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Sample records for acoustic doppler velocimeter

  1. Temperature, conductivity, pressure, oxygen concentration, beam attenuation, Chlorophyll-a fluorescence, current speed and direction, and particle size distribution collected from moored platform using CTD, ADCP, acoustic Doppler velocimeter, and benthic optical sensors in Monterey Bay from 2011-05-03 to 2012-10-29 (NODC Accession 0123606)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Observational oceanographic data obtained by an autonomous moored CTD profiler, thermistor mooring, acoustic Doppler current profiler, acoustic Doppler velocimeter,...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-01

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

  3. Widefield laser doppler velocimeter: development and theory.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Coherent Detection in Laser Doppler Velocimeters

    DEFF Research Database (Denmark)

    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 the evaluation of a visual comprehensive interference pattern (Moiré pattern), which furthermore reveals some important features of the optical set-up....

  5. Incoherent pulse Doppler lidar as the velocimeter system

    Institute of Scientific and Technical Information of China (English)

    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.

  6. Effect of speckle pattern on laser Doppler velocimeters

    Institute of Scientific and Technical Information of China (English)

    Liang Lü(吕亮); Huaqiao Gui(桂华侨); Tianpeng Zhao(赵天鹏); Jun Xu(徐军); Deyong He(何德勇); Anting Wang(王安廷); Feng Li(李锋); Hai Ming(明海); Jianping Xie(谢建平)

    2004-01-01

    The effect of speckle pattern on laser Doppler velocimeters is studied theoretically and experimentally. We have found that dynamic speckle patterns can cause error in velocity measurement. Increasing sampling time and using proper signal processing circuits can eliminate this bad effect caused by speckle pattern.The accuracy of velocity measurement is better than 2.1% in a wide velocity range(4.66-468.86 mm/s)when speckle effects are taken into account.

  7. Development of the doppler electron velocimeter: theory.

    Energy Technology Data Exchange (ETDEWEB)

    Reu, Phillip L.

    2007-03-01

    Measurement of dynamic events at the nano-scale is currently impossible. This paper presents the theoretical underpinnings of a method for making these measurements using electron microscopes. Building on the work of Moellenstedt and Lichte who demonstrated Doppler shifting of an electron beam with a moving electron mirror, further work is proposed to perfect and utilize this concept in dynamic measurements. Specifically, using the concept of ''fringe-counting'' with the current principles of transmission electron holography, an extension of these methods to dynamic measurements is proposed. A presentation of the theory of Doppler electron wave shifting is given, starting from the development of the de Broglie wave, up through the equations describing interference effects and Doppler shifting in electron waves. A mathematical demonstration that Doppler shifting is identical to the conceptually easier to understand idea of counting moving fringes is given by analogy to optical interferometry. Finally, potential developmental experiments and uses of a Doppler electron microscope are discussed.

  8. Self-mixing dual-frequency laser Doppler velocimeter.

    Science.gov (United States)

    Cheng, Chih-Hao; Lin, Lyu-Chih; Lin, Fan-Yi

    2014-02-10

    A self-mixing (SM) dual-frequency (DF) laser Doppler velocimeter (LDV) (SM DF-LDV) is proposed and studied, which integrates the advantages of both the SM-LDV and the DF-LDV. An optically injected semiconductor laser operated in a dual-frequency period-one (P1) dynamical state is used as the light source. By probing the target with the light-carried microwave generated from the beat of the two optical frequency components, the spectral broadening in the Doppler signal due to the speckle noise can be significantly reduced. Together with an SM configuration, the SM DF-LDV has the advantages of direction discriminability, self-alignment, high sensitivity, and compact setup. In this study, speckle noise reduction and direction discriminability with an SM DF-LDV are demonstrated. The signal-to-noise ratios (SNRs) at different feedback powers are investigated. Benefiting from the high sensitivity of the SM configuration, an SNR of 23 dB is achieved without employing an avalanched photodetector or photomultiplier tube. The velocity resolution and the SNR under different speckle noise conditions are studied. Average velocity resolution of 0.42 mm/s and SNR of 22.1 dB are achieved when a piece of paper is rotating at a transverse velocity of 5 m/s. Compared with a conventional single-frequency LDV (SF-LDV), the SM DF-LDV shows improvements of 20-fold in the velocity resolution and 8 dB in the SNR.

  9. GLASS-FIBER SELF-MIXING DIODE-LASER DOPPLER-VELOCIMETER

    NARCIS (Netherlands)

    KOELINK, MH; SLOT, M; DEMUL, FFM; GREVE, J; GRAAFF, R; DASSEL, ACM; AARNOUDSE, JG

    1992-01-01

    A novel diode-laser Doppler velocimeter based on self-mixing feedback of Doppler-shifted light in the laser through a single glass fibre is described. The instrument can be applied, for example, to the invasive measurement of blood velocities in blood vessels, and of other industrial fluids and soli

  10. Fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser

    Science.gov (United States)

    Kuang, Zeyuang; Cheng, Linghao; Liang, Yizhi; Liang, Hao; Guan, Bai-Ou

    2015-07-01

    A fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser is demonstrated. The fiber grating laser produces two orthogonally polarized laser outputs with their frequency difference proportional to the intra-cavity birefringence. When the laser outputs are reflected from a moving targets, the laser frequencies will be shifted due to the Doppler effect. It shows that the frequency difference between the beat note of the laser outputs and the beat note of the reflected lasers is proportional to the velocity. The proposed fiber-optic Doppler velocimeter shows a high sensitivity of 0.64 MHz/m/s and is capable of measurement of wide range of velocity.

  11. All-Fiber Configuration Laser Self-Mixing Doppler Velocimeter Based on Distributed Feedback Fiber Laser.

    Science.gov (United States)

    Wu, Shuang; Wang, Dehui; Xiang, Rong; Zhou, Junfeng; Ma, Yangcheng; Gui, Huaqiao; Liu, Jianguo; Wang, Huanqin; Lu, Liang; Yu, Benli

    2016-07-27

    In this paper, a novel velocimeter based on laser self-mixing Doppler technology has been developed for speed measurement. The laser employed in our experiment is a distributed feedback (DFB) fiber laser, which is an all-fiber structure using only one Fiber Bragg Grating to realize optical feedback and wavelength selection. Self-mixing interference for optical velocity sensing is experimentally investigated in this novel system, and the experimental results show that the Doppler frequency is linearly proportional to the velocity of a moving target, which agrees with the theoretical analysis commendably. In our experimental system, the velocity measurement can be achieved in the range of 3.58 mm/s-2216 mm/s with a relative error under one percent, demonstrating that our novel all-fiber configuration velocimeter can implement wide-range velocity measurements with high accuracy.

  12. Development and Testing of the Virginia Tech Doppler Global Velocimeter (DGV)

    OpenAIRE

    Jones, Troy Bland

    2001-01-01

    A new laser based flow interrogation system, capable of simultaneous measurement of planar three-component velocity data, was constructed and tested. The Virginia Tech Doppler Global Velocimeter (DGV) system was designed for use in the Virginia Tech Stability Wind Tunnel as a tool for investigating complex three-dimensional separated flow regions. The systems was designed for robustness, ease of use, and for acquisition of low uncertainty velocity data. A series of tests in the Stability Tunn...

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

    Science.gov (United States)

    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.

  14. Monostatic coaxial 1.5 μm laser Doppler velocimeter using a scanning Fabry-Perot interferometer

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Pedersen, Christian

    2013-01-01

    We present a laser Doppler velocimeter (LDV) in monostatic coaxial arrangement consisting of off-the-shelf telecom-grade components: a single frequency laser (wavelength λ = 1.5 μm) and a high-finesse scanning Fabry-Perot interferometer (sFPI). In contrast to previous 1.5 μm LDV systems based...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

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

    Science.gov (United States)

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

    2012-08-27

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

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

    Science.gov (United States)

    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

  18. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    Science.gov (United States)

    Zhai, S. L.; Zhao, X. P.; Liu, S.; Shen, F. L.; Li, L. L.; Luo, C. R.

    2016-08-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with ‘flute-like’ acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  19. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-08-31

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  20. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-01-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe. PMID:27578317

  1. Embedded Fiber Optic Probes to Measure Detonation Velocities Using the Photonic Doppler Velocimeter

    Energy Technology Data Exchange (ETDEWEB)

    Hare, D E; Holtkamp, D B; Strand, O T

    2010-03-02

    Detonation velocities for high explosives can be in the 7 to 8 km/s range. Previous work has shown that these velocities may be measured by inserting an optical fiber probe into the explosive assembly and recording the velocity time history using a Fabry-Perot velocimeter. The measured velocity using this method, however, is the actual velocity multiplied times the refractive index of the fiber core, which is on the order of 1.5. This means that the velocimeter diagnostic must be capable of measuring velocities as high as 12 km/s. Until recently, a velocity of 12 km/s was beyond the maximum velocity limit of a homodyne-based velocimeter. The limiting component in a homodyne system is usually the digitizer. Recently, however, digitizers have come on the market with 20 GHz bandwidth and 50 GS/s sample rate. Such a digitizer coupled with high bandwidth detectors now have the total bandwidth required to make velocity measurements in the 12 km/s range. This paper describes measurements made of detonation velocities using a high bandwidth homodyne system.

  2. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    Science.gov (United States)

    Zhai, S. L.; Zhao, X. P.; Liu, S.; Shen, F. L.; Li, L. L.; Luo, C. R.

    2016-01-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with ‘flute-like’ acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe. PMID:27578317

  3. Speckle noise reduction of a dual-frequency laser Doppler velocimeter based on an optically injected semiconductor laser

    Science.gov (United States)

    Cheng, Chih-Hao; Lee, Jia-Wei; Lin, Tze-Wei; Lin, Fan-Yi

    2012-02-01

    We develop and investigate a dual-frequency Laser Doppler Velocimeter (DF-LDV) based on an optically injected semiconductor laser. By operating the laser in a period-one oscillation (P1) state, the laser can emit light with two coherent frequency components separated by about 11.25 GHz. Through optical heterodyning, the velocity of the target can be determined from the Doppler shift of the beat signal of the dual-frequency light. While the DF-LDV has the same advantages of good directionality and high intensity as in the conventional singlefrequency LDV (SF-LDV), having an effective wavelength in the range of microwave in the beat signal greatly reduces the speckle noise caused by the random phase modulation from the rough surface of the moving target. To demonstrate the speckle noise reduction, the Doppler shifted signals from a moving target covered by the plain paper are measured both from the SF-LDV and the DF-LDV. The target is rotated to provide a transverse velocity, where the speckle noise increases as the transverse velocity increases. The bandwidth of the Doppler signal obtained from the SF-LDV is increased from 4.7 kHz to 9.4 kHz as the transverse velocity increases from 0 m/s to 5 m/s. In contrast, the bandwidth obtained from the DF-LDV maintains at 0.09 Hz with or without the rotation limited by the linewidth of the P1 state used. By phase-locking the laser with a RF current modulation, the linewidth of the P1 state can be much reduced to further improve the velocity resolution and extend the detection range.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  6. Characterizing Ocean Turbulence from Argo, Acoustic Doppler, and Simulation Data

    Science.gov (United States)

    McCaffrey, Katherine

    Turbulence is inherently chaotic and unsteady, so observing it and modeling it are no easy tasks. The ocean's sheer size makes it even more difficult to observe, and its unpredictable and ever-changing forcings introduce additional complexities. Turbulence in the oceans ranges from basin scale to the scale of the molecular viscosity. The method of energy transfer between scales is, however, an area of active research, so observations of the ocean at all scales are crucial to understanding the basic dynamics of its motions. In this collection of work, I use a variety of datasets to characterize a wide range of scales of turbulence, including observations from multiple instruments and from models with different governing equations. I analyzed the largest scales of the turbulent range using the global salinity data of the Argo profiling float network. Taking advantage of the scattered and discontinuous nature of this dataset, the second-order structure function was calculated down to 2000m depth, and shown to be useful for predicting spectral slopes. Results showed structure function slopes of 2/3 at small scales, and 0 at large scales, which corresponds with spectral slopes of -5/3 at small scales, and -1 at large scales. Using acoustic Doppler velocity measurements, I characterized the meter- to kilometer-scale turbulence at a potential tidal energy site in the Puget Sound, WA. Acoustic Doppler current profiler (ADCP) and acoustic Doppler velocimeter (ADV) observations provided the data for an analysis that includes coherence, anisotropy, and intermittency. In order to more simply describe these features, a parameterization was done with four turbulence metrics, and the anisotropy magnitude, introduced here, was shown to most closely capture the coherent events. Then, using both the NREL TurbSim stochastic turbulence generator and the NCAR large-eddy simulation (LES) model, I calculated turbulence statistics to validate the accuracy of these methods in reproducing

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sellar, Brian [Univ. of Edinburgh, Scotland (United Kingdom); Harding, Samuel F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Richmond, Marshall C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-16

    An array of convergent acoustic Doppler velocimeters has been developed and tested for the high resolution measurement of three-dimensional tidal flow velocities in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use diverging acoustic beams emanating from a single instrument. This is achieved using converging acoustic beams with a sample volume at the focal point of 0.03 m3. The array is also able to simultaneously measure three-dimensional velocity components in a profile throughout the water column, and as such is referred to herein as a converging-beam acoustic Doppler profiler (CADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational Alstom 1MW DeepGen-IV Tidal Turbine. This proof-of-concept paper outlines system configuration and comparison to measurements provided by co-installed reference instrumentation. Comparison of CADP to standard ADP velocity measurements reveals a mean difference of 8 mm/s, standard deviation of 18 mm/s, and order-of-magnitude reduction in realizable length-scale. CADP focal point measurements compared to a proximal single-beam reference show peak cross-correlation coefficient of 0.96 over 4.0 s averaging period and a 47% reduction in Doppler noise. The dual functionality of the CADP as a profiling instrument with a high resolution focal point make this configuration a unique and valuable advancement in underwater velocimetry enabling improved turbulence, resource and structural loading quantification and validation of numerical simulations. Alternative modes of operation have been implemented including noise-reducing bi-static sampling. Since waves are simultaneously measured it is expected that derivatives of this system will be a powerful tool in wave-current interaction studies.

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

    DEFF Research Database (Denmark)

    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....

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

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

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

  11. Calculating "g" from Acoustic Doppler Data

    Science.gov (United States)

    Torres, Sebastian; Gonzalez-Espada, Wilson J.

    2006-01-01

    Traditionally, the Doppler effect for sound is introduced in high school and college physics courses. Students calculate the perceived frequency for several scenarios relating a stationary or moving observer and a stationary or moving sound source. These calculations assume a constant velocity of the observer and/or source. Although seldom…

  12. Doppler compensated underwater acoustic communication system

    Science.gov (United States)

    Raj, Anand; George, Binu; Supiya, M. H.; Kurian, James; Pillai, P. R. Saseendran

    2001-05-01

    Spread spectrum methods are used in communication systems to provide a low probability of intercept in hostile environments and multiple access capability in systems shared by many users as well as to provide high processing gain in channels where the transmitted signal is distorted by multipath effects. Such systems serve to be an effective tool for underwater telemetry environments, where multipath propagation effect and Doppler spreading is seen to be more predominant. This paper describes the implementation of a Doppler compensated underwater telemetry system based on CDMA technique. The system consists of multiple CDMA transmitters and a phase locked loop based carrier recoverable CDMA receiver. The effects of the Doppler shift can be compensated by the carrier recovery subsystem in the demodulator, based on PLL technique, which extracts the carrier frequency/phase and simultaneously demodulates the signal. The decision device in the receiver consists of a PN sequence generator as well as a bank of correlators, which are used to determine the data transmitted. The system simulation has been implemented in MATLAB. The advantage of this system is that multiple transmitting stations can transmit simultaneously to a central receiver, thereby increasing the system throughput.

  13. In situ estimation of erosion and deposition thresholds by Acoustic Doppler Velocimeter (ADV)

    DEFF Research Database (Denmark)

    Andersen, T.J.; Fredsøe, Jørgen; Pejrup, M.

    2007-01-01

    to characterize sediment erodibility is that measurements can be carried out for long periods, which makes it possible to examine the temporal variation of erosion threshold, erosion rate and sedimentation. The maximum bed shear stresses, which was observed during a strong storm in January 2005, was only 0.7 N m......(-2) which is three to four times lower than the highest thresholds measured by EROMES experiments On sediment with biofilms during previous studies. This shows that such strong biofilms at this site will not get eroded unless degraded or physically disrupted by some other mechanism. A prerequisite...... for the determination of any of the erodibility and sedimentation parameters is that the actual bed level changes at the measuring site are known in detail. This information is obtained automatically by the ADVs used in the present study. Accurate estimates of the bed shear stress under waves in very shallow water...

  14. Vector velocimeter

    DEFF Research Database (Denmark)

    2012-01-01

    for generation of a reference beam, a detector system comprising a first detector arrangement arranged in such a way that the signal beam and the reference beam are incident upon the first detector arrangement with the reference beam propagating at an angle relative to a signal beam, and wherein the first......The present invention relates to a compact, reliable and low-cost vector velocimeter for example for determining velocities of particles suspended in a gas or fluid flow, or for determining velocity, displacement, rotation, or vibration of a solid surface, the vector velocimeter comprising a laser...... assembly for emission of a measurement beam for illumination of an object in a measurement volume with coherent light whereby a signal beam emanating from the object in the measurement volume is formed in response to illumination of the object by the measurement beam, a reference beam generator...

  15. HF Doppler observations of acoustic waves excited by the earthquake

    Science.gov (United States)

    Ichinose, T.; Takagi, K.; Tanaka, T.; Okuzawa, T.; Shibata, T.; Sato, Y.; Nagasawa, C.; Ogawa, T.

    1985-01-01

    Ionospheric disturbances caused by the earthquake of a relatively small and large epicentral distance have been detected by a network of HF-Doppler sounders in central Japan and Kyoto station, respectively. The HF-Doppler data of a small epicentral distance, together with the seismic data, have been used to formulate a mechanism whereby ionospheric disturbances are produced by the Urakawa-Oki earthquake in Japan. Comparison of the dynamic spectra of these data has revealed experimentally that the atmosphere acts as a low-pass filter for upward-propagating acoustic waves. By surveying the earthquakes for which the magnitude M is larger than 6.0, researchers found the ionospheric effect in 16 cases of 82 seismic events. As almost all these effects have occurred in the daytime, it is considered that it may result from the filtering effect of the upward-propagating acoustic waves.

  16. Frequency analysis technology in laser Doppler velocimeter%激光多普勒测速仪中的频谱分析技术

    Institute of Scientific and Technical Information of China (English)

    刘帆; 金世龙

    2012-01-01

    A new method of signal processing was proposed in order to eliminate the noise interference and enhance the measurement accuracy of laser Doppler velocimeter (LDV). The frequency spectrum zooming and frequency spectrum correction technology were applied in the signal detection system of LDV. Basic principle of frequency analysis algorithms was briefly introduced, and then spectrum simulations of ideal sinusoidal signals were studied based on these algorithms. Goertzel zooming method and ratio correcting method were applied in realtime Doppler signal measurement. The simulation and experimental results indicate that resolution of frequency spectrum can be improved by frequency spectrum zooming technology and the accuracy of signal processing can be greatly improved by frequency spectrum correction technology. The frequency spectrum resolution and measurement accuracy of LDV system with the frequency analysis technology can be obviously improved. This application creates conditions for the design of high accuracy LDV.%为了提高激光多普勒测速仪的测速精度,将频谱分析技术应用于多普勒信号的处理中,先对信号进行频谱细化,再对细化后的频谱进行校正.阐述了几种常见的频谱细化和频谱校正算法的基本原理,并对它们的频谱分析精度和运算量进行了比较.在Matlab平台上将它们应用于理想正弦信号进行仿真,比较了各种算法的优缺点,最后将频谱细化和频谱校正技术应用于实测多普勒信号的处理中.仿真和实验结果表明:频谱细化技术可以大大提高激光多普勒信号的频谱分辨率,频谱校正技术可以准确地校正多普勒频率,减小信号处理的误差.将其运用于激光多普勒测速仪中切实可行,为设计高精度的激光多普勒测速仪创造了条件.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-05-01

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

  18. An acoustic spanner and its associated rotational Doppler shift

    Energy Technology Data Exchange (ETDEWEB)

    Skeldon, K D; Wilson, C; Edgar, M; Padgett, M J [Department of Physics and Astronomy, University of Glasgow, Glasgow (United Kingdom)

    2008-01-15

    Light carries a spin angular momentum associated with its polarization and an orbital angular momentum arising from its phase cross-section. Sound, being a longitudinal wave, carries no spin component but can carry an orbital component of angular momentum when endowed with an appropriate phase structure. Here, we use a circular array of loudspeakers driven at a common angular frequency {omega}{sub s} but with an azimuthally changing phase delay to create a sound wave with helical phase fronts described by exp (il{theta}). Such waves are predicted to have an orbital angular momentum to energy ratio of l/{omega}{sub s}. We confirm this angular momentum content by measuring its transfer to a suspended 60 cm diameter acoustic absorbing tile. The resulting torque on the tile ({approx}6.1x10{sup -6} Nm) is measured from observation of the motion for various torsional pendulums. Furthermore, we confirm the helical nature of the acoustic beam by observing the rotational Doppler shift, which results from a rotation between source and observer of angular velocity {omega}{sub r}. We measure Doppler shifted frequencies of {omega}{sub s}{+-}l{omega}{sub r} depending on the direction of relative rotation.

  19. A New Underwater Acoustic Navigation Method Based on the Doppler Principle

    Directory of Open Access Journals (Sweden)

    Jinsong Tang

    2013-07-01

    Full Text Available In this paper, a new underwater acoustic navigation method is proposed, which is named from Doppler Acoustic Omnirange Beacon (DAOB. It is borrowed from the idea of Doppler VHF Omnirange (DVOR and based on the Doppler principle. The cause of Doppler effect in the received signal is the motion or position change of one or two sources. The effect of multipath is analyzed, and an improved signal form is presented to solve the rigorous multipath environment underwater. Some simulation is presented to verify the performance.    

  20. Buoyancy package for self-contained acoustic doppler current profiler mooring

    Digital Repository Service at National Institute of Oceanography (India)

    Venkatesan, R.; Krishnakumar, V.

    A buoyancy package for self-contained Acoustic Doppler Current Profiler(SC-ADCP 1200 RD instruments USA) was designed and fabricated indigenously, for subsurface mooring in coastal waters. The system design is discussed. The design to keep SC...

  1. Acoustic Doppler Current Profiling near Myrtle Bend, June 3, 2013, Kootenai River near Bonners Ferry, ID

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Acoustic doppler current profiling (ADCP) data was collected to describe streamflow characteristics including total streamflow, velocity magnitude and secondary...

  2. Acoustic Doppler Current Profiling near Shorty's Island, June 1, 2012, Kootenai River near Bonners Ferry, ID

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — An Acoustic Doppler Current Profiler (ADCP) was used to survey streamflow characteristics including total streamflow, velocity magnitude and secondary flow...

  3. River Bed Sediment Classification Using Acoustic Doppler Profiler

    Science.gov (United States)

    Shields, F. D.

    2008-12-01

    Restoration or rehabilitation of degraded stream and river habitats requires definition of a target condition and preferably post-implementation monitoring to gage progress toward the target. Stream habitat has been characterized by computing statistics based on measurements of water depth and velocity at each point of a horizontal grid. In many cases stream bed type and cover, both qualitatively assessed, were included as additional grid variables. Resultant statistics describing the central tendency, variability and spatial distribution of these three or four variables and their combinations have been used to explain key differences between more- and less-degraded streams and to infer biotic responses. Usually the required data are collected by wading observers, but application to larger rivers is problematic. Collection of water depth and velocity information may be automated across a wide range of stream sizes using an acoustic Doppler profiler (aDp). Herein we suggest that aDp data may also be used to infer bed hardness and thus type by extracting the return signal strength from the bottom track signal and using this information to compute the echo intensity at the bed. A method for computing echo intensity, along with key assumptions is presented. Echo intensity is computed for a range of river environments and related to the size and related characteristics of bed material. Habitat maps for river reaches depicting water depth, velocity and bed type developed from aDp data sets are presented.

  4. Acoustic Doppler Current Profiler Data Processing System manual [ADCP

    Science.gov (United States)

    Cote, Jessica M.; Hotchkiss, Frances S.; Martini, Marinna; Denham, Charles R.; revisions by Ramsey, Andree L.; Ruane, Stephen

    2000-01-01

    This open-file report describes the data processing software currently in use by the U.S. Geological Survey (USGS), Woods Hole Coastal and Marine Science Center (WHCMSC), to process time series of acoustic Doppler current data obtained by Teledyne RD Instruments Workhorse model ADCPs. The Sediment Transport Instrumentation Group (STG) at the WHCMSC has a long-standing commitment to providing scientists high quality oceanographic data published in a timely manner. To meet this commitment, STG has created this software to aid personnel in processing and reviewing data as well as evaluating hardware for signs of instrument malfunction. The output data format for the data is network Common Data Form (netCDF), which meets USGS publication standards. Typically, ADCP data are recorded in beam coordinates. This conforms to the USGS philosophy to post-process rather than internally process data. By preserving the original data quality indicators as well as the initial data set, data can be evaluated and reprocessed for different types of analyses. Beam coordinate data are desirable for internal and surface wave experiments, for example. All the code in this software package is intended to run using the MATLAB program available from The Mathworks, Inc. As such, it is platform independent and can be adapted by the USGS and others for specialized experiments with non-standard requirements. The software is continuously being updated and revised as improvements are required. The most recent revision may be downloaded from: http://woodshole.er.usgs.gov/operations/stg/Pubs/ADCPtools/adcp_index.htm The USGS makes this software available at the user?s discretion and responsibility.

  5. The Doppler Effect based acoustic source separation for a wayside train bearing monitoring system

    Science.gov (United States)

    Zhang, Haibin; Zhang, Shangbin; He, Qingbo; Kong, Fanrang

    2016-01-01

    Wayside acoustic condition monitoring and fault diagnosis for train bearings depend on acquired acoustic signals, which consist of mixed signals from different train bearings with obvious Doppler distortion as well as background noises. This study proposes a novel scheme to overcome the difficulties, especially the multi-source problem in wayside acoustic diagnosis system. In the method, a time-frequency data fusion (TFDF) strategy is applied to weaken the Heisenberg's uncertainty limit for a signal's time-frequency distribution (TFD) of high resolution. Due to the Doppler Effect, the signals from different bearings have different time centers even with the same frequency. A Doppler feature matching search (DFMS) algorithm is then put forward to locate the time centers of different bearings in the TFD spectrogram. With the determined time centers, time-frequency filters (TFF) are designed with thresholds to separate the acoustic signals in the time-frequency domain. Then the inverse STFT (ISTFT) is taken and the signals are recovered and filtered aiming at each sound source. Subsequently, a dynamical resampling method is utilized to remove the Doppler Effect. Finally, accurate diagnosis for train bearing faults can be achieved by applying conventional spectrum analysis techniques to the resampled data. The performance of the proposed method is verified by both simulated and experimental cases. It shows that it is effective to detect and diagnose multiple defective bearings even though they produce multi-source acoustic signals.

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  7. A Comparison of the Electromagnetic and Acoustic Doppler Effects Using Geometrical Diagrams

    Science.gov (United States)

    Bokor, Nandor

    2009-01-01

    Students often find the difference in the electromagnetic and the acoustic Doppler formulae somewhat puzzling. As is shown below, geometrical diagrams and the concept of "event"--a point in spacetime having coordinates (x,y,z,t)--can be a useful and simple way to explain the physical background behind the fundamental differences between the two…

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  9. Quantified turbulent diffusion of suspended sediment using acoustic Doppler current profilers

    NARCIS (Netherlands)

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

    2013-01-01

    Collocated profiles of the Reynolds stress tensor and eddy covariance fluxes are obtained to derive vertical profiles of turbulent momentum and sediment diffusivity in a tidal river, using coupled acoustic Doppler current profilers (ADCPs). Shear and normal stresses are obtained by combining the var

  10. On the use of horizontal acoustic doppler profilers for continuous bed shear stress monitoring

    NARCIS (Netherlands)

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

    2013-01-01

    Continuous monitoring of bed shear stress in large river systems may serve to better estimate alluvial sediment transport to the coastal ocean. Here we explore the possibility of using a horizontally deployed acoustic Doppler current profiler (ADCP) to monitor bed shear stress, applying a prescribed

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

    Digital Repository Service at National Institute of Oceanography (India)

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

    of Performance of SonTek Argonaut Acoustic Doppler Velocity Log in Tow Tank and Sea Antony Joseph, R. Madhan, Antonio Mascaranhas, R.G. Prabhu Desai, Vijaykumar, Mathew Dias, Suryakant Tengali, and Anand Methar National Institute of Oceanography, Dona Paula...

  12. HF Doppler Acoustic Imaging of the Ocean Surface and Interior

    Science.gov (United States)

    Pinkel, Robert; Smith, Jerome A.

    2004-11-01

    HF phased array Doppler sonar represents a new tool for obtaining Three-dimensional (r,q,t) images of the oceanic surface and interior velocity field. While the capabilities of the approach are unique, the design constraints are also unusual. Examples of both are presented in this work.

  13. A micro-Doppler sonar for acoustic surveillance in sensor networks

    Science.gov (United States)

    Zhang, Zhaonian

    Wireless sensor networks have been employed in a wide variety of applications, despite the limited energy and communication resources at each sensor node. Low power custom VLSI chips implementing passive acoustic sensing algorithms have been successfully integrated into an acoustic surveillance unit and demonstrated for detection and location of sound sources. In this dissertation, I explore active and passive acoustic sensing techniques, signal processing and classification algorithms for detection and classification in a multinodal sensor network environment. I will present the design and characterization of a continuous-wave micro-Doppler sonar to image objects with articulated moving components. As an example application for this system, we use it to image gaits of humans and four-legged animals. I will present the micro-Doppler gait signatures of a walking person, a dog and a horse. I will discuss the resolution and range of this micro-Doppler sonar and use experimental results to support the theoretical analyses. In order to reduce the data rate and make the system amenable to wireless sensor networks, I will present a second micro-Doppler sonar that uses bandpass sampling for data acquisition. Speech recognition algorithms are explored for biometric identifications from one's gait, and I will present and compare the classification performance of the two systems. The acoustic micro-Doppler sonar design and biometric identification results are the first in the field as the previous work used either video camera or microwave technology. I will also review bearing estimation algorithms and present results of applying these algorithms for bearing estimation and tracking of moving vehicles. Another major source of the power consumption at each sensor node is the wireless interface. To address the need of low power communications in a wireless sensor network, I will also discuss the design and implementation of ultra wideband transmitters in a three dimensional

  14. Use of Acoustic Doppler Instruments for Measuring Discharge in Streams with Appreciable Sediment Transport

    Science.gov (United States)

    Mueller, D.S.

    2002-01-01

    The use of Acoustic Doppler current profilers (ADCP) for measuring discharge in streams with sediment transport was discussed. The studies show that the acoustic frequency of an ADCP in combination with the sediment transport characteristics in a river causes the ADCP bottom-tracking algorithms to detect a moving bottom. A moving bottom causes bottom-tracking-referenced water velocities and discharges to be biased low. The results also show that the use of differential global positioning system (DGPS) data allows accurate measurement of water velocities and discharges in such cases.

  15. Gulf stream velocity structure through combined inversion of hydrographic and acoustic Doppler data

    Science.gov (United States)

    Pierce, S. D.

    1986-01-01

    Near-surface velocities from an acoustic Doppler instrument are used in conjunction with CTD/O2 data to produce estimates of the absolute flow field off Cape Hatteras. The data set consists of two transects across the Gulf Stream made by the R/V Endeavor cruise EN88 in August 1982. An inverse procedure is applied which makes use of both the acoustic Doppler data and property conservation constraints. Velocity sections at approximately 73 deg. W and 71 deg. W are presented with formal errors of 1-2 cm/s. The net Gulf Stream transports are estimated to be 116 + or - 2 Sv across the south leg and 161 + or - 4 Sv across the north. A Deep Western Boundary Current transport of 4 + or - 1 Sv is also estimated. While these values do not necessarily represent the mean, they are accurate estimates of the synoptic flow field in the region.

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

    Directory of Open Access Journals (Sweden)

    Tran MinhHai

    2016-01-01

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

  17. Field evaluation of boat-mounted acoustic Doppler instruments used to measure streamflow

    Science.gov (United States)

    Mueller, D.S.

    2003-01-01

    The use of instruments based on the Doppler principle for measuring water velocity and computing discharge is common within the U.S. Geological Survey (USGS). The instruments and software have changed appreciably during the last 5 years; therefore, the USGS has begun field validation of the instruments used to make discharge measurements from a moving boat. Instruments manufactured by SonTek/YSI and RD Instruments, Inc. were used to collect discharge data at five different sites. One or more traditional discharge measurements were made using a Price AA current meter and standard USGS procedures concurrent with the acoustic instruments at each site. Discharges measured with the acoustic instruments were compared with discharges measured with Price AA current meters and the USGS stage-discharge rating for each site. The mean discharges measured by each acoustic instrument were within 5 percent of the Price AA-based measurement and (or) discharge from the stage-discharge rating.

  18. Contribution to the development of a Doppler global velocimeter for applications in turbomachinery; Contribution au developpement d'un velocimetre global a effet doppler en vue de l'application aux turbomachines

    Energy Technology Data Exchange (ETDEWEB)

    Buchet, H.

    2002-03-15

    Research in turbomachinery requires to develop CFD code as well as experimental device. Measurements are of prime important to set testing bench and access unsteady 3D velocimetry field in rotating parts. Since 1996, DGV technique (Doppler Global Velocimetry) has been developed at ONERA-Toulouse. This technique measure frequency shift caused by Doppler effect. To be applied in turbomachinery, this new method must be compared with PIV. As a reference case, a flow which geometry is comparable to that of a compressor blade grid has been chosen. Tests have been performed at Laboratoire Aerodynamique de Supaero in a transonic wind tunnel on an isolated profile. Wake has been characterised with the two different methods by measuring velocity average flow field. Results are promising and justify further development of the system.(author)

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

    Science.gov (United States)

    Sellar, Brian; Harding, Samuel; Richmond, Marshall

    2015-08-01

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

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

    Science.gov (United States)

    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. Estimating stream discharge using stage and multi-level acoustic Doppler velocimetry

    DEFF Research Database (Denmark)

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

    obtained from an Acoustic Doppler Current Profiler (ADCP) and with discharge values derived by the Danish Water Authority by traditional stage-discharge analysis. The novelty of this approach is that the velocity gradient is implemented as a marker for hydraulic changes in the hydrograph estimation......, without explicit use of cross sectional area and cross sectional average velocity. The initial results show good agreement between the ADCP discharge measurements and the discharge values predicted from the stage-velocity method and suggest superiority of the stage-velocity method during abrupt changes...

  2. Monitoring suspended sediment transport in an ice-affected river using acoustic Doppler current profilers

    Science.gov (United States)

    Moore, S. A.; Ghareh Aghaji Zare, S.; Rennie, C. D.; Ahmari, H.; Seidou, O.

    2013-12-01

    Quantifying sediment budgets and understanding the processes which control fluvial sediment transport is paramount to monitoring river geomorphology and ecological habitat. In regions that are subject to freezing there is the added complexity of ice. River ice processes impact flow distribution, water stage and sediment transport. Ice processes typically have the largest impact on sediment transport and channel morphodynamics when ice jams occur during ice cover formation and breakup. Ice jams may restrict flow and cause local acceleration when released. Additionally, ice can mechanically scour river bed and banks. Under-ice sediment transport measurements are lacking due to obvious safety and logistical reasons, in addition to a lack of adequate measurement techniques. Since some rivers can be covered in ice during six months of the year, the lack of data in winter months leads to large uncertainty in annual sediment load calculations. To address this problem, acoustic profilers are being used to monitor flow velocity, suspended sediment and ice processes in the Lower Nelson River, Manitoba, Canada. Acoustic profilers are ideal for under-ice sediment flux measurements since they can be operated autonomously and continuously, they do not disturb the flow in the zone of measurement and acoustic backscatter can be related to sediment size and concentration. In March 2012 two upward-facing profilers (1200 kHz acoustic Doppler current profiler, 546 KHz acoustic backscatter profiler) were installed through a hole in the ice on the Nelson River, 50 km downstream of the Limestone Generating Station. Data were recorded for four months, including both stable cover and breakup periods. This paper presents suspended sediment fluxes calculated from the acoustic measurements. Velocity data were used to infer the vertical distribution of sediment sizes and concentrations; this information was then used in the interpretation of the backscattered intensity data. It was found that

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

    DEFF Research Database (Denmark)

    Zhao, Bo; Blanke, Mogens; Skjetne, Roger

    2012-01-01

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

  4. Variance of discharge estimates sampled using acoustic Doppler current profilers from moving boats

    Science.gov (United States)

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

    2012-01-01

    This paper presents a model for quantifying the random errors (i.e., variance) of acoustic Doppler current profiler (ADCP) discharge measurements from moving boats for different sampling times. The model focuses on the random processes in the sampled flow field and has been developed using statistical methods currently available for uncertainty analysis of velocity time series. Analysis of field data collected using ADCP from moving boats from three natural rivers of varying sizes and flow conditions shows that, even though the estimate of the integral time scale of the actual turbulent flow field is larger than the sampling interval, the integral time scale of the sampled flow field is on the order of the sampling interval. Thus, an equation for computing the variance error in discharge measurements associated with different sampling times, assuming uncorrelated flow fields is appropriate. The approach is used to help define optimal sampling strategies by choosing the exposure time required for ADCPs to accurately measure flow discharge.

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

    Science.gov (United States)

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

    2002-01-01

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

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

    Science.gov (United States)

    Kim, D.; Winkler, M.; Muste, M.

    2015-06-01

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

  7. Fluorescent image tracking velocimeter

    Science.gov (United States)

    Shaffer, Franklin D.

    1994-01-01

    A multiple-exposure fluorescent image tracking velocimeter (FITV) detects and measures the motion (trajectory, direction and velocity) of small particles close to light scattering surfaces. The small particles may follow the motion of a carrier medium such as a liquid, gas or multi-phase mixture, allowing the motion of the carrier medium to be observed, measured and recorded. The main components of the FITV include: (1) fluorescent particles; (2) a pulsed fluorescent excitation laser source; (3) an imaging camera; and (4) an image analyzer. FITV uses fluorescing particles excited by visible laser light to enhance particle image detectability near light scattering surfaces. The excitation laser light is filtered out before reaching the imaging camera allowing the fluoresced wavelengths emitted by the particles to be detected and recorded by the camera. FITV employs multiple exposures of a single camera image by pulsing the excitation laser light for producing a series of images of each particle along its trajectory. The time-lapsed image may be used to determine trajectory and velocity and the exposures may be coded to derive directional information.

  8. Calibration of sound velocimeter in pure water

    Science.gov (United States)

    Li, Zhiwei; Zhang, Baofeng; Li, Tao; Zhu, Junchao; Xie, Ziming

    2016-01-01

    Accurate measurement of sound speed is important to calibrate a sound velocity profiler which provides real-time sound velocity to the sonar equipment in oceanographic survey. The sound velocity profiler calculates the sound speed by measuring the time-of-flight of a 1 MHz single acoustic pulse to travel over about 300 mm path. A standard sound velocimeter instrument was invited to calibrate the sound velocity profiler in pure water at temperatures of 278,283, 288, 293, 298, 303 and 308K in a thermostatic vessel at one atmosphere. The sound velocity profiler was deployed in the thermostatic vessel alongside the standard sound velocimeter instrument and two platinum resistance thermometers (PRT) which were calibrated to 0.002k by comparison with a standard PRT. Time of flight circuit board was used to measure the time-of-flight to 22 picosecond precision. The sound speed which was measured by the sound velocity profiler was compared to the standard sound speed calculated by UNESCO to give the laboratory calibration coefficients and was demonstrated agreement with CTD-derived sound speed using Del Grosso's seawater equation after removing a bias.

  9. Online Doppler Effect Elimination Based on Unequal Time Interval Sampling for Wayside Acoustic Bearing Fault Detecting System.

    Science.gov (United States)

    Ouyang, Kesai; Lu, Siliang; Zhang, Shangbin; Zhang, Haibin; He, Qingbo; Kong, Fanrang

    2015-08-27

    The railway occupies a fairly important position in transportation due to its high speed and strong transportation capability. As a consequence, it is a key issue to guarantee continuous running and transportation safety of trains. Meanwhile, time consumption of the diagnosis procedure is of extreme importance for the detecting system. However, most of the current adopted techniques in the wayside acoustic defective bearing detector system (ADBD) are offline strategies, which means that the signal is analyzed after the sampling process. This would result in unavoidable time latency. Besides, the acquired acoustic signal would be corrupted by the Doppler effect because of high relative speed between the train and the data acquisition system (DAS). Thus, it is difficult to effectively diagnose the bearing defects immediately. In this paper, a new strategy called online Doppler effect elimination (ODEE) is proposed to remove the Doppler distortion online by the introduced unequal interval sampling scheme. The steps of proposed strategy are as follows: The essential parameters are acquired in advance. Then, the introduced unequal time interval sampling strategy is used to restore the Doppler distortion signal, and the amplitude of the signal is demodulated as well. Thus, the restored Doppler-free signal is obtained online. The proposed ODEE method has been employed in simulation analysis. Ultimately, the ODEE method is implemented in the embedded system for fault diagnosis of the train bearing. The results are in good accordance with the bearing defects, which verifies the good performance of the proposed strategy.

  10. Online Doppler Effect Elimination Based on Unequal Time Interval Sampling for Wayside Acoustic Bearing Fault Detecting System

    Directory of Open Access Journals (Sweden)

    Kesai Ouyang

    2015-08-01

    Full Text Available The railway occupies a fairly important position in transportation due to its high speed and strong transportation capability. As a consequence, it is a key issue to guarantee continuous running and transportation safety of trains. Meanwhile, time consumption of the diagnosis procedure is of extreme importance for the detecting system. However, most of the current adopted techniques in the wayside acoustic defective bearing detector system (ADBD are offline strategies, which means that the signal is analyzed after the sampling process. This would result in unavoidable time latency. Besides, the acquired acoustic signal would be corrupted by the Doppler effect because of high relative speed between the train and the data acquisition system (DAS. Thus, it is difficult to effectively diagnose the bearing defects immediately. In this paper, a new strategy called online Doppler effect elimination (ODEE is proposed to remove the Doppler distortion online by the introduced unequal interval sampling scheme. The steps of proposed strategy are as follows: The essential parameters are acquired in advance. Then, the introduced unequal time interval sampling strategy is used to restore the Doppler distortion signal, and the amplitude of the signal is demodulated as well. Thus, the restored Doppler-free signal is obtained online. The proposed ODEE method has been employed in simulation analysis. Ultimately, the ODEE method is implemented in the embedded system for fault diagnosis of the train bearing. The results are in good accordance with the bearing defects, which verifies the good performance of the proposed strategy.

