty caused by the difference in pressure at the initial and final instant of measurement will increase at generating small throughputs to the extent that it will kill the measurement

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

    Wang, X. F.; Tang, Z. A.

    2011-04-01

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

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

    Wang, X. F.; Tang, Z. A. [Department of Electronic Science and Technology, Dalian University of Technology, Dalian, 116023 (China)

    2011-04-15

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

  15. Calibration of an ultrasonic flowmeter and investigation of its behavior under given mounting conditions

    Kalkhof, H. G.; Hajek, W.

    1985-01-01

    An ultrasonic flowmeter equipped with three movable detectors was calibrated on a water meter test stand and tested under mounting conditions similar to the definitive mounting in the primary cooling circuit of an experimental nuclear reactor. Measuring errors are found to be 0.5%. However, deviations 20% are found when the flowmeter is mounted behind parts distorting the velocity profile in tube, especially by angular momentum. These errors are significantly reduced by the introduction of a flow rectifier which has to be calibrated together with the flowmeter. The magnitude of the deviations between the three measured signals and the magnitude of the measuring signal deviations at constant flow are shown to be influenced by flow perturbations. The measuring signal differences can therefore only be determined during commissioning in the primary cooling circuit.

  16. Wide-range vortex shedding flowmeter for high-temperature helium gas

    The existing design of a commercially available vortex shedding flowmeter (VSFM) was modified and optimized to produce three 4-in. and one 6-in. high-performance VSFMs for measuring helium flow in a gas-cooled fast reactor (GCFR) test loop. The project was undertaken because of the significant economic and performance advantages to be realized by using a single flowmeter capable of covering the 166:1 flow range (at 3500C and 45:1 pressure range) of the tests. A detailed calibration in air and helium at the Colorado Engineering Experiment Station showed an accuracy of +-1% of reading for a 100:1 helium flow range and +-1.75% of reading for a 288:1 flow range in both helium and air. At an extended gas temperature of 4500C, water cooling was necessary for reliable flowmeter operation

  17. A wide-range vortex shedding flowmeter for high temperature helium gas

    The existing design of a commercially available vortex shedding flowmeter (VSFM) was modified and optimized to produce three 4-in. and one 6-in. high performance VSFMs for measuring helium flow in a gas-cooled fast reactor (GCFR) test loop. The project was undertaken because of the significant economic and performance advantages to be realized by using a single flowmeter capable of covering the 166:1 flow range (at 3500C and 45:1 pressure range) of the tests. A detailed calibration in air and helium at the Colorado Engineering Experiment Station showed an accuracy of +.1% of reading for a 100:1 helium flow range and +.1.75% of reading for a 288:1 flow range in both helium and air. At an extended gas temperature of 4500C, water cooling was necessary for reliable flowmeter operation

  18. Wide-range vortex shedding flowmeter for high-temperature helium gas

    Baker, S.P.; Herndon, P.G.; Ennis, R.M. Jr.

    1983-01-01

    The existing design of a commercially available vortex shedding flowmeter (VSFM) was modified and optimized to produce three 4-in. and one 6-in. high-performance VSFMs for measuring helium flow in a gas-cooled fast reactor (GCFR) test loop. The project was undertaken because of the significant economic and performance advantages to be realized by using a single flowmeter capable of covering the 166:1 flow range (at 350/sup 0/C and 45:1 pressure range) of the tests. A detailed calibration in air and helium at the Colorado Engineering Experiment Station showed an accuracy of +-1% of reading for a 100:1 helium flow range and +-1.75% of reading for a 288:1 flow range in both helium and air. At an extended gas temperature of 450/sup 0/C, water cooling was necessary for reliable flowmeter operation.

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

    Paradis, D.; Lefebvre, R.; Morin, R.H.; Gloaguen, E.

    2011-01-01

    Numerical hydrogeological models should ideally be based on the spatial distribution of hydraulic conductivity (K), a property rarely defined on the basis of sufficient data due to the lack of efficient characterization methods. Electromagnetic borehole flowmeter measurements during pumping in uncased wells can effectively provide a continuous vertical distribution of K in consolidated rocks. However, relatively few studies have used the flowmeter in screened wells penetrating unconsolidated aquifers, and tests conducted in gravel-packed wells have shown that flowmeter data may yield misleading results. This paper describes the practical application of flowmeter profiles in direct-push wells to measure K and delineate hydrofacies in heterogeneous unconsolidated aquifers having low-to-moderate K (10-6 to 10-4 m/s). The effect of direct-push well installation on K measurements in unconsolidated deposits is first assessed based on the previous work indicating that such installations minimize disturbance to the aquifer fabric. The installation and development of long-screen wells are then used in a case study validating K profiles from flowmeter tests at high-resolution intervals (15 cm) with K profiles derived from multilevel slug tests between packers at identical intervals. For 119 intervals tested in five different wells, the difference in log K values obtained from the two methods is consistently below 10%. Finally, a graphical approach to the interpretation of flowmeter profiles is proposed to delineate intervals corresponding to distinct hydrofacies, thus providing a method whereby both the scale and magnitude of K contrasts in heterogeneous unconsolidated aquifers may be represented. Journal compilation ?? 2010 National Ground Water Association.

  20. Narrowing of EIT resonance in a Doppler Broadened Medium

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

    2001-01-01

    We derive an analytic expression for the linewidth of EIT resonance in a Doppler broadened system. It is shown here that for relatively low intensity of the driving field the EIT linewidth is proportional to the square root of intensity and is independent of the Doppler width, similar to the laser induced line narrowing effect by Feld and Javan. In the limit of high intensity we recover the usual power broadening case where EIT linewidth is proportional to the intensity and inversely proporti...

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

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

    2014-06-01

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

  2. LISA data analysis: Doppler demodulation

    The orbital motion of the laser interferometer space antenna (LISA) produces amplitude, phase and frequency modulations of a gravitational wave signal. The modulations have the effect of spreading a monochromatic gravitational wave signal across a range of frequencies. The modulations encode useful information about the source location and orientation, but they also have the deleterious effect of spreading a signal across a wide bandwidth, thereby reducing the strength of the signal relative to the instrument noise. We describe a simple method for removing the dominant, Doppler component of the signal modulation. The demodulation reassembles the power from a monochromatic source into a narrow spike and provides a quick way to determine the sky locations and frequencies of the brightest gravitational wave sources

  3. Doppler Lidar for Wind Measurements on Venus

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

    2010-01-01

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

  4. Ultrasonic Doppler Modes

    Tortoli, Piero; Fidanzati, Paolo; Luca, Bassi

    Any US equipment includes Doppler facilities capable of providing information about moving structures inside the human body. In most cases, the primary interest is in the investigation of blood flow dynamics, since this may be helpful for early diagnosis of cardiovascular diseases. However, there is also an increasing interest in tracking the movements of human tissues, since such movements can give an indirect evaluation of their elastic properties, which are valuable indicators of the possible presence of pathologies. This paper aims at presenting an overview of the different ways in which the Doppler technique has been developed and used in medical ultrasound (US), from early continuous wave (CW) systems to advanced pulsed wave (PW) colour-Doppler equipment. In particular, the most important technical features and clinical applications of CW, single-gate PW, multi-gate PW and flow-imaging systems are reviewed. The main signal processing approaches used for detection of Doppler frequencies are described, including time-domain and frequency-domain (spectral) methods, as well as novel strategies like, e.g., harmonic Doppler mode, which have been recently introduced to exploit the benefits of US contrast agents.

  5. Doppler cooling a microsphere

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The scattering force is not limited by saturation, but can be controlled by the incident power. Cooling times on the order of seconds are calculated for a 20 micron diameter silica microsphere trapped within optical tweezers, with a Doppler temperature limit in the microKelvin regime.

  6. Doppler-suuntima-algoritmi

    Rekis, Matti

    2014-01-01

    Doppler-ilmiö aiheuttaa havaitsijan ja signaalilähteen välisen suhteellisen liikkeen seurauksena taajuusvääristymää lähteen alkuperäisestä signaalista. Tämä mm. doppler-siirtymäksi kutsuttu vääristymä voidaan havaita signaalilähteen taajuudessa, aallonpituudessa ja vaiheessa. Doppler-siirtymän suuruuteen ja suuntaan vaikuttaa se, kasvaako vai pieneneekö havaitsijan ja lähteen välinen etäisyys sekä niiden välinen suhteellinen nopeus. Tätä ilmiötä voidaan hyödyntää mm. radiolähettimen paikantam...

