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Sample records for doppler shift method

  1. Ultrasonic distance and velocity measurement using a pair of LPM signals for cross-correlation method: improvement of Doppler-shift compensation and examination of Doppler velocity estimation.

    PubMed

    Hirata, Shinnosuke; Kurosawa, Minoru Kuribayashi

    2012-09-01

    Real-time distance measurement of a moving object with high accuracy and high resolution using an ultrasonic wave is difficult due to the influence of the Doppler effect or the limit of the calculation cost of signal processing. An over-sampling signal processing method using a pair of LPM signals has been proposed for ultrasonic distance and velocity measurement of moving objects with high accuracy and high resolution. The proposed method consists of cross correlation by single-bit signal processing, high-resolution Doppler velocity estimation with wide measurement range and low-calculation-cost Doppler-shift compensation. The over-sampling cross-correlation function is obtained from cross correlation by single-bit signal processing with low calculation cost. The Doppler velocity and distance of the object are determined from the peak interval and peak form in the cross-correlation function by the proposed method of Doppler velocity estimation and Doppler-shift compensation. In this paper, the proposed method of Doppler-shift compensation is improved. Accuracy of the determined distance was improved from approximately within ±140μm in the previous method to approximately within ±10μm in computer simulations. Then, the proposed method of Doppler velocity estimation is evaluated. In computer simulations, accuracy of the determined Doppler velocity and distance were demonstrated within ±8.471mm/s and ±13.87μm. In experiments, Doppler velocities of the motorized stage could be determined within ±27.9mm/s. PMID:22560801

  2. Fabrication of 94Zr thin target for recoil distance doppler shift method of lifetime measurement

    NASA Astrophysics Data System (ADS)

    Gupta, C. K.; Rohilla, Aman; Abhilash, S. R.; Kabiraj, D.; Singh, R. P.; Mehta, D.; Chamoli, S. K.

    2014-11-01

    A thin isotopic 94Zr target of thickness 520 μg /cm2 has been prepared for recoil distance Doppler shift method (RDM) lifetime measurement by using an electron beam deposition method on tantalum backing of 3.5 mg/cm2 thickness at Inter University Accelerator Center (IUAC), New Delhi. To meet the special requirement of smoothness of surface for RDM lifetime measurement and also to protect the outer layer of 94Zr from peeling off, a very thin layer of gold has been evaporated on a 94Zr target on a specially designed substrate holder. In all, 143 mg of 99.6% enriched 94Zr target material was utilized for the fabrication of 94Zr targets. The target has been successfully used in a recent RDM lifetime measurement experiment at IUAC.

  3. Lifetime measurement of 2+- state in 74Zn by recoil-distance Doppler-shift method

    NASA Astrophysics Data System (ADS)

    Niikura, M.; Mouginot, B.; Azaiez, F.; Franchoo, S.; Matea, I.; Stefan, I.; Verney, D.; Assie, M.; Bednarczyk, P.; Borcea, C.; Burger, A.; Burgunder, G.; Buta, A.; Cáceres, L.; Cléement, E.; Coquard, L.; de Angelis, G.; de France, G.; de Oliveira Santos, F.; Dewald, A.; Dijon, A.; Dombradi, Z.; Fiori, E.; Fransen, C.; Friessner, G.; Gaudefroy, L.; Georgiev, G.; Grévy, S.; Hackstein, M.; Harakeh, M. N.; Ibrahim, F.; Kamalou, O.; Kmiecik, M.; Lozeva, R.; Maj, A.; Mihai, C.; Möller, O.; Myalski, S.; Negoita, F.; Pantelica, D.; Perrot, L.; Pissulla, Th.; Rotaru, F.; Rother, W.; Scarpaci, J. A.; Stodel, C.; Thomas, J. C.; Ujic, P.

    2013-09-01

    We have performed the first direct lifetime measurement of the 2+- state in 74Zn. The neutron-rich 74Zn beam was produced by in-flight fragmentation of 76Ge at the Grand Accélérateur National d'Ions Lourds and separated with the LISE spectrometer. The lifetime of the 2+- state was measured by the recoil-distance Doppler-shift method with the Cologne plunger device combined with the EXOGAM detectors. The lifetime of the 2+- state in 74Zn was determined to be 27.0(24) ps, which corresponds to a reduced transition probability B(E2; 2+- -> 0+) = 370(33) e2fm4.

  4. Mitigating Doppler shift effect in HF multitone data modem

    NASA Astrophysics Data System (ADS)

    Sonlu, Yasar

    1989-09-01

    Digital communications over High Frequency (HF) radio channels are getting important in recent years. Current HF requirements are for data transmission at rates 2.4 kbps or more to accommodate computer data links and digital secure voice. HF modems which were produced to meet these speeds are, serial modems and parallel modems. On the other hand, the HF sky-wave communication medium, the ionosphere, has some propagation problems such as multipath and Doppler shift. The effect of Doppler shift in a parallel modem which employs Differential Quadrature Phase Shift Keying (DQPSK) modulation is considered and a correction method to mitigate the Doppler Shift effect is introduced.

  5. The Novel Nonlinear Adaptive Doppler Shift Estimation Technique and the Coherent Doppler Lidar System Validation Lidar

    NASA Technical Reports Server (NTRS)

    Beyon, Jeffrey Y.; Koch, Grady J.

    2006-01-01

    The signal processing aspect of a 2-m wavelength coherent Doppler lidar system under development at NASA Langley Research Center in Virginia is investigated in this paper. The lidar system is named VALIDAR (validation lidar) and its signal processing program estimates and displays various wind parameters in real-time as data acquisition occurs. The goal is to improve the quality of the current estimates such as power, Doppler shift, wind speed, and wind direction, especially in low signal-to-noise-ratio (SNR) regime. A novel Nonlinear Adaptive Doppler Shift Estimation Technique (NADSET) is developed on such behalf and its performance is analyzed using the wind data acquired over a long period of time by VALIDAR. The quality of Doppler shift and power estimations by conventional Fourier-transform-based spectrum estimation methods deteriorates rapidly as SNR decreases. NADSET compensates such deterioration in the quality of wind parameter estimates by adaptively utilizing the statistics of Doppler shift estimate in a strong SNR range and identifying sporadic range bins where good Doppler shift estimates are found. The authenticity of NADSET is established by comparing the trend of wind parameters with and without NADSET applied to the long-period lidar return data.

  6. Current-induced spin wave Doppler shift

    NASA Astrophysics Data System (ADS)

    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).

  7. Solar Doppler shifts - Sources of continuous spectra

    NASA Technical Reports Server (NTRS)

    Duvall, T. L., Jr.; Harvey, J. W.

    1986-01-01

    Oscillation observations can be used to study nonoscillatory solar phenomena that exhibit Doppler shifts. The paper discusses several effects of these phenomena and their associated temporal and spatial power spectra: (1) they limit the signal-to-noise ratio and sometimes detectability of oscillation modes; (2) there is the potential for better understanding and/or detection of solar phenomena; (3) large-scale convection may spatially modulate oscillation modes, leading to a continuous background spectrum; and (4) in regions of the spectrum where the resolution to separate modes is lacking one can determine upper limits for the integrated effects of modes.

  8. Using Doppler Shifts of GPS Signals To Measure Angular Speed

    NASA Technical Reports Server (NTRS)

    Campbell, Charles E., Jr.

    2006-01-01

    A method has been proposed for extracting information on the rate of rotation of an aircraft, spacecraft, or other body from differential Doppler shifts of Global Positioning System (GPS) signals received by antennas mounted on the body. In principle, the method should be capable of yielding low-noise estimates of rates of rotation. The method could eliminate the need for gyroscopes to measure rates of rotation. The method is based on the fact that for a given signal of frequency ft transmitted by a given GPS satellite, the differential Doppler shift is attributable to the difference between those components of the instantaneous translational velocities of the antennas that lie along the line of sight from the antennas to the GPS satellite.

  9. Active Region Moss: Doppler Shifts from Hinode/EIS Observations

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2012-01-01

    Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Hinode on 12-Dec- 2007 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low density cut-off as derived by Tripathi et al. (2010). We have carried out a very careful analysis of the EIS wavelength calibration based on the method described in Young, O Dwyer and Mason (2012). For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km/s with an estimated error of 4 km/s. The width of the distribution decreases with temperature. The mean of the distribution shows a blue shift which increases with increasing temperature and the distribution also shows asymmetries towards blue-shift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. Further observational constraints are needed to distinguish between these two heating scenarios.

  10. Spread-Spectrum Carrier Estimation With Unknown Doppler Shift

    NASA Technical Reports Server (NTRS)

    DeLeon, Phillip L.; Scaife, Bradley J.

    1998-01-01

    We present a method for the frequency estimation of a BPSK modulated, spread-spectrum carrier with unknown Doppler shift. The approach relies on a classic periodogram in conjunction with a spectral matched filter. Simulation results indicate accurate carrier estimation with processing gains near 40. A DSP-based prototype has been implemented for real-time carrier estimation for use in New Mexico State University's proposal for NASA's Demand Assignment Multiple Access service.

  11. Quantitative Measurement of the Doppler Shift at an Ultrasonic Frequency

    ERIC Educational Resources Information Center

    Nerbun, R. C.; Leskovec, R. A.

    1976-01-01

    Discussed is a Doppler shift laboratory experiment for an introductory college physics course. Ultrasonic transducers and a digital phase detector circuit "black box" are used to overcome room noise and "standing waves" and to produce an observable frequency shift. (SL)

  12. C IV Doppler shifts observed in active region filaments

    NASA Technical Reports Server (NTRS)

    Klimchuk, J. A.

    1986-01-01

    The Doppler shift properties of 21 active region filaments were studied using C IV Dopplergram data. Most are associated with corridors of weak magnetic field that separate opposite polarity strong fields seen in photospheric magnetograms. A majority of the filaments are relatively blue shifted, although several lie very close to the dividing lines between blue and red shift. Only one filament in the samples is clearly red shifted. A new calibration procedure for Dopplergrams indicates that sizable zero point offsets are often required. The center-to-limb behavior of the resulting absolute Doppler shifts suggests that filament flows are usually quite small. It is possible that they vanish.

  13. Modeling of Doppler frequency shift in multipath radiochannels

    NASA Astrophysics Data System (ADS)

    Penzin, Maksim; Iyin, Nikolay

    2016-06-01

    We discuss the modeling of propagation of a quasi-monochromatic radio signal, represented by a coherent pulse sequence, in a non-stationary multipath radio channel. In such a channel, signal propagation results in the observed frequency shift for each ray (Doppler effect). The modeling is based on the assumption that during propagation of a single pulse a channel can be considered stationary. A phase change in the channel transfer function is shown to cause the observed frequency shift in the received signal. Thus, instead of measuring the Doppler frequency shift, we can measure the rate of change in the mean phase of one pulse relative to another. The modeling is carried out within the framework of the method of normal waves. The method enables us to model the dynamics of the electromagnetic field at a given point with the required accuracy. The modeling reveals that a local change in ionospheric conditions more severely affects the rays whose reflection region is in the area where the changes occur.

  14. Compression of polyphase codes with Doppler shift

    NASA Astrophysics Data System (ADS)

    Wirth, W. D.

    It is shown that pulse compression with sufficient Doppler tolerance may be achieved with polyphase codes derived from linear frequency modulation (LFM) and nonlinear frequency modulation (NLFM). Low sidelobes in range and Doppler are required especially for the radar search function. These may be achieved by an LFM derived phase coder together with Hamming weighting or by applying a PNL polyphase code derived from NLFM. For a discrete and known Doppler frequency with an expanded and mismatched reference vector a sidelobe reduction is possible. The compression is then achieved without a loss in resolution. A set up for the expanded reference gives zero sidelobes only in an interval around the signal peak or a least square minimization for all range elements. This version may be useful for target tracking.

  15. Global Doppler frequency shift detection with near-resonant interferometry

    NASA Astrophysics Data System (ADS)

    Landolt, Andrin; Roesgen, Thomas

    2009-10-01

    The recent development in measuring 2D Doppler shift distributions for flow velocimetry using the dispersive properties of atomic line filters is presented. On the basis of velocity field measurements on a subsonic jet flow and a tip vortex flow in a medium-sized wind tunnel, the technique was assessed. Atomic line filters near a resonant transition combine imaging capabilities with a sharp frequency cutoff and an associated region of strong anomalous dispersion. While conventional Doppler global velocimetry relies on the absorption of the filter to convert frequency shifts to intensity variations, near-resonant interferometry uses its dispersion to detect frequency shifts as phase changes in an interference pattern. In the present setup, an iodine vapor cell in an imaging Michelson interferometer is used. With the illuminating laser frequency tuned near a resonant transition, the cell’s dispersion converts the frequency content of the field of view into a distortion of the carrier-fringe pattern recorded at the image plane of the interferometer. The phase distribution in the fringe images is reconstructed by filtering the individual images with a 2D Gabor filter pair tuned to the spatial frequencies of the basic carrier-fringe pattern. The post-processing is concluded with subsequent phase-unwrapping and subtraction of the carrier reference fringe phase. The method and the setup were demonstrated and calibrated experimentally on a rotating disc. The capability of the technique to operate in a real experimental environment was validated in a free subsonic jet and a tip vortex flow behind a wing section in a medium-sized wind tunnel facility. The measurements were found to be in generally good agreement with the theoretically predicted system characteristics and the reference measurements. As with other Doppler global techniques, the stability of the pulsed laser system and the secondary scattering in the test volume were identified as the main error sources.

  16. Apparatus and method for noninvasive particle detection using doppler spectroscopy

    DOEpatents

    Sinha, Dipen N.

    2016-05-31

    An apparatus and method for noninvasively detecting the presence of solid particulate matter suspended in a fluid flowing through a pipe or an oil and gas wellbore are described. Fluid flowing through a conduit containing the particulate solids is exposed to a fixed frequency (>1 MHz) of ultrasonic vibrations from a transducer attached to the outside of the pipe. The returning Doppler frequency shifted signal derived from the scattering of sound from the moving solid particles is detected by an adjacent transducer. The transmitted signal and the Doppler signal are combined to provide sensitive particulate detection. The magnitude of the signal and the Doppler frequency shift are used to determine the particle size distribution and the velocity of the particles. Measurement of the phase shift between the applied frequency and the detected Doppler shifted may be used to determine the direction of motion of the particles.

  17. Graphical Representation of the Doppler Shift: Classical and Relativistic

    ERIC Educational Resources Information Center

    Rojas, R.; Fuster, G.

    2007-01-01

    The Doppler shift is a frequency change of a repetitive effect, as measured by a receiver, due to the motion of the wave emitter, to the motion of the wave receiver, or both. A demonstration of the effect is provided by the sound of a car's horn that changes from a higher pitch to a lower pitch when a car drives past. Most derivations of the…

  18. Doppler-shifted self-reflected wave from a semiconductor

    NASA Astrophysics Data System (ADS)

    Schuelzgen, Alex; Hughes, S.; Peyghambarian, Nasser

    1997-06-01

    We report the first experimental observation of a self- reflected wave inside a very dense saturable absorber. An intense femtosecond pulse saturates the absorption and causes a density front moving into the semiconductor sample. Due to the motion of the boundary between saturated and unsaturated areas of the sample the light reflected at this boundary is red-shifted by the Doppler effect. The spectrally shifted reflection makes it possible to distinguish between surface reflection and self-reflection and is used to proof the concept of the dynamic nonlinear skin effect experimentally. Quite well agreement with model calculations is found.

  19. Method for Canceling Ionospheric Doppler Effect

    NASA Technical Reports Server (NTRS)

    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.

  20. Current-induced spin-wave Doppler shift.

    PubMed

    Vlaminck, Vincent; Bailleul, Matthieu

    2008-10-17

    Spin transfer appears to be a promising tool for improving spintronics devices. Experiments that quantitatively access the magnitude of the spin transfer are required for a fundamental understanding of this phenomenon. By inductively measuring spin waves propagating along a permalloy strip subjected to a large electrical current, we observed a current-induced spin wave Doppler shift that we relate to the adiabatic spin transfer torque. Because spin waves provide a well-defined system for performing spin transfer, we anticipate that they could be used as an accurate probe of spin-polarized transport in various itinerant ferromagnets. PMID:18927387

  1. Magnetic Compensation for Second-Order Doppler Shift in LITS

    NASA Technical Reports Server (NTRS)

    Burt, Eric; Tjoelker, Robert

    2008-01-01

    The uncertainty in the frequency of a linear-ion-trap frequency standard (LITS) can be reduced substantially by use of a very small magnetic inhomogeneity tailored to compensate for the residual second-order Doppler shift. An effect associated with the relativistic time dilatation, one cause of the second-order Doppler shift, is ion motion that is attributable to the trapping radio-frequency (RF)electromagnetic field used to trap ions. The second-order Doppler shift is reduced by using a multi-pole trap; however it is still the largest source of systematic frequency shift in the latest generation of LITSs, which are among the most stable clocks in the world. The present compensation scheme reduces the frequency instability of the affected LITS to about a tenth of its previous value. The basic principles of prior generation LITSs were discussed in several prior NASA Tech Briefs articles. Below are recapitulated only those items of basic information necessary to place the present development in context. A LITS includes a microwave local oscillator, the frequency of which is stabilized by comparison with the frequency of the ground state hyperfine transition of 199Hg+ ions. The comparison involves a combination of optical and microwave excitation and interrogation of the ions in a linear ion trap in the presence of a nominally uniform magnetic field. In the current version of the LITS, there are two connected traps (see figure): (1) a quadrupole trap wherein the optical excitation and measurement take place and (2) a 12-pole trap (denoted the resonance trap), wherein the microwave interrogation takes place. The ions are initially loaded into the quadrupole trap and are thereafter shuttled between the two traps. Shuttling ions into the resonance trap allows sensitive microwave interrogation to take place well away from loading interference. The axial magnetic field for the resonance trap is generated by an electric current in a finely wound wire coil surrounded by

  2. Solar Doppler-shift measurements in the Ne VII 465 A emission line

    NASA Technical Reports Server (NTRS)

    Mariska, John T.; Dowdy, James F., Jr.

    1992-01-01

    Using a Dopplergram obtained with the Naval Research Laboratory extreme ultraviolet spectrograph on Skylab, we have searched for Doppler shifts in the Ne VII 465 A emission line, which is formed at a temperature of about 500,000 K. In the quiet sun we find no measurable average Doppler shift to a measurement accuracy of +/- 18 km/s. Small regions of the quiet sun do, however, display measurable Doppler shifts. In active regions, we measure Doppler shifts indicating downflow velocities of up to 70 km/s.

  3. Magnetic flux cancellation and Doppler shifts in flaring active regions

    NASA Astrophysics Data System (ADS)

    Burtseva, Olga; Petrie, Gordon

    2016-05-01

    Flux cancellation plays an important role in some theories of solar eruptions. The mechanism of flux cancellation is suggested by many models to be a necessary condition of flare initiation as a part of slow reconnection processes in the lower atmosphere. In our earlier work we analyzed flux cancellation events during major flares using GONG line-of-sight magnetograms. In this work we use vector magnetic field data from SDO/HMI for better interpretation of the longitudinal field changes. We also compute Doppler velocity shifts at the cancellation sites in attempt to distinguish between the three physical processes that could stand behind flux removal from the photosphere: submergence of U-shaped loops, emergence of Ω-shaped loops and magnetic reconnection.

  4. Doppler-Shifted Flare Emissions Observed by SDO/EVE

    NASA Technical Reports Server (NTRS)

    Chamberlin, Phillip C.

    2012-01-01

    The EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO) has been obtaining unprecedented observations of solar variation on times scales of seconds during flares and over the rising phase of Solar Cycle 24 since its start of normal operations in May 2010. Unexpectedly, as first pointed out in Hudson et. al., Ap.j. (2011), even with EVE's spectral resolution of 0.1 nm and 'irradiance' measurements, EVE has the ability to very accurately determine Doppler shifts in all emissions during solar flares and coronal mass ejections (CMEs). The technique for deriving these absolute velocities is not straightforward, as the optical and instrumental effects must first be eliminated in order to separate the absolute plasma velocities from the instrument effects. This talk will discuss these efforts to eliminate the instrumental component, as well as show some of the first results of absolute velocities of multiple emissions at a wide range of temperatures during solar flares.

  5. Doppler-shifted reflections of X rays in beamfoil spectroscopy

    NASA Technical Reports Server (NTRS)

    Bernstein, E. M.; Mcintyre, L. C., Jr.

    1976-01-01

    Carbon foils were positioned at roughly 10 deg to the conventional perpendicular position so that the spectrometer would view the beam on emergence from the foil, with no radiation shielded by a bowed or wrinkled foil or by the foil holder. Extraneous peaks due to reflected radiation were detected in the spectrum obtained with the tilted foil. A large satellite appears longward of the spectral line and is attributed to Doppler-shifted radiation reflected from the foil surface. Special tests arranged to validate the origin of the satellites are described. The relative intensity of the reflected radiation compared with the direct radiation observed is at variance with the relative intensities reported for longer wavelengths. The reasons for this, possible effects of spectrometer geometry, and applications in the investigation or generation of polarization remain to be investigated

  6. Wave turbulent diffusion due to the Doppler shift

    NASA Astrophysics Data System (ADS)

    Balk, A. M.

    2006-08-01

    Turbulent diffusion of a passive tracer caused by a random wavefield is believed to be quadratic with respect to the energy spectrum ɛk of the velocity field (i.e. proportional to epsi4, where epsi is the order of the wave amplitudes). So, the wave turbulent diffusion (say, on the ocean surface or in the air) is often believed to be dominated by the turbulent diffusion due to the incompressible flow. In this paper, we show that the wave turbulent diffusion can be associated with the Doppler shift and find that the wave turbulent diffusion can be more significant than previously thought. This mechanism works if the velocity field is compressible and statistically anisotropic, with the result that the wave system has a significant Stokes drift. The contribution of this mechanism has a lower order in epsi. We confirm our results with numerical simulations. To derive these results, we develop the statistical near-identity transformation.

  7. The quiet Sun average Doppler shift of coronal lines up to 2 MK

    NASA Astrophysics Data System (ADS)

    Dadashi, N.; Teriaca, L.; Solanki, S. K.

    2011-10-01

    Context. The average Doppler shift shown by spectral lines formed from the chromosphere to the corona reveals important information on the mass and energy balance of the solar atmosphere, providing an important observational constraint to any models of the solar corona. Previous spectroscopic observations of vacuum ultra-violet (VUV) lines have revealed a persistent average wavelength shift of lines formed at temperatures up to 1 MK. At higher temperatures, the behaviour is still essentially unknown. Aims: Here we analyse combined SUMER (Solar Ultraviolet Measurements of Emitted Radiation)/SoHO (Solar and Heliospheric Observatory) and EIS (EUV Imaging Spectrometer)/Hinode observations of the quiet Sun around disk centre to determine, for the first time, the average Doppler shift of several spectral lines formed between 1 and 2 MK, where the largest part of the quiet coronal emission is formed. Methods: The measurements are based on a novel technique applied to EIS spectra to measure the difference in Doppler shift between lines formed at different temperatures. Simultaneous wavelength-calibrated SUMER spectra allow establishing the absolute value at the reference temperature of T ≈ 1 MK. Results: The average line shifts at 1 MK < T < 1.8 MK are modestly, but clearly bluer than those observed at 1 MK. By accepting an average blue shift of about (-1.8 ± 0.6) km s-1 at 1 MK (as provided by SUMER measurements), this translates into a maximum Doppler shift of (-4.4 ± 2.2) km s-1 around 1.8 MK. The measured value appears to decrease to about (-1.3 ± 2.6) km s-1 at the Fe xv formation temperature of 2.1 MK. Conclusions: The measured average Doppler shift between 0.01 and 2.1 MK, for which we provide a parametrisation, appears to be qualitatively and roughly quantitatively consistent with what foreseen by 3D coronal models where heating is produced by dissipation of currents induced by photospheric motions and by reconnection with emerging magnetic flux.

  8. Servomechanism for Doppler shift compensation in optical correlator for synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Constaninides, N. J.; Bicknell, T. J. (Inventor)

    1980-01-01

    A method and apparatus for correcting Doppler shifts in synthetic aperture radar data is described. An optical correlator for synthetic aperture radar data has a means for directing a laser beam at a signal film having radar return pulse intensity information recorded on it. A resultant laser beam passes through a range telescope, an azimuth telescope, and a Fourier transform filter located between the range and azimuth telescopes, and forms an image for recording on an image film. A compensation means for Doppler shift in the radar return pulse intensity information includes a beam splitter for reflecting the modulated laser beam, after having passed through the Fourier transform filter, to a detection screen having two photodiodes mounted on it.

  9. MOSES Observations of Doppler Shifts in HeII λ304

    NASA Astrophysics Data System (ADS)

    Rust, Thomas; Kankelborg, C.

    2013-07-01

    We report on Doppler shifts observed in HeII λ304 with the Multi-Order Solar EUV Spectrograph (MOSES) sounding rocket. We use wavelet analysis for automated identification and analysis of Doppler shifted emission at different spatial scales, and track the temporal evolution over time of flight.

  10. Distribution of mean Doppler shift, spectral width, and skewness of coherent 50-MHz auroral radar backscatter

    SciTech Connect

    Watermann, J.; McNamara, A.G. ); Sofko, G.J.; Koehler, J.A. )

    1989-06-01

    Some 7,700 radio aurora spectra obtained from a six link 50-MHz CW radar network set up on the Canadian prairies were analyzed with respect to the distributions of mean Doppler shift, spectral width and skewness. A comparison with recently published SABRE results obtained at 153 MHz shows substantial differences in the distributions which are probably due to different experimental and geophysical conditions. The spectra are mostly broad with mean Doppler shifts close to zero (type II spectra). The typical groupings of type I and type III spectra are clearly identified. All types appear to be in general much more symmetric than those recorded with SABRE, and the skewness is only weakly dependent on the sign of the mean Doppler shift. Its distribution peaks near zero and shows a weak positive correlation with the type II Doppler shifts while the mostly positive type I Doppler shifts are slightly negatively correlated with the skewness.

  11. Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage. Either inverse or normal Doppler shift is realized by injecting an external RF signal into the electronically reconfigurable metamaterial, on which an electronically controllable moving reflective boundary is formed. The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit. This work is expected to open up possibilities in applying the inverse Doppler effect in wireless communications, radar and satellite navigation.

  12. The shifted penalty method

    NASA Astrophysics Data System (ADS)

    Zavarise, Giorgio

    2015-07-01

    The method presented here is a variation of the classical penalty one, suited to reduce penetration of the contacting surfaces. The slight but crucial modification concerns the introduction of a shift parameter that moves the minimum point of the constrained potential toward the exact value, without any penalty increase. With respect to the classical augmentation procedures, the solution improvement is embedded within the original penalty contribution. The problem is almost consistently linearized, and the shift is updated before each Newton's iteration. However, adding few iterations, with respect to the original penalty method, a reduction of the penetration of several orders of magnitude can be achieved. The numerical tests have shown very attractive characteristics and very stable solution paths. This permits to foresee a wide area of applications, not only in contact mechanics, but for any problem, like e.g. incompressible materials, where a penalty contribution is required.

  13. Wideband Doppler frequency shift measurement and direction ambiguity resolution using optical frequency shift and optical heterodyning.

    PubMed

    Lu, Bing; Pan, Wei; Zou, Xihua; Yan, Xianglei; Yan, Lianshan; Luo, Bin

    2015-05-15

    A photonic approach for both wideband Doppler frequency shift (DFS) measurement and direction ambiguity resolution is proposed and experimentally demonstrated. In the proposed approach, a light wave from a laser diode is split into two paths. In one path, the DFS information is converted into an optical sideband close to the optical carrier by using two cascaded electro-optic modulators, while in the other path, the optical carrier is up-shifted by a specific value (e.g., from several MHz to hundreds of MHz) using an optical-frequency shift module. Then the optical signals from the two paths are combined and detected by a low-speed photodetector (PD), generating a low-frequency electronic signal. Through a subtraction between the specific optical frequency shift and the measured frequency of the low-frequency signal, the value of DFS is estimated from the derived absolute value, and the direction ambiguity is resolved from the derived sign (i.e., + or -). In the proof-of-concept experiments, DFSs from -90 to 90 kHz are successfully estimated for microwave signals at 10, 15, and 20 GHz, where the estimation errors are lower than ±60  Hz. The estimation errors can be further reduced via the use of a more stable optical frequency shift module. PMID:26393729

  14. Doppler wavelength shifts of ultraviolet spectral lines in solar active regions

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Doschek, G. A.; Cohen, L.