  11. Online Doppler Effect Elimination Based on Unequal Time Interval Sampling for Wayside Acoustic Bearing Fault Detecting System.

    Science.gov (United States)

    Ouyang, Kesai; Lu, Siliang; Zhang, Shangbin; Zhang, Haibin; He, Qingbo; Kong, Fanrang

    2015-01-01

    The railway occupies a fairly important position in transportation due to its high speed and strong transportation capability. As a consequence, it is a key issue to guarantee continuous running and transportation safety of trains. Meanwhile, time consumption of the diagnosis procedure is of extreme importance for the detecting system. However, most of the current adopted techniques in the wayside acoustic defective bearing detector system (ADBD) are offline strategies, which means that the signal is analyzed after the sampling process. This would result in unavoidable time latency. Besides, the acquired acoustic signal would be corrupted by the Doppler effect because of high relative speed between the train and the data acquisition system (DAS). Thus, it is difficult to effectively diagnose the bearing defects immediately. In this paper, a new strategy called online Doppler effect elimination (ODEE) is proposed to remove the Doppler distortion online by the introduced unequal interval sampling scheme. The steps of proposed strategy are as follows: The essential parameters are acquired in advance. Then, the introduced unequal time interval sampling strategy is used to restore the Doppler distortion signal, and the amplitude of the signal is demodulated as well. Thus, the restored Doppler-free signal is obtained online. The proposed ODEE method has been employed in simulation analysis. Ultimately, the ODEE method is implemented in the embedded system for fault diagnosis of the train bearing. The results are in good accordance with the bearing defects, which verifies the good performance of the proposed strategy. PMID:26343657

  12. Velocity Data collected from moored Hull-Mounted Acoustic Doppler Current Profilers positioned in Vieques Sound and Virgin Passage in the US Caribbean

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Velocity data were collected from Hull-Mounted Acoustic Doppler Current Profilers moored across Virgin Passage between Culebra, Puerto Rico and St. Thomas, USVI,...

  13. Ocean currents measured by Shipboard Acoustic Doppler Current Profilers (SADCP) from global oceans accumulated at Joint Archive for SADCP from 2004 to 2013 (NODC Accession 0123302)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Absolute U- and V-component ocean current vectors from Shipboard Acoustic Doppler Current Profilers (SADCP), as both a high-frequency sampling (nominally 5 minutes...

  14. CRED Acoustic Doppler Profiler (ADP); NWHI, MID; Long: -177.42181, Lat: 28.21826 (WGS84); Sensor Depth: 1.83m; Data Range: 20080926-20090321.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Island Fisheries Science Center Acoustic Doppler Profilers (ADP) provide a time series of water current...

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

    International Nuclear Information System (INIS)

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

  16. Coupling airborne laser scanning and acoustic Doppler current profiler data to model stream rating curves

    Science.gov (United States)

    Lam, N.; Lyon, S. W.; Kean, J. W.

    2015-12-01

    The rating curve enables the translation of water depth into discharge through a reference cross section. Errors in estimating stream channel geometry can therefore result in increased discharge uncertainty. This study investigates coupling national-scale airborne laser scanning (ALS) and acoustic Doppler current profiler (ADCP) bathymetric survey data for generating stream rating curves. Specifically, stream channel geometries were generated from coupled ALS and ADCP scanning data collected for a well-monitored site located in northern Sweden. These data were used to define the hydraulic geometry required by a physically-based 1-D hydraulic model. The results of our study demonstrate that the effects of potential scanning data errors on the model generated rating curve were less than the uncertainties due to stream gauging measurements and empirical rating curve fitting. Further analysis of the ALS data showed that an overestimation of the streambank elevation (the main scanning data error) was primarily due to vegetation that could be adjusted for through a root-mean-square-error bias correction. We consider these findings encouraging as hydrometric agencies can potentially leverage national-scale ALS and ADCP instrumentation to reduce the cost and effort required for maintaining and establish rating curves at gauging stations.

  17. Prospects for in vivo blood velocimetry using acoustic resolution photoacoustic Doppler

    Science.gov (United States)

    Brunker, J.; Beard, P.

    2016-03-01

    Acoustic resolution photoacoustic Doppler flowmetry (AR-PAF) is a technique that has the potential to overcome the spatial resolution and depth penetration limitations of current blood flow measuring methods. Previous work has shown the potential of the technique using blood-mimicking phantoms, but it has proved difficult to make accurate measurements in blood, and thus in vivo application has not yet been possible. One explanation for this difficulty is that whole blood is insufficiently heterogeneous. Through experimental measurements in red blood cell suspensions of different concentrations, as well as in whole blood, we provide new insight and evidence that refutes this assertion. We show that the velocity measurement accuracy is influenced by bandlimiting not only due to the detector frequency response, but also due to spatial averaging of absorbers within the detector field-of-view. In addition, there is a detrimental effect of limited light penetration, but this can be mitigated by selecting less attenuated wavelengths of light, and also by employing range-gating signal processing. By careful choice of these parameters as well as the detector centre frequency, bandwidth and field-of-view, it is possible to make AR-PAF measurements in whole blood using transducers with bandwidths in the tens of MHz range. These findings have profound implications for the prospects of making deep tissue measurements of blood flow relevant to the study of microcirculatory abnormalities associated with cancer, diabetes, atherosclerosis and other conditions.

  18. Correction of Teledyne Acoustic Doppler Current Profiler (ADCP) Bottom-Track Range Measurements for Instrument Pitch and Roll

    CERN Document Server

    Woodgate, Rebecca A

    2011-01-01

    The Workhorse Acoustic Doppler Current Profiler (ADCP) manufactured by Teledyne RD Instruments (RDI) uses a "Bottom-Tracking" algorithm to yield data intended to represent distance to the bottom. However, current RDI software processing does not take into account the pitch and roll of the instrument. This technical note outlines post-deployment computations required to correct the reported Bottom-Track Ranges for instrument pitch and roll in the scenario where the ADCP is upward-looking with Bottom-Tracking being used to estimate distance to the surface.

  19. Acoustic Doppler current profiling from the JGOFS Arabian Sea cruises aboard the RV T.G. Thompson

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H.S.; Flagg, C.N.; Shi, Y. [Brookhaven National Lab., Upton, NY (United States). Oceanographic and Atmospheric Sciences Div.

    1996-12-01

    Acoustic Doppler current profiler (ADCP) data is part of the core data for the US JGOFS Arabian Sea project, along with hydrographic and nutrient data. Seventeen cruises are scheduled to take place between September 1994 and January 1996 on the R/V T.G. Thompson. Seven of the cruises follow a standard cruise track, taking hydrographic, chemical and biological measurements. The rest of the cruises, which take place generally within the standard cruise region defined by a set track, are for the deployment and recovery of moored equipment and towing of a SeaSoar. Detailed description of ADCP hardware, the AutoADCP data acquisition system, and the collection of navigation and compass data on the Thompson is documented in Section 2. Followed by data collection for each cruise together with a cruise track, Section 3 presents the processing and analysis of velocity and acoustic backscatter intensity data. Section 5 shows results of profile quality diagnosis.

  20. QRev—Software for computation and quality assurance of acoustic doppler current profiler moving-boat streamflow measurements—User’s manual for version 2.8

    Science.gov (United States)

    Mueller, David S.

    2016-05-12

    The software program, QRev computes the discharge from moving-boat acoustic Doppler current profiler measurements using data collected with any of the Teledyne RD Instrument or SonTek bottom tracking acoustic Doppler current profilers. The computation of discharge is independent of the manufacturer of the acoustic Doppler current profiler because QRev applies consistent algorithms independent of the data source. In addition, QRev automates filtering and quality checking of the collected data and provides feedback to the user of potential quality issues with the measurement. Various statistics and characteristics of the measurement, in addition to a simple uncertainty assessment are provided to the user to assist them in properly rating the measurement. QRev saves an extensible markup language file that can be imported into databases or electronic field notes software. The user interacts with QRev through a tablet-friendly graphical user interface. This report is the manual for version 2.8 of QRev.

  1. QRev—Software for computation and quality assurance of acoustic doppler current profiler moving-boat streamflow measurements—User’s manual for version 2.8

    Science.gov (United States)

    Mueller, David S.

    2016-01-01

    The software program, QRev computes the discharge from moving-boat acoustic Doppler current profiler measurements using data collected with any of the Teledyne RD Instrument or SonTek bottom tracking acoustic Doppler current profilers. The computation of discharge is independent of the manufacturer of the acoustic Doppler current profiler because QRev applies consistent algorithms independent of the data source. In addition, QRev automates filtering and quality checking of the collected data and provides feedback to the user of potential quality issues with the measurement. Various statistics and characteristics of the measurement, in addition to a simple uncertainty assessment are provided to the user to assist them in properly rating the measurement. QRev saves an extensible markup language file that can be imported into databases or electronic field notes software. The user interacts with QRev through a tablet-friendly graphical user interface. This report is the manual for version 2.8 of QRev.

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

    Science.gov (United States)

    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

  3. Uncertainty of canal seepage losses estimated using flowing water balance with acoustic Doppler devices

    Science.gov (United States)

    Martin, Chad A.; Gates, Timothy K.

    2014-09-01

    Seepage losses from unlined irrigation canals amount to a large fraction of the total volume of water diverted for agricultural use, posing problems to both water conservation and water quality. Quantifying these losses and identifying areas where they are most prominent are crucial for determining the severity of seepage-related complications and for assessing the potential benefits of seepage reduction technologies and materials. A relatively easy and inexpensive way to estimate losses over an extensive segment of a canal is the flowing water balance, or inflow-outflow, method. Such estimates, however, have long been considered fraught with ambiguity due both to measurement error and to spatial and temporal variability. This paper presents a water balance analysis that evaluates uncertainty in 60 tests on two typical earthen irrigation canals. Monte Carlo simulation is used to account for a number of different sources of uncertainty. Issues of errors in acoustic Doppler flow measurement, in water level readings, and in evaporation estimates are considered. Storage change and canal wetted perimeter area, affected by variability in the canal prism, as well as lagged vs. simultaneous measurements of discharge at the inflow and outflow ends also are addressed. Mean estimated seepage loss rates for the tested canal reaches ranged from about -0.005 (gain) to 0.110 m3 s-1 per hectare of canal wetted perimeter (or -0.043 to 0.95 m d-1) with estimated probability distributions revealing substantial uncertainty. Across the tests, the average coefficient of variation was about 240% and the average 90th inter-percentile range was 0.143 m3 s-1 per hectare (1.24 m d-1). Sensitivity analysis indicates that while the predominant influence on seepage uncertainty is error in measured discharge at the upstream and downstream ends of the canal test reach, the magnitude and uncertainty of storage change due to unsteady flow also is a significant influence. Recommendations are

  4. Doppler effect for sound emitted by a moving airborne source and received by acoustic sensors located above and below the sea surface.

    Science.gov (United States)

    Ferguson, B G

    1993-12-01

    The acoustic emissions from a propeller-driven aircraft are received by a microphone mounted just above ground level and then by a hydrophone located below the sea surface. The dominant feature in the output spectrum of each acoustic sensor is the spectral line corresponding to the propeller blade rate. A frequency estimation technique is applied to the acoustic data from each sensor so that the Doppler shift in the blade rate can be observed at short time intervals during the aircraft's transit overhead. For each acoustic sensor, the observed variation with time of the Doppler-shifted blade rate is compared with the variation predicted by a simple ray-theory model that assumes the atmosphere and the sea are distinct isospeed sound propagation media separated by a plane boundary. The results of the comparison are shown for an aircraft flying with a speed of about 250 kn at altitudes of 500, 700, and 1000 ft.

  5. 自适应滤波技术在激光多普勒测速仪中的应用%Application of least mean square adaptive filter technology in laser Doppler velocimeter

    Institute of Scientific and Technical Information of China (English)

    刘帆; 金世龙; 周健

    2012-01-01

    Noise always exists in photoelectric signal detected by laser Doppler velocimcter (LDV). A new method of signal processing was proposed in order to eliminate the noise interference and enhance the measurement accuracy of LDV. The least mean square(LMS) adaptive filter technology was applied in the signal detection system of LDV. By processing the Doppler signal, we greatly minished the interference of noise. The simulation ari3 experiment results indicate that this technology effectively increases the signal to noise ratio(SNR) of Doppler signal, reduces.the system's demand for SNR of signal, and obviously improves the noiseproof ability, the sensibility,as well as the measurement accuracy of LDV system. This application creates conditions for the design of high accuracy LDV.%激光多普勒测速仪检测系统提取的光电信号中存在较大的噪声信号.为了消除这些噪声干扰,提高激光多普勒测速仪的测量精度,提出一种新的信号处理方法,将最小均方差自适应滤波技术应用于激光多普勒测量中,利用多普勒信号和噪声信号的统计特性,以最小均方误差估计为准则,最大程度地滤除噪声信号.阐述了最小均方差自适应滤波算法的基本原理,在MATLAB平台上将其应用于理想正弦信号进行仿真,并将其应用于实测多普勒信号的处理中.仿真和实验均表明,该技术可以有效抑制激光多普勒测量中的多频率噪声的干扰,大大提高多普勒信号的信噪比和测量精度,为设计高精度的激光多普勒测速仪创造了条件.

  6. Acoustic Doppler Current Profiler Measurements in the Tailrace at John Day Dam

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Chris B.; Dibrani, Berhon; Serkowski, John A.; Richmond, Marshall C.; Titzler, P. Scott; Dennis, Gary W.

    2006-01-30

    Acoustic Doppler current profilers (ADCPs) were used to measure water velocities in the tailrace at John Day Dam over a two-week period in February 2005. Data were collected by the Pacific Northwest National Laboratory for the Hydraulic Design Section, Portland District, U.S. Army Corps of Engineers (USACE). The objective of this project was therefore to collect field measurements of water velocities in the near-field draft tube exit zone as well as the far-field tailrace to be used for improving these models. Field data were collected during the project using five separate ADCPs. Mobile ADCP data were collected using two ADCPs mounted on two separate boats. Data were collected by either holding the boat on-station at pre-defined locations for approximately 10 minutes or in moving transect mode when the boat would move over large distances during the data collection. Results from the mobile ADCP survey indicated a complex hydrodynamic flow field in the tailrace downstream of John Day Dam. A large gyre was noted between the skeleton section of the powerhouse and non-spilling portion of the spillway. Downstream of the spillway, the spillway flow is constrained against the navigation lock guide wall, and large velocities were noted in this region. Downstream of the guide wall, velocities decreased as the spillway jet dispersed. Near the tailrace island, the flow split was measured to be approximately equal on Day 2 (25.4 kcfs spillway/123 kcfs total). However, approximately 60% of the flow passed along the south shore of the island on Day 1 (15.0 kcfs spillway/150 kcfs total). At a distance of 9000 ft downstream of the dam, flows had equalized laterally and were generally uniform over the cross section. The collection of water velocities near the draft tube exit of an operating turbine unit is not routine, and equipment capable of measuring 3D water velocities in these zones are at the forefront of hydraulic measurement technology. Although the feasibility of

  7. Long-term ferry-based observations of the suspended sediment fluxes through the Marsdiep inlet using acoustic Doppler current profilers

    NARCIS (Netherlands)

    Nauw, J.J.; Merckelbach, L.M.; Ridderinkhof, H.; van Aken, H.M.

    2014-01-01

    Long-term measurements with a hull mounted acoustic Doppler current profiler (ADCP) under the ferry, crossing the Marsdiep inlet between the mainland and the island of Texel (the Netherlands), were used to determine the volume flux and the flux of suspended particulate matter (SPM) through this inle

  8. Compensation of Linear Multiscale Doppler for OFDM-Based Underwater Acoustic Communication Systems

    Directory of Open Access Journals (Sweden)

    A. E. Abdelkareem

    2012-01-01

    Full Text Available In particular cases, such as acceleration, it is required to design a receiver structure that is capable of accomplishing time varying Doppler compensation. In this paper, two approaches are taken into consideration in order to estimate the symbol timing offset parameter. The first method employed to achieve an estimate of this particular parameter is based upon centroid localization and this prediction is reinforced by a second technique which utilises linear prediction, based on the assumption that the speed changes linearly during the OFDM symbol time. Subsequently, the two estimations of the symbol timing offset parameter are smoothed in order to obtain a fine tuned approximation of the Doppler scale. Additionally, the effects of weighting coefficients on smoothing the Doppler scale and on the performance of the receiver are also investigated. The proposed receiver is investigated, incorporating an improvement that includes fine tuning of the coarse timing synchronization in order to accommodate the time-varying Doppler. Based on this fine-tuned timing synchronization, an extension to the improved receiver is presented to assess the performance of two point correlations. The proposed algorithms' performances were investigated using real data obtained from an experiment that took place in the North Sea in 2009.

  9. Validation of HF radar probing of the vertical shear of surface currents by acoustic Doppler current profiler measurements

    Science.gov (United States)

    Ivonin, Dmitry V.; Broche, Pierre; Devenon, Jean-Luc; Shrira, Victor I.

    2004-04-01

    There exists no practical way of measuring vertical shear in the water just below the air/sea interface that contains information on air/water momentum fluxes. The paper is concerned with the validation of a recently proposed method of remote sensing of sea subsurface shear by means of a commonly used single-frequency HF radar based on the use of the second-order Bragg echo. To this end a dedicated field experiment was carried out off the French Mediterranean coast. In parallel with the HF radar probing, the independent simultaneous measurements of the subsurface shear profile were obtained by means of acoustic Doppler current profiler mounted on a floating platform, whose position was monitored by GPS. The comparison shows a fairly good agreement of the results (the discrepancy does not exceed 15%) and suggests a higher accuracy of the HF probing.

  10. Modeling laser velocimeter signals as triply stochastic Poisson processes

    Science.gov (United States)

    Mayo, W. T., Jr.

    1976-01-01

    Previous models of laser Doppler velocimeter (LDV) systems have not adequately described dual-scatter signals in a manner useful for analysis and simulation of low-level photon-limited signals. At low photon rates, an LDV signal at the output of a photomultiplier tube is a compound nonhomogeneous filtered Poisson process, whose intensity function is another (slower) Poisson process with the nonstationary rate and frequency parameters controlled by a random flow (slowest) process. In the present paper, generalized Poisson shot noise models are developed for low-level LDV signals. Theoretical results useful in detection error analysis and simulation are presented, along with measurements of burst amplitude statistics. Computer generated simulations illustrate the difference between Gaussian and Poisson models of low-level signals.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-01

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

  12. A New Approach to Teaching Human Cardiovascular Physiology Using Doppler Ultrasound.

    Science.gov (United States)

    Looker, T.

    1985-01-01

    Explains the principles of the Doppler ultrasound technique and reviews its potential applications to the teaching of cardiovascular physiology. Identifies the instrumentation needed for this technique; provides examples and illustrations of the waveforms from the ultrasound blood velocimeter. (ML)

  13. Signal transformation and processing of pulsed Doppler acoustic remote sensing system

    Institute of Scientific and Technical Information of China (English)

    赵松年; 熊小芸; 文峰

    1995-01-01

    Acoustic remote sensing is a principal method in the probing system of the atmospheric bounda-ry layer(ABL).Three effective methods for the wind profile obtained from transformation and processingof acoustic echo wave are provided,i.e.(i)convolution algorithm by separating segments;(ii)complex polesmodel and its spectral estimation and,(iii)tracking filtering phase locked loop.Under the bound condition inlimited data recording length or sampling number of recording data,the satisfactory resolution power of frequen-cy can be obtained.Because of the wide applications of VLSI circuit chip of high speed DSP,the threemethods discussed can be applied to radar and sonar systems.

  14. Synoptic Gulf Stream velocity profiles through simultaneous inversion of hydrographic and acoustic Doppler data

    Science.gov (United States)

    Joyce, T. M.; Wunsch, C.; Pierce, S. D.

    1986-01-01

    Data from a shipborne acoustic profiling device have been combined with conductivity, temperature, depth/O2 sections across the Gulf Stream to form estimates of the absolute flow fields. The procedure for the combination was a form of inverse method. The results suggest that at the time of the observations (June 1982) the net Gulf Stream transport off Hatteras was 107 + or - 11 Sv and that across a section near 72.5 W it had increased to 125 + or - 6 Sv. The transport of the deep western boundary current was 9 + or - 3 Sv. For comparison purposes an inversion was done using the hydrographic/O2 data alone as in previously published results and obtained qualitative agreement with the combined inversion. Inversion of the acoustic measurements alone, when corrected for instrument biases, leaves unacceptably large mass transport residuals in the deep water.

  15. Ocean currents measured by Shipboard Acoustic Doppler Current Profiler (SADCP) from global oceans as part of the Joint Archive for Shipboard ADCP holdings from 16 June 1985 to 22 July 2003 (NODC Accession 0001206)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Absolute U- and V-component ocean current vectors from Shipboard Acoustic Doppler Current Profilers (SADCP), as both a high frequency sampling (nominally 5 minutes...

  16. Ocean currents measured by Shipboard Acoustic Doppler Current Profiler (SADCP) from global oceans as part of the Joint Archive for Shipboard ADCP holdings from 16 June 1985 to 23 March 2001 (NCEI Accession 0000755)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Absolute U- and V-component ocean current vectors from Shipboard Acoustic Doppler Current Profilers (SADCP), as both a high frequency sampling (nominally 5 minutes...

  17. Ocean currents measured by Shipboard Acoustic Doppler Current Profiler (SADCP) from global oceans as part of the Joint Archive for SADCP holdings from 20 August 1999 to 13 May 2009 (NCEI Accession 0067774)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Absolute U- and V-component ocean current vectors from Shipboard Acoustic Doppler Current Profilers (SADCP), as both a high-frequency sampling (nominally 5 minutes...

  18. Ocean currents measured by Shipboard Acoustic Doppler Current Profiler (SADCP) from global oceans as part of the Joint Archive for Shipboard ADCP holdings from 13 September 1999 to 28 April 2007 (NCEI Accession 0036863)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Absolute U- and V-component ocean current vectors from Shipboard Acoustic Doppler Current Profilers (SADCP), as both a high frequency sampling (nominally 5 minutes...

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

    Science.gov (United States)

    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. Design and performance of acoustic planar array antenna for Doppler sodar

    Directory of Open Access Journals (Sweden)

    A.Kamalakumari

    2012-09-01

    Full Text Available The remote probing of the thermal structure and the wind velocity in the lower atmosphere requires highly directive antennas, which should have a half-power beam width of about ±10° (3-dB points, a 90°-sidelobe suppression of at least 40 dB, little volume reverberation, low wind sensitivity, and be made of weatherproofmaterial. In this paper, various off-axis planar antennas have been built and acoustically evaluated the design aspects, measured results and field patterns of an 8x8 acoustic planar array antennas are described. Tweeter elements are arranged in a planar geometry and are capable of transmitting vertical polarization when placed nearly horizontal, are appropriate for the sodar applications. The performance of 8x8 planar antennas are tested experimentally for the frequencies from 1.8KHz to 4KHz at elevation angles ranging between 0 to 180°.The experimental results, as well as the measured beam widths and field patterns of this antennas, are presented.

  1. Acoustic Doppler current profiling from the JGOFS Arabian sea cruises aboard the RV T.G. Thompson

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Sook; Flagg, C.N.; Shi, Yan

    1996-06-01

    Acoustic Doppler current profiler (ADCP) data is part of the core data for the U.S. JGOFS Arabian Sea project, along with hydrographic and nutrient data. Seventeen cruises are scheduled to take place between September 1994 and January 1996 on the R/V T.G. Thompson. They are numbered consecutively from the ship`s commissioning with the first JGOFS cruise designated TN039. Table 1 lists start and end dates of each cruise with its mission. All but the first cruise have been or will be staged from Muscat, Oman. Each cruise is scheduled for a duration of between two weeks and one month. Seven of the cruises, referred to as process cruises, follow a standard cruise track, taking hydrographic, chemical and biological measurements. The rest of the cruises, which take place generally within the standard cruise region defined by a set track, are for the deployment and recovery of moored equipments and towing of a SeaSoar. ADCP data are collected using an autonomous data acquisition system developed for ship-of-opportunity cruises, named the AutoADCP system. The system is an extension of RD instrument`s DAS version 2.48 using enhancements made possible with {open_quotes}user-exit{close_quotes} programs. It makes it possible to collect ADCP data without the constant monitoring usually necessary and insures constant data coverage and uniform data quality.

  2. Observations of near-inertial waves in acoustic Doppler current profiler measurements made during the Mixed Layer Dynamics Experiment

    Science.gov (United States)

    Chereskin, T. K.; Levine, M. D.; Harding, A. J.; Regier, L. A.

    1989-06-01

    Measurements of upper ocean shear made during the Mixed Layer Dynamics Experiment (MILDEX) provide evidence of large horizontal scale motion at near-inertial frequency. The measurements consist of shipboard acoustic Doppler current profiles. Four large-scale spatial surveys of 2-4 days duration were made by the R/V Wecoma as a set of boxes approximately 60 km per side around a drifting current meter buoy. Velocity time series from the drifting buoy and from sonar measurements made from FLIP also indicated the presence of motions at near-inertial frequency. Horizontal length and time scales of the motion are estimated from the phase of the shear vector measured during the spatial surveys. Estimates of the length scale of the waves range from 500 to 1000 km, and the frequency is approximately 1.1f. The behavior of the phase is found to be consistent with a model of narrow-band inertial waves with vertical structure such that there is a zero crossing in velocity at the base of the mixed layer (40-60 m).

  3. A Fourier Optical Model for the Laser Doppler Velocimeter

    DEFF Research Database (Denmark)

    Lading, Lars

    1972-01-01

    The treatment is based on a fourier optical model. It is shown how the various configurations (i.e. ldquodifferential moderdquo and reference beam mode with both one and two incident beams) are incorporated in the model, and how it can be extended to three dimensions. The particles are represented...

  4. Phononic crystal surface mode coupling and its use in acoustic Doppler velocimetry.

    Science.gov (United States)

    Cicek, Ahmet; Salman, Aysevil; Kaya, Olgun Adem; Ulug, Bulent

    2016-02-01

    It is numerically shown that surface modes of two-dimensional phononic crystals, which are Bloch modes bound to the interface between the phononic crystal and the surrounding host, can couple back and forth between the surfaces in a length scale determined by the separation of two surfaces and frequency. Supercell band structure computations through the finite-element method reveal that the surface band of an isolated surface splits into two bands which support either symmetric or antisymmetric hybrid modes. When the surface separation is 3.5 times the lattice constant, a coupling length varying between 30 and 48 periods can be obtained which first increases linearly with frequency and, then, decreases rapidly. In the linear regime, variation of coupling length can be used as a means of measuring speeds of objects on the order of 0.1m/s by incorporating the Doppler shift. Speed sensitivity can be improved by increasing surface separation at the cost of larger device sizes. PMID:26565078

  5. Acoustic and Doppler radar detection of buried land mines using high-pressure water jets

    Science.gov (United States)

    Denier, Robert; Herrick, Thomas J.; Mitchell, O. Robert; Summers, David A.; Saylor, Daniel R.

    1999-08-01

    The goal of the waterjet-based mine location and identification project is to find a way to use waterjets to locate and differentiate buried objects. When a buried object is struck with a high-pressure waterjets, the impact will cause characteristic vibrations in the object depending on the object's shape and composition. These vibrations will be transferred to the ground and then to the water stream that is hitting the object. Some of these vibrations will also be transferred to the air via the narrow channel the waterjet cuts in the ground. Currently the ground vibrations are detected with Doppler radar and video camera sensing, while the air vibrations are detected with a directional microphone. Data is collected via a Labview based data acquisition system. This data is then manipulated in Labview to produce the associated power spectrums. These power spectra are fed through various signal processing and recognition routines to determine the probability of there being an object present under the current test location and what that object is likely to be. Our current test area consists of a large X-Y positioning system placed over approximately a five-foot circular test area. The positioning system moves both the waterjet and the sensor package to the test location specified by the Labview control software. Currently we are able to locate buried land mine models at a distance of approximately three inches with a high degree of accuracy.

  6. Multi-point measurement of the acoustic particle velocity using a novel laser measurement method; Mehrpunktmessungen der Schallschnelle mittels neuartigem Lasermessverfahren

    Energy Technology Data Exchange (ETDEWEB)

    Haufe, Daniel; Schluessler, Raimund; Fischer, Andreas; Buettner, Lars; Czarske, Juergen [Technische Univ. Dresden (Germany). Professur fuer Mess- und Prueftechnik

    2012-07-01

    Reducing aircraft noise requires the analysis of the complex interaction between flow and sound phenomena in jet engine dampers. Therefore a Doppler global velocimeter with laser frequency modulation is used for the first time for the multi-point measurement of the acoustic particle velocity in a Kundt's tube. As a result, particle velocity amplitudes within the hearing range have been resolved, the minimal measurement uncertainty amounts to 3 mm/s at a measurement period of 1 s. The measurement technique has high potential in respect of analyzing and optimizing jet engine dampers. (orig.)

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

    Science.gov (United States)

    Wagner, C.R.; Mueller, D.S.

    2011-01-01

    A negative bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) can be caused by the movement of sediment on or near the streambed. The integration of a global positioning system (GPS) to track the movement of the ADCP can be used to avoid the systematic negative bias associated with a moving streambed. More than 500 discharge transects from 63 discharge measurements with GPS data were collected at sites throughout the US, Canada, and New Zealand with no moving bed to compare GPS and bottom-track-referenced discharges. Although the data indicated some statistical bias depending on site conditions and type of GPS data used, these biases were typically about 0.5% or less. An assessment of differential correction sources was limited by a lack of data collected in a range of different correction sources and different GPS receivers at the same sites. Despite this limitation, the data indicate that the use of Wide Area Augmentation System (WAAS) corrected positional data is acceptable for discharge measurements using GGA as the boat-velocity reference. The discharge data based on GPS-referenced boat velocities from the VTG data string, which does not require differential correction, were comparable to the discharges based on GPS-referenced boat velocities from the differentially-corrected GGA data string. Spatial variability of measure discharges referenced to GGA, VTG and bottom-tracking is higher near the channel banks. The spatial variability of VTG-referenced discharges is correlated with the spatial distribution of maximum Horizontal Dilution of Precision (HDOP) values and the spatial variability of GGA-referenced discharges is correlated with proximity to channel banks. ?? 2011 Published by Elsevier B.V.

  8. Continuous measurements of suspended sediment loads using dual frequency acoustic Doppler profile signals

    Science.gov (United States)

    Antonini, Alessandro; Guerrero, Massimo; Rüther, Nils; Stokseth, Siri

    2016-04-01

    A huge thread to Hydropower plants (HPP) is incoming sediments in suspension from the rivers upstream. The sediments settle in the reservoir and reduce the effective head as well as the volume and reduce consequently the lifetime of the reservoir. In addition are the fine sediments causing severe damages to turbines and infrastructure of a HPP. For estimating the amount of in-coming sediments in suspension and the consequent planning of efficient counter measures, it is essential to monitor the rivers within the catchment of the HPP for suspended sediments. This work is considerably time consuming and requires highly educated personnel and is therefore expensive. Surrogate-indirect methods using acoustic and optic devices have bee developed since the last decades that may be efficiently applied for the continuous monitoring of suspended sediment loads. The presented study proposes therefore to establish a research station at a cross section of a river which is the main tributary to a reservoir of a HPP and equip this station with surrogate as well as with common method of measuring suspended load concentrations and related flow discharge and level. The logger at the research station delivers data automatically to a server. Therefore it is ensured that also large flood events are covered. Data during flood are of high interest to the HPP planners since they carried the most part of the sediment load in a hydrological year. Theses peaks can hardly be measured with common measurement methods. Preliminary results of the wet season 2015/2016 are presented. The data gives insight in the applicable range, in terms of scattering particles concentration-average size and corresponding flow discharge and level, eventually enabling the study of suspended sediment load-water flow correlations during peak events. This work is carried out as part of a larger research project on sustainable hydro power plants exposed to high sediment yield, SediPASS. SediPASS is funded by the

  9. Observation of wind forced circulation on the continental shelf off Point Sur, California from a self-contained acoustic doppler current profiler.

    OpenAIRE

    Abbott, Christopher Lynn

    1991-01-01

    Approved for public release; distribution is unlimited To study the current structure of the California Current as it manifests itself on the continental shelf a subsurface mooring, P1, was anchored 5km west of Point Sur at 36(o), 17' N, 121(o), 59' W from 28 February through 11 May 1990. the P1 mooring, placed on the 84 m isobaths, consisted of a self-contained acoustic Doppler current profiler (SC-ADCP) housed in a syntactic foam sphere and secured to an anchor. The mooring geometry pl...

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

    Science.gov (United States)

    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.

  11. Correcting acoustic Doppler current profiler discharge measurement bias from moving-bed conditions without global positioning during the 2004 Glen Canyon Dam controlled flood on the Colorado River

    Science.gov (United States)

    Gartner, J.W.; Ganju, N.K.

    2007-01-01

    Discharge measurements were made by acoustic Doppler current profiler at two locations on the Colorado River during the 2004 controlled flood from Glen Canyon Dam, Arizona. Measurement hardware and software have constantly improved from the 1980s such that discharge measurements by acoustic profiling instruments are now routinely made over a wide range of hydrologic conditions. However, measurements made with instruments deployed from moving boats require reliable boat velocity data for accurate measurements of discharge. This is normally accomplished by using special acoustic bottom track pings that sense instrument motion over bottom. While this method is suitable for most conditions, high current flows that produce downstream bed sediment movement create a condition known as moving bed that will bias velocities and discharge to lower than actual values. When this situation exists, one solution is to determine boat velocity with satellite positioning information. Another solution is to use a lower frequency instrument. Discharge measurements made during the 2004 Glen Canyon controlled flood were subject to moving-bed conditions and frequent loss of bottom track. Due to site conditions and equipment availability, the measurements were conducted without benefit of external positioning information or lower frequency instruments. This paper documents and evaluates several techniques used to correct the resulting underestimated discharge measurements. One technique produces discharge values in good agreement with estimates from numerical model and measured hydrographs during the flood. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

  12. Laser speckle velocimeter for a robotized vehicle

    Science.gov (United States)

    Aliverdiev, A. A.; Caponero, M. A.; Moriconi, C.; Fichera, P. A.; Sagratella, G.

    2008-03-01

    The paper points out the progress in the exploitation of high, fast and precise non-contact velocimetry for robot applications. A technique for the precise measurement of the speed between two sliding surfaces has been developed during the research project for the realisation of an autonomous robot. The robot is devoted to the scouting of dangerous sites and to the execution of measurements in these places for the exploration of an extreme Antarctica environment (RAS project). This technique is based on the precise calculation of the common movement of a laser speckle field. This approach allows the realisation of a velocimeter suitable for use in extreme conditions. A description of the adopted methodology and the obtained results are the main topic of our work.

  13. The diel vertical migration of sound scatterers observed by an acoustic Doppler current profiler in the Luzon Strait from July 2009 to April 2011

    Institute of Scientific and Technical Information of China (English)

    YANG Chenghao; LIAO Guanghong; YUAN Yaochu; CHEN Hong; ZHU Xiaohua

    2013-01-01

    Acoustic Doppler current profiler (ADCP) receives echoes from sound scatterers, then their speed is calcu-lated by the Doppler effect. In the open ocean, most of these backscatterers are from the plankton. The sound scatterers descend down to depth at around dawn, their mean speed is 2.9 cm/s, then they ascend up to the surface layer at around dusk with a mean speed of 2.1 cm/s, in the Luzon Strait. The descending speed is faster, which suggests that this zooplankton population may accelerate its downward migration under the action of the gravity. The vertical distribution of a mean volume backscattering strength (MVB-S) in the nighttime has two peaks, which locate near the upper and lower boundary layers of halocline, respectively. However, the backscatterers only aggregate near the surface layer in the daytime. The diel ver-tical migration (DVM) of sound scatterers has several characteristic patterns, it is stronger in summer, but weaker in winter, and the maximum peak occurs in September. The DVM occurrence is synchronous with the seawater temperature increasing at around dawn and dusk, it may affect the ocean mixing and water stratification.

  14. Patterns of distribution of sound-scattering zooplankton in warm- and cold-core eddies in the Gulf of Mexico, from a narrowband acoustic Doppler current profiler survey

    Science.gov (United States)

    Zimmerman, Robert A.; Biggs, Douglas C.

    1999-03-01

    The acoustic backscatter intensity (ABI) reflected from epipelagic zooplankton communities in the central Gulf of Mexico was measured during June 1995 with a vessel-mounted, narrowband-153-kHz acoustic Doppler current profiler (ADCP). Horizontal and vertical variations in ABI were documented in three kinds of mesoscale hydrographic features commonly found in the Gulf of Mexico: the warm-core Loop Current (LC), a warm-core Loop Current eddy (LCE), and a cold-core region that separated the two warm-core features. Since new nitrogen domes close to surface waters in cold-core features whereas surface waters of warm-core features are nutrient depleted, the cold-core region was expected to have higher biological stocks as a result of locally higher primary production. Both ABI and net tow data confirmed that the cold-core region was in fact a zone of local aggregation of zooplankton and micronekton. During both day and night, ABI when integrated for the upper 50 and 100 m in the cold-core region was significantly greater than in the LC or in the LCE, and ABI was positively correlated with standing stock biomass taken by the net tows. Further investigations into the biological differences between Gulf of Mexico divergence and convergence regimes are warranted, and the ADCP will be a useful tool for examination of the distribution of sound scatterers in such features.

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

    Science.gov (United States)

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

    1988-01-01

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

  16. First results from Acoustic Doppler Current Profiler measurements of meltwater flux in a large supraglacial river in western Greenland compared with downstream proglacial river outflow

    Science.gov (United States)

    Pitcher, L. H.; Smith, L. C.; Overstreet, B. T.; Chu, V. W.; Rennermalm, A. K.; Cooper, M. G.; Gleason, C. J.; Yang, K.

    2015-12-01

    A vast network of seasonally evolving, thermally eroding supraglacial rivers on the southwestern Greenland Ice Sheet (GrIS) is the preeminent transporter of meltwater across this area of the ablation zone. Supraglacial rivers are important for estimating surface water storage and transport into moulins and into the en-, sub-, and proglacial environments. Yet, little is known about their role in the GrIS cryo-hydrologic system. To that end, supraglacial river discharge in a large river, the "Rio Behar" (67.05°, -49.02°; ~75 km from the Kangerlussuaq International Airport), was measured in situ over 300 times: approximately four times per hour over three consecutive days from July 19 - 22, 2015. The Rio Behar drains a ~ 70 km2 ice catchment and enters a large moulin in the Watson River land-ice watershed in western Greenland. River discharge was measured using a Sontek M9 Acoustic Doppler Current Profiler. Each profile records water temperature, depth-integrated velocity, channel width and channel bathymetry. This novel dataset can be used to assess diurnal variations in river discharge, slope, velocity, stream power, and channel incision in order to enhance process-level understanding of GrIS meltwater routing, storage and transport. Future work will compare supraglacial river discharge in the Rio Behar with in situ estimates of proglacial river outflow upstream of the Watson River bridge in Kangerlussuaq, Greenland.

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

    DEFF Research Database (Denmark)

    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...

  18. Morphology and flow fields of three-dimensional dunes, Rio Paraná, Argentina: Results from simultaneous multibeam echo sounding and acoustic Doppler current profiling

    Science.gov (United States)

    Parsons, D. R.; Best, J. L.; Orfeo, O.; Hardy, R. J.; Kostaschuk, R.; Lane, S. N.

    2005-12-01

    Most past studies of river dune dynamics have concentrated on two-dimensional (2-D) bed forms, with constant heights and straight crest lines transverse to the flow, and their associated turbulent flow structure. This morphological simplification imposes inherent limitations on the interpretation and understanding of dune form and flow dynamics in natural channels, where dune form is predominantly three-dimensional. For example, studies over 2-D forms neglect the significant influence that lateral flows and secondary circulation may have on the flow structure and thus dune morphology. This paper details a field study of a swath of 3-D dunes in the Rio Paraná, Argentina. A large (0.35 km wide, 1.2 km long) area of dunes was surveyed using a multibeam echo sounder (MBES) that provided high-resolution 3-D detail of the river bed. Simultaneous with the MBES survey, 3-D flow information was obtained with an acoustic Doppler current profiler (ADCP), revealing a complicated pattern of dune morphology and associated flow structure within the swath. Dune three-dimensionality appears intimately connected to the morphology of the upstream dune, with changes in crest line curvature and crest line bifurcations/junctions significantly influencing the downstream dune form. Dunes with lobe or saddle-shaped crest lines were found to have larger, more structured regions of vertical velocity with smaller separation zones than more 2-D straight-crested dunes. These results represent the first integrated study of 3-D dune form and mean flow structure from the field and show several similarities to recent laboratory models of flow over 3-D dunes.

  19. Evaluation of Acoustic Doppler Current Profiler to Measure Discharge at New York Power Authority's Niagara Power Project, Niagara Falls, New York

    Science.gov (United States)

    Zajd, Henry J.

    2007-01-01

    The need for accurate real-time discharge in the International Niagara River hydro power system requires reliable, accurate and reproducible data. The U.S. Geological Survey has been widely using Acoustic Doppler Current Profilers (ADCP) to accurately measure discharge in riverine channels since the mid-1990s. The use of the ADCP to measure discharge has remained largely untested at hydroelectric-generation facilities such as the New York Power Authority's (NYPA) Niagara Power Project in Niagara Falls, N.Y. This facility has a large, engineered diversion channel with the capacity of high volume discharges in excess of 100,000 cubic feet per second (ft3/s). Facilities such as this could benefit from the use of an ADCP, if the ADCP discharge measurements prove to be more time effective and accurate than those obtained from the flow-calculation techniques that are currently used. Measurements of diversion flow by an ADCP in the 'Pant Leg' diversion channel at the Niagara Power Project were made on November 6, 7, and 8, 2006, and compared favorably (within 1 percent) with those obtained concurrently by a conventional Price-AA current-meter measurement during one of the ADCP measurement sessions. The mean discharge recorded during each 2-hour individual ADCP measurement session compared favorably with (3.5 to 6.8 percent greater than) the discharge values computed by the flow-calculation method presently in use by NYPA. The use of ADCP technology to measure discharge could ultimately permit increased power-generation efficiency at the NYPA Niagara Falls Power Project by providing improved predictions of the amount of water (and thus the power output) available.

  20. Using Principal Component and Tidal Analysis as a Quality Metric for Detecting Systematic Heading Uncertainty in Long-Term Acoustic Doppler Current Profiler Data

    Science.gov (United States)

    Morley, M. G.; Mihaly, S. F.; Dewey, R. K.; Jeffries, M. A.