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

    Edwin H. Kolodny

    2010-12-01

    Full Text Available Neuromolecular Imaging (NMI based on adsorptive electrochemistry, combined with Dual Laser Doppler Flowmetry (LDF is presented herein to investigate the brain neurochemistry affected by enoxaparin (Lovenox®, an antiplatelet/antithrombotic medication for stroke victims. NMI with miniature biosensors enables neurotransmitter and neuropeptide (NT imaging; each NT is imaged with a response time in milliseconds. A semiderivative electronic reduction circuit images several NT’s selectively and separately within a response time of minutes. Spatial resolution of NMI biosensors is in the range of nanomicrons and electrochemically-induced current ranges are in pico- and nano-amperes. Simultaneously with NMI, the LDF technology presented herein operates on line by illuminating the living brain, in this example, in dorso-striatal neuroanatomic substrates via a laser sensor with low power laser light containing optical fiber light guides. NMI biotechnology with BRODERICK PROBE® biosensors has a distinct advantage over conventional electrochemical methodologies both in novelty of biosensor formulations and on-line imaging capabilities in the biosensor field. NMI with unique biocompatible biosensors precisely images NT in the body, blood and brain of animals and humans using characteristic experimentally derived half-wave potentials driven by oxidative electron transfer. Enoxaparin is a first line clinical treatment prescribed to halt the progression of acute ischemic stroke (AIS. In the present studies, BRODERICK PROBE® laurate biosensors and LDF laser sensors are placed in dorsal striatum (DStr dopaminergic motor neurons in basal ganglia of brain in living animals; basal ganglia influence movement disorders such as those correlated with AIS. The purpose of these studies is to understand what is happening in brain neurochemistry and cerebral blood perfusion after causal AIS by middle cerebral artery occlusion in vivo as well as to understand consequent

  8. Pulse Doppler radar

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  9. Doppler ion program description

    The Doppler spectrometer is a conventional Czerny-Turner grating spectrometer with a 1024 channel multiple detector. Light is dispersed across the detector, and its output yields a spectrum covering approximately 200 A. The width of the spectral peak is directly proportional to the temperature of the emitting ions, and determination of the impurity ion temperature allows one to infer the plasma ion temperature. The Doppler ion software system developed at General Atomic uses a TRACOR Northern 1710-31 and an LSI-11/2. The exact configuration of Doublet III is different from TRACOR Northern systems at other facilities

  10. Doppler Cooling a Microsphere

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The...

  11. Polarimetric Doppler Weather Radar

    Bringi, V. N.; Chandrasekar, V.

    2001-10-01

    This work provides a detailed introduction to the principles of Doppler and polarimetric radar, focusing in particular on their use in the analysis of weather systems. The authors first discuss underlying topics such as electromagnetic scattering, polarization, and wave propagation. They then detail the engineering aspects of pulsed Doppler polarimetric radar, before examining key applications in meteorology and remote sensing. The book is aimed at graduate students of electrical engineering and atmospheric science as well as practitioners involved in the applications of polarimetric radar.

  12. Doppler blood flow indicator

    Byrtus, David

    2014-01-01

    This bachelor´s thesis deals with basis of ultra-acoustics. The project presents basic information about Doppler effect. It describes the methods of processing and analyzing of velocity and direction of blood at doppler’s systems with modulated and unmodulated carrier wave. The project presents the system design of non-directional doppler indicator with unmodulated carrier wave for 8 MHz frequency, generating intensity of ultrasound 100 mW/cm2 and diameter D-shaped transmitting transducer 8 m...

  13. Electromagnetic flowmeter in-situ calibration by the flow fluctuation cross correlation method

    Electromagnetic flowmeters are used widely in the sodium test loops and fast breeder reactor plants, and recognized to be one of the most reliable ones. But it is possible that the electromotive force of the flowmeters decreases by the decrease of magnetic flux density and by the increase of sodium inpurity. From these reasons, there is the cross correlation with flow fluctuation signals as one of the in-situ calibration methods. For the establishment of this method, sodium flow measurement tests were conducted using the 6 inches electromagnetic flowmeter. And for the flow range of 1 ∼ 5 m/s, calibration was confirmed to be possible within the accuracy of ± 4 %. These results were found to be realized under the following conditions; (1) Electrods are settled at the direction of 45 deg from the center of the pipe, (2) Flow fluctuation frequency of 15 ∼ 20 Hz are used by the band pass filter, (3) Distance between electrods is 150 mm, (4) Correction coefficient to the flowmeter output is 1.00. In future, effectiveness of this method would be confirmed for larger flow pipe. (author)

  14. Effect of asymmetric actuator and detector position on Coriolis flowmeter and measured phase shift

    Enz, Stephanie

    2010-01-01

    Coriolis flowmeters (CFM) are forced to vibrate by a periodic excitation usually applied midpipe through an electromagnetic actuator. From hands-on experience with industrial CFMs it appears, that the electromagnetic actuator has to be located as symmetric as possible. For CFM design and trouble-...

  15. Experimental investigation of zero phase shift effects for Coriolis flowmeters due to pipe imperfections

    Enz, Stephanie; Thomsen, Jon Juel; Neumeyer, Stefan

    2011-01-01

    Theoretical investigations of a single, straight, vibrating, fluid-conveying pipe have resulted in simple analytical expressions for the approximate prediction of the spatial shift in vibration phase. The expressions have lead to hypotheses for real Coriolis flowmeters (CFMs). To test these, the ...

  16. Characterization of Preferential Flow Path in Fractured Rock Using Heat-pulse Flowmeter

    Lee, Tsai-Ping; Lin, Ming-Hsuan; Chuang, Po-Yu; Chia, Yeeping

    2015-04-01

    Rigorous thinking on how to dispose radioactive wastes safely is essential to mankind and living environment. The concepts of multiple barriers and deep geologic disposal remain the preferred option to retard the radionuclide migration in most countries. However, the investigation of preferential groundwater flow path in a fractured rock is a challenge to the characterization of potential disposal site. Heat-pulse flowmeter is a developing logging tool for measuring the vertical flow velocity in a borehole under a constant pumping or injection rate and provides a promising direct measurement method for determining the vertical distribution of hydraulic conductivity of formation. As heat-pulse flowmeter is a potential technique to measure low-velocity borehole flow, we adopted it to test the feasibility of detecting permeable fractures. Besides, a new magnetic tracer made by nano-iron particles is developed to identify the possible flow path precisely and to verify the permeable section detected by the heat-pulse flowmeter. The magnetic tracer was received by a magnet array and can also be detected by a sensor of electric conductivity. The test site is located in the Heshe of Taiwan. Eight wells were established in a fractured sandy siltstone for characterizing the fracture network. The test wells are 25 to 45 m depth and opened ranging from 15 to 45 m. Prior to the heat-pulse flowmeter measurement, we also performed surface geological investigation, pumping test, geophysical logging, and salt tracer test. Field measurements using heat-pulse flowmeter were then conducted at a constant pumping rate. The measurement interval is 50 to 100 cm in depth but improved to 25 cm near the relatively permeable zone. Based on the results of heat-pulse flowmeter, several permeable sections were identified. The magnetic tracer tests were then conducted to verify the potential preferential flow pathway between adjacent wells. Test results indicated that water flow in borehole is

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

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

    2011-12-01

    We developed an autonomous electromagnetic flowmeter as part of a cross-hole hydrogeologic experiment using subseafloor borehole observatories (CORKs) that penetrate into the volcanic ocean crust. The cylindrical flowmeter is adapted from a conventional industrial tool and hardened for use at water depths up to 6000 m. In addition, the electronics were modified with a new power controller, and a data logger and communication board was added to enable data storage and long-term, autonomous use for up to eight years. The flowmeter generates a magnetic field and measures a voltage gradient that is created across the orifice as water moves through it. This kind of tool is ideally suited for use in the deep sea, particularly for measuring hydrothermal fluids emanating from the ocean crust, because it requires no moving parts, places no obstructions along the flow path, gives total flow volume as well as instantaneous flow rate, and is highly accurate across a large dynamic range, including bi-directional flow. This flowmeter was deployed on a CORK wellhead using an adapter and ring clamp system located above a 4-inch ball valve. The ball valve can be opened to permit flow (from an overpressured formation) out of the CORK and into the overlying ocean. A polyvinyl chloride "chimney" positioned vertically above the flowmeter is instrumented with autonomous temperature loggers to permit an additional estimate of fluid flow rates with time, based on heat loss during fluid ascent, and to facilitate fluid sampling. Calibration of the new flowmeter was completed in two stages: tank testing using a pump at flow rates of 0.5 to 1.2 L/s, and by lowering the flowmeter on a wireline at sea at rates equivalent to 0.5 to 5.2 L/s. A cross plot of apparent and reference flow rates obtained during calibration indicates a highly linear instrument response. Comparison of instantaneous (once per minute) and integrated (total flow) data collected during calibration indicates good agreement

  18. Doppler-musical instrument

    We propose a possible ultra-high energy resolution backscattering spectrometer optimized to spallation neutron source. A combination of multi monochromator crystal and Doppler drive provides considerable neutron flux, together with the reasonable energy range -30 < E < 30 μeV, even when the ultra-high energy resolution of ΔE∼0.03 μeV is attained. (author)

  19. Comparison of UNL laser imaging and sizing system and a phase/Doppler system for analyzing sprays from a NASA nozzle

    Alexander, Dennis R.