    1982-01-01

    Doppler shifts are measured for solar UV emission lines formed in the lower transition region of active regions. Doppler shifts in different regions at the same solar location, variations of Doppler shift with position of an active region on the disk, and variations of Doppler shift with time at the same solar location in the same active region were studied. Observations were made with the NRL slit spectrograph on Skylab. Excluding flare and flare-related phenomena, only redshifts are found whose magnitudes correspond to downflow velocities between about 4 and 17 km/s. Shifts are largest for lines formed between about 50,000 and 100,000 K, and are distinctly less for lines formed above 100,000 K. The shifts persist out to the limb, but not above it. There is no obvious change in redshift for lines measured at the same solar location over time intervals of about 20 minutes.

  15. Method and apparatus for Doppler frequency modulation of radiation

    NASA Technical Reports Server (NTRS)

    Margolis, J. S.; Mccleese, D. J.; Shumate, M. S.; Seaman, C. H. (Inventor)

    1980-01-01

    A method and apparatus are described for frequency modulating radiation, such as from a laser, for optoacoustic detectors, interferometers, heterodyne spectrometers, and similar devices. Two oppositely reciprocating cats-eye retroreflectors are used to Doppler modulate the radiation. By reciprocally moving both retroreflectors, the center of mass is maintained constant to permit smooth operation at many Hertz. By slightly offsetting the axis of one retroreflector relative to the other, multiple passes of a light beam may be achieved for greater Doppler shifts with the same reciprocating motion of the retroreflectors.

  16. Center of Mass Estimation for a Spinning Spacecraft Using Doppler Shift of the GPS Carrier Frequency

    NASA Technical Reports Server (NTRS)

    Sedlak, Joseph E.

    2016-01-01

    A sequential filter is presented for estimating the center of mass (CM) of a spinning spacecraft using Doppler shift data from a set of onboard Global Positioning System (GPS) receivers. The advantage of the proposed method is that it is passive and can be run continuously in the background without using commanded thruster firings to excite spacecraft dynamical motion for observability. The NASA Magnetospheric Multiscale (MMS) mission is used as a test case for the CM estimator. The four MMS spacecraft carry star cameras for accurate attitude and spin rate estimation. The angle between the spacecraft nominal spin axis (for MMS this is the geometric body Z-axis) and the major principal axis of inertia is called the coning angle. The transverse components of the estimated rate provide a direct measure of the coning angle. The coning angle has been seen to shift slightly after every orbit and attitude maneuver. This change is attributed to a small asymmetry in the fuel distribution that changes with each burn. This paper shows a correlation between the apparent mass asymmetry deduced from the variations in the coning angle and the CM estimates made using the GPS Doppler data. The consistency between the changes in the coning angle and the CM provides validation of the proposed GPS Doppler method for estimation of the CM on spinning spacecraft.

  17. Doppler-shifted neutral beam line shape and beam transmission

    SciTech Connect

    Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O`Connor, T.E.; Stevenson, T.N.; von Halle, A.

    1994-04-01

    Analysis of Doppler-shifted Balmer-{alpha} line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3{degrees} (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9{degrees}. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9{degrees}. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of {approximately}75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2{degrees}, rather than the 4.95{degrees} subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence.

  18. Effects of geomagnetic pulsations on the Doppler shift of HF backscatter radar echoes

    NASA Astrophysics Data System (ADS)

    Bourdillon, A.; Delloue, J.; Parent, J.

    1989-04-01

    Three mechanisms are considered for studying the effects of geomagnetic pulsations on the Doppler shifts of HF backscatter radar echoes: (1) variation of the phase refractive index under the influence of the varying magnetic component, (2) modulation of the plasma density, and (3) electrodynamic drift of the ionosphere. The electrodynamic drift is shown to be the most probable efficient mechanism to account for the measured Doppler shifts. In this model the Doppler shift on F-region propagation modes is sensitive to the eastward electric field of the wave, while E-region propagation modes are sensitive to the northward and eastward components with weights depending on the reflection height. Pi 2 and Pc 3 effects on the Doppler shift are presented, along with an example of the effects of Pi 2 pulsations on F-region and Es-region propagation modes.

  19. Coherent homodyne receiver with a compensator of Doppler shifts for inter orbit optical communication

    NASA Astrophysics Data System (ADS)

    Ando, Toshiyuki; Haraguchi, Eisuke; Tajima, Kenichi; Hirano, Yoshihito; Hanada, Tatsuyuki; Yamakawa, Shiro

    2011-03-01

    This paper presents Bread Board Model (BBM) of coherent homodyne receiver with an optical phase locked loop and a frequency compensator of Doppler shifts for inter satellite optical communication link. 2.5Gbps BPSK data has been demodulated with sensitivity of -49.1dBm at bit rate of 1e-6 under initial frequency offset of +/-7 GHz simulated as Doppler shifts due to variation of distance between each satellite.

  20. ACTIVE REGION MOSS: DOPPLER SHIFTS FROM HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS

    SciTech Connect

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2012-07-01

    Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper, we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode on 2007 December 12 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low-density cutoff as derived by Tripathi et al. in 2010. We have carried out a very careful analysis of the EIS wavelength calibration based on the method described by Young et al. in 2012. For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km s{sup -1} with an estimated error of 4-5 km s{sup -1}. The width of the distribution decreases with temperature. The mean of the distribution shows a blueshift which increases with increasing temperature and the distribution also shows asymmetries toward blueshift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. However, the fact that there are a significant number of pixels showing velocity amplitudes that exceed the uncertainty of 5 km s{sup -1} is suggestive of impulsive heating. Clearly, further observational constraints are needed to distinguish between these two heating scenarios.

  1. MEASUREMENTS OF ANISOTROPIC ION TEMPERATURES, NON-THERMAL VELOCITIES, AND DOPPLER SHIFTS IN A CORONAL HOLE

    SciTech Connect

    Hahn, M.; Savin, D. W.

    2013-02-15

    We present a new diagnostic allowing one to measure the anisotropy of ion temperatures and non-thermal velocities, as well as Doppler shifts with respect to the ambient magnetic field. This method provides new results, as well as an independent test for previous measurements obtained with other techniques. Our spectral data come from observations of a low-latitude, on-disk coronal hole. A potential field source surface model was used to calculate the angle between the magnetic field lines and the line of sight for each spatial bin of the observation. A fit was performed to determine the line widths and Doppler shifts parallel and perpendicular to the magnetic field. For each line width component we derived ion temperatures T {sub i,} and T {sub i, Parallel-To} and non-thermal velocities v {sub nt,} and v {sub nt, Parallel-To }. T {sub i,} was cooler than off-limb polar coronal hole measurements, suggesting increasing collisional cooling with decreasing height. T {sub i, Parallel-To} is consistent with a uniform temperature of (1.8 {+-} 0.2) Multiplication-Sign 10{sup 6} K for each ion. Since parallel ion heating is expected to be weak, this ion temperature should reflect the proton temperature. A comparison between our results and others implies a large proton temperature gradient around 1.02 R {sub Sun }. The non-thermal velocities are thought to be proportional to the amplitudes of various waves. Our results for v {sub nt,} agree with Alfven wave amplitudes inferred from off-limb polar coronal hole line width measurements. Our v {sub nt, Parallel-To} results are consistent with slow magnetosonic wave amplitudes inferred from Fourier analysis of time-varying intensity fluctuations. Doppler shift measurements yield outflows of Almost-Equal-To 5 km s{sup -1} for ions formed over a broad temperature range. This differs from other studies that found a strong Doppler shift dependence on formation temperature.

  2. Long-term Doppler Shift and Line Profile Studies of Planetary Search Target Stars

    NASA Technical Reports Server (NTRS)

    McMillan, Robert S.

    2002-01-01

    This grant supported attempts to develop a method for measuring the Doppler shifts of solar-type stars more accurately. The expense of future space borne telescopes to search for solar systems like our own makes it worth trying to improve the relatively inexpensive pre-flight reconnaissance by ground-based telescopes. The concepts developed under this grant contributed to the groundwork for such improvements. They were focused on how to distinguish between extrasolar planets and stellar activity (convection) cycles. To measure the Doppler shift (radial velocity; RV) of the center of mass of a star in the presence of changing convection in the star's photosphere, one can either measure the effect of convection separately from that of the star's motion and subtract its contribution to the apparent RV, or measure the RV in a way that is insensitive to convection. This grant supported investigations into both of these approaches. We explored the use of a Fabry-Perot Etalon HE interferometer and a multichannel Fourier Transform Spectrometer (mFTS), and finished making a 1.8-m telescope operational and potentially available for this work.

  3. Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials

    PubMed Central

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

    2015-01-01

    The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage. Either inverse or normal Doppler shift is realized by injecting an external RF signal into the electronically reconfigurable metamaterial, on which an electronically controllable moving reflective boundary is formed. The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit. This work is expected to open up possibilities in applying the inverse Doppler effect in wireless communications, radar and satellite navigation. PMID:26111643

  4. Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials.

    PubMed

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

    2015-01-01

    The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage. Either inverse or normal Doppler shift is realized by injecting an external RF signal into the electronically reconfigurable metamaterial, on which an electronically controllable moving reflective boundary is formed. The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit. This work is expected to open up possibilities in applying the inverse Doppler effect in wireless communications, radar and satellite navigation. PMID:26111643

  5. Constraining the orbits of small solar system bodies using spectroscopic Doppler shift measurements - a preliminary study

    NASA Astrophysics Data System (ADS)

    Zucker, S.; Tzur, I.

    2015-09-01

    In this short paper we examine whether the measurement of Doppler shifts in the solar light reflected off an asteroid surface may improve the accuracy of the determined orbit. Our results suggest it will be worthwhile to use high-resolution spectrographs, of the exoplanet-hunting type, to measure those Doppler shifts. Spectroscopic Doppler shifts might improve the accuracy of Earth-impact predictions, help to recover ``lost'' near-Earth objects, and may also significantly enhance the knowledge about dynamics of the Kuiper belt. Future high-resolution spectrographs on the VLT and the E-ELT may thus have an important role in studies of Solar-System dynamics and kinematics.

  6. Edge technique for measurement of laser frequency shifts including the Doppler shift

    NASA Technical Reports Server (NTRS)

    Korb, Larry (Inventor)

    1991-01-01

    A method is disclosed for determining the frequency shift in a laser system by transmitting an outgoing laser beam. An incoming laser beam having a frequency shift is received. A first signal is acquired by transmitting a portion of the incoming laser beam to an energy monitor detector. A second signal is acquired by transmitting a portion of the incoming laser beam through an edge filter to an edge detector, which derives a first normalized signal which is proportional to the transmission of the edge filter at the frequency of the incoming laser beam. A second normalized signal is acquired which is proportional to the transmission of the edge filter at the frequency of the outgoing laser beam. The frequency shift is determined by processing the first and second normalized signals.

  7. Observations of ULF waves on the ground and ionospheric Doppler shifts during storm sudden commencement

    NASA Astrophysics Data System (ADS)

    Ouyang, Xinyan; Liu, Wenlong; Xiao, Zuo; Hao, Yongqiang

    2016-04-01

    Using data from ground-based magnetometers and HF Doppler sounder, we study ultralow frequency (ULF) waves excited during the storm sudden commencement (SSC) on 8 March 2012 and find possible evidence on the link between ULF waves and ionospheric Doppler shifts. Pc1-Pc2 ULF waves are observed from 11:04 to 11:27 UT after the SSC by ground stations of L shell ranging from 1.06 to 2.31, mapping to the topside ionosphere. There are weak responses in this frequency range in the power spectra of ionospheric Doppler shift. From 11:19 to 11:23 UT, oscillations of magnetic field in a lower frequency range of Pc3-Pc4 are observed and are well correlated with the trace of Doppler shift. It is thus suggested that ionospheric Doppler shift can response to ULF oscillations in magnetic field in various frequency ranges, especially in the frequency range of Pc3-Pc4 and below. This paper demonstrates a new mechanism of magnetosphere-ionosphere coupling.

  8. Doppler shift and ambiguity velocity caused by relative motion in quantum-enhanced measurement.

    PubMed

    Shen, Yanghe; Xu, Luping; Zhang, Hua; Yang, Peng

    2015-07-13

    We study the effect of relative motion on a frequency-entangled-based ranging scheme. Two major puzzles arise, i.e., Doppler shift and ambiguity velocity. During condition of rapid relative motion, Doppler shift invalidates the measurement result of this scheme; while during condition of slow relative motion, the ambiguity velocity turns into a major limitation. If relative speed between targets and measurement platform exceeds the ambiguity velocity, an accumulated profile obtained by the coincidence measurement will be distorted, which causes a lower ranging accuracy. Theoretical analysis shows a time-varying delay can be introduced to solve the two major puzzles. PMID:26191903

  9. Using Doppler shift induced by Galvanometric mirror scanning to reach shot noise limit with laser optical feedback imaging setup.

    PubMed

    Jacquin, O; Lacot, E; Hugon, O; Guillet de Chatelus, H

    2015-03-10

    This paper proposes what we believe is a new method to remove the contribution of parasitic reflections in the images of the laser optical feedback imaging (LOFI) technique. This simple method allows us to extend the LOFI technique to long-distance applications, as imaging through a fog or a smoke. The LOFI technique is an ultrasensitive imaging technique that is interesting for imaging objects through a scattering medium. However, the LOFI sensitivity can be dramatically limited by parasitic optical feedback occurring in the experimental setup. In previous papers [Appl. Opt.48, 64 (2009)10.1364/AO.48.000064APOPAI1559-128X, Opt. Lett.37, 2514 (2012)10.1364/OL.37.002514OPLEDP0146-9592], we already have proposed methods to filter a parasitic optical feedback, but they are not well suited to metric working distances. This new method uses a Doppler frequency shift induced by the moving mirror used to scan the object to be imaged. Using this Doppler frequency shift, we can distinguish the photons reflected by the target and the parasitic photons reflected by the optical components in the experimental setup. In this paper, we demonstrated theoretically and experimentally the possibility to filter the parasitic reflection in LOFI images using the Doppler frequency shift. This method significantly improves the signal-to-noise ratio by a factor 15 and we can obtain a shot noise limited image through a scattering medium of an object at 3 m from the detector. PMID:25968374

  10. Can one distinguish between Doppler shifts due to source-only and detector-only velocities?

    NASA Astrophysics Data System (ADS)

    Roychoudhuri, Chandrasekhar; Ambroselli, Michael

    2013-10-01

    This paper revisits the optical Doppler shift as the classical Doppler shift based upon spectroscopic line broadening of spontaneous emission (moving source) and quantum mechanical conditions for stimulated absorption and emissions (moving detector). We find that excited emitting source-atoms and stimulated detecting-atoms clearly discern their individual absolute velocities with respect to the cosmic vacuum (Complex Tension Field, or CTF). In other words, the optical Doppler shift does not depend solely upon the relative velocity between a pair of source and detector; as the prevailing assumption is. The implication is that Doppler shifts of light coming from distant galaxies are determined by the local velocities of the emitting and detecting atoms with respect to the CTF; and the emissions frequencies remain completely independent of the velocities of the various detectors in various other galaxies; because they obey quantum mechanical transition rule Δν mn = hν mn . The released energy mn hν evolves into a wave packet of frequency mn ν only when the velocity of the source atom is zero w.r.t. CTF. Atom velocity in CTF introduces a real physical frequency shift from mn ν into med . ν . Then a detector would perceive this med . ν as det . ν due to its own velocity w.r.t CTF. The key assertion of this paper is that, the classical Doppler shift for material based waves and the optical Doppler shift for CTF based EM waves, follow the same and two different physical processes during emission and absorption and hence the representative mathematical formulation should be same as classical Doppler shift formula. Light emitted by an atom in a star in a galaxy at a distance of 10 billion years from the Sun, could not have coordinated its Doppler shift "knowing" its relative velocity with an earth based detector's; because the earth did not exist! The Sun was born barely 4 billion years ago. Calculation of optical Doppler shift based upon current relative velocity

  11. Stimulated acoustic emission: pseudo-Doppler shifts seen during the destruction of nonmoving microbubbles.

    PubMed

    Tiemann, K; Pohl, C; Schlosser, T; Goenechea, J; Bruce, M; Veltmann, C; Kuntz, S; Bangard, M; Becher, H

    2000-09-01

    The purpose of this study was to evaluate the appearance and the characteristics of stimulated acoustic emission (SAE) as an echo contrast-specific color Doppler phenomenon with impact on myocardial contrast echocardiography (MCE). Stationary microbubbles of the new contrast agent SH-U 563A (Schering AG) were embedded within a tissue-mimicking gel material. Harmonic power Doppler imaging (H-PDI), color Doppler and pulse-wave Doppler data were acquired using an HDI-5000 equipped with a phased-array transducer (1.67/3.3 MHz). In color Doppler mode, bubble destruction resulted in random noise like Doppler signals. PW-Doppler revealed short "pseudo-Doppler" shifts with a broadband frequency spectrum. Quantification of SAE events by H-PDI demonstrated an exponential decay of signal intensities over successive frames. A strong linear relationship was found between bubble concentration and the square root of the linearized H-PDI signal for a range of concentrations of more than two orders of magnitude (R = 0.993, p < 0.0001). Intensity of the H-PDI signals correlated well with emission power (R = 0.96, p = 0.0014). SAE results from disintegration of microbubbles and can be demonstrated by all Doppler imaging modalities, including H-PDI. Intensity of SAE signals is influenced by the applied acoustic power and correlates highly with the concentration of microbubbles. Because intensity of SAE signals correlates highly with echo contrast concentrations, analysis of SAE signals might be used for quantitative MCE. PMID:11053751

  12. The observation of Doppler shifts of subionospheric LF signal in possible association with earthquakes

    NASA Astrophysics Data System (ADS)

    Hayakawa, M.; Kasahara, Y.; Endoh, T.; Hobara, Y.; Asai, S.

    2012-09-01

    The Doppler-shift observation of LF (f = 60 kHz) subionospheric signal from Saga (Kyushu) (with call sign of JJY) as observed at Chofu (CHF), has been used to investigate the properties of ionospheric perturbations possibly associated with earthquakes(EQs). The period of analysis is seismo-active half a year from January 1, 2009 to June 30, 2009, and six EQs with magnitude greater than 5.0 (in a range from 5.1 to 5.8, which took place within the wave sensitive area of the JJY-CHF path) are dealt with. It is found from the Doppler-shift observation at CHF that the Doppler shifts are really observed and the components in the frequency ranges of AGW (atmospheric gravity wave) and AW (acoustic wave) in the Doppler shifts are clearly enhanced, at least, before each EQ. This observational fact would lend a strong support to the important role of atmospheric oscillation channel in the lithosphere-atmosphere-ionosphere coupling mechanism.

  13. A Doppler-Cancellation Technique for Determining the Altitude Dependence of Gravitational Red Shift in an Earth Satellite

    NASA Technical Reports Server (NTRS)

    Badessa, R. S.; Kent, R. L.; Nowell, J. C.; Searle, C. L.

    1960-01-01

    A cancellation technique permits measurement of the frequency of a source moving relative to an observer without the obscuring effect of first-order Doppler shifts. The application of this method to a gravitational red shift experiment involving the use of an earth satellite containing a highly stable oscillator is described. The rapidity with which a measurement can be made permits the taking of data at various altitudes in a given elliptical orbit. Tropospheric and ionospheric effects upon the accuracy of results are estimated.

  14. Doppler shift of hot coronal lines in a moss area of an active region

    NASA Astrophysics Data System (ADS)

    Dadashi, N.; Teriaca, L.; Tripathi, D.; Solanki, S. K.; Wiegelmann, T.

    2012-12-01

    The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the variation of Doppler shift as a function of line formation temperatures over the moss area can give clues on the heating mechanism in the hot loops in the core of the active regions. We investigate the absolute Doppler shift of lines formed at temperatures between 1 MK and 2 MK in a moss area within active region NOAA 11243 using a novel technique that allows determining the absolute Doppler shift of EUV lines by combining observations from the SUMER and EIS spectrometers. The inner (brighter and denser) part of the moss area shows roughly constant blue shift (upward motions) of 5 km s-1 in the temperature range of 1 MK to 1.6 MK. For hotter lines the blue shift decreases and reaches 1 km s-1 for Fe xv 284 Å (~2 MK). The measurements are discussed in relation to models of the heating of hot loops. The results for the hot coronal lines seem to support the quasi-steady heating models for nonsymmetric hot loops in the core of active regions.

  15. Method for ambiguity resolution in range-Doppler measurements

    NASA Technical Reports Server (NTRS)

    Heymsfield, Gerald M. (Inventor); Miller, Lee S. (Inventor)

    1994-01-01

    A method for resolving range and Doppler target ambiguities when the target has substantial range or has a high relative velocity in which a first signal is generated and a second signal is also generated which is coherent with the first signal but at a slightly different frequency such that there exists a difference in frequency between these two signals of Delta f(sub t). The first and second signals are converted into a dual-frequency pulsed signal, amplified, and the dual-frequency pulsed signal is transmitted towards a target. A reflected dual-frequency signal is received from the target, amplified, and changed to an intermediate dual-frequency signal. The intermediate dual-frequency signal is amplified, with extracting of a shifted difference frequency Delta f(sub r) from the amplified intermediate dual-frequency signal done by a nonlinear detector. The final step is generating two quadrature signals from the difference frequency Delta f(sub t) and the shifted difference frequency Delta f(sub r) and processing the two quadrature signals to determine range and Doppler information of the target.

  16. Fracture toughness curve shift method

    SciTech Connect

    Nanstad, R.K.; Sokolov, M.A.; McCabe, D.E.

    1995-10-01

    The purpose of this task is to examine the technical basis for the currently accepted methods for shifting fracture toughness curves to account for irradiation damage, and to work through national codes and standards bodies to revise those methods, if a change is warranted. During this reporting period, data from all the relevant HSSI Programs were acquired and stored in a database and evaluated. The results from that evaluation have been prepared in a draft letter report and are summarized here. A method employing Weibull statistics was applied to analyze fracture toughness properties of unirradiated and irradiated pressure vessel steels. Application of the concept of a master curve for irradiated materials was examined and used to measure shifts of fracture toughness transition curves. It was shown that the maximum likelihood approach gave good estimations of the reference temperature, T{sub o}, determined by rank method and could be used for analyzing of data sets where application of the rank method did not prove to be feasible. It was shown that, on average, the fracture toughness shifts generally exceeded the Charpy 41-J shifts; a linear least-squares fit to the data set yielded a slope of 1.15. The observed dissimilarity was analyzed by taking into account differences in effects of irradiation on Charpy impact and fracture toughness properties. Based on these comparisons, a procedure to adjust Charpy 41-J shifts for achieving a more reliable correlation with the fracture toughness shifts was evaluated. An adjustment consists of multiplying the 41-J energy level by the ratio of unirradiated to irradiated Charpy upper shelves to determine an irradiated transition temperature, and then subtracting the unirradiated transition temperature determined at 41 J. For LUS welds, however, an unirradiated level of 20 J (15 ft-1b) was used for the corresponding adjustment for irradiated material.

  17. Linear ion trap for second-order Doppler shift reduction in frequency standard applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Janik, Gary R.; Dick, G. John; Maleki, Lute

    1990-01-01

    The authors have designed and are presently testing a novel linear ion trap that permits storage of a large number of ions with reduced susceptibility to the second-order Doppler effect caused by the RF confining fields. This new trap should store about 20 times the number of ions as a conventional RF trap with no corresponding increase in second-order Doppler shift from the confining field. In addition, the sensitivity of this shift to trapping parameters, i.e., RF voltage, RF frequency, and trap size, is greatly reduced. The authors have succeeded in trapping mercury ions and xenon ions in the presence of helium buffer gas. Trap times as long as 2000 s have been measured.

  18. Development of the One-Sided Nonlinear Adaptive Doppler Shift Estimation

    NASA Technical Reports Server (NTRS)

    Beyon, Jeffrey Y.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.; Serror, Judith A.

    2009-01-01

    The new development of a one-sided nonlinear adaptive shift estimation technique (NADSET) is introduced. The background of the algorithm and a brief overview of NADSET are presented. The new technique is applied to the wind parameter estimates from a 2-micron wavelength coherent Doppler lidar system called VALIDAR located in NASA Langley Research Center in Virginia. The new technique enhances wind parameters such as Doppler shift and power estimates in low Signal-To-Noise-Ratio (SNR) regimes using the estimates in high SNR regimes as the algorithm scans the range bins from low to high altitude. The original NADSET utilizes the statistics in both the lower and the higher range bins to refine the wind parameter estimates in between. The results of the two different approaches of NADSET are compared.

  19. Measuring D(d,p)T fusion reactant energy spectra with Doppler shifted fusion products

    SciTech Connect

    Boris, D. R.; Kulcinski, G. L.; Santarius, J. F.; Donovan, D. C.; Piefer, G. R.

    2010-06-15

    Deuterium fusion reactant energy spectra have been measured using a diagnostic that records the Doppler shift imparted to charged particle fusion products of the D(d,p)T reaction by the center-of-mass velocity of the deuterium reactants. This diagnostic, known as the fusion ion Doppler shift diagnostic (FIDO) measures fast deuterium energy spectra in the inertial electrostatic confinement (IEC) experiment at the University of Wisconsin-Madison {l_brace}Santarius et al. [Fusion Sci. Technol. 47, 1238 (2005)]{r_brace}, a device to confine high energy light ions in a spherically symmetric, electrostatic potential well. This article details the first measurements of the fusion reactant energy spectra in an IEC device as well as the design and principles of operation of the FIDO diagnostic. Scaling of reactant energy spectra with a variety of experimental parameters have been explored.

  20. Quasi-periodic variations in the Doppler shift of HF signals scattered by artificial ionospheric turbulence

    SciTech Connect

    Belenov, A.F.; Ponomarenko, P.V.; Sinitsyn, V.G.; Yampol`skii, Yu.M.

    1994-06-01

    The results of an experimental study of quasi-periodic variations of the Doppler shift (DS) of decimeter-wave signals scattered by artificial ionospheric turbulence are presented. It is suggested that ionospheric MHD waves of natural origin are a possible cause of such variations. The amplitude of the magnetic component of such waves that leads to observable values of DS variations is estimated to be 1{gamma}.

  1. Quasi-periodic variations in the Doppler shift of HF signals scattered by artificial ionospheric turbulence

    NASA Astrophysics Data System (ADS)

    Belenov, A. F.; Ponomarenko, P. V.; Sinitsyn, V. G.; Yampol'Skii, Yu. M.

    1993-12-01

    The results of an experimental study of quasi-periodic variations of the Doppler shift (DS) of decimeter-wave signals scattered by artificial ionospheric turbulence are presented. It is suggested that ionospheric MHD waves of natural origin are a possible cause of such variations. The amplitude of the magnetic component of such waves that leads to observable values of DS variations is estimated to be 1γ.

  2. The gust-front detection and wind-shift algorithms for the Terminal Doppler Weather Radar system

    NASA Technical Reports Server (NTRS)

    Hermes, Laurie G.; Witt, Arthur; Smith, Steven D.; Klingle-Wilson, Diana; Morris, Dale; Stumpf, Gregory J.; Eilts, Michael D.

    1993-01-01

    The Federal Aviation Administration's (FAA) Terminal Doppler Weather Radar (TDWR) system was primarily designed to address the operational needs of pilots in the avoidance of low-altitude wind shears upon takeoff and landing at airports. One of the primary methods of wind-shear detection for the TDWR system is the gust-front detection algorithm. The algorithm is designed to detect gust fronts that produce a wind-shear hazard and/or sustained wind shifts. It serves the hazard warning function by providing an estimate of the wind-speed gain for aircraft penetrating the gust front. The gust-front detection and wind-shift algorithms together serve a planning function by providing forecasted gust-front locations and estimates of the horizontal wind vector behind the front, respectively. This information is used by air traffic managers to determine arrival and departure runway configurations and aircraft movements to minimize the impact of wind shifts on airport capacity. This paper describes the gust-front detection and wind-shift algorithms to be fielded in the initial TDWR systems. Results of a quantitative performance evaluation using Doppler radar data collected during TDWR operational demonstrations at the Denver, Kansas City, and Orlando airports are presented. The algorithms were found to be operationally useful by the FAA airport controllers and supervisors.