    2015-12-01

    Ocean Networks Canada (ONC) operates the NEPTUNE and VENUS cabled ocean observatories to collect data on physical, chemical, biological, and geological ocean conditions over multi-year time periods. Researchers can download real-time and historical data from a large variety of instruments to study complex earth and ocean processes from their home laboratories. Ensuring that the users are receiving the most accurate data is a high priority at ONC, requiring quality assurance and quality control (QAQC) procedures to be developed for all data types. While some data types have relatively straightforward QAQC tests, such as scalar data range limits that are based on expected observed values or measurement limits of the instrument, for other data types the QAQC tests are more comprehensive. Long time series of ocean currents from Acoustic Doppler Current Profilers (ADCP), stitched together from multiple deployments over many years is one such data type where systematic data biases are more difficult to identify and correct. Data specialists at ONC are working to quantify systematic compass heading uncertainty in long-term ADCP records at each of the major study sites using the internal compass, remotely operated vehicle bearings, and more analytical tools such as principal component analysis (PCA) to estimate the optimal instrument alignments. In addition to using PCA, some work has been done to estimate the main components of the current at each site using tidal harmonic analysis. This paper describes the key challenges and presents preliminary PCA and tidal analysis approaches used by ONC to improve long-term observatory current measurements.

  1. Study on Doppler Effects Estimate in Underwater Acoustic Communication Based on Fractional Fourier Transform%基于分数阶Fourier变换的水声通信多普勒系数估计技术研究

    Institute of Scientific and Technical Information of China (English)

    霍雁明; 刘媛; 张晓

    2012-01-01

    An estimate method of the Doppler effects in mobile underwater acoustic communication based on fractional Fourier transform has been proposed.The Doppler coefficients are obtained by estimating chirp rate change of LFM signal with fractional Fourier transform(FRFT) in this paper.And the performance of the Doppler effects estimation method based on FRFT is verified by the computer simulation.%本文基于传统多普勒系数估计方法,提出一种基于分数阶Fourier变换的多普勒系数估计方法,该方法利用分数阶Fourier变换估计得到经过信道后LFM信号调频斜率的变化量值,进而得到多普勒系数的估计。通过计算机仿真研究验证了该方法的有效性与稳健性。

  2. Doppler electron velocimetry : notes on creating a practical tool.

    Energy Technology Data Exchange (ETDEWEB)

    Reu, Phillip L.; Milster, Tom (University of Arizona)

    2008-11-01

    The Doppler electron velocimeter (DEV) has been shown to be theoretically possible. This report attempts to answer the next logical question: Is it a practical instrument? The answer hinges upon whether enough electrons are available to create a time-varying Doppler current to be measured by a detector with enough sensitivity and bandwidth. The answer to both of these questions is a qualified yes. A target Doppler frequency of 1 MHz was set as a minimum rate of interest. At this target a theoretical beam current signal-to-noise ratio of 25-to-1 is shown for existing electron holography equipment. A detector is also demonstrated with a bandwidth of 1-MHz at a current of 10 pA. Additionally, a Linnik-type interferometer that would increase the available beam current is shown that would offer a more flexible arrangement for Doppler electron measurements over the traditional biprism.

  3. Application of acoustic Doppler current profiler ADCP in hydrologic survey%声学多普勒流速剖面仪ADCP及其在水文测流中的应用

    Institute of Scientific and Technical Information of China (English)

    蓝标; 曲娟

    2011-01-01

    This paper describes flow measurement principle of ADCP (Acoustic Doppler Current Profiler).Compared with the regular hydrometric propeller,the characteristics and measurement process for ADCP flow measurement are introduced.The possible emerging problems in flow measurement of ADCP are summarized,and some attention matters are pointed out.%本文阐述了声学多普勒流速剖面仪ADCP的流量测量原理,并通过对ADCP流量测量仪与常规流速仪的比较,说明了ADCP流量测量的特点及其测量过程,并对ADCP流量测量中可能出现的问题进行了总结归纳,指出了应用中应注意的问题。

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

    OpenAIRE

    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 ...

  5. Measurement and Analysis of Coherent Flow Structures over Sand Dunes in the Missouri River near St. Louis, MO, by means of an Acoustic Doppler Current Profiler and a Multibeam Echo Sounder

    Science.gov (United States)

    Boldt, J.; Oberg, K. A.; Best, J. L.; Parsons, D. R.

    2011-12-01

    The topology, magnitude, and sediment transport capabilities of large-scale turbulence generated over alluvial sand dunes is influential in creating and maintaining dune morphology and in dominating both the flow field and the transport of suspended sediment above dune-covered beds. Combined measurements by means of an acoustic Doppler current profiler (ADCP) and a multibeam echo sounder (MBES) were made in order to examine flow over a series of sand dunes in the Missouri River, near St. Louis, MO, USA in October 2007. The bed topography of the Missouri River was mapped using a RESON 7125 MBES immediately before the ADCP data collection. Time series of velocity and acoustic backscatter were measured using a down-looking 1200 kHz ADCP while anchored at two locations in the dune field. The ADCP used in this study has a sampling rate of 2-3 Hz with 20-25 cm bin sizes. Two time series were collected having durations of 712 and 589 seconds at one location, while the third time series, collected about 4 meters upstream, was 2,270 seconds in duration. Measured streamwise velocities ranged from 0.1 to 2.7 ms-1 for all three stationary time series. Sediment concentration profiles were obtained at the same two locations as the stationary ADCP data using a P-61 sediment sampler and were compared to ADCP acoustic backscatter. Characteristics of turbulent flow structures in a sand bed river are presented. This paper presents data that can be used to investigate the issue of obtaining reliable estimates of turbulence parameters with an ADCP. The analyses will include mean velocity profiles, turbulence intensities, Reynolds shear stresses, quadrant analysis, power spectra, cross-correlation, and frequency analysis. Semi-periodic patterns were observed in each time series, characterized by periods of elevated acoustic backscatter with positive vertical velocities, followed by reduced acoustic backscatter with negative vertical velocities. The utility and limitations of combined

  6. Laser velocimeter data acquisition, processing, and control system

    International Nuclear Information System (INIS)

    The use of a mini-computer for data acquisition, processing, and control of a two-velocity-component dual beam laser velocimeter in a low-speed wind tunnel is described in detail. Digital stepping motors were programmed to map the mean-flow and turbulent fluctuating velocities in the test section boundary layer and free stream. The mini-computer interface controlled the operation of the LV processor and the high-speed selection of the photomultiplier tube whose output was to be processed. A statistical analysis of the large amount of data from the LV processor was performed by the computer while the experiment was in progress. The resulting velocities are in good agreement with hot-wire survey data obtained in the same facility

  7. 14- by 22-Foot Subsonic Tunnel Laser Velocimeter Upgrade

    Science.gov (United States)

    Meyers, James F.; Lee, Joseph W.; Cavone, Angelo A.; Fletcher, Mark T.

    2012-01-01

    A long-focal length laser velocimeter constructed in the early 1980's was upgraded using current technology to improve usability, reliability and future serviceability. The original, free-space optics were replaced with a state-of-the-art fiber-optic subsystem which allowed most of the optics, including the laser, to be remote from the harsh tunnel environment. General purpose high-speed digitizers were incorporated in a standard modular data acquisition system, along with custom signal processing software executed on a desktop computer, served as the replacement for the signal processors. The resulting system increased optical sensitivity with real-time signal/data processing that produced measurement precisions exceeding those of the original system. Monte Carlo simulations, along with laboratory and wind tunnel investigations were used to determine system characteristics and measurement precision.

  8. Modificações da hemodinâmica fetal pelo estímulo sonoro: avaliação pela dopplervelocimetria colorida Vibro-acoustic stimulation induced hemodynamic fetal changes assessed by color doppler

    Directory of Open Access Journals (Sweden)

    Francisco Mauad Filho

    1999-04-01

    Full Text Available Objetivos: verificar se ocorrem ou não alterações hemodinâmicas na aréria cerebral média (ACM aferido pela dopplervelocimetria colorida após realização de um estímulo sonoro. Métodos: trinta fetos de gestantes consideradas clinicamente normais com idade gestacional igual ou superior a 28 semanas foram submetidos a um estímulo sonoro. Examinamos as alterações da velocidade sangüínea na ACM fetal por meio do índice de resistência e da freqüência cardíaca fetal, pelo doppler colorido, antes e depois do estímulo acústico. Resultados: a média da freqüência cardíaca fetal (FCF antes do estímulo sonoro foi de 142,41 batimentos por minuto (bpm com desvio padrão de 9,01 e faixa de variação de 122 a 162 bpm. Após o estímulo sonoro, a média da FCF foi de 159,44 bpm com desvio padrão de 15,49, com faixa de variação de 130 a 187 bpm (pPurpose: to determine the possible occurrence of hemodynamic changes in the middle cerebral artery of the fetus (MCA using color doppler after vibro-acoustic stimulation. Methods: thirty fetuses from pregnant women considered to be clinically normal, with a gestational age of 28 weeks or more were submitted to vibro-acoustic stimulation. We examined the changes in blood flow rate in the middle cerebral artery of the fetus on the basis of resistance index (RI and fetal heart rate (FHR by color doppler before and after the sound stimulus. Results: mean FHR before vibro-acoustic stimulation was 142.41 beats per minute (bpm with a standard deviation of 9.01 and a range of 122 to 162 bpm. After stimulation, mean FHR was 159.44 bpm with a standard deviation of 15.49 and a range of 130 to 187 bpm (p<0.01. Mean RI in the MCA of the fetuses was 75.89% (range: 64 to 91% before the experiment. After the vibro-acoustic stimulation, mean RI was 66.93% (range: 47 to 83%; p < 0.01. Conclusions: we observed that a sound stimulus provokes the well-known immediate and significant elevation of FHR and a

  9. Acoustic and Laser Doppler Anemometer Results for Confluent, 22-Lobed, and Unique-Lobed Mixer Exhaust Systems for Subsonic Jet Noise Reduction

    Science.gov (United States)

    Salikuddin, M.; Martens, S.; Shin, H.; Majjigi, R. K.; Krejsa, Gene (Technical Monitor)

    2002-01-01

    The objective of this task was to develop a design methodology and noise reduction concepts for high bypass exhaust systems which could be applied to both existing production and new advanced engine designs. Special emphasis was given to engine cycles with bypass ratios in the range of 4:1 to 7:1, where jet mixing noise was a primary noise source at full power takeoff conditions. The goal of this effort was to develop the design methodology for mixed-flow exhaust systems and other novel noise reduction concepts that would yield 3 EPNdB noise reduction relative to 1992 baseline technology. Two multi-lobed mixers, a 22-lobed axisymmetric and a 21-lobed with a unique lobe, were designed. These mixers along with a confluent mixer were tested with several fan nozzles of different lengths with and without acoustic treatment in GEAE's Cell 41 under the current subtask (Subtask C). In addition to the acoustic and LDA tests for the model mixer exhaust systems, a semi-empirical noise prediction method for mixer exhaust system is developed. Effort was also made to implement flowfield data for noise prediction by utilizing MGB code. In general, this study established an aero and acoustic diagnostic database to calibrate and refine current aero and acoustic prediction tools.

  10. Range-instantaneous Doppler imaging of inverse synthetic aperture sonar

    Institute of Scientific and Technical Information of China (English)

    XU Jia; JIANG Xingzhou; TANG Jingsong

    2003-01-01

    Because the existing range-Doppler algorithm in inverse synthetic aperture sonar (ISAS) is based on target model of uniform motion, it may be invalidated for maneuvering targets due to the time-varying changes of both individual scatter′s Doppler and imaging projection plane. To resolve the problem, a new range-instantaneous Doppler imaging method is proposed for imaging maneuvering targets based on time-frequency analysis. The proposed approach is verified using real underwater acoustic data.

  11. Limitations on the use of laser velocimeter signals for particle sizing

    Science.gov (United States)

    Orloff, K. L.; Myer, F. C.; Mikasa, M. F.; Phillips, J. R.

    1976-01-01

    The paper discusses the complex relationship existing between the diameter of a particle, its index of refraction, and the output signal of a fringe-type laser velocimeter, and describes a special purpose laser velocimeter for aerosol sizing that determines aerosol size distributions on the basis of Farmer's (1973) relationship between visibility and particle size. In experiments with particles of known size, this relationship is in qualitative agreement with the experimentally observed results, the main differences being that (1) the visibility does not assume a minimum value of zero, as predicted, and (2) the visibility value above which there is no ambiguity in the corresponding fringe spacing is higher than that predicted.

  12. Retroreflector for photonic Doppler velocimetry

    Science.gov (United States)

    Lagoski, Thomas J.; Coutu, Ronald A., Jr.; Starman, LaVern A.

    2009-08-01

    In order to meet the goals of the Department of Defense (DoD) for smaller and more accurate weapons, numerous projects are currently investigating the miniaturization of weapons and munition fuze components. One of these efforts is to characterize the performance of small detonators. The velocity of the flyer, the key component needed to initiate a detonation sequence, can be measured using a photonic Doppler velocimeter (PDV). The purpose of this research was to develop a microelectromechanical system (MEMS) device that would act as an optimal retroreflective surface for the PDV. Two MEMS solutions were explored: one using the PolyMUMPsTM fabrication process and one in-house fabrication design using silicon on insulator (SOI) wafers. The in-house design consisted of an array of corner reflectors created using an SOI wafer. Each corner reflector consisted of three separate mirror plates which were self-assembled by photoresist pad hinges. When heated to a critical temperature (typically 140-160 °C), the photoresist pads melted and the resulting surface tension caused each mirror to rotate into place. The resulting array of corner reflectors was then coated with a thin layer of gold to increase reflectivity. Despite the successful assembly of a PolyMUMPsTM corner reflector, assembling an array of these reflectors was found to be unfeasible. Although the SOI corner reflector design was completed, these devices were not fabricated in time for testing during this research. However, the bidirectional reflectance distribution function (BRDF) and optical cross section (OCS) of commercially available retroreflective tapes were measured. These results can be used as a baseline comparison for future testing of a fabricated SOI corner reflector array.

  13. Laboratory Calibration of X-ray Velocimeters for Radiation Driven Winds and Outflows Surrounding X-ray Binaries and Active Galactic Nuclei

    Science.gov (United States)

    Brown, Gregory V.; Beiersdorfer, P.; Graf, A.; Hell, N.; Liedahl, D.; Magee, E. W.; Träbert, E.; Beilmann, C.; Bernitt, S.; Crespo-Lopez-Urritiua, J.; Eberle, S.; Kubicek, K.; Mäckel, V.; Rudolph, J.; Steinbrügge, R.; Ullrich, J.; Kelley, R. L.; Kilbourne, C. A.; Leutenegger, M.; Porter, F. S.; Rasmussen, A.; Simon, M.; Epp, S.

    2011-09-01

    High resolution measurements of X-ray absorption and fluorescence by radiation driven winds and outflows surrounding X-ray binaries and AGN provide a powerful means for measuring wind velocities. The accuracy of these X-ray velocimeters is limited by the accuracy of atomic data. For example, in the case of the high mass X-ray binary Vela X-1 the uncertainty in the calculated transition wavelengths of the K alpha lines produced by photoionization and photoexcitation of Si L-shell ions is comparable to the likely Doppler shifts, making it impossible to determine a reliable velocity. Similar problems also exist in the case of absorption of X-rays by M-shell Fe ions, which produces in some AGN the so-called unresolved transition array across the 15-17 angstrom band. In this case, there is a 15-45 milliangstrom variation among different wavelength calculations. The uncertainty in the calculations makes it impossible to reliably determine the true velocity structure of the outflow, and in turn, prevents a reliable determination of the mass-loss rate of the AGN. We present results of a recent series of laboratory experiments conducted using an electron beam ion trap coupled with the LCLS X-ray free electron laser and the BESSY-II synchrotron and designed to calibrate the velocimeters provided by high resolution instruments on Chandra and XMM-Newton. We also present results of resonant photoexcitation measurements of the transition wavelength of an Fe XVI satellite line 'coincident' with the 2p-3d Fe XVII line 3D at 15.26 angstroms. This line has never been resolved using emission spectroscopy and its measurement confirms the intensity of line 3D is sensitive to the relative abundance of Fe XVI and XVII and thus temperature. Work at LLNL was performed under the auspices of DOE under contract DE-AC53-07NA27344 and supported by NASA's APRA program.

  14. Design and implementation of embedded acoustic Doppler current profiler system based on OMAP platform%OMAP平台嵌入式声学多普勒流速剖面仪系统设计与实现

    Institute of Scientific and Technical Information of China (English)

    石靖鹏; 彭东立; 朱安珏

    2014-01-01

    The embedded Acoustic Doppler Current Profiler (ADCP) system has been developed on the basis of TI OMAP-L137 dual-core platform, and the measurement precision and performance are verified by experiments. Building complex echo signal first through intermediate frequency quadrature sampling, and then deriving water velocities by detecting the frequency shifts with complex correlation algorithm, and the principle of the algorithm is studied in the paper. The DSP core of OMAP is mainly responsible for echo processing, system design including system control, data communication, signal processing, etc. Combining the simulation tests, precision and performance of the equipment are verified by underwater experiment in Qian Dao Lake. Good results of flow measurement and stability of system are obtained, and the desired design index is achieved, which has a certain reference value for the development of the em-bedded platform sonar equipment.%在TI公司OMAP-L137双核平台的基础上,对嵌入式声学多普勒测流系统进行设计和实现,并通过实验对系统测流精度和性能进行验证。先通过中频正交采样构建回波复包络信号,再采用复相关算法检测信号的频移进行流速测量。在文中对算法进行了研究和原理分析。OMAP中的DSP核主要负责回波处理,系统设计包括系统控制、数据通信、信号处理等。结合仿真测试,并通过某湖水下实验对设备进行了精度和性能验证,获得了良好的测流效果并且系统具有很好的稳定性,达到了预期的设计指标。对于嵌入式平台水声设备的研制有一定的参考价值。

  15. Extending the turbidity record: making additional use of continuous data from turbidity, acoustic-Doppler, and laser diffraction instruments and suspended-sediment samples in the Colorado River in Grand Canyon

    Science.gov (United States)

    Voichick, Nicholas; Topping, David J.

    2014-01-01

    Turbidity is a measure of the scattering and absorption of light in water, which in rivers is primarily caused by particles, usually sediment, suspended in the water. Turbidity varies significantly with differences in the design of the instrument measuring turbidity, a point that is illustrated in this study by side-by-side comparisons of two different models of instruments. Turbidity also varies with changes in the physical parameters of the particles in the water, such as concentration, grain size, grain shape, and color. A turbidity instrument that is commonly used for continuous monitoring of rivers has a light source in the near-infrared range (860±30 nanometers) and a detector oriented 90 degrees from the incident light path. This type of optical turbidity instrument has a limited measurement range (depending on pathlength) that is unable to capture the high turbidity levels of rivers that carry high suspended-sediment loads. The Colorado River in Grand Canyon is one such river, in which approximately 60 percent of the range in suspended-sediment concentration during the study period had unmeasurable turbidity using this type of optical instrument. Although some optical turbidimeters using backscatter or other techniques can measure higher concentrations of suspended sediment than the models used in this study, the maximum turbidity measurable using these other turbidimeters may still be exceeded in conditions of especially high concentrations of suspended silt and clay. In Grand Canyon, the existing optical turbidity instruments remain in use in part to provide consistency over time as new techniques are investigated. As a result, during these periods of high suspended-sediment concentration, turbidity values that could not be measured with the optical turbidity instruments were instead estimated from concurrent acoustic attenuation data collected using side-looking acoustic-Doppler profiler (ADP) instruments. Extending the turbidity record to the full

  16. Laser velocimeter data acquisition system for the Langley 14- by 22-foot subsonic tunnel. Software reference guide version 3.3

    Science.gov (United States)

    Jumper, Judith K.

    1994-01-01

    The Laser Velocimeter Data Acquisition System (LVDAS) in the Langley 14- by 22-Foot Tunnel is controlled by a comprehensive software package. The software package was designed to control the data acquisition process during wind tunnel tests which employ a laser velocimeter measurement system. This report provides detailed explanations on how to configure and operate the LVDAS system to acquire laser velocimeter and static wind tunnel data.

  17. Laser velocimeter measurements of multiphase flow of solids

    Energy Technology Data Exchange (ETDEWEB)

    Kadambi, J.R.; Chen, R.C.; Bhunia, S.

    1989-01-01

    A unique refractive index matched facility for studying solid-liquid multiphase flow has been developed. The refractive index matching of the solid and the liquid allows the use of non-intrusive Laser Doppler Velocimetry (LDV) to measure the solid and the liquid velocities. These measurements will be useful in developing a better understanding of solid-liquid flows, especially solid-liquid and solid-solid interactions. Silica gel and 50% sodium iodide solution in water (refractive index {approx}1.443) are used as the refractive index matched solid and liquid respectively. A two color back scatter mode LDV is used for making velocity measurements. Tests were conducted in solid-liquid slurries with volumetric solid concentration levels of 5% and 15% in the Reynolds number (Re) range of 400 to 9200. Silica gel particles of mean diameter 40 microns were used. Measurements included mapping of the solid and liquid velocities and obtaining the pressure drop data. Signal processing technique utilizing histogram of velocity measurements made at a point and signal amplitude discrimination was successfully used for differentiating between solid and liquid velocities. 34 refs., 61 figs., 5 tabs.

  18. Superharmonic microbubble Doppler effect in ultrasound therapy

    Science.gov (United States)

    Pouliopoulos, Antonios N.; Choi, James J.

    2016-08-01

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  104-5  ×  107 microbubbles ml-1) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75-366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s-1, prior to the onset of

  19. Superharmonic microbubble Doppler effect in ultrasound therapy

    Science.gov (United States)

    Pouliopoulos, Antonios N.; Choi, James J.

    2016-08-01

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  104–5  ×  107 microbubbles ml‑1) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75–366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s‑1, prior to the onset

  20. Ocean Current Velocity Moored Time-Series Records collected from moored Acoustic Doppler Current Profilers near Grammanik Bank Spawning Aggregation Site (SPAG) and Frenchcap Cay, United States Virgin Islands, from April 24, 2011 to September 25, 2011 (NODC Accession 0088064)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Nortek 600kHz Aquadopp acoustic current profilers were deployed between April 2011 and September 2011 on shallow water moorings located on the coastal shelf south...

  1. Ocean Current Velocity Moored Time-Series Records, collected from moored Acoustic Doppler Current Profilers (ADCP) during 2010 and 2011 in Vieques Sound and Virgin Passage (NODC Accession 0088063)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Nortek 600kHz Aquadopp acoustic current profilers were deployed between March 2010 and April 2011 on shallow water moorings located in Vieques Sound, Puerto Rico,...

  2. Ocean Current Velocity Moored Time-Series Records, collected from moored Acoustic Doppler Current Profilers (ADCP) during 2011 near Grammanik Bank SPAG and Frenchcap Cay, USVI (NODC Accession 0088064)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Nortek 600kHz Aquadopp acoustic current profilers were deployed between April 2011 and September 2011 on shallow water moorings located on the coastal shelf south...

  3. Complex Doppler effect in left-handed metamaterials

    CERN Document Server

    Ziemkiewicz, David

    2014-01-01

    The Doppler shift is investigated in one-dimensional system with moving source. Theoretical findings are confirmed in numerical simulations of optical and acoustical waves propagation in simple metamaterial model, showing the reversed shift and the existence of multiple frequency modes. The properties of these waves are discussed. The effect of absorption on the phenomenon is outlined.

  4. Differential doppler heterodyning technique

    DEFF Research Database (Denmark)

    Lading, Lars

    1971-01-01

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

  5. Ultrasonic colour Doppler imaging

    DEFF Research Database (Denmark)

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

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue ...

  6. OFDM for Underwater Acoustic Communication

    OpenAIRE

    Thottappilly, Arjun

    2011-01-01

    Communicating wirelessly underwater has been an area of interest for researchers, engineers, and practitioners alike. One of the main reasons for the slow rate of progress in this area is that the underwater acoustic channel is in general much more hostile â in terms of multipath, frequency selectivity, noise, and the Doppler effect â than the over-the-air radio frequency channel. In this work a time warp based technique which can be used to model time-varying wideband Doppler shifts (as ...

  7. The Estimation and Compensation of Doppler Effect on Underwater Acoustic Spread Spectrum Communication%水声扩频通信中多普勒估计与补偿算法研究

    Institute of Scientific and Technical Information of China (English)

    袁兆凯; 隋天宇; 李宇; 黄海宁

    2012-01-01

    The Doppler effect is inherent in communication systems which makes the carrier synchronization critical to the whole system. In underwater communication environment, the Doppler effect is more severe due to the limited sound speed. In this paper, the Doppler effect of underwater channel is analyzed by formulas on a software-defined radio communication system. Then an effective algorithm is developed which can estimate and compensate the frequency shift. The simulation results show that this algorithm works out within the speed of 15 m/s, when the signal to noise ratio is above -22 dB. The sea experimental results show that the system can successfully achieve the carry wave synchronization with the speed to be 6 knots.%通信系统普遍受多普勒效应影响,因而载波同步成为通信中的一项关键技术.在水声通信中,由于声速有限,信道中的多普勒效应的影响更为明显.该文在一个基于软件无线电机制的水声扩频通信系统中,对水声信道的多普勒效应进行分析和建模,并在此基础上提出了一种有效的水声扩频多普勒估计与补偿算法.仿真实验表明,算法能够在-22 dB的情况下有效地对15 m/s以内产生的多普勒频移进行估计与补偿.算法经过海试测试,在6节速度及加速减速过程中,系统均能够成功地完成载波同步.

  8. Development of a New, Precise Near-infrared Doppler Wavelength Reference: A Fiber Fabry-Perot Interferometer

    CERN Document Server

    Halverson, Samuel; Ramsey, Lawrence; Redman, Stephen; Nave, Gillian; Wilson, John C; Hearty, Fred; Holtzman, Jon

    2012-01-01

    We present the ongoing development of a commercially available Micron Optics fiber-Fabry Perot Interferometer as a precise, stable, easy to use, and economic spectrograph reference with the goal of achieving <1 m/s long term stability. Fiber Fabry-Perot interferometers (FFP) create interference patterns by combining light traversing different delay paths. The interference creates a rich spectrum of narrow emission lines, ideal for use as a precise Doppler reference. This fully photonic reference could easily be installed in existing NIR spectrographs, turning high resolution fiber-fed spectrographs into precise Doppler velocimeters. First light results on the Sloan Digital Sky Survey III (SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectrograph and several tests of major support instruments are also presented. These instruments include a SuperK Photonics fiber supercontinuum laser source and precise temperature controller. A high resolution spectrum obtained using the NIST 2-m...

  9. Characteristics Analysis of HFM Signal over Underwater Acoustic Channels

    Directory of Open Access Journals (Sweden)

    YUAN Fei

    2013-01-01

    Full Text Available For pulse compression characteristics and not easily affected by noise, linear frequency modulation signal are widely used in underwater acoustic communication. This paper analyzes the characteristics of hyperbolic frequency modulation signal over underwater acoustic channels. Compared with linear frequency modulation signal, hyperbolic frequency modulation has the same performance of strong anti-noise and anti-multipath, what’s more, hyperbolic frequency modulation signal is better resist the influence of doppler. And discussed the influence of doppler on signal, simulation results show that the hyperbolic frequency modulation signal detection rate is better than linear frequency modulation signal in the doppler environment.

  10. Direction sensitive laser velocimeter. [determining the direction of particles using a helium-neon laser

    Science.gov (United States)

    Franke, J. M. (Inventor)

    1981-01-01

    A laser velocimeter is described which determines the direction of movement of particles. A laser produces a transmitted beam that illuminates the volume under investigation. The backscattered light is divided into two equal intensity beams. A first part of a sample of the transmitted beam is mixed with one of the two equal intensity beams and applied to a first photodetector. A second part of the sample is phase shifted by 90 deg, mixed with the other of the two equal intensity beams and applied to a second photodetector. The output of the first photodetector is phase shifted by 90 deg and then multiplied with the output of the second photodetector to produce a signal indicative of direction of movement.

  11. Shock loading characteristics of Zr and Ti metals using dual beam velocimeter

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, A. K., E-mail: a-saxena@barc.gov.in; Kaushik, T. C.; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2015-08-21

    The characteristics of titanium and zirconium metal foils under shock loading have been studied up to 16 GPa and 12 GPa pressure, respectively, using portable electric gun setup as projectile launcher. In these experiments, the capabilities of a single Fabry-Perot velocimeter have been enhanced by implementing it in dual beam mode to record the two velocity profiles on a single streak camera. The measured equation of state data for both the metals have been found to be well in agreement with the reported Hugoniot, within experimental accuracies. A phase transition from α to ω phase has been detected near to 11.4 GPa for titanium and 8.2 GPa for zirconium in the rising part of target-glass interface velocity profile.

  12. Development of microprocessor-based laser velocimeter and its application to measurement of jet exhausts and flows over missiles at high angles of attack

    Science.gov (United States)

    Harwell, K. E.; Farmer, W. M.; Hornkohl, J. O.; Stallings, E.

    1981-03-01

    During the past three years, personnel have developed a unique three-component laser velocimeter for the in situ measurement of particle and/or gas velocities in flow fields produced behind bodies at high angles of attack and in jet exhaust plumes. This report describes the development of the laser velocimeter and its subsequent application of the measurement of the velocity distribution and vortex structure in free jets and in flows over missiles at high angles of attack.

  13. Communication Acoustics

    DEFF Research Database (Denmark)

    Blauert, Jens

    Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

  14. Acoustic Neuroma

    Science.gov (United States)

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  15. Ultrasonic Doppler Modes

    Science.gov (United States)

    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.

  16. Planar Velocity Distribution of Viscous Debris Flow at Jiangjia Ravine, Yunnan, China: A Field Measurement Using Two Radar Velocimeters

    Institute of Scientific and Technical Information of China (English)

    FU Xudong; WANG Guangqian; KANG Zhicheng; FEI Xiangjun

    2007-01-01

    Characteristics of planar velocity distribution of viscous debris flow were analyzed using the measured data at Jiangjia Ravine, Yunnan, China. The velocity data were measured through using two radar velocimeters. The cross-sectional mean velocities were calculated and used to examine Kang et al's (2004) relationship, which was established for converting the flow velocity at river centerline measured by a radar velocimeter into the mean velocity based on the stop-watch method. The velocity coefficient, K, defined by the ratio of the mean velocity to the maximum velocity, ranges from 0.2 to 0.6. Kang et al's (2004) relationship was found being inapplicable to flows with K smaller than 0.43. This paper contributes to show the complexity of the planar velocity distribution of viscous debris flows and the applicability of Kang et al's relationship.

  17. Acoustic Doppler current profiling from the JGOFS Arabian Sea cruises aboard the RV T.G. THOMPSON: TN043, January 8, 1995--February 4, 1995; TN044, February 8, 1995--February 25, 1995; TN045, March 14, 1995--April 10, 1995; TN046, April 14, 1995--April 29, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Flagg, C.N.; Kim, H.S.; Shi, Y.

    1995-09-01

    Acoustic Doppler current profiler (ADCP) data from the R/V T.G. THOMPSON is part of the core data for the US JGOFS Arabian Sea project along with hydrographic and nutrient data. Seventeen cruises on the THOMPSON are scheduled to take place between September 1994 and January 1996. This is the second in a series of data reports covering the ADCP data from the Arabian Sea JGOFS cruises TNO43 through TNO46. ADCP data are being collected on all the JGOFS Arabian Sea cruises using an autonomous data acquisition system developed for ship-of-opportunity cruises. This system, referred to as the AutoADCP, makes it possible to collect the ADCP data without the constant monitoring usually necessary and assures constant data coverage and uniform data quality. This data report presents ADCP results from the second group of four JGOFS cruises, TNO43 through TNO46, concentrating on the data collection and processing methods. The ADCP data itself reside in a CODAS data base at Brookhaven National Laboratory and is generally available to JGOFS investigators through contact with the authors. The CODAS data base and associated ADCP processing software were developed over a number of years by Eric Firing and his group at the University of Hawaii. The CODAS software is shareware available for PC`s or Unix computers and is the single most widely used ADCP processing program for ship mounted units.

  18. Doppler cooling a microsphere

    CERN Document Server

    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.

  19. Impeller flow field characterization with a laser two-focus velocimeter

    Science.gov (United States)

    Brozowski, L. A.; Ferguson, T. V.; Rojas, L.

    1993-01-01

    Use of Computational Fluid Dynamics (CFD) codes, prevalent in the rocket engine turbomachinery industry, necessitates data of sufficient quality and quantity to benchmark computational codes. Existing data bases for typical rocket engine configurations, in particular impellers, are limited. In addition, traditional data acquisition methods have several limitations: typically transducer uncertainties are 0.5% of transducer full scale and traditional pressure probes are unable to provide flow characteristics in the circumferential (blade-to-blade) direction. Laser velocimetry circumvents these limitations by providing +0.5% uncertainty in flow velocity and +0.5% uncertainty in flow angle. The percent of uncertainty in flow velocity is based on the measured value, not full range capability. The laser electronics multiple partitioning capability allows data acquired between blades as the impeller rotates, to be analyzed separately, thus providing blade-to-blade flow characterization. Unlike some probes, the non-intrusive measurements made with the laser velocimeter does not disturb the flow. To this end,, and under Contract (NAS8-38864) to the National Aeronautics and Space Administration (NASA) at Marshall Space Flight Center (MSFC), an extensive test program was undertaken at Rocketdyne. Impellers from two different generic rocket engine pump configurations were examined. The impellers represent different spectrums of pump design: the Space Shuttle Main Engine (SSME) high pressure fuel turbopump (HPFTP) impeller was designed in the 1 1970's the Consortium for CFD application in Propulsion Technology Pump Stage Technology Team (Pump Consortium) optimized impeller was designed with the aid of modern computing techniques. The tester configuration for each of the impellers consisted of an axial inlet, an inducer, a diffuser, and a crossover discharge. While the tested configurations were carefully chosen to be representative of generic rocket engine pumps, several

  20. Pulse Doppler radar

    CERN Document Server

    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

  1. Doppler Cooling a Microsphere

    OpenAIRE

    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...

  2. Laser Doppler measurement of relative blood velocity in the human optic nerve head.

    Science.gov (United States)

    Riva, C E; Grunwald, J E; Sinclair, S H

    1982-02-01

    The Doppler shift frequency spectrum (DSFS) of laser light scattered from red blood cells (RBCs) moving in the microcirculation of the optic nerve head has been recorded in normal volunteers by means of a fundus camera laser Doppler velocimeter. The width of the DSFS, which varies in proportion to the speed of the RBCs, has been characterized by a parameter alpha. With the use of a model for the scattering of light by tissue and RBCs and for the RBC velocity distribution, values of alpha recorded at normal intraocular pressure (IOP) suggest that the RBCs that contribute to the Doppler signal are flowing in capillaries. The parameter alpha was found to vary markedly with the IOP and with the phase of the ocular pressure pulse at elevated IOP. The return of the speed of RBCs toward normal, which is observed after a step increase of IOP above normal and after a step decrease below normal, has been attributed to an autoregulatory response of the optic nerve circulation.

  3. The Doppler Pendulum Experiment

    Science.gov (United States)

    Lee, C. K.; Wong, H. K.

    2011-01-01

    An experiment to verify the Doppler effect of sound waves is described. An ultrasonic source is mounted at the end of a simple pendulum. As the pendulum swings, the rapid change of frequency can be recorded by a stationary receiver using a simple frequency-to-voltage converter. The experimental results are in close agreement with the Doppler…

  4. Doppler-musical instrument

    International Nuclear Information System (INIS)

    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)

  5. Acoustical Imaging

    CERN Document Server

    Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging

    2012-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging

  6. Acoustic textiles

    CERN Document Server

    Nayak, Rajkishore

    2016-01-01

    This book highlights the manufacturing and applications of acoustic textiles in various industries. It also includes examples from different industries in which acoustic textiles can be used to absorb noise and help reduce the impact of noise at the workplace. Given the importance of noise reduction in the working environment in several industries, the book offers a valuable guide for companies, educators and researchers involved with acoustic materials.

  7. Laser Doppler flowmetry imaging

    Science.gov (United States)

    Nilsson, Gert E.; Wardell, Karin

    1994-02-01

    A laser Doppler perfusion imager has been developed that makes possible mapping of tissue blood flow over surfaces with extensions up to about 12 cm X 12 cm. The He-Ne laser beam scans the tissue under study throughout 4096 measurement sites. A fraction of the backscattered and Doppler broadened light is detected by a photo diode positioned about 20 cm above the tissue surface. After processing, a signal that scales linearly with perfusion is stored in a computer and a color coded image of the spatial tissue perfusion is shown on a monitor. A full format scan is completed in about 4.5 minutes. Algorithms for calculating perfusion profiles and averages as well as substraction of one image from another, form an integral part of the system data analysis software. The perfusion images can also be exported to other software packages for further processing and analysis.

  8. Laser Doppler imaging, revisited

    OpenAIRE

    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.

  9. HF Doppler observations

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Quantitative Laser Doppler Flowmetry

    OpenAIRE

    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...

  11. Laser double Doppler flowmeter

    Science.gov (United States)

    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.

  12. Radiation acoustics

    CERN Document Server

    Lyamshev, Leonid M

    2004-01-01

    Radiation acoustics is a developing field lying at the intersection of acoustics, high-energy physics, nuclear physics, and condensed matter physics. Radiation Acoustics is among the first books to address this promising field of study, and the first to collect all of the most significant results achieved since research in this area began in earnest in the 1970s.The book begins by reviewing the data on elementary particles, absorption of penetrating radiation in a substance, and the mechanisms of acoustic radiation excitation. The next seven chapters present a theoretical treatment of thermoradiation sound generation in condensed media under the action of modulated penetrating radiation and radiation pulses. The author explores particular features of the acoustic fields of moving thermoradiation sound sources, sound excitation by single high-energy particles, and the efficiency and optimal conditions of thermoradiation sound generation. Experimental results follow the theoretical discussions, and these clearl...

  13. Laser doppler perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Laser doppler perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Laser doppler perfusion imaging

    International Nuclear Information System (INIS)

    Recording of tissue perfusion is important in assessing the influence of peripheral vascular diseases on the microcirculation. This thesis reports on a laser doppler perfusion imager based on dynamic light scattering in tissue. When a low power He-Ne laser beam sequentally scans the tissue, moving blood cells generate doppler components in the back-scattered light. A fraction of this light is detected by a photodetector and converted into an electrical signal. In the processor, a signal proportional to the tissue perfusion at each measurement site is calculated and stored. When the scanning procedure is completed, a color-coded perfusion image is presented on a monitor. To convert important aspects of the perfusion image into more quantitative parameters, data analysis functions are implemented in the software. A theory describing the dependence of the distance between individual measurement points and detector on the system amplification factor is proposed and correction algorithms are presented. The performance of the laser doppler perfusion imager was evaluated using a flow simulator. A linear relationship between processor output signal and flow through the simulator was demonstrated for blood cell concentrations below 0.2%. The median sampling depth of the laser beam was simulated by a Monte Carlo technique and estimated to 235 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

  16. Cooperative OFDM underwater acoustic communications

    CERN Document Server

    Cheng, Xilin; Cheng, Xiang

    2016-01-01

    Following underwater acoustic channel modeling, this book investigates the relationship between coherence time and transmission distances. It considers the power allocation issues of two typical transmission scenarios, namely short-range transmission and medium-long range transmission. For the former scenario, an adaptive system is developed based on instantaneous channel state information. The primary focus is on cooperative dual-hop orthogonal frequency division multiplexing (OFDM). This book includes the decomposed fountain codes designed to enable reliable communications with higher energy efficiency. It covers the Doppler Effect, which improves packet transmission reliability for effective low-complexity mirror-mapping-based intercarrier interference cancellation schemes capable of suppressing the intercarrier interference power level. Designed for professionals and researchers in the field of underwater acoustic communications, this book is also suitable for advanced-level students in electrical enginee...

  17. Comparisons between PW Doppler system and enhanced FM Doppler system

    DEFF Research Database (Denmark)

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

    1995-01-01

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

  18. Room Acoustics

    Science.gov (United States)

    Kuttruff, Heinrich; Mommertz, Eckard

    The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

  19. Acoustical Imaging

    CERN Document Server

    Akiyama, Iwaki

    2009-01-01

    The 29th International Symposium on Acoustical Imaging was held in Shonan Village, Kanagawa, Japan, April 15-18, 2007. This interdisciplinary Symposium has been taking place every two years since 1968 and forms a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. In the course of the years the volumes in the Acoustical Imaging Series have developed and become well-known and appreciated reference works. Offering both a broad perspective on the state-of-the-art in the field as well as an in-depth look at its leading edge research, this Volume 29 in the Series contains again an excellent collection of seventy papers presented in nine major categories: Strain Imaging Biological and Medical Applications Acoustic Microscopy Non-Destructive Evaluation and Industrial Applications Components and Systems Geophysics and Underwater Imaging Physics and Mathematics Medical Image Analysis FDTD method and Other Numerical Simulations Audience Researcher...

  20. Battlefield acoustics

    CERN Document Server

    Damarla, Thyagaraju

    2015-01-01

    This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code...

  1. Acoustics Research

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B....

  2. ANL Doppler flowmeter

    Science.gov (United States)

    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.

  3. Doppler Beats or Interference Fringes?

    Science.gov (United States)

    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;…

  4. Holographic imaging of surface acoustic waves

    CERN Document Server

    Bruno, Francois; Royer, Daniel; Atlan, Michael

    2014-01-01

    We report on an experimental demonstration of surface acoustic waves monitoring on a thin metal plate with heterodyne optical holography. Narrowband imaging of local optical pathlength modulation is achieved with a frequency-tunable time-averaged laser Doppler holographic imaging scheme on a sensor array, at video-rate. This method enables robust and quantitative mapping of out-of-plane vibrations of nanometric amplitudes at radiofrequencies.

  5. Acoustic biosensors.

    Science.gov (United States)

    Fogel, Ronen; Limson, Janice; Seshia, Ashwin A

    2016-06-30

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  6. How to study the Doppler effect with Audacity software

    Science.gov (United States)

    Adriano Dias, Marco; Simeão Carvalho, Paulo; Rodrigues Ventura, Daniel

    2016-05-01

    The Doppler effect is one of the recurring themes in college and high school classes. In order to contextualize the topic and engage the students in their own learning process, we propose a simple and easily accessible activity, i.e. the analysis of the videos available on the internet by the students. The sound of the engine of the vehicle passing by the camera is recorded on the video; it is then analyzed with the free software Audacity by measuring the frequency of the sound during approach and recede of the vehicle from the observer. The speed of the vehicle is determined due to the application of Doppler effect equations for acoustic waves.