    1988-01-01

    Aerosol spray characterization was done using a P/DPA and a laser imaging/video processing system on a NASA MOD-1 air-assist nozzle being evaluated for use in aircraft icing research. Benchmark tests were performed on monodispersed particles and on the NASA MOD-1 nozzle under identical laboratory operating conditions. The laser imaging/video processing system and the P/DPA showed agreement on calibration tests in monodispersed aerosol sprays of + or - 2.6 microns with a standard deviation of + or - 2.6 microns. Tests were performed on the NASA MOD-1 nozzle on the centerline and radially at one-half inch increments to the outer edge of the spray plume at a distance two feet (0.61 m) downstream from the exit of the nozzle. Comparative results at two operating conditions of the nozzle are presented for the two instruments. For the first case, the deviation in arithmetic mean diameters determined by the two instruments was in a range of 0.1 to 2.8 microns, and the deviation in Sauter mean diameters varied from 0 to 2.2 microns. Operating conditions in the second case were more severe which resulted in the arithmetic mean diameter deviating from 1.4 to 7.1 microns and the deviation in the Sauter mean diameters ranging from 0.4 to 6.7 microns.

  20. The experimental study on Doppler echo signals with different scattering surfaces for velocity measurement

    Wang, Leng-ping; Feng, Di; Ou, Pan; Yang, De-zhao

    2011-06-01

    Laser Doppler velocimetry has the ability to measure speed and surface vibrations non-intrusively with high precision. In this study the Doppler spectrum shift and spectrum broadening of echo signals by moving targets are investigated. The interaction between moving object and the laser beam of laser Doppler velocimetry have been described by varying rotating velocity, the angular velocity, distance and incident facula. By using different scattering surfaces, such as Polytetrafluoroethylene (PTFE) and sandpaper with different grain sizes, the characteristics of echo signals' Doppler spectra have been studied experimentally in detail. The results show that Doppler spectrum distribution is changed with different scattering surfaces. Meanwhile, in order to get a high measuring accuracy, the moving object's scattering characteristics must be considered carefully.

  1. Doppler speedometer for micro-organisms

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

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

    Chung, Chong Eun; Moon, Byung Soo; Hwang, In Koo; Kim, Yong Kyun; Hong, Seok Boong; Kim, Jung Bok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Holcomb, E. David; Nunn, D. Stephen [Oak Ridge National Laboratory, Oak Ridge (Uruguay)

    2005-07-01

    Nuclear power plants are licensed to operate at power levels up to a specified thermal power rating. Safety analyses and evaluations are performed at conditions selected to account for uncertainties in determining thermal power. The NRC in Regulatory Guide 1.49, Rev. 1, December 1973 provides guidance regarding the amount of margin needed to account for uncertainties. Guidance provided in Regulatory Guide 1.49 recommends that analyses and evaluations be made by assuming the thermal power is equal to 1.02 times the licensed thermal power. The reason that analyses should be performed at two percent above the licensed thermal power is to allow for possible instrument errors. A 1% error in a primary loop flow can result in a 1% reduction in the unit net load if the error is in the high direction. In order to avoid errors in the low direction (and exceeding the licensed plant thermal power) a margin is built into the control system. Improved accuracy of the primary flow measurement allows for a reduction of this margin. EPRI has reported that the typical power plant primary flow measurement errors are 3{approx}5%. Primary loop flow measurements are used to determine the core heat rate in PWRs and as such are a basic safety indication. These measurements are conventionally made using flowmeters based on the differential pressure. Differential pressure based on flowmeters have significant, fundamental accuracy limitations as well as having failure modes difficult to diagnose while in service. Magnetic flowmeters offer a potential solution to these limitations. Magnetic flowmeters are highly accurate, respond linearly, and are obstructionless (no fouling; consume no pumping power). Also, the transmitter for magnetic flowmeters can be located remotely (up to hundreds of feet) from the point of the measurement, thus reducing the environmental exposure. The major limitation to the immediate application of magnetic flowmeters to nuclear power plants is the radiation

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

    Nuclear power plants are licensed to operate at power levels up to a specified thermal power rating. Safety analyses and evaluations are performed at conditions selected to account for uncertainties in determining thermal power. The NRC in Regulatory Guide 1.49, Rev. 1, December 1973 provides guidance regarding the amount of margin needed to account for uncertainties. Guidance provided in Regulatory Guide 1.49 recommends that analyses and evaluations be made by assuming the thermal power is equal to 1.02 times the licensed thermal power. The reason that analyses should be performed at two percent above the licensed thermal power is to allow for possible instrument errors. A 1% error in a primary loop flow can result in a 1% reduction in the unit net load if the error is in the high direction. In order to avoid errors in the low direction (and exceeding the licensed plant thermal power) a margin is built into the control system. Improved accuracy of the primary flow measurement allows for a reduction of this margin. EPRI has reported that the typical power plant primary flow measurement errors are 3∼5%. Primary loop flow measurements are used to determine the core heat rate in PWRs and as such are a basic safety indication. These measurements are conventionally made using flowmeters based on the differential pressure. Differential pressure based on flowmeters have significant, fundamental accuracy limitations as well as having failure modes difficult to diagnose while in service. Magnetic flowmeters offer a potential solution to these limitations. Magnetic flowmeters are highly accurate, respond linearly, and are obstructionless (no fouling; consume no pumping power). Also, the transmitter for magnetic flowmeters can be located remotely (up to hundreds of feet) from the point of the measurement, thus reducing the environmental exposure. The major limitation to the immediate application of magnetic flowmeters to nuclear power plants is the radiation sensitivity of

  4. HF Doppler observations

    Kikuchi, T.; Sugiuchi, H.; Ishimine, T.; Maeno, H.; Honma, S.

    1986-12-01

    This paper reports the solar flare and geomagnetic storm effects on the frequency of JJY signals received at Okinawa (f = 15 MHz) and Kokubunji (f = 5 and 8 MHz) during the period of June-September 1982. The increase in the electron density due to solar flares is deduced from the Doppler frequency deviation of 1 Hz as 2 x 10/sup 15/ electrons/m/sub 2/ below the reflection height. The result is in good agreement with the observation of the total electron content by the Faraday rotation measurements. On July 13, 1982, an abrupt increase of 0.8 Hz in frequency followed by a decrease of 0.6 Hz was observed in association with the huge storm sudden commencement. This fact indicates a successive transmission of westward electric field of 1.5 mV/m and eastward electric field of 1.1 mV/m from the outer magnetosphere to the low latitude ionosphere. It is shown that the decreases in Doppler frequency were associated with geomagnetic bays. The strength of the electric field (1.8 mV/m) derived from the Doppler frequency deviation is 20% of that of the electric field which is required to produce ionospheric electric currents responsible for the geomagnetic field variation on the ground. The large amplitude Doppler frequency oscillations of period of 1-1.5 h were observed at Kokubunji and Okinawa with a delay time of 20-25 min during the geomagnetic storm on September 6, 1982. It is suggested that the large-scale TID (Travelling Ionospheric Disturbance) with a phase velocity of 600 m/s and a wavelength of 2000 km is produced at high latitudes and is propagated to low latitudes.

  5. Study Of Topical Anti-Inflammatory Potency And Clinical Efficacy Of Formulations Of Mometasone And Betamethasone By Cutaneous Blood Flow Measurements In Psoriatic Patients Using Laser Doppler Velocimetry

    Mulekar S. V

    1997-01-01

    Full Text Available Laser Doppier Velocimetry (LDV was used to measure cutaneous blood flow (CBF in psoriatic skin lesions to assess the effect of once daily application of Mometasone furoate (MF in a base claimed to possess a “reservoir” effect, as against Betamethasone-17-valarate (BV in a conventional cream base, applied twice daily, for 4 weeks. Bilaterally symmetrical active lesions were studied in 10 psoriatics, at baseline and at the end of 2 and 4 weeks’ treatment. The formulations were also evaluated for topical anti-inflammatory potency in terms of their ability to inhibit the Post-Ischaemic-Reactive-Hyperaemic-Response (PIRHR induced on normal uninvolved skin treated under occlusion. The lesions were also assessed subjectively for clinical Psoriatic Hyperaemia Index (PHI = CBF on lesions/CBF on uninvolved skin: 8.42 + 1.74 & 10.13 + 1.70 correlating with high CPI (9 + 0.50 & 9.1 + 0.51. During treatment with MF or BV, the lesions resolved rapidly, with a concomitant decrease in PHI and CPI (Week 2 : PHI = 3.40 + 0.46 & 5.19 + 1.65, CPI = 4.15 + 0.86& 5.20 + 0.87 and Week 4 : PHI = 1.99 + 0.23 & 2.81 + 0.74 CPI = 2.00 + 0.50 & 2.88 + 0.72 respectively. The two formulations Inhibited PIRHR to same extent (auc/min: Control = 1871 + 399.22, MF = 536.11 + 153.34 & BV = 567.5 + 110.76, indicating equal potency. The results show that pharmaceutical factor such as vehicle can significantly influence the clinical efficacy of corticoids.