  3. Sensitivity Correction Control of the Ultrasonic Sensor due to Doppler Shift

    NASA Astrophysics Data System (ADS)

    Koike, Yoshikazu; Aizawa, Shin-ichi

    2008-05-01

    Authors propose the use of an ultrasonic transducer to achieve a passive safety system for a collision using a corner sensor. However, the sensitivity of the transducer decreases owing to Doppler shift in the case of a travelling car. On the contrary, authors also propose a resonance control method for the transducer using a generalized impedance converter (GIC) circuit. In this study, the resonance control frequency method is used to correct the sensitivity of the transducer. In the sensitivity control, the input impedance control of the GIC circuit is tried using a voltage-controlled resistance. The automatic sensitivity correction control is expected to be realized by a combination of the GIC circuit and frequency-voltage (F/V) converter. As a result, the sensitivity of a Langevin transducer with a GIC circuit as a receiver is slightly improved, compared with that of a retailed transducer. Moreover, the resonance frequency of the transducer can be controlled in the range of about 3 kHz using the GIC circuit and F/V converter.

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

    NASA Astrophysics Data System (ADS)

    Borisova, T. D.; Blagoveshchenskaya, N. F.; Moskvin, I. V.; Rietveld, M. T.; Kosch, M. J.; Thidé, B.

    2002-09-01

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

  5. CONSTRAINING HIGH-SPEED WINDS IN EXOPLANET ATMOSPHERES THROUGH OBSERVATIONS OF ANOMALOUS DOPPLER SHIFTS DURING TRANSIT

    SciTech Connect

    Miller-Ricci Kempton, Eliza; Rauscher, Emily

    2012-06-01

    Three-dimensional (3D) dynamical models of hot Jupiter atmospheres predict very strong wind speeds. For tidally locked hot Jupiters, winds at high altitude in the planet's atmosphere advect heat from the day side to the cooler night side of the planet. Net wind speeds on the order of 1-10 km s{sup -1} directed towards the night side of the planet are predicted at mbar pressures, which is the approximate pressure level probed by transmission spectroscopy. These winds should result in an observed blueshift of spectral lines in transmission on the order of the wind speed. Indeed, Snellen et al. recently observed a 2 {+-} 1 km s{sup -1} blueshift of CO transmission features for HD 209458b, which has been interpreted as a detection of the day-to-night (substellar to anti-stellar) winds that have been predicted by 3D atmospheric dynamics modeling. Here, we present the results of a coupled 3D atmospheric dynamics and transmission spectrum model, which predicts the Doppler-shifted spectrum of a hot Jupiter during transit resulting from winds in the planet's atmosphere. We explore four different models for the hot Jupiter atmosphere using different prescriptions for atmospheric drag via interaction with planetary magnetic fields. We find that models with no magnetic drag produce net Doppler blueshifts in the transmission spectrum of {approx}2 km s{sup -1} and that lower Doppler shifts of {approx}1 km s{sup -1} are found for the higher drag cases, results consistent with-but not yet strongly constrained by-the Snellen et al. measurement. We additionally explore the possibility of recovering the average terminator wind speed as a function of altitude by measuring Doppler shifts of individual spectral lines and spatially resolving wind speeds across the leading and trailing terminators during ingress and egress.

  6. Doppler-shifting effects on frequency spectra of gravity waves observed near the summer mesopause at high latitude

    NASA Technical Reports Server (NTRS)

    Fritts, David C.; Wang, Ding-Yi

    1991-01-01

    Results are presented of radar observations of horizontal and vertical velocities near the summer mesopause at Poker Flat (Alaska), showing that the observed vertical velocity spectra were influenced strongly by Doppler-shifting effects. The horizontal velocity spectra, however, were relatively insensitive to horizontal wind speed. The observed spectra are compared with predicted spectra for various models of the intrinsic motion spectrum and degrees of Doppler shifting.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  8. Doppler-shift estimation of flat underwater channel using data-aided least-square approach

    NASA Astrophysics Data System (ADS)

    Pan, Weiqiang; Liu, Ping; Chen, Fangjiong; Ji, Fei; Feng, Jing

    2015-06-01

    In this paper we proposed a dada-aided Doppler estimation method for underwater acoustic communication. The training sequence is non-dedicate, hence it can be designed for Doppler estimation as well as channel equalization. We assume the channel has been equalized and consider only flat-fading channel. First, based on the training symbols the theoretical received sequence is composed. Next the least square principle is applied to build the objective function, which minimizes the error between the composed and the actual received signal. Then an iterative approach is applied to solve the least square problem. The proposed approach involves an outer loop and inner loop, which resolve the channel gain and Doppler coefficient, respectively. The theoretical performance bound, i.e. the Cramer-Rao Lower Bound (CRLB) of estimation is also derived. Computer simulations results show that the proposed algorithm achieves the CRLB in medium to high SNR cases.

  9. Doppler-shift compensation behavior by Wagner’s mustached bat, Pteronotus personatus

    PubMed Central

    Smotherman, Michael; Guillén-Servent, Antonio

    2008-01-01

    Doppler-shift compensation behavior (DSC) is a highly specialized vocal response displayed by bats that emit pulses with a prominent constant frequency (CF) component and adjust the frequency of their CF component to compensate for flight-speed induced Doppler shifts in the frequency of the returning echoes. DSC has only been observed in one member of the Neotropical Mormoopidae, a family of bats that use pulses with prominent CF components, leading researchers to suspect that DSC is a uniquely derived trait in the single species Pteronotus parnellii. Yet recent phylogenetic data indicate that the lineage of P. parnellii originates from the most basal node in the evolutionary history of the genus Pteronotus. DSC behavior was investigated in another member of this family, Pteronotus personatus, because molecular data indicated that this species stems from the second most basal node in Pteronotus. DSC was tested for by swinging the bats on a pendulum. P. personatus performed DSC as well as P. parnellii under identical conditions. Two other closely related mormoopids, Pteronotus davyi and Mormoops megalophylla, were also tested and neither shifted the peak frequency of their pulses. These results shed light on the evolutionary history of DSC among the mormoopids. PMID:18537384

  10. Optical Filters to Exclude Non-Doppler-Shifted Light in Fast Velocimetry

    SciTech Connect

    Goosman, D; Avara, G; Wade, J; Rivera, A

    2002-08-22

    We frequently measure velocity-time histories of dynamic experiments. In some, the Doppler-shifted light is often weak compared to non-shifted light reflected from stationary surfaces and imperfections in components. With our Fabry-Perot (FP) based systems which handle multiple frequencies, data is lost where the fringes coincide; if we had used an intensity-measuring VISAR system, it would probably fail. We designed a facility for doing experiments under such conditions by selectively eliminating most of the non-shifted light. Our first filter excluded non-shifted light by a factor of 300 when manually tuned, and by 150 when run in an auto-tuning mode. It used a single 50 mm diameter FP as the filter with a spacing of 1.65 mm and reflectivities of 77%, and filters five channels prior to use in one of our 5-beam velocimeters. One use of the filter system was to embed optical fibers in long sections of explosives to make continuous detonation velocity-time histories. We have carried out many such tests with this filter, and two without. A special single-beam filter was constructed with a 40% efficiency for shifted light that rejected non-shifted light by 4 million times, with a bandpass of a few GHz.

  11. New lifetime measurements in the stable semimagic Sn isotopes using the Doppler-shift attenuation technique

    NASA Astrophysics Data System (ADS)

    Jungclaus, A.; Walker, J.; Leske, J.; Speidel, K.-H.; Stuchbery, A. E.; East, M.; Boutachkov, P.; Cederkäll, J.; Doornenbal, P.; Egido, J. L.; Ekström, A.; Gerl, J.; Gernhäuser, R.; Goel, N.; Górska, M.; Kojouharov, I.; Maier-Komor, P.; Modamio, V.; Naqvi, F.; Pietralla, N.; Pietri, S.; Prokopowicz, W.; Schaffner, H.; Schwengner, R.; Wollersheim, H.-J.

    2011-09-01

    Precise measurements of lifetimes in the picosecond range of excited states in the stable even-A Sn isotopes 112,114,116,122Sn have been performed using the Doppler shift attenuation technique. For the first excited 2+ states in 112Sn, 114Sn and 116Sn the E2 transition strengths deduced from the measured lifetimes are in disagreement with the previously adopted values. They indicate a shallow minimum at N = 66 in contrast to the maximum at mid-shell predicted by modern shell model calculations.

  12. A digital multigate Doppler method for high frequency ultrasound.

    PubMed

    Qiu, Weibao; Ye, Zongying; Yu, Yanyan; Chen, Yan; Chi, Liyang; Mu, Peitian; Li, Guofeng; Wang, Congzhi; Xiao, Yang; Dai, Jiyan; Sun, Lei; Zheng, Hairong

    2014-01-01

    Noninvasive visualization of blood flow with high frequency Doppler ultrasound has been extensively used to assess the morphology and hemodynamics of the microcirculation. A completely digital implementation of multigate pulsed-wave (PW) Doppler method was proposed in this paper for high frequency ultrasound applications. Analog mixer was eliminated by a digital demodulator and the same data acquisition path was shared with traditional B-mode imaging which made the design compact and flexible. Hilbert transform based quadrature demodulation scheme was employed to achieve the multigate Doppler acquisition. A programmable high frequency ultrasound platform was also proposed to facilitate the multigate flow visualization. Experimental results showed good performance of the proposed method. Parabolic velocity gradient inside the vessel and velocity profile with different time slots were acquired to demonstrate the functionality of the multigate Doppler. Slow wall motion was also recorded by the proposed method. PMID:25061836

  13. A Digital Multigate Doppler Method for High Frequency Ultrasound

    PubMed Central

    Qiu, Weibao; Ye, Zongying; Yu, Yanyan; Chen, Yan; Chi, Liyang; Mu, Peitian; Li, Guofeng; Wang, Congzhi; Xiao, Yang; Dai, Jiyan; Sun, Lei; Zheng, Hairong

    2014-01-01

    Noninvasive visualization of blood flow with high frequency Doppler ultrasound has been extensively used to assess the morphology and hemodynamics of the microcirculation. A completely digital implementation of multigate pulsed-wave (PW) Doppler method was proposed in this paper for high frequency ultrasound applications. Analog mixer was eliminated by a digital demodulator and the same data acquisition path was shared with traditional B-mode imaging which made the design compact and flexible. Hilbert transform based quadrature demodulation scheme was employed to achieve the multigate Doppler acquisition. A programmable high frequency ultrasound platform was also proposed to facilitate the multigate flow visualization. Experimental results showed good performance of the proposed method. Parabolic velocity gradient inside the vessel and velocity profile with different time slots were acquired to demonstrate the functionality of the multigate Doppler. Slow wall motion was also recorded by the proposed method. PMID:25061836

  14. Kündig's experiment on the transverse Doppler shift re-analyzed

    NASA Astrophysics Data System (ADS)

    Kholmetskii, A. L.; Yarman, T.; Missevitch, O. V.

    2008-03-01

    In this paper, we re-analyze the ingenious experiment by Kündig (measurement of the transverse Doppler shift by means of the Mössbauer effect) and show that a correct processing of experimental data gives a relative energy shift ΔE/E of the absorption line different from the value of classically assumed relativistic time dilation for a rotating resonant absorber. Namely, instead of the relative energy shift {{\\Delta E} / {E = - (1.0065 \\pm 0.011){{v^2 } / {2c^2 }}}} reported by Kündig (v being the linear velocity of absorber and c being the light velocity in vacuum), we derive from his results {{\\Delta E} / {E = - (1.192 \\pm 0.011){{v^2 } / {2c^2 }}}}. We are inclined to think that the revealed deviation of ΔE/E from relativistic prediction cannot be explained by any instrumental error and thus represents a physical effect. In particular, we assume that the energy shift of the absorption resonant line is induced not only by the standard time dilation effect, but also by some additional effect missed at the moment, and related perhaps to the fact that resonant nuclei in the rotating absorber represent a macroscopic quantum system and cannot be considered as freely moving particles.

  15. Search for Doppler-shifted gamma-ray emission from SS 433 using the SMM spectrometer

    NASA Technical Reports Server (NTRS)

    Geldzahler, B. J.; Share, G. H.; Kinzer, R. L.; Magura, J.; Chupp, E. L.

    1989-01-01

    Data accumulated from 1980 to 1983 with the Gamma Ray Spectrometer aboard NASA's Solar Maximum Mission (SMM) satellite were searched for evidence of red and blue Doppler-shifted 1.37 MeV Mg-24 nuclear lines from SS 433. The SMM data base covers 270 days when SS 433 was in the field of view and includes periods of radio flaring and quiescence. No evidence was found for Doppler-shifted line emission in any of the spectra. The range of 3-sigma upper limits for individual 9 day integration periods was 0.0008-0.0023 photons/sq cm per sec for the blue beam, encompassing the reported about 1.5 MeV line, and 0.0008-0.002 photons/sq cm per sec for the red beam, encompassing the reported about 1.2 MeV line; the average 3-sigma upper limit in each beam for shifted about 1.37 MeV lines is 0.0015 photons/sq cm per sec for single 9 day integrations. The 3-sigma upper limit on 1.37 MeV gamma-ray emission over 23 9-day integration intervals for the red beam and 28 intervals for the blue beam is 0.0002 photons/sq cm per sec. These new limits from SMM can be reconciled with the HEAO 3 results only if SS 433 emits gamma radiation at or above the SMM sensitivity limit on rare occasions due to variable physical conditions in the system.

  16. Laser Doppler spectrometer method of particle sizing. [for air pollution

    NASA Technical Reports Server (NTRS)

    Weber, F. N.

    1976-01-01

    A spectrometer for the detection of airborne particulate pollution in the submicron size range is described. In this device, airborne particles are accelerated through a supersonic nozzle, with different sizes achieving different velocities in the gas flow. Information about the velocities of the accelerated particles is obtained with a laser-heterodyne optical system through the Doppler shift of light scattered from the particles. Detection is accomplished by means of a photomultiplier. Nozzle design and signal processing techniques are also discussed.

  17. A beamforming method for plane wave Doppler imaging of high flow velocities

    NASA Astrophysics Data System (ADS)

    Mansour, Omar; Poepping, Tamie L.; Lacefield, James C.

    2016-04-01

    Plane wave imaging is desirable for its ability to achieve high frame rates, allowing the capture of fast dynamic events, and continuous Doppler data. In most implementations of plane-wave imaging, multiple low resolution image (LRI) frames from different plane wave tilt angles are compounded to form a single high resolution image (HRI) frame, thereby reducing the frame rate. Compounding is a low-pass mean filter that causes attenuation and aliasing to signals with high Doppler shifts. On the other hand, the lateral beam profile and hence the quality of the HRI frames is improved by increasing the number of compounded frames. Therefore, a tradeoff exists between the Doppler limits and beam profile. In this paper, we present a method that eliminates this tradeoff and produces high resolution images without the use of compounding. The method suppresses the off-focus (clutter) signal by spreading its spectrum, while keeping the spectrum of the in-focus signal intact. The spreading is achieved by using a random sequence of tilt angles, as opposed to a linear sweep. Experiments performed using a carotid vessel phantom with constant flow demonstrate that the spread-spectrum method more accurately measures the parabolic flow profile of the vessel and in particular outperforms conventional plane-wave Doppler at higher flow velocities. The spread-spectrum method is expected to be valuable for Doppler applications that require measurement of high velocities at high frame rates.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  19. Doppler shift estimation for GNSS reflectometry using a land topography adapted reflection model

    NASA Astrophysics Data System (ADS)

    Semmling, Maximilian; Peraza, Luis; Falck, Carsten; Gerland, Sebastian; Wickert, Jens

    2016-04-01

    A GNSS setup with a receiver capable for reflectometry is operated by GFZ at Kongsfjorden (Spitsbergen), 78°54'14''N, 11°52'37''E, 512 m above ellipsoid (WGS-84). This permanent station at the Zeppelin mountain outpost, operated by the Norwegian Polar Institute (NPI), accumulates data since Summer 2013 observing reflections over the fjord and the adjacent land surface. Especially the presence of sea ice over the fjord and snow cover over land are of interest for reflectometry to investigate altimetry and remote sensing applications. The setup contains a GORS (GNSS Occultation Reflectometry Scatterometry) two-frontend receiver, which is based on commercial JAVAD hardware. The receiver is connected to one up-looking and one horizon-looking patch antenna with right-handed and left-handed circular polarization, respectively. Both antennas are installed on the same mount approximately 475 m above the fjord mean sea level. Reflections are observed at low transmitter elevation angles (between 10 and 2°). For these geometries the relative Doppler shift (sea surface reflected relative to direct signal) is almost constant 0.5 to 0.6 Hz and can be calculated with an established reflection model. Rather easily, sea surface reflections are identified in the data and the corresponding reflection points are located. About 55 daily recurring reflection events over the fjord are observed. They form a fan-shaped swath with 3 to 13 km distance around the receiver, corresponding to elevations of 10° to 2°. Also signatures of potential land reflections are found in the data. About 13 daily recurring events extend mainly over land. The potential land signatures have a rather variable Doppler shift between 0.2 to 1Hz. The significant topography of the mountainous surrounding, which varies between sea level and 900 m altitude, prevents the use of established reflection models. A topography adapted reflection model, which considers sloped surface facets, is developed. It incorporates

  20. Measurement of the rotational Doppler frequency shift of a spinning object using a radio frequency orbital angular momentum beam.

    PubMed

    Zhao, Mingyang; Gao, Xinlu; Xie, Mutong; Zhai, Wensheng; Xu, Wenjing; Huang, Shanguo; Gu, Wanyi

    2016-06-01

    An indirect approach based on phase measurement is proposed to measure the rotational Doppler frequency shift, which takes full advantage of the phase structure of orbital angular momentum (OAM) beams in radio domain, using a vector network analyzer (VNA) as a phase discriminator. A proof-of-concept experiment is established by an optical-controlled system with the OAM state of 1. By analyzing the experiment's results, the rotational Doppler frequency shift is measured as 24.83 Hz (max error rate 0.67%) at 50π rad/s rotational velocity, deducing the rotational velocity as 50.18π (average error rate 0.36%). PMID:27244411

  1. Red Shift, Blue Shift: Investigating Doppler Shifts, Blubber Thickness, and Migration as Explanations of Seasonal Variation in the Tonality of Antarctic Blue Whale Song

    PubMed Central

    Miller, Brian S.; Leaper, Russell; Calderan, Susannah; Gedamke, Jason

    2014-01-01

    The song of Antarctic blue whales (Balaenoptera musculus intermedia) comprises repeated, stereotyped, low-frequency calls. Measurements of these calls from recordings spanning many years have revealed a long-term linear decline as well as an intra-annual pattern in tonal frequency. While a number of hypotheses for this long-term decline have been investigated, including changes in population structure, changes in the physical environment, and changes in the behaviour of the whales, there have been relatively few attempts to explain the intra-annual pattern. An additional hypothesis that has not yet been investigated is that differences in the observed frequency from each call are due to the Doppler effect. The assumptions and implications of the Doppler effect on whale song are investigated using 1) vessel-based acoustic recordings of Antarctic blue whales with simultaneous observation of whale movement and 2) long-term acoustic recordings from both the subtropics and Antarctic. Results from vessel-based recordings of Antarctic blue whales indicate that variation in peak-frequency between calls produced by an individual whale was greater than would be expected by the movement of the whale alone. Furthermore, analysis of intra-annual frequency shift at Antarctic recording stations indicates that the Doppler effect is unlikely to fully explain the observations of intra-annual pattern in the frequency of Antarctic blue whale song. However, data do show cyclical changes in frequency in conjunction with season, thus suggesting that there might be a relationship among tonal frequency, body condition, and migration to and from Antarctic feeding grounds. PMID:25229644

  2. Red shift, blue shift: investigating Doppler shifts, blubber thickness, and migration as explanations of seasonal variation in the tonality of Antarctic blue whale song.

    PubMed

    Miller, Brian S; Leaper, Russell; Calderan, Susannah; Gedamke, Jason

    2014-01-01

    The song of Antarctic blue whales (Balaenoptera musculus intermedia) comprises repeated, stereotyped, low-frequency calls. Measurements of these calls from recordings spanning many years have revealed a long-term linear decline as well as an intra-annual pattern in tonal frequency. While a number of hypotheses for this long-term decline have been investigated, including changes in population structure, changes in the physical environment, and changes in the behaviour of the whales, there have been relatively few attempts to explain the intra-annual pattern. An additional hypothesis that has not yet been investigated is that differences in the observed frequency from each call are due to the Doppler effect. The assumptions and implications of the Doppler effect on whale song are investigated using 1) vessel-based acoustic recordings of Antarctic blue whales with simultaneous observation of whale movement and 2) long-term acoustic recordings from both the subtropics and Antarctic. Results from vessel-based recordings of Antarctic blue whales indicate that variation in peak-frequency between calls produced by an individual whale was greater than would be expected by the movement of the whale alone. Furthermore, analysis of intra-annual frequency shift at Antarctic recording stations indicates that the Doppler effect is unlikely to fully explain the observations of intra-annual pattern in the frequency of Antarctic blue whale song. However, data do show cyclical changes in frequency in conjunction with season, thus suggesting that there might be a relationship among tonal frequency, body condition, and migration to and from Antarctic feeding grounds. PMID:25229644

  3. Local time distribution of the SSC-associated HF-Doppler frequency shifts

    NASA Technical Reports Server (NTRS)

    Kikuchi, T.; Sugiuchi, H.; Ishimine, T.

    1985-01-01

    The HF-Doppler frequency shift observed at the storm's sudden commencement is composed of a frequency increase (+) and decrease (-), and classified into four types, SCF(+ -), SCF(- +), SCF(+) and SCF(-). Since the latter two types are special cases of the former two types, two different kinds of electrical field exist in the F region and cause the ExB drift motion of plasma. HUANG (1976) interpreted the frequency increase of SCF(+ -) as due to the westward induction electric field proportional to delta H/ delta t and the succeeding frequency decrease due to the eastward conduction electric field which produces ionospheric currents responsible for the magnetic increase on the ground. In spite of his success in interpreting the SCF(+ -), some other interpretations are needed for the explanation of the whole set of SCF's, particularly SCF(- +). Local time distributions of the SCF's are derived from 41 SCF's which are observed on the HF standard signal (JJY) as received in Okinawa (path length =1600 km) and Kokubunji (60 km). It is shown that the SCF(+ -) appears mainly during the day, whereas the SCF(- +) is observed during the night. The results indicate that the preliminary frequency shift (+) of SCF(+ -) and (-) of SCF(- +) is caused by a westward electric field in the dayside hemisphere, while by an eastward electric field in the nightside hemisphere. The main frequency shift (-) of SCF(+ -) and (+) of SCF(- +) is caused by the reversed electric field. Consequently, the preliminary frequency shift is caused by the dusk-to-dawn electric field, while the main frequency shift by the dawn-to-dusk electric field.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  5. Effect of Doppler-shifted photons on subnanosecond breakdown in high-voltage pulse discharge

    NASA Astrophysics Data System (ADS)

    Schweigert, I. V.; Alexandrov, A. L.; Zakrevsky, Dm. E.; Bokhan, P. A.

    2016-06-01

    The experiments in high-voltage open discharge in helium [1, 2] showed a controlled current growth rate of 500 A/(cm2ns) for an applied voltage of 20 kV and gas pressure of 6 Torr. A kinetic model of the subnanosecond breakdown is developed to analyze the mechanism of current growth, which takes into account the kinetics of electrons, ions, fast atoms and photons with a Doppler shift (DS). DS photons appear in discharge due to collisions of heavy particles. Using particle in cell simulations, we show a critical role of DS photons in the electron emission from the cathode during the breakdown. Our experimental and calculation results show a decrease of the breakdown time with increasing gas pressure from 3 Torr to 16 Torr.

  6. A technique for calculating ionospheric Doppler shifts from standard ionograms suitable for scientific, HF communication, and OTH radar applications

    NASA Astrophysics Data System (ADS)

    Lynn, K. J. W.

    2009-12-01

    High-resolution Doppler ionograms taken at 5 min intervals were obtained from a KEL IPS 71 ionosonde operating over a full ionosonde sweep range. The ionograms were converted into true height profiles using the program POLAN. POLAN also produced an equivalent parabolic layer model of best fit to the true height profile. A parabolic layer model of the ionosphere is defined by three parameters, namely, peak height, maximum electron density/critical frequency, and parabolic thickness. Equations for calculating Doppler shift from a time-varying parabolic layer model have long been known but have seen remarkably little use in the absence of suitable input data and a means of verifying the results. This paper shows that these equations can provide an accurate means of calculating ionospheric Doppler shift based on standard ionospheric ionograms taken at a 5 min rate over a 24 h period when compared with actual Doppler measurements. Apart from its scientific interest, the demonstrated technique will prove particularly valuable in deriving Doppler shift and associated signal fading for the real-time control of over-the-horizon radar and HF communication links.

  7. A Human Gait Classification Method Based on Radar Doppler Spectrograms

    NASA Astrophysics Data System (ADS)

    Tivive, Fok Hing Chi; Bouzerdoum, Abdesselam; Amin, Moeness G.

    2010-12-01

    An image classification technique, which has recently been introduced for visual pattern recognition, is successfully applied for human gait classification based on radar Doppler signatures depicted in the time-frequency domain. The proposed method has three processing stages. The first two stages are designed to extract Doppler features that can effectively characterize human motion based on the nature of arm swings, and the third stage performs classification. Three types of arm motion are considered: free-arm swings, one-arm confined swings, and no-arm swings. The last two arm motions can be indicative of a human carrying objects or a person in stressed situations. The paper discusses the different steps of the proposed method for extracting distinctive Doppler features and demonstrates their contributions to the final and desirable classification rates.

  8. Photoacoustic Doppler flowmetry of carbon particles flow using an autocorrelation method

    NASA Astrophysics Data System (ADS)

    Lu, Tao

    2014-11-01

    In order to measure the axial flowing velocity of carbon particle suspension with particle diameter of tens of micrometers, the photoacoustic Doppler (PAD) frequency shift is calculated based on a series of individual A scans using an autocorrelation method. A 532 nm pulsed laser with repetition rate of 20 Hz is used as a pumping source to generate photoacoustic signal. The photoacoustic signals are detected using a focused piezoelectric (PZT) ultrasound transducer with central frequency of 5 MHz. The suspension of carbon particles is driven by a syringe pump. The complex photoacoustic signal is calculated by the Hilbert transformation from time-domain photoacoustic signal, and then it is autocorrelated to calculate the Doppler frequency shift. The photoacoustic Doppler frequency shift is calculated by averaging the autocorrelation results of some individual A scans. The advantage of the autocorrelation method is that the time delay in autocorrelation can be defined by user, and the requirement of high pulse repetition rate is avoided. The feasibility of the proposed autocorrelation method is preliminarily demonstrated by quantifying the motion of a carbon particle suspension with flow velocity from 5 mm/s to 60 mm/s. The experimental results show that there is an approximately linear relation between the autocorrelation result and the setting velocity.

  9. Non-Doppler shift related experimental shock wave measurements using velocity interferometer systems for any reflector

    SciTech Connect

    Forsman, A. C.; Kyrala, G. A.

    2001-05-01

    Velocity interferometer system for any reflectors (VISARs), are becoming increasingly popular in the measurement of shock waves in solids and liquids. VISAR techniques are used in measurements of transit time, speed of shock waves in flight in transparent media [L. C. Chhabildas and J. L. Wise, in Proceedings of the 4th APS Topical Conference on Shock Waves in Condensed Matter, Spokane, Washington, 1985, edited by Y. M. Gupta (Plenum, New York, 1986); P. M. Celliers , Appl. Phys. Lett. 73, 1320 (1998)], and in measurements of particle velocity. However, in cases where shock compression or release may change the index of refraction n+ik of the material being studied, the VISAR technique must be applied with care. Changes in n and k introduce phase shifts into the VISAR results that are not associated with changes in velocity. This paper presents a derivation of the theoretical output of a line VISAR that includes the effects of changing n and k and an experimental observation of a non-Doppler shift related effect.