  7. Acoustic Doppler current profile (ADCP) data from FRD cruises

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is an archive of raw data obtained from the ADCP for cruises conducted by the SWFSC Fisheries Resources Division from 1991 to present.

  8. ALOHA Cabled Observatory (ACO): Acoustic Doppler Current Profiler (ADCP): Velocity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The University of Hawaii's ALOHA ("A Long-term Oligotrophic Habitat Assessment") Cabled Observatory (ACO) is located 100 km north of the island of Oahu, Hawaii (22...

  9. ALOHA Cabled Observatory (ACO): Acoustic Doppler Current Profiler (ADCP): Temperature

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The University of Hawaii's ALOHA ("A Long-term Oligotrophic Habitat Assessment") Cabled Observatory (ACO) is located 100 km north of the island of Oahu, Hawaii (22...

  10. Acoustic emission

    International Nuclear Information System (INIS)

    This paper is related to our activities on acoustic emission (A.E.). The work is made with different materials: metals and fibre reinforced plastics. At present, acoustic emission transducers are being developed for low and high temperature. A test to detect electrical discharges in electrical transformers was performed. Our experience in industrial tests to detect cracks or failures in tanks or tubes is also described. The use of A.E. for leak detection is considered. Works on pattern recognition of A.E. signals are also being performed. (Author)

  11. Combined perfusion and doppler imaging using plane-wave nonlinear detection and microbubble contrast agents.

    Science.gov (United States)

    Tremblay-Darveau, Charles; Williams, Ross; Milot, Laurent; Bruce, Matthew; Burns, Peter N

    2014-12-01

    Plane-wave imaging offers image acquisition rates at the pulse repetition frequency, effectively increasing the imaging frame rates by up to two orders of magnitude over conventional line-by-line imaging. This form of acquisition can be used to achieve very long ensemble lengths in nonlinear modes such as pulse inversion Doppler, which enables new imaging trade-offs that were previously unattainable. We first demonstrate in this paper that the coherence of microbubble signals under repeated exposure to acoustic pulses of low mechanical index can be as high as 204 ± 5 pulses, which is long enough to allow an accurate power Doppler measurement. We then show that external factors, such as tissue acceleration, restrict the detection of perfusion at the capillary level with linear Doppler, even if long Doppler ensembles are considered. Hence, perfusion at the capillary level can only be detected with ultrasound through combined microbubbles and Doppler imaging. Finally, plane-wave contrast-enhanced power and color Doppler are performed on a rabbit kidney in vivo as a proof of principle. We establish that long pulse-inversion Doppler sequences and conventional wall-filters can create an image that simultaneously resolves both the vascular morphology of veins and arteries, and perfusion at the capillary level with frame rates above 100 Hz.

  12. Doppler effect in a solid medium: Spin wave emission by a precessing domain wall drifting in spin current

    Science.gov (United States)

    Xia, Hong; Chen, Jie; Zeng, Xiaoyan; Yan, Ming

    2016-04-01

    The Doppler effect is a fundamental physical phenomenon observed for waves propagating in vacuum or various media, commonly gaseous or liquid. Here, we report on the occurrence of a Doppler effect in a solid medium. Instead of a real object, a topological soliton, i.e., a magnetic domain wall (DW) traveling in a current-carrying ferromagnetic nanowire, plays the role of the moving wave source. The Larmor precession of the DW in an external field stimulates emission of monochromatic spin waves (SWs) during its motion, which show a significant Doppler effect, comparable to the acoustic one of a train whistle. This process involves two prominent spin-transfer-torque effects simultaneously, the current-driven DW motion and the current-induced SW Doppler shift. The latter gives rise to an interesting feature, i.e., the observed SW Doppler effect appears resulting from a stationary source and a moving observer, contrary to the laboratory frame.

  13. SPIRou: the near-infrared spectropolarimeter/high-precision velocimeter for the Canada-France-Hawaii telescope

    CERN Document Server

    Artigau, Étienne; Donati, Jean-François; Doyon, René; Delfosse, Xavier; Baratchart, Sébastien; Lacombe, Marielle; Moutou, Claire; Rabou, Patrick; Parès, Laurent P; Micheau, Yoan; Thibault, Simon; Reshetov, Vladimir A; Dubois, Bruno; Hernandez, Olivier; Vallée, Philippe; Wang, Shiang-Yu; Dolon, François; Pepe, Francesco A; Bouchy, François; Striebig, Nicolas; Hénault, François; Loop, David; Saddlemyer, Leslie; Barrick, Gregory; Vermeulen, Tom; Dupieux, Michel; Hébrard, Guillaume; Boisse, Isabelle; Martioli, Eder; Alencar, Silvia H P; Nascimento, José-Diaz do; Figueira, Pedro

    2014-01-01

    SPIRou is a near-IR \\'echelle spectropolarimeter and high-precision velocimeter under construction as a next-generation instrument for the Canada-France-Hawaii-Telescope. It is designed to cover a very wide simultaneous near-IR spectral range (0.98-2.35 {\\mu}m) at a resolving power of 73.5K, providing unpolarized and polarized spectra of low-mass stars at a radial velocity (RV) precision of 1m/s. The main science goals of SPIRou are the detection of habitable super-Earths around low-mass stars and the study of how critically magnetic fields impact star / planet formation. Following a successful final design review in Spring 2014, SPIRou is now under construction and is scheduled to see first light in late 2017. We present an overview of key aspects of SPIRou's optical and mechanical design.

  14. Development of the Seeding System Used for Laser Velocimeter Surveys of the NASA Low-Speed Centrifugal Compressor Flow Field

    Science.gov (United States)

    Wasserbauer, C. A.; Hathaway, M. D.

    1994-01-01

    Consideration is given to an atomizer-based system for distributing high-volume rates of polystyrene latex (PSL) seed material developed to support laser velocimeter investigations of the NASA Low-Speed Compressor flow field. Complete evaporation of the liquid carrier before the flow entering the compressor was of primary concern for the seeder system design. It is argued that the seed nozzle should incorporate a needle valve that can mechanically dislodge accumulated PSL seed material when the nozzle is turned off. Water is less expensive as the liquid carrier and should be used whenever adequate residence times are available to ensure complete evaporation. PSL agglomerates over time and needs to be mixed or blended before use. Arrangement of the spray nozzles needs to be adjustable to provide maximum seeding at the laser probe volume.

  15. Wind climatology observed over Kalpakkam using Doppler sodar

    International Nuclear Information System (INIS)

    Acoustic remote sensing of the prevailing winds in the boundary layer finds an important application in studying the problems related to air pollution meteorology. Analysis of the seasonal variation of vertical and horizontal wind speed with altitude is made using the Doppler sodar data collected at an atomic research centre, Kalpakkam. A pictorial representation of horizontal wind flow for each season is given in the form of wind roses at three lower levels of probing, namely 100, 300 and 500 m. Such analysis would prove to be a basic reference material for taking necessary meaningful emergency measures in similar climatic regions. (author). 18 refs., 10 figs

  16. High Resolution Doppler Lidar

    Science.gov (United States)

    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.

  17. Acoustic estimation of suspended sediment concentration

    Institute of Scientific and Technical Information of China (English)

    ZHU; Weiqing(

    2001-01-01

    [1]Morse, P. H. , Theoretical Acoustics, New York: McGraw-Hill Book Co. , 1968.[2]Skudrjuk, E., Die Grundlagen der Akustik, Wien: Springer-Verlag, 1954.[3]Olshevskii, V. V., Statistical Characteristics of Sea Reverberation, Moscow: Nauka Publisher, 1966.[4]Thorne, P. D., Hardcastl, P. J., Soulsby, R. L., Analysis of acoustic measurements of suspended sediments, J. Geop.Res. , 1993, 98: 899.[5]Guo Jijie, Ren Laifa, Li Yunwu, ln-situ calibration of acoustic measurement of suspended sedienmt, Acta Oceanologica Sini-ca, 1998, (20): 120-125.[6]Zhang Shuying, Li Yunwu, Development and application of an acoustic suspended sediemnt monitoring system, Acta Oceanologica Sinica, 1998, (20): 114-119.[7]Zhang Shuying, Li Yunwu, A theoretical analysis of acoustic suspended sediment obsvervation, Acta Acoustica, 1999, (24):267-274.[8]Zhu Weiqing, Pan Feng, Zhu Min et al. , IOA-1 Multi-function Acoustic Doppler Current Profiler (MADCP), OCEAN'2000,Rhode Island, USA.

  18. 基于声学仪器与粒径分析仪研究东海浮游动物昼夜垂直迁移过程%The diel vertical migration of zooplankton observed by an acoustic Doppler current profiler and particle size analyzer in the East China Sea

    Institute of Scientific and Technical Information of China (English)

    徐亚军; 赵亮; 原野

    2016-01-01

    The diel migration of zooplankton is closely related to the population fluctuation and feeding rhythm,and the study on the diel migration of zooplankton has become an important part of their community dynamics.In the present study,the diel vertical migration of zooplankton was studied by acoustic Doppler current profiler (ADCP) and laser particle analyzer (LISST-100)over 24 h off the coast of Zhejiang Province in summer 2013.The time series of backscatter coefficient (S v )calculated by ADCP echo intensity and particle size spectrum from LISST-100 are used to study the vertical migration of zooplankton and its characteristics.Euchaeta concinna showed a re-markable diurnal vertical migration with a mean vertical speed is about 0.05 m/s.It feed in the thermocline at night,and hide in the bottom Taiwan warm water at daytime.It can be found from particle size spectrum that the large particle aggregate,meanwhile particles with size of 100 -150 μm decrease in the thermocline at the night. The particle size of suspended particles has obvious diel rhythms in the water column,which indicate that there should be diurnal variation of biological community structure in different water level.%浮游动物的昼夜迁移活动与其种群变动和摄食节律紧密联系,浮游动物昼夜移动的研究已经成为种群动力学研究的一个重要组成部分。2013年夏季在浙江东部近海,结合声学多普勒流速剖面仪(ADCP)和激光粒径分析仪(LISST-100)等仪器进行了一次定点周日连续观测。通过声学反演方法,得到后向散射强度剖面的时间变化,结合 LISST-100得到的水体悬浮物粒径谱,研究了浮游动物垂直迁移及其习性。分析发现了可能是精致真刺水蚤的一次昼夜垂直迁移过程,其在夜间进入跃层附近进食,白天蛰伏于底层低温高盐的台湾暖流水中,垂向迁移速度达到了0.05 m/s。LISST-100观测还发现在夜间跃层边

  19. Use of a tethersonde measurement system to conduct a Doppler SODAR performance audit

    Energy Technology Data Exchange (ETDEWEB)

    Wilkerson, G.W. [North American Weather Consultants, Salt Lake City, UT (United States); Catizone, P.A. [TRC Environmental Corp., Windsor, CT (United States); Coble, T.D. [ASARCO Inc., East Helena, MT (United States)

    1994-12-31

    With the increased usage of dispersion models that require stack top wind information, such as the Complex Terrain Dispersion Model (CTDM), the need for a reliable method to collect elevated wind data has also increased. Doppler Sound Detection and Ranging (SODAR) instruments have gained recognition as a viable means of collecting such data. SODAR technology has improved greatly over the last decade and is now a cost effective alternative to tall meteorological towers. SODARs are remote sensing devices that sample the atmosphere and calculate wind speed and wind direction data at different altitudes. This is accomplished by measuring the doppler shift of an acoustic pulse emitted by a ground level antenna.

  20. Acoustic and optical variations during rapid downward motion episodes in the deep north-western Mediterranean Sea

    NARCIS (Netherlands)

    van Haren, H.; Taupier-Letage, I.; Aguilar, J.A.; Albert, A.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Jesus, A.C.A.; Astraatmadja, T.; Aubert, J.J.; Auer, R.; Baret, B.; Basa, S.; Bazzotti, M.; Bertin, V.; Biagi, S.; Bigongiari, C.; Bou-Cabo, M.; Bouwhuis, M.C.; Brown, A.; Brunner, J.; Busto, J.; Camarena, F.; Capone, A.; Carminati, G.; Carr, J.; Castel, D.; Castorina, E.; Cavasinni, V.; Cecchini, S.; Charvis, P.; Chiarusi, T.; Circella, M.; Coniglione, R.; Costantini, H.; Cottini, N.; Coyle, P.; Curtil, C.; De Bonis, G.; Decowski, M.P.; Dekeyser, I.; Deschamps, A.; Distefano, C.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; Emanuele, U.; Ernenwein, J.P.; Escoffier, S.; Fehr, F.; Flaminio, V.; Fratini, K.; Fritsch, U.; Fuda, J.L.; Giacomelli, G.; Gomez-Gonzalez, J.P.; Graf, K.; Guillard, G.; Halladjian, G.; Hallewell, G.; Heijboer, A.J.; Hello, Y.; Hernandez-Rey, J.J.; Hossl, J.; De Jong, M.; Kalantar-Nayestanaki, N.; Kalekin, O.; Kappes, A.; Katz, U.; Kooijman, P.; Kopper, C.; Kouchner, A.; Kretschmer, W.; Lahmann, R.; Lamare, P.; Lambard, G.; Larosa, G.; Laschinsky, H.; Lefevre, D.; Lelaizant, G.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Lucarelli, F.; Lyons, K.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martinez-Mora, J.A.; Maurin, G.; Mazure, A.; Melissas, M.; Montaruli, T.; Morganti, M.; Moscoso, L.; Motz, H.; Naumann, C.; Neff, M.; Ostasch, R.; Palioselitis, G.; Pavalas, G.E.; Payre, P.; Petrovic, J.; Piattelli, P.; Picot-Clemente, N.; Picq, C.; Pillet, R.; Popa, V.; Pradier, T.; Presani, E.; Racca, C.; Radu, A.; Reed, C.; Riccobene, G.; Richardt, C.; Rujoiu, M.; Russo, G.V.; Salesa, F.; Schoeck, F.; Schuller, J.P.; Shanidze, R.; Simeone, F.; Spurio, M.; Steijger, J.J.M.; Stolarczyk, T.; Tamburini, C.; Tasca, L.; Toscano, S.; Vallage, B.; Van Elewyck, V.; Vecchi, M.; Vernin, P.; Wijnker, G.; de Wolf, E.; Yepes, H.; Zaborov, D.; Zornoza, J.D.; Zuniga, J.

    2011-01-01

    An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site of the ANTARES neutrino telescope near Toulon, France, thus providing a unique opportunity to compare high-resolution acoustic and optical observations between 70 and 170 m above the sea bed at 2475 m. The ADCP measured down

  1. General principles of carotid Doppler ultrasonography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Whal [Dept. of Radiology, Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2014-03-15

    Carotid Doppler ultrasonography is a popular tool for evaluating atherosclerosis of the carotid artery. Its two-dimensional gray scale can be used for measuring the intima-media thickness, which is very good biomarker for atherosclerosis and can aid in plaque characterization. The plaque morphology is related to the risk of stroke. The ulceration of plaque is also known as one of the strong predictors of future embolic event risk. Color Doppler ultrasonography and pulse Doppler ultrasonography have been used for detecting carotid artery stenosis. Doppler ultrasonography has unique physical properties. The operator should be familiar with the physics and other parameters of Doppler ultrasonography to perform optimal Doppler ultrasonography studies.

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

    Science.gov (United States)

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

    2015-01-01

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

  3. Doppler peaks from active perturbations

    CERN Document Server

    Magueijo, J; Coulson, D; Ferreira, P; Magueijo, Joao; Albrecht, Andreas; Coulson, David; Ferreira, Pedro

    1995-01-01

    We examine how the qualitative structure of the Doppler peaks in the angular power spectrum of the cosmic microwave anisotropy depends on the fundamental nature of the perturbations which produced them. The formalism of Hu and Sugiyama is extended to treat models with cosmic defects. We discuss how perturbations can be ``active'' or ``passive'' and ``incoherent'' or ``coherent'', and show how causality and scale invariance play rather different roles in these various cases. We find that the existence of secondary Doppler peaks and the rough placing of the primary peak unambiguously reflect these basic properties.

  4. Inverse Doppler Effects in Flute

    CERN Document Server

    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.

  5. Corrections to sodar Doppler winds due to wind drift

    Directory of Open Access Journals (Sweden)

    Stuart Bradley

    2015-11-01

    Full Text Available Refraction of the acoustic beam from a sodar, or translation of the beam due to the wind (known as wind drift, both affect the scattering angle and hence the Doppler shift of the return signal. Wind drift has been the subject of a number of previous studies, which have shown that errors increase with wind speed, giving about 6 % error in the estimated wind speed when the actual wind speed is 7 ms−1. Since previous studies have not treated the general case of finite angular beam width, a new analytic treatment is given here for monostatic sodars. Surprisingly, it is found that the Doppler error contributed by the transmitted beam is exactly compensated by the Doppler error contributed by the received beam, if the two beam widths are the same. If the transmitter beam width is not equal to the receiver beam width, then either over-estimation or under-estimation of wind speed results, depending on which beam is wider. This has implications for bi-static sodars, in which it is not possible to match beam widths. Contrary to this new theory, examples of field comparisons with mast instrumentation show a non-linear relationship between wind speeds measured by a sodar and wind speeds measured by mast-mounted instruments. It is proposed that this is due to the acoustic baffle clipping the received beam and changing its width, since the received beam must return at lower elevations from scattering downwind. This is shown to be feasible for a Metek sodar. The sign and magnitude of the observed non-linear dependence of estimated wind speed on actual wind speed are consistent with this proposed mechanism.

  6. Wayside Bearing Fault Diagnosis Based on a Data-Driven Doppler Effect Eliminator and Transient Model Analysis

    Directory of Open Access Journals (Sweden)

    Fang Liu

    2014-05-01

    Full Text Available A fault diagnosis strategy based on the wayside acoustic monitoring technique is investigated for locomotive bearing fault diagnosis. Inspired by the transient modeling analysis method based on correlation filtering analysis, a so-called Parametric-Mother-Doppler-Wavelet (PMDW is constructed with six parameters, including a center characteristic frequency and five kinematic model parameters. A Doppler effect eliminator containing a PMDW generator, a correlation filtering analysis module, and a signal resampler is invented to eliminate the Doppler effect embedded in the acoustic signal of the recorded bearing. Through the Doppler effect eliminator, the five kinematic model parameters can be identified based on the signal itself. Then, the signal resampler is applied to eliminate the Doppler effect using the identified parameters. With the ability to detect early bearing faults, the transient model analysis method is employed to detect localized bearing faults after the embedded Doppler effect is eliminated. The effectiveness of the proposed fault diagnosis strategy is verified via simulation studies and applications to diagnose locomotive roller bearing defects.

  7. Wayside bearing fault diagnosis based on a data-driven Doppler effect eliminator and transient model analysis.

    Science.gov (United States)

    Liu, Fang; Shen, Changqing; He, Qingbo; Zhang, Ao; Liu, Yongbin; Kong, Fanrang

    2014-05-05

    A fault diagnosis strategy based on the wayside acoustic monitoring technique is investigated for locomotive bearing fault diagnosis. Inspired by the transient modeling analysis method based on correlation filtering analysis, a so-called Parametric-Mother-Doppler-Wavelet (PMDW) is constructed with six parameters, including a center characteristic frequency and five kinematic model parameters. A Doppler effect eliminator containing a PMDW generator, a correlation filtering analysis module, and a signal resampler is invented to eliminate the Doppler effect embedded in the acoustic signal of the recorded bearing. Through the Doppler effect eliminator, the five kinematic model parameters can be identified based on the signal itself. Then, the signal resampler is applied to eliminate the Doppler effect using the identified parameters. With the ability to detect early bearing faults, the transient model analysis method is employed to detect localized bearing faults after the embedded Doppler effect is eliminated. The effectiveness of the proposed fault diagnosis strategy is verified via simulation studies and applications to diagnose locomotive roller bearing defects.

  8. Wayside bearing fault diagnosis based on a data-driven Doppler effect eliminator and transient model analysis.

    Science.gov (United States)

    Liu, Fang; Shen, Changqing; He, Qingbo; Zhang, Ao; Liu, Yongbin; Kong, Fanrang

    2014-01-01

    A fault diagnosis strategy based on the wayside acoustic monitoring technique is investigated for locomotive bearing fault diagnosis. Inspired by the transient modeling analysis method based on correlation filtering analysis, a so-called Parametric-Mother-Doppler-Wavelet (PMDW) is constructed with six parameters, including a center characteristic frequency and five kinematic model parameters. A Doppler effect eliminator containing a PMDW generator, a correlation filtering analysis module, and a signal resampler is invented to eliminate the Doppler effect embedded in the acoustic signal of the recorded bearing. Through the Doppler effect eliminator, the five kinematic model parameters can be identified based on the signal itself. Then, the signal resampler is applied to eliminate the Doppler effect using the identified parameters. With the ability to detect early bearing faults, the transient model analysis method is employed to detect localized bearing faults after the embedded Doppler effect is eliminated. The effectiveness of the proposed fault diagnosis strategy is verified via simulation studies and applications to diagnose locomotive roller bearing defects. PMID:24803197

  9. Doppler tomography in fusion plasmas and astrophysics

    CERN Document Server

    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 ...

  10. Numerical and experimental study of Lamb wave propagation in a two-dimensional acoustic black hole

    Science.gov (United States)

    Yan, Shiling; Lomonosov, Alexey M.; Shen, Zhonghua

    2016-06-01

    The propagation of laser-generated Lamb waves in a two-dimensional acoustic black-hole structure was studied numerically and experimentally. The geometrical acoustic theory has been applied to calculate the beam trajectories in the region of the acoustic black hole. The finite element method was also used to study the time evolution of propagating waves. An optical system based on the laser-Doppler vibration method was assembled. The effect of the focusing wave and the reduction in wave speed of the acoustic black hole has been validated.

  11. Boundary Layer Measurements in a Supersonic Wind Tunnel Using Doppler Global Velocimetry

    Science.gov (United States)

    Meyers, James F.; Lee, Joseph W.; Cavone, Angelo A.

    2010-01-01

    A modified Doppler Global Velocimeter (DGV) was developed to measure the velocity within the boundary layer above a flat plate in a supersonic flow. Classic laser velocimetry (LV) approaches could not be used since the model surface was composed of a glass-ceramic insulator in support of heat-transfer measurements. Since surface flare limited the use of external LV techniques and windows placed in the model would change the heat transfer characteristics of the flat plate, a novel approach was developed. The input laser beam was divided into nine equal power beams and each transmitted through optical fibers to a small cavity within the model. The beams were then directed through 1.6-mm diameter orifices to form a series of orthogonal beams emitted from the model and aligned with the tunnel centerline to approximate a laser light sheet. Scattered light from 0.1-micron diameter water condensation ice crystals was collected by four 5-mm diameter lenses and transmitted by their respective optical fiber bundles to terminate at the image plane of a standard two-camera DGV receiver. Flow measurements were made over a range from 0.5-mm above the surface to the freestream at Mach 3.51 in steady state and heat pulse injected flows. This technique provides a unique option for measuring boundary layers in supersonic flows where seeding the flow is problematic or where the experimental apparatus does not provide the optical access required by other techniques.

  12. Understanding Doppler Broadening of Gamma Rays

    Energy Technology Data Exchange (ETDEWEB)

    Rawool-Sullivan, Mohini [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sullivan, John P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-03

    Doppler-broadened gamma ray peaks are observed routinely in the collection and analysis of gamma-ray spectra. If not recognized and understood, the appearance of Doppler broadening can complicate the interpretation of a spectrum and the correct identification of the gamma ray-emitting material. We have conducted a study using a simulation code to demonstrate how Doppler broadening arises and provide a real-world example in which Doppler broadening is found. This report describes that study and its results.

  13. Photoacoustics meets ultrasound: micro-Doppler photoacoustic effect and detection by ultrasound

    CERN Document Server

    Gao, Fei; Zheng, Yuanjin; Ohl, Claus-Dieter

    2014-01-01

    In recent years, photoacoustics has attracted intensive research for both anatomical and functional biomedical imaging. However, the physical interaction between photoacoustic generated endogenous waves and an exogenous ultrasound wave is a largely unexplored area. Here, we report the initial results about the interaction of photoacoustic and external ultrasound waves leading to a micro-Doppler photoacoustic (mDPA) effect, which is experimentally observed and consistently modelled. It is based on a simultaneous excitation on the target with a pulsed laser and continuous wave (CW) ultrasound. The thermoelastically induced expansion will modulate the CW ultrasound and leads to transient Doppler frequency shift. The reported mDPA effect can be described as frequency modulation of the intense CW ultrasound carrier through photoacoustic vibrations. This technique may open the possibility to sensitively detect the photoacoustic vibration in deep optically and acoustically scattering medium, avoiding acoustic distor...

  14. Anomalous Doppler effects in bulk phononic crystal

    International Nuclear Information System (INIS)

    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.

  15. Micro-Doppler Analysis of Small UAVs

    NARCIS (Netherlands)

    Wit, J.J.M. de; Harmanny, R.I.A.; Prémel Cabic, G.

    2012-01-01

    Coherent radar measures micro-Doppler properties of moving objects. The micro-Doppler signature depends on parts of an object moving and rotating in addition to the main body motion (e.g. rotor blades) and is therefore characteristic for the type of object. In this study, the micro-Doppler signature

  16. Speckles in laser doppler perfusion imaging

    NARCIS (Netherlands)

    Rajan, Vinayakrishnan

    2007-01-01

    Laser Doppler Flowmetry (LDF) is a noninvasive diagnostic method to measure blood flow in tissue [1]. The technique is based on measuring the Doppler shift induced by moving red blood cells to the illuminating coherent light. A laser Doppler instrument often gives output signals related to the flux,

  17. The Doppler Effect--A New Approach

    Science.gov (United States)

    Allen, J.

    1973-01-01

    Discusses the Doppler effect as it applies to different situations, such as a stationary source of sound with the observer moving, a stationary observer, and the sound source and observer both moving. Police radar, satellite surveillance radar, radar astronomy, and the Doppler navigator, are discussed as applications of Doppler shift. (JR)

  18. Time-Height Variations of Ion-Line Doppler Spectra at HAARP

    Science.gov (United States)

    Watkins, B. J.; Fallen, C. T.

    2012-12-01

    O-mode HF heating results in enhanced electron temperatures in the lower ionosphere that in turn result in enhanced electron densities due to temperature-dependent molecular ion chemistry. As a result, for a fixed HF heating frequency, the altitude of the HF interaction region decreases with time after the onset of HF heating. Corresponding altitudes of the HF-enhanced ion-line signals detected with the MUIR UHF-frequency diagnostic radar also decrease with time. For the data presented here, the radar range resolution was 600 meters, and time-height Doppler spectra were obtained for every pulse (10ms inter-pulse period) of the UHF-radar. We have therefore been able to examine the height-dependent spectral characteristics of ion-line signals every 10ms. The UHF radar signals show a brief initial period after HF turn-on (about 120ms) when signals are scattered around zero Doppler over about 2km height range. The UHF signals then rapidly convert to a stable configuration with two ion-line signatures (approximately +/- 5kHz Doppler values); above a fixed height there is only positive Doppler data (downward ion-acoustic waves), and below that height there is only negative Doppler data (upward ion-acoustic waves). The power associated with the downward ion-acoustic waves is typically stronger than the upward waves. For the example shown, this spectral type persists for the entire duration of the HF heating time, at progressively lower heights. We suggest that the spectral characteristics are associated with HF frequencies near the 3rd gyro harmonic.

  19. A Doppler Transient Model Based on the Laplace Wavelet and Spectrum Correlation Assessment for Locomotive Bearing Fault Diagnosis

    Directory of Open Access Journals (Sweden)

    Changqing Shen

    2013-11-01

    Full Text Available The condition of locomotive bearings, which are essential components in trains, is crucial to train safety. The Doppler effect significantly distorts acoustic signals during high movement speeds, substantially increasing the difficulty of monitoring locomotive bearings online. In this study, a new Doppler transient model based on the acoustic theory and the Laplace wavelet is presented for the identification of fault-related impact intervals embedded in acoustic signals. An envelope spectrum correlation assessment is conducted between the transient model and the real fault signal in the frequency domain to optimize the model parameters. The proposed method can identify the parameters used for simulated transients (periods in simulated transients from acoustic signals. Thus, localized bearing faults can be detected successfully based on identified parameters, particularly period intervals. The performance of the proposed method is tested on a simulated signal suffering from the Doppler effect. Besides, the proposed method is used to analyze real acoustic signals of locomotive bearings with inner race and outer race faults, respectively. The results confirm that the periods between the transients, which represent locomotive bearing fault characteristics, can be detected successfully.

  20. World-leading science with SPIRou - the nIR spectropolarimeter / high-precision velocimeter for CFHT

    CERN Document Server

    Delfosse, X; Kouach, D; Hébrard, G; Doyon, R; Artigau, E; Bouchy, F; Boisse, I; Brun, A S; Hennebelle, P; Widemann, T; Bouvier, J; Bonfils, X; Morin, J; Moutou, C; Pepe, F; Udry, S; Nascimento, J -D do; Alencar, S H P; Castilho, B V; Martioli, E; Wang, S Y; Figueira, P; Santos, N C

    2013-01-01

    SPIRou is a near-infrared (nIR) spectropolarimeter / velocimeter proposed as a new-generation instrument for CFHT. SPIRou aims in particular at becoming world-leader on two forefront science topics, (i) the quest for habitable Earth-like planets around very- low-mass stars, and (ii) the study of low-mass star and planet formation in the presence of magnetic fields. In addition to these two main goals, SPIRou will be able to tackle many key programs, from weather patterns on brown dwarf to solar-system planet atmospheres, to dynamo processes in fully-convective bodies and planet habitability. The science programs that SPIRou proposes to tackle are forefront (identified as first priorities by most research agencies worldwide), ambitious (competitive and complementary with science programs carried out on much larger facilities, such as ALMA and JWST) and timely (ideally phased with complementary space missions like TESS and CHEOPS). SPIRou is designed to carry out its science mission with maximum efficiency and ...

  1. A three-dimensional orthogonal laser velocimeter for the NASA Ames 7- by 10-foot wind tunnel

    Science.gov (United States)

    Dunagan, Stephen E.; Cooper, Donald L.

    1995-01-01

    A three-component dual-beam laser-velocimeter system has been designed, fabricated, and implemented in the 7-by 10-Foot Wind Tunnel at NASA Ames Research Center. The instrument utilizes optical access from both sides and the top of the test section, and is configured for uncoupled orthogonal measurements of the three Cartesian coordinates of velocity. Bragg cell optics are used to provide fringe velocity bias. Modular system design provides great flexibility in the location of sending and receiving optics to adapt to specific experimental requirements. Near-focus Schmidt-Cassegrain optic modules may be positioned for collection of forward or backward scattered light over a large solid angle, and may be clustered to further increase collection solid angle. Multimode fiber optics transmit collected light to the photomultiplier tubes for processing. Counters are used to process the photomultiplier signals and transfer the processed data digitally via buffered interface controller to the host MS-DOS computer. Considerable data reduction and graphical display programming permit on-line control of data acquisition and evaluation of the incoming data. This paper describes this system in detail and presents sample data illustrating the system's capability.

  2. Flow near a model spur dike with a fixed scoured bed

    Science.gov (United States)

    Three-dimensional flow velocities were measured using an acoustic Doppler velocimeter at a closely spaced grid over a fixed scoured bed with a submerged spur dike. Three-dimensional flow velocities were measured at 3484 positions around the trapezoidal shaped submerged model spur dike over a fixed ...

  3. Sound Power Estimation by Laser Doppler Vibration Measurement Techniques

    Directory of Open Access Journals (Sweden)

    G.M. Revel

    1998-01-01

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

  4. Nonlinear characterization of a single-axis acoustic levitator

    Science.gov (United States)

    Andrade, Marco A. B.; Ramos, Tiago S.; Okina, Fábio T. A.; Adamowski, Julio C.

    2014-04-01

    The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jump phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed.

  5. Nonlinear characterization of a single-axis acoustic levitator

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marco A. B. [Institute of Physics, University of São Paulo, São Paulo (Brazil); Ramos, Tiago S.; Okina, Fábio T. A.; Adamowski, Julio C. [Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica, University of São Paulo, São Paulo (Brazil)

    2014-04-15

    The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jump phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed.

  6. Radio wave diffraction during the passage of an acoustic shock through a sporadic E layer

    International Nuclear Information System (INIS)

    Bistatic HF Doppler measurements of the ionospheric disturbance arising from a large ground-level chemical explosion have revealed a peculiar HF return which begins at large positive Doppler (greater than +5 Hz) and linearly evolves to large negative Doppler (less than -5 Hz). Various pieces of evidence in the data suggest that an HF wave which is diffracted from the intersection of the acoustic shock and an extensive plane of sporadic E ionization at 110 km was observed. From these measurements the horizontal trace velocity of the locus of intersection is estimated. 16 references

  7. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available Educational Video Home What is an AN What is an Acoustic Neuroma? Identifying an AN Symptoms Acoustic Neuroma Keywords Educational Video ... for pre- and post-treatment acoustic neuroma patients. Home What is an AN What is an Acoustic ...

  8. Acoustic cryocooler

    Science.gov (United States)

    Swift, Gregory W.; Martin, Richard A.; Radenbaugh, Ray

    1990-01-01

    An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintian a cooling load of 5 W at 80 K.

  9. Azimuthal Doppler Effect in Optical Vortex Spectroscopy

    Science.gov (United States)

    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.

  10. Acoustic telemetry.

    Energy Technology Data Exchange (ETDEWEB)

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

    Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

  11. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  12. Using microwave Doppler radar in automated manufacturing applications

    Science.gov (United States)

    Smith, Gregory C.

    Since the beginning of the Industrial Revolution, manufacturers worldwide have used automation to improve productivity, gain market share, and meet growing or changing consumer demand for manufactured products. To stimulate further industrial productivity, manufacturers need more advanced automation technologies: "smart" part handling systems, automated assembly machines, CNC machine tools, and industrial robots that use new sensor technologies, advanced control systems, and intelligent decision-making algorithms to "see," "hear," "feel," and "think" at the levels needed to handle complex manufacturing tasks without human intervention. The investigator's dissertation offers three methods that could help make "smart" CNC machine tools and industrial robots possible: (1) A method for detecting acoustic emission using a microwave Doppler radar detector, (2) A method for detecting tool wear on a CNC lathe using a Doppler radar detector, and (3) An online non-contact method for detecting industrial robot position errors using a microwave Doppler radar motion detector. The dissertation studies indicate that microwave Doppler radar could be quite useful in automated manufacturing applications. In particular, the methods developed may help solve two difficult problems that hinder further progress in automating manufacturing processes: (1) Automating metal-cutting operations on CNC machine tools by providing a reliable non-contact method for detecting tool wear, and (2) Fully automating robotic manufacturing tasks by providing a reliable low-cost non-contact method for detecting on-line position errors. In addition, the studies offer a general non-contact method for detecting acoustic emission that may be useful in many other manufacturing and non-manufacturing areas, as well (e.g., monitoring and nondestructively testing structures, materials, manufacturing processes, and devices). By advancing the state of the art in manufacturing automation, the studies may help

  13. Acoustic dispersive prism

    OpenAIRE

    Hussein Esfahlani; Sami Karkar; Herve Lissek; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic ...

  14. [Doppler echocardiography of ventricular diastole].

    Science.gov (United States)

    Roudaut, R; Gosse, P; Dallocchio, M

    1988-12-01

    Non-invasive studies of left ventricular relaxation and filling by means of doppler-echocardiography are of considerable interest owing to easy recording and good reproducibility. However, such physiological parameters as site of measurement, heart rate and, chiefly, age may interfere with the curves obtained. The interpretation of tracings must also take into account the presence of mitral valve pathology (stenosis or regurgitation), aortic stenosis, disorders of atrioventricular (prolonged PR complex) or intraventricular (left bundle branch block) conduction and medication (e.g. vasodilators). In clinical practice, one of the main advantages of the technique is that it makes it possible to distinguish between the physiological left ventricular hypertrophy (LVH) of top-class sportsmen (without impaired ventricular filling) and the pathological LVH of hypertrophic cardiomyopathy. The purpose of this study, with a review of the literature, was to take stock of the value and limitations of the doppler indices.

  15. Causality and the Doppler Peaks

    OpenAIRE

    Turok, Neil

    1996-01-01

    Could cosmic structure have formed by the action of causal physics within the standard hot big bang, or was a prior period of inflation required? Recently there has been some discussion of whether causal sources could reproduce the pattern of Doppler peaks of the standard scale-invariant adiabatic theory. This paper gives a rigorous definition of causality, and a causal decomposition of a general source. I present an example of a simple causal source which mimics the standard adiabatic theory...

  16. Frequency Diversity for OFDM Mobile Communication via Underwater Acoustic Channels

    Institute of Scientific and Technical Information of China (English)

    Gang Qiao; Wei Wang; Ran Guo; Rehan Khan; Yue Wang

    2012-01-01

    The major constraint on the performance of orthogonal frequency division multiplexing (OFDM) based underwater acoustic (UWA) communication is to keep subcarriers orthogonal.In this paper,Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange.In practice,for mobile communication,adjustment and tuning of transducers in order to get spatial diversity is extremely difficult.Considering the relatively low coherence bandwidth in UWA,the frequency diversity design with the Doppler compensation function was elaborated here.The outfield experiments of mobile underwater acoustic communication (UWAC) based on OFDM were carried out with 0.17 bit/(s.Hz) spectral efficiency.The validity and the dependability of the scheme were also analyzed.

  17. Diagnostic value of contrast-enhanced intraoperative Doppler sonography for cerebral arteriovenous malformations compared with angiography

    Institute of Scientific and Technical Information of China (English)

    XU Hong-zhi; QIN Zhi-yong; GU Yu-xiang; ZHOU Ping; CHEN Xian-cheng

    2010-01-01

    Background Intraoperative Doppler sonography has been used in the neurosurgical operating room for the localization and description of cerebral arteriovenous malformations (AVMs). This study aimed to investigate the clinical value of contrast-enhanced intraoperative Doppler sonography, including its ability to assess the location and identify of feeding arteries in patients with AVMs and to compare this method with angiography.Methods Twenty-three patients with cerebral AVMs who were diagnosed using angiography, were examined with contrast-enhanced intraoperative Doppler sonography. As an echo-enhancing agent, Sulphur Hexafluoride Microbubbles for Injection ("SonoVue") was administered intravenously in all patients. Sonogram results were reviewed and correlated with angiographic findings. For statistical analysis, the Wilcoxon signed-rank test was applied.Results Angiography identified 20 AVM lesions in the anterior or middle fossa and 3 in the posterior fossa.Contrast-enhanced intraoperative Doppler was somewhat less sensitive for only detecting 21/23 (91.3%) of the AVM lesions. Additionally, contrast-enhanced intraoperative Doppler slightly underestimated AVM size compared with angiographic findings but showed feeding arteries with sufficient acoustic properties. In 15 patients, angiography revealed a coincidental blood supply from another intracranial vessel, which was missed by contrast-enhanced intraoperative Doppler sonography.Conclusions In a limited group of patients with AVMs, contrast-enhanced intraoperative Doppler sonography was a less sensitive but useful and simple method for the detection of AVMs in contrast to angiography. No specific untoward effects were attributed to the use of "SonoVue" as a contrast-enhancing substance.

  18. Flow velocity measurement with the nonlinear acoustic wave scattering

    Science.gov (United States)

    Didenkulov, Igor; Pronchatov-Rubtsov, Nikolay

    2015-10-01

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

  19. Flow velocity measurement with the nonlinear acoustic wave scattering

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-28

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

  20. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton;

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  1. Springer Handbook of Acoustics

    CERN Document Server

    Rossing, Thomas D

    2007-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and others. The Springer Handbook of Acoustics is an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents spanning: animal acoustics including infrasound and ultrasound, environmental noise control, music and human speech and singing, physiological and psychological acoustics, architectural acoustics, physical and engineering acoustics, signal processing, medical acoustics, and ocean acoustics. This handbook reviews the most important areas of acoustics, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest rese...

  2. Acoustic Spatiality

    Directory of Open Access Journals (Sweden)

    Brandon LaBelle

    2012-06-01

    Full Text Available Experiences of listening can be appreciated as intensely relational, bringing us into contact with surrounding events, bodies and things. Given that sound propagates and expands outwardly, as a set of oscillations from a particular source, listening carries with it a sensual intensity, whereby auditory phenomena deliver intrusive and disruptive as well as soothing and assuring experiences. The physicality characteristic of sound suggests a deeply impressionistic, locational "knowledge structure" – that is, the ways in which listening affords processes of exchange, of being in the world, and from which we extend ourselves. Sound, as physical energy reflecting and absorbing into the materiality around us, and even one's self, provides a rich platform for understanding place and emplacement. Sound is always already a trace of location.Such features of auditory experience give suggestion for what I may call an acoustical paradigm – how sound sets in motion not only the material world but also the flows of the imagination, lending to forces of signification and social structure, and figuring us in relation to each other. The relationality of sound brings us into a steady web of interferences, each of which announces the promise or problematic of being somewhere.

  3. Acoustic Neurinomas

    Directory of Open Access Journals (Sweden)

    Mohammad Faraji Rad

    2011-01-01

    Full Text Available Acoustic neuromas (AN are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(VS causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumor is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few. The predominant clinical endpoints of AN treatment include tumor control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL. It is uncertain if treating a small tumor leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment.   In this paper we review the literature for the natural course, the treatment alternatives and the results of AN. Finally, we present our experience with a management strategy applied for more than 30 years.

  4. Doppler tomography in fusion plasmas and astrophysics

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  5. Acoustic source for generating an acoustic beam

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  6. DOPPLER ANALYSIS IN PREGNANCY INDUCED HYPERTENSION

    Directory of Open Access Journals (Sweden)

    Tushar

    2014-12-01

    Full Text Available A study of 50 cases was conducted to evaluate the role of Colour Doppler imaging in pregnancy induced hypertension with women over 28 weeks of gestation, the initial scan was performed immediately after the diagnosis of PIH to avoid any influence of treatment on Doppler evaluation. This study was aimed to analyze the blood flow in umbilical artery, maternal uterine artery & fetal middle cerebral artery using Doppler ultrasound.

  7. DOPPLER ANALYSIS IN PREGNANCY INDUCED HYPERTENSION

    OpenAIRE

    Tushar; Amit C

    2014-01-01

    A study of 50 cases was conducted to evaluate the role of Colour Doppler imaging in pregnancy induced hypertension with women over 28 weeks of gestation, the initial scan was performed immediately after the diagnosis of PIH to avoid any influence of treatment on Doppler evaluation. This study was aimed to analyze the blood flow in umbilical artery, maternal uterine artery & fetal middle cerebral artery using Doppler ultrasound.