  6. Analytical Model of Doppler Spectra of Light Backscattered from Rotating Convex Bodies of Revolution in the Global Cartesian Coordinate System

    GONG Yan-Jun; WU Zhen-Sen; WU Jia-Ji

    2009-01-01

    We present an analytical model of Doppler spectra in backscattering from arbitrary rough convex bodies of revolution rotating around their axes in the global Cartesian coordinate system. This analytical model is applied to analyse Doppler spectra in backscatter from two cones and two cylinders, as well as two ellipsoids of revolution. We numerically analyse the influences of attitude and geometry size of objects on Doppler spectra. The analytical model can give contribution of the surface roughness, attitude and geometry size of convex bodies of revolution to Doppler spectra and may contribute to laser Doppler velocimetry as well as ladar applications.

  7. Wind Measurements with High Energy 2 Micron Coherent Doppler Lidar

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

    2004-01-01

    A coherent Doppler lidar based on an injection seeded Ho:Tm:YLF pulsed laser was developed for wind measurements. A transmitted pulse energy over 75 mJ at 5 Hz repetition rate has been demonstrated. Designs are presented on the laser, injection seeding, receiver, and signal processing subsystems. Sample data of atmospheric measurements are presented including a wind profile extending from the atmospheric boundary layer (ABL) to the free troposphere.

  8. Rotational Doppler velocimetry to probe the angular velocity of spinning microparticles

    Phillips, D.B.; Lee, M P; Speirits, F. C.; Barnett, S. M.; Simpson, S.H.; Lavery, M.P.J.; Padgett, M.J.; Gibson, G. M.

    2014-01-01

    Laser Doppler velocimetry is a technique used to measure linear velocity, ranging from that of exhaust gases to blood flow. A rotational analog of laser Doppler velocimetry was recently demonstrated, using a rotationally symmetric interference pattern to probe the angular velocity of a spinning object. In this work, we demonstrate the use of a diffraction-limited structured illumination pattern to measure the angular velocity of a micron-sized particle trapped and spinning at tens of Hz in an...

  9. Metrological analysis of a virtual flowmeter-based transducer for cryogenic helium

    The metrological performance of a virtual flowmeter-based transducer for monitoring helium under cryogenic conditions is assessed. At this aim, an uncertainty model of the transducer, mainly based on a valve model, exploiting finite-element approach, and a virtual flowmeter model, based on the Sereg-Schlumberger method, are presented. The models are validated experimentally on a case study for helium monitoring in cryogenic systems at the European Organization for Nuclear Research (CERN). The impact of uncertainty sources on the transducer metrological performance is assessed by a sensitivity analysis, based on statistical experiment design and analysis of variance. In this way, the uncertainty sources most influencing metrological performance of the transducer are singled out over the input range as a whole, at varying operating and setting conditions. This analysis turns out to be important for CERN cryogenics operation because the metrological design of the transducer is validated, and its components and working conditions with critical specifications for future improvements are identified

  10. Metrological analysis of a virtual flowmeter-based transducer for cryogenic helium

    Arpaia, P.; Girone, M.; Liccardo, A.; Pezzetti, M.; Piccinelli, F.

    2015-12-01

    The metrological performance of a virtual flowmeter-based transducer for monitoring helium under cryogenic conditions is assessed. At this aim, an uncertainty model of the transducer, mainly based on a valve model, exploiting finite-element approach, and a virtual flowmeter model, based on the Sereg-Schlumberger method, are presented. The models are validated experimentally on a case study for helium monitoring in cryogenic systems at the European Organization for Nuclear Research (CERN). The impact of uncertainty sources on the transducer metrological performance is assessed by a sensitivity analysis, based on statistical experiment design and analysis of variance. In this way, the uncertainty sources most influencing metrological performance of the transducer are singled out over the input range as a whole, at varying operating and setting conditions. This analysis turns out to be important for CERN cryogenics operation because the metrological design of the transducer is validated, and its components and working conditions with critical specifications for future improvements are identified.

  11. Metrological analysis of a virtual flowmeter-based transducer for cryogenic helium

    Arpaia, P., E-mail: pasquale.arpaia@unina.it [Department of Electrical Engineering and Information Technology, University of Napoli Federico II, Naples (Italy); Technology Department, European Organization for Nuclear Research (CERN), Geneva (Switzerland); Girone, M., E-mail: mario.girone@cern.ch [Technology Department, European Organization for Nuclear Research (CERN), Geneva (Switzerland); Department of Engineering, University of Sannio, Benevento (Italy); Liccardo, A., E-mail: annalisa.liccardo@unina.it [Department of Electrical Engineering and Information Technology, University of Napoli Federico II, Naples (Italy); Pezzetti, M., E-mail: marco.pezzetti@cern.ch [Technology Department, European Organization for Nuclear Research (CERN), Geneva (Switzerland); Piccinelli, F., E-mail: fabio.piccinelli@cern.ch [Department of Mechanical Engineering, University of Brescia, Brescia (Italy)

    2015-12-15

    The metrological performance of a virtual flowmeter-based transducer for monitoring helium under cryogenic conditions is assessed. At this aim, an uncertainty model of the transducer, mainly based on a valve model, exploiting finite-element approach, and a virtual flowmeter model, based on the Sereg-Schlumberger method, are presented. The models are validated experimentally on a case study for helium monitoring in cryogenic systems at the European Organization for Nuclear Research (CERN). The impact of uncertainty sources on the transducer metrological performance is assessed by a sensitivity analysis, based on statistical experiment design and analysis of variance. In this way, the uncertainty sources most influencing metrological performance of the transducer are singled out over the input range as a whole, at varying operating and setting conditions. This analysis turns out to be important for CERN cryogenics operation because the metrological design of the transducer is validated, and its components and working conditions with critical specifications for future improvements are identified.

  12. Doppler cooling and trapping on forbidden transitions

    Binnewies, T.; Wilpers, G.; Sterr, U.; Riehle, F.; Helmcke, J.; Mehlstäubler, T. E.; Rasel, E. M.; Ertmer, W.

    2001-01-01

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of ^40Ca atoms has been cooled and trapped to a temperature as low as 6 \\mu K by operating a magneto-optical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method more than 1...

  13. Gas Dynamical Capillary Flowmeters of Small and Micro Flowrates of Gases

    Stasiuk, Ivan

    2015-01-01

    The possibility of application of glass capillary tubes (CTs) as sensors of small and micro flowrates of gases was justified. The accuracy of a number of CTs flowrate equations was analyzed on the basis of experimental studies of CTs flowrate characteristics. It was shown that CTs can be applied as primary devices of small and micro flowrates of gases without individual calibration. The results of studies on the dynamic properties of gas dynamical capillary flowmeters of small and micro flowr...

  14. Theory of errors in Coriolis flowmeter readings due to compressibility of the fluid being metered

    Kutin, Jože; Hemp, John

    2015-01-01

    The compressibility of fluids in a Coriolis mass flowmeter can cause errors in the meter's measurements of density and mass flow rate. These errors may be better described as errors due to the finite speed of sound in the fluid being metered, or due to the finite wavelength of sound at the operating frequency of the meter. In this paper, they are investigated theoretically and calculated to a first approximation (small degree of compressibility). The investigation is limited to straight beam-...