  10. Measurement of Ultracold Neutrons Produced by Using Doppler-shifted Bragg Reflection at a Pulsed-neutron Source

    DOE R&D Accomplishments Database

    Brun, T. O.; Carpenter, J. M.; Krohn, V. E.; Ringo, G. R.; Cronin, J. W.; Dombeck, T. W.; Lynn, J. W.; Werner, S. A.

    1979-01-01

    Ultracold neutrons (UCN) have been produced at the Argonne pulsed-neutron source by the Doppler shift of 400-m/s neutrons Bragg reflected from a moving crystal. The peak density of UCN produced at the crystal exceeds 0.1 n/cm{sup 3}.

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  12. Harmonic Motion Microwave Doppler Imaging method for breast tumor detection.

    PubMed

    Top, Can Barıs; Tafreshi, Azadeh Kamali; Gençer, Nevzat G

    2014-01-01

    Harmonic Motion Microwave Doppler Imaging (HMMDI) method is recently proposed as a non-invasive hybrid breast imaging technique for tumor detection. The acquired data depend on acoustic, elastic and electromagnetic properties of the tissue. The potential of the method is analyzed with simulation studies and phantom experiments. In this paper, the results of these studies are summarized. It is shown that HMMDI method has a potential to detect malignancies inside fibro-glandular tissue. PMID:25571382

  13. Precision lifetime measurements of exotic nuclei based on Doppler-shift techniques

    SciTech Connect

    Iwasaki, Hironori

    2013-04-19

    A recent progress in precision lifetime measurements of exotic nuclei at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University is presented. The Recoil Distance Doppler-shift (RDDS) technique has been applied to nuclear reactions involving intermediate-energy rare isotope (RI) beams, to determine absolute transition strengths between nuclear states model independently from level lifetimes of interest. As such an example, recent lifetime measurements of the first 2{sup +} states in the neutron-rich {sup 62,64,66}Fe isotopes at and around N=40 are introduced. The experiment was performed at the Coupled Cyclotron Facility at NSCL using a unique combination of several experimental instruments; the Segmented Germanium Array (SeGA), the plunger device, and the S800 spectrograph. The reduced E2 transition probabilities B(E2) are determined directly from the measured lifetimes. The observed trend of B(E2) clearly demonstrates that an enhanced collectivity persists in {sup 66}Fe despite the harmonic-oscillator magic number N=40. The present results are also discussed in comparison with the large-scale shell model calculations, pointing to a possible extension of the deformation region beyond N=40.

  14. Ultraviolet Properties of Halo Coronal Mass Ejections: Doppler Shifts, Angles, Shocks, and Bulk Morphology

    NASA Astrophysics Data System (ADS)

    Ciaravella, A.; Raymond, J. C.; Kahler, S. W.

    2006-11-01

    We present UV spectral information for 22 halo or partial halo CMEs observed by UVCS. The CME fronts show broad line profiles, while the line intensities are comparable to the background corona. The Doppler shifts of the front material are generally small, showing that the motion of gas in the fronts is mostly transverse to the line of sight. This indicates that, at least in halo CMEs, the fronts generally correspond to coronal plasma swept up by a shock or compression wave, rather than plasma carried outward by magnetic loops. This favors an ice cream cone (or a spherical shell) model, as opposed to an expanding arcade of loops. We use the line widths to discriminate between shock heating and bulk expansion. Of 14 cases where we detected the CME front, the line broadening in 7 cases can be attributed to shock heating, while in 3 cases it is the line-of-sight component of the CME expansion. For the CME cores we determine the angles between the motion and the plane of the sky, along with the actual heliocentric distances, in order to provide quantitative estimates of projection effects.

  15. Observation of Doppler-shifted T{alpha} emission from TFTR tritium neutral beams

    SciTech Connect

    Kamperschroer, J.H.; Grisham, L.R.; Lagin, L.J.; O`Connor, T.E.; Newman, R.A.; Stevenson, T.N.; von Halle, A.; Wright, K.E.

    1994-06-01

    195 tritium ion source shots were injected into TFTR high power plasmas during December 1993--March 1994. In addition, four highly diagnosed pulses were fired into the calorimeter. Analysis of the Doppler-shifted T{alpha} emission of the beam in the neutralizer has revealed that the extracted ion composition for deuterium and tritium are indistinguishable: 0.72{plus_minus}0.04 D{sup +}, 0.22{plus_minus}0.02 D{sub 2}{sup +}, 0.07{plus_minus}0.01 D{sub 3}{sup +} compared to 0.72{plus_minus}0.04 T{sup +}, 0.23{plus_minus}0.02 T{sub 2}{sup +}, 0.05{plus_minus}0.01 T{sub 3}{sup +}. The resultant tritium full-energy neutral fraction is higher than for deuterium due the increased neutralization efficiency at lower velocity. To conserve tritium, it was used only for injection and a few calorimeter test shots, never for ion source conditioning. When used, the gas species was switched to tritium only for the shot in question. This resulted in an approximately 2% deuterium contamination of the tritium beam and vice versa for the first deuterium pulse following tritium. Data from the calorimeter shots indicates that tritium contamination of the deuterium beam cleans up in 5--6 beam pulses, and is reduced to immeasurable quantities prior to deuterium beam injection.

  16. Multiple track Doppler-shift spectroscopy system for TFTR neutral beam injectors

    SciTech Connect

    Kamperschroer, J.H.; Kugel, H.W.; Reale, M.A.; Hayes, S.L.; Johnson, G.A.; Lowrance, J.L.; Shah, P.A.; Sichta, P.; Sleaford, B.W.; Williams, M.D.; Zucchino, P.M.

    1986-09-01

    A Doppler-shift spectroscopy system has been installed on the TFTR neutral beam injection system to measure species composition during both conditioning and injection pulses. Two intensified vidicon detectors and two spectrometers are utilized in a system capable of resolving data from up to twelve ion sources simultaneously. By imaging the light from six ion sources onto one detector, a cost-effective system has been achieved. Fiber optics are used to locate the diagnostic in an area remote from the hazards of the tokamak test cell allowing continuous access, and eliminating the need for radiation shielding of electronic components. Automatic hardware arming and interactive data analysis allow beam composition to be computed between tokamak shots for use in analyzing plasma heating experiments. Measurements have been made using lines of sight into both the neutralizer and the drift duct. Analysis of the data from the drift duct is both simpler and more accurate since only neutral particles are present in the beam at this location. Comparison of the data taken at these two locations reveals the presence of partially accelerated particles possessing an estimated 1/e half-angle divergence of 15/sup 0/ and accounting for up to 30% of the extracted power.

  17. Determination of solid-propellant transient regression rates using a microwave Doppler shift technique

    NASA Technical Reports Server (NTRS)

    Strand, L. D.; Schultz, A. L.; Reedy, G. K.

    1972-01-01

    A microwave Doppler shift system, with increased resolution over earlier microwave techniques, was developed for the purpose of measuring the regression rates of solid propellants during rapid pressure transients. A continuous microwave beam is transmitted to the base of a burning propellant sample cast in a metal waveguide tube. A portion of the wave is reflected from the regressing propellant-flame zone interface. The phase angle difference between the incident and reflected signals and its time differential are continuously measured using a high resolution microwave network analyzer and related instrumentation. The apparent propellant regression rate is directly proportional to this latter differential measurement. Experiments were conducted to verify the (1) spatial and time resolution of the system, (2) effect of propellant surface irregularities and compressibility on the measurements, and (3) accuracy of the system for quasi-steady-state regression rate measurements. The microwave system was also used in two different transient combustion experiments: in a rapid depressurization bomb, and in the high-frequency acoustic pressure environment of a T-burner.

  18. Doppler measurements of the ionosphere on the occasion of the Apollo-Soyuz test project. Part 2: Inversion of differential and rotating Doppler shifts

    NASA Technical Reports Server (NTRS)

    Gay, R. H.; Grossi, M. D.

    1975-01-01

    The preparation of the analytical approach and of the related software used in the inversion of the differential and rotating Doppler data obtained from the ionospheric experiment of the Apollo-Soyuz Test Project (ASTP) is discussed. These data were collected in space-to-space paths (between the ASTP Docking Module (DM) and the Apollo Command Service Module and in space-to-ground paths (between the DM and ground). The Doppler links operated at 162 and 324 MHz and have an accuracy better than 3 MHz over 10-sec integration time. The inversion approach was tested with dummy data obtained with a computer simulation. It was found that a measurement accuracy of 1 to 10% in the value of the horizontal electron density gradient at 221-km altitude can be achieved, in space-to-space paths. For space-to-ground paths near the orbital plane, possible effects of the horizontal gradients on the received differential Doppler shifts were identified. It was possible to reduce the gradient-associated errors in the inversion that leads to the columnar electron content by approximately one-half. Accuracies of 5 to 10% in columnar electron content are achievable, with this gradient-compensation technique.

  19. Doppler measurements of the ionosphere on the occasion of the Apollo-Soyuz test project. Part 1: Computer simulation of ionospheric-induced Doppler shifts

    NASA Technical Reports Server (NTRS)

    Grossi, M. D.; Gay, R. H.

    1975-01-01

    A computer simulation of the ionospheric experiment of the Apollo-Soyuz Test Project (ASTP) was performed. ASTP is the first example of USA/USSR cooperation in space and is scheduled for summer 1975. The experiment consists of performing dual-frequency Doppler measurements (at 162 and 324 MHz) between the Apollo Command Service Module (CSM) and the ASTP Docking Module (DM), both orbiting at 221-km height and at a relative distance of 300 km. The computer simulation showed that, with the Doppler measurement resolution of approximately 3 mHz provided by the instrumentation (in 10-sec integration time), ionospheric-induced Doppler shifts will be measurable accurately at all times, with some rare exceptions occurring when the radio path crosses regions of minimum ionospheric density. The computer simulation evaluated the ability of the experiment to measure changes of columnar electron content between CSM and DM (from which horizontal gradients of electron density at 221-km height can be obtained) and to measure variations in DM-to-ground columnar content (from which an averaged columnar content and the electron density at the DM can be deduced, under some simplifying assumptions).

  20. Wind Profile Retrieval Method for Incoherent Doppler LIDAR in Partly Cloudy Conditions

    NASA Astrophysics Data System (ADS)

    Feng, Changzhong; Liu, Bingyi; Liu, Zhishen

    2014-11-01

    After the launch of ESA’s spaceborne Doppler lidar ALADIN, Ocean University of China is going to perform the ground validation using a ground based Doppler wind lidar which utilizes an iodine absorption filter as frequency discriminator to derive Doppler frequency shift of atmospheric wind from combined molecular and aerosol backscatter. Under circumstance of non-uniform aerosol horizontal distribution, such as partly cloudy conditions, the accuracy of wind measurements is seriously influenced. Therefore, an improved VAD (Velocity-Azimuth Display) method for retrieving wind profiles is developed, which significantly increases the accuracy. With the atmospheric return signal obtained from the line-of-sight velocity PPI (Plan Position Indicator) measurements, the spatial distribution of aerosol optical parameters can be derived and considered as a reference for the quality control of line-of-sight velocity. Consequently, the wind profile in partly cloudy conditions can be retrieved by using the quality controlled line-of-sight velocity. As a result, the applicability of the ground based Doppler lidar is improved.

  1. Doppler methods of search and monitoring of exoplanets

    NASA Astrophysics Data System (ADS)

    Panchuk, V. E.; Klochkova, V. G.; Sachkov, M. E.; Yushkin, M. V.

    2015-12-01

    The main stages of the development of Doppler methods of search and study of extrasolar planetary systems (exoplanets) are described. The main instrumental and methodological effects that influence the measurement accuracy of spectral line positions in the study of exoplanets are considered. The development of the domestic spectrograph for spectroscopic monitoring with high-precision determination of radial velocities is reported. Directions for further development of high-resolution spectroscopy are discussed.

  2. O VI 1032 Å intensity and Doppler shift oscillations above a coronal hole: Magnetosonic waves or quasi-periodic upflows?

    NASA Astrophysics Data System (ADS)

    Mancuso, S.; Raymond, J. C.; Rubinetti, S.; Taricco, C.

    2016-08-01

    On 1996 December 19, the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO) conducted a special high-cadence sit-and-stare observation in the O vi 1032 Å spectral line above a polar coronal hole at a heliocentric distance of 1.38 R⊙. The ~ 9-h dataset was analyzed by applying advanced spectral techniques to investigate the possible presence of propagating waves. Highly significant oscillations in O vi intensity (P = 19.5 min) and Doppler shift (P = 7.2 min) were detected over two different portions of the UVCS entrance slit. A cross-correlation analysis between the O vi intensity and Doppler shift fluctuations shows that the most powerful oscillations were in phase or anti-phase over the same portions of the slit, thus providing a possible signature of propagating magnetosonic waves. The episodic nature of the observed oscillations and the large amplitudes of the Doppler shift fluctuations detected in our observations, if not attributable to line-of-sight effects or inefficient damping, may indicate that the observed fluctuations were produced by quasi-periodic upflows.

  3. Photoacoustic Doppler flowmetry of carbon particles flow using an autocorrelation method

    NASA Astrophysics Data System (ADS)

    Lu, Tao

    2014-09-01

    In order to measure the axial flowing velocity of a suspension carbon particles of tens of micometer-scale, the photoacoustic doppler frequency shift was calculated from a series of individual A scans using a autocorrelation method. A 532nm pulsed laser with the repetition rate of 20Hz was used as a pumping source to generate photoacoustic signal. The photoacoustic signals were detected using a focused PZT ultrasound transducer with central frequency of 5MHz. The suspension of carbon particles was driven by a syringe pump. Firstly, the complex photoacoustic signal was calculated by the Hilbert transformation from time-domain photoacoustic signal. The complex photoacoustic signal was then autocorrelated to calculate doppler frequency shift. The flow velocity was calculated by averaging the autocorrelation results of individual A scans. In comparison , the previously reported data processing methods using cross-correlation method in time domain or frequency domain require high sequential scanning rate or high laser repetition rate up to several kHz to avoid aliasing or uncorrelation between sequential waveform pairs. But it is difficult to get several kHz repetition rate for a single pulsed laser and the correlation between waveform pairs of sequential A scans were also limited by the laser repetition rate. To solve the problem, we used the autocorrelation method of individual A scans to calculated Doppler frequency shift. The time delay can be user defined to avoid aliasing. The feasibility of the proposed autocorrelation method was preliminarily demonstrated by quantifying the motion of a carbon particles suspension flow from 5 to 60 mm/s. The experimental results showed that the autocorrelation result approximately agreed with the setting velocity linearly.

  4. Pulsed photoacoustic Doppler flowmetry using a cross correlation method

    NASA Astrophysics Data System (ADS)

    Brunker, J.; Beard, P.

    2010-02-01

    The feasibility of making spatially resolved measurements of blood flow using pulsed photoacoustic Doppler techniques has been explored. Doppler time shifts were quantified via cross-correlation of pairs of photoacoustic waveforms generated within a blood-simulating phantom using pairs of laser light pulses. The photoacoustic waves were detected using a focussed or planar PZT ultrasound transducer. This approach was found to be effective for quantifying the linear motion of micron-scale absorbers imprinted on an acetate sheet moving with velocities in the range 0.15 to 1.50 ms-1. The effect of the acoustic spot diameter and the time separation between the laser pulses on measurement resolution and the maximum measurable velocity is discussed. The distinguishing advantage of pulsed rather than continuous-wave excitation is that spatially resolved velocity measurements can be made. This offers the prospect of mapping flow within the microcirculation and thus providing insights into the perfusion of tumours and other pathologies characterised by abnormalities in flow status.

  5. Doppler radar flowmeter

    DOEpatents

    Petlevich, Walter J.; Sverdrup, Edward F.

    1978-01-01

    A Doppler radar flowmeter comprises a transceiver which produces an audio frequency output related to the Doppler shift in frequency between radio waves backscattered from particulate matter carried in a fluid and the radiated radio waves. A variable gain amplifier and low pass filter are provided for amplifying and filtering the transceiver output. A frequency counter having a variable triggering level is also provided to determine the magnitude of the Doppler shift. A calibration method is disclosed wherein the amplifier gain and frequency counter trigger level are adjusted to achieve plateaus in the output of the frequency counter and thereby allow calibration without the necessity of being able to visually observe the flow.

  6. Planar Particle Imaging and Doppler Velocimetry System and Method

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P. (Inventor)

    2003-01-01

    A planar velocity measurement system (100) is operative to measure all three velocity components of a flowing fluid (106) across an illuminated plane (108) using only a single line of sight. The fluid flow is seeded with small particles which accurately follow the flow field fluctuations. The seeded flow field is illuminated with pulsed laser light source (102) and the positions of the particles in the flow are recorded on CCD cameras (122,124). The in-plane velocities are measured by determining the in-plane particle displacements. The out-of-plane velocity component is determined by measuring the Doppler shift of the light scattered by the particles. Both gas and liquid velocities can be measured, as well as two-phase flows.

  7. New signal analysis methods for laser doppler flowmetric recordings

    NASA Astrophysics Data System (ADS)

    ǎgǎnescu, G. E., Dr; Todea, Carmen

    2014-01-01

    The laser Doppler flowmetry devices give a series of information like the blood flux and some statistical parameters, automatically estimated. There are also new important attempts based on the Fourier transform of the flow flux signal which gather more information from the laser Doppler flowmetry. The amplitude spectra estimated in these articles, exhibit a series of peaks corresponding to the cardiac variation of the blood flow and noise components of the flow flux signals, dependent on the state of the tooth. The aim of our investigations is to introduce new signal processing methods, based on wavelet continuous tranform, which express in a more sensitive manner the modifications of the flow flux signal with the state of the tooth, and to introduce new quantitative parameters, defined in a previous paper. These parameters express, in a more sensitive manner the modifications of the pulp flow flux signal in relation with the pulp tooth healt, and to introduce new quantitative parameters, defined in a previous paper. These parameters express, in a sensitive way the changes of the blood flux. For practical investigations we used a series of signals recorded with the aid of a Laser Doppler Blood Flow Monitoring device (Moor Instruments) and processed with the computer.

  8. Azimuthal Doppler Effect in Optical Vortex Spectroscopy

    NASA Astrophysics Data System (ADS)

    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.

  9. Spinning disk calibration method and apparatus for laser Doppler velocimeter

    NASA Technical Reports Server (NTRS)

    Snyder, P. K. (Inventor)

    1986-01-01

    A method and apparatus for calibrating laser Doppler velocimeters having one or more intersecting beam pairs are described. These velocimeters measure fluid velocity by observing the light scattered by particles in the fluid stream. Moving fluid particulates are simulated by fine taut wires that are radially mounted on a disk that is rotated at a known velocity. The laser beam intersection locus is first aimed at the very center of the disk and then the disk is translated so that the locus is swept by the rotating wires. The radial distance traversed is precisely measured so that the velocity of the wires (pseudo particles) may be calculated.

  10. A relative performance analysis of atmospheric Laser Doppler Velocimeter methods.

    NASA Technical Reports Server (NTRS)

    Farmer, W. M.; Hornkohl, J. O.; Brayton, D. B.

    1971-01-01

    Evaluation of the effectiveness of atmospheric applications of a Laser Doppler Velocimeter (LDV) at a wavelength of about 0.5 micrometer in conjunction with dual scatter LDV illuminating techniques, or at a wavelength of 10.6 micrometer with local oscillator LDV illuminating techniques. Equations and examples are given to provide a quantitative basis for LDV system selection and performance criteria in atmospheric research. The comparative study shows that specific ranges and conditions exist where performance of one of the methods is superior to that of the other. It is also pointed out that great care must be exercised in choosing system parameters that optimize a particular LDV designed for atmospheric applications.

  11. Developing the Recoil Distance Doppler-Shift technique towards a versatile tool for lifetime measurements of excited nuclear states

    NASA Astrophysics Data System (ADS)

    Dewald, A.; Möller, O.; Petkov, P.

    2012-07-01

    In this article, the Recoil Distance Doppler-Shift (RDDS) method which is extensively used in nuclear structure physics to determine level lifetimes and absolute transition probabilities is reviewed. Especially, it is aimed to present new developments and variants of the technique which have evolved mainly in the past 25 years. After a short and comprehensive description of the basic elements of the plunger technique, the new variants are presented. This comprises the RDDS technique using γγ-coincidences, RDDS measurements in combination with particle detectors for selecting specific reaction channels, RDDS after Coulomb excitation, RDDS after fission and RDDS using a gas target. In addition, the concept of a differential plunger is discussed with respect to its specific features and typical experimental setups. Examples of differential plunger measurements with recoil tagging, recoil decay tagging and after deep inelastic reactions, Coulomb excitation in inverse reaction kinematics as well as after reactions with fast radioactive beams at energies of 50-100 MeV/u are given. The second focus of the review is dedicated to today’s plunger devices and related hardware. The concepts of specific plunger devices which accommodate the specific demands of the aforementioned RDDS applications including specific feedback systems for controlling target-stopper/degrader separations in-beam are presented. Also discussed are target and stopper/degrader foil related issues like foil preparation, mounting and stretching as well as specific features of the foil behavior in-beam (temperature, blistering, wrinkling and carbon build-up). The third focus is devoted to the data analysis. The concept of the Differential Decay Curve Method (DDCM) is presented as an alternative approach for the analysis of RDDS data measured as singles or as γγ-coincidences. For the latter, different gating possibilities are discussed, e.g. gating from above and gating from below the level of

  12. Dzyaloshinskii-Moriya Interaction as a Consequence of a Doppler Shift due to Spin-Orbit-Induced Intrinsic Spin Current

    NASA Astrophysics Data System (ADS)

    Kikuchi, Toru; Koretsune, Takashi; Arita, Ryotaro; Tatara, Gen

    2016-06-01

    We present a physical picture for the emergence of the Dzyaloshinskii-Moriya (DM) interaction based on the idea of the Doppler shift by an intrinsic spin current induced by spin-orbit interaction under broken inversion symmetry. The picture is confirmed by a rigorous effective Hamiltonian theory, which reveals that the DM coefficient is given by the magnitude of the intrinsic spin current. Our approach is directly applicable to first principles calculations and clarifies the relation between the interaction and the electronic band structures. Quantitative agreement with experimental results is obtained for the skyrmion compounds Mn1 -xFexGe and Fe1 -xCoxGe .

  13. Doppler-Free Spectroscopy Measurements of Isotope Shifts and Hyperfine Components of Near-IR Xenon Lines

    SciTech Connect

    Mazouffre, S.; Pawelec, E.; Tran Bich, N.; Sadeghi, N.

    2006-01-15

    Xenon is currently used as propellant gas in electric thrusters, in which ejection of corresponding ions produces the desired thrust. As such a gas contains 9 stable isotopes, a non-intrusive determination of the velocity distribution function of atoms and ions in the thruster plasma plume, by means of absorption or fluorescence techniques, requires a precise knowledge of the line structure. We used Doppler-free Lamb-dip spectroscopy to determine isotopic shifts and hyperfine components of odd isotopes of several spectral lines of Xe atom and Xe+ ion in the 825 - 835 nm range.

  14. Non-mechanical scanning laser Doppler velocimetry with sensitivity to direction of transverse velocity component using optical serrodyne frequency shifting

    NASA Astrophysics Data System (ADS)

    Maru, Koichi; Watanabe, Kento

    2014-05-01

    This paper proposes a non-mechanical axial scanning laser Doppler velocimeter (LDV) with sensitivity to the direction of the transverse velocity component using optical serrodyne frequency shifting. Serrodyne modulation via the electro-optic effect of a LiNbO3 (LN) phase shifter is employed to discriminate the direction of the transverse velocity component. The measurement position is scanned without any moving mechanism in the probe by changing the wavelength of the light input to the probe. The experimental results using a sensor probe setup indicate that both the scan of the measurement position and the introduction of directional sensitivity are successfully demonstrated.

  15. A frequency shift maximum frequency follower Doppler demodulator with amplitude correction.

    PubMed

    Follett, D H

    1981-11-01

    A commonly used maximum-frequency follower Doppler demodulator uses a variable-frequency voltage controlled filter that requires two good quality multipliers and can be difficult to set up and stabilise. An alternative presented here has the advantage of cheapness, easy setting-up and amplitude independence over about 25 dB giving the potential for quantitative as well as qualitative results. A switching modulator is first used to convert the Doppler spectrum into a pair of sidebands disposed about the modulating frequency. The modulation frequency is continually adjusted so that the lower sideband edge, representing the highest Doppler frequency, just passes the skirt of a low pass filter. The filter output, after rectification and smoothing, provides drive to the voltage controlled oscillator (VCO) generating the modulation frequency and also forms the flow signal output. The fixed low pass filter results in a stable feed-back loop in which high loop gain can be used so that linearity depends mostly on the VCO. The characteristic slope is independent of signal amplitude above a threshold, but increasing signal causes an increasing offset voltage. A simple signal rectifier enables this offset to be largely cancelled, giving amplitude independence. PMID:6765877

  16. Drift Velocity of Small-Scale Artificial Ionospheric Irregularities According to Multifrequency HF Doppler Radar. I. Method of Calculation and Its Hardware Implementation

    NASA Astrophysics Data System (ADS)

    Vertogradov, G. G.; Uryadov, V. P.; Vertogradov, V. G.; Vertogradova, E. G.; Kubatko, S. V.

    2015-10-01

    The method of calculating the total drift velocity vector of small-scale artificial ionospheric irregularities as measured by the effective Doppler frequency shift of aspect-scattered signals from several diagnostic illumination transmitters operated at different frequencies is discussed. The technique of adaptive simulation of decameter radio waves propagating in an inhomogeneous magnetized ionosphere with allowance for the aspect scattering effects due to small-scale field-aligned irregularities is developed. A multifrequency HF Doppler radar for simultaneous measurement of the Doppler spectra of radio signals at a set of frequencies is described.

  17. A comparison between coherent and noncoherent mobile systems in large Doppler shift, delay spread, and C/I environment

    NASA Technical Reports Server (NTRS)

    Feher, Kamilo

    1993-01-01

    The performance and implementation complexity of coherent and of noncoherent QPSK and GMSK modulation/demodulation techniques in a complex mobile satellite systems environment, including large Doppler shift, delay spread, and low C/I, are compared. We demonstrate that for large f(sub d)T(sub b) products, where f(sub d) is the Doppler shift and T(sub b) is the bit duration, noncoherent (discriminator detector or differential demodulation) systems have a lower BER floor than their coherent counterparts. For significant delay spreads, e.g., tau(sub rms) greater than 0.4 T(sub b), and low C/I, coherent systems outperform noncoherent systems. However, the synchronization time of coherent systems is longer than that of noncoherent systems. Spectral efficiency, overall capacity, and related hardware complexity issues of these systems are also analyzed. We demonstrate that coherent systems have a simpler overall architecture (IF filter implementation-cost versus carrier recovery) and are more robust in an RF frequency drift environment. Additionally, the prediction tools, computer simulations, and analysis of coherent systems is simpler. The threshold or capture effect in low C/I interference environment is critical for noncoherent discriminator based systems. We conclude with a comparison of hardware architectures of coherent and of noncoherent systems, including recent trends in commercial VLSI technology and direct baseband to RF transmit, RF to baseband (0-IF) receiver implementation strategies.

  18. Doppler and speckle methods for diagnostics in dentistry

    NASA Astrophysics Data System (ADS)

    Ulyanov, Sergey S.; Lepilin, Alexander V.; Lebedeva, Nina G.; Sedykh, Alexey V.; Kharish, Natalia A.; Osipova, Yulia; Karpovich, Alexander

    2002-02-01

    The results of statistical analysis of Doppler spectra of scattered intensity, obtained from tissues of oral cavity membrane of healthy volunteers, are presented. The dependence of the spectral moments of Doppler signal on cutoff frequency is investigated. Some results of statistical analysis of Doppler spectra, obtained from tooth pulp of patients, are presented. New approach for monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of measuring system on formation of speckle-interferometric signal is studied.