  8. Doppler sonography of RA joints and LCAP

    OpenAIRE

    Kanno, Yukiko; Kobayashi, Hiroko; Suzuki, Eiji; Iwadate, Haruyo; Sasajima, Tomomi; Watanabe, Hiroshi; Ohira, Hiromasa

    2008-01-01

    Synovial vascularization in metacarpophalangeal joints of a patient with rheumatoid arthritis treated with leukocytapheresis (LCAP) was evaluated by Doppler sonography. After the treatment with LCAP, evaluation with American College of Rheumatology core set showed improvement, and the levels of C-reactive protein and serum amyloid A protein decreased. Power Doppler sonography demonstrated a reduction of color flow signals of the joints, and spectral Doppler sonography demonstrated an increase...

  9. Postoperative doppler evaluation of liver transplants

    OpenAIRE

    Rupan Sanyal; Zarzour, Jessica G.; Ganeshan, Dakshina M; Puneet Bhargava; Chandana G Lall; Mark D Little

    2014-01-01

    Doppler ultrasound plays an important role in the postoperative management of hepatic transplantation, by enabling early detection and treatment of various vascular complications. This article describes the normal Doppler findings following liver transplantation and reviews the imaging appearances of various vascular complications associated with it. The article also discusses transient waveform abnormalities, often seen on a post-transplant Doppler examination, and the importance of differen...

  10. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials

    Science.gov (United States)

    Shen, Jian Qi

    2016-08-01

    In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.

  11. Application of a laser Doppler vibrometer for air-water to subsurface signature detection

    Science.gov (United States)

    Land, Phillip; Roeder, James; Robinson, Dennis; Majumdar, Arun

    2015-05-01

    There is much interest in detecting a target and optical communications from an airborne platform to a platform submerged under water. Accurate detection and communications between underwater and aerial platforms would increase the capabilities of surface, subsurface, and air, manned and unmanned vehicles engaged in oversea and undersea activities. The technique introduced in this paper involves a Laser Doppler Vibrometer (LDV) for acousto-optic sensing for detecting acoustic information propagated towards the water surface from a submerged platform inside a 12 gallon water tank. The LDV probes and penetrates the water surface from an aerial platform to detect air-water surface interface vibrations caused by an amplifier to a speaker generating a signal generated from underneath the water surface (varied water depth from 1" to 8"), ranging between 50Hz to 5kHz. As a comparison tool, a hydrophone was used simultaneously inside the water tank for recording the acoustic signature of the signal generated between 50Hz to 5kHz. For a signal generated by a submerged platform, the LDV can detect the signal. The LDV detects the signal via surface perturbations caused by the impinging acoustic pressure field; proving a technique of transmitting/sending information/messages from a submerged platform acoustically to the surface of the water and optically receiving the information/message using the LDV, via the Doppler Effect, allowing the LDV to become a high sensitivity optical-acoustic device. The technique developed has much potential usage in commercial oceanography applications. The present work is focused on the reception of acoustic information from an object located underwater.

  12. Emboli detection using the Doppler ultrasound technique

    Institute of Scientific and Technical Information of China (English)

    WANG Yuanyuan; CHEN Xi; ZHANG Yu; WANG Weiqi

    2003-01-01

    Embolic detection is very important to the early diagnosis of vessel disease. The Doppler ultrasound technique is one of the common methods to detect the emboli non-invasively. When the emboli pass through the sample volume of the Doppler ultrasound instrument, there exist high intensity transient Doppler signals. Thus the emboli can be detected directly from the variation of Doppler signal amplitude. Since there may be some disturbance in the system, this general detection method has great limitation. To improve the accuracy of emboli auto-detection, several novel methods are studied to obtain the sensitive characteristic of the emboli signals using the new signal processing theories.

  13. Transcranial Doppler ultrasonography: From methodology to major clinical applications.

    Science.gov (United States)

    D'Andrea, Antonello; Conte, Marianna; Cavallaro, Massimo; Scarafile, Raffaella; Riegler, Lucia; Cocchia, Rosangela; Pezzullo, Enrica; Carbone, Andreina; Natale, Francesco; Santoro, Giuseppe; Caso, Pio; Russo, Maria Giovanna; Bossone, Eduardo; Calabrò, Raffaele

    2016-07-26

    Non-invasive Doppler ultrasonographic study of cerebral arteries [transcranial Doppler (TCD)] has been extensively applied on both outpatient and inpatient settings. It is performed placing a low-frequency (≤ 2 MHz) transducer on the scalp of the patient over specific acoustic windows, in order to visualize the intracranial arterial vessels and to evaluate the cerebral blood flow velocity and its alteration in many different conditions. Nowadays the most widespread indication for TCD in outpatient setting is the research of right to left shunting, responsable of so called "paradoxical embolism", most often due to patency of foramen ovale which is responsable of the majority of cryptogenic strokes occuring in patients younger than 55 years old. TCD also allows to classify the grade of severity of such shunts using the so called "microembolic signal grading score". In addition TCD has found many useful applications in neurocritical care practice. It is useful on both adults and children for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoidal haemorrhage (caused by aneurysm rupture or traumatic injury), traumatic brain injury, brain stem death. It is used also to evaluate cerebral hemodynamic changes after stroke. It also allows to investigate cerebral pressure autoregulation and for the clinical evaluation of cerebral autoregulatory reserve.

  14. Transcranial Doppler ultrasonography: From methodology to major clinical applications.

    Science.gov (United States)

    D'Andrea, Antonello; Conte, Marianna; Cavallaro, Massimo; Scarafile, Raffaella; Riegler, Lucia; Cocchia, Rosangela; Pezzullo, Enrica; Carbone, Andreina; Natale, Francesco; Santoro, Giuseppe; Caso, Pio; Russo, Maria Giovanna; Bossone, Eduardo; Calabrò, Raffaele

    2016-07-26

    Non-invasive Doppler ultrasonographic study of cerebral arteries [transcranial Doppler (TCD)] has been extensively applied on both outpatient and inpatient settings. It is performed placing a low-frequency (≤ 2 MHz) transducer on the scalp of the patient over specific acoustic windows, in order to visualize the intracranial arterial vessels and to evaluate the cerebral blood flow velocity and its alteration in many different conditions. Nowadays the most widespread indication for TCD in outpatient setting is the research of right to left shunting, responsable of so called "paradoxical embolism", most often due to patency of foramen ovale which is responsable of the majority of cryptogenic strokes occuring in patients younger than 55 years old. TCD also allows to classify the grade of severity of such shunts using the so called "microembolic signal grading score". In addition TCD has found many useful applications in neurocritical care practice. It is useful on both adults and children for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoidal haemorrhage (caused by aneurysm rupture or traumatic injury), traumatic brain injury, brain stem death. It is used also to evaluate cerebral hemodynamic changes after stroke. It also allows to investigate cerebral pressure autoregulation and for the clinical evaluation of cerebral autoregulatory reserve. PMID:27468332

  15. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... ANA Annual Reports Acoustic Neuroma Legacy Society Programs & Services Join/Renew Ways to Give ANA Discussion Forum ... ANA Annual Reports Acoustic Neuroma Legacy Society Programs & Services Search ANAUSA.org Connect with us! Educational Video ...

  16. Atlantic Herring Acoustic Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and...

  17. Cystic acoustic neuromas

    OpenAIRE

    Chitkara, Naveen; Chanda, Rakesh; Yadav, S. P. S.; N.K. Sharma

    2002-01-01

    Predominantly cystic acoustic neuromas are rare and they usually present with clinical and radiological features different from their more common solid counterparts. Two cases of cystic acoustic neuromas are reported here.

  18. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... is ANA? Mission Statement Board of Directors ANA Staff Medical Advisory Board News ANA Annual Reports Acoustic ... is ANA? Mission Statement Board of Directors ANA Staff Medical Advisory Board News ANA Annual Reports Acoustic ...

  19. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ...

  20. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Resources Patient Surveys Related Links Clinical Trials.gov Health Care Insurance Toolkit Additional Resources ANA Public Webinars © 2016 Acoustic Neuroma Association Acoustic Neuroma Association ® • ...

  1. High-frequency bottom-pressure and acoustic variations in a sea strait: internal wave turbulence

    NARCIS (Netherlands)

    van Haren, H.

    2012-01-01

    During a period of 3 days, an accurate bottom-pressure sensor and a four-beam acoustic Doppler current profiler (ADCP) were mounted in a bottom frame at 23 m in a narrow sea strait with dominant near-rectilinear tidal currents exceeding 1 m s(-1) in magnitude. The pressure record distinguishes small

  2. Methods of temperature measurement in a radio-acoustic tropospheric sounder

    Directory of Open Access Journals (Sweden)

    P. TRIVERO

    1976-06-01

    Full Text Available The temperature of the lower troposphere is inferred
    by measuring with a doppler radar the speed of a powerful acoustic wave,
    capable of periodically perturbing the index of refraction of air. Three
    methods for performing these measurements are described.

  3. Tutorial on architectural acoustics

    Science.gov (United States)

    Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

    2002-11-01

    This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).

  4. Airborne Differential Doppler Weather Radar

    Science.gov (United States)

    Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the

  5. Tablet based real-time Doppler spectrum processing

    OpenAIRE

    Dahl, Bjørn Rudi

    2014-01-01

    By utilizing mobile, low-cost Doppler ultrasound technology in developing countries, the mortality rate of unborn children, small children and pregnant women might be reduced. Two main Doppler techniques which are used in ultrasound are the Doppler spectrum and the Doppler audio. The Doppler spectrum is used for quantitative analysis of the blood-flow while the Doppler audio is used for guidance during recordingThis thesis presents the implementation of a real-time Dopplerspectrum generator a...

  6. Multimodal integration of micro-Doppler sonar and auditory signals for behavior classification with convolutional networks.

    Science.gov (United States)

    Dura-Bernal, Salvador; Garreau, Guillaume; Georgiou, Julius; Andreou, Andreas G; Denham, Susan L; Wennekers, Thomas

    2013-10-01

    The ability to recognize the behavior of individuals is of great interest in the general field of safety (e.g. building security, crowd control, transport analysis, independent living for the elderly). Here we report a new real-time acoustic system for human action and behavior recognition that integrates passive audio and active micro-Doppler sonar signatures over multiple time scales. The system architecture is based on a six-layer convolutional neural network, trained and evaluated using a dataset of 10 subjects performing seven different behaviors. Probabilistic combination of system output through time for each modality separately yields 94% (passive audio) and 91% (micro-Doppler sonar) correct behavior classification; probabilistic multimodal integration increases classification performance to 98%. This study supports the efficacy of micro-Doppler sonar systems in characterizing human actions, which can then be efficiently classified using ConvNets. It also demonstrates that the integration of multiple sources of acoustic information can significantly improve the system's performance.

  7. Acoustic elliptical cylindrical cloaks

    Institute of Scientific and Technical Information of China (English)

    Ma Hua; Qu Shao-Bo; Xu Zhuo; Wang Jia-Fu

    2009-01-01

    By making a comparison between the acoustic equations and the 2-dimensional (2D) Maxwell equations, we obtain the material parameter equations (MPE) for acoustic elliptical cylindrical cloaks. Both the theoretical results and the numerical results indicate that an elliptical cylindrical cloak can realize perfect acoustic invisibility when the spatial distributions of mass density and bulk modulus are exactly configured according to the proposed equations. The present work is the meaningful exploration of designing acoustic cloaks that are neither sphere nor circular cylinder in shape, and opens up possibilities for making complex and multiplex acoustic cloaks with simple models such as spheres, circular or elliptic cylinders.

  8. Observation of the Zero Doppler Effect

    Science.gov (United States)

    Ran, Jia; Zhang, Yewen; Chen, Xiaodong; Fang, Kai; Zhao, Junfei; Chen, Hong

    2016-04-01

    The normal Doppler effect has well-established applications in many areas of science and technology. Recently, a few experimental demonstrations of the inverse Doppler effect have begun to appear in negative-index metamaterials. Here we report an experimental observation of the zero Doppler effect, that is, no frequency shift irrespective of the relative motion between the wave signal source and the detector in a zero-index metamaterial. This unique phenomenon, accompanied by the normal and inverse Doppler effects, is generated by reflecting a wave from a moving discontinuity in a composite right/left-handed transmission line loaded with varactors when operating in the near zero-index passband, or the right/left-handed passband. This work has revealed a complete picture of the Doppler effect in metamaterials and may lead to potential applications in electromagnetic wave related metrology.

  9. Propagation of acoustic gravity waves excited by explosions

    International Nuclear Information System (INIS)

    Acoustic gravity waves excited by low-altitude nuclear explosions have been observed in the ionosphere, by H.F. Doppler soundings, at horizontal distances from the source between 100 and 1200 km. The characteristics of the initial shock wave, which is observed at short range, are progressively replaced by those of the atmospheric wave guide. In particular, the dispersion properties of the signal observed in the ionosphere at long range are those of the first acoustic and gravity modes. Detailed study of the propagation times to middle and long range shows that the wave guide is mainly excited by the focalisation of acoustic energy which is produced by non-linear mechanisms at an altitude of about 100 km and at a small horizontal distance from the explosion

  10. Color doppler sonography in thickened gallbladder wall

    International Nuclear Information System (INIS)

    The thickening of the gallbladder wall is a valuable finding for the diagnosis of cholecystitis, but may be seen in non-cholecystic disease as well as in acute or chronic cholecystitis. The purpose of this study is to determine the value of color Doppler sonography in differentiating the causes of thickened gallbladder wall. Ninety eight patients with thickened gallbladder wall(more than 3mm) which was not due to gallbladder cancer were prospectively evaluated with color Doppler sonography. Sixty-six cases, confirmed by pathologic reports and clinical records, were analyzed for correlation between thickened gallbladder wall and color flow signal according to the underlying causes. Of the 66 patients, 28 cases were cholecystitis and 38 cases had non-cholecystic causes such as liver cirrhosis, ascites, hepatitis, pancreatitis, renal failure, and hypoalbuminemia. Of the 28 patients with cholecystitis(12 acute, 16 chronic), 23(82%) had color Doppler flow signals in the thickened gallbladder wall. Of the 38 patients with non-cholecystic causes, eight(21%) had color Doppler flow signals. There was a statistically significant difference of color Doppler flow signals between the cholecystitis and non-cholecystic groups(p=0.0001). No significant difference of color Doppler flow signals was found between cases of acute and chronic cholecystitis. Of the 23 patients with color Doppler flow signals in 28 cases of cholecystitis, 18(78.3%) showed a linear pattern and five(21.7%) showed a spotty pattern. Of the eight patients with color Doppler flow signals in the 38 non-cholecystic cases, four(50%) showed a linear pattern and four(50%) showed a spotty pattern. In cholecystitis, a linear color Doppler flow signal pattern is a much more frequent finding than a spotty pattern. Color Doppler sonography is a useful and adequate method for determining whether a thickened gallbladder wall is the result of cholecystitis or has non-cholecystic causes

  11. ACOUSTICAL STANDARDS NEWS.

    Science.gov (United States)

    Stremmel, Neil; Struck, Christopher J

    2016-07-01

    American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, please contact Neil Stremmel.Comments are welcomed on all material in Acoustical Standards News.This Acoustical Standards News section in JASA, as well as the National Catalog of Acoustical Standards and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org. PMID:27475185

  12. Acoustic streaming in microchannels

    DEFF Research Database (Denmark)

    Tribler, Peter Muller

    , the acoustic streaming flow, and the forces on suspended microparticles. The work is motivated by the application of particle focusing by acoustic radiation forces in medical, environmental and food sciences. Here acoustic streaming is most often unwanted, because it limits the focusability of particles...... work. Based on first- and second-order perturbation theory, assuming small acoustic amplitudes, we derived the time-dependent governing equations under adiabatic conditions. The adiabatic first- and second-order equations are solved analytically for the acoustic field between two orthogonally......-of-the-art in the field. Furthermore, the analytical solution for the acoustic streaming in rectangular channels with arbitrary large height-to-width ratios is derived. This accommodates the analytical theory of acoustic streaming to applications within acoustofluidics....

  13. Radar Sensor Networks: Algorithms for Waveform Design and Diversity with Application to ATR with Delay-Doppler Uncertainty

    Directory of Open Access Journals (Sweden)

    Qilian Liang

    2007-01-01

    Full Text Available Automatic target recognition (ATR in target search phase is very challenging because the target range and mobility are not yet perfectly known, which results in delay-Doppler uncertainty. In this paper, we firstly perform some theoretical studies on radar sensor network (RSN design based on linear frequency modulation (LFM waveform: (1 the conditions for waveform coexistence, (2 interferences among waveforms in RSN, (3 waveform diversity in RSN. Then we apply RSN to ATR with delay-Doppler uncertainty and propose maximum-likeihood (ML ATR algorithms for fluctuating targets and nonfluctuating targets. Simulation results show that our RSN vastly reduces the ATR error compared to a single radar system in ATR with delay-Doppler uncertainty. The proposed waveform design and diversity algorithms can also be applied to active RFID sensor networks and underwater acoustic sensor networks.

  14. Investigating the use of the acousto-optic effect for acoustic holography

    DEFF Research Database (Denmark)

    Torras Rosell, Antoni; Fernandez Grande, Efren; Jacobsen, Finn;

    2012-01-01

    Recent studies have demonstrated that the acousto-optic effect, that is, the interaction between sound and light, can be used as a means to visualize acoustic fields in the audible frequency range. The changes of density caused by sound waves propagating in air induce phase shifts to a laser beam...... that travels through the acoustic field. This phenomenon can in practice be captured with a laser Doppler vibrometer (LDV), and the pressure distribution of the acoustic field can be reconstructed using tomography. The present work investigates the potential of the acousto-optic effect in acoustic holography....... Two different holographic methods are examined for this purpose. One method first reconstructs the hologram plane using acousto-optic tomography and then propagates it using conventional near-field acoustic holography (NAH). The other method exploits the so-called Fourier Slice Theorem and bases all...

  15. Optical Doppler tomography and spectral Doppler imaging of localized ischemic stroke in a mouse model

    Science.gov (United States)

    Yu, Lingfeng; Nguyen, Elaine; Liu, Gangjun; Rao, Bin; Choi, Bernard; Chen, Zhongping

    2010-02-01

    We present a combined optical Doppler tomography/spectral Doppler imaging modality to quantitatively evaluate the dynamic blood circulation and the artery blockage before and after a localized ischemic stroke in a mouse model. Optical Doppler Tomography (ODT) combines the Doppler principle with optical coherence tomography for noninvasive localization and measurement of particle flow velocity in highly scattering media with micrometer scale spatial resolution. Spectral Doppler imaging (SDI) provides complementary temporal flow information to the spatially distributed flow information of Doppler imaging. Fast, repeated, ODT scans across an entire vessel were performed to record flow dynamic information with high temporal resolution of cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time for scatters within the imaging volume using spectral Doppler waveforms. Furthermore, vascular conditions can be quantified with various Doppler-angle-independent flow indices. Non-invasive in-vivo mice experiments were performed to evaluate microvascular blood circulation of a localized ischemic stroke mouse model.

  16. Doppler method leak detection for LMFBR steam generators. Pt. 1. Experimental results of bubble detection using small models

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Hiromichi [Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab

    1999-05-01

    To prevent the expansion of the tube damage and to maintain structural integrity in the steam generators (SGs) of fast breeder reactors (FBRs), it is necessary to detect precisely and immediately the leakage of water from heat transfer tubes. Therefore, an active acoustic method was developed. Previous studies have revealed that in practical steam generators the active acoustic method can detect bubbles of 10 l/s within 10 seconds. To prevent the expansion of damage to neighboring tubes, it is necessary to detect smaller leakages of water from the heat transfer tubes. The Doppler method is designed to detect small leakages and to find the source of the leak before damage spreads to neighboring tubes. To evaluate the relationship between the detection sensitivity of the Doppler method and the bubble volume and bubble size, the structural shapes and bubble flow conditions were investigated experimentally, using a small structural model. The results show that the Doppler method can detect the bubbles under bubble flow conditions, and it is sensitive enough to detect small leakages within a short time. The doppler method thus has strong potential for the detection of water leakage in SGs. (author)

  17. Staggered Multiple-PRF Ultrafast Color Doppler.

    Science.gov (United States)

    Posada, Daniel; Poree, Jonathan; Pellissier, Arnaud; Chayer, Boris; Tournoux, Francois; Cloutier, Guy; Garcia, Damien

    2016-06-01

    Color Doppler imaging is an established pulsed ultrasound technique to visualize blood flow non-invasively. High-frame-rate (ultrafast) color Doppler, by emissions of plane or circular wavefronts, allows severalfold increase in frame rates. Conventional and ultrafast color Doppler are both limited by the range-velocity dilemma, which may result in velocity folding (aliasing) for large depths and/or large velocities. We investigated multiple pulse-repetition-frequency (PRF) emissions arranged in a series of staggered intervals to remove aliasing in ultrafast color Doppler. Staggered PRF is an emission process where time delays between successive pulse transmissions change in an alternating way. We tested staggered dual- and triple-PRF ultrafast color Doppler, 1) in vitro in a spinning disc and a free jet flow, and 2) in vivo in a human left ventricle. The in vitro results showed that the Nyquist velocity could be extended to up to 6 times the conventional limit. We found coefficients of determination r(2) ≥ 0.98 between the de-aliased and ground-truth velocities. Consistent de-aliased Doppler images were also obtained in the human left heart. Our results demonstrate that staggered multiple-PRF ultrafast color Doppler is efficient for high-velocity high-frame-rate blood flow imaging. This is particularly relevant for new developments in ultrasound imaging relying on accurate velocity measurements.

  18. Rotational Doppler effect in nonlinear optics

    Science.gov (United States)

    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.

  19. Doppler effect-based fiber-optic sensor and its application in ultrasonic detection

    Science.gov (United States)

    Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

    2009-06-01

    Based on the Doppler effect of light wave transmission in optical fiber, Doppler effect-based fiber-optic (FOD) sensor possesses outstanding advantages in acquiring vibration/acoustic waves with high sensitivity. Furthermore, when shape of the FOD sensor was properly selected, its sensitivity was bonding direction-independent, namely non-directionality. In this paper, characteristics of the FOD sensor were investigated for the purpose of ultrasonic detection. A piezoelectric wafer was applied as an actuator to excite Lamb waves, a kind of ultrasonic wave, in an aluminum-alloy plate. Features of the ultrasonic wave signals, collected using a number of spiral FOD sensors with various inner diameters and outer diameters, were compared to investigate characteristics of FOD sensor. Amplitude curves of the FOD sensors were hereby obtained for the future applications in ultrasonic acquisition. The results demonstrated that sensitivity of the spiral FOD sensor with longer optical fiber length was higher than that with shorter fiber length.

  20. Estimating the Doppler centroid of SAR data

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang

    1989-01-01

    After reviewing frequency-domain techniques for estimating the Doppler centroid of synthetic-aperture radar (SAR) data, the author describes a time-domain method and highlights its advantages. In particular, a nonlinear time-domain algorithm called the sign-Doppler estimator (SDE) is shown to have...... attractive properties. An evaluation based on an existing SEASAT processor is reported. The time-domain algorithms are shown to be extremely efficient with respect to requirements on calculations and memory, and hence they are well suited to real-time systems where the Doppler estimation is based on raw SAR...

  1. Springer handbook of acoustics

    CERN Document Server

    2014-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and electronics. The Springer Handbook of Acoustics is also in his 2nd edition an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents. This new edition of the Handbook features over 11 revised and expanded chapters, new illustrations, and 2 new chapters covering microphone arrays  and acoustic emission.  Updated chapters contain the latest research and applications in, e.g. sound propagation in the atmosphere, nonlinear acoustics in fluids, building and concert hall acoustics, signal processing, psychoacoustics, computer music, animal bioacousics, sound intensity, modal acoustics as well as new chapters on microphone arrays an...

  2. Vibro-acoustics

    CERN Document Server

    Nilsson, Anders

    2015-01-01

    This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and inter...

  3. Model of propagation of acoustic pulses caused by underground nuclear explosion and theirs influence on the ionosphere

    Science.gov (United States)

    Krasnov, V.; Drobzheva, Y.

    2003-04-01

    To describe the propagation of an acoustic pulse through the inhomogeneity atmosphere we developed new equation and correspondent computer simulation code. The equation takes into account nonlinear effects, inhomogeneities of the atmosphere, absorption, expansion of a wave acoustic front, etc. The model includes subroutine of vertical movement of earth surface during an underground nuclear explosion (we use an empirical model), subroutine of acoustic pulse generation by a spall zone, subroutine of propagation of acoustic pulse up to the ionospheric height, subroutine of acoustic wave influence on the ionospheric plasma, subroutine of ionospheric perturbation influence on Doppler frequency of a radio wave. All calculations take into account geomagnetic field and neutral wind. The data measurement of acoustic pulses at heights of the ionosphere with helping Doppler radio sounding were used to test the model. We used data of Doppler shift records which were obtained during 9 underground nuclear explosion for 16 traces of radio sounding of the ionoshphere. Coefficients correlation between calculated and experimental forms is 0.7-0.94.

  4. Shallow Water Acoustic Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports experimental research where high-frequency acoustic scattering and surface vibration measurements of fluid-loaded and non-fluid-loaded structures...

  5. Low frequency acoustic microscope

    Science.gov (United States)

    Khuri-Yakub, Butrus T.

    1986-11-04

    A scanning acoustic microscope is disclosed for the detection and location of near surface flaws, inclusions or voids in a solid sample material. A focused beam of acoustic energy is directed at the sample with its focal plane at the subsurface flaw, inclusion or void location. The sample is scanned with the beam. Detected acoustic energy specularly reflected and mode converted at the surface of the sample and acoustic energy reflected by subsurface flaws, inclusions or voids at the focal plane are used for generating an interference signal which is processed and forms a signal indicative of the subsurface flaws, inclusions or voids.

  6. Handbook of Engineering Acoustics

    CERN Document Server

    Möser, Michael

    2013-01-01

    This book examines the physical background of engineering acoustics, focusing on empirically obtained engineering experience as well as on measurement techniques and engineering methods for prognostics. Its goal is not only to describe the state of art of engineering acoustics but also to give practical help to engineers in order to solve acoustic problems. It deals with the origin, the transmission and the methods of the abating different kinds of air-borne and structure-borne sounds caused by various mechanisms – from traffic to machinery and flow-induced sound. In addition the modern aspects of room and building acoustics, as well as psychoacoustics and active noise control, are covered.

  7. Localized acoustic surface modes

    Science.gov (United States)

    Farhat, Mohamed; Chen, Pai-Yen; Bağcı, Hakan

    2016-04-01

    We introduce the concept of localized acoustic surface modes. We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

  8. Localized Acoustic Surface Modes

    KAUST Repository

    Farhat, Mohamed

    2015-08-04

    We introduce the concept of localized acoustic surface modes (ASMs). We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. INSTANTANEOUS DOPPLER FREQUENCY FOR SQUINT SAR IMAGING

    Institute of Scientific and Technical Information of China (English)

    Liu Guangyan; Huang Shunji

    2003-01-01

    Instantaneous Doppler frequency for squint SAR imaging has been found with ChirpScaling Algorithm (CSA). Because the azimuth sample is not perpendicular to the range sample,the range signal must impact on the azimuth signal in the squint SAR data processing, andthe different slant range targets have different Doppler frequencies. From the mathematicalmodel of SAR echo signal, this paper carefully analyzes the instantaneous azimuth frequency, theinstantaneous Doppler frequency component of the azimuth frequency and the impact of rangechirp on azimuth frequency, which explains that Doppler frequency should be properly selected forcorrect SAR imaging in the squint SAR. The results of point target simulation experiments showthat the way is reasonable for the squint SAR and can effectively complete range compressionand azimuth focusing, and improve images' quality.

  11. High Throughput Direct Detection Doppler Lidar Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lite Cycles, Inc. (LCI) proposes to develop a direct-detection Doppler lidar (D3L) technology called ELITE that improves the system optical throughput by more than...

  12. Doppler spectral characteristics of infrainguinal vein bypasses

    DEFF Research Database (Denmark)

    Nielsen, Tina G; von Jessen, F; Sillesen, H;

    1993-01-01

    With the aim of assessing the velocity profile of femoropopliteal and femorocrural vein bypasses, 128 patients undergoing infrainguinal vein bypass surgery entered a postoperative Duplex surveillance protocol, which included clinical assessment and Duplex scanning, using Doppler spectral analysis...

  13. High range resolution micro-Doppler analysis

    Science.gov (United States)

    Cammenga, Zachary A.; Smith, Graeme E.; Baker, Christopher J.

    2015-05-01

    This paper addresses use of the micro-Doppler effect and the use of high range-resolution profiles to observe complex targets in complex target scenes. The combination of micro-Doppler and high range-resolution provides the ability to separate the motion of complex targets from one another. This ability leads to the differentiation of targets based on their micro-Doppler signatures. Without the high-range resolution, this would not be possible because the individual signatures would not be separable. This paper also addresses the use of the micro-Doppler information and high range-resolution profiles to generate an approximation of the scattering properties of a complex target. This approximation gives insight into the structure of the complex target and, critically, is created without using a pre-determined target model.

  14. Student Microwave Experiments Involving the Doppler Effect.

    Science.gov (United States)

    Weber, F. Neff; And Others

    1980-01-01

    Described is the use of the Doppler Effect with microwaves in the measurement of the acceleration due to gravity of falling objects. The experiments described add to the repertoire of quantitative student microwave experiments. (Author/DS)

  15. What Is an Acoustic Neuroma

    Science.gov (United States)

    ... org Connect with us! What is an Acoustic Neuroma? Each heading slides to reveal information. Important Points ... Neuroma Important Points To Know About an Acoustic Neuroma An acoustic neuroma, also called a vestibular schwannoma, ...

  16. Doppler micro sense and avoid radar

    Science.gov (United States)

    Gorwara, Ashok; Molchanov, Pavlo; Asmolova, Olga

    2015-10-01

    There is a need for small Sense and Avoid (SAA) systems for small and micro Unmanned Aerial Systems (UAS) to avoid collisions with obstacles and other aircraft. The proposed SAA systems will give drones the ability to "see" close up and give them the agility to maneuver through tight areas. Doppler radar is proposed for use in this sense and avoid system because in contrast to optical or infrared (IR) systems Doppler can work in more harsh conditions such as at dusk, and in rain and snow. And in contrast to ultrasound based systems, Doppler can better sense small sized obstacles such as wires and it can provide a sensing range from a few inches to several miles. An SAA systems comprised of Doppler radar modules and an array of directional antennas that are distributed around the perimeter of the drone can cover the entire sky. These modules are designed so that they can provide the direction to the obstacle and simultaneously generate an alarm signal if the obstacle enters within the SAA system's adjustable "Protection Border". The alarm signal alerts the drone's autopilot to automatically initiate an avoidance maneuver. A series of Doppler radar modules with different ranges, angles of view and transmitting power have been designed for drones of different sizes and applications. The proposed Doppler radar micro SAA system has simple circuitry, works from a 5 volt source and has low power consumption. It is light weight, inexpensive and it can be used for a variety of small unmanned aircraft.

  17. The Doppler effect in NMR spectroscopy.

    Science.gov (United States)

    Guéron, Maurice

    2003-02-01

    An NMR sample may be subject to motions, such as those due to sample spinning or to liquid flow. Is the spectrum of such a sample affected by the Doppler effect? The question arises because, instrumental dimensions being much shorter than the wavelength, it is the near-field of the precessing magnetic moment which couples to the receiver coil, rather than the radiated far-field. We expand the near-field into plane propagating waves. For each such wave there is another one with the same amplitude, propagating in the opposite direction. The Doppler shifts are therefore equal and opposite. In the model case of a small fluid sample moving with constant velocity, this leads to a distribution of Doppler shifts which is symmetrical with respect to the unshifted frequency: there is no net spectral shift. We examine the possibility of observing the Doppler distribution in this case. We also consider the case of thermal motion of a gas. We draw attention to the resolved Doppler splitting of molecular rotational transitions in a supersonic burst as observed in a microwave resonator. We also mention briefly the Doppler effect in molecular beam spectroscopy.

  18. Doppler synthetic aperture hitchhiker imaging

    International Nuclear Information System (INIS)

    In this paper we consider passive airborne receivers that use backscattered signals from sources of opportunity transmitting single-frequency or ultra-narrowband waveforms. Because of its combined passive synthetic aperture and the single-frequency nature of the transmitted waveforms, we refer to the system under consideration as Doppler synthetic aperture hitchhiker (DSAH). We present a novel image formation method for DSAH. Our method first correlates the windowed signal obtained from one receiver with the windowed, filtered, scaled and translated version of the received signal from another receiver. This processing removes the transmitter-related variables from the phase of the Fourier integral operator that maps the radiance of the scene to the correlated signal. Next, we use microlocal analysis to reconstruct the scene radiance by the weighted backprojection of the correlated signal. The image reconstruction method is applicable to both cooperative and non-cooperative sources of opportunity using one or more airborne receivers. It has the desirable property of preserving the visible edges of the scene radiance. Additionally, it is an analytic reconstruction technique that can be made computationally efficient. We present numerical simulations to demonstrate the performance of the image reconstruction method and to verify the theoretical results

  19. with Ultrasound Color Doppler Imaging

    Directory of Open Access Journals (Sweden)

    Shin Takayama

    2012-01-01

    Full Text Available Color Doppler imaging (CDI can be used to noninvasively create images of human blood vessels and quantitatively evaluate blood flow in real-time. The purpose of this study was to assess the effects of acupuncture on the blood flow of the peripheral, mesenteric, and retrobulbar arteries by CDI. Statistical significance was defined as P values less than 0.05. Blood flow in the radial and brachial arteries was significantly lower during needle stimulation on LR3 than before in healthy volunteers, but was significantly higher after needle stimulation than before. LR3 stimulation also resulted in a significant decrease in the vascular resistance of the short posterior ciliary artery and no significant change of blood flow through the superior mesenteric artery (SMA during acupuncture. In contrast, ST36 stimulation resulted in a significant increase in blood flow through the SMA and no significant change in the vascular resistance of the retrobulbar arteries. Additionally, acupuncture at previously determined acupoints in patients with open-angle glaucoma led to a significant reduction in the vascular resistance of the central retinal artery and short posterior ciliary artery. Our results suggest that acupuncture can affect blood flow of the peripheral, mesenteric, and retrobulbar arteries, and CDI can be useful to evaluate hemodynamic changes by acupuncture.

  20. Predicting Acoustics in Class Rooms

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge; Rindel, Jens Holger

    2005-01-01

    Typical class rooms have fairly simple geometries, even so room acoustics in this type of room is difficult to predict using today's room acoustic computer modeling software. The reasons why acoustics of class rooms are harder to predict than acoustics of complicated concert halls might be explai......Typical class rooms have fairly simple geometries, even so room acoustics in this type of room is difficult to predict using today's room acoustic computer modeling software. The reasons why acoustics of class rooms are harder to predict than acoustics of complicated concert halls might...... with surface scattering is presented. Each of the two scattering effects is modeled as frequency dependent functions....

  1. Chromospheric heating by acoustic waves compared to radiative cooling

    CERN Document Server

    Sobotka, M; Švanda, M; Jurčák, J; del Moro, D; Berrilli, F

    2016-01-01

    Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of solar atmosphere. A weak chromospheric plage near a large solar pore NOAA 11005 was observed on October 15, 2008 in the lines Fe I 617.3 nm and Ca II 853.2 nm with the Interferometric Bidimemsional Spectrometer (IBIS) attached to the Dunn Solar Telescope. Analyzing the Ca II observations with spatial and temporal resolutions of 0.4" and 52 s, the energy deposited by acoustic waves is compared with that released by radiative losses. The deposited acoustic flux is estimated from power spectra of Doppler oscillations measured in the Ca II line core. The radiative losses are calculated using a grid of seven 1D hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of maps of radiative losses and acoustic flux is 72 %. In quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only of about 15 %. In active areas with photospheric ma...

  2. Ocean acoustic reverberation tomography.

    Science.gov (United States)

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography.

  3. Acoustic Signals and Systems

    DEFF Research Database (Denmark)

    2008-01-01

    The Handbook of Signal Processing in Acoustics will compile the techniques and applications of signal processing as they are used in the many varied areas of Acoustics. The Handbook will emphasize the interdisciplinary nature of signal processing in acoustics. Each Section of the Handbook...... will present topics on signal processing which are important in a specific area of acoustics. These will be of interest to specialists in these areas because they will be presented from their technical perspective, rather than a generic engineering approach to signal processing. Non-specialists, or specialists...... from different areas, will find the self-contained chapters accessible and will be interested in the similarities and differences between the approaches and techniques used in different areas of acoustics....

  4. Ocean acoustic hurricane classification.

    Science.gov (United States)

    Wilson, Joshua D; Makris, Nicholas C

    2006-01-01

    Theoretical and empirical evidence are combined to show that underwater acoustic sensing techniques may be valuable for measuring the wind speed and determining the destructive power of a hurricane. This is done by first developing a model for the acoustic intensity and mutual intensity in an ocean waveguide due to a hurricane and then determining the relationship between local wind speed and underwater acoustic intensity. From this it is shown that it should be feasible to accurately measure the local wind speed and classify the destructive power of a hurricane if its eye wall passes directly over a single underwater acoustic sensor. The potential advantages and disadvantages of the proposed acoustic method are weighed against those of currently employed techniques. PMID:16454274

  5. Cochlear bionic acoustic metamaterials

    Science.gov (United States)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Fu, Gang; Bai, Changan

    2014-11-01

    A design of bionic acoustic metamaterial and acoustic functional devices was proposed by employing the mammalian cochlear as a prototype. First, combined with the experimental data in previous literatures, it is pointed out that the cochlear hair cells and stereocilia cluster are a kind of natural biological acoustic metamaterials with the negative stiffness characteristics. Then, to design the acoustic functional devices conveniently in engineering application, a simplified parametric helical structure was proposed to replace actual irregular cochlea for bionic design, and based on the computational results of such a bionic parametric helical structure, it is suggested that the overall cochlear is a local resonant system with the negative dynamic effective mass characteristics. There are many potential applications in the bandboard energy recovery device, cochlear implant, and acoustic black hole.

  6. Computational Ocean Acoustics

    CERN Document Server

    Jensen, Finn B; Porter, Michael B; Schmidt, Henrik

    2011-01-01

    Since the mid-1970s, the computer has played an increasingly pivotal role in the field of ocean acoustics. Faster and less expensive than actual ocean experiments, and capable of accommodating the full complexity of the acoustic problem, numerical models are now standard research tools in ocean laboratories. The progress made in computational ocean acoustics over the last thirty years is summed up in this authoritative and innovatively illustrated new text. Written by some of the field's pioneers, all Fellows of the Acoustical Society of America, Computational Ocean Acoustics presents the latest numerical techniques for solving the wave equation in heterogeneous fluid–solid media. The authors discuss various computational schemes in detail, emphasizing the importance of theoretical foundations that lead directly to numerical implementations for real ocean environments. To further clarify the presentation, the fundamental propagation features of the techniques are illustrated in color. Computational Ocean A...

  7. Flat acoustic lens by acoustic grating with curled slits

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Pai; Xiao, Bingmu; Wu, Ying, E-mail: ying.wu@kaust.edu.sa

    2014-10-03

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry–Perot resonance. - Highlights: • Expression of transmission coefficient of an acoustic grating with curled slits. • Non-dispersive and tunable effective medium parameters for the acoustic grating. • A flat acoustic focusing lens with gradient index by using the acoustic grating.

  8. Acoustic mapping velocimetry

    Science.gov (United States)

    Muste, M.; Baranya, S.; Tsubaki, R.; Kim, D.; Ho, H.; Tsai, H.; Law, D.

    2016-05-01

    Knowledge of sediment dynamics in rivers is of great importance for various practical purposes. Despite its high relevance in riverine environment processes, the monitoring of sediment rates remains a major and challenging task for both suspended and bed load estimation. While the measurement of suspended load is currently an active area of testing with nonintrusive technologies (optical and acoustic), bed load measurement does not mark a similar progress. This paper describes an innovative combination of measurement techniques and analysis protocols that establishes the proof-of-concept for a promising technique, labeled herein Acoustic Mapping Velocimetry (AMV). The technique estimates bed load rates in rivers developing bed forms using a nonintrusive measurements approach. The raw information for AMV is collected with acoustic multibeam technology that in turn provides maps of the bathymetry over longitudinal swaths. As long as the acoustic maps can be acquired relatively quickly and the repetition rate for the mapping is commensurate with the movement of the bed forms, successive acoustic maps capture the progression of the bed form movement. Two-dimensional velocity maps associated with the bed form migration are obtained by implementing algorithms typically used in particle image velocimetry to acoustic maps converted in gray-level images. Furthermore, use of the obtained acoustic and velocity maps in conjunction with analytical formulations (e.g., Exner equation) enables estimation of multidirectional bed load rates over the whole imaged area. This paper presents a validation study of the AMV technique using a set of laboratory experiments.

  9. Acoustic sniper localization system

    Science.gov (United States)

    Prado, Gervasio; Dhaliwal, Hardave; Martel, Philip O.

    1997-02-01

    Technologies for sniper localization have received increased attention in recent months as American forces have been deployed to various trouble spots around the world. Among the technologies considered for this task acoustics is a natural choice for various reasons. The acoustic signatures of gunshots are loud and distinctive, making them easy to detect even in high noise background environments. Acoustics provides a passive sensing technology with excellent range and non line of sight capabilities. Last but not least, an acoustic sniper location system can be built at a low cost with off the shelf components. Despite its many advantages, the performance of acoustic sensors can degrade under adverse propagation conditions. Localization accuracy, although good, is usually not accurate enough to pinpoint a sniper's location in some scenarios (for example which widow in a building or behind which tree in a grove). For these more demanding missions, the acoustic sensor can be used in conjunction with an infra red imaging system that detects the muzzle blast of the gun. The acoustic system can be used to cue the pointing system of the IR camera in the direction of the shot's source.

  10. From Architectural Acoustics to Acoustical Architecture Using Computer Simulation

    OpenAIRE

    Schmidt, Anne Marie Due; KIRKEGAARD, Poul Henning

    2005-01-01

    Architectural acoustics design has in the past been based on simple design rules. However, with a growing complexity in architectural acoustics and the emergence of room acoustic simulation programmes with considerable potential, it is now possible to subjectively analyse and evaluate acoustic properties prior to the actual construction of a building. With the right tools applied, acoustic design can become an integral part of the architectural design process. The aim of this paper is to inve...

  11. Underwater Applications of Acoustical Holography

    Directory of Open Access Journals (Sweden)

    P. C. Mehta

    1984-01-01

    Full Text Available The paper describes the basic technique of acoustical holography. Requirements for recording the acoustical hologram are discussed with its ability for underwater imaging in view. Some practical systems for short-range and medium-range imaging are described. The advantages of acoustical holography over optical imaging, acoustical imaging and sonars are outlined.