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

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

  16. Empirical Correlations for Thermal Flowmeters Covering a Wide Range of Thermal-Physical Properties

    Thermal flowmeters can provide direct mass flow measurement of gases and vapors over a wide range of process conditions without the need for density corrections based on pressure and temperature. They are widely used in industrial processes that contain toxic, corrosive, or highly reactive gases. It is often not possible to calibrate the flowmeter on the process gas in which it will be used. In this case a non-hazardous surrogate gas is used for calibration, and a theoretical model used to predict the meters response in the process gas. This can lead to large measurement errors because there are no accurate and straightforward methods for predicting the performance on one kind of gas based on the calibration on another gas because of the complexity of the thermal processes within the flow sensor. This paper describes some of the commonly used models and conversion methods and presents work done at ORNL to develop and experimentally verify better thermal models for predicting flowmeter performance

  17. A coupled finite-element, boundary-integral method for simulating ultrasonic flowmeters.

    Bezdĕk, Michal; Landes, Hermann; Rieder, Alfred; Lerch, Reinhard

    2007-03-01

    Today's most popular technology of ultrasonic flow measurement is based on the transit-time principle. In this paper, a numerical simulation technique applicable to the analysis of transit-time flowmeters is presented. A flowmeter represents a large simulation problem that also requires computation of acoustic fields in moving media. For this purpose, a novel boundary integral method, the Helmholtz integral-ray tracing method (HIRM), is derived and validated. HIRM is applicable to acoustic radiation problems in arbitrary mean flows at low Mach numbers and significantly reduces the memory demands in comparison with the finite-element method (FEM). It relies on an approximate free-space Green's function which makes use of the ray tracing technique. For simulation of practical acoustic devices, a hybrid simulation scheme consisting of FEM and HIRM is proposed. The coupling of FEM and HIRM is facilitated by means of absorbing boundaries in combination with a new, reflection-free, acoustic-source formulation. Using the coupled FEM-HIRM scheme, a full three-dimensional (3-D) simulation of a complete transit-time flowmeter is performed for the first time. The obtained simulation results are in good agreement with measurements both at zero flow and under flow conditions. PMID:17375833

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

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

  19. Influence of speckle effect on doppler velocity measurement

    Zheng, Zheng; Changming, Zhao; Haiyang, Zhang; Suhui, Yang; Dehua, Zhang; Xingyuan, Zheng; Hongzhi, Yang

    2016-06-01

    In a coherent Lidar system, velocity measurement of a target is achieved by measuring Doppler frequency shift between the echo and local oscillator (LO) signals. The measurement accuracy is proportional to the spectrum width of Doppler signal. Actually, the speckle effect caused by the scattering of laser from a target will broaden the Doppler signal's spectrum and bring uncertainty to the velocity measurement. In this paper, a theoretical model is proposed to predict the broadening of Doppler spectrum with respect to different target's surface and motion parameters. The velocity measurement uncertainty caused by the broadening of spectrum is analyzed. Based on the analysis, we design a coherent Lidar system to measure the velocity of the targets with different surface roughness and transverse velocities. The experimental results are in good agreement with theoretical analysis. It is found that the target's surface roughness and transverse velocity can significantly affect the spectrum width of Doppler signal. With the increase of surface roughness and transverse velocity, the measurement accuracy becomes worse. However, the influence of surface roughness becomes weaker when the spot size of laser beam on the target is smaller.

  20. Imaging doppler lidar for wind turbine wake profiling

    Bossert, David J.

    2015-11-19

    An imaging Doppler lidar (IDL) enables the measurement of the velocity distribution of a large volume, in parallel, and at high spatial resolution in the wake of a wind turbine. Because the IDL is non-scanning, it can be orders of magnitude faster than conventional coherent lidar approaches. Scattering can be obtained from naturally occurring aerosol particles. Furthermore, the wind velocity can be measured directly from Doppler shifts of the laser light, so the measurement can be accomplished at large standoff and at wide fields-of-view.

  1. Doppler Beats or Interference Fringes?

    Kelly, Paul S.

    1979-01-01

    Discusses the following: another version of Doppler beats; alternate proof of spin-1 sin-1/2 problems; some mechanisms related to Dirac's strings; Doppler redshift in oblique approach of source and observer; undergraduate experiment on noise thermometry; use of the time evolution operator; resolution of an entropy maximization controversy;…

  2. Incoherent pulse Doppler lidar as the velocimeter system

    2002-01-01

    This note reports a new type of incoherent pulse laser Doppler lidar velocimeter with iodine molecular filter as a frequency discriminator. Its transmitter subsystem applies a Nd:YAG pulse laser which is injected with a single longitudinal-mode diode pumped continuous seeder laser.The field experiment proved that this velocimeter measurement results are consistent with those measured by photoelectric velocimeter. Measurements of eight different velocities show that the standard deviation is 0.56 m/s, the range resolution is 3.75 m.

  3. Adaptive Spectral Doppler Estimation

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-01-01

    In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence....... The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested and...... compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of...

  4. Effect of surface reflectivity on photonic Doppler velocimetry measurement

    While photonic Doppler velocimetry (PDV) is becoming a common diagnostic for tracking velocity in shock physical experiments, its validity on measuring surfaces with different reflectivity is not studied. This paper investigates the effects of surface reflectivity on PDV measurement for tracking back free surface velocity in laser shock processing. Credible measurement results for coarse polished surfaces with low reflectivity are obtained, whereas fine polished surfaces with relatively high reflectivity lead to heterodyne fringes with high frequency and corresponding unreasonably fast velocities. This phenomenon reported in the paper is somewhat inconsistent with the general view that PDV has remarkable robustness to large changes in surface reflectivity. The reason might be ascribed to multiple reflections of light, which cause the generation of multiple Doppler shifts. The mixing of the reference light and those Doppler-shifted lights brings out high frequency heterodyne fringes resulting in high velocity. Low surface reflectivity is better suited for PDV measurements. (paper)

  5. Discussion on the Use of Ultrasonic Flowmeter%浅谈超声波流量计的使用

    程杰; 李福成

    2012-01-01

    In this paper the composition and working principle of ultrasonic flowmeter for the introduction, focuses on the analysis of the ultrasonic flowmeter installation and usage requirement, common failure phenomena and disposal method.%本文对超声波流量计的组成和工作原理作了一定的介绍,着重分析了超声波流量计的安装和使用要求,常见故障的现象和处理方法。

  6. DESIGN, FABRICATION, TESTING AND MECHANICAL ANALYSIS OF BULK-MICROMACHINED FLOWMETERS

    Wang Xiaobao; Qian Jin; Zhang Dacheng

    2004-01-01

    Micromachined piezoresistive flowmeters with four different types of sensing structures have been designed, fabricated and tested. Piezoresistors were defined at the end of the sensors through p-diffusion, and their values were about 3.5 kΩ. Wheatstone bridge was configured with the piezoresistors in order to measure the output response. The output voltage increases with increasing flow rate of air, obeying determined relationships. The testing results show that the sensors that are designed for measuring 10L/M in full operational range have desired sensitivities. The sensor chip is manufactured with bulk-micromachining technologies, requiring a set of seven masks.

  7. A study on improvement of measurement capability for gravimetric flowmeter calibrator

    The calibration of flowmeter is a very important procedure to set up traceability from the national or international standards. The uncertainty of flow measurement defines reliability for measurement results. The uncertainty of gravimetric method combines uncertainties of each independent variable, including mass, time, water density, air density and the density of dead weight. In this study, it has been found that the uncertainties of mass and time measurement in the gravimetric method have dominant influence on the total measurement uncertainty. After improvements of a constant head tank and a diverter, the best measurement capability for K-water's calibration facility has been reached less than 0.1%.

  8. Lasers

    Passeron, Thierry

    2012-01-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be succesfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-aulait macules should not be treated as the relapse...

  9. Dual-Doppler Feasibility Study

    Huddleston, Lisa L.

    2012-01-01

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

  10. Laser spectroscopy

    Demtröder, Wolfgang

    Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., ultrafast lasers (atto- and femto-second lasers) and parametric oscillators, coherent matter waves, Doppler-free Fourier spectroscopy with optical frequency combs, interference spectroscopy, quantum optics, the interferometric detection of gravitational waves and still more applications in chemical analysis, medical diagnostics, and engineering.

  11. Ghost features in Doppler-broadened spectra of rovibrational transitions in trapped HD$^+$ ions

    Patra, Sayan

    2016-01-01

    Doppler broadening plays an important role in laser rovibrational spectroscopy of trapped deuterated molecular hydrogen ions (HD$^+$), even at the millikelvin temperatures achieved through sympathetic cooling by laser-cooled beryllium ions. Recently, Biesheuvel \\textit{et al.} \\cite{Biesheuvel2016} presented a theoretical lineshape model for such transitions which not only considers linestrengths and Doppler broadening, but also the finite sample size and population redistribution by blackbody radiation, which are important in view of the long storage and probe times achievable in ion traps. Here, we employ the rate equation model developed by Biesheuvel \\textit{et al.} to theoretically study the Doppler-broadened hyperfine structure of the $(v,L):(0,3)\\rightarrow(4,2)$ rovibrational transition in HD$^+$ at 1442~nm. We observe prominent yet hitherto unrecognized ghost features in the simulated spectrum, whose positions depend on the Doppler width, transition rates, and saturation levels of the hyperfine compo...