  19. Shifted power method for computing tensor eigenvalues.

    SciTech Connect

    Mayo, Jackson R.; Kolda, Tamara Gibson

    2010-07-01

    Recent work on eigenvalues and eigenvectors for tensors of order m >= 3 has been motivated by applications in blind source separation, magnetic resonance imaging, molecular conformation, and more. In this paper, we consider methods for computing real symmetric-tensor eigenpairs of the form Ax{sup m-1} = lambda x subject to ||x||=1, which is closely related to optimal rank-1 approximation of a symmetric tensor. Our contribution is a shifted symmetric higher-order power method (SS-HOPM), which we show is guaranteed to converge to a tensor eigenpair. SS-HOPM can be viewed as a generalization of the power iteration method for matrices or of the symmetric higher-order power method. Additionally, using fixed point analysis, we can characterize exactly which eigenpairs can and cannot be found by the method. Numerical examples are presented, including examples from an extension of the method to finding complex eigenpairs.

  20. Shifted power method for computing tensor eigenpairs.

    SciTech Connect

    Mayo, Jackson R.; Kolda, Tamara Gibson

    2010-10-01

    Recent work on eigenvalues and eigenvectors for tensors of order m {>=} 3 has been motivated by applications in blind source separation, magnetic resonance imaging, molecular conformation, and more. In this paper, we consider methods for computing real symmetric-tensor eigenpairs of the form Ax{sup m-1} = {lambda}x subject to {parallel}x{parallel} = 1, which is closely related to optimal rank-1 approximation of a symmetric tensor. Our contribution is a novel shifted symmetric higher-order power method (SS-HOPM), which we showis guaranteed to converge to a tensor eigenpair. SS-HOPM can be viewed as a generalization of the power iteration method for matrices or of the symmetric higher-order power method. Additionally, using fixed point analysis, we can characterize exactly which eigenpairs can and cannot be found by the method. Numerical examples are presented, including examples from an extension of the method to fnding complex eigenpairs.

  1. Accretion in young stars: measure of the stream velocity of TW Hya from the X-ray Doppler shift

    NASA Astrophysics Data System (ADS)

    Argiroffi, Costanza; Bonito, Rosaria; Orlando, Salvatore; Miceli, Marco; Peres, Giovanni

    2015-09-01

    High-resolution X-ray spectra are a unique tool to investigate the accretion process in young stars. In fact X-rays allow to investigate the accretion-shock region, where the infalling material is heated by strong shocks due to the impact with the denser stellar atmosphere. Here we show for the first time that it is possible to constrain the velocity of the accretion stream by measuring the Doppler shift of the emitted X-rays. To this aim we analyzed the deep Chandra/HETGS observation of the accreting young star TW Hya. We selected a sample of emission lines free from significant blends, fitted them with gaussian profiles, computed the radial velocity corresponding to each line, and averaged these velocities to obtain an accurate estimate of the global velocity of the X-ray emitting plasma. After correcting for Earth's motion, we compared this observed velocity with the photospheric radial velocity. In order to check this procedure we applied the same technique to other Chandra/HETGS spectra of single stars, whose X-rays are due only to coronal plasma. While spectra of pure coronal sources provide Doppler shifts in agreement with the known stellar radial velocity, we found that the X-ray spectrum of TW Hya is red-shifted by ~30-40 km/s with respect to the stellar photosphere. This proves that the X-ray emitting plasma on TW Hya is moving with respect to the stellar surface, definitively confirming that it originates in the accretion-shock region. The observed velocity suggests that the base of the accretion region is located at low latitudes of the stellar surface.

  2. Spread-spectrum code acquisition in the presence of Doppler shift and data modulation

    NASA Technical Reports Server (NTRS)

    Cheng, Unjeng; Hurd, William J.; Statman, Joseph I.

    1990-01-01

    A spread-spectrum code acquisition technique for a direct-sequence (DS) system in the presence of Doppler effect and data modulation is investigated. Both the carrier-frequency offset and code-frequency offset due to severe Doppler effect are considered. The code-chip slipping during the correlation process caused by code-frequency offset can degrade the acquisition performance significantly. However, this issue can be alleviated by compensating code-frequency offset in an appropriate manner. Results are presented for the cases with and without data modulation. Coherent detection is considered when there is no data modulation. If data modulation is present, the authors partition the correlation time into subintervals and the integration results in these subintervals are square-law noncoherently combined for detection. The implementation of this code acquisition technique using the fast Fourier transform (FFT) algorithm is described. The use of theoretical results to estimate the hardware complexity of an actual system is illustrated step by step, showing that implementation is feasible with existing technology. The tradeoff between hardware complexity and acquisition performance is discussed.

  3. Application of the multiple signal classification (MUSIC) method for one-pulse burst-echo Doppler sonar data

    NASA Astrophysics Data System (ADS)

    Iwata, Tetsuo; Goto, Yoji; Susaki, Hironori

    2001-12-01

    In order to estimate ship velocity, we have applied the multiple signal classification (MUSIC) method to one-pulse burst-echo Doppler sonar data. The MUSIC method enabled us to estimate the Doppler frequency shift precisely under a low-signal-to-noise ratio (SNR) situation even from a one-pulse burst-echo signal with small data points. In simulation experiments, a signal frequency component of f = 16 Hz could be extracted from N = 128 data-point data under a 40% Gaussian-distributed additive noise with a sampling frequency fs = 2048 Hz. From actual one-pulse burst-echo signal data of N = 128 points, a Doppler frequency shift of Δf = 1.45 kHz, corresponding to a ship velocity 1.76 knots, was clearly detected, the frequency resolution of which was almost impossible to attain by the conventional Fourier transform (FFT) method. We found that the MUSIC method was useful especially for estimating the ship velocity at a very low speed.

  4. Accuracy of velocity and power determination by the Doppler method

    NASA Technical Reports Server (NTRS)

    Rottger, J.

    1984-01-01

    When designing a Mesosphere-Stratosphere-Troposphere (MST) radar antenna one has to trade between the choices to optimize the effective aperture or to optimize the sidelobe suppression. An optimization of the aperture increases the sensitivity. Suppression of side-lobes by tapering attenuates undesirable signals which spoil the estimates of reflectivity and velocity. Generally, any sidelobe effects are equivalent to a broadening of the antenna beam. The return signal is due to a product of the antenna pattern with the varying atmospheric reflectivity structures. Thus, knowing the antenna pattern, it is in principle possible to find the signal spectra, which, however, may be a tedious computational and ambiguous procedure. For vertically pointing main beams the sidelobe effects are efficiently suppressed because of the aspect sensitivity. It follows that sidelobes are a minor problem for spaced antenna methods. However, they can be crucial for Doppler methods, which need off-vertical beams. If a sidelobe is pointing towards the zenith a larger power may be received from the vertical than off-vertical directions, but quantitative estimates of this effect are not yet known. To get an error estimate of sidelobe effects with an off-vertical main beam a 1-dimensional example is considered.

  5. Seismo traveling ionospheric disturbances of HF Doppler shift triggered by the 2011 M9.0 Tohoku earthquake observed in Taiwan

    NASA Astrophysics Data System (ADS)

    Chou, M.; Liu, J. G.

    2011-12-01

    M.Y. Chou 996203012@cc.ncu.edu.tw Institute of Space Science, National Central University, Chung-li, Taiwan J.Y. Liu jyliu@jupiter.ss.ncu.edu.tw Institute of Space Science, National Central University, Chung-li, Taiwan A network of digital HF Doppler sounding system in Taiwan is used to study seismo traveling ionospheric disturbances (STIDs) triggered by an earthquake of magnitude 9.0 occurring near the east coast of Honshu (Tohoku area) in Japan on 11 March 2011. Clear STIDs consist of a package of short-period Doppler shifts, which yield vertical ionospheric fluctuations with a maximum velocity of about 120m/s. An angle of arrival analysis and the circle method are use to estimate the propagation velocity and located the STID origin. Results show that the STIDs are excited by the Rayleigh waves, which quickly propagate away from the origin near the reported epicenter with a speed about 2.3-3.3 km/s.

  6. Optical Filters to Exclude Non-Doppler-Shifted Light in Fast Velocimetry

    SciTech Connect

    Goosman, D; Avara, G; Wade, J; Rivera, A

    2002-06-19

    We have used optical velocimetry for 25 years at LLNL to measure velocity-time histories of many dynamic experiments. In certain ones, the shifted light was often quite weak compared to non-shifted light returning from surfaces and imperfections in glass components. In an intensity-measuring VISAR system, this would mean failure, and even with Fabry-Perot (FP) based systems which handle multiple frequencies, data is lost where the fringes coincide. We designed, constructed and successfully used an experimental facility for doing experiments under such conditions by selectively eliminating most of the non-shifted light. Instead of making experimental records which were mostly non-shifted light prior to the use of the filter, we now obtain records where almost all of the light is shifted. The first system had a maximum efficiency of 25% for the desired light, but another version is under construction with a maximum efficiency of over 50%. The first version excluded the non-shifted light by a factor of 300 when manually tuned, and by 150 when run in a Window-based auto-tuning mode. Our first version used a 50 mm diameter FP as the filter with a spacing of 1.65 mm and reflectivities of 77%. It was constructed for use in one of our 5-beam velocimeters. Rather than using five separate filters, we multiplexed all five records so that the desired light would reflect from the filter FPl and image onto separate fibers. These five output fibers then fed our standard tau-table with 5 cameras as described in our report for the 1996 HSPC in Santa Fe, USA. One use of the filter system involved embedding optical fibers in long sections of explosives to make continuous detonation velocity-time histories. To date we have recently carried out 6 tests with this new facility, and two prior ones without. Explosive safety required that four shutters be used to assure that no significant light could illuminate the explosive from the end of the embedded fiber when personnel were close. An

  7. Development of the doppler electron velocimeter: theory.

    SciTech Connect

    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. Doppler wavelength shifts of transition zone lines measured in Skylab solar spectra

    NASA Technical Reports Server (NTRS)

    Doschek, G. A.; Bohlin, J. D.; Feldman, U.

    1976-01-01

    Wavelengths of lines of the transition-zone ions Si IV, C IV, O IV, N V, and O V are observed to be redshifted relative to the wavelengths of chromospheric lines in XUV spectra obtained from the normal-incidence spectrograph on Skylab. The spectra cover the wavelength range from 1200 to 1565 A and were obtained with the slit positioned over chromospheric network and cell regions, on coronal holes, and above the limb. The network-area and coronal-hole spectra were obtained near the disk center. Only some of the spectra show redshifted transition-zone lines. The observed shifts are between 0.03 and 0.08 A, implying velocities of 15 km/s or less. The amount of wavelength shift does not always appear to be the same for lines of different ions. The shifts imply that descending plasma in the solar atmosphere produces more emission than ascending plasma at temperatures between approximately 70,000 and 200,000 K.

  9. Wind turbines and bat mortality: Doppler shift profiles and ultrasonic bat-like pulse reflection from moving turbine blades.

    PubMed

    Long, Chloe V; Flint, James A; Lepper, Paul A

    2010-10-01

    Bat mortality resulting from actual or near-collision with operational wind turbine rotors is a phenomenon that is widespread but not well understood. Because bats rely on information contained in high-frequency echoes to determine the nature and movement of a target, it is important to consider how ultrasonic pulses similar to those used by bats for echolocation may be interacting with operational turbine rotor blades. By assessing the characteristics of reflected ultrasonic echoes, moving turbine blades operating under low wind speed conditions (<6 m s(-1)) were found to produce distinct Doppler shift profiles at different angles to the rotor. Frequency shifts of up to ±700-800 Hz were produced, which may not be perceptible by some bat species. Monte Carlo simulation of bat-like sampling by echolocation revealed that over 50 rotor echoes could be required by species such as Pipistrellus pipistrellus for accurate interpretation of blade movement, which may not be achieved in the bat's approach time-window. In summary, it was found that echoes returned from moving blades had features which could render them attractive to bats or which might make it difficult for the bat to accurately detect and locate blades in sufficient time to avoid a collision. PMID:20968394

  10. Performance of short-time spectral parametric methods for reducing the variance of the Doppler ultrasound mean instantaneous frequency estimation.

    PubMed

    Sava, H; Durand, L G; Cloutier, G

    1999-05-01

    To achieve an accurate estimation of the instantaneous turbulent velocity fluctuations downstream of prosthetic heart valves in vivo, the variability of the spectral method used to measure the mean frequency shift of the Doppler signal (i.e. the Doppler velocity) should be minimised. This paper investigates the performance of various short-time spectral parametric methods such as the short-time Fourier transform, autoregressive modelling based on two different approaches, autoregressive moving average modelling based on the Steiglitz-McBride method, and Prony's spectral method. A simulated Doppler signal was used to evaluate the performance of the above mentioned spectral methods and Gaussian noise was added to obtain a set of signals with various signal-to-noise ratios. Two different parameters were used to evaluate the performance of each method in terms of variability and accurate matching of the theoretical Doppler mean instantaneous frequency variation within the cardiac cycle. Results show that autoregressive modelling outperforms the other investigated spectral techniques for window lengths varying between 1 and 10 ms. Among the autoregressive algorithms implemented, it is shown that the maximum entropy method based on a block data processing technique gives the best results for a signal-to-noise ratio of 20 dB. However, at 10 and 0 dB, the Levinson-Durbin algorithm surpasses the performance of the maximum entropy method. It is expected that the intrinsic variance of the spectral methods can be an important source of error for the estimation of the turbulence intensity. The range of this error varies from 0.38% to 24% depending on the parameters of the spectral method and the signal-to-noise ratio. PMID:10505377

  11. Usage of eigenvector methods to improve reliable classifier for Doppler ultrasound signals.

    PubMed

    Ubeyli, Elif Derya

    2008-05-01

    A new approach based on the implementation of the automated diagnostic systems for Doppler ultrasound signals classification with the features extracted by eigenvector methods is presented. In practical applications of pattern recognition, there are often diverse features extracted from raw data which needs recognizing. Because of the importance of making the right decision, the present work is carried out for searching better classification procedures for the Doppler ultrasound signals. Decision making was performed in two stages: feature extraction by the eigenvector methods and classification using the classifiers trained on the extracted features. The aim of the study is classification of the Doppler ultrasound signals by the combination of eigenvector methods and the classifiers. The present research demonstrated that the power levels of the power spectral density (PSD) estimates obtained by the eigenvector methods are the features which well represent the Doppler ultrasound signals and the probabilistic neural networks (PNNs), recurrent neural networks (RNNs) trained on these features achieved high classification accuracies. PMID:18358461

  12. PERSISTENT DOPPLER SHIFT OSCILLATIONS OBSERVED WITH HINODE/EIS IN THE SOLAR CORONA: SPECTROSCOPIC SIGNATURES OF ALFVENIC WAVES AND RECURRING UPFLOWS

    SciTech Connect

    Tian Hui; McIntosh, Scott W.; Wang, Tongjiang; Ofman, Leon; De Pontieu, Bart; Innes, Davina E.; Peter, Hardi

    2012-11-10

    Using data obtained by the EUV Imaging Spectrometer on board Hinode, we have performed a survey of obvious and persistent (without significant damping) Doppler shift oscillations in the corona. We have found mainly two types of oscillations from February to April in 2007. One type is found at loop footpoint regions, with a dominant period around 10 minutes. They are characterized by coherent behavior of all line parameters (line intensity, Doppler shift, line width, and profile asymmetry), and apparent blueshift and blueward asymmetry throughout almost the entire duration. Such oscillations are likely to be signatures of quasi-periodic upflows (small-scale jets, or coronal counterpart of type-II spicules), which may play an important role in the supply of mass and energy to the hot corona. The other type of oscillation is usually associated with the upper part of loops. They are most clearly seen in the Doppler shift of coronal lines with formation temperatures between one and two million degrees. The global wavelets of these oscillations usually peak sharply around a period in the range of three to six minutes. No obvious profile asymmetry is found and the variation of the line width is typically very small. The intensity variation is often less than 2%. These oscillations are more likely to be signatures of kink/Alfven waves rather than flows. In a few cases, there seems to be a {pi}/2 phase shift between the intensity and Doppler shift oscillations, which may suggest the presence of slow-mode standing waves according to wave theories. However, we demonstrate that such a phase shift could also be produced by loops moving into and out of a spatial pixel as a result of Alfvenic oscillations. In this scenario, the intensity oscillations associated with Alfvenic waves are caused by loop displacement rather than density change. These coronal waves may be used to investigate properties of the coronal plasma and magnetic field.

  13. Persistent Doppler Shift Oscillations Observed with HINODE-EIS in the Solar Corona: Spectroscopic Signatures of Alfvenic Waves and Recurring Upflows

    NASA Technical Reports Server (NTRS)

    Tian, Hui; McIntosh, Scott W.; Wang, Tongjiang; Offman, Leon; De Pontieu, Bart; Innes, Davina E.; Peter, Hardi

    2012-01-01

    Using data obtained by the EUV Imaging Spectrometer on board Hinode, we have performed a survey of obvious and persistent (without significant damping) Doppler shift oscillations in the corona. We have found mainly two types of oscillations from February to April in 2007. One type is found at loop footpoint regions, with a dominant period around 10 minutes. They are characterized by coherent behavior of all line parameters (line intensity, Doppler shift, line width, and profile asymmetry), and apparent blueshift and blueward asymmetry throughout almost the entire duration. Such oscillations are likely to be signatures of quasi-periodic upflows (small-scale jets, or coronal counterpart of type-II spicules), which may play an important role in the supply of mass and energy to the hot corona. The other type of oscillation is usually associated with the upper part of loops. They are most clearly seen in the Doppler shift of coronal lines with formation temperatures between one and two million degrees. The global wavelets of these oscillations usually peak sharply around a period in the range of three to six minutes. No obvious profile asymmetry is found and the variation of the line width is typically very small. The intensity variation is often less than 2%. These oscillations are more likely to be signatures of kink/Alfv´en waves rather than flows. In a few cases, there seems to be a p/2 phase shift between the intensity and Doppler shift oscillations, which may suggest the presence of slow-mode standing waves according to wave theories. However, we demonstrate that such a phase shift could also be produced by loops moving into and out of a spatial pixel as a result of Alfv´enic oscillations. In this scenario, the intensity oscillations associated with Alfv´enic waves are caused by loop displacement rather than density change. These coronal waves may be used to investigate properties of the coronal plasma and magnetic field.

  14. 3D reconstruction and quantitative assessment method of mitral eccentric regurgitation from color Doppler echocardiography

    NASA Astrophysics Data System (ADS)

    Liu, Qi; Ge, Yi Nan; Wang, Tian Fu; Zheng, Chang Qiong; Zheng, Yi

    2005-10-01

    Based on the two-dimensional color Doppler image in this article, multilane transesophageal rotational scanning method is used to acquire original Doppler echocardiography while echocardiogram is recorded synchronously. After filtering and interpolation, the surface rendering and volume rendering methods are performed. Through analyzing the color-bar information and the color Doppler flow image's superposition principle, the grayscale mitral anatomical structure and color-coded regurgitation velocity parameter were separated from color Doppler flow images, three-dimensional reconstruction of mitral structure and regurgitation velocity distribution was implemented separately, fusion visualization of the reconstructed regurgitation velocity distribution parameter with its corresponding 3D mitral anatomical structures was realized, which can be used in observing the position, phase, direction and measuring the jet length, area, volume, space distribution and severity level of the mitral regurgitation. In addition, in patients with eccentric mitral regurgitation, this new modality overcomes the inherent limitations of two-dimensional color Doppler flow image by depicting the full extent of the jet trajectory, the area of eccentric regurgitation on three-dimensional image was much larger than that on two-dimensional image, the area variation tendency and volume variation tendency of regurgitation have been shown in figure at different angle and different systolic phase. The study shows that three-dimensional color Doppler provides quantitative measurements of eccentric mitral regurgitation that are more accurate and reproducible than conventional color Doppler.

  15. Self-induced transparency scenario revisited via beat-wave heating induced by Doppler shift in overdense plasma layer

    SciTech Connect

    Ghizzo, A.; Del Sarto, D.; Reveille, T.; Besse, N.; Klein, R.

    2007-06-15

    Maxwell-fluid simulations on a flat-topped moderately overdense plasma slab (typically n{sub 0}/n{sub c}=1-2) by Berezhiani et al. [Phys. Plasmas 66, 062308 (2005)] (see also the previous work of Tushentsov et al. [Phys. Rev. Lett. 87, 275002 (2001)]) were seen to lead to dynamic penetration of an ultrahigh intensity laser pulse into an overdense plasma. Two qualitatively different scenarios for the penetration of laser pulse into the overdense plasma were presented depending on the background density. In the first one, the penetration of laser energy occurs by soliton-like structures moving into the plasma. In the last one, electron cavitation occurs and the penetration is possible over a finite length only. A kinetic extension is made in this paper using Vlasov-Maxwell simulations. Vlasov simulations revealed a rich variety of new phenomena associated with the trapped particle dynamics, which cannot be described in fluid models. Most notably is the observation, during the penetration phase of the pump electromagnetic wave, of a beat-wave heating scenario induced by the Doppler shift on the reflected wave at the (moving) wave front. This beat-wave generates low-frequency acoustic-like electron modes characterized by coherent trapping-type structures in phase space leading to an efficient (nonstochastic) heating process.

  16. Combining eigenvector methods and support vector machines for detecting variability of Doppler ultrasound signals.

    PubMed

    Ubeyli, Elif Derya

    2007-05-01

    In this paper, the multiclass support vector machines (SVMs) with the error correcting output codes (ECOC) were presented for detecting variabilities of the multiclass Doppler ultrasound signals. The ophthalmic arterial (OA) Doppler signals were recorded from healthy subjects, subjects suffering from OA stenosis, subjects suffering from ocular Behcet disease. The internal carotid arterial (ICA) Doppler signals were recorded from healthy subjects, subjects suffering from ICA stenosis, subjects suffering from ICA occlusion. Methods of combining multiple classifiers with diverse features are viewed as a general problem in various application areas of pattern recognition. Because of the importance of making the right decision, better classification procedures for Doppler ultrasound signals are searched. Decision making was performed in two stages: feature extraction by eigenvector methods and classification using the SVMs trained on the extracted features. The research demonstrated that the multiclass SVMs trained on extracted features achieved high accuracy rates. PMID:17289211

  17. ON THE DOPPLER SHIFT AND ASYMMETRY OF STOKES PROFILES OF PHOTOSPHERIC Fe I AND CHROMOSPHERIC Mg I LINES

    SciTech Connect

    Na Deng; Choudhary, Debi Prasad; Balasubramaniam, K. S. E-mail: debiprasad.choudhary@csun.ed

    2010-08-10

    We analyzed the full Stokes spectra using simultaneous measurements of the photospheric (Fe I 630.15 and 630.25 nm) and chromospheric (Mg I b {sub 2} 517.27 nm) lines. The data were obtained with the High Altitude Observatory/National Solar Observatory (HAO/NSO) advanced Stokes polarimeter, about a near disk center sunspot region, NOAA AR 9661. We compare the characteristics of the Stokes profiles in terms of Doppler shifts and asymmetries among the three spectral lines, helping us to better understand the chromospheric lines and the magnetic and flow fields in different magnetic regions. The main results are: (1) for the penumbral area observed by the photospheric Fe I lines, Doppler velocities derived from Stokes I ({nu} {sub i}) are very close to those derived from linear polarization profiles ({nu}{sub lp}) but significantly different from those derived from Stokes V profiles ({nu}{sub zc}), thus providing direct and strong evidence that the penumbral Evershed flows are magnetized and mainly carried by the horizontal magnetic component; (2) the rudimentary inverse Evershed effect observed by the Mg I b {sub 2} line provides qualitative evidence on its formation height that is around or just above the temperature minimum region; (3) {nu}{sub zc} and {nu}{sub lp} in the penumbrae and {nu}{sub zc} in the pores generally approach their {nu} {sub i} observed by the chromospheric Mg I line, which is not the case for the photospheric Fe I lines; (4) the outer penumbrae and pores show similar Stokes V asymmetry behavior that tend to change from positive values in the photosphere (Fe I lines) to negative values in the low chromosphere (Mg I line); (5) the Stokes V profiles in plage regions are highly asymmetric in the photosphere and more symmetric in the low chromosphere; and (6) strong redshifts and large asymmetries are found around the magnetic polarity inversion line within the common penumbra of the {delta} spot. We offer explanations or speculations to the

  18. The observation at Chofu of Doppler-shifts of subionospheric LF signal transmitted from Saga, and the mechanism of lithosphere- atmosphere-ionosphere coupling

    NASA Astrophysics Data System (ADS)

    Hayakawa, M.; Kasahara, Y.; Endoh, T.; Hobara, Y.; Asai, S.

    2012-04-01

    This paper is based on the measurement at Chofu(CHF) of subionospheric signals from an LF transmitter, JJY (frequency=60kHz) (transmitted from Saga, Kyushu). The data analysis was done for the 6-month period from January 1, 2009 to June 30, 2009, during which several earthquakes happened near the propagation path of JJY-CHF. The Doppler-shifts of subionospheric LF signals are considered to provide the significant direct information in the lower ionosphere. It is found that we could detect the significant increase in the AGW and AW components of Doppler-shifts several days before each earthquake. This fact provides a definite strong support to the AGW channel of the lithosphere-atmosphere-ionosphere-coupling.

  19. Vector Doppler Method Based on an Automatic Transverse Angle Tracking Procedure

    NASA Astrophysics Data System (ADS)

    Dallai, A.; Boni, E.; Francalanci, L.; Tortoli, P.

    Traditional Doppler methods only measure the axial component of the velocity vector. The lack of information on the beam-to-flow (Doppler) angle creates an ambiguity which can lead to large errors in velocity magnitude estimates. An original approach was recently introduced, in which two ultrasound beams with known relative orientation are directed towards the same vessel, one being committed to perform a Doppler measurement, while the second beam has the specific task of detecting the beam-to-flow angle. In this paper, an angle-tracking procedure allowing the Doppler angle to be automatically determined with high accuracy is presented. The procedure is based on the real-time estimation of suitable Doppler spectrum parameters obtained from an M-line associated to a sub-aperture of a linear array probe. Such parameters are used to steer the M-line towards a direction corresponding to a desired beam-flow angle. Knowledge of this angle is finally exploited to obtain the velocity magnitude through the classic Doppler equation related to the second beam. The implementation of the method on a new ultrasound machine and its validation through in vitro and in vivo tests are reported.

  20. Method and apparatus for ultrasonic doppler velocimetry using speed of sound and reflection mode pulsed wideband doppler

    DOEpatents

    Shekarriz, Alireza; Sheen, David M.

    2000-01-01

    According to the present invention, a method and apparatus rely upon tomographic measurement of the speed of sound and fluid velocity in a pipe. The invention provides a more accurate profile of velocity within flow fields where the speed of sound varies within the cross-section of the pipe. This profile is obtained by reconstruction of the velocity profile from the local speed of sound measurement simultaneously with the flow velocity. The method of the present invention is real-time tomographic ultrasonic Doppler velocimetry utilizing a to plurality of ultrasonic transmission and reflection measurements along two orthogonal sets of parallel acoustic lines-of-sight. The fluid velocity profile and the acoustic velocity profile are determined by iteration between determining a fluid velocity profile and measuring local acoustic velocity until convergence is reached.

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

    SciTech Connect

    Welch, E. C.; Zhang, P.; He, Z.-H.; Dollar, F.; Krushelnick, K.; Thomas, A. G. R.