  12. Arm locking with Doppler estimation errors

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. An acoustic spacetime and the Lorentz transformation in aeroacoustics

    CERN Document Server

    Gregory, Alastair Logan; Agarwal, Anurag; Lasenby, Joan

    2014-01-01

    This paper introduces acoustic space-time and Geometric Algebra as a new theoretical framework for modelling aeroacoustic phenomena. This new framework is applied to sound propagation in uniform flows. The problem is modelled by means of transformations that turn the convected wave equation into an ordinary wave equation, in either time-space coordinates or frequency-wavenumber coordinates. The transformations are shown to combine a Galilean transformation with a Lorentz transformation and geometrical and physical interpretations are provided. The Lorentzian frame is the natural frame for describing acoustic waves in uniform flow. A key feature of this frame is that it combines space and time in a way that is best described using a hyperbolic geometry. The power of this new theoretical framework is illustrated by providing simple derivations for two classical aeroacoustic problems: the free-field Greens function for the convected wave equation and the Doppler shift for a stationary observer and a source in un...

  14. Wayside acoustic diagnosis of defective train bearings based on signal resampling and information enhancement

    Science.gov (United States)

    He, Qingbo; Wang, Jun; Hu, Fei; Kong, Fanrang

    2013-10-01

    The diagnosis of train bearing defects plays a significant role to maintain the safety of railway transport. Among various defect detection techniques, acoustic diagnosis is capable of detecting incipient defects of a train bearing as well as being suitable for wayside monitoring. However, the wayside acoustic signal will be corrupted by the Doppler effect and surrounding heavy noise. This paper proposes a solution to overcome these two difficulties in wayside acoustic diagnosis. In the solution, a dynamically resampling method is firstly presented to reduce the Doppler effect, and then an adaptive stochastic resonance (ASR) method is proposed to enhance the defective characteristic frequency automatically by the aid of noise. The resampling method is based on a frequency variation curve extracted from the time-frequency distribution (TFD) of an acoustic signal by dynamically minimizing the local cost functions. For the ASR method, the genetic algorithm is introduced to adaptively select the optimal parameter of the multiscale noise tuning (MST)-based stochastic resonance (SR) method. The proposed wayside acoustic diagnostic scheme combines signal resampling and information enhancement, and thus is expected to be effective in wayside defective bearing detection. The experimental study verifies the effectiveness of the proposed solution.

  15. Preprocessing of ionospheric echo Doppler spectra

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; ZHAO Zhengyu; WANG Feng; SU Fanfan

    2007-01-01

    The real-time information of the distant ionosphere can be acquired by using the Wuhan ionospheric oblique backscattering sounding system(WIOBSS),which adopts a discontinuous wave mechanism.After the characteristics of the ionospheric echo Doppler spectra were analyzed,the signal preprocessing was developed in this paper,which aimed at improving the Doppler spectra.The results indicate that the preprocessing not only makes the system acquire a higher ability of target detection but also suppresses the radio frequency interference by 6-7 dB.

  16. Observation of the inverse Doppler effect.

    Science.gov (United States)

    Seddon, N; Bearpark, T

    2003-11-28

    We report experimental observation of an inverse Doppler shift, in which the frequency of a wave is increased on reflection from a receding boundary. This counterintuitive effect has been produced by reflecting a wave from a moving discontinuity in an electrical transmission line. Doppler shifts produced by this system can be varied in a reproducible manner by electronic control of the transmission line and are typically five orders of magnitude greater than those produced by solid objects with kinematic velocities. Potential applications include the development of tunable and multifrequency radiation sources.

  17. Reversed Doppler effect in photonic crystals.

    Science.gov (United States)

    Reed, Evan J; Soljacić, Marin; Joannopoulos, John D

    2003-09-26

    Nonrelativistic reversed Doppler shifts have never been observed in nature and have only been speculated to occur in pathological systems with simultaneously negative effective permittivity and permeability. This Letter presents a different, new physical phenomenon that leads to a nonrelativistic reversed Doppler shift in light. It arises when light is reflected from a moving shock wave propagating through a photonic crystal. In addition to reflection of a single frequency, multiple discrete reflected frequencies or a 10 GHz periodic modulation can also be observed when a single carrier frequency of wavelength 1 microm is incident.

  18. Ocean acoustic reverberation tomography.

    Science.gov (United States)

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  19. Acoustic integrated extinction

    CERN Document Server

    Norris, Andrew N

    2015-01-01

    The integrated extinction (IE) is defined as the integral of the scattering cross-section as a function of wavelength. Sohl et al. [1] derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency.

  20. Autonomous Acoustic Receiver System

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Collects underwater acoustic data and oceanographic data. Data are recorded onboard an ocean buoy and can be telemetered to a remote ship or shore station...

  1. Thermal Acoustic Fatigue Apparatus

    Data.gov (United States)

    Federal Laboratory Consortium — The Thermal Acoustic Fatigue Apparatus (TAFA) is a progressive wave tube test facility that is used to test structures for dynamic response and sonic fatigue due to...

  2. Acoustic Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  3. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... treatment Summary Types Of Post-treatment Issues Resources Medical Resources Considerations When Selecting a Healthcare Professional Healthcare ... ANA? Mission Statement Board of Directors ANA Staff Medical Advisory Board News ANA Annual Reports Acoustic Neuroma ...

  4. Acoustics lecturing in Mexico

    Science.gov (United States)

    Beristain, Sergio

    2002-11-01

    Some thirty years ago acoustics lecturing started in Mexico at the National Polytechnic Institute in Mexico City, as part of the Bachelor of Science degree in Communications and Electronics Engineering curricula, including the widest program on this field in the whole country. This program has been producing acoustics specialists ever since. Nowadays many universities and superior education institutions around the country are teaching students at the B.Sc. level and postgraduate level many topics related to acoustics, such as Architectural Acoustics, Seismology, Mechanical Vibrations, Noise Control, Audio, Audiology, Music, etc. Also many institutions have started research programs in related fields, with participation of medical doctors, psychologists, musicians, engineers, etc. Details will be given on particular topics and development.

  5. An acoustic invisible gateway

    CERN Document Server

    Zhu, Yi-Fan; Liang, Bin; Kan, Wei-Wei; Yang, Jun; Cheng, Jian-Chun

    2015-01-01

    The recently-emerged concept of "invisible gateway" with the extraordinary capability to block the waves but allow the passage of other entities has attracted great attentions due to the general interests in illusion devices. However, the possibility to realize such a fascinating phenomenon for acoustic waves has not yet been explored, which should be of paramount significance for acoustical applications but would necessarily involve experimental difficulty. Here we design and experimentally demonstrate an acoustic invisible gateway (AIG) capable of concealing a channel under the detection of sound. Instead of "restoring" a whole block of background medium by using transformation acoustics that inevitably requires complementary or restoring media with extreme parameters, we propose an inherently distinct methodology that only aims at engineering the surface impedance at the "gate" to mimic a rigid "wall" and can be conveniently implemented by decorating meta-structures behind the channel. Such a simple yet ef...

  6. Principles of musical acoustics

    CERN Document Server

    Hartmann, William M

    2013-01-01

    Principles of Musical Acoustics focuses on the basic principles in the science and technology of music. Musical examples and specific musical instruments demonstrate the principles. The book begins with a study of vibrations and waves, in that order. These topics constitute the basic physical properties of sound, one of two pillars supporting the science of musical acoustics. The second pillar is the human element, the physiological and psychological aspects of acoustical science. The perceptual topics include loudness, pitch, tone color, and localization of sound. With these two pillars in place, it is possible to go in a variety of directions. The book treats in turn, the topics of room acoustics, audio both analog and digital, broadcasting, and speech. It ends with chapters on the traditional musical instruments, organized by family. The mathematical level of this book assumes that the reader is familiar with elementary algebra. Trigonometric functions, logarithms and powers also appear in the book, but co...

  7. Anal acoustic reflectometry

    DEFF Research Database (Denmark)

    Mitchell, Peter J; Klarskov, Niels; Telford, Karen J;

    2011-01-01

    Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis.......Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis....

  8. Acoustic surface cavitation

    OpenAIRE

    Zijlstra, Aaldert Geert

    2011-01-01

    Merely the presence of compressible entities, known as bubbles, greatly enriches the physical phenomena encountered when introducing ultrasound in a liquid. Mediated by the response of these bubbles, the otherwise diffuse and relatively low energy density of the acoustic field can induce strong, localized liquid motion, high internal temperatures and pressures as well as secondary acoustic emissions. In turn, these effects give rise to considerable stresses exerted on nearby objects and molec...

  9. Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.

    Science.gov (United States)

    Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A

    2014-01-01

    Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications. PMID:25418084

  10. Fish embryo multimodal imaging by laser Doppler digital holography

    CERN Document Server

    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.

  11. Analisis Efek Doppler pada Sistem Komunikasi ITS-Sat

    Directory of Open Access Journals (Sweden)

    Agriniwaty Paulus

    2013-09-01

    Full Text Available Analisa efek Doppler ini menggunakan pemrograman Matlab dengan citra yang berukuran 160 128 piksel, pada eksentrisitas (e satelit yang diasumsikan 0 sehingga bentuk lintasannya circular, dengan ketinggian 700 km dari stasiun bumi, sudut inklinasi sebesar 53° dan sinyal informasi ditransmisikan pada transmisi downlink dengan frekuensi carrier 2.4 GHz. Doppler shift terbesar terjadi saat satelit berada pada posisi terjauh dari terminal bumi yakni sebesar 51.077 KHz. Untuk  menghilangkan efek Doppler maka data output dikompensasi dengan invers dari efek Doppler tersebut. Berdasarkan hasil simulasi diperoleh bahwa BER untuk frekuensi Doppler maksimum maupun minimum adalah mendekati atau hampir sama yaitu 0.5001 dan 0.4998, dan dalam keadaan tanpa terkena Doppler shift yaitu ± 0.0197 untuk SNR 0 sampai 10 dB. Sedangkan dari segi kualitas citra, diperoleh bahwa untuk Doppler shift maksimum, kualitas citra lebih baik dibandingkan saat Doppler shift minimum.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-12-01

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

  13. Photoacoustic Doppler flow measurement in optically scattering media

    OpenAIRE

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V.

    2007-01-01

    We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microc...

  14. Rotational Doppler effect in left-handed materials

    OpenAIRE

    Luo, Hailu; Wen, Shuangchun; Shu, Weixing; Tang, Zhixiang; Zou, Yanhong; Fan, Dianyuan

    2008-01-01

    We explain the rotational Doppler effect associated with light beams carrying with orbital angular momentum in left-handed materials (LHMs). We demonstrate that the rotational Doppler effect in LHMs is unreversed, which is significantly different from the linear Doppler effect. The physics underlying this intriguing effect is the combined contributions of negative phase velocity and inverse screw of wave-front. In the normal dispersion region, the rotational Doppler effect induces a upstream ...

  15. Photoacoustic Doppler effect from flowing small light-absorbing particles.

    Science.gov (United States)

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V

    2007-11-01

    From the flow of a suspension of micrometer-scale carbon particles, the photoacoustic Doppler shift is observed. As predicted theoretically, the observed Doppler shift equals half of that in Doppler ultrasound and does not depend on the direction of laser illumination. This new physical phenomenon provides a basis for developing photoacoustic Doppler flowmetry, which can potentially be used for detecting fluid flow in optically scattering media and especially low-speed blood flow of relatively deep microcirculation in biological tissue.

  16. Applications of doppler effect in navigation and oceanography

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

    . The Doppler effect is also used in sports, through Doppler radar systems to measure ball speed. Navigation technology received a boost in the 1960s with the introduction of the satellite navigation system, which applies the Doppler effect. In this system...

  17. On acceleration dependence of Doppler effect in light

    Indian Academy of Sciences (India)

    Sanjay M Wagh

    2013-09-01

    Using only the geometric relationships of suitable locations, we analyse Doppler effect in light to show how the acceleration of the source also contributes to the Doppler shift. We further propose that an experiment be performed using cyclotron-type devices to determine the acceleration dependence of the Doppler shift.

  18. Solid breast neoplasms: Differential diagnosis with pulsed Doppler ultrasound

    NARCIS (Netherlands)

    T.J.A. Kuijpers (T. J A); A.I.M. Obdeijn (Inge-Marie); Ph.M. Kruyt (Philip); M. Oudkerk (Matthijs)

    1994-01-01

    textabstractIn this prospective study, duplex Doppler ultrasound was used in 95 consecutive patients with solid breast masses to evaluate the presence of neovascular flow. A positive Doppler signal, i.e., a Doppler shift frequency of more than 1 kHz using a 5 MHz insonating frequency, was found in 3

  19. 21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550... system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that combines the features of continuous wave doppler-effect technology with pulsed-echo effect technology and is intended...

  20. Equipment for flow measurements according to the ultrasonic Doppler method

    International Nuclear Information System (INIS)

    An instrument for flow measurements according to the ultrasonic Doppler method is described. It consists of an applicator with an ultrasonic oscillator and, connected to it, a Doppler instrument for the Doppler flow record. The angle of incidence of the ultrasonic beam may be taken into account, flow measurement independent of the angle thus becoming possible. (RW)

  1. Radar micro-doppler signatures processing and applications

    CERN Document Server

    Chen, Victor C; Miceli, William J

    2014-01-01

    Radar Micro-Doppler Signatures: Processing and applications concentrates on the processing and application of radar micro-Doppler signatures in real world situations, providing readers with a good working knowledge on a variety of applications of radar micro-Doppler signatures.

  2. Acoustic vector sensor signal processing

    Institute of Scientific and Technical Information of China (English)

    SUN Guiqing; LI Qihu; ZHANG Bin

    2006-01-01

    Acoustic vector sensor simultaneously, colocately and directly measures orthogonal components of particle velocity as well as pressure at single point in acoustic field so that is possible to improve performance of traditional underwater acoustic measurement devices or detection systems and extends new ideas for solving practical underwater acoustic engineering problems. Although acoustic vector sensor history of appearing in underwater acoustic area is no long, but with huge and potential military demands, acoustic vector sensor has strong development trend in last decade, it is evolving into a one of important underwater acoustic technology. Under this background, we try to review recent progress in study on acoustic vector sensor signal processing, such as signal detection, DOA estimation, beamforming, and so on.

  3. Range estimation by Doppler of multi-line in radiated noise spectrum

    Institute of Scientific and Technical Information of China (English)

    WU Guoqing; MA Li

    2005-01-01

    A method by applying Doppler frequency shift of multi-line in radiated noise spectrum to estimate the vertical range from a receiver to a moving vessel, which is supposed to move along a straight line at a constant velocity, is developed. This method is based on passive ranging by a single sensor and the depth of the sea and other environment parameters are not necessarily known. First the Wigner-Ville distribution is used as the instantaneous frequency estimator to find out the instantaneous frequencies of the muti-lines as a signal. Then define Doppler frequency shift basis functions, based on an algorithm called matching pursuit, by a searching strategy of variable span, and explore the minimum spatial distance between the signal and the Doppler frequency shift basis functions in a five-dimension space. The basis function of the obtained minimum spatial distance corresponds to the estimation of range and speed of the moving vessel. Computer simulations yield statistics errors in the range and speed estimates with differing intensities of noise. If the white noise deviation is less than 10% of the maximum Doppler frequency shift and time-window width is 1.47 times of reference-duration,relative error of range estimate is less than 5.4% and relative error of speed estimate is less than 1.4%. This estimation method has been tested and the result conforms to data collected during an experiment on the sea, the estimated speed is 52 knots and the estimated range is 42 m. The single point passive ranging method can be used for ranging purposes in sonar-buoys, mines,movement analysis of an underwater object in underwater acoustics experiment, and sound source level measurements.

  4. Extreme Value Analysis of Tidal Stream Velocity Perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Harding, Samuel; Thomson, Jim; Polagye, Brian; Richmond, Marshall C.; Durgesh, Vibhav; Bryden, Ian

    2011-04-26

    This paper presents a statistical extreme value analysis of maximum velocity perturbations from the mean flow speed in a tidal stream. This study was performed using tidal velocity data measured using both an Acoustic Doppler Velocimeter (ADV) and an Acoustic Doppler Current Profiler (ADCP) at the same location which allows for direct comparison of predictions. The extreme value analysis implements of a Peak-Over-Threshold method to explore the effect of perturbation length and time scale on the magnitude of a 50-year perturbation.

  5. Doppler Shift Compensation Schemes in VANETs

    Directory of Open Access Journals (Sweden)

    F. Nyongesa

    2015-01-01

    Full Text Available Over the last decade vehicle-to-vehicle (V2V communication has received a lot of attention as it is a crucial issue in intravehicle communication as well as in Intelligent Transportation System (ITS. In ITS the focus is placed on integration of communication between mobile and fixed infrastructure to execute road safety as well as nonsafety information dissemination. The safety application such as emergence alerts lays emphasis on low-latency packet delivery rate (PDR, whereas multimedia and infotainment call for high data rates at low bit error rate (BER. The nonsafety information includes multimedia streaming for traffic information and infotainment applications such as playing audio content, utilizing navigation for driving, and accessing Internet. A lot of vehicular ad hoc network (VANET research has focused on specific areas including channel multiplexing, antenna diversity, and Doppler shift compensation schemes in an attempt to optimize BER performance. Despite this effort few surveys have been conducted to highlight the state-of-the-art collection on Doppler shift compensation schemes. Driven by this cause we survey some of the recent research activities in Doppler shift compensation schemes and highlight challenges and solutions as a stock-taking exercise. Moreover, we present open issues to be further investigated in order to address the challenges of Doppler shift in VANETs.

  6. Doppler-ultralydundersøgelse af underekstremitetsarteriosklerose

    DEFF Research Database (Denmark)

    Rørdam, P; von Jessen, F; Sillesen, H H;

    1992-01-01

    Arteriography, which requires resources and is not entirely without risk, has hitherto been a prerequisite for reconstructive surgery in cases of symptom-producing arteriosclerosis in the lower limbs. As an alternative, indirect Doppler ultrasonic examination has been employed but does not appear...

  7. [Phlegmasia alba dolens diagnosed with Doppler ultrasonography].

    Science.gov (United States)

    Wulff, C; Lorentzen, T; Christensen, E; Pedersen, E B

    1996-11-11

    Differential diagnostic problems may occur in a patient with a cold, pale and swollen leg. Especially when the peripheral blood pressure is reduced, it is particularly difficult to distinguish cases caused by venous thrombosis from those caused by arterial embolism. Colour-Doppler ultra-sonography might be helpful for establishing the correct diagnosis. A case history is presented.

  8. Spectroscopic observation of the rotational Doppler effect.

    Science.gov (United States)

    Barreiro, S; Tabosa, J W R; Failache, H; Lezama, A

    2006-09-15

    We report on the first spectroscopic observation of the rotational Doppler shift associated with light beams carrying orbital angular momentum. The effect is evidenced as the broadening of a Hanle electromagnetically induced transparency coherence resonance on Rb vapor when the two incident Laguerre-Gaussian laser beams have opposite topological charges. The observations closely agree with theoretical predictions.

  9. Method for Canceling Ionospheric Doppler Effect

    Science.gov (United States)

    Vessot, R. F. C.

    1982-01-01

    Unified transponder system with hydrogen-maser oscillators at both stations can compensate for both motional and ionospheric components of Doppler shift. Appropriate choices of frequency shift in output of mixer m3. System exploits proportionality between dispersive component of frequency shift and reciprocal of frequency to achieve cancellation of dispersive component at output.

  10. Fifty Years of HF Doppler Observations

    OpenAIRE

    Ogawa, T.; T. Ichinose

    2009-01-01

    High frequency Doppler observations of the ionosphere began in August of 1957 in Kyoto. The number of the observation points worldwide were about 40 in 1980 and are about 20 at present. By this method the movement of the ionosphere reflection height and electron density below the height can be observed. Such variations are occurred by a wide variety of sources.

  11. Acoustic comfort in eating establishments

    DEFF Research Database (Denmark)

    Svensson, David; Jeong, Cheol-Ho; Brunskog, Jonas

    2014-01-01

    The subjective concept of acoustic comfort in eating establishments has been investigated in this study. The goal was to develop a predictive model for the acoustic comfort, by means of simple objective parameters, while also examining which other subjective acoustic parameters could help explain...... the feeling of acoustic comfort. Through several layers of anal ysis, acoustic comfort was found to be rather complex, and could not be explained entirely by common subjective parameters such as annoyance, intelligibility or privacy. A predictive model for the mean acoustic comfort for an eating establishment...

  12. Phononic crystals and acoustic metamaterials

    Directory of Open Access Journals (Sweden)

    Ming-Hui Lu

    2009-12-01

    Full Text Available Phononic crystals have been proposed about two decades ago and some important characteristics such as acoustic band structure and negative refraction have stimulated fundamental and practical studies in acoustic materials and devices since then. To carefully engineer a phononic crystal in an acoustic “atom” scale, acoustic metamaterials with their inherent deep subwavelength nature have triggered more exciting investigations on negative bulk modulus and/or negative mass density. Acoustic surface evanescent waves have also been recognized to play key roles to reach acoustic subwavelength imaging and enhanced transmission.

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

    Science.gov (United States)

    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. Doppler method leak detection for LMFBR steam generators. Pt. 2. Detection characteristics of bubble in-water using large scale SG model

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Hiromichi [Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab

    2000-06-01

    To prevent the expansion of tube damage and to maintain structural integrity in the steam generators (SGs) of a fast breeder reactor (FBR), it is necessary to detect precisely and immediately the leakage of water from heat transfer tubes. Therefore, an active acoustic method was developed. Previous studies have revealed that, in practical steam generators, the active acoustic method can detect bubbles of 10 l/s within 10 seconds. However to prevent the expansion of damage to neighboring tubes, it is necessary to detect smaller leakages of water from the heat transfer tubes. The Doppler method is designed to detect small leakages and to find the source of a leak before damage spreads to neighboring tubes. The detection sensitivity of the Doppler method and the influence of background noise were investigated experimentally. In-water experiments were performed using an SG full-sector model that simulates actual SGs. The results show that the Doppler method can detect bubbles of 0.1 l/s (equivalent to a water leak rate of about 0.1 g/s) within a few seconds and that the background noise has little effect on water leak detection performance. The Doppler method thus has great potential for the detection of water leakage in SGs. (author)

  15. Exact classical Doppler effect derived from the photon emission process

    CERN Document Server

    Lin, Chyi-Lung; Hsieh, Shang-Lin; Tsai, Chun-Ming

    2016-01-01

    The concept of photon is not necessary only applied to the relativistic Doppler theory. It may also work well for classical theory. As conservation of momentum and energy are physical laws, if applying these laws gives the exact relativistic Doppler effect, it should also give the exact classical Doppler effect. So far the classical Doppler effect is only obtained by using some approximation, as derived by Fermi in 1932. We show that the exact classical Doppler effect can be derived from the photon emission process in the exact treatment and reveal that these results are the same as those derived from the wave theory of light.

  16. The Multiple Doppler Radar Workshop, November 1979.

    Science.gov (United States)

    Carbone, R. E.; Harris, F. I.; Hildebrand, P. H.; Kropfli, R. A.; Miller, L. J.; Moninger, W.; Strauch, R. G.; Doviak, R. J.; Johnson, K. W.; Nelson, S. P.; Ray, P. S.; Gilet, M.

    1980-10-01

    The findings of the Multiple Doppler Radar Workshop are summarized by a series of six papers. Part I of this series briefly reviews the history of multiple Doppler experimentation, fundamental concepts of Doppler signal theory, and organization and objectives of the Workshop. Invited presentations by dynamicists and cloud physicists are also summarized.Experimental design and procedures (Part II) are shown to be of critical importance. Well-defined and limited experimental objectives are necessary in view of technological limitations. Specified radar scanning procedures that balance temporal and spatial resolution considerations are discussed in detail. Improved siting for suppression of ground clutter as well as scanning procedures to minimize errors at echo boundaries are discussed. The need for accelerated research using numerically simulated proxy data sets is emphasized.New technology to eliminate various sampling limitations is cited as an eventual solution to many current problems in Part III. Ground clutter contamination may be curtailed by means of full spectral processing, digital filters in real time, and/or variable pulse repetition frequency. Range and velocity ambiguities also may be minimized by various pulsing options as well as random phase transmission. Sidelobe contamination can be reduced through improvements in radomes, illumination patterns, and antenna feed types. Radar volume-scan time can be sharply reduced by means of wideband transmission, phased array antennas, multiple beam antennas, and frequency agility.Part IV deals with synthesis of data from several radars in the context of scientific requirements in cumulus clouds, widespread precipitation, and severe convective storms. The important temporal and spatial scales are examined together with the accuracy required for vertical air motion in each phenomenon. Factors that introduce errors in the vertical velocity field are identified and synthesis techniques are discussed separately for

  17. Wavefront Modulation and Subwavelength Diffractive Acoustics with an Acoustic Metasurface

    OpenAIRE

    Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A.

    2014-01-01

    Metasurfaces are a family of novel wavefront shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality as their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a desig...

  18. ACOUSTICS IN ARCHITECTURAL DESIGN, AN ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS.

    Science.gov (United States)

    DOELLE, LESLIE L.

    THE PURPOSE OF THIS ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS WAS--(1) TO COMPILE A CLASSIFIED BIBLIOGRAPHY, INCLUDING MOST OF THOSE PUBLICATIONS ON ARCHITECTURAL ACOUSTICS, PUBLISHED IN ENGLISH, FRENCH, AND GERMAN WHICH CAN SUPPLY A USEFUL AND UP-TO-DATE SOURCE OF INFORMATION FOR THOSE ENCOUNTERING ANY ARCHITECTURAL-ACOUSTIC DESIGN…

  19. ESTIMATION OF DOPPLER CENTROID FREQUENCY IN SPACEBORNE SCANSAR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Doppler centroid frequency is an essential parameter in the imaging processing of the Scanning mode Synthetic Aperture Radar(ScanSAR).Inaccurate Doppler centroid frequency will result in ghost images in imaging result.In this letter,the principle and algorithms of Doppler centroid frequency estimation are introduced.Then the echo data of ScanSAR system is analyzed.Based on the algorithms of energy balancing and correlation Doppler estimator in the estimation of Doppler centroid fequency in strip mode SAR,an improved method for Doppler centroid frequency estimation in ScanSAR is proposed.The method has improved the accuracy of Doppler centroid fequency estimation in ScanSAR by zero padding between burst data.Finally,the proposed method is validated with the processing of ENVironment SATellite Advanced Synthetic Aperture Radar(ENVISAT ASAR)wide swath raw data.

  20. Practical acoustic emission testing

    CERN Document Server

    2016-01-01

    This book is intended for non-destructive testing (NDT) technicians who want to learn practical acoustic emission testing based on level 1 of ISO 9712 (Non-destructive testing – Qualification and certification of personnel) criteria. The essential aspects of ISO/DIS 18436-6 (Condition monitoring and diagnostics of machines – Requirements for training and certification of personnel, Part 6: Acoustic Emission) are explained, and readers can deepen their understanding with the help of practice exercises. This work presents the guiding principles of acoustic emission measurement, signal processing, algorithms for source location, measurement devices, applicability of testing methods, and measurement cases to support not only researchers in this field but also and especially NDT technicians.

  1. Passive broadband acoustic thermometry

    Science.gov (United States)

    Anosov, A. A.; Belyaev, R. V.; Klin'shov, V. V.; Mansfel'd, A. D.; Subochev, P. V.

    2016-04-01

    The 1D internal (core) temperature profiles for the model object (plasticine) and the human hand are reconstructed using the passive acoustothermometric broadband probing data. Thermal acoustic radiation is detected by a broadband (0.8-3.5 MHz) acoustic radiometer. The temperature distribution is reconstructed using a priori information corresponding to the experimental conditions. The temperature distribution for the heated model object is assumed to be monotonic. For the hand, we assume that the temperature distribution satisfies the heat-conduction equation taking into account the blood flow. The average error of reconstruction determined for plasticine from the results of independent temperature measurements is 0.6 K for a measuring time of 25 s. The reconstructed value of the core temperature of the hand (36°C) generally corresponds to physiological data. The obtained results make it possible to use passive broadband acoustic probing for measuring the core temperatures in medical procedures associated with heating of human organism tissues.

  2. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

    Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...

  3. Acoustic detection of pneumothorax

    Science.gov (United States)

    Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.

    2003-04-01

    This study aims at investigating the feasibility of using low-frequency (pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (ppneumothorax states (pPneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (pPneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.

  4. A Century of Acoustic Metrology

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1998-01-01

    The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect.......The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect....

  5. Advanced Active Acoustics Lab (AAAL)

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Active Acoustics Lab (AAAL) is a state-of-the-art Undersea Warfare (USW) acoustic data analysis facility capable of both active and passive underwater...

  6. Densitometry By Acoustic Levitation

    Science.gov (United States)

    Trinh, Eugene H.

    1989-01-01

    "Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.

  7. Acoustic classification of dwellings

    DEFF Research Database (Denmark)

    Berardi, Umberto; Rasmussen, Birgit

    2014-01-01

    insulation performance, national schemes for sound classification of dwellings have been developed in several European countries. These schemes define acoustic classes according to different levels of sound insulation. Due to the lack of coordination among countries, a significant diversity in terms...... of descriptors, number of classes, and class intervals occurred between national schemes. However, a proposal “acoustic classification scheme for dwellings” has been developed recently in the European COST Action TU0901 with 32 member countries. This proposal has been accepted as an ISO work item. This paper...

  8. Strong acoustic wave action

    Science.gov (United States)

    Gokhberg, M. B.

    1983-07-01

    Experiments devoted to acoustic action on the atmosphere-magnetosphere-ionosphere system using ground based strong explosions are reviewed. The propagation of acoustic waves was observed by ground observations over 2000 km in horizontal direction and to an altitude of 200 km. Magnetic variations up to 100 nT were detected by ARIEL-3 satellite near the epicenter of the explosion connected with the formation of strong field aligned currents in the magnetosphere. The enhancement of VLF emission at 800 km altitude is observed.

  9. Structural Acoustics and Vibrations

    Science.gov (United States)

    Chaigne, Antoine

    This structural chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

  10. Variable-Position Acoustic Levitation

    Science.gov (United States)

    Barmatz, M. B.; Stoneburner, J. D.; Jacobi, N.; Wang, T. G.

    1983-01-01

    Method of acoustic levitation supports objects at positions other than acoustic nodes. Acoustic force is varied so it balances gravitational (or other) force, thereby maintaining object at any position within equilibrium range. Levitation method applicable to containerless processing. Such objects as table-tennis balls, hollow plastic spheres, and balsa-wood spheres levitated in laboratory by new method.

  11. Two classes of medium-scale traveling ionospheric disturbances observed with an array on HF-Doppler sounders

    International Nuclear Information System (INIS)

    The importance of the quasi-evanescent mode of acoustic-gravity waves (AGW) was recently stressed to elaborate on the daytime dispersion characteristics of horizontal velocity of medium-scale traveling ionospheric disturbances (MS-TID) which were observed by a high frequency Doppler (HFD) sounder array in central Japan. Observed MS-TIDs were classified into two categories: the internal mode and the quasi-evanescent mode as regards physical implication. Nonlinear wave-wave interaction is proposed in an attempt to explain salient features of the latter-class TID

  12. Two classes of medium-scale traveling ionospheric disturbances observed with an array on HF-Doppler sounders

    Science.gov (United States)

    Shibata, T.; Okuzawa, T.

    1985-01-01

    The importance of the quasi-evanescent mode of acoustic-gravity waves (AGW) was recently stressed to elaborate on the daytime dispersion characteristics of horizontal velocity of medium-scale traveling ionospheric disturbances (MS-TID) which were observed by a high frequency Doppler (HFD) sounder array in central Japan. Observed MS-TIDs were classified into two categories: the internal mode and the quasi-evanescent mode as regards physical implication. Nonlinear wave-wave interaction is proposed in an attempt to explain salient features of the latter-class TID.

  13. Spatial and Wavenumber Resolution of Doppler Reflectometry

    CERN Document Server

    Surkov, A; Surkov, Alexander; Gusakov, Evgeniy

    2004-01-01

    Doppler reflectometry spatial and wavenumber resolution is analyzed within the framework of the linear Born approximation in slab plasma model. Explicit expression for its signal backscattering spectrum is obtained in terms of wavenumber and frequency spectra of turbulence which is assumed to be radially statistically inhomogeneous. Scattering efficiency for both back and forward scattering (in radial direction) is introduced and shown to be inverse proportional to the square of radial wavenumber of the probing wave at the fluctuation location thus making the spatial resolution of diagnostics sensitive to density profile. It is shown that in case of forward scattering additional localization can be provided by the antenna diagram. It is demonstrated that in case of backscattering the spatial resolution can be better if the turbulence spectrum at high radial wavenumbers is suppressed. The improvement of Doppler reflectometry data localization by probing beam focusing onto the cut-off is proposed and described....

  14. Minior Actinide Doppler Coefficient Measurement Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Nolan E. Hertel; Dwayne Blaylock

    2008-04-10

    The "Minor Actinide Doppler Coefficient Measurement Assessment" was a Department of Energy (DOE) U-NERI funded project intended to assess the viability of using either the FLATTOP or the COMET critical assembly to measure high temperature Doppler coefficients. The goal of the project was to calculate using the MCNP5 code the gram amounts of Np-237, Pu-238, Pu-239, Pu-241, AM-241, AM-242m, Am-243, and CM-244 needed to produce a 1E-5 in reactivity for a change in operating temperature 800C to 1000C. After determining the viability of using the assemblies and calculating the amounts of each actinide an experiment will be designed to verify the calculated results. The calculations and any doncuted experiments are designed to support the Advanced Fuel Cycle Initiative in conducting safety analysis of advanced fast reactor or acceoerator-driven transmutation systems with fuel containing high minor actinide content.

  15. Color Doppler US of the penis

    Energy Technology Data Exchange (ETDEWEB)

    Bertolotto, Michele (ed.) [Trieste Univ. Ospedale di Cattinara (Italy). Dept. Radiology

    2008-07-01

    This book provides a comprehensive reference and practical guide on the application of US to penile diseases and conditions. After introductory chapters on technical requirements and penile anatomy, subsequent chapters offer a systematic overview of the diverse applications of color Doppler US. The topics covered include erectile dysfunction, Peyronie's disease, priapism, trauma, tumors, the postoperative penis, inflammation, and fibrosis. Each topic is introduced by a clinical overview with the purpose of clarifying the problems and elucidating what the urologist may expect from color Doppler US. Thereafter, performance of the US study is explained and the pathological anatomy reviewed. High-quality images obtained with high-end US equipment are included. Each chapter also contains a section on the diagnostic information provided by other imaging modalities, and in particular MRI. (orig.)

  16. Laser Doppler measurement of cutaneous blood flow

    International Nuclear Information System (INIS)

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

  17. Transcranial Doppler sonography in familial hemiplegic migraine

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-02-01

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

  18. Design of a Doppler reflectometer for KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K. D., E-mail: kdlee@nfri.re.kr; Nam, Y. U.; Seo, Seong-Heon; Kim, Y. S. [National Fusion Research Institute, Yuseong, Daejeon 305-333 (Korea, Republic of)

    2014-11-15

    A Doppler reflectometer has been designed to measure the poloidal propagation velocity on the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. It has the operating frequency range of V-band (50-75 GHz) and the monostatic antenna configuration with extraordinary mode (X-mode). The single sideband modulation with an intermediate frequency of 50 MHz is used for the heterodyne measurement with the 200 MHz in-phase and quadrature (I/Q) phase detector. The corrugated conical horn antenna is used to approximate the Gaussian beam propagation and it is installed together with the oversized rectangular waveguides in the vacuum vessel. The first commissioning test of the Doppler reflectometer system on the KSTAR tokamak is planned in the 2014 KSTAR experimental campaign.

  19. Renal duplex Doppler ultrasound findings in diabetics

    International Nuclear Information System (INIS)

    The correlation between clinical-laboratory findings and renal duplex Doppler ultrasound findings was studied in 45 patients with diabetes mellitus to see the role of duplex Doppler ultrasound in the detection of diabetic nephropathy. The resistive indices in patients with elevated serum creatinine, BUN, proteinuria, and systolic blood pressure levels were statistically significantly higher than those in patients with normal levels (p<0.05). Also resistive indics in patients with retinopathy were higher than that in patients without retinopathy (p<0.05). But the ultrasound morphologic changes of kidney such as renal length, cortical eye-catching, and corticomedullarycontrast were not well correlated with clinical-laboratory data and resistive index. The resistive index of the kidney in conjunction with clinical-laboratory data in diabetics may be helpful in the evaluation of diabetic nephropathy

  20. Colour Doppler ultrasound of the penis

    Energy Technology Data Exchange (ETDEWEB)

    Wilkins, C.J.; Sriprasad, S.; Sidhu, P.S. E-mail: paulsidhu@compuserve.com

    2003-07-01

    Because it is a superficial structure, the penis is ideally suited to ultrasound imaging. A number of disease processes, including Peyronie's disease, penile fractures and penile tumours, are clearly visualized with ultrasound. An assessment of priapism can also be made using spectral Doppler waveform technology. Furthermore, dynamic assessment of cavernosal arterial changes after pharmaco-stimulation allows diagnosis of arterial and venogenic causes for impotence. This pictorial review illustrates the range of diseases encountered with ultrasound of the penis.

  1. Color Doppler imaging of cervicocephalic fibromuscular dysplasia

    OpenAIRE

    Grzyska Ulrich; Arning Christian

    2004-01-01

    Abstract Background Fibromuscular dysplasia (FMD) is a possible cause of stroke, especially in middle-aged women. However, only few reports are available on ultrasonographic detection and monitoring. Methods Among the 15,000 patients who underwent color Doppler imaging (CDI) of the cervicocephalic arteries during the study period, all cases fulfilling ultrasound criteria of FMD were included into the case series. Criteria of FMD were: 1. Segmental string-of-beads pattern, 2. Localization in t...

  2. Sub-Nyquist Radar via Doppler Focusing

    OpenAIRE

    Bar-Ilan, Omer; Eldar, Yonina C.

    2012-01-01

    We investigate the problem of a monostatic pulse-Doppler radar transceiver trying to detect targets, sparsely populated in the radar's unambiguous time-frequency region. Several past works employ compressed sensing (CS) algorithms to this type of problem, but either do not address sample rate reduction, impose constraints on the radar transmitter, propose CS recovery methods with prohibitive dictionary size, or perform poorly in noisy conditions. Here we describe a sub-Nyquist sampling and re...

  3. Doppler cooling to the Quantum limit

    OpenAIRE

    Chalony, Maryvonne; Kastberg, Anders; Klappauf, Bruce; Wilkowski, David

    2011-01-01

    Doppler cooling on a narrow transition is limited by the noise of single scattering events. It shows novel features, which are in sharp contrast with cooling on a broad transition, such as a non-Gaussian momentum distribution, and divergence of its mean square value close to the resonance. We have observed those features using 1D cooling on an intercombination transition in strontium, and compared the measurements with theoretical predictions and Monte Carlo simulations. We also find that for...

  4. Doppler Lidar Wind Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

    Wind speed and direction, together with pressure, temperature, and relative humidity, are the most fundamental atmospheric state parameters. Accurate measurement of these parameters is crucial for numerical weather prediction. Vertically resolved wind measurements in the atmospheric boundary layer are particularly important for modeling pollutant and aerosol transport. Raw data from a scanning coherent Doppler lidar system can be processed to generate accurate height-resolved measurements of wind speed and direction in the atmospheric boundary layer.

  5. Doppler Findings in Intrapartum Fetal Distress

    OpenAIRE

    Khatereh Tooba; Laleh Eslamian

    2011-01-01

    The umbilical vein (UV) has a non pulsating and even pattern in normal fetuses. Pulsation of UV has been described in severely growth restricted fetuses with chronic hypoxia. We wanted to see whether UV pulsations could also be seen in fetuses with heart deceleration during labor, as an adjunctive measure to assess the intra partum hypoxia. In a prospective study Doppler examination was performed on 34 fetuses with normal cardiotocography (CGT) and 26 fetuses with abnormal CTGs (GA>37w and ce...

  6. From Architectural Acoustics to Acoustical Architecture Using Computer Simulation

    DEFF Research Database (Denmark)

    Schmidt, Anne Marie Due; Kirkegaard, Poul Henning

    2005-01-01

    Architectural acoustics design has in the past been based on simple design rules. However, with a growing complexity in architectural acoustics and the emergence of room acoustic simulation programmes with considerable potential, it is now possible to subjectively analyse and evaluate acoustic...... properties prior to the actual construction of a building. With the right tools applied, acoustic design can become an integral part of the architectural design process. The aim of this paper is to investigate the field of application that an acoustic simulation programme can have during an architectural...... acoustic design process and to set up a strategy to develop future programmes. The emphasis is put on the first three out of four phases in the working process of the architect and a case study is carried out in which each phase is represented by typical results ? as exemplified with reference...

  7. COLOUR DOPPLER EVALUATION OF ACUTE RENAL COLIC

    Directory of Open Access Journals (Sweden)

    Vallepu Ramaiah

    2016-05-01

    Full Text Available AIMS Can Doppler index–RI be a predictor of renal colics impending obstruction in acute and emergency clinical settings. To compare the results of RI in cases of obstructive, nondilated and normal kidneys. METHODS A total of 90 patients were included in this prospective study. The patients were grouped into three categories based on the clinical settings. Group 1 with acute unilateral obstruction were 44, group 2 who were presented with flank pain without stone disease were 26 and group 3 were 20 patients with sonologically normal kidneys. Grey scale ultrasonography and colour Doppler study carried out in all the groups and index – RI value were compared. RESULTS The study showed differences in RI values among the groups (0.726±0.04, 0.63±0.039 and 0.608±0.03 respectively. CONCLUSION In acute and emergency clinical setting, grey scale ultrasonography and interrogation with colour Doppler index– RI improved the assessment and detection of impending obstructive uropathy.

  8. Doppler Lidar for Wind Measurements on Venus

    Science.gov (United States)

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

    2010-01-01

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

  9. Underwater Acoustic Networking Techniques

    CERN Document Server

    Otnes, Roald; Casari, Paolo; Goetz, Michael; Husøy, Thor; Nissen, Ivor; Rimstad, Knut; van Walree, Paul; Zorzi, Michele

    2012-01-01

    This literature study presents an overview of underwater acoustic networking. It provides a background and describes the state of the art of all networking facets that are relevant for underwater applications. This report serves both as an introduction to the subject and as a summary of existing protocols, providing support and inspiration for the development of network architectures.

  10. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J;

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...

  11. Surface Acoustic Wave Devices

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...