  12. Multipoint photonic doppler velocimetry using optical lens elements

    Frogget, Brent Copely; Romero, Vincent Todd

    2014-04-29

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

  13. 超声波流量计与质量流量计原油计量能耗比较%The Comparison of Energy Consumption of Crude Oil Flow Measurement of Ultrasonic Flowmeter and the Mass Flowmeter

    杨海河

    2015-01-01

    In this paper, the problem in crude oil measurement by using quality flowmeter is analysed combined with a refinery of crude oil flow measurement.And the pressure loss and the energy consumption of mass flowmeter produced in the measuring process are specialy calculated .The working principle of the ultrasonic flowmeter and the advantages of GE measurement level of ultrasonic flowmeter are briefly stated. The two meter measuring energy consumption of crude oil were compared, and provides a new idea for the selection of crude oil metering instrument.%本文结合某炼厂原油进厂流量计量,分析了采用质量流量计实现原油计量存在的问题。对质量流量计在测量过程中产生的压损、能耗进行了具体地计算。简单介绍了超声波流量计的工作原理及GE公司计量级超声波流量计的优点,并将两种流量计原油测量能耗进行了比较,为原油计量仪表的选型提供了新的思路。

  14. Metrological analysis of a virtual flowmeter-based transducer for cryogenic helium.

    Arpaia, P; Girone, M; Liccardo, A; Pezzetti, M; Piccinelli, F

    2015-12-01

    The metrological performance of a virtual flowmeter-based transducer for monitoring helium under cryogenic conditions is assessed. At this aim, an uncertainty model of the transducer, mainly based on a valve model, exploiting finite-element approach, and a virtual flowmeter model, based on the Sereg-Schlumberger method, are presented. The models are validated experimentally on a case study for helium monitoring in cryogenic systems at the European Organization for Nuclear Research (CERN). The impact of uncertainty sources on the transducer metrological performance is assessed by a sensitivity analysis, based on statistical experiment design and analysis of variance. In this way, the uncertainty sources most influencing metrological performance of the transducer are singled out over the input range as a whole, at varying operating and setting conditions. This analysis turns out to be important for CERN cryogenics operation because the metrological design of the transducer is validated, and its components and working conditions with critical specifications for future improvements are identified. PMID:26724060

  15. Experimental evaluation of permanent magnet probe flowmeter measuring high temperature liquid sodium flow in the ITSL

    Highlights: • An Instrument Test Sodium Loop (ITSL) has been built and tested in various conditions at KAERI. • Free fall of liquid sodium was conducted experimentally and numerically. • A Permanent Magnet Probe Flowmeter (PMPF) was experimented in the ITSL. • Excellent linearity of the PMPF was achieved under high temperature condition. - Abstract: The Instrument Test Sodium Loop (ITSL) installed at Korea Atomic Energy Research Institute (KAERI) is a medium-size experimental facility dedicated to obtaining relevant experimental data of liquid sodium flow characteristics under various thermal hydraulic conditions and sodium purification. The ITSL has been utilized to perform thermal flow measurement of the liquid sodium and to calibrate a Permanent Magnet Probe Flowmeter (PMPF). The primary objective of this study is to obtain liquid sodium flow rate given a wide temperature range using the PMPF. Non-stationary method was adopted for the calibration of the probe given the liquid sodium temperature range of 150–415 °C. A relationship between the measured voltage signal and flow rate was obtained successfully. It is observed that the calibration experiments result in excellent linear relationships between measured voltage and volumetric flow rate at various temperature conditions. Also a computational analysis using FlowMaster, is employed to facilitate the calibration process by predicting the liquid sodium flow rate. Finally the effect of the fluid temperature on thermal flow measurements is discussed in light of the obtained experimental data

  16. Experimental evaluation of permanent magnet probe flowmeter measuring high temperature liquid sodium flow in the ITSL

    Jeong, Uiju; Kim, Yun Ho [Nuclear engineering Department, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Jong-Man; Kim, Tae-Joon [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Sung Joong, E-mail: sungjkim@mit.edu [Nuclear engineering Department, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2013-12-15

    Highlights: • An Instrument Test Sodium Loop (ITSL) has been built and tested in various conditions at KAERI. • Free fall of liquid sodium was conducted experimentally and numerically. • A Permanent Magnet Probe Flowmeter (PMPF) was experimented in the ITSL. • Excellent linearity of the PMPF was achieved under high temperature condition. - Abstract: The Instrument Test Sodium Loop (ITSL) installed at Korea Atomic Energy Research Institute (KAERI) is a medium-size experimental facility dedicated to obtaining relevant experimental data of liquid sodium flow characteristics under various thermal hydraulic conditions and sodium purification. The ITSL has been utilized to perform thermal flow measurement of the liquid sodium and to calibrate a Permanent Magnet Probe Flowmeter (PMPF). The primary objective of this study is to obtain liquid sodium flow rate given a wide temperature range using the PMPF. Non-stationary method was adopted for the calibration of the probe given the liquid sodium temperature range of 150–415 °C. A relationship between the measured voltage signal and flow rate was obtained successfully. It is observed that the calibration experiments result in excellent linear relationships between measured voltage and volumetric flow rate at various temperature conditions. Also a computational analysis using FlowMaster, is employed to facilitate the calibration process by predicting the liquid sodium flow rate. Finally the effect of the fluid temperature on thermal flow measurements is discussed in light of the obtained experimental data.

  17. The combined use of heat-pulse flowmeter logging and packer testing for transmissive fracture recognition

    Lo, Hung-Chieh; Chen, Po-Jui; Chou, Po-Yi; Hsu, Shih-Meng

    2014-06-01

    This paper presents an improved borehole prospecting methodology based on a combination of techniques in the hydrogeological characterization of fractured rock aquifers. The approach is demonstrated by on-site tests carried out in the Hoshe Experimental Forest site and the Tailuge National Park, Taiwan. Borehole televiewer logs are used to obtain fracture location and distribution along boreholes. The heat-pulse flow meter log is used to measure vertical velocity flow profiles which can be analyzed to estimate fracture transmissivity and to indicate hydraulic connectivity between fractures. Double-packer hydraulic tests are performed to determine the rock mass transmissivity. The computer program FLASH is used to analyze the data from the flowmeter logs. The FLASH program is confirmed as a useful tool which quantitatively predicts the fracture transmissivity in comparison to the hydraulic properties obtained from packer tests. The location of conductive fractures and their transmissivity is identified, after which the preferential flow paths through the fracture network are precisely delineated from a cross-borehole test. The results provide robust confirmation of the use of combined flowmeter and packer methods in the characterization of fractured-rock aquifers, particularly in reference to the investigation of groundwater resource and contaminant transport dynamics.

  18. Detecting the gas bubbles in a liquid metal coolants by mans of magnetic flowmeters

    Solution of some problems of control and diagnosis of circuits with a liquid-metal coolant (LMC) often requires the detection of gas bubbles penetrating the circulaton loop. The sources of gas intake can be presented by failed fuel elements in reactor core, failed heat-exchange surfaces in sodium-water steam generators in the secondary circuits, gas capture by circulating coolant from gas circuits. Sometimes the gas is especially injected into circulating coolant to study the dynamics of accumulation and extraction of gas bubbles and to solve research problems, related to simulations of emergency situations. The most commonly used methods for gas bubble detection include methods, based on measuring coolant electric conductivity. Method for detecting gas bubbles in LMC, based on revealing the change of its electric conductivity is considered. Magnetic flowmeter is used as a detecting element of these changes. Approximate theory for describing spectral and energy noises in signals of a magnetic flowmeter, controlling the flow rate of LMC with gas bubbles is suggested. New method for signal reading is suggested. Experimental results, illustrating possibility of using the method for measuring the rate of bubble movement and studying the dependence of gas bubble volume on the flow rate of injected gas are presented

  19. Application of a vortex shedding flowmeter to the wide range measurement of high temperature gas flow

    A single flowmeter was required for helium gas measurement in a Gas Cooled Fast Breeder Reactor loss of coolant simulator. Volumetric flow accuracy of +-1.0% of reading was required over the Reynolds Number range 6 x 103 to 1 x 106 at flowing pressures from 0.2 to 9 MPa (29 to 1305 psia) at 3500C (6600F) flowing temperature. Because of its inherent accuracy and rangeability, a vortex shedding flowmeter was selected and specially modified to provide for a remoted thermal sensor. Experiments were conducted to determine the relationship between signal attenuation and sensor remoting geometry, as well as the relationship between gas flow parameters and remoted thermal sensor signal for both compressed air and helium gas. Based upon the results of these experiments, the sensor remoting geometry was optimized for this application. The resultant volumetric flow rangeability was 155:1. The associated temperature increase at the sensor position was 90C above ambient (250F) at a flowing temperature of 3500C. The volumetric flow accuracy was measured over the entire 155:1 flow range at parametric values of flowing density. A volumetric flow accuracy of +- % of reading was demonstrated

  20. Application of a vortex shedding flowmeter to the wide range measurement of high temperature gas flow

    Baker, S.P.; Ennis, R.M. Jr.; Herndon, P.G.