    2015-05-15

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

  2. Equivalent width evaluation methods for Doppler, Lorentz, and Voigt profiles.

    PubMed

    Habib, Abdel Aziz M; Rammah, Yasser S

    2014-01-01

    An accurate technique has been developed to calculate the equivalent width of absorption lines. The calculations have been carried out for the pure Doppler and pure Lorentz limiting forms of the equivalent width. A novel expression for the equivalent width for Lorentz profile is given from direct integration of the line profile. The more general case of a Voigt profile leads to an analytical formula that permits a rapid estimate of the equivalent width for a wide range of maximum optical depths. The reliability of the approach is verified using a numerical application calculating the equivalent width for nickel resonance lines at 232.0 and 352.3 nm from atomic absorption (AA) measurements. The dependence of equivalent width on the number density of absorbing atoms is also provided. The results obtained for the equivalent width for the Voigt profile were compared with the data in the available literature obtained by different approaches. PMID:24480275

  3. A comprehensive method of estimating electric fields from vector magnetic field and Doppler measurements

    SciTech Connect

    Kazachenko, Maria D.; Fisher, George H.; Welsch, Brian T.

    2014-11-01

    Photospheric electric fields, estimated from sequences of vector magnetic field and Doppler measurements, can be used to estimate the flux of magnetic energy (the Poynting flux) into the corona and as time-dependent boundary conditions for dynamic models of the coronal magnetic field. We have modified and extended an existing method to estimate photospheric electric fields that combines a poloidal-toroidal decomposition (PTD) of the evolving magnetic field vector with Doppler and horizontal plasma velocities. Our current, more comprehensive method, which we dub the 'PTD-Doppler-FLCT Ideal' (PDFI) technique, can now incorporate Doppler velocities from non-normal viewing angles. It uses the FISHPACK software package to solve several two-dimensional Poisson equations, a faster and more robust approach than our previous implementations. Here, we describe systematic, quantitative tests of the accuracy and robustness of the PDFI technique using synthetic data from anelastic MHD (ANMHD) simulations, which have been used in similar tests in the past. We find that the PDFI method has less than 1% error in the total Poynting flux and a 10% error in the helicity flux rate at a normal viewing angle (θ = 0) and less than 25% and 10% errors, respectively, at large viewing angles (θ < 60°). We compare our results with other inversion methods at zero viewing angle and find that our method's estimates of the fluxes of magnetic energy and helicity are comparable to or more accurate than other methods. We also discuss the limitations of the PDFI method and its uncertainties.

  4. Optimization of Doppler velocity echocardiographic measurements using an automatic contour detection method.

    PubMed

    Gaillard, E; Kadem, L; Pibarot, P; Durand, L-G

    2009-01-01

    Intra- and inter-observer variability in Doppler velocity echocardiographic measurements (DVEM) is a significant issue. Indeed, imprecisions of DVEM can lead to diagnostic errors, particularly in the quantification of the severity of heart valve dysfunction. To minimize the variability and rapidity of DVEM, we have developed an automatic method of Doppler velocity wave contour detection, based on active contour models. To validate our new method, results obtained with this method were compared to those obtained manually by an experienced echocardiographer on Doppler echocardiographic images of left ventricular outflow tract and transvalvular flow velocity signals recorded in 30 patients, 15 with aortic stenosis and 15 with mitral stenosis. We focused on three essential variables that are measured routinely by Doppler echocardiography in the clinical setting: the maximum velocity, the mean velocity and the velocity-time integral. Comparison between the two methods has shown a very good agreement (linear correlation coefficient R(2) = 0.99 between the automatically and the manually extracted variables). Moreover, the computation time was really short, about 5s. This new method applied to DVEM could, therefore, provide a useful tool to eliminate the intra- and inter-observer variabilities associated with DVEM and thereby to improve the diagnosis of cardiovascular disease. This automatic method could also allow the echocardiographer to realize these measurements within a much shorter period of time compared to standard manual tracing method. From a practical point of view, the model developed can be easily implanted in a standard echocardiographic system. PMID:19965162

  5. Analysis of a Four-Station Doppler Tracking Method Using a Simple CW Beacon

    NASA Technical Reports Server (NTRS)

    Fricke, Clifford L.; Watkins, Carl W. L.

    1961-01-01

    A Doppler tracking method is presented in which a very small, simple CW beacon transmitter is used with four Doppler receiving stations to obtain the position and velocity of a space research vehicle. The exact transmitter frequency need not be known, but an initial position is required, and Doppler frequencies must be measured with extreme accuracy. The errors in the system are analyzed and general formulas are derived for position and velocity errors. The proper location of receiving stations is discussed, a rule for avoiding infinite errors is given, and error charts for ideal station configurations are presented. The effect of the index of refraction is also investigated. The system is capable of determining transmitter position within 1,000 feet at a range of 200 miles.

  6. Error Correction Method for Wind Speed Measured with Doppler Wind LIDAR at Low Altitude

    NASA Astrophysics Data System (ADS)

    Liu, Bingyi; Feng, Changzhong; Liu, Zhishen

    2014-11-01

    For the purpose of obtaining global vertical wind profiles, the Atmospheric Dynamics Mission Aeolus of European Space Agency (ESA), carrying the first spaceborne Doppler lidar ALADIN (Atmospheric LAser Doppler INstrument), is going to be launched in 2015. DLR (German Aerospace Center) developed the A2D (ALADIN Airborne Demonstrator) for the prelaunch validation. A ground-based wind lidar for wind profile and wind field scanning measurement developed by Ocean University of China is going to be used for the ground-based validation after the launch of Aeolus. In order to provide validation data with higher accuracy, an error correction method is investigated to improve the accuracy of low altitude wind data measured with Doppler lidar based on iodine absorption filter. The error due to nonlinear wind sensitivity is corrected, and the method for merging atmospheric return signal is improved. The correction method is validated by synchronous wind measurements with lidar and radiosonde. The results show that the accuracy of wind data measured with Doppler lidar at low altitude can be improved by the proposed error correction method.

  7. The Effect of Doppler Frequency Shift, Frequency Offset of the Local Oscillators, and Phase Noise on the Performance of Coherent OFDM Receivers

    NASA Technical Reports Server (NTRS)

    Xiong, Fuqin; Andro, Monty

    2001-01-01

    This paper first shows that the Doppler frequency shift affects the frequencies of the RF carrier, subcarriers, envelope, and symbol timing by the same percentage in an Orthogonal Frequency Division Multiplexing (OFDM) signal or any other modulated signals. Then the SNR degradation of an OFDM system due to Doppler frequency shift, frequency offset of the local oscillators and phase noise is analyzed. Expressions are given and values for 4-, 16-, 64-, and 256-QAM OFDM systems are calculated and plotted. The calculations show that the Doppler shift of the D3 project is about 305 kHz, and the degradation due to it is about 0.01 to 0.04 dB, which is negligible. The degradation due to frequency offset and phase noise of local oscillators will be the main source of degradation. To keep the SNR degradation under 0.1 dB, the relative frequency offset due to local oscillators must be below 0.01 for the 16 QAM-OFDM. This translates to an offset of 1.55 MHz (0.01 x 155 MHz) or a stability of 77.5 ppm (0.01 x 155 MHz/20 GHz) for the DI project. To keep the SNR degradation under 0.1 dB, the relative linewidth (0) due to phase noise of the local oscillators must be below 0.0004 for the 16 QAM-OFDM. This translates to a linewidth of 0.062 MHz (0.0004 x 155 MHz) of the 20 GHz RIF carrier. For a degradation of 1 dB, beta = 0.04, and the linewidth can be relaxed to 6.2 MHz.

  8. New Method for Light Shift Elimination in Optical Pumping Systems

    NASA Astrophysics Data System (ADS)

    McGuyer, Bart; Jau, Yuan-Yu; Happer, William

    2009-05-01

    We present a new method to eliminate the light shift in atomic frequency standards and other optical pumping systems. This method uses only frequency modulation of a radio frequency or microwave source in order to simultaneously lock the source frequency to an atomic resonance and lock the pumping light to eliminate the light shift. In contrast, conventional stabilization of both sources requires two individual modulation schemes and feedback loops, adding complexity. Our method kills two birds with one stone. The method uses fewer additional components and offers improved performance, reduced cost, and easier miniaturization than previous methods. In particular, few modifications are required for implementation in conventional vapor-cell atomic clocks. We believe this technique will be useful for atomic frequency standards and other optical pumping systems that experience the light shift. We will present experimental results validating this method in a vapor-cell clock, and will also present numerical results verifying this method.

  9. An in situ method for diagnosing phase shifting interferometry

    NASA Astrophysics Data System (ADS)

    Shao, J.; Ma, D.; Zhang, H.; Xie, Y.

    2016-05-01

    Current diagnosing phase shifting interferometry is a time and funds consuming process. Hence a brief and effective method is necessary to satisfy the real-time testing. In this paper, mathematical solutions for errors were deduced from the difference of intensity patterns. Based on the diversity of error distributions, an effective method for distinguishing and diagnosing the error sources is proposed and verified by an elaborative designed simulation. In the actual comparison experiment, vibration, phase-shift error and intensity fluctuation were imposed to demonstrate this method. The results showed that this method can be applied into the real-time measurement and provide an in situ diagnosing technique.

  10. [Quantification and monitoring of vascular resistance in the lower limbs by the Doppler method (animal model)

    NASA Technical Reports Server (NTRS)

    Arbeille, P.; Berson, M.; Blondeau, B.; Durand, A.; Bodard, S.; Locatelli, A.; Fox, G. E. (Principal Investigator)

    1995-01-01

    The object of this study was to define and validate a non-invasive method of evaluation and monitoring of vascular resistances in the leg. Blood flow velocity was measured by Doppler ultrasound in an animal model (ewe) with similar blood flow characteristics in the lower limb as man and allowing access to the required invasive measurements for validation of the method (pressure and flow). Vascular resistances distal to the measuring point (femoral, for example) were assessed using the resistance index R = D/S, S being the peak systolic deflection and D that of diastolic reflux of the Doppler spectral analysis of flow in the femoral artery. The values and variations of this resistance index were compared with the vascular resistances calculated from measurements of pressure and flow at the point of Doppler sampling and expressed in mmHg/ml/min. Femoral flow was measured by Doppler ultrasound (Doppler-echo), and mean pressure by an arterial catheter introduced into the abdominal aorta. Compression of the lower limb veins induced a venous return resulting in a reduction of cardiac output and femoral flow. During compression, femoral flow decreased by an average of 29% (p < 0.001) although mean pressure and heart rate did not change significantly. The femoral resistance index (Rf) increased by an average of 37.5% (p < 0.01) and vascular resistances increased by 45.9% (p < 0.01). Injection of 1 mg adrenaline induced peripheral vasoconstriction with an increase in blood pressure and a decrease in heart rate and femoral flow.(ABSTRACT TRUNCATED AT 250 WORDS).

  11. Method and system to measure temperature of gases using coherent anti-stokes doppler spectroscopy

    DOEpatents

    Rhodes, Mark

    2013-12-17

    A method of measuring a temperature of a noble gas in a chamber includes providing the noble gas in the chamber. The noble gas is characterized by a pressure and a temperature. The method also includes directing a first laser beam into the chamber and directing a second laser beam into the chamber. The first laser beam is characterized by a first frequency and the second laser beam is characterized by a second frequency. The method further includes converting at least a portion of the first laser beam and the second laser beam into a coherent anti-Stokes beam, measuring a Doppler broadening of the coherent anti-Stokes beam, and computing the temperature using the Doppler broadening.

  12. Performance Of A Doppler-Corrected MDPSK Detector

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien M.; Jedrey, Thomas C.; Hinedi, Sami; Agan, Martin J.

    1994-01-01

    Report presents theoretical analysis of effect of rate of change of Doppler shift of received multiple-differential-phase-shift-keyed (MDPSK) radio signal on performance of Doppler-corrected differential detector. In particular detector, phase of received signal corrected for Doppler shift by use of Doppler estimator designed to operate in presence of negligibly small Doppler rate.

  13. Imaging shear wave propagation for elastic measurement using OCT Doppler variance method

    NASA Astrophysics Data System (ADS)

    Zhu, Jiang; Miao, Yusi; Qu, Yueqiao; Ma, Teng; Li, Rui; Du, Yongzhao; Huang, Shenghai; Shung, K. Kirk; Zhou, Qifa; Chen, Zhongping

    2016-03-01

    In this study, we have developed an acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE) method for the visualization of the shear wave and the calculation of the shear modulus based on the OCT Doppler variance method. The vibration perpendicular to the OCT detection direction is induced by the remote acoustic radiation force (ARF) and the shear wave propagating along the OCT beam is visualized by the OCT M-scan. The homogeneous agar phantom and two-layer agar phantom are measured using the ARFOE-OCE system. The results show that the ARFOE-OCE system has the ability to measure the shear modulus beyond the OCT imaging depth. The OCT Doppler variance method, instead of the OCT Doppler phase method, is used for vibration detection without the need of high phase stability and phase wrapping correction. An M-scan instead of the B-scan for the visualization of the shear wave also simplifies the data processing.

  14. Earth gravity model improvement - An alternative method for Doppler-tracked satellites

    NASA Astrophysics Data System (ADS)

    Lansard, E.; Biancale, R.

    A new method of earth gravity model improvement based on an analytical formulation of Doppler residuals is presented here in prospect of future geodetic and altimetric missions (DORIS< TOPEX/POSEIDON, ERS1). After an intermediate step of orbit improvement, disturbing forces due to gravity field mismodeling are recovered above tracking statins at satellite altitude. Some significant simulation results for Seasat and DORIS are presented.

  15. Enhanced two-frequency phase-shifting method.

    PubMed

    Hyun, Jae-Sang; Zhang, Song

    2016-06-01

    One of the major challenges of employing a two-frequency (or two-wavelength) phase-shifting algorithm for absolute three-dimensional shape measurement is its sensitivity to noise. Therefore, three- or more-frequency phase-shifting algorithms are often used in lieu of a two-frequency phase-shifting algorithm for applications where the noise is severe. This paper proposes a method to use geometric constraints of digital fringe projection system to substantially reduce the noise impact by allowing the use of more than one period of equivalent phase map for temporal phase unwrapping. Experiments successfully verified the enhanced performance of the proposed method without increasing the number of patterns. PMID:27411193

  16. Coronal and transition-region Doppler shifts of an active region 3D-MHD model as indicator for the magnetic activity cycle of solar-like stars

    NASA Astrophysics Data System (ADS)

    Bourdin, Philippe A.

    2015-08-01

    For the Sun and solar-like stars, Doppler blueshifts are observed in the hot corona, while in average redshifts are seen in the cooler transition region layer below the corona. This clearly contradicts the idea of a continuous flow-equilibrium starting from a star's atmosphere and forming the stellar wind. To explain this, we implement a 3D-MHD model of the solar corona above an observed active region and use an atomic database to obtain the emission from the million Kelvin hot plasma. The generated EUV-bright loops system from the model compares well to the observed coronal loops. Therefore, we have access to realistic plasma parameters, including the flow dynamics within the active region core, and can derive total spectra as if we look the Sun as a star. We compare the model spectra to actual statistical observations of the Sun taken at different magnetic activity levels. We find characteristic Doppler-shift statistics that can be used to identify the magnetic activity state of the Sun and solar-like stars. This should help to model the variability of such stars by inferring their activity level from total spectra of coronal and transition-region emission lines.

  17. Doppler shift measurement of Balmer-alpha line spectrum emission from a plasma in a negative hydrogen ion source

    SciTech Connect

    Wada, M. Doi, K.; Kisaki, M.; Nakano, H.; Tsumori, K.; Nishiura, M.

    2015-04-08

    Balmer-α light emission from the extraction region of the LHD one-third ion source has shown a characteristic Doppler broadening in the wavelength spectrum detected by a high resolution spectrometer. The spectrum resembles Gaussian distribution near the wavelength of the intensity peak, while it has an additional component of a broader foot. The measured broadening near the wavelength of the intensity peak corresponds to 0.6 eV hydrogen atom temperature. The spectrum exhibits a larger expansion in the blue wing which becomes smaller when the line of sight is tilted toward the driver region from the original observation axis parallel to the plasma grid. A surface collision simulation model predicts the possibility of hydrogen reflection at the plasma grid surface to form a broad Balmer-α light emission spectrum.

  18. Doppler shift and broadening of H-like and He-like Al lines in imploded arrays on MAGPIE and COBRA pulsers experiments

    NASA Astrophysics Data System (ADS)

    Pikuz, S. A.; Douglass, J. D.; Shelkovenko, T. A.; Hammer, D. A.; Hall, G. N.; Lebedev, S. V.; Bland, S. N.; Bott, S. C.; Chittenden, J. P.

    2006-10-01

    Strong broadening and clearly visible ``red'' and ``blue'' shifts of K-shell spectral lines as a function position along the array axis have been observed in the time-integrated spectra of 8-32 wire Al arrays in experiments on the MAGPIE (1.2 MA, 240 ns risetime) and COBRA (1.1 MA, 100 ns risetime) pulsed-power generators. Spectra were recorded using focusing spectrographs with spherically bent mica crystals (FSSR) in configurations in which the film was positioned out of Rowland circle and the influence of the spatial position on a line position in the spectral direction on the film is not negligible. To separate the spectral and spatial shift of the spectral lines, two wide-band spectrographs with 3 spherically bent crystals each (WB-FSSR) with radius of curvature 182 mm have been used in a mirror-symmetric configuration. The measured Doppler shift of the spectral lines varied along the pinch axis and reached ±0.015 å corresponding to a radial plasma velocity of ±5x10^7 cm/s. This research was sponsored by the NNSA under DOE Cooperative Agreement DE-F03-02NA00057.

  19. Direct and indirect methods for studying the energetics and dynamics of the Auger Doppler effect in femtosecond ultra-fast dissociation

    NASA Astrophysics Data System (ADS)

    Björneholm, O.

    2001-09-01

    Molecules may fragment within a few femtoseconds after core-excitation, a phenomenon known as ultra-fast dissociation. With the aim of providing an understanding of the fundamental phenomenology of the Auger Doppler effect, two methods are presented to study the energetics and dynamics, i.e., the kinetic energy release and the fragment velocities in such processes. The first, direct, method is based on the shifts in kinetic energy of the Auger electrons due to the velocity acquired by the fragment in the ultra-fast dissociation process, i.e., the Auger Doppler effect. The second, indirect, method is based on total-energy arguments in a Born-Haber cycle for excitation, dissociation, and ionization. A combination of the two methods is shown to be able to reproduce experimental spectra well. Based on this, predictions are made for other, yet unstudied, molecular systems. It is also shown that the Auger Doppler effect is not static, but will exhibit dynamic photon energy dependence. The complete energetics of the three-body dissociation of a molecule into an electron, an ion, and a neutral fragment on a time-scale of a few femtoseconds can thus be accounted for.

  20. Cross-frequency Doppler sensitive signal processing

    NASA Astrophysics Data System (ADS)

    Wagstaff, Ronald A.

    2005-04-01

    When there is relative motion between an acoustic source and a receiver, a signal can be Doppler shifted in frequency and enter or leave the processing bins of the conventional signal processor. The amount of the shift is determined by the frequency and the rate of change in the distance between the source and the receiver. This frequency Doppler shifting can cause severe reductions in the processors performance. Special cross-frequency signal processing algorithms have recently been developed to mitigate the effects of Doppler. They do this by using calculation paths that cut across frequency bins in order to follow signals during frequency shifting. Cross-frequency spectral grams of a fast-flying sound source were compared to conventional grams, to evaluate the performance of this new signal processing method. The Doppler shifts in the data ranged up to 70 contiguous frequency bins. The resulting cross-frequency grams showed that three paths provided small to no improvement. Four paths showed improvements for either up-frequency or down-frequency shifting, but not for both. Two paths showed substantial improvement for both up-frequency and down-frequency shifting. The cross-frequency paths will be defined, and comparisons between conventional and cross-frequency grams will be presented. [Work supported by Miltec Corporation.

  1. [Visualization of blood flow in abdominal tumors by the ultrasonic pulsed Doppler method].

    PubMed

    Ueno, N; Yamanaka, T; Kimura, K

    1989-06-01

    The clinical utility of visualizing the blood flow in the margin and inside of tumors by ultrasonic pulsed Doppler method (UPDM) was evaluated in 54 patients (85 lesions) with various abdominal tumors. It was proved that UPDM was able to evaluate the vascularity of the tumor and the surrounding vascular system. These results indicate that this method may be applied clinically for judging the effects of and the indications for the transcatheter arterial embolization (TAE) therapy. It is also suggested that UPDM may be applied in the differential diagnosis of tumors according to the changes of blood velocity and wave patterns. PMID:2677449

  2. Laser-Doppler flowmetry--a non-invasive and continuous method for blood flow evaluation in microvascular studies.

    PubMed

    Oberg, P A; Tenland, T; Nilsson, G E

    1984-01-01

    Skin viability has during the last decades been studied by a number of different techniques. Some of these are briefly presented in this paper. One method, based on the laser-Doppler principle, makes possible continuous and noninvasive measurement of blood flow in the outermost layer (1 mm) of the skin. The basic physical principles and the properties of this flowmeter are presented. Some clinical and research applications of laser-Doppler flowmetry in a number of medical disciplines are discussed. PMID:6236674

  3. The ionospheric response to disturbances initiated by an industrial explosion - The Doppler method

    NASA Astrophysics Data System (ADS)

    Alebastrov, V. A.; Bezruchko, L. I.; Belenkii, M. I.; Borisov, B. B.; Drobzhev, V. I.

    An analysis of data obtained using the Doppler method during vertical, oblique, and back-oblique ionospheric sounding revealed the influence that ground-based explosions with a power of the order of several thousand tons of TNT have on the earth's ionosphere. Three types of surface-explosion generated disturbances propagating at epicentric distances approaching 3000 km at velocities of 1000, 300, and 100 m/s are found. The oblique sounding sonograms show additional signal tracks produced by radiowave scattering at the front of the shock disturbance entering the ionospheric E-region.

  4. Device and method for noresonantly Raman shifting ultraviolet radiation

    DOEpatents

    Loree, Thomas R.; Barker, Dean L.

    1979-01-01

    A device and method for nonresonantly Raman shifting broad band uv excimer laser radiation, which enhances preselected Stokes signals by varying the pressure of the Raman scattering medium, the focal interaction length of the incident radiation within the Raman scattering medium and its power density level. Gaseous molecular H.sub.2, D.sub.2, CH.sub.4 (methane), HD and mixes thereof, and liquid N.sub.2 are used as the Raman scattering medium to frequency shift the outputs of high power KrF and ArF lasers. A cable fed discharge with an unstable resonant cavity configuration is utilized to produce the output laser power levels required for operation.

  5. New method of laser doppler flowmetry signal processing in pulp vitality evaluation after teeth cosmetic treatment

    NASA Astrophysics Data System (ADS)

    Todea, Carmen; Sarpe, Amalia; Vitez, Bogdan; Draganescu, Gheorghe

    2014-01-01

    The present study aims to assess the pulp vitality before and after different tooth bleaching procedures, in order to determine the changes in pulpal microcirculation and whether they are reversible or not. Twelve volunteers were included in this study. For each volunteer, the pulpal blood flow of maxillary teeth was assessed prior to treatment using Laser Doppler Flowmetry. The "in office" bleaching technique was used 6 anterior teeth, with two different gels, a conventional one chemically activated (Group I 3teeth) and another one activated using Nd:YAG laser (Group II-3 teeth). The bleaching agents were applied on counterpart teeth and, after obtaining a esthetic results for each tooth, the pulpal blood flow was assessed using Laser Doppler Flowmetry immediately after treatment and then after one day and one week. All data were collected and statistically analyzed. Immediately after treatment, the assessment showed an increase of pulpal blood flow, for both study groups, but higher in Group I as compared to Group II (p<0.005). The subsequent assessments showed a reduction of the pulpal blood flow with non - significant differences between the study groups (p<0.005).The results suggest that the tooth bleaching procedurere presents a safe treatment method, which does not lead to irreversible damage to the dental pulp, when used correctly.

  6. Doppler-shift compensation in the Taiwanese leaf-nosed bat (Hipposideros terasensis) recorded with a telemetry microphone system during flight.

    PubMed

    Hiryu, Shizuko; Katsura, Koji; Lin, Liang-Kong; Riquimaroux, Hiroshi; Watanabe, Yoshiaki

    2005-12-01

    Biosonar behavior was examined in Taiwanese leaf-nosed bats (Hipposideros terasensis; CF-FM bats) during flight. Echolocation sounds were recorded using a telemetry microphone mounted on the bat's head. Flight speed and three-dimensional trajectory of the bat were reconstructed from images taken with a dual high-speed video camera system. Bats were observed to change the intensity and emission rate of pulses depending on the distance from the landing site. Frequencies of the dominant second harmonic constant frequency component (CF2) of calls estimated from the bats' flight speed agreed strongly with observed values. Taiwanese leaf-nosed bats changed CF2 frequencies depending on flight speed, which caused the CF2 frequencies of the Doppler-shifted echoes to remain constant. Pulse frequencies were also estimated using echoes returning directly ahead of the bat and from its sides for two different flight conditions: landing and U-turn. Bats in flight may periodically alter their attended angles from the front to the side when emitting echolocation pulses. PMID:16419835

  7. Doppler-shift compensation in the Taiwanese leaf-nosed bat (Hipposideros terasensis) recorded with a telemetry microphone system during flight

    NASA Astrophysics Data System (ADS)

    Hiryu, Shizuko; Katsura, Koji; Lin, Liang-Kong; Riquimaroux, Hiroshi; Watanabe, Yoshiaki

    2005-12-01

    Biosonar behavior was examined in Taiwanese leaf-nosed bats (Hipposideros terasensis; CF-FM bats) during flight. Echolocation sounds were recorded using a telemetry microphone mounted on the bat's head. Flight speed and three-dimensional trajectory of the bat were reconstructed from images taken with a dual high-speed video camera system. Bats were observed to change the intensity and emission rate of pulses depending on the distance from the landing site. Frequencies of the dominant second harmonic constant frequency component (CF2) of calls estimated from the bats' flight speed agreed strongly with observed values. Taiwanese leaf-nosed bats changed CF2 frequencies depending on flight speed, which caused the CF2 frequencies of the Doppler-shifted echoes to remain constant. Pulse frequencies were also estimated using echoes returning directly ahead of the bat and from its sides for two different flight conditions: landing and U-turn. Bats in flight may periodically alter their attended angles from the front to the side when emitting echolocation pulses.

  8. Laser Doppler method for investigation of blood microcirculation in mucous membrane and tooth pulp

    NASA Astrophysics Data System (ADS)

    Sedykh, Alexey V.; Kharish, Natalia A.; Karpovich, Alexander; Lepilin, Alexander V.; Ulyanov, Sergey S.

    2001-05-01

    The results of statistical analysis of Doppler spectra of scattered intensity, obtained from tissues of oral cavity membrane of healthy volunteers, are presented. The dependence of the spectral moments of Doppler signal on cutoff frequency is investigated. Some physiological tests in combination with LDF technique are suggested as a new diagnostic tool. In addition, the results of statistical analysis of Doppler spectra, obtained from tooth pulp of patients, are presented.

  9. Variable Doppler shifts of the thermal wind absorption lines in low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Madej, O. K.; Jonker, P. G.; Díaz Trigo, M.; Miškovičová, I.

    2014-02-01

    In this paper, we address the general applicability of the method pioneered by Zhang, Liao & Yao in which the motion of the compact object can be tracked using wind X-ray absorption lines. We present the velocity measurements of the thermal wind lines observed in the X-ray spectrum of a few low-mass X-ray binaries: GX 13+1, H 1743-322, GRO J1655-40 and GRS 1915+105. We find that the variability in the velocity of the wind lines in about all of the sources is larger than conceivable radial velocity variations of the compact object. GX 13+1 provides a potential exception, although it would require the red giant star to be massive with a mass of ≈5-6 M⊙. We conclude that the variability of the source luminosity occurring on a time-scale of days/months can affect the outflow properties making it difficult to track the orbital motion of the compact object using current observations. Given the intrinsic variability of the outflows we suggest that low-mass X-ray binaries showing stable coronae instead of an outflow (e.g. 4U 1254-69, MXB 1659-29, 4U 1624-49) could be more suitable targets for tracking the orbital motion of the compact object.

  10. Doppler Lidar (DL) Handbook

    SciTech Connect

    Newsom, RK

    2012-02-13

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

  11. Advanced Doppler tracking experiments

    NASA Technical Reports Server (NTRS)

    Armstrong, J. W.