  12. Portable acoustic myography

    DEFF Research Database (Denmark)

    Harrison, Adrian Paul; Danneskiold-Samsøe, Bente; Bartels, Else Marie

    2013-01-01

    Muscle sound gives a local picture of muscles involved in a particular movement and is independent of electrical signals between nerve and muscle. Sound recording (acoustic myography) is a well-known noninvasive technique that has suffered from not being easily applicable, as well as not being ab...

  13. Multi-carrier Communications over Time-varying Acoustic Channels

    Science.gov (United States)

    Aval, Yashar M.

    Acoustic communication is an enabling technology for many autonomous undersea systems, such as those used for ocean monitoring, offshore oil and gas industry, aquaculture, or port security. There are three main challenges in achieving reliable high-rate underwater communication: the bandwidth of acoustic channels is extremely limited, the propagation delays are long, and the Doppler distortions are more pronounced than those found in wireless radio channels. In this dissertation we focus on assessing the fundamental limitations of acoustic communication, and designing efficient signal processing methods that cam overcome these limitations. We address the fundamental question of acoustic channel capacity (achievable rate) for single-input-multi-output (SIMO) acoustic channels using a per-path Rician fading model, and focusing on two scenarios: narrowband channels where the channel statistics can be approximated as frequency- independent, and wideband channels where the nominal path loss is frequency-dependent. In each scenario, we compare several candidate power allocation techniques, and show that assigning uniform power across all frequencies for the first scenario, and assigning uniform power across a selected frequency-band for the second scenario, are the best practical choices in most cases, because the long propagation delay renders the feedback information outdated for power allocation based on the estimated channel response. We quantify our results using the channel information extracted form the 2010 Mobile Acoustic Communications Experiment (MACE'10). Next, we focus on achieving reliable high-rate communication over underwater acoustic channels. Specifically, we investigate orthogonal frequency division multiplexing (OFDM) as the state-of-the-art technique for dealing with frequency-selective multipath channels, and propose a class of methods that compensate for the time-variation of the underwater acoustic channel. These methods are based on multiple

  14. The Doppler effect is not what you think it is: dramatic pitch change due to dynamic intensity change.

    Science.gov (United States)

    McBeath, Michael K; Neuhoff, John G

    2002-06-01

    Historically, auditory pitch has been considered to be a function of acoustic frequency, with only a small effect being due to absolute intensity. Yet we found that when tones are Doppler shifted so that frequency drops, the pitch dramatically rises and falls, closely following the pattern of dynamic intensity change. We show that continuous intensity change can produce pitch variation comparable to a frequency change approaching an octave. This effect opposes and is an order of magnitude larger than the well-known effect of discrete intensity change in the frequency range employed. We propose that the perceptual interaction of continuous changes in pitch and loudness reflects a natural correlation between changes in frequency and intensity that is neurally encoded to facilitate the parsing and processing of meaningful acoustic patterns.

  15. Holograms for acoustics

    Science.gov (United States)

    Melde, Kai; Mark, Andrew G.; Qiu, Tian; Fischer, Peer

    2016-09-01

    Holographic techniques are fundamental to applications such as volumetric displays, high-density data storage and optical tweezers that require spatial control of intricate optical or acoustic fields within a three-dimensional volume. The basis of holography is spatial storage of the phase and/or amplitude profile of the desired wavefront in a manner that allows that wavefront to be reconstructed by interference when the hologram is illuminated with a suitable coherent source. Modern computer-generated holography skips the process of recording a hologram from a physical scene, and instead calculates the required phase profile before rendering it for reconstruction. In ultrasound applications, the phase profile is typically generated by discrete and independently driven ultrasound sources; however, these can only be used in small numbers, which limits the complexity or degrees of freedom that can be attained in the wavefront. Here we introduce monolithic acoustic holograms, which can reconstruct diffraction-limited acoustic pressure fields and thus arbitrary ultrasound beams. We use rapid fabrication to craft the holograms and achieve reconstruction degrees of freedom two orders of magnitude higher than commercial phased array sources. The technique is inexpensive, appropriate for both transmission and reflection elements, and scales well to higher information content, larger aperture size and higher power. The complex three-dimensional pressure and phase distributions produced by these acoustic holograms allow us to demonstrate new approaches to controlled ultrasonic manipulation of solids in water, and of liquids and solids in air. We expect that acoustic holograms will enable new capabilities in beam-steering and the contactless transfer of power, improve medical imaging, and drive new applications of ultrasound.

  16. Controlling sound with acoustic metamaterials

    DEFF Research Database (Denmark)

    Cummer, Steven A. ; Christensen, Johan; Alù, Andrea

    2016-01-01

    Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales....... The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak objects from incident acoustic energy. Active acoustic metamaterials use external control to create......-scale metamaterial structures and converting laboratory experiments into useful devices. In this Review, we outline the designs and properties of materials with unusual acoustic parameters (for example, negative refractive index), discuss examples of extreme manipulation of sound and, finally, provide an overview...

  17. Assessment of a direct acoustic cochlear stimulator.

    Science.gov (United States)

    Chatzimichalis, Michail; Sim, Jae Hoon; Huber, Alexander M

    2012-01-01

    This study aimed to assess the functional results of a new, active, acoustic-mechanical hearing implant, the Direct Acoustic Cochlear Stimulation Partial Implant (DACS PI), in a preclinical study. The DACS PI is an electromagnetic device fixed to the mastoid by screws and coupled to a standard stapes prosthesis by an artificial incus (AI). The function of the DACS PI-aided reconstruction was assessed by determining: (1) the maximum equivalent sound pressure level (SPL) of the implant, which was obtained from measurements of the volume displacement at the round window in normal and implanted ears, and (2) the quality at the coupling interface between the AI of the DACS and the stapes prosthesis, which was quantified from measurements of relative motions between the AI and the prosthesis. Both measurements were performed with fresh temporal bones using a scanning laser Doppler interferometry system. The expected maximum equivalent SPL with a typical driving voltage of 0.3 V was about 115-125 dB SPL up to 1.5 kHz in reconstruction with the DACS PI, and decreased with a roll-off slope of about 65 dB/decade, reaching 90 dB SPL at 8 kHz. The large roll-off relative to a normal ear was presumed to be a relatively high inductive impedance of the coil of the DACS PI actuator at higher frequencies. Good coupling quality between the AI and the prosthesis was achieved below the resonance (∼1.5 kHz) of the DACS PI for all tested stapes prostheses. Above the resonance, the SMart Piston, which is composed of a shape-memory alloy, had the best coupling quality.

  18. Myocardial Strain and Strain Rate Imaging: Comparison between Doppler Derived Strain Imaging and Speckle Tracking Echocardiography

    Directory of Open Access Journals (Sweden)

    Anita Sadeghpour

    2013-05-01

    Full Text Available Regional myocardial function has been traditionally assessed by visual estimation (1. Echocardiographic strain imaging which is known as deformation imaging, has been emerged as a quantitative technique to accurately estimate regional myocardial function and contractility. Currently, strain imaging has been regarded as a research tool in the most echocardiography laboratories. However, in recent years, strain imaging has gain momentum in daily clinical practice (2. The following two techniques have dominated the research arena of echocardiography: (1 Doppler based tissue velocity measurements, frequently referred to tissue Doppler or myocardial Doppler, and (2 speckle tracking on the basis of displacement measurements (3. Over the past two decades, Tissue Doppler Imaging (TDI and Doppler –derived strain (S and strain rate (SR imaging were introduced to quantify regional myocardial function. However, Doppler–derived strain variables faced criticisms, with regard to the angle dependency, noise interference, and substantial intraobserver and interobserver variability. The angle dependency is the major weakness of Doppler based methodology; however, it has the advantage of online measurements of velocities and time intervals with excellent temporal resolution, which is essential for the assessment of ischemia (4. Speckle-tracking echocardiography (STE or Non Doppler 2D strain echocardiography is a relatively new, largely angle-independent technique that analyzes motion by tracking natural acoustic reflections and interference patterns within an ultrasonic window. The image-processing algorithm tracks elements with approximately 20 to 40 pixels containing stable patterns and are described as ‘‘speckles’’ or ‘‘fingerprints’’. The speckles seen in grayscale B-mode (2D images are tracked consecutively frame to frame (5, 6. Assessment of 2D strain by STE is a semiautomatic method that requires definition of the myocardium

  19. Doppler effect in resonant photoemission from SF6: correlation between Doppler profile and Auger emission anisotropy.

    Science.gov (United States)

    Kitajima, M; Ueda, K; De Fanis, A; Furuta, T; Shindo, H; Tanaka, H; Okada, K; Feifel, R; Sorensen, S L; Gel'mukhanov, F; Baev, A; Agren, H

    2003-11-21

    Fragmentation of the SF6 molecule upon F 1s excitation has been studied by resonant photoemission. The F atomiclike Auger line exhibits the characteristic Doppler profile that depends on the direction of the photoelectron momentum relative to the polarization vector of the radiation as well as on the photon energy. The measured Doppler profiles are analyzed by the model simulation that takes account of the anisotropy of the Auger emission in the molecular frame. The Auger anisotropy extracted from the data decreases with an increase in the F-SF5 internuclear distance.

  20. Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin

    CERN Document Server

    Darquié, Benoît; Sow, Papa Lat Tabara; Lemarchand, Cyril; Triki, Meriam; Tokunaga, Sean; Bordé, Christian J; Chardonnet, Christian; Daussy, Christophe

    2015-01-01

    Accurate molecular spectroscopy in the mid-infrared region allows precision measurements of fundamental constants. For instance, measuring the linewidth of an isolated Doppler-broadened absorption line of ammonia around 10 $\\mu$m enables a determination of the Boltzmann constant k B. We report on our latest measurements. By fitting this lineshape to several models which include Dicke narrowing or speed-dependent collisional effects, we find that a determination of k B with an uncertainty of a few ppm is reachable. This is comparable to the best current uncertainty obtained using acoustic methods and would make a significant contribution to any new value of k B determined by the CODATA. Furthermore, having multiple independent measurements at these accuracies opens the possibility of defining the kelvin by fixing k B, an exciting prospect considering the upcoming redefinition of the International System of Units.

  1. Modelling Solar Oscillation Power Spectra: II. Parametric Model of Spectral Lines Observed in Doppler Velocity Measurements

    CERN Document Server

    Vorontsov, Sergei V

    2013-01-01

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

  2. Acoustic hemostasis device for automated treatment of bleeding in limbs

    Science.gov (United States)

    Sekins, K. Michael; Zeng, Xiaozheng; Barnes, Stephen; Hopple, Jerry; Kook, John; Moreau-Gobard, Romain; Hsu, Stephen; Ahiekpor-Dravi, Alexis; Lee, Chi-Yin; Ramachandran, Suresh; Maleke, Caroline; Eaton, John; Wong, Keith; Keneman, Scott

    2012-10-01

    A research prototype automated image-guided acoustic hemostasis system for treatment of deep bleeding was developed and tested in limb phantoms. The system incorporated a flexible, conformal acoustic applicator cuff. Electronically steered and focused therapeutic arrays (Tx) populated the cuff to enable dosing from multiple Tx's simultaneously. Similarly, multiple imaging arrays (Ix) were deployed on the cuff to enable 3D compounded images for targeting and treatment monitoring. To affect a lightweight cuff, highly integrated Tx electrical circuitry was implemented, fabric and lightweight structural materials were used, and components were minimized. Novel cuff and Ix and Tx mechanical registration approaches were used to insure targeting accuracy. Two-step automation was implemented: 1) targeting (3D image volume acquisition and stitching, Power and Pulsed Wave Doppler automated bleeder detection, identification of bone, followed by closed-loop iterative Tx beam targeting), and 2) automated dosing (auto-selection of arrays and Tx dosing parameters, power initiation and then monitoring by acoustic thermometry for power shut-off). In final testing the device automatically detected 65% of all bleeders (with various bleeder flow rates). Accurate targeting was achieved in HIFU phantoms with end-dose (30 sec) temperature rise reaching the desired 33-58°C. Automated closed-loop targeting and treatment was demonstrated in separate phantoms.

  3. Influence of Doppler Bin Width on GNSS Detection Probabilities

    CERN Document Server

    Geiger, Bernhard C

    2011-01-01

    The acquisition stage in GNSS receivers determines Doppler shifts and code phases of visible satellites. Acquisition is thus a search in two continuous dimensions, where the digital algorithms require a partitioning of the search space into cells. We present analytic expressions for the acquisition performance depending on the partitioning of the Doppler frequency domain. In particular, the impact of the number and width of Doppler bins is analyzed. The presented results are verified by simulations.

  4. Applications of Doppler ultrasound in clinical vascular disease

    Science.gov (United States)

    Barnes, R. W.; Hokanson, D. E.; Sumner, D. S.; Strandness, D. E., Jr.

    1975-01-01

    Doppler ultrasound has become the most useful and versatile noninvasive technique for objective evaluation of clinical vascular disease. Commercially available continuous-wave instruments provide qualitative and quantitative assessment of venous and arterial disease. Pulsed Doppler ultrasound was developed to provide longitudinal and transverse cross-sectional images of the arterial lumen with a resolution approaching that of conventional X-ray techniques. Application of Doppler ultrasound in venous, peripheral arterial, and cerebrovascular diseases is reviewed.

  5. Analysis on rotational Doppler Effect based on modal expansion method

    CERN Document Server

    Zhou, Hailong; Zhang, Pei; Zhang, Xinliang

    2015-01-01

    We theoretically investigate the optical rotational Doppler Effect using modal expansion method. We find that the frequency shift content is only determined by the surface of spinning object and the reduced Doppler shift is linear to the change of mode index. The theoretical model makes us better understand the physical processes of rotational Doppler Effect. It can provide theoretical guidance for many related applications, such as detection of rotating bodies, detection of OAM and frequency shift.

  6. Ionospheric Doppler measurements by means of HF-radar techniques

    OpenAIRE

    D. Altadill; Bianchi, C

    2005-01-01

    Studies of the dynamics of the ionosphere and its related phenomena are mainly based on Doppler Drift measurements. The time variation (ionisation/recombination) of plasma density, thermospheric wind and others can be observed by means of HF-radars. The technique of Doppler Drift measurements is a quite complex technique that is now affordable by means of an advanced ionospheric sounder. The combination of vertical sounding and interferometric Doppler detection discloses the Doppl...

  7. Evaluating Peripheral Vascular Injuries: Is Color Doppler Enough for Diagnosis?

    Directory of Open Access Journals (Sweden)

    Mohd Lateef Wani

    2014-03-01

    Full Text Available Background:: Vascular injury poses a serious threat to limb and life. Thus, diagnosis should be made immediately with minimally invasive methods. Doppler is a good aid in diagnosis of vascular injury. Methods:: The present prospective study was conducted on 150 patients who presented with soft signs (the signs which are suggestive but not confirmatory of vascular injury. They were subjected to color Doppler examination before exploration. The patients with the features of vascular injury on color Doppler were subjected to exploration. On the other hand, those who had normal Doppler were subjected to CT- angiography. Then, the findings of the exploration were matched with those of color Doppler. The data were analyzed using the SPSS statistical software. Results:: Out of the 150 Doppler examinations, 110 (73.33% were reported as positive, while 40 were reported as negative for vascular injury. These were subjected to CT-angiography and seven of them had the features of vascular injury on CT-angiography. All the patients with positive Doppler or CT angiography findings were subjected to exploration. Doppler had a sensitivity of 94% and specificity of 82.5% in diagnosis of vascular injury using Binary classification test. Conclusions:: Color Doppler is an easily available, reliable, and handy method of diagnosing a vascular injury. It has a very high sensitivity and specificity in diagnosis of vascular injuries.

  8. Eliminating Doppler Effects in Synthetic-Aperture Radar Optical Processors

    Science.gov (United States)

    Constantindes, N. J.; Bicknell, T. J.

    1984-01-01

    Pair of photodetectors generates correction signals. Instrument detects Doppler shifts in radar and corrects processing parameters so ambiguities caused by shifts not manifested as double or overlapping images.

  9. Reexamination of the Doppler effect through Maxwell's equations.

    Science.gov (United States)

    Guo, Wei; Aktas, Yildirim

    2012-08-01

    In this work, the electric field emitted from a moving source, an electric point dipole, is analyzed for the purpose of illustrating the physics behind the Doppler effect. It is found that if the (translational) motion of the source is nonrelativistic, the Doppler effect is realized in two steps: the motion of the source first causes the dyadic Green function associated with the electric field to acquire an oscillation frequency in the far-field region of the source, and then the frequency leads to the Doppler effect. It is also demonstrated that the Doppler effect is observable only in the far-field region of the source.

  10. EUV Doppler Imaging for CubeSat Platforms Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mature the design and fabricate the Flare Initiation Doppler Imager (FIDI) instrument to demonstrate low-spacecraft-resource EUV technology (most notably,...

  11. Flat acoustic lens by acoustic grating with curled slits

    KAUST Repository

    Peng, Pai

    2014-10-01

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry-Perot resonance.

  12. Acoustic energy harvesting based on a planar acoustic metamaterial

    Science.gov (United States)

    Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine

    2016-06-01

    We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.

  13. Burst Format Design for Optimum Joint Estimation of Doppler-Shift and Doppler-Rate in Packet Satellite Communications

    Directory of Open Access Journals (Sweden)

    Luca Giugno

    2007-05-01

    Full Text Available This paper considers the problem of optimizing the burst format of packet transmission to perform enhanced-accuracy estimation of Doppler-shift and Doppler-rate of the carrier of the received signal, due to relative motion between the transmitter and the receiver. Two novel burst formats that minimize the Doppler-shift and the Doppler-rate Cramér-Rao bounds (CRBs for the joint estimation of carrier phase/Doppler-shift and of the Doppler-rate are derived, and a data-aided (DA estimation algorithm suitable for each optimal burst format is presented. Performance of the newly derived estimators is evaluated by analysis and by simulation, showing that such algorithms attain their relevant CRBs with very low complexity, so that they can be directly embedded into new-generation digital modems for satellite communications at low SNR.

  14. A joint synchronization parameter estimation in fractional Fourier transform orthogonal frequency division multiplexing underwater acoustic communication system

    Directory of Open Access Journals (Sweden)

    Jia-chun Zheng

    2016-03-01

    Full Text Available In the conditions of Gaussian noise, symmetric alpha stable impulse noise, multipath propagation, Doppler effect, and so on, a joint synchronization algorithm is proposed for underwater acoustic communication system based on fractional Fourier transform orthogonal frequency division multiplexing. The algorithm realizes the orthogonal multicarrier underwater acoustic communication system synchronization based on that the symmetrical triangular linear frequency modulation signal has the energy convergence in the domain of fractional Fourier transform. In order to verify the effectiveness of the algorithm, hyperbolic frequency modulation signal and linear frequency modulation signal are used as the evaluation index, and the synchronization performance of bit error rate of them is compared by simulation and pool experiments. The simulation results show that the proposed algorithm in this article is resistant to Gaussian noise, symmetric alpha stable pulse noise, multipath propagation, and Doppler effect, compared with traditional synchronization algorithms; the synchronization error probability is low at the same signal-to-noise ratio.

  15. Linking the thermodynamic temperature to an optical frequency: recent advances in Doppler broadening thermometry

    Science.gov (United States)

    2016-01-01

    Laser spectroscopy in the linear regime of radiation–matter interaction is a powerful tool for measuring thermodynamic quantities in a gas at thermodynamic equilibrium. In particular, the Doppler effect can be considered a gift of nature, linking the thermal energy to an optical frequency, namely the line centre frequency of an atomic or molecular spectral line. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry (DBT). This paper reports on the efforts that have been carried out, in the last decade, worldwide, to the end of making DBT competitive with more consolidated and accurate methodologies, such as acoustic gas thermometry and dielectric constant gas thermometry. The main requirements for low-uncertainty DBT, of both theoretical and technical nature, will be discussed, with a special focus on those related to the line shape model and to the frequency scale. A deep comparison among the different molecules that have been selected in successful DBT implementations is also reported. Finally, for the first time, to the best of my knowledge, the influence of refractive index effects is discussed. PMID:26903093

  16. TIDDBIT HF Doppler Sounder Measurements of TIDs During the Wallops Island Rocket Launch of October 2007

    Science.gov (United States)

    Reynolds, A.; Crowley, G.; Rodrigues, F.; Earle, G.; Bullett, T.; Bishop, R.

    2008-12-01

    The TID Detector Built In Texas (TIDDBIT) sounder was deployed on the East Coast near Wallops Island to support a rocket launch in October 2007. The purpose of the rocket experiment was to study mid-latitude spread-F (MSF), and TIDDBIT provided information on the TID characteristics during the launch and for several days surrounding the launch. The sounder data confirm that waves were present during the rocket launch. This presentation reviews the TIDDBIT results from the experiment, contrasting data collected on different days, and from the same dates a year earlier. HF Doppler sounders represent a low-cost and low- maintenance solution for monitoring acoustic and gravity wave activity in the F-region ionosphere. HF Doppler sounders together with modern data analysis techniques provide both horizontal and vertical phase trace velocities across the entire TID spectrum from periods of 30-s to several hours. ASTRA has extensive experience with HF systems, and is currently building TIDDBIT sounders in New Mexico, and Peru.

  17. Linking the thermodynamic temperature to an optical frequency: recent advances in Doppler broadening thermometry.

    Science.gov (United States)

    Gianfrani, Livio

    2016-03-28

    Laser spectroscopy in the linear regime of radiation-matter interaction is a powerful tool for measuring thermodynamic quantities in a gas at thermodynamic equilibrium. In particular, the Doppler effect can be considered a gift of nature, linking the thermal energy to an optical frequency, namely the line centre frequency of an atomic or molecular spectral line. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry (DBT). This paper reports on the efforts that have been carried out, in the last decade, worldwide, to the end of making DBT competitive with more consolidated and accurate methodologies, such as acoustic gas thermometry and dielectric constant gas thermometry. The main requirements for low-uncertainty DBT, of both theoretical and technical nature, will be discussed, with a special focus on those related to the line shape model and to the frequency scale. A deep comparison among the different molecules that have been selected in successful DBT implementations is also reported. Finally, for the first time, to the best of my knowledge, the influence of refractive index effects is discussed. PMID:26903093

  18. Acoustics Discipline Overview

    Science.gov (United States)

    Envia, Edmane; Thomas, Russell

    2007-01-01

    As part of the Fundamental Aeronautics Program Annual Review, a summary of the progress made in 2007 in acoustics research under the Subsonic Fixed Wing project is given. The presentation describes highlights from in-house and external activities including partnerships and NRA-funded research with industry and academia. Brief progress reports from all acoustics Phase 1 NRAs are also included as are outlines of the planned activities for 2008 and all Phase 2 NRAs. N+1 and N+2 technology paths outlined for Subsonic Fixed Wing noise targets. NRA Round 1 progressing with focus on prediction method advancement. NRA Round 2 initiating work focused on N+2 technology, prediction methods, and validation. Excellent partnerships in progress supporting N+1 technology targets and providing key data sets.

  19. Acoustic Tractor Beam

    Science.gov (United States)

    Démoré, Christine E. M.; Dahl, Patrick M.; Yang, Zhengyi; Glynne-Jones, Peter; Melzer, Andreas; Cochran, Sandy; MacDonald, Michael P.; Spalding, Gabriel C.

    2014-05-01

    Negative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (>1 cm) to demonstrate the negative radiation forces and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to nonconservative forces, produced by redirection of a momentum flux from the angled sides of a target and not by conservative forces from a potential energy gradient. Use of a simple acoustic setup provides an easily understood illustration of the negative radiation pressure concept for tractor beams and demonstrates continuous attraction towards the source, against a net momentum flux in the system.

  20. Acoustic absorption by sunspots

    Science.gov (United States)

    Braun, D. C.; Labonte, B. J.; Duvall, T. L., Jr.

    1987-01-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity.

  1. Acoustic absorption by sunspots

    Energy Technology Data Exchange (ETDEWEB)

    Braun, D.C.; Labonte, B.J.; Duvall, T.L. Jr.

    1987-08-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity. 10 references.

  2. Sound decay of notes from acoustic guitars

    Science.gov (United States)

    Galazen, Erika; Nordberg, Joni; Huber, Thomas M.

    2005-09-01

    The acoustic guitar produces tones by transferring energy from the strings, through the bridge to the top plate, back, and air cavity of the guitar. The vibrations are ultimately radiated into the air as sound. The air-cavity and body resonances of the guitar play an important role in both the tone and the sustain (the time it takes notes to decay) produced by the guitar. To study the relationship between resonances of the guitar and the sustain of notes, the resonance frequencies were measured using a mechanical shaker attached to the body of the guitar and laser Doppler vibrometer to measure its vibration. A string was tuned to different frequencies and plucked. The decay of the note was measured with an electromagnetic pickup that measured the vibration of the string, a vibrometer to measure vibration of the top plate, and microphones located inside and outside the guitar. As expected, when the fundamental frequency of the string was near one of the resonances of the guitar, the decay rate was faster (shorter sustain) than when the string was between resonances. The relationship between the decay rates of the different parts of the system will also be discussed.

  3. Acoustic emission source modeling

    Directory of Open Access Journals (Sweden)

    Hora P.

    2010-07-01

    Full Text Available The paper deals with the acoustic emission (AE source modeling by means of FEM system COMSOL Multiphysics. The following types of sources are used: the spatially concentrated force and the double forces (dipole. The pulse excitation is studied in both cases. As a material is used steel. The computed displacements are compared with the exact analytical solution of point sources under consideration.

  4. The acoustics of snoring.

    Science.gov (United States)

    Pevernagie, Dirk; Aarts, Ronald M; De Meyer, Micheline

    2010-04-01

    Snoring is a prevalent disorder affecting 20-40% of the general population. The mechanism of snoring is vibration of anatomical structures in the pharyngeal airway. Flutter of the soft palate accounts for the harsh aspect of the snoring sound. Natural or drug-induced sleep is required for its appearance. Snoring is subject to many influences such as body position, sleep stage, route of breathing and the presence or absence of sleep-disordered breathing. Its presentation may be variable within or between nights. While snoring is generally perceived as a social nuisance, rating of its noisiness is subjective and, therefore, inconsistent. Objective assessment of snoring is important to evaluate the effect of treatment interventions. Moreover, snoring carries information relating to the site and degree of obstruction of the upper airway. If evidence for monolevel snoring at the site of the soft palate is provided, the patient may benefit from palatal surgery. These considerations have inspired researchers to scrutinize the acoustic characteristics of snoring events. Similarly to speech, snoring is produced in the vocal tract. Because of this analogy, existing techniques for speech analysis have been applied to evaluate snoring sounds. It appears that the pitch of the snoring sound is in the low-frequency range (noise-like', and has scattered energy content in the higher spectral sub-bands (>500 Hz). To evaluate acoustic properties of snoring, sleep nasendoscopy is often performed. Recent evidence suggests that the acoustic quality of snoring is markedly different in drug-induced sleep as compared with natural sleep. Most often, palatal surgery alters sound characteristics of snoring, but is no cure for this disorder. It is uncertain whether the perceived improvement after palatal surgery, as judged by the bed partner, is due to an altered sound spectrum. Whether some acoustic aspects of snoring, such as changes in pitch, have predictive value for the presence of

  5. Current-induced spin wave Doppler shift

    Science.gov (United States)

    Bailleul, Matthieu

    2010-03-01

    In metal ferromagnets -namely Fe, Co and Ni and their alloys- magnetism and electrical transport are strongly entangled (itinerant magnetism). This results in a number of properties such as the tunnel and giant magnetoresistance (i.e. the dependence of the electrical resistance on the magnetic state) and the more recently addressed spin transfer (i.e. the ability to manipulate the magnetic state with the help of an electrical current). The spin waves, being the low-energy elementary excitations of any ferromagnet, also exist in itinerant magnets, but they are expected to exhibit some peculiar properties due the itinerant character of the carriers. Accessing these specific properties experimentally could shed a new light on the microscopic mechanism governing itinerant magnetism, which -in turn- could help in optimizing material properties for spintronics applications. As a simple example of these specific properties, it was predicted theoretically that forcing a DC current through a ferromagnetic metal should induce a shift of the frequency of the spin waves [1,2]. This shift can be identified to a Doppler shift undergone by the electron system when it is put in motion by the electrical current. We will show how detailed spin wave measurements allow one to access this current-induced Doppler shift [3]. From an experimental point of view, we will discuss the peculiarities of propagating spin wave spectroscopy experiments carried out at a sub-micrometer length-scale and with MHz frequency resolution. Then, we will discuss the measured value of the Doppler shift in the context of both the old two-current model of spin-polarized transport and the more recent model of adiabatic spin transfer torque. [4pt] [1] P.Lederer and D.L. Mills, Phys.Rev. 148, 542 (1966).[0pt] [2] J. Fernandez-Rossier et al., Phys. Rev. B 69, 174412 (2004)[0pt] [3] V. Vlaminck and M. Bailleul, Science 322, 410 (2008).

  6. Sediment transfer from bar to beach? Measurements using a Pulse-Coherent Acoustic Doppler Profiler

    DEFF Research Database (Denmark)

    Aagaard, Troels; Hughes, Michael; Greenwood, Brian

    2011-01-01

    that is capable of recording suspended sediment transport at high resolution down to about 0.8 cm above the seabed. It was found that under accretionary fairweather conditions, a bar eroded and a beach berm accreted but the net suspended sediment transport across the trough was very small and seaward directed...

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

    DEFF Research Database (Denmark)

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

    In the majority of Danish streams, weed growth affects the effective stream width and bed roughness thus imposes temporal variations on the stage-discharge relationship. Small stream-gradients and firm ecology based restrictions prevent that hydraulic structures are made at the discharge stations...... and thus remove or limit such influences. Hence, estimation of the hydrograph is based on continuous stream gauging combined with monthly control measurements of discharge and assuming linear variation of bed roughness between the monthly measurements. As a result, any non-linear drift in weed density...... been placed at the main discharge station in one of the largest Danish catchments (the Skjern). The instruments were set out in early February 2010 during the winter season and have been running since then. The long term average discharge at the station is near 14 m3/s and the cross sectional profile...

  8. Acoustically enhanced heat transport

    Energy Technology Data Exchange (ETDEWEB)

    Ang, Kar M.; Hung, Yew Mun; Tan, Ming K., E-mail: tan.ming.kwang@monash.edu [School of Engineering, Monash University Malaysia, 47500 Bandar Sunway, Selangor (Malaysia); Yeo, Leslie Y. [Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3001 (Australia); Friend, James R. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093 (United States)

    2016-01-15

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10{sup 6} Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξ{sub s} ∼ 10{sup −9} m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξ{sub s} ∼ 10{sup −8} m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10{sup −8} m with 10{sup 6} Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.

  9. Acoustics, computers and measurements

    Science.gov (United States)

    Truchard, James J.

    2003-10-01

    The human ear has created a high standard for the requirements of acoustical measurements. The transient nature of most acoustical signals has limited the success of traditional volt meters. Professor Hixson's pioneering work in electroacoustical measurements at ARL and The University of Texas helped set the stage for modern computer-based measurements. The tremendous performance of modern PCs and extensive libraries of signal processing functions in virtual instrumentation application software has revolutionized the way acoustical measurements are made. Today's analog to digital converters have up to 24 bits of resolution with a dynamic range of over 120 dB and a single PC processor can process 112 channels of FFTs at 4 kHz in real time. Wavelet technology further extends the capabilities for analyzing transients. The tools available for measurements in speech, electroacoustics, noise, and vibration represent some of the most advanced measurement tools available. During the last 50 years, Professor Hixson has helped drive this revolution from simple oscilloscope measurements to the modern high performance computer-based measurements.

  10. Neutral wind results from TIMED Doppler interferometer

    Science.gov (United States)

    Killeen, T.; Gablehouse, R.; Gell, D.; Johnson, R.; Niciejewski, R.; Ortland, D.; Wu, Q.; Skinner, W.; Solomon, S.; Kafkalidis, J.

    2003-04-01

    Since the launch of the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite in December 2001, the TIMED Doppler Interferometer (TIDI) has been collecting lower thermosphere and mesospheric data for over a year. After adjustments to the spectral sampling scheme and operational mode, the instrument has been optimized. Efforts have also been made to improve the instrument performance. Preliminary neutral winds from O2 (0-0) have been analyzed. Tidal features and their seasonal variation are shown clearly in the wind data, which are quantitatively consistent with model prediction. We will report our progress on these efforts.

  11. Transmission media effects on precise Doppler tracking

    Science.gov (United States)

    Callahan, P. S.

    1978-01-01

    The effects of the transmission media - the earth's troposphere and ionosphere, and the solar wind - on precise Doppler tracking are discussed. The charged particle effects can be largely removed by dual frequency observations; however there are limitations to these corrections (besides system noise and/or finite integration times) including the effects of magnetic fields, diffraction, and differential refraction, all of which must be carefully evaluated. The earth's troposphere can contribute an error of delta f/f approximately 10 to the minus 14th power.

  12. [Color Doppler sonography of focal abdominal lesions].

    Science.gov (United States)

    Licanin, Zoran; Lincender, Lidija; Djurović, V; Salihefendić, Nizama; Smajlović, Fahrudin

    2004-01-01

    Color Doppler sonography (CDS--spectral, color and power), harmonic imaging techniques (THI, PHI), possibility of 3D analysis of picture, usage of contrast agents, have raised the values of ultrasound as a diagnostic method to a very high level. THI--non-linear gray scale modality, is based on the processing of higher reflected frequencies, that has improved a picture resolution, which is presented with less artifacts and limiting effects of obesity and gases. Ultrasound contrast agents improve analysis of micro and macro circulation of the examined area, and with the assessment of velocity of supply in ROI (wash in), distribution and time of signal weakening (wash out), are significantly increasing diagnostic value of ultrasound. Besides the anatomical and topographic presentation of examined region (color, power), Color Doppler sonography gives us haemodynamic-functional information on vascularisation of that region, as well as on pathologic vascularisation if present. Avascular aspect of a focal pathologic lesion corresponds to a cyst or haematoma, while coloration and positive spectral curve discover that anechogenic lesions actually represents aneurysms, pseudoaneurysms or AVF. In local inflammatory lesion, abscess in an acute phase, CDS shows first increased, and then decreased central perfusion, while in a chronic phase, a pericapsular vascularisation is present. Contribution of CDS in differentiation of hepatic tumors (hemangioma, HCC and metastasis) is very significant. Central color dots along the peripheral blood vessels and the blush phenomenon are characteristics of capillary hemangioma, peritumoral vascular ring "basket" of HCC, and "detour" sign of metastasis. The central artery, RI from 0.45 to 0.60 and radial spreading characterize FNH. Hepatic adenoma is characterized by an intratumoral vein, and rarely by a vascular hallo. Further on, blood velocity in tumor defined by Color Doppler, distinguishes malignant from benign lesion, where 40 cm/s is a

  13. Doppler cooling to the quantum limit.

    Science.gov (United States)

    Chalony, M; Kastberg, A; Klappauf, B; Wilkowski, D

    2011-12-01

    Doppler cooling on a narrow transition is limited by the noise of single scattering events. It shows novel features, which are in sharp contrast with cooling on a broad transition, such as a non-gaussian momentum distribution, and divergence of its mean square value close to the resonance. We have observed those features using 1D cooling on an intercombination transition in strontium, and compared the measurements with theoretical predictions and Monte Carlo simulations. We also find that for very a narrow transition, cooling can be improved using a dipole trap, where the clock shift is canceled. PMID:22242994

  14. Doppler cooling and trapping on forbidden transitions

    OpenAIRE

    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...

  15. Doppler cooling to the Quantum limit

    CERN Document Server

    Chalony, Maryvonne; Klappauf, Bruce; Wilkowski, David

    2011-01-01

    Doppler cooling on a narrow transition is limited by the noise of single scattering events. It shows novel features, which are in sharp contrast with cooling on a broad transition, such as a non-Gaussian momentum distribution, and divergence of its mean square value close to the resonance. We have observed those features using 1D cooling on an intercombination transition in strontium, and compared the measurements with theoretical predictions and Monte Carlo simulations. We also find that for very a narrow transition, cooling can be improved using a dipole trap, where the clock shift is canceled.

  16. Moessbauer spectroscopy - applications of the Doppler principle

    International Nuclear Information System (INIS)

    Moessbauer spectroscopy is an experimental method based on the application of the Doppler principle in the velocity modulation system for variation of γ-ray energy. The object of observations is a resonating nucleus. From Moessbauer spectra one can gain information on the electronic and magnetic environment (based on hyperfine interactions) and on the vibrational states of atoms (based on the Debey-Waller factor). It is a typical microscopic method which has found applications in all disciplines of natural sciences as well as in medicine, art, archaeology and materials science. (author) 5 figs., 37 refs

  17. Fundamentals of Shallow Water Acoustics

    CERN Document Server

    Katsnelson, Boris; Lynch, James

    2012-01-01

    Shallow water acoustics (SWA), the study of how low and medium frequency sound propagates and scatters on the continental shelves of the world's oceans, has both technical interest and a large number of practical applications. Technically, shallow water poses an interesting medium for the study of acoustic scattering, inverse theory, and propagation physics in a complicated oceanic waveguide. Practically, shallow water acoustics has interest for geophysical exploration, marine mammal studies, and naval applications. Additionally, one notes the very interdisciplinary nature of shallow water acoustics, including acoustical physics, physical oceanography, marine geology, and marine biology. In this specialized volume, the authors, all of whom have extensive at-sea experience in U.S. and Russian research efforts, have tried to summarize the main experimental, theoretical, and computational results in shallow water acoustics, with an emphasis on providing physical insight into the topics presented.

  18. Latest Trends in Acoustic Sensing

    Directory of Open Access Journals (Sweden)

    Cinzia Caliendo

    2014-03-01

    Full Text Available Acoustics-based methods offer a powerful tool for sensing applications. Acoustic sensors can be applied in many fields ranging from materials characterization, structural health monitoring, acoustic imaging, defect characterization, etc., to name just a few. A proper selection of the acoustic wave frequency over a wide spectrum that extends from infrasound (<20 Hz up to ultrasound (in the GHz–band, together with a number of different propagating modes, including bulk longitudinal and shear waves, surface waves, plate modes, etc., allow acoustic tools to be successfully applied to the characterization of gaseous, solid and liquid environments. The purpose of this special issue is to provide an overview of the research trends in acoustic wave sensing through some cases that are representative of specific applications in different sensing fields.

  19. High-Frequency Seafloor Acoustics

    CERN Document Server

    Jackson, Darrell R

    2007-01-01

    High-Frequency Seafloor Acoustics is the first book in a new series sponsored by the Office of Naval Research on the latest research in underwater acoustics. This exciting new title provides ready access to experimental data, theory, and models relevant to high-frequency seafloor acoustics and will be of interest to sonar engineers and researchers working in underwater acoustics. The physical characteristics of the seafloor affecting acoustic propagation and scattering are covered, including physical and geoacoustic properties and surface roughness. Current theories for acoustic propagation in sediments are presented along with corresponding models for reflection, scattering, and seafloor penetration. The main text is backed up by an extensive bibliography and technical appendices.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-07-01

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

  1. Acoustical coupling of lizard eardrums

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, Jakob; Manley, Geoffrey A

    2008-01-01

    Lizard ears are clear examples of two-input pressure-difference receivers, with up to 40-dB differences in eardrum vibration amplitude in response to ipsi- and contralateral stimulus directions. The directionality is created by acoustical coupling of the eardrums and interaction of the direct...... is caused by the acoustic interaction of the two eardrums. The results can be largely explained by a simple acoustical model based on an electrical analog circuit....

  2. Room acoustic auralization with Ambisonics

    OpenAIRE

    Polack, Jean-Dominique; Leão Figueiredo, Fábio

    2012-01-01

    International audience During the year of 2009, the room acoustics group of the LAM (Équipe Lutheries, Acoustique, Musique de l’Institut Jean Le Rond d’Alembert - Université Pierre et Marie Curie, Paris) performed a series of acoustical measurements in music halls in Paris. The halls were chosen in regarding their importance to the historic, architectural or acoustic domains. The measured ensemble of fourteen rooms includes quite different architectural designs. The measurements were carri...

  3. Combined Environment Acoustic Chamber (CEAC)

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose: The CEAC imposes combined acoustic, thermal and mechanical loads on aerospace structures. The CEAC is employed to measure structural response and determine...

  4. Compressive sensing for high resolution profiles with enhanced Doppler performance

    NARCIS (Netherlands)

    Anitori, L.; Hoogeboom, P.; Chevalier, F. Le; Otten, M.P.G.

    2012-01-01

    In this paper we demonstrate how Compressive Sensing (CS) can be used in pulse-Doppler radars to improve the Doppler performance while preserving range resolution. We investigate here two types of stepped frequency waveforms, the coherent frequency bursts and successive frequency ramps, which can be

  5. "An analysis of the classical Doppler Effect"[1] revisited

    OpenAIRE

    Rothenstein, Bernhard; Nafornita, Corina

    2004-01-01

    After having shown that the formula which describes the Doppler effect in the general case holds only in the case of the "very high" frequency assumption, we derive free of assumptions Doppler formulas for two scenarios presented in the revisited paper.

  6. Measurement of depth of burns by laser Doppler perfusion imaging

    NARCIS (Netherlands)

    Droog, E.J.; Steenbergen, W.; Sjöberg, F.

    2001-01-01

    Laser Doppler perfusion imaging (LDPI), is a further development in laser Doppler flowmetry (LDF). Its advantage is that it enables assessment of microvascular blood flow in a predefined skin area rather than, as for LDF, in one place. In many ways this method seems to be more promising than LDF in

  7. Micro-Doppler classification of riders and riderless horses

    Science.gov (United States)

    Tahmoush, David

    2014-05-01

    Micro-range Micro-Doppler can be used to isolate particular parts of the radar signature, and in this case we demonstrate the differences in the signature between a walking horse versus a walking horse with a rider. Using micro-range micro-Doppler, we can distinguish the radar returns from the rider as separate from the radar returns of the horse.

  8. A study for developing an ultrasonic Doppler flowmeter

    Science.gov (United States)

    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%.

  9. Doppler weather radar with predictive wind shear detection capabilities

    Science.gov (United States)

    Kuntman, Daryal

    1991-01-01

    The status of Bendix research on Doppler weather radar with predictive wind shear detection capability is given in viewgraph form. Information is given on the RDR-4A, a fully coherent, solid state transmitter having Doppler turbulence capability. Frequency generation data, plans, modifications, system characteristics and certification requirements are covered.