    1981-01-01

    A single flowmeter was required for helium gas measurement in a Gas Cooled Fast Breeder Reactor loss of coolant simulator. Volumetric flow accuracy of +-1.0% of reading was required over the Reynolds Number range 6 x 10/sup 3/ to 1 x 10/sup 6/ at flowing pressures from 0.2 to 9 MPa (29 to 1305 psia) at 350/sup 0/C (660/sup 0/F) flowing temperature. Because of its inherent accuracy and rangeability, a vortex shedding flowmeter was selected and specially modified to provide for a remoted thermal sensor. Experiments were conducted to determine the relationship between signal attenuation and sensor remoting geometry, as well as the relationship between gas flow parameters and remoted thermal sensor signal for both compressed air and helium gas. Based upon the results of these experiments, the sensor remoting geometry was optimized for this application. The resultant volumetric flow rangeability was 155:1. The associated temperature increase at the sensor position was 9/sup 0/C above ambient (25/sup 0/F) at a flowing temperature of 350/sup 0/C. The volumetric flow accuracy was measured over the entire 155:1 flow range at parametric values of flowing density. A volumetric flow accuracy of +- % of reading was demonstrated.

  1. Observing Molecular Spinning via the Rotational Doppler Effect

    Korech, Omer; Steinitz, Uri; Gordon, Robert J.; Averbukh, Ilya. Sh.; Prior, Yehiam

    2013-01-01

    When circularly polarized light is scattered from a rotating target, a rotational Doppler shift (RDS) emerges from an exchange of angular momentum between the spinning object and the electromagnetic field. Here, we used coherently spinning molecules to generate a shift of the frequency of a circularly polarized probe propagating through a gaseous sample. We used a linearly polarized laser pulse to align the molecules, followed by a second delayed pulse polarized at 45{\\deg} to achieve unidire...

  2. Line shapes in sub-Doppler DAVLL in the 87Rb-D2 line

    Choi, Gyeong-Won; Noh, Heung-Ryoul

    2016-05-01

    We present a theoretical and experimental study of the sub-Doppler dichroic atomic vapor laser lock (DAVLL) for the D2 transition line of 87Rb atoms. The experimental results of the sub-Doppler DAVLL spectra are compared with calculated results using both accurate density matrix equations and approximate rate equations. We find good agreement between the experimental and calculated results. In particular, the coherence effect must be included in the signal for the cycling transition line.

  3. Influences of Doppler effect on spontaneously generated coherence in a Rb atom

    Song, Zhuo; Zheng, Y.

    2015-11-01

    We study the influences of Doppler effect on spontaneously generated coherence in a Rb atom driven by a probe field and two control fields. We show that the propagating directions of the lasers and the wave-vector mismatch have influence on the absorption properties of the atom. By employing the Doppler effect and spontaneous generated coherence, the ultra-narrow lines in probe absorption profile near two-photon resonant position can be obtained.

  4. Influences of Doppler effect on spontaneously generated coherence in a Rb atom

    We study the influences of Doppler effect on spontaneously generated coherence in a Rb atom driven by a probe field and two control fields. We show that the propagating directions of the lasers and the wave-vector mismatch have influence on the absorption properties of the atom. By employing the Doppler effect and spontaneous generated coherence, the ultra-narrow lines in probe absorption profile near two-photon resonant position can be obtained. (authors)

  5. Coherence-gated Doppler: a fiber sensor for precise localization of blood flow

    Liang, Chia-Pin; Wu, Yalun; Schmitt, Joe; Bigeleisen, Paul E.; Slavin, Justin; Jafri, M. Samir; Tang, Cha-Min; Chen, Yu

    2013-01-01

    Miniature optical sensors that can detect blood vessels in front of advancing instruments will significantly benefit many interventional procedures. Towards this end, we developed a thin and flexible coherence-gated Doppler (CGD) fiber probe (O.D. = 0.125 mm) that can be integrated with minimally-invasive tools to provide real-time audio feedback of blood flow at precise locations in front of the probe. Coherence-gated Doppler (CGD) is a hybrid technology with features of laser Doppler flowme...

  6. Doppler cooling and trapping on forbidden transitions

    Binnewies, T; Sterr, U; Riehle, F; Helmcke, J; Mehlstäubler, T E; Rasel, E M; Ertmer, W

    2001-01-01

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of ^40Ca atoms has been cooled and trapped to a temperature as low as 6 \\mu K by operating a magneto-optical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method more than 10% of pre-cooled atoms from a standard magneto-optical trap have been transferred to the ultracold trap. Monte-Carlo simulations of the cooling process are in good agreement with the experiments.

  7. Doppler cooling and trapping on forbidden transitions.

    Binnewies, T; Wilpers, G; Sterr, U; Riehle, F; Helmcke, J; Mehlstäubler, T E; Rasel, E M; Ertmer, W

    2001-09-17

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of (40)Ca atoms has been cooled and trapped to a temperature as low as 6 microK by operating a magnetooptical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method, more than 10% of precooled atoms from a standard magnetooptical trap have been transferred to the ultracold trap. Monte Carlo simulations of the cooling process are in good agreement with the experiments. PMID:11580503

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

    Rhodes, Mark

    2013-12-17

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

  9. Planetary Doppler Imaging

    Murphy, N.; Jefferies, S.; Hart, M.; Hubbard, W. B.; Showman, A. P.; Hernandez, G.; Rudd, L.

    2014-12-01

    Determining the internal structure of the solar system's gas and ice giant planets is key to understanding their formation and evolution (Hubbard et al., 1999, 2002, Guillot 2005), and in turn the formation and evolution of the solar system. While internal structure can be constrained theoretically, measurements of internal density distributions are needed to uncover the details of the deep interior where significant ambiguities exist. To date the interiors of giant planets have been probed by measuring gravitational moments using spacecraft passing close to, or in orbit around the planet. Gravity measurements are effective in determining structure in the outer envelope of a planet, and also probing dynamics (e.g. the Cassini and Juno missions), but are less effective in probing deep structure or the presence of discrete boundaries. A promising technique for overcoming this limitation is planetary seismology (analogous to helioseismology in the solar case), postulated by Vorontsov, 1976. Using trapped pressure waves to probe giant planet interiors allows insight into the density and temperature distribution (via the sound speed) down to the planetary core, and is also sensitive to sharp boundaries, for example at the molecular to metallic hydrogen transition or at the core-envelope interface. Detecting such boundaries is not only important in understanding the overall structure of the planet, but also has implications for our understanding of the basic properties of matter at extreme pressures. Recent Doppler measurements of Jupiter by Gaulme et al (2011) claimed a promising detection of trapped oscillations, while Hedman and Nicholson (2013) have shown that trapped waves in Saturn cause detectable perturbations in Saturn's C ring. Both these papers have fueled interest in using seismology as a tool for studying the solar system's giant planets. To fully exploit planetary seismology as a tool for understanding giant planet structure, measurements need to be made

  10. Mathematical Evaluation of Steady, Laminar Flow by the Use of Continuous-Wave (cw) Doppler and Pitot Tube System.

    Sharif, Malek Mansoor

    Investigation, as to the usefulness of spectral analysis of the acoustical signal from the Doppler ultrasonic flowmeter, is being conducted. The hypothesis was that both hematocrit ((')H) and pressure head (H) influence the amplitude of the spectrum (A). Experiments were designed to: (a) evaluate their roles on amplitude; (b) derive the associated functional relationship. Preliminary experiments revealed that: (a) the accuracy of our Doppler flowmeter was satisfactory; (b) the relative weight of (')H on flow velocity was twice that of H. A pitot tube system whose bent tube component was capable of radial movement was developed to measure the instantaneous blood velocity. The bent tube was moved across the lumen of the vessel in steps of 0.1 mm, and particle velocity was measured at each sampling point. The distribution of velocity was parabolic and the agreement between experimental data and the second degree polynomial fit was good ((xi) = .94). An array of small bent tubes, each placed successively deeper within the lumen of the rubber tubing and connected to a small syringe, was constructed to measure the particle profile. The profile was parabolic and (')H, as a function of radius, was expressible in terms of a second degree polynomial. To determine the dependency of ultrasonic energy backscattering on hematocrit, Doppler signals were recorded, digitized, and frequency resolved via the fast Fourier transform for hematocrits ranging from 4.5% to 46.5%. The amplitude corresponding to each given hematocrit was calculated by evaluating the area under the curve fitted to the transformed data. A((')H) was found to be a linear function of hematocrit. A generalized Doppler amplitude function A(H,(')H) was also derived. It was hypothesized that blood viscosity ((mu)) is an exponential function of hematocrit, that is, (mu) = A exp (B(.)(')H). Experimental results using a Falling ball type viscosimeter supported the theory with a high correlation between the data and the