    1989-01-01

    The Doppler tracking method is currently the only technique available for broadband gravitational wave searches in the approx. 10(exp -4) to 10(exp -1) Hz low frequency band. A brief review is given of the Doppler method, a discussion of the main noise sources, and a review of experience with current spacecraft and the prospects for sensitivity improvements in an advanced Doppler tracking experiment.

  12. A Method for Characteristic Extraction of Ultrasound Doppler Signal with Peak-valley Relationship under Heavy Noise.

    PubMed

    Lin, Zhang; Liu Dong, C; Jiliu, Zhou

    2005-01-01

    This paper proposes a real-time algorithm estimating clinical useful parameters from the maximum frequency curve of ultrasound Doppler spectrum. Traditional methods always apply some pre-calculations to the frequency waveform, for instance, filtering or scaling transformation, which have limitations on real-time features detection and waveform display. In this paper, we propose and maintain a process unit as a section of the waveform with the help of its phase information and the idea of the changeable scaling in the wavelet, to determine the Doppler waveform parameters in real time. From a set of in vivo Doppler waveforms, our proposed algorithm can pick up right parameters even in very noisy environment. PMID:17282933

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

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

  14. Multipoint observations by CUTLASS radar, Doppler and oblique ionospheric sounding methods during a magnetospheric storm

    NASA Astrophysics Data System (ADS)

    Blagoveshchensky, D. V.; Kornienko, V. A.; Lester, M.; Stocker, A. J.; Warrington, E. M.

    Experimental results during a magnetospheric storm on April 28-29, 2001, obtained in course of High-rate SolarMax IGS/GPS campaign are presented. The analysis completed to date has given rise to the following conclusions. (1) During the expansion and recovery phases of a substorm (which formed part of the storm) the width of the Doppler spectrum on two paths, Murmansk - St. Petersburg and London - St. Petersburg, has a maximum and lies within 10 - 30 Hz, whreas under quiet conditions it varied from 1 to 3 Hz. The wide spectrum is associated chiefly with increasing the intensity of ionospheric inhomogeneities during disturbed conditions, although to some extent, the spectral width also depends on the mechanism of propagation on the path. (2) Observations made by the CUTLASS radar located at Hankasalmi, Finland, during the magnetic storm illustrate some of the physical processes in the ionosphere and variations of parameters of its irregularities caused by an impact of geophysical disturbances. The characteristics of the ionospheric irregularities derived from the radar data are consistent with estimations made by the Doppler method. (3) The variations of radio wave propagation parameters observed on OIS data during the storm on high and middle latitude paths (Murmansk- St. Petersburg and Inskip - Leicester) have some similar features which occur when the signal is reflected from the F2-layer. Differences, however, occur for signals reflected from the ionospheric E-layer. (4) The results of these experiments and the derived characteristics could be useful in understanding magnetosphere-ionosphere coupling, in Space Weather problems, and for forecasting the ionospheric state during moderate intensity magnetospheric disturbances.

  15. Imaging and characterizing shear wave and shear modulus under orthogonal acoustic radiation force excitation using OCT Doppler variance method.

    PubMed

    Zhu, Jiang; Qu, Yueqiao; Ma, Teng; Li, Rui; Du, Yongzhao; Huang, Shenghai; Shung, K Kirk; Zhou, Qifa; Chen, Zhongping

    2015-05-01

    We report on a novel acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE) technique for imaging shear wave and quantifying shear modulus under orthogonal acoustic radiation force (ARF) excitation using the optical coherence tomography (OCT) Doppler variance method. The ARF perpendicular to the OCT beam is produced by a remote ultrasonic transducer. A shear wave induced by ARF excitation propagates parallel to the OCT beam. The OCT Doppler variance method, which is sensitive to the transverse vibration, is used to measure the ARF-induced vibration. For analysis of the shear modulus, the Doppler variance method is utilized to visualize shear wave propagation instead of Doppler OCT method, and the propagation velocity of the shear wave is measured at different depths of one location with the M scan. In order to quantify shear modulus beyond the OCT imaging depth, we move ARF to a deeper layer at a known step and measure the time delay of the shear wave propagating to the same OCT imaging depth. We also quantitatively map the shear modulus of a cross-section in a tissue-equivalent phantom after employing the B scan. PMID:25927794

  16. Imaging and characterizing shear wave and shear modulus under orthogonal acoustic radiation force excitation using OCT Doppler variance method

    PubMed Central

    Zhu, Jiang; Qu, Yueqiao; Ma, Teng; Li, Rui; Du, Yongzhao; Huang, Shenghai; Shung, K. Kirk; Zhou, Qifa; Chen, Zhongping

    2015-01-01

    We report on a novel acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE) technique for imaging shear wave and quantifying shear modulus under orthogonal acoustic radiation force (ARF) excitation using the optical coherence tomography (OCT) Doppler variance method. The ARF perpendicular to the OCT beam is produced by a remote ultrasonic transducer. A shear wave induced by ARF excitation propagates parallel to the OCT beam. The OCT Doppler variance method, which is sensitive to the transverse vibration, is used to measure the ARF-induced vibration. For analysis of the shear modulus, the Doppler variance method is utilized to visualize shear wave propagation instead of Doppler OCT method, and the propagation velocity of the shear wave is measured at different depths of one location with the M scan. In order to quantify shear modulus beyond the OCT imaging depth, we move ARF to a deeper layer at a known step and measure the time delay of the shear wave propagating to the same OCT imaging depth. We also quantitatively map the shear modulus of a cross-section in a tissue-equivalent phantom after employing the B scan. PMID:25927794

  17. Fluid Shifts

    NASA Technical Reports Server (NTRS)

    Stenger, M.; Hargens, A.; Dulchavsky, S.; Ebert, D.; Lee, S.; Lauriie, S.; Garcia, K.; Sargsyan, A.; Martin, D.; Ribeiro, L.; Lui, J.; Macias, B.; Arbeille, P.; Danielson, R.; Chang, D.; Johnston, S.; Ploutz-Snyder, R.; Smith, S.

    2016-01-01

    NASA is focusing on long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low-Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but more than 50% of ISS astronauts experienced more profound, chronic changes with objective structural and functional findings such as papilledema and choroidal folds. Globe flattening, optic nerve sheath dilation, and optic nerve tortuosity also are apparent. This pattern is referred to as the visual impairment and intracranial pressure (VIIP) syndrome. VIIP signs and symptoms, as well as postflight lumbar puncture data, suggest that elevated intracranial pressure (ICP) may be associated with the spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight, and to correlate these findings with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as the VIIP-related effects of those shifts, is predicted by the crewmember's preflight conditions and responses to acute hemodynamic manipulations (such as head-down tilt). Lastly, we will evaluate the patterns of fluid distribution in ISS astronauts during acute reversal of fluid shifts through application of lower body negative pressure (LBNP) interventions to characterize and explain general and individual responses. METHODS: We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the Figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, calcaneus tissue thickness (by

  18. On the detection of acoustic-gravity waves generated by typhoon by use of real time HF Doppler frequency shift sounding system

    NASA Astrophysics Data System (ADS)

    Huang, Yinn-Nien; Cheng, Kang; Chen, Sen-Wen

    1985-07-01

    A development of a direct vision type high-frequency Doppler frequency sounder and a setup of HF Doppler frequency sounding array at the northern part of Taiwan Island were presented. By use of all typhoons that occurred in 1982 and 1983, the detectability of the typhoon-generated acoustic-gravity waves by use of this HF Doppler frequency sounding array was presented. The results show that the acoustic-gravity waves generated by a typhoon can be detected by this sounding array; however, the detectability is only 2 out of 12.

  19. A novel INS and Doppler sensors calibration method for long range underwater vehicle navigation.

    PubMed

    Tang, Kanghua; Wang, Jinling; Li, Wanli; Wu, Wenqi

    2013-01-01

    Since the drifts of Inertial Navigation System (INS) solutions are inevitable and also grow over time, a Doppler Velocity Log (DVL) is used to aid the INS to restrain its error growth. Therefore, INS/DVL integration is a common approach for Autonomous Underwater Vehicle (AUV) navigation. The parameters including the scale factor of DVL and misalignments between INS and DVL are key factors which limit the accuracy of the INS/DVL integration. In this paper, a novel parameter calibration method is proposed. An iterative implementation of the method is designed to reduce the error caused by INS initial alignment. Furthermore, a simplified INS/DVL integration scheme is employed. The proposed method is evaluated with both river trial and sea trial data sets. Using 0.03°/h(1σ) ring laser gyroscopes, 5 × 10-5 g(1σ) quartz accelerometers and DVL with accuracy 0.5% V ± 0.5 cm/s, INS/DVL integrated navigation can reach an accuracy of about 1‰ of distance travelled (CEP) in a river trial and 2‰ of distance travelled (CEP) in a sea trial. PMID:24169542

  20. A Novel INS and Doppler Sensors Calibration Method for Long Range Underwater Vehicle Navigation

    PubMed Central

    Tang, Kanghua; Wang, Jinling; Li, Wanli; Wu, Wenqi

    2013-01-01

    Since the drifts of Inertial Navigation System (INS) solutions are inevitable and also grow over time, a Doppler Velocity Log (DVL) is used to aid the INS to restrain its error growth. Therefore, INS/DVL integration is a common approach for Autonomous Underwater Vehicle (AUV) navigation. The parameters including the scale factor of DVL and misalignments between INS and DVL are key factors which limit the accuracy of the INS/DVL integration. In this paper, a novel parameter calibration method is proposed. An iterative implementation of the method is designed to reduce the error caused by INS initial alignment. Furthermore, a simplified INS/DVL integration scheme is employed. The proposed method is evaluated with both river trial and sea trial data sets. Using 0.03°/h(1σ) ring laser gyroscopes, 5 × 10−5 g(1σ) quartz accelerometers and DVL with accuracy 0.5% V ± 0.5 cm/s, INS/DVL integrated navigation can reach an accuracy of about 1‰ of distance travelled (CEP) in a river trial and 2‰ of distance travelled (CEP) in a sea trial. PMID:24169542

  1. Method and apparatus for executing a shift in a hybrid transmission

    DOEpatents

    Gupta, Pinaki; Kaminsky, Lawrence A; Demirovic, Besim

    2013-09-03

    A method for executing a transmission shift in a hybrid transmission including first and second electric machines includes executing a shift-through-neutral sequence from an initial transmission state to a target transmission state including executing an intermediate shift to neutral. Upon detecting a change in an output torque request while executing the shift-through-neutral sequence, possible recovery shift paths are identified. Available ones of the possible recovery shift paths are identified and a shift cost for each said available recovery shift path is evaluated. The available recovery shift path having a minimum shift cost is selected as a preferred recovery shift path and is executed to achieve a non-neutral transmission state.

  2. Advances in Doppler OCT

    PubMed Central

    Liu, Gangjun; Chen, Zhongping

    2014-01-01

    We review the principle and some recent applications of Doppler optical coherence tomography (OCT). The advances of the phase-resolved Doppler OCT method are described. Functional OCT algorithms which are based on an extension of the phase-resolved scheme are also introduced. Recent applications of Doppler OCT for quantification of flow, imaging of microvasculature and vocal fold vibration, and optical coherence elastography are briefly discussed. PMID:24443649

  3. A Pedestrian Detection Scheme Using a Coherent Phase Difference Method Based on 2D Range-Doppler FMCW Radar

    PubMed Central

    Hyun, Eugin; Jin, Young-Seok; Lee, Jong-Hun

    2016-01-01

    For an automotive pedestrian detection radar system, fast-ramp based 2D range-Doppler Frequency Modulated Continuous Wave (FMCW) radar is effective for distinguishing between moving targets and unwanted clutter. However, when a weak moving target such as a pedestrian exists together with strong clutter, the pedestrian may be masked by the side-lobe of the clutter even though they are notably separated in the Doppler dimension. To prevent this problem, one popular solution is the use of a windowing scheme with a weighting function. However, this method leads to a spread spectrum, so the pedestrian with weak signal power and slow Doppler may also be masked by the main-lobe of clutter. With a fast-ramp based FMCW radar, if the target is moving, the complex spectrum of the range- Fast Fourier Transform (FFT) is changed with a constant phase difference over ramps. In contrast, the clutter exhibits constant phase irrespective of the ramps. Based on this fact, in this paper we propose a pedestrian detection for highly cluttered environments using a coherent phase difference method. By detecting the coherent phase difference from the complex spectrum of the range-FFT, we first extract the range profile of the moving pedestrians. Then, through the Doppler FFT, we obtain the 2D range-Doppler map for only the pedestrian. To test the proposed detection scheme, we have developed a real-time data logging system with a 24 GHz FMCW transceiver. In laboratory tests, we verified that the signal processing results from the proposed method were much better than those expected from the conventional 2D FFT-based detection method. PMID:26805835

  4. A Pedestrian Detection Scheme Using a Coherent Phase Difference Method Based on 2D Range-Doppler FMCW Radar.

    PubMed

    Hyun, Eugin; Jin, Young-Seok; Lee, Jong-Hun

    2016-01-01

    For an automotive pedestrian detection radar system, fast-ramp based 2D range-Doppler Frequency Modulated Continuous Wave (FMCW) radar is effective for distinguishing between moving targets and unwanted clutter. However, when a weak moving target such as a pedestrian exists together with strong clutter, the pedestrian may be masked by the side-lobe of the clutter even though they are notably separated in the Doppler dimension. To prevent this problem, one popular solution is the use of a windowing scheme with a weighting function. However, this method leads to a spread spectrum, so the pedestrian with weak signal power and slow Doppler may also be masked by the main-lobe of clutter. With a fast-ramp based FMCW radar, if the target is moving, the complex spectrum of the range- Fast Fourier Transform (FFT) is changed with a constant phase difference over ramps. In contrast, the clutter exhibits constant phase irrespective of the ramps. Based on this fact, in this paper we propose a pedestrian detection for highly cluttered environments using a coherent phase difference method. By detecting the coherent phase difference from the complex spectrum of the range-FFT, we first extract the range profile of the moving pedestrians. Then, through the Doppler FFT, we obtain the 2D range-Doppler map for only the pedestrian. To test the proposed detection scheme, we have developed a real-time data logging system with a 24 GHz FMCW transceiver. In laboratory tests, we verified that the signal processing results from the proposed method were much better than those expected from the conventional 2D FFT-based detection method. PMID:26805835

  5. Implementation and characterization of phase-resolved Doppler optical coherence tomography method for flow velocity measurement

    NASA Astrophysics Data System (ADS)

    Pongchalee, Pornthep; Palawong, Kunakorn; Meemon, Panomsak

    2014-06-01

    In this work, the system implementation and characterization of a Phase-Resolved Doppler Optical Coherence Tomography (PR-DOCT) is presented. The phase-resolved Doppler technique was implemented on a custom built Frequency Domain OCT (FD-OCT) that was recently developed at Suranaree University of Technology. Utilizing Doppler phase changed relation in a complex interference signal caused by moving samples, PR-DOCT can produce visualization and characterization of flow activity such as blood flow in biological samples. Here we report the performance of the implemented PR-DOCT system in term of the Velocity Dynamic Range (VDR), which is defined by the range from the minimum to the maximum detectable axial velocity. The minimum detectable velocity was quantified from a histogram distribution of phase difference between consecutive depth-scan signals when performing Doppler imaging of a stationary mirror. By applying a Gaussian curve fitting to the histogram, the Full Width at Half Maximum (FWHM) of the fitted curve was measured to represent the detectable minimum flow velocity of the system. The maximum detectable velocity was limited by the phase wrapping of the Doppler signal, which is governed by the acquisition speed of the system. We demonstrate the 3D Doppler imaging and velocity measurement of feed flow phantom using 100% milk pumped through a microfluidic chip by using a syringe pump system.

  6. Frequency Shift During Mass Properties Testing Using Compound Pendulum Method

    NASA Technical Reports Server (NTRS)

    Wolfe, David; Regan, Chris

    2012-01-01

    During mass properties testing on the X-48B Blended Wing Body aircraft (The Boeing Company, Chicago, Illinois) at the National Aeronautics and Space Administration Dryden Flight Research Center, Edwards, California, large inertia measurement errors were observed in results from compound pendulum swings when compared to analytical models. By comparing periods of oscillations as measured from an average over the test period versus the period of each oscillation, it was noticed that the frequency of oscillation was shifting significantly throughout the test. This phenomenon was only noticed during compound pendulum swings, and not during bifilar pendulum swings. The frequency shift was only visible upon extensive data analysis of the frequency for each oscillation, and did not appear in averaged frequency data over the test period. Multiple test articles, test techniques, and hardware setups were used in attempts to eliminate or identify the cause of the frequency shift. Plotting the frequency of oscillation revealed a region of minimal shift that corresponded to a larger amplitude range. This region of minimal shift provided the most accurate results compared to a known test article; however, the amplitudes that produce accurate inertia measurements are amplitudes larger than those generally accepted in mass properties testing. This paper examines two case studies of the frequency shift, using mass properties testing performed on a dummy test article, and on the X-48B Blended Wing Body aircraft.

  7. The phase shift method for studying nonlinear acoustics in a soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this paper, a phase shift method for studying nonlinear acoustic behaviors of a soil is described. The method uses a phase-lock-in technique to measure the phase shift caused by increments in the amplitude of an excitation. The measured phase shift as a function of dynamic strain amplitude is use...

  8. Chaotic system for self-synchronizing Doppler measurement.

    PubMed

    Carroll, Thomas L

    2005-03-01

    In a radar system, it is necessary to measure both range and velocity of a target. The movement of the target causes a Doppler shift of the radar signal, and the size of the Doppler shift is used to measure the velocity of the target. In this work, a chaotic drive-response system is simulated that detects a Doppler shift in a chaotic signal. The response system can detect Doppler shifts in more than one signal at a time. PMID:15836263

  9. Multi-wave ultrasonic Doppler method for measuring high flow-rates using staggered pulse intervals

    NASA Astrophysics Data System (ADS)

    Muramatsu, Ei; Murakawa, Hideki; Sugimoto, Katsumi; Asano, Hitoshi; Takenaka, Nobuyuki; Furuichi, Noriyuki

    2016-02-01

    The ultrasonic pulsed Doppler method (UDM) can obtain a velocity profile along the path of an ultrasonic beam. However, the UDM measurement volume is relatively large and it is known that the measurement volume affects the measurement accuracy. In this study, the effect of the measurement volume on velocity and flow rate measurements is analytically and experimentally evaluated. The velocities measured using UDM are considered to be ensemble-averaged values over the measurement volume in order to analyze the velocity error due to the measurement volume, while the flow rates are calculated from the integration of the velocity profile across the pipe. The analytical results show that the channel width, i.e. the spatial resolution along the ultrasonic beam axis, rather than the ultrasonic beam diameter, strongly influences the flow rate measurement. To improve the accuracy of the flow rate, a novel method using a multi-wave ultrasonic transducer consisting of two piezo-electric elements with different basic frequencies is proposed to minimize the size of the measurement volume in the near-wall region of a pipe flow. The velocity profiles in the near-wall region are measured using an 8 MHz sensor with a small diameter, while those far from the transducer are measured using a hollow 2 MHz sensor in the multi-wave transducer. The applicability of the multi-wave transducer was experimentally investigated using the water flow-rate calibration facility at the National Institute of Advanced Industrial Science and Technology (AIST). As a result, the errors in the flow rate were found to be below  -1%, while the multi-wave method is shown to be particularly effective for measuring higher flow rates in a large-diameter pipe.

  10. Method of radial velocities for the estimation of aircraft wake vortex parameters from data measured by coherent Doppler lidar.

    PubMed

    Smalikho, I N; Banakh, V A; Holzäpfel, F; Rahm, S

    2015-09-21

    The method of radial velocities (RV) is applied to estimate aircraft wake vortex parameters from measurements conducted with pulsed coherent Doppler lidar (PCDL). Operations of the Stream Line lidar and the 2-µm PCDL are simulated numerically to analyze the accuracy of the estimated wake vortex parameters with the RV method. The RV method is also used to estimate wake vortex trajectories and circulation from lidar measurements at Tomsk and Munich airports. The method of velocity envelopes and the RV method are compared employing data gathered with the 2-µm PCDL. The domain of applicability of the RV method is determined. PMID:26406749

  11. The Cognitive Doppler.

    ERIC Educational Resources Information Center

    Kozoil, Micah E.

    1989-01-01

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

  12. A Method for the Automatic Detection of Insect Clutter in Doppler-Radar Returns.

    SciTech Connect

    Luke,E.; Kollias, P.; Johnson, K.

    2006-06-12

    The accurate detection and removal of insect clutter from millimeter wavelength cloud radar (MMCR) returns is of high importance to boundary layer cloud research (e.g., Geerts et al., 2005). When only radar Doppler moments are available, it is difficult to produce a reliable screening of insect clutter from cloud returns because their distributions overlap. Hence, screening of MMCR insect clutter has historically involved a laborious manual process of cross-referencing radar moments against measurements from other collocated instruments, such as lidar. Our study looks beyond traditional radar moments to ask whether analysis of recorded Doppler spectra can serve as the basis for reliable, automatic insect clutter screening. We focus on the MMCR operated by the Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program at its Southern Great Plains (SGP) facility in Oklahoma. Here, archiving of full Doppler spectra began in September 2003, and during the warmer months, a pronounced insect presence regularly introduces clutter into boundary layer returns.

  13. A proposed experimental method for interpreting Doppler effect measurements and determining their precision

    NASA Technical Reports Server (NTRS)

    Klann, P. G.

    1973-01-01

    The principal problem in the measurement of the Doppler reactivity effect is separating it from the thermal reactivity effects of the expansion of the heated sample. It is shown in this proposal that the thermal effects of sample expansion can be experimentally determined by making additional measurements with porous samples having the same mass and/or volume as the primary sample. By combining these results with independent measurements of the linear temperature coefficient and the computed temperature dependence of the Doppler coefficient the magnitude of the Doppler coefficient may be extracted from the data. These addiational measurements are also useful to experimentally determine the precision of the reactivity oscillator technique used to measure the reactivity effects of the heated sample.

  14. Color deflectometry for phase retrieval using phase-shifting methods

    NASA Astrophysics Data System (ADS)

    Flores, Jorge L.; Legarda-Saenz, Ricardo; Garcia-Torales, G.

    2015-01-01

    In this paper, we propose a technique based on a color fringe pattern used on deflectometry experiment. The advantages of using color fringe patterns together with phase shifting techniques on deflectometry experiment are presented. An experimental wavefront reconstruction of a progressive lens shows the accuracy and simplicity of these techniques used to process the deflection measurements.

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

    NASA Technical Reports Server (NTRS)

    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.

  16. The Doppler Effect--A New Approach

    ERIC Educational Resources Information Center

    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)

  17. Calculations of NMR chemical shifts with APW-based methods

    NASA Astrophysics Data System (ADS)

    Laskowski, Robert; Blaha, Peter

    2012-01-01

    We present a full potential, all electron augmented plane wave (APW) implementation of first-principles calculations of NMR chemical shifts. In order to obtain the induced current we follow a perturbation approach [Pickard and Mauri, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.63.245101 63, 245101 (2001)] and extended the common APW + local orbital (LO) basis by several LOs at higher energies. The calculated all-electron current is represented in traditional APW manner as Fourier series in the interstitial region and with a spherical harmonics representation inside the nonoverlapping atomic spheres. The current is integrated using a “pseudocharge” technique. The implementation is validated by comparison of the computed chemical shifts with some “exact” results for spherical atoms and for a set of solids and molecules with available published data.

  18. Diagnostic methods for deep vein thrombosis: venous Doppler examination, phleborheography, iodine-125 fibrinogen uptake, and phlebography

    SciTech Connect

    Comerota, A.J.; White, J.V.; Katz, M.L.

    1985-10-08

    Since clinical diagnosis of DVT is often inaccurate, it has become accepted that an objective means of diagnosing clot in the deep venous system becomes critically important in the management of these patients. The venous Doppler examination monitors the velocity of blood flowing through a particular vein. Doppler probes in the 5 to 10 mHz range are routinely used. Respiratory variation is a normal finding due to a diminished flow signal during inspiration, followed by a progressive increase in flow signal during expiration. Characteristics of the spontaneous flow signals are the most important part of interpreting the venous Doppler examination. In addition, the response to distal or proximal compression (augmentation) adds important information to the interpretation; however, the response during any augmentation maneuver depends on the rapidity of compression, the force of compression, the quantity of blood in the veins at the time of compression, and the distance between the Doppler probe and the compression point. Phleborheography is a six-channel volumetric plethysmographic technique that monitors volume changes in the lower extremities associated with respiration and foot and calf compression.

  19. Spacecraft Doppler Tracking as a Xylophone Detector

    NASA Technical Reports Server (NTRS)

    Tinto, Massimo

    1996-01-01

    We discuss spacecraft Doppler tracking in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. By using the four-link radio system first proposed by Vessot and Levine, we derive a new method for removing from the combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. Our method provides also for reducing by several orders of magnitude, at selected Fourier components, the frequency fluctuations due to other noise sources, such as the clock on board the spacecraft or the antenna and buffeting of the probe by non-gravitational forces. In this respect spacecraft Doppler tracking can be regarded as a xylophone detector. Estimates of the sensitivities achievable by this xylophone are presented for two tests of Einstein's theory of relativity: searches for gravitational waves and measurements of the gravitational red shift. This experimental technique could be extended to other tests of the theory of relativity, and to radio science experiments that rely on high-precision Doppler measurements.

  20. Doppler Scanning of Sediment Cores: A Useful Method for Studying Sedimentary Structures and Defining the Cutting Angle for Half Cores

    NASA Astrophysics Data System (ADS)

    Acar, Dursun; Cagatay, Namik; Biltekin, Demet; Eris, Kadir; Albut, Gulum; Ogretmen, Nazik; Arslan, Tugce; Sari, Erol

    2014-05-01

    We tested the doppler ultrasound scanning of sediment cores in PVC liners using 8 megahertz ultrasonic waves for detection of angular laminations. The method was tested with artificially prepared cores as well as marine and lake sediment cores, and proven to be a useful and fast technique for imaging and determining the vertical angularity of sedimentary structures, such as laminations and beddings. Random cutting axes provide two angularities on X and Y dimensions. In this study, the main scientific problem is 'sequential angular disconformity'. Importance of detection of these anomalies on whole cores before dividing into half cores based on determining the right cutting axes. Successful imaging was obtained from top three centimeter depth of the sediments below the PVC liner, using a linear Doppler probe. Other Doppler probes (e.g., convex probe) did not work for core scanning because of their wave-form and reflection characteristics. Longitudinal and rotational scanning with gap filler and ultrasonic wave conductive gel material for keeping energy range of wave is necessary for detecting the variation in the dip of the bedding and laminae in the cores before separation. Another angular reasoned problem is about horizontal surface and can be easily solved with adjustable position of sensor or ray source placement. Border of sampling points between two different lithology must be stay with regard to neighbour sediment angles. Vertical angularity correction is not easy and its effect on signal propagation, detection biases and effectible to mixed samples contamination during physical sampling (particle size analyzing). Determining the attitude of angled bedding before core splitting is important for further core analyses such as elemental analysis and digital X-ray radiography. After Doppler scanning, the splitting direction (i.e., vertical to bedding and lamination) can be determined. The method is cheap, quick and non- hazardous to health, unlike the x

  1. A MAGNETIC CALIBRATION OF PHOTOSPHERIC DOPPLER VELOCITIES

    SciTech Connect

    Welsch, Brian T.; Fisher, George H.; Sun, Xudong

    2013-03-10

    The zero point of measured photospheric Doppler shifts is uncertain for at least two reasons: instrumental variations (from, e.g., thermal drifts); and the convective blueshift, a known correlation between intensity and upflows. Accurate knowledge of the zero point is, however, useful for (1) improving estimates of the Poynting flux of magnetic energy across the photosphere, and (2) constraining processes underlying flux cancellation, the mutual apparent loss of magnetic flux in closely spaced, opposite-polarity magnetogram features. We present a method to absolutely calibrate line-of-sight (LOS) velocities in solar active regions (ARs) near disk center using three successive vector magnetograms and one Dopplergram coincident with the central magnetogram. It exploits the fact that Doppler shifts measured along polarity inversion lines (PILs) of the LOS magnetic field determine one component of the velocity perpendicular to the magnetic field, and optimizes consistency between changes in LOS flux near PILs and the transport of transverse magnetic flux by LOS velocities, assuming that ideal electric fields govern the magnetic evolution. Previous calibrations fitted the center-to-limb variation of Doppler velocities, but this approach cannot, by itself, account for residual convective shifts at the limb. We apply our method to vector magnetograms of AR 11158, observed by the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory, and find clear evidence of offsets in the Doppler zero point in the range of 50-550 m s{sup -1}. In addition, we note that a simpler calibration can be determined from an LOS magnetogram and Dopplergram pair from the median Doppler velocity among all near-disk-center PIL pixels. We briefly discuss shortcomings in our initial implementation, and suggest ways to address these. In addition, as a step in our data reduction, we discuss the use of temporal continuity in the transverse magnetic field direction to correct apparently

  2. Research on calibration method of axis-shift multi-camera for aerial photogrammetry

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Fang, Junyong; Ma, Jingyu; Zhang, Xiaohong; Zhao, Dong; Liu, Xue

    2015-12-01

    Axis-shift multi-camera has been gradually applied in the aerial photogrammetry because of its advantages on structure design. In this paper, the basic axis-shift theory is analyzed, and an improved calibration method is described. A prototype system, including two axis-shift cameras, is developed to validate the feasibility and correctness of the proposed method. With the help of a high-precision indoor control field, the parameters of single camera and the relative orientation parameters of the dual camera system are calculated respectively. Experiment result indicates that this calibration method is suitable for the axis-shift multi camera system.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  4. An automated method for analysis and visualization of laser Doppler velocimetry data.