  10. Functional Doppler optical coherence tomography for cortical blood flow imaging

    Science.gov (United States)

    Yu, Lingfeng; Liu, Gangjun; Nguyen, Elaine; Choi, Bernard; Chen, Zhongping

    2010-02-01

    Optical methods have been widely used in basic neuroscience research to study the cerebral blood flow dynamics in order to overcome the low spatial resolution associated with magnetic resonance imaging and positron emission tomography. Although laser Doppler imaging and laser speckle imaging can map out en face cortical hemodynamics and columns, depth resolution is not available. Two-photon microscopy has been used for mapping cortical activity. However, flow measurement requires fluorescent dye injection, which can be problematic. The noninvasive and high resolution tomographic capabilities of optical coherence tomography make it a promising technique for mapping depth resolved cortical blood flow. Here, we present a functional Doppler optical coherence tomography (OCT) imaging modality for quantitative evaluation of cortical blood flow in a mouse model. Fast, repeated, Doppler OCT scans across a vessel of interest were performed to record flow dynamic information with a high temporal resolution of the cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time, thereby providing complementary temporal flow information to the spatially distributed flow information of Doppler OCT. The proposed functional Doppler OCT imaging modality can be used to diagnose vessel stenosis/blockage or monitor blood flow changes due to pharmacological agents/neuronal activities. Non-invasive in-vivo mice experiments were performed to verify the capabilities of function Doppler OCT.

  11. Musculoskeletal colour/power Doppler in sports medicine

    DEFF Research Database (Denmark)

    Boesen, M I; Boesen, M; Langberg, Henning;

    2010-01-01

    This review article discusses the aspects of sports medicine where musculoskeletal Doppler ultrasound has valuable contribution in diagnosis and/or treatment of some of the typical musculoskeletal sports injuries. Also, conditions where the Doppler ultrasound has no value are discussed. Some...

  12. Lumen pressure within obliquely insonated absorbent solid cylindrical shells with application to Doppler flow phantoms.

    Science.gov (United States)

    Steel, Robin; Fish, Peter J

    2002-02-01

    Flow phantoms used in medical ultrasound usually employ a plastic tube as a blood vessel mimic. These tubes often have acoustic properties differing significantly from the tissue and blood-mimicking media, which results in distortion of the acoustic pressure field within the tubes and, hence, of the Doppler flow spectra. Previous analyses of this problem have used some form of the infinite plate transmission coefficient, although at least one ray-based analysis has considered a cylindrical interface but with zero wall thickness. In this paper, we compare these approximate pressure fields with the exact solution for oblique incidence on a viscoelastic cylindrical shell at 5 MHz to find for which materials the plate approximation is valid. The shell has water both inside and outside, but it can be modified to use a different fluid inside and also to include absorption in either fluid. We find the plate approximation is reasonable for soft tubes such as the copolymer Cflex (Cole-Palmer, Niles, IL) but much less so for hard tubes such as polymethylmethacrylate (PMMA). PMID:11885684

  13. Acoustic transparency and slow sound using detuned acoustic resonators

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco; Bozhevolnyi, Sergey I.

    2011-01-01

    We demonstrate that the phenomenon of acoustic transparency and slowsound propagation can be realized with detuned acoustic resonators (DAR), mimicking thereby the effect of electromagnetically induced transparency (EIT) in atomic physics. Sound propagation in a pipe with a series of side...

  14. Embolic Doppler ultrasound signal detection via fractional Fourier transform.

    Science.gov (United States)

    Gençer, Merve; Bilgin, Gökhan; Aydın, Nizamettin

    2013-01-01

    Computerized analysis of Doppler ultrasound signals can aid early detection of asymptomatic circulating emboli. For analysis, physicians use informative features extracted from Doppler ultrasound signals. Time -frequency analysis methods are useful tools to exploit the transient like signals such as Embolic signals. Detection of discriminative features would be the first step toward automated analysis of embolic Doppler ultrasound signals. The most problematic part of setting up emboli detection system is to differentiate embolic signals from confusing similar wave-like patterns such as Doppler speckle and artifacts caused by tissue movement, probe tapping, speaking etc. In this study, discrete version of fractional Fourier transform is presented as a solution in the detection of emboli in digitized Doppler ultrasound signals. An accurate set of parameters are extracted using short time Fourier transform and fractional Fourier transform and the results are compared to reveal detection quality. Experimental results prove the efficiency of fractional Fourier transform in which discriminative features becomes more evident.

  15. Use of GPS network data for HF Doppler measurements interpretation

    CERN Document Server

    Petrova, Inna R; Latypov, Ruslan R

    2014-01-01

    The method of measurement of Doppler frequency shift of ionospheric signal - HF Doppler technique - is one of well-known and widely used methods of ionosphere research. It allows to research various disturbances in the ionosphere. There are some sources of disturbances in the ionosphere. These are geomagnetic storms, solar flashes, metrological effects, atmospheric waves. This method allows to find out the influence of earthquakes, explosions and other processes on the ionosphere, which occur near to the Earth. HF Doppler technique has the high sensitivity to small frequency variations and the high time resolution, but interpretation of results is difficult. In this work we make an attempt to use GPS data for Doppler measurements interpretation. Modeling of Doppler frequency shift variations with use of TEC allows to separate ionosphere disturbances of medium scale.

  16. Doplerovi brodski navigacioni brzinomjeri / Maritime navigational Doppler logs

    Directory of Open Access Journals (Sweden)

    Milovan Unković

    2006-01-01

    Full Text Available Doplerovi navigacioni brodski brzinomjeri rade na principu Doplerovog efekta. Doplerov predajni projektor emituje snop ultrazvučnih vibracija u vodi, a drugi (ili isti projektor prima odbijeni signal od dna ili od sloja vode. U ovom radu opisana je teorija Doplerovog efekta, primjena te teorije na brodskim brzinomjerima, konstrukcija i karakteristike savremenih Doplerovih brzinomjera. / The Doppler maritime navigational logs are based on measurement of the Doppler effect. A Doppler log transmitting transducer emits beam of sound vibration in the water, and a second (or the same transducer receives the echo from the sea bed or -water layer. In this article describes theory of Doppler effect, using this theory in maritime logs, construction and performance of modern Doppler logs.

  17. Ionospheric Doppler measurements by means of HF-radar techniques

    Directory of Open Access Journals (Sweden)

    D. Altadill

    2005-06-01

    Full Text Available Studies of the dynamics of the ionosphere and its related phenomena are mainly based on Doppler Drift measurements. The time variation (ionisation/recombination of plasma density, thermospheric wind and others can be observed by means of HF-radars. The technique of Doppler Drift measurements is a quite complex technique that is now affordable by means of an advanced ionospheric sounder. The combination of vertical sounding and interferometric Doppler detection discloses the Doppler sources. The echo signal contains the Doppler shift in frequency imposed on the wave carrier by each point source where the signal is reflected. Other phenomena like environmental noise and the intrinsic error of the measurements that, together with the change in time of the refractive index, affect the measurements in various ways impeding to better quantify the results.

  18. Doppler-cancelled response to VLF gravitational waves

    Science.gov (United States)

    Caporali, A.

    1981-01-01

    The interaction of long periodic gravitational waves with a three link microwave system known as the Doppler Cancelling System is discussed. This system, which was developed for a gravitational redshift experiment, uses one-way and two-way Doppler informatin to construct the beat signal of two reference oscillators moving with respect to each other. The geometric optics approximation is used to derive the frequency shift produced on a light signal propagating in a gravitational wave space-time. The signature left on the Doppler-cancelled beat by burst and continuous gravitational waves is analyzed. A comparison is made between the response to gravitational waves of the Doppler Cancelling System and that of a Doppler tracking system which employs two-way, round-trip radio waves. A three-fold repetition of the gravitational wave form is found to be a common feature of the response functions of both systems. These two functions otherwise exhibit interesting differences.

  19. Limits on Planetary Companions from Doppler Surveys of Nearby Stars

    CERN Document Server

    Howard, Andrew W

    2016-01-01

    Most of our knowledge of planets orbiting nearby stars comes from Doppler surveys. For spaced-based, high-contrast imaging missions, nearby stars with Doppler-discovered planets are attractive targets. The known orbits tell imaging missions where and when to observe, and the dynamically-determined masses provide important constraints for the interpretation of planetary spectra. Quantifying the set of planet masses and orbits that could have been detected will enable more efficient planet discovery and characterization. We analyzed Doppler measurements from Lick and Keck Observatories collected by the California Planet Survey. We focused on stars that are likely targets for three space-based planet imaging mission concepts studied by NASA--WFIRST-AFTA, Exo-C, and Exo-S. The Doppler targets are primarily F8 and later main sequence stars, with observations spanning 1987-2014. We identified 76 stars with Doppler measurements from the prospective mission target lists. We developed an automated planet search and a ...

  20. Acoustic Mechanical Feedthroughs

    Science.gov (United States)

    Sherrit, Stewart; Walkemeyer, Phillip; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea

    2013-01-01

    Electromagnetic motors can have problems when operating in extreme environments. In addition, if one needs to do mechanical work outside a structure, electrical feedthroughs are required to transport the electric power to drive the motor. In this paper, we present designs for driving rotary and linear motors by pumping stress waves across a structure or barrier. We accomplish this by designing a piezoelectric actuator on one side of the structure and a resonance structure that is matched to the piezoelectric resonance of the actuator on the other side. Typically, piezoelectric motors can be designed with high torques and lower speeds without the need for gears. One can also use other actuation materials such as electrostrictive, or magnetostrictive materials in a benign environment and transmit the power in acoustic form as a stress wave and actuate mechanisms that are external to the benign environment. This technology removes the need to perforate a structure and allows work to be done directly on the other side of a structure without the use of electrical feedthroughs, which can weaken the structure, pipe, or vessel. Acoustic energy is pumped as a stress wave at a set frequency or range of frequencies to produce rotary or linear motion in a structure. This method of transferring useful mechanical work across solid barriers by pumping acoustic energy through a resonant structure features the ability to transfer work (rotary or linear motion) across pressure or thermal barriers, or in a sterile environment, without generating contaminants. Reflectors in the wall of barriers can be designed to enhance the efficiency of the energy/power transmission. The method features the ability to produce a bi-directional driving mechanism using higher-mode resonances. There are a variety of applications where the presence of a motor is complicated by thermal or chemical environments that would be hostile to the motor components and reduce life and, in some instances, not be

  1. Taming Acoustic Cavitation

    CERN Document Server

    Rivas, David Fernandez; Enriquez, Oscar R; Versluis, Michel; Prosperetti, Andrea; Gardeniers, Han; Lohse, Detlef

    2012-01-01

    In this fluid dynamics video we show acoustic cavitation occurring from pits etched on a silicon surface. By immersing the surface in a liquid, gas pockets are entrapped in the pits which upon ultrasonic insonation, are observed to shed cavitation bubbles. Modulating the driving pressure it is possible to induce different behaviours based on the force balance that determines the interaction among bubbles and the silicon surface. This system can be used for several applications like sonochemical water treatment, cleaning of surfaces with deposited materials such as biofilms.

  2. Lecture Notes On Acoustics

    International Nuclear Information System (INIS)

    This book mentions string vibration and wave, one-dimension wave and wave equation, characteristic impedance, governing equation of string, and wave energy from string, wave equation of wave and basic physical quantity like one-dimension wave equation, sound unit, sound intensity and energy, sound movement in a surface of discontinuity with transmission loss of sound by partition, and Snell's law, radiation, scatter and diffraction and sound in closed space with Sabine's theory, sound characteristic of closed space and duct acoustics.

  3. Dynamic acoustic tractor beams

    Energy Technology Data Exchange (ETDEWEB)

    Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology – ETC, Santa Fe, New Mexico 87508 (United States)

    2015-03-07

    Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.

  4. Dynamic acoustic tractor beams

    Science.gov (United States)

    Mitri, F. G.

    2015-03-01

    Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.

  5. Fast acoustic streaming in standing waves: generation of an additional outer streaming cell.

    Science.gov (United States)

    Reyt, Ida; Daru, Virginie; Bailliet, Hélène; Moreau, Solène; Valière, Jean-Christophe; Baltean-Carlès, Diana; Weisman, Catherine

    2013-09-01

    Rayleigh streaming in a cylindrical acoustic standing waveguide is studied both experimentally and numerically for nonlinear Reynolds numbers from 1 to 30 [Re(NL)=(U0/c0)(2)(R/δν)(2), with U0 the acoustic velocity amplitude at the velocity antinode, c0 the speed of sound, R the tube radius, and δν the acoustic boundary layer thickness]. Streaming velocity is measured by means of laser Doppler velocimetry in a cylindrical resonator filled with air at atmospheric pressure at high intensity sound levels. The compressible Navier-Stokes equations are solved numerically with high resolution finite difference schemes. The resonator is excited by shaking it along the axis at imposed frequency. Results of measurements and of numerical calculation are compared with results given in the literature and with each other. As expected, the axial streaming velocity measured and calculated agrees reasonably well with the slow streaming theory for small ReNL but deviates significantly from such predictions for fast streaming (ReNL>1). Both experimental and numerical results show that when ReNL is increased, the center of the outer streaming cells are pushed toward the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes.

  6. Development of a Multi-Channel Piezoelectric Acoustic Sensor Based on an Artificial Basilar Membrane

    Directory of Open Access Journals (Sweden)

    Youngdo Jung

    2013-12-01

    Full Text Available In this research, we have developed a multi-channel piezoelectric acoustic sensor (McPAS that mimics the function of the natural basilar membrane capable of separating incoming acoustic signals mechanically by their frequency and generating corresponding electrical signals. The McPAS operates without an external energy source and signal processing unit with a vibrating piezoelectric thin film membrane. The shape of the vibrating membrane was chosen to be trapezoidal such that different locations of membrane have different local resonance frequencies. The length of the membrane is 28 mm and the width of the membrane varies from 1 mm to 8 mm. Multiphysics finite element analysis (FEA was carried out to predict and design the mechanical behaviors and piezoelectric response of the McPAS model. The designed McPAS was fabricated with a MEMS fabrication process based on the simulated results. The fabricated device was tested with a mouth simulator to measure its mechanical and piezoelectrical frequency response with a laser Doppler vibrometer and acoustic signal analyzer. The experimental results show that the as fabricated McPAS can successfully separate incoming acoustic signals within the 2.5 kHz–13.5 kHz range and the maximum electrical signal output upon acoustic signal input of 94 dBSPL was 6.33 mVpp. The performance of the fabricated McPAS coincided well with the designed parameters.

  7. Theory and signal processing of acoustic correlation techniques for current velocity measurement

    Institute of Scientific and Technical Information of China (English)

    ZHU Weiqing; FENG Lei; WANG Changhong; WANG Yuling; QIU Wei

    2008-01-01

    A theoretical model and signal processing of acoustic correlation measurements to estimate current velocity are discussed. The sonar space-time correlation function of vol-ume reverberations within Fraunhofer zone is derived. The function, which is in exponential forms, is the theoretical model of acoustic correlation measurements. The characteristics of the correlation values around the maximum of the amplitude of the correlation function, where most information about current velocity is contained, are primarily analyzed. Localized Least Mean Squares (LLMS) criterion is put forward for velocity estimation. Sequential Quadratic Programming (SQP) method is adopted as the optimization method. So the systematic sig-nal processing method of acoustic correlation techniques for current velocity measurement is established. A prototype acoustic correlation current profiler (ACCP) underwent several sea trials, the results show that theoretical model approximately coincides with experimental re-sults. Current profiles including the speed and direction from ACCP are compared with those from acoustic Doppler current profiler (ADCP). The current profiles by both instruments agree reasonably well. Also, the standard deviation of velocity measurement by ACCP is statistically calculated and it is a little larger than predicted value.

  8. TIMED Doppler Interferometer: Overview and recent results

    Science.gov (United States)

    Killeen, T. L.; Wu, Q.; Solomon, S. C.; Ortland, D. A.; Skinner, W. R.; Niciejewski, R. J.; Gell, D. A.

    2006-10-01

    The Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite carries a limb-scanning Fabry-Perot interferometer designed to perform remote-sensing measurements of upper atmosphere winds and temperatures globally. This instrument is called the TIMED Doppler Interferometer, or TIDI. This paper provides an overview of the TIDI instrument design, on-orbit performance, operational modes, data processing and inversion procedures, and a summary of wind results to date. Daytime and nighttime neutral winds in the mesosphere and lower thermosphere/ionosphere (MLTI) are measured on TIDI using four individual scanning telescopes that collect light from various upper atmosphere airglow layers on both the cold and warm sides of the high-inclination TIMED spacecraft. The light is spectrally analyzed using an ultrastable plane etalon Fabry-Perot system with sufficient spectral resolution to determine the Doppler line characteristics of atomic and molecular emissions emanating from the MLTI. The light from all four telescopes and from an internal calibration field passes through the etalon and is combined on a single image plane detector using a Circle-to-Line Interferometer Optic (CLIO). The four geophysical fields provide orthogonal line-of-sight measurements to either side of the satellite's path and these are analyzed to produce altitude profiles of vector winds in the MLTI. The TIDI wind measurements presented here are from the molecular oxygen (0-0) band, covering the altitude region 85-105 km. The unique TIDI design allows for more extended local time coverage of wind structures than previous wind-measuring instruments from high-inclination satellites. The TIDI operational performance has been nominal except for two anomalies: (1) higher than expected background white light caused by a low-level light leak and (2) ice deposition on cold optical surfaces. Both anomalies are well understood and the instrumental modes and data analysis techniques have been

  9. Acoustic Similarity and Dichotic Listening.

    Science.gov (United States)

    Benson, Peter

    1978-01-01

    An experiment tests conjectures that right ear advantage (REA) has an auditory origin in competition or interference between acoustically similar stimuli and that feature-sharing effect (FSE) has its origin in assignment of features of phonetically similar stimuli. No effect on the REA for acoustic similarity, and a clear effect of acoustic…

  10. Acoustic Center or Time Origin?

    DEFF Research Database (Denmark)

    Staffeldt, Henrik

    1999-01-01

    The paper discusses the acoustic center in relation to measurements of loudspeaker polar data. Also, it presents the related concept time origin and discusses the deviation that appears between positions of the acoustic center found by wavefront based and time based measuring methods....

  11. Digital Controller For Acoustic Levitation

    Science.gov (United States)

    Tarver, D. Kent

    1989-01-01

    Acoustic driver digitally controls sound fields along three axes. Allows computerized acoustic levitation and manipulation of small objects for such purposes as containerless processing and nuclear-fusion power experiments. Also used for controlling motion of vibration-testing tables in three dimensions.

  12. Propagation of Ion Acoustic Perturbations

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1975-01-01

    Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered.......Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered....

  13. The endoscopic Doppler: its value in evaluating gastroduodenal ulcers after hemorrhage and as an instrument of control of endoscopic injection theraphy

    Energy Technology Data Exchange (ETDEWEB)

    Kohler, B.; Riemann, F. (Medical Clinic C, Ludwigshafen (Germany, F.R.))

    1991-01-01

    In this prospective study of 80 patients with active bleeding from the gastrointestinal tract, a Doppler ultrasonographic investigation of the gastroduodenal ulcers was performed, in addition to immediate endoscopic examination. Admitted to this study were ulcers with the stigmata of acute bleeding, such as a visible blood vessel in the ulcer floor, a blood clot or a black base, and Forrest III lesions. In 52 patients Doppler ultrasonography was able to document unequivocally a superficial blood vessel. Complete agreement of endoscopic and Doppler results was obtained in only 49% of the cases. When a blood vessel was positively identified, local injection of epinephrine and polidocanol was carried out. Tereupon, in the further course, the acoustic signal was shifted into deeper regions or disappeared entirely. In 8% of the cases initial sclerosing was followed by a rebleed, which was again treated by injection therapy. None of the patients died of their GI hemorrhage. Endoscopic Doppler ultrasonography is a new and effective procedure that enables objectification of the endoscopic findings. It identifies the indication for proceeding to operative endoscopy and can monitor the effectiveness of the latter. 27 refs., 1 fig., 3 tabs.

  14. Ultrasonic intrusion sensor using the Doppler effect; Choonpa Doppler hoshiki shinnyu sensor

    Energy Technology Data Exchange (ETDEWEB)

    Kani, H.; Iwasaki, N.; Goto, M. [Nippon Soken, Inc., Tokyo (Japan); Tsuzuki, T.; Nakamura, T. [Denso Corp., Aichi (Japan)

    1997-10-01

    For vehicle anti-theft alarm systems which cope with vehicle and car component theft, EU initiated vehicle security regulations from Jan 1997. Also, the insurance industry has instituted the insurance certification of vehicle anti-theft alarm systems. We have developed an ultrasonic intrusion sensor using the doppler effect for vehicle anti-theft alarm systems specifically for these EU regulations and insurance certification. 2 refs., 7 figs., 1 tab.

  15. MEMS Based Acoustic Array

    Science.gov (United States)

    Sheplak, Mark (Inventor); Nishida, Toshikaza (Inventor); Humphreys, William M. (Inventor); Arnold, David P. (Inventor)

    2006-01-01

    Embodiments of the present invention described and shown in the specification aid drawings include a combination responsive to an acoustic wave that can be utilized as a dynamic pressure sensor. In one embodiment of the present invention, the combination has a substrate having a first surface and an opposite second surface, a microphone positioned on the first surface of the substrate and having an input and a first output and a second output, wherein the input receives a biased voltage, and the microphone generates an output signal responsive to the acoustic wave between the first output and the second output. The combination further has an amplifier positioned on the first surface of the substrate and having a first input and a second input and an output, wherein the first input of the amplifier is electrically coupled to the first output of the microphone and the second input of the amplifier is electrically coupled to the second output of the microphone for receiving the output sinual from the microphone. The amplifier is spaced from the microphone with a separation smaller than 0.5 mm.

  16. Acoustics and Hearing

    CERN Document Server

    Damaske, Peter

    2008-01-01

    When one listens to music at home, one would like to have an acoustic impression close to that of being in the concert hall. Until recently this meant elaborate multi-channelled sound systems with 5 or more speakers. But head-related stereophony achieves the surround-sound effect in living rooms with only two loudspeakers. By virtue of their slight directivity as well as an electronic filter the limitations previously common to two-speaker systems can be overcome and this holds for any arbitrary two-channel recording. The book also investigates the question of how a wide and diffuse sound image can arise in concert halls and shows that the quality of concert halls decisively depends on diffuse sound images arising in the onset of reverberation. For this purpose a strong onset of reverberation is modified in an anechoic chamber by electroacoustic means. Acoustics and Hearing proposes ideas concerning signal processing in the auditory system that explain the measured results and the resultant sound effects plea...

  17. Acoustic data transmission method

    Energy Technology Data Exchange (ETDEWEB)

    Duckworth, A.

    1991-09-17

    This patent describes a method for transmitting time line data through a drillstring having drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints. It comprises generating acoustic data signals having a single frequency content in at least one passband of the drillstring; transmitting the data signals through the drillstring from either the first location to the second location or from the second location to the first location during a time period prior to the onset of reflective interference caused by the data signals reflecting from along the length of the drillstring, the time period being equal to or less than the time for the data signals to travel three lengths of the drillstring; stopping the transmission of data signals at the onset of the reflective interference and allowing the acoustic signals to substantially attenuate; and detecting the data signals at the respective first or second location.

  18. Fractal fluctuations in transcranial Doppler signals

    Science.gov (United States)

    West, B. J.; Zhang, R.; Sanders, A. W.; Miniyar, S.; Zuckerman, J. H.; Levine, B. D.

    1999-03-01

    Cerebral blood flow (CBF) velocity measured using transcranial Doppler ultrasonography (TCD) is not strictly constant, but has both a systematic and random component. This behavior may indicate that the axial blood flow in the middle cerebral artery is a chaotic process. Herein we use the relative dispersion, the ratio of the standard deviation to the mean, to show by systematically aggregating the data that the correlation in the beat-to-beat CBF time series is a modulated inverse power law. This scaling of the CBF time series indicates the existence of long-time memory in the underlying control process. We argue herein that the control system has allometric properties that enable it to maintain a relatively constant brain perfusion.

  19. Implementation of Doppler backscattering for MAST

    CERN Document Server

    Hillesheim, J C; Peebles, W A; Meyer, H; Meakins, A; Field, A R; Dunai, D; Carr, M; Hawkes, N

    2014-01-01

    A sixteen channel millimeter-wave diagnostic system, covering the frequency range 30-75 GHz, has been installed on MAST [B. Lloyd et al., Nucl. Fusion 43, 1665 (2003)] and has been successfully used for both Doppler backscattering (DBS) and conventional (normal-incidence) fluctuation reflectometry. DBS has become a well-established and versatile diagnostic technique for the measurement of intermediate- k ($k_{\\bot} \\rho_i \\sim 1$, and higher) density fluctuations and flows in magnetically confined fusion experiments. The $180^{\\circ}$ backscattering for DBS requires three dimensional wave-vector matching between the launched beam and the plasma fluctuations inducing the scattering, which are expected to be highly elongated along the magnetic field. The large pitch angle in MAST means that DBS implementation depends strongly on the capability to accurately launch the probing beam at a toroidal and poloidal angle that is matched to the magnetic field at the scattering location. We report on the scattering consi...

  20. Doppler cooling and trapping on forbidden transitions

    CERN Document Server

    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.

  1. Doppler cooling and trapping on forbidden transitions.

    Science.gov (United States)

    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

  2. The Doppler peaks from a generic defect

    CERN Document Server

    Magueijo, J

    1996-01-01

    We investigate which of the exotic Doppler peak features found for textures and cosmic strings are generic novelties pertaining to defects. We find that the ``out of phase'' texture signature is an accident. Generic defects, when they generate a secondary peak structure similar to inflation, apply to it an additive shift. It is not necessary for this shift to be ``out of phase''. We also show which factors are responsible for the absence of secondary oscillations found for cosmic strings. Within this general analysis we finally consider the conditions under which topological defects and inflation can be confused. It is argued that only \\Omega=1 inflation and a defect with a horizon size coherence length have a chance to be confused. Any other inflationary or defect model always differ distinctly. (To appear in the proceedings of the XXXIth Moriond meeting, ``Microwave Background Anisotropies'')

  3. DC coupled Doppler radar physiological monitor.

    Science.gov (United States)

    Zhao, Xi; Song, Chenyan; Lubecke, Victor; Boric-Lubecke, Olga

    2011-01-01

    One of the challenges in Doppler radar systems for physiological monitoring is a large DC offset in baseband outputs. Typically, AC coupling is used to eliminate this DC offset. Since the physiological signals of interest include frequency content near DC, it is not desirable to simply use AC coupling on the radar outputs. While AC coupling effectively removes DC offset, it also introduces a large time delay and distortion. This paper presents the first DC coupled IQ demodulator printed circuit board (PCB) design and measurements. The DC coupling is achieved by using a mixer with high LO to RF port isolation, resulting in a very low radar DC offset on the order of mV. The DC coupled signals from the PCB radar system were successfully detected with significant LNA gain without saturation. Compared to the AC coupled results, the DC coupled results show great advantages of less signal distortion and more accurate rate estimation. PMID:22254704

  4. Doppler cooling and trapping on forbidden transitions.

    Science.gov (United States)

    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.

  5. Microscale Heat Conduction Models and Doppler Feedback

    Energy Technology Data Exchange (ETDEWEB)

    Hawari, Ayman I. [North Carolina State Univ., Raleigh, NC (United States); Ougouag, Abderrafi [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-01-22

    The objective of this project is to establish an approach for providing the fundamental input that is needed to estimate the magnitude and time-dependence of the Doppler feedback mechanism in Very High Temperature reactors. This mechanism is the foremost contributor to the passive safety of gas-cooled, graphite-moderated high temperature reactors that use fuel based on Tristructural-Isotropic (TRISO) coated particles. Therefore, its correct prediction is essential to the conduct of safety analyses for these reactors. Since the effect is directly dependent on the actual temperature reached by the fuel during transients, the underlying phenomena of heat deposition, heat transfer and temperature rise must be correctly predicted. To achieve the above objective, this project will explore an approach that accounts for lattice effects as well as local temperature variations and the correct definition of temperature and related local effects.

  6. Correlation and Sequential Filtering with Doppler Measurements

    Institute of Scientific and Technical Information of China (English)

    WANGJianguo; HEPeikun; HANYueqiu; WUSiliang

    2004-01-01

    Two sequential filters are developed for Doppler radar measurements in the presence of correlation between range and range rate measurement errors. Two ideal linear measurement equations with the pseudo measurements are constructed via block-partitioned Cholesky factorization and the practical measurement equationswith the pseudo measurements are obtained through the direction cosine estimation and error compensation. The resulting sequential filters make the position measurement be possibly processed before the pseudo measurement and hence the more accurate direction cosine estimate can be obtained from the filtered position estimate rather than the predicted state estimate. The numerical simulations with different rangerange rate correlation coefficients show thatthe proposed two sequential filters are almost equivalent in performance but both superior to the conventional extended Kalman filter for different correlation coefficients.

  7. Role of transcranial Doppler in cerebrovascular disease.

    Science.gov (United States)

    Kulkarni, Amit A; Sharma, Vijay K

    2016-01-01

    Transcranial Doppler (TCD) is the only noninvasive modality for the assessment of real-time cerebral blood flow. It complements various anatomic imaging modalities by providing physiological-flow related information. It is relatively cheap, easily available, and can be performed at the bedside. It has been suggested as an essential component of a comprehensive stroke centre. In addition to its importance in acute cerebrovascular ischemia, its role is expanding in the evaluation of cerebral hemodynamics in various disorders of the brain. The "established" clinical indications for the use of TCD include cerebral ischemia, sickle cell disease, detection of right-to-left shunts, subarachnoid hemorrhage, periprocedural or surgical monitoring, and brain death. We present the role of TCD in acute cerebrovascular ischemia, sonothrombolysis, and intracranial stenosis. PMID:27625245

  8. Multi-bearing defect detection with trackside acoustic signal based on a pseudo time-frequency analysis and Dopplerlet filter

    Science.gov (United States)

    Zhang, Haibin; Lu, Siliang; He, Qingbo; Kong, Fanrang

    2016-03-01

    The diagnosis of train bearing defects based on the acoustic signal acquired by a trackside microphone plays a significant role in the transport system. However, the wayside acoustic signal suffers from the Doppler distortion due to the high moving speed and also contains the multi-source signals from different train bearings. This paper proposes a novel solution to overcome the two difficulties in trackside acoustic diagnosis. In the method a pseudo time-frequency analysis (PTFA) based on an improved Dopplerlet transform (IDT) is presented to acquire the time centers for different bearings. With the time centers, we design a series of Dopplerlet filters (DF) in time-frequency domain to work on the signal's time-frequency distribution (TFD) gained by the short time Fourier transform (STFT). Then an inverse STFT (ISTFT) is utilized to get the separated signals for each sound source which means bearing here. Later the resampling method based on certain motion parameters eliminates the Doppler Effect and finally the diagnosis can be made effectively according to the envelope spectrum of each separated signal. With the effectiveness of the technique validated by both simulated and experimental cases, the proposed wayside acoustic diagnostic scheme is expected to be available in wayside defective bearing detection.

  9. Application of wavelet analysis in laser Doppler vibration signal denoising

    Science.gov (United States)

    Lan, Yu-fei; Xue, Hui-feng; Li, Xin-liang; Liu, Dan

    2010-10-01

    Large number of experiments show that, due to external disturbances, the measured surface is too rough and other factors make use of laser Doppler technique to detect the vibration signal contained complex information, low SNR, resulting in Doppler frequency shift signals unmeasured, can not be demodulated Doppler phase and so on. This paper first analyzes the laser Doppler signal model and feature in the vibration test, and studies the most commonly used three ways of wavelet denoising techniques: the modulus maxima wavelet denoising method, the spatial correlation denoising method and wavelet threshold denoising method. Here we experiment with the vibration signals and achieve three ways by MATLAB simulation. Processing results show that the wavelet modulus maxima denoising method at low laser Doppler vibration SNR, has an advantage for the signal which mixed with white noise and contained more singularities; the spatial correlation denoising method is more suitable for denoising the laser Doppler vibration signal which noise level is not very high, and has a better edge reconstruction capacity; wavelet threshold denoising method has a wide range of adaptability, computational efficiency, and good denoising effect. Specifically, in the wavelet threshold denoising method, we estimate the original noise variance by spatial correlation method, using an adaptive threshold denoising method, and make some certain amendments in practice. Test can be shown that, compared with conventional threshold denoising, this method is more effective to extract the feature of laser Doppler vibration signal.

  10. Limits on Planetary Companions from Doppler Surveys of Nearby Stars

    Science.gov (United States)

    Howard, Andrew W.; Fulton, Benjamin J.

    2016-11-01

    Most of our knowledge of planets orbiting nearby stars comes from Doppler surveys. For spaced-based, high-contrast imaging missions, nearby stars with Doppler-discovered planets are attractive targets. The known orbits tell imaging missions where and when to observe, and the dynamically determined masses provide important constraints for the interpretation of planetary spectra. Quantifying the set of planet masses and orbits that could have been detected will enable more efficient planet discovery and characterization. We analyzed Doppler measurements from Lick and Keck Observatories by the California Planet Survey. We focused on stars that are likely targets for three space-based planet imaging mission concepts studied by NASA—WFIRST-AFTA, Exo-C, and Exo-S. The Doppler targets are primarily F8 and later main sequence stars, with observations spanning 1987-2014. We identified 76 stars with Doppler measurements from the prospective mission target lists. We developed an automated planet search and a methodology to estimate the pipeline completeness using injection and recovery tests. We applied this machinery to the Doppler data and computed planet detection limits for each star as a function of planet minimum mass and semimajor axis. For typical stars in the survey, we are sensitive to approximately Saturn-mass planets inside of 1 au, Jupiter-mass planets inside of ˜3 au, and our sensitivity declines out to ˜10 au. For the best Doppler targets, we are sensitive to Neptune-mass planets in 3 au orbits. Using an idealized model of Doppler survey completeness, we forecast the precision of future surveys of non-ideal Doppler targets that are likely targets of imaging missions. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by NASA, the University of California, and the University of Hawaii.

  11. Pulsed Doppler echocardiographic analysis of mitral regurgitation after myocardial infarction.

    Science.gov (United States)

    Loperfido, F; Biasucci, L M; Pennestri, F; Laurenzi, F; Gimigliano, F; Vigna, C; Rossi, E; Favuzzi, A; Santarelli, P; Manzoli, U

    1986-10-01

    In 72 patients with previous myocardial infarction (MI), mitral regurgitation (MR) was assessed by pulsed-wave Doppler echocardiography and compared with physical and 2-dimensional echocardiographic findings. MR was found by Doppler in 29 of 42 patients (62%) with anterior MI, 11 of 30 (37%) with inferior MI (p less than 0.01) and in none of 20 normal control subjects. MR was more frequent in patients who underwent Doppler study 3 months after MI than in those who underwent Doppler at discharge (anterior MI = 83% vs 50%, p less than 0.01; inferior MI = 47% vs 27%, p = not significant). Of 15 patients who underwent Doppler studies both times, 3 (all with anterior MI) had MR only on the second study. Of the patients with Doppler MR, 12 of 27 (44%) with a left ventricular (LV) ejection fraction (EF) greater than 30% and 1 of 13 (8%) with an EF of 30% or less (p less than 0.01) had an MR systolic murmur. Mitral prolapse or eversion and papillary muscle fibrosis were infrequent in MI patients, whether or not Doppler MR was present. The degree of Doppler MR correlated with EF (r = -0.61), LV systolic volume (r = 0.47), and systolic and diastolic mitral anulus circumference (r = 0.52 and 0.51, respectively). Doppler MR was present in 24 of 28 patients (86%) with an EF of 40% or less and in 16 of 44 (36%) with EF more than 40% (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3766410

  12. Features of Propagation of the Acoustic-Gravity Waves Generated by High-Power Periodic Radiation

    Science.gov (United States)

    Chernogor, L. F.; Frolov, V. L.

    2013-09-01

    We present the results of the bandpass filtering of temporal variations of the Doppler frequency shift of radio signals from a vertical-sounding Doppler radar located near the city of Kharkov when the ionosphere was heated by high-power periodic (with 10 and 15-min periods) radiation from the Sura facility. The filtering was done in the ranges of periods that are close to the acoustic cutoff period and the Brunt—Väisälä period (4-6, 8-12, and 13-17 min). Oscillations with periods of 4-6 min and amplitudes of 50-100 mHz were not recorded in fact. Oscillations with periods of 8-12 and 13-17 min and amplitudes of 60-100 mHz were detected in almost all the sessions. In the former and the latter oscillations, the time of delay with respect to the heater switch-on was close to 100 min and about 40-50 min, respectively. These values correspond to group propagation velocities of about 160 and 320-400 m/s. The Doppler shift oscillations were caused by the acoustic-gravity waves which led to periodic variations in the electron number density with a relative amplitude of about 0.1-1.0%. It was demonstrated that the acoustic-gravity waves were not recorded when the effective power of the Sura facility was equal to 50 MW and they were confidently observed when the effective power was increased up to 130 MW. It is shown that the period of the wave processes was determined by the period of the heating-pause cycles, and the duration of the wave trains did not depend on the duration of the series of heating-pause cycles. The data suggest that the generation mechanism of recorded wave disturbances is different from the mechanism proposed in 1970-1990.

  13. 长时延环境下多普勒频偏估计与补偿技术%Wideband Doppler estimation and compensation in long-delay channels

    Institute of Scientific and Technical Information of China (English)

    王炜; 钱良; 杨峰; 周卫星

    2012-01-01

    长时延信道模型中相对多普勒频偏比一般的无线信道要大若干个数量级.典型的长时延信道有:水声信道,卫星通信信道等.水声信道中多普勒频偏不仅表现在频域上,还表现在时域上的压缩和扩展.文中对水声OFDM系统中宽带多普勒频偏提出了估计与补偿算法,可以有效消除宽带多普勒频偏的影响.%The Doppler effect is much server in the long-delay channels, such as underwater acoustic channels and satellite communication channels. The Doppler effects in the underwater acoustic channels not only leads to the frequency offset, but also the compression or expansion in the time scale. A method of wideband Doppler estimation and compensation in the OFDM underwater acoustic system is proposed in this paper.

  14. Carotid Doppler and transcranial Doppler in diagnosing transient ischemic attack: A healthy control

    Institute of Scientific and Technical Information of China (English)

    Huiling Chen; Jinhua Qiu; Hongying Liu

    2006-01-01

    BACKGROUND: If changes of hemodynamics in internal or external cranial artery and stenosis of atherosclerosis are found early, patients with transient ischemic attack (TIA) may be treated at an early phase so as to prevent and decrease the onset of cerebral infarction. Carotid Doppler can analyze carotid canal wall, hemodynamic properties and stenosis, and changes of plaque morphology; however, transcranial Doppler (TCD)can evaluate vascular stenosis and occlusion and judge collateral circulation in cranium through detecting velocity and direction of blood flow. Can the association of them increase the diagnostic rate of TIA?OBJECTIVE: To evaluate the effect of the association of carotid Doppler and TCD on TIA in internal carotid artery.DESIGN: Contrast observational study.SETTING: Department of Neuroelectrophysiology, Central People's Hospital of Huizhou.PARTICIPANTS: A total of 54 patients with TIA in internal carotid artery were selected from the Department of Neurology of Huizhou Central People's Hospital from May 2004 to June 2005. There were 35 males and 24 females aged 46-81 years. The clinical situation was asthenia of single limb, hemiplegia, anaesthesia of single upper or lower limb, hemianesthesia, sensory disorder and aphasia. The symptoms lasted for less than 2 hours. All cases were diagnosed with CT, and those who had pathological changes of acute cerebral infarction and history of cardiac disease were excluded. Additionally, 50 healthy subjects who were regarded as control group were selected from the Department of Neurology of Huizhou Central People's Hospital. There were 30 males and 20 females aged 45-80 years. All subjects were consent.METHODS: HD15000 color Doppler ultrasound (Philips Company, USA) and Muliti-DopX2 TCD (DWL Company, Germany) were used to detect hemodynamics, stenosis and distribution of atherosclerosis in carotid artery and internal carotid artery. Evaluation of marker: Stenosis was calculated by the ratio between the minimal

  15. Phase modulation of propagation effect with Doppler broadening

    Institute of Scientific and Technical Information of China (English)

    Qiao Hong-Xia; Yang Yan-Ling; Tan Xia; Tong Dian-Min; Fan Xi-Jun

    2008-01-01

    This paper studies the propagation effect in a closed lambda-type three-level atomic system with Doppler broadening.It is shown that,Doppler broadening due to atomic motion and propagation effect associated with driving field depletion along the active medium decreases obviously the gain and output of the lasing without inversion(LWI);the relative phase between the probe and driving fields has a remarkable modulation role to the propagation effect on LWI when Doppler broadening presents;by choosing suitable value of the relative phase,we can get the largest gain and output of LWI.

  16. Interferometric millimeter wave and THz wave doppler radar

    Science.gov (United States)

    Liao, Shaolin; Gopalsami, Nachappa; Bakhtiari, Sasan; Raptis, Apostolos C.; Elmer, Thomas

    2015-08-11

    A mixerless high frequency interferometric Doppler radar system and methods has been invented, numerically validated and experimentally tested. A continuous wave source, phase modulator (e.g., a continuously oscillating reference mirror) and intensity detector are utilized. The intensity detector measures the intensity of the combined reflected Doppler signal and the modulated reference beam. Rigorous mathematics formulas have been developed to extract bot amplitude and phase from the measured intensity signal. Software in Matlab has been developed and used to extract such amplitude and phase information from the experimental data. Both amplitude and phase are calculated and the Doppler frequency signature of the object is determined.

  17. Computer simulation studies of pulsed Doppler signals from vortices

    Institute of Scientific and Technical Information of China (English)

    CHEN Sizhong; WANG Yuanyuan; WANG Weiqi

    2001-01-01

    A computer simulation method for pulsed Doppler signals from vortices was proposed to generate simulated vortex Doppler signals under various given circumstances. The relative waveforms, such as the maximum frequency waveform, the mean frequency waveform and the bandwidth waveform, were obtained using the short time Fourier analysis of those simulated signals. The relations were studied between several spectrum parameters obtained from these waveforms and given simulation conditions, such as the position and the size of the sample volume, the distance between two vortices, the free stream velocity and the maximum tangent velocity of the vortex. The sensitive parameters were found to detect vortices using the pulsed Doppler techniques.

  18. Coherent Doppler wind lidars in a turbulent atmosphere

    CERN Document Server

    Banakh, Viktor

    2013-01-01

    Radiophysical tools for measuring atmospheric dynamics include sodars, Doppler radars, and Doppler lidars. Among these, coherent Doppler lidars (CDLs) have been considered the best for remote measurement of wind turbulence. This is important not only for understanding the exchange processes in the boundary layer, but also in the applied aspect, such as aviation safety. CDLs significantly extend possibilities of experimental investigation of not only wind turbulence, but also coherent structures such as aircraft wake vortices. The authors of this book conducted field tests of the developed meth

  19. Sub-Doppler laser cooling of potassium atoms

    CERN Document Server

    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

    Energy Technology Data Exchange (ETDEWEB)

    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.