  11. The Effect of Acoustic Disturbances on the Operation of the Space Shuttle Main Engine Fuel Flowmeter

    Marcu, Bogdan; Szabo, Roland; Dorney, Dan; Zoladz, Tom

    2007-01-01

    The Space Shuttle Main Engine (SSME) uses a turbine fuel flowmeter (FFM) in its Low Pressure Fuel Duct (LPFD) to measure liquid hydrogen flowrates during engine operation. The flowmeter is required to provide accurate and robust measurements of flow rates ranging from 10000 to 18000 GPM in an environment contaminated by duct vibration and duct internal acoustic disturbances. Errors exceeding 0.5% can have a significant impact on engine operation and mission completion. The accuracy of each sensor is monitored during hot-fire engine tests on the ground. Flow meters which do not meet requirements are not flown. Among other parameters, the device is screened for a specific behavior in which a small shift in the flow rate reading is registered during a period in which the actual fuel flow as measured by a facility meter does not change. Such behavior has been observed over the years for specific builds of the FFM and must be avoided or limited in magnitude in flight. Various analyses of the recorded data have been made prior to this report in an effort to understand the cause of the phenomenon; however, no conclusive cause for the shift in the instrument behavior has been found. The present report proposes an explanation of the phenomenon based on interactions between acoustic pressure disturbances in the duct and the wakes produced by the FFM flow straightener. Physical insight into the effects of acoustic plane wave disturbances was obtained using a simple analytical model. Based on that model, a series of three-dimensional unsteady viscous flow computational fluid dynamics (CFD) simulations were performed using the MSFC PHANTOM turbomachinery code. The code was customized to allow the FFM rotor speed to change at every time step according to the instantaneous fluid forces on the rotor, that, in turn, are affected by acoustic plane pressure waves propagating through the device. The results of the simulations show the variation in the rotation rate of the flowmeter

  12. Inverse Doppler Effects in Flute

    Zhao, Xiao P; Liu, Song; Shen, Fang L; Li, Lin L; Luo, Chun R

    2015-01-01

    Here we report the observation of the inverse Doppler effects in a flute. It is experimentally verified that, when there is a relative movement between the source and the observer, the inverse Doppler effect could be detected for all seven pitches of a musical scale produced by a flute. Higher tone is associated with a greater shift in frequency. The effect of the inverse frequency shift may provide new insights into why the flute, with its euphonious tone, has been popular for thousands of years in Asia and Europe.

  13. Doppler Ultrasound Doppler and their applications in maternal medicine

    In this paper the technical aspects and physical principles of Doppler ultrasound are discussed, as well as the analysis that can be made from the quantitative and qualitative data. Finally, its utility in perinatal medicine is reviewed with emphasis in the clinical implications

  14. Comparisons between PW Doppler system and enhanced FM Doppler system

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

    system exploits the direct relationship between arrival time of the received signal and range from the transducer. In the FM Doppler systems, a similar relationship exists in the spectral domain of the demodulated received signals, so that range is represented by frequency. Thus, a shift in location of...

  15. Doppler tomography in fusion plasmas and astrophysics

    Salewski, Mirko; Heidbrink, Bill; Jacobsen, Asger Schou; Korsholm, Soren Bang; Leipold, Frank; Madsen, Jens; Moseev, Dmitry; Nielsen, Stefan Kragh; Rasmussen, Jesper; Stagner, Luke; Steeghs, Danny; Stejner, Morten; Tardini, Giovani; Weiland, Markus

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion D-alpha (FIDA) spectroscopy measurements in magnetically confined plasma, the D-alpha-photons are likewise Doppler-shifted ultimately due to gyration of the fast ions. In either case, spectra of Doppler-shifted line emission are sensitive to the velocity distribution of the emitters. Astrophysical Doppler tomography has lead to images of accretion discs of binaries revealing bright spots, spiral structures, and flow patterns. Fusion plasma Doppler tomography has lead to an image of the fast-ion velocity distribution function in the tokamak ASDEX Upgrade. This image matched numerical simulations very well. Here we discuss achievements of the Doppler tomography approach, its promise and limits, analogies and differences in astrophysical and fusion plasma Doppler tomography, and what ...

  16. 温度、压力对超声波流量计影响浅析%Temperature and pressure effect on ultrasonic flowmeter is analysed

    郝新刚; 王志强; 苗键

    2015-01-01

    Through the ultrasonic flowmeter in use process with the changing of temperature, pressure, flow fluctuations, the analysis of the effect of temperature and pressure on the ultrasonic flowmeter.%通过超声波流量计在使用过程中随着温度、压力的的不断变化而出现流量的波动,分析温度、压力对超声波流量计的影响.

  17. Applications of Doppler optical coherence tomography

    Xu, Zhiqiang

    A major development in biomedical imaging in the last decade has been optical coherence tomography (OCT). This technique enables microscale resolution, depth resolved imaging of the detailed morphology of transparent and nontransparent biological tissue in a noncontact and quasi-noninvasive way. In the first part of this dissertation, we will describe the development and the performance of our home-made OCT systems working with different wavelength regions based on free-space and optical fiber Michelson interferometers. The second part will focus on Doppler OCT (DOCT), an important extension of OCT, which enables the simultaneous evaluation of the structural information and of the fluid flow distribution at a localized position beneath the sample surface. Much effort has been spent during the past few years in our laboratory aimed at providing more accurate velocity measurements with an extended dynamic range. We also applied our technique in different research areas such as microfluidics and hemodynamics. Investigations on the optical properties of the biological tissues (such as absorption and scattering) corresponding to different center wavelengths, have been performed in our laboratory. We used a 10 femtosecond Ti:sapphire laser centered at about 810 nm associated with a free-space Michelson interferometer. The infrared sources were centered at about 1310 and 1560 nm with all-fiber interferometers. Comparative studies using three different sources for several in vitro biological tissues based on a graphical method illustrated how the optical properties affect the quality of the OCT images in terms of the penetration depth and backscattering intensity. We have shown the advantage of working with 810-nm emission wavelength for good backscattering amplitude and contrast, while sources emitting at 1570 nm give good penetration depth. The 1330-nm sources provide a good compromise between the two. Therefore, the choice of the source will ultimately determine the

  18. Improved plant economics through accurate feedwater flow measurement with the crossflow ultrasonic flowmeter

    The crossflow ultrasonic flowmeter (UFM) improves nuclear power plant performance through more accurate and reliable feedwater flow measurement. Reactor power levels are typically monitored via secondary-side calorimetric calculations that depend on the accurate measurement of feedwater flow . The feedwater flow is measured with calibrated venturis in most plants. These are subject to chemical fouling and other mechanical problems. If the loss in accuracy of the feedwater flow measurement overstates the actual flow rate, the result is a direct loss in megawatts generated by the plant. This paper describes a new, innovative ultrasonic technique to improve the accuracy, stability and repeatability of ultrasonic flow measurements. By employing this advanced technology to provide a continuous correction to the venturi-measured feed water flow rate, plants have reported the recovery of between 5 and 25 MWe. This technology has been implemented in a new flowmeter called CROSSFLOW. The CROSSFLOW meter utilizes a mathematical process called cross-correlation to process the ultrasonic signal, which is modulated by the flow eddys to determine the velocity of the feedwater. It replaces the older, less accurate transit-time methodology. Comparisons with weigh tank test, calibrated plant instrumentation, and chemical tracer tests have demonstrated a repeatable accuracy of 0.21% or better with this advanced cross-correlation technology. The paper discusses the history of the cross-correlation technique and its theoretical basis, illustrates how this technique addresses the measurement sensitivities for various parameters, demonstrates the calculation of the accuracy of the meter, and discusses the recently completed NRC review of the CROSSFLOW System and methodology. The paper also discusses recent precision flow measurement applications being performed with CROSSFLOW at nuclear plants worldwide. Among these applications are the measurement of Reactor Coolant System flow and the

  19. Anomalous Doppler effects in bulk phononic crystal

    Doppler effects in simple cubic phononic crystal are studied theoretically and numerically. In addition to observing Doppler shifts from a moving source's frequencies inside the gap, we find that Doppler shifts can be multi-order, anisotropic, and the dominant order of shift depends on the band index that the source's frequency is in.

  20. Three-dimensional power doppler imaging

    Three-dimensional (3-D) ultrasonographic imaging techniques have recently shown rapid development and their clinical application has begun to attract considerable attention. Power Doppler sonography is known to be more sensitive than color Doppler for detecting blood flow, and there is also less noise and clutter. This paper describes the basic principles and initial clinical experience of 3-D power Doppler sonography