    PubMed

    Healy, T M; Ellis, J T; Fontaine, A A; Jarrett, C A; Yoganathan, A P

    1997-01-01

    The analysis and visualization of large data sets collected by use of laser Doppler velocimetry has presented a challenge to researchers using this technique to investigate complex flow fields. This paper describes an automated procedure for analysis and animation of two- and three-dimensional laser Doppler velocimetry data. The procedure consists of a suite of FORTRAN programs for calculating phase window averages of velocity and the Reynolds stress tensor, calculating the principal normal stresses, maximum shear stresses, and preparation of data files for input into Plot-3D compatible data visualization software. An example application of these techniques to data collected from an in vitro investigation of the retrograde flow field associated with a bileaflet mechanical heart valve is also presented. PMID:9084838

  5. Method and apparatus for optical Doppler tomographic imaging of fluid flow velocity in highly scattering media

    DOEpatents

    Nelson, John Stuart; Milner, Thomas Edward; Chen, Zhongping

    1999-01-01

    Optical Doppler tomography permits imaging of fluid flow velocity in highly scattering media. The tomography system combines Doppler velocimetry with high spatial resolution of partially coherent optical interferometry to measure fluid flow velocity at discrete spatial locations. Noninvasive in vivo imaging of blood flow dynamics and tissue structures with high spatial resolutions of the order of 2 to 10 microns is achieved in biological systems. The backscattered interference signals derived from the interferometer may be analyzed either through power spectrum determination to obtain the position and velocity of each particle in the fluid flow sample at each pixel, or the interference spectral density may be analyzed at each frequency in the spectrum to obtain the positions and velocities of the particles in a cross-section to which the interference spectral density corresponds. The realized resolutions of optical Doppler tomography allows noninvasive in vivo imaging of both blood microcirculation and tissue structure surrounding the vessel which has significance for biomedical research and clinical applications.

  6. Automatic retinal vessel segmentation based on active contours method in Doppler spectral-domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Liu, Wenzhong; Liu, Tan; Song, Wei; Yi, Ji; Zhang, Hao F.

    2013-01-01

    We achieved fast and automatic retinal vessel segmentation by employing the active contours method in Doppler spectral-domain optical coherence tomography (SD-OCT). In a typical OCT B-scan image, we first extracted the phase variations between adjacent A-lines and removed bulk motion. Then we set the initial contour as the boundary of the whole image and iterated until all of the segmented vessel contours became stabilized. Using a typical office computer, the whole segmentation took no more than 50 s, making real-time retinal vessel segmentation possible. We tested the active contours method segmentation in both controlled phantom and in vivo rodent eye images.

  7. Necessary conditions for a maximum likelihood estimate to become asymptotically unbiased and attain the Cramer-Rao lower bound. Part I. General approach with an application to time-delay and Doppler shift estimation.

    PubMed

    Naftali, E; Makris, N C

    2001-10-01

    Analytic expressions for the first order bias and second order covariance of a general maximum likelihood estimate (MLE) are presented. These expressions are used to determine general analytic conditions on sample size, or signal-to-noise ratio (SNR), that are necessary for a MLE to become asymptotically unbiased and attain minimum variance as expressed by the Cramer-Rao lower bound (CRLB). The expressions are then evaluated for multivariate Gaussian data. The results can be used to determine asymptotic biases. variances, and conditions for estimator optimality in a wide range of inverse problems encountered in ocean acoustics and many other disciplines. The results are then applied to rigorously determine conditions on SNR necessary for the MLE to become unbiased and attain minimum variance in the classical active sonar and radar time-delay and Doppler-shift estimation problems. The time-delay MLE is the time lag at the peak value of a matched filter output. It is shown that the matched filter estimate attains the CRLB for the signal's position when the SNR is much larger than the kurtosis of the expected signal's energy spectrum. The Doppler-shift MLE exhibits dual behavior for narrow band analytic signals. In a companion paper, the general theory presented here is applied to the problem of estimating the range and depth of an acoustic source submerged in an ocean waveguide. PMID:11681372

  8. Two new design methods for lithography mask: phase-shifting scattering bar and interlaced phase-shifting mask

    NASA Astrophysics Data System (ADS)

    Yeh, Kwei-Tin; Huang, Chao-Yi

    2014-07-01

    For 193 nm immersion lithography, it is hard to print clear 4X nm dense images (ex. contact holes) on wafer without any modifications due to lower light intensity. In the past, the most common method is to add the scattering bars, which can enhance the light intensity of contact holes. However, with tinier pattern, the distance between scattering bars and contact holes will get quite close. Hence, the error tolerance for mask making was reduced. On the other hand, this method may also cause the pattern twist which will induce pattern crosslink. To solve this issue, a new design method for lithography mask was proposed, which is named "Phase-shifting Scattering Bar", and it shows better performance in 1D chain array patterns than those with traditional scattering bars. However, for even tinier patterns, it is quite difficult to put these scattering bars on mask. Hence, another special design named "Interlaced Phase-shifting Mask" was proposed to handle such tiny dense patterns. In this design, main patterns are also the scattering bars for adjacent patterns. Hence, there is no need for additional tiny scattering bars, and the mask making requirement can be also relaxed. Both of these two mask design are useful tools to trim and modify light intensity profile on wafer. The image contrast was largely enhanced which means a better resolution and a larger process window can be gained without the cost of new illumination equipments.

  9. A data efficient method for characterization of chameleon tongue motion using Doppler radar.

    PubMed

    Singh, Aditya; Hafner, Noah; Lubecke, Victor; Butler, Marguerite

    2012-01-01

    A new technique is described for study of the study of high velocity animal movements using a continuous wave Doppler radar operating at 24 GHz. The movement studied was tongue projection kinematics during prey capture by the lizard Chamaeleo Jacksonii. The measurements were verified with a high speed video reference, recorded at 1000 frames per second. The limitations and advantages of both the methodologies are compared and tongue speeds of 3:65 m/s were observed. These results show a useful application of radar to augment visual sensing of biological motion and enable the use of monitoring in a wider range of situations. PMID:23365957

  10. Theoretical analysis and experimental verification on optical rotational Doppler effect.

    PubMed

    Zhou, Hailong; Fu, Dongzhi; Dong, Jianji; Zhang, Pei; Zhang, Xinliang

    2016-05-01

    We present a theoretical model to sufficiently investigate the optical rotational Doppler effect based on 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 difference of mode index between input and output orbital angular momentum (OAM) light, and linear to the rotating speed of spinning object as well. An experiment is carried out to verify the theoretical model. We explicitly suggest that the spatial spiral phase distribution of spinning object determines the frequency content. The theoretical model makes us better understand the physical processes of rotational Doppler effect, and thus has many related application fields, such as detection of rotating bodies, imaging of surface and measurement of OAM light. PMID:27137615

  11. Theoretical analysis and experimental verification on optical rotational Doppler effect

    NASA Astrophysics Data System (ADS)

    Zhou, Hailong; Fu, Dongzhi; Dong, Jianji; Zhang, Pei; Zhang, Xinliang

    2016-05-01

    We present a theoretical model to sufficiently investigate the optical rotational Doppler effect based on 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 difference of mode index between input and output orbital angular momentum (OAM) light, and linear to the rotating speed of spinning object as well. An experiment is carried out to verify the theoretical model. We explicitly suggest that the spatial spiral phase distribution of spinning object determines the frequency content. The theoretical model makes us better understand the physical processes of rotational Doppler effect, and thus has many related application fields, such as detection of rotating bodies, imaging of surface and measurement of OAM light.

  12. Modified hyper-Ramsey methods for the elimination of probe shifts in optical clocks

    NASA Astrophysics Data System (ADS)

    Hobson, R.; Bowden, W.; King, S. A.; Baird, P. E. G.; Hill, I. R.; Gill, P.

    2016-01-01

    We develop a method of modified hyper-Ramsey spectroscopy in optical clocks, achieving complete immunity to the frequency shifts induced by the probing fields themselves. Using particular pulse sequences with tailored phases, frequencies, and durations, we can derive an error signal centered exactly at the unperturbed atomic resonance with a steep discriminant which is robust against variations in the probe shift. We experimentally investigate the scheme using the magnetically induced 1S0-3P0 transition in 88Sr, demonstrating automatic suppression of a sizable 2 ×10-13 probe Stark shift to below 1 ×10-16 even with very large errors in shift compensation.

  13. Doppler echocardiography

    SciTech Connect

    Labovitz, A.J.; Williams, G.A.

    1988-01-01

    The authors are successful in presenting a basic book on clinical quantitative Doppler echocardiography. It is not intended to be a comprehensive text, but it does cover clinical applications in a succinct fashion. Only the more common diseases in the adult are considered. The subjects are presented logically and are easy to comprehend. The illustrations are good, and the book is paperbound. The basic principles of Doppler echocardiography are presented briefly. The book ends with chapters on left ventricular function (stroke volume and cardiac output), congenital heart disease, and color Doppler echo-cardiography. There are numerous references and a good glossary and index.

  14. Modified shifted angular spectrum method for numerical propagation at reduced spatial sampling rates.

    PubMed

    Ritter, André

    2014-10-20

    The shifted angular spectrum method allows a reduction of the number of samples required for numerical off-axis propagation of scalar wave fields. In this work, a modification of the shifted angular spectrum method is presented. It allows a further reduction of the spatial sampling rate for certain wave fields. We calculate the benefit of this method for spherical waves. Additionally, a working implementation is presented showing the example of a spherical wave propagating through a circular aperture. PMID:25401659

  15. Transverse flowmetry of carbon particles based on photoacoustic Doppler standard deviation using an auto-correlation method

    NASA Astrophysics Data System (ADS)

    Lu, Tao; Sun, Li-jun

    2015-05-01

    In order to measure the flow velocity of carbon particle suspension perpendicular to the receiving axis of ultrasound transducer, the standard deviation of photoacoustic Doppler frequency spectrum is used to estimate the bandwidth broadening, and the spectrum standard deviation is calculated by an auto-correlation method. A 532 nm pulsed laser with the repetition rate of 20 Hz is used as a pumping source to generate photoacoustic signal. The photoacoustic signals are detected using a focused PZT ultrasound transducer with the central frequency of 10 MHz. The suspension of carbon particles is driven by a syringe pump. The complex photoacoustic signal is calculated by Hilbert transformation from time domain signal before auto-correlation. The standard deviation of the Doppler bandwidth broadening is calculated by averaging the auto-correlation results of several individual A scans. The feasibility of the proposed method is demonstrated by measuring the spectrum standard deviation of the transversal carbon particle flow from 5.0 mm/s to 8.4 mm/s. The experimental results show that the auto-correlation result is approximately linearly distributed within the measuring range.

  16. Cross-correlation Doppler global velocimetry (CC-DGV)

    NASA Astrophysics Data System (ADS)

    Cadel, Daniel R.; Lowe, K. Todd

    2015-08-01

    A flow velocimetry method, cross-correlation Doppler global velocimetry (CC-DGV), is presented as a robust, simplified, and high dynamic range implementation of the Doppler global/planar Doppler velocimetry technique. A sweep of several gigahertz of the vapor absorption spectrum is used for each velocity sample, with signals acquired from both Doppler-shifted scattered light within the flow and a non-Doppler shifted reference beam. Cross-correlation of these signals yields the Doppler shift between them, averaged over the duration of the scan. With presently available equipment, velocities from 0 ms-1 to over 3000 ms-1 can notionally be measured simultaneously, making the technique ideal for high speed flows. The processing routine is shown to be robust against large changes in the vapor pressure of the iodine cell, benefiting performance of the system in facilities where ambient conditions cannot be easily regulated. Validation of the system was performed with measurements of a model wind turbine blade boundary layer made in a 1.83 m by 1.83 m subsonic wind tunnel for which laser Doppler velocimetry (LDV) measurements were acquired alongside the CC-DGV results. CC-DGV uncertainties of ±1.30 ms-1, ±0.64 ms-1, and ±1.11 ms-1 were determined for the orthogonal stream-wise, transverse-horizontal, and transverse-vertical velocity components, and root-mean-square deviations of 2.77 ms-1 and 1.34 ms-1 from the LDV validation results were observed for Reynolds numbers of 1.5 million and 2 million, respectively. Volumetric mean velocity measurements are also presented for a supersonic jet, with velocity uncertainties of ±4.48 ms-1, ±16.93 ms-1, and ±0.50 ms-1 for the orthogonal components, and self-validation done by collapsing the data with a physical scaling.

  17. Doppler tracking of planetary spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.

    1992-01-01

    This article concerns the measurement of Doppler shift on microwave links that connect planetary spacecraft with the Deep Space Network. Such measurements are made by tracking the Doppler effect with phase-locked loop receivers. A description of equipment and techniques as well as a summary of the appropriate mathematical models are given. The two-way Doppler shift is measured by transmitting a highly-stable microwave (uplink) carrier from a ground station, having the spacecraft coherently transpond this carrier, and using a phase-locked loop receiver at the ground station to track the returned (downlink) carrier. The largest sources of measurement error are usually plasma noise and thermal noise. The plasma noise, which may originate in the ionosphere or the solar corona, is discussed; and a technique to partially calibrate its effect, involving the use of two simultaneous downlink carriers that are coherently related, is described. Range measurements employing Doppler rate-aiding are also described.

  18. Superharmonic microbubble Doppler effect in ultrasound therapy.

    PubMed

    Pouliopoulos, Antonios N; Choi, James J

    2016-08-21

    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  ×  10(4)-5  ×  10(7) 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

  19. Superharmonic microbubble Doppler effect in ultrasound therapy

    NASA Astrophysics Data System (ADS)

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

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

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

  1. Lifetimes in neutron-rich Nd isotopes measured by Doppler profile method

    SciTech Connect

    Ahmad, I.; Lister, C.J.; Morss, L.R.

    1995-08-01

    Lifetimes of the rotational levels in neutron-rich even-even Nd isotopes were deduced from the analysis of the Doppler broadened line shapes. The experiment was performed at Daresbury with the Eurogam array, which at that time consisted of 45 Compton-suppressed Ge detectors and 5 Low-Energy Photon Spectrometers. The source was in the form of a 7-mm pellet which was prepared by mixing 5-mg; {sup 248}Cm and 65-mg KCl and pressing it under high pressure. Events for which three or more detectors fired were used to construct a cubic data array whose axes represented the {gamma}-ray energies and the contents of each channel the number of events with that particular combination of {gamma}-ray energies. From this cubic array, one-dimensional spectra were generated by placing gates on peaks on the other two axes. Gamma-ray spectra of even-even Nd isotopes were obtained by gating on the transitions in the complimentary Kr fragments. The gamma peaks de-exciting states with I {>=} 12 h were found to be broader than the instrumental line width due to the Doppler effect. The line shapes of they-ray peaks were fitted separately with a simple model for the feeding of the states and assuming a rotational band with constant intrinsic quadruple moment and these are shown in Fig. I-27. The quadrupole moments thus determined were found to be in good agreement with the quadrupole moments measured previously for lower spin states. Because of the success of this technique for the Nd isotopes, we intend to apply this technique to the new larger data set collected with the Eurogam II array. The results of this study were published.

  2. Mid-altitude wind measurements with mobile Rayleigh Doppler lidar incorporating system-level optical frequency control method.

    PubMed

    Xia, Haiyun; Dou, Xiankang; Sun, Dongsong; Shu, Zhifeng; Xue, Xianghui; Han, Yan; Hu, Dongdong; Han, Yuli; Cheng, Tingdi

    2012-07-01

    A mobile Rayleigh Doppler lidar based on double-edge technique is developed for mid-altitude wind observation. To reduce the systematic error, a system-level optical frequency control method is proposed and demonstrated. The emission of the seed laser at 1064 nm is used to synchronize the FPI in the optical frequency domain. A servo loop stabilizing the frequency of the seed laser is formed by measuring the absolute frequency of the second harmonic against an iodine absorption line. And, the third harmonic is used for Rayleigh lidar detection. The frequency stability is 1.6 MHz at 1064 nm over 2 minutes. A locking accuracy of 0.3 MHz at 1064 nm is realized. In comparison experiments, wind profiles from the lidar, radiosonde and European Center for Medium range Weather Forecast (ECMWF) analysis show good agreement from 8 km to 25 km. Wind observation over two months is carried out in Urumqi (42.1°N, 87.1°E), northwest of China, demonstrating the stability and robustness of the system. For the first time, quasi-zero wind layer and dynamic evolution of high-altitude tropospheric jet are observed based on Rayleigh Doppler lidar in Asia. PMID:22772226

  3. Photoacoustic Doppler Effect from Flowing Small Light-Absorbing Particles

    NASA Astrophysics Data System (ADS)

    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.

  4. Doppler optical coherence tomography of retinal circulation.

    PubMed

    Tan, Ou; Wang, Yimin; Konduru, Ranjith K; Zhang, Xinbo; Sadda, SriniVas R; Huang, David

    2012-01-01

    Noncontact retinal blood flow measurements are performed with a Fourier domain optical coherence tomography (OCT) system using a circumpapillary double circular scan (CDCS) that scans around the optic nerve head at 3.40 mm and 3.75 mm diameters. The double concentric circles are performed 6 times consecutively over 2 sec. The CDCS scan is saved with Doppler shift information from which flow can be calculated. The standard clinical protocol calls for 3 CDCS scans made with the OCT beam passing through the superonasal edge of the pupil and 3 CDCS scan through the inferonal pupil. This double-angle protocol ensures that acceptable Doppler angle is obtained on each retinal branch vessel in at least 1 scan. The CDCS scan data, a 3-dimensional volumetric OCT scan of the optic disc scan, and a color photograph of the optic disc are used together to obtain retinal blood flow measurement on an eye. We have developed a blood flow measurement software called "Doppler optical coherence tomography of retinal circulation" (DOCTORC). This semi-automated software is used to measure total retinal blood flow, vessel cross section area, and average blood velocity. The flow of each vessel is calculated from the Doppler shift in the vessel cross-sectional area and the Doppler angle between the vessel and the OCT beam. Total retinal blood flow measurement is summed from the veins around the optic disc. The results obtained at our Doppler OCT reading center showed good reproducibility between graders and methods (<10%). Total retinal blood flow could be useful in the management of glaucoma, other retinal diseases, and retinal diseases. In glaucoma patients, OCT retinal blood flow measurement was highly correlated with visual field loss (R(2)>0.57 with visual field pattern deviation). Doppler OCT is a new method to perform rapid, noncontact, and repeatable measurement of total retinal blood flow using widely available Fourier-domain OCT instrumentation. This new technology may improve the

  5. A new adaptive exponential smoothing method for non-stationary time series with level shifts

    NASA Astrophysics Data System (ADS)

    Monfared, Mohammad Ali Saniee; Ghandali, Razieh; Esmaeili, Maryam

    2014-07-01

    Simple exponential smoothing (SES) methods are the most commonly used methods in forecasting and time series analysis. However, they are generally insensitive to non-stationary structural events such as level shifts, ramp shifts, and spikes or impulses. Similar to that of outliers in stationary time series, these non-stationary events will lead to increased level of errors in the forecasting process. This paper generalizes the SES method into a new adaptive method called revised simple exponential smoothing (RSES), as an alternative method to recognize non-stationary level shifts in the time series. We show that the new method improves the accuracy of the forecasting process. This is done by controlling the number of observations and the smoothing parameter in an adaptive approach, and in accordance with the laws of statistical control limits and the Bayes rule of conditioning. We use a numerical example to show how the new RSES method outperforms its traditional counterpart, SES.

  6. Effect of beam broadening on the VHF Doppler mini-radar simple method for correcting wind velocity errors

    NASA Astrophysics Data System (ADS)

    Candusso, J.-P.; Crochet, M.

    2001-01-01

    A Doppler VHF mini-radar has been developed at LSEET (Laboratoire de Sondages de l'Environnement Terrestre) to permit investigations at low altitudes, where classical large ST-VHF profilers are blind in the first kilometers of the atmosphere, and UHF boundary layer radars are disturbed by precipitations, birds and insects echoes. Due to a small size of the antenna array, beam broadening effects are important and can provide errors in the atmospheric parameter estimation (reflectivity and wind velocity). A simple overlapping correction method based on the decomposition of the power spectrum is employed to retrieve wind velocity profiles. Measurements from a high-resolution ST radar are used as a benchmark which allows data comparisons and evaluation of this new method.

  7. [A method for resolving spectra shift in the urban air quality monitoring system (DOAS)].

    PubMed

    Liu, Shi-Sheng; Wei, Qing-Nong; Feng, Wei-Wei; Zhan, Kai; Wang, Feng-Ping

    2009-06-01

    In the urban air quality monitoring system, there is spectra shift which is caused by environment factors on the optical part (temperature and optic fiber position), or by the self-change of Xe-lamp. Relative spectra shift will occur if the shift of lamp-spectrum and air-spectrum is inconsistent which has direct influences on the accuracy of the measurement results. So the match of wavelength between lamp-spectrum and air-spectrum should be considered when we retrieve pollutants concentration measurement of trace gas in the atmosphere through DOAS method. Based on the study of the unique structures for Xe-lamp emitting spectrum, a method for the calibration of two signal spectra using Xe-lamp emitting peak and least square fitting is given. The results show that, the impact of spectrum shift can be reduced by this method for retrieving results. PMID:19810506

  8. Ultrasonic position and velocity measurement for a moving object by M-sequence pulse compression using Doppler velocity estimation by spectrum-pattern analysis

    NASA Astrophysics Data System (ADS)

    Ikari, Yohei; Hirata, Shinnosuke; Hachiya, Hiroyuki

    2015-07-01

    Pulse compression using a maximum-length sequence (M-sequence) can improve the signal-to-noise ratio (SNR) of the reflected echo in the pulse-echo method. In the case of a moving object, however, the echo is modulated owing to the Doppler effect. The Doppler-shifted M-sequence-modulated signal cannot be correlated with the reference signal that corresponds to the transmitted M-sequence-modulated signal. Therefore, Doppler velocity estimation by spectrum-pattern analysis of a cyclic M-sequence-modulated signal and cross correlations with Doppler-shifted reference signals that correspond to the estimated Doppler velocities has been proposed. In this paper, measurements of the position and velocity of a moving object by the proposed method are described. First, Doppler velocities of the object are estimated using a microphone array. Secondly, the received signal from each microphone is correlated with each Doppler-shifted reference signal. Then, the position of the object is determined from the B-mode image formed from all cross-correlation functions. After that, the velocity of the object is calculated from velocity components estimated from the Doppler velocities and the position. Finally, the estimated Doppler velocities, determined positions, and calculated velocities are evaluated.

  9. Line shifts in accretion disks—the case of Fe Kα

    NASA Astrophysics Data System (ADS)

    Jovanović, P.; Borka Jovanović, V.; Borka, D.; Popović, L. Č.

    2016-02-01

    Here we present a short overview and main results of our investigations of several effects which can induce shifts in the broad Fe Kα line emitted from relativistic accretion disks around single and binary supermassive black holes. We used numerical simulations based on ray-tracing method in the Kerr metric to study the role of classical Doppler shift, special relativistic transverse Doppler shift and Doppler beaming, general relativistic gravitational redshift, and perturbations of the disk emissivity in the formation of the observed Fe Kα line profiles. Besides, we also investigated whether the observed line profiles from the binary systems of supermassive black holes could be affected by the Doppler shifts due to dynamics of such systems. The presented results demonstrate that all these effects could have a significant influence on the observed profiles of the broad Fe Kα line emitted from relativistic accretion disks around single and binary supermassive black holes.

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

    PubMed

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

    2015-02-01

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

  11. Laser Doppler perfusion imaging: a method for measuring female sexual response.

    PubMed

    Styles, S J; Maclean, A B; Reid, W M N; Sultana, S R

    2006-05-01

    To develop a new noninvasive technique to measure vulval blood flow changes during sexual arousal; 18 healthy volunteers between the age of 20 and 33 years were studied. Each subject underwent two experimental sessions at least 2 weeks apart to coincide with the proliferative and luteal phases of her menstrual cycle. An initial laser Doppler perfusion imaging (LDPI) scan of the vulva was performed. The subject was then given a chapter of erotic fiction to read and a repeat LDPI scan was performed immediately after. The percentage change in flux were calculated: the clitoral skin blood flow increased by 26.4% (P < 0.05), labial skin blood flow by 24.9% (P < 0.05) and the posterior fourchette skin blood flow by 35.3% (P < 0.05). LDPI can detect changes in vulval perfusion during the sexual arousal response and could be used to compare healthy subjects with female sexual dysfunction patients, as well as for assessing the benefits of any treatment for this condition. PMID:16637901

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

    PubMed

    Verrier, Nicolas; Alexandre, Daniel; Gross, Michel

    2014-04-21

    We have extended Laser Doppler holographic microscopy to transmission geometry. The technique is validated with living fish embryos imaged by a modified upright bio-microcope. By varying the frequency of the holographic reference beam, and the combination of frames used to calculate the hologram, multimodal imaging has been performed. Doppler images of the blood vessels for different Doppler shifts, images where the flow direction is coded in RGB colors or movies showing blood cells individual motion have been obtained as well. The ability to select the Fourier space zone that is used to calculate the signal, makes the method quantitative. PMID:24787825

  13. High Resolution Doppler Lidar

    NASA Technical Reports Server (NTRS)

    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.

  14. Application of the loop method for correcting acoustic doppler current profiler discharge measurements biased by sediment transport

    USGS Publications Warehouse

    Mueller, David S.; Wagner, Chad R.

    2006-01-01

    A systematic bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) is attributed to the movement of sediment near the streambed-an issue widely acknowledged by the scientific community. This systematic bias leads to an underestimation of measured velocity and discharge. The integration of a differentially corrected Global Positioning System (DGPS) to track the movement of the ADCP can be used to avoid the systematic bias associated with a moving bed. DGPS systems, however, cannot provide consistently accurate positions because of multipath errors and satellite signal reception problems on waterways with dense tree canopy along the banks, in deep valleys or canyons, and near bridges. An alternative method of correcting for the moving-bed bias was investigated by the U.S. Geological Survey.

  15. Dispersive Extinction Theory of Cosmic Red Shift -- An Alternative to the Big Bang Theory

    NASA Astrophysics Data System (ADS)

    Wang, Ling Jun

    2006-04-01

    A dispersive extinction theory is presented to explain the cosmic red shift and the 2.7 K background radiation as an alternative to the currently prevailing Doppler shift theory and the Big Bang Theory. According to this theory, the cosmic red shift and the 2.7 K background radiation are due to the dispersive scattering and absorption of star light by the space medium. An estimate of the non-linear absorption constant is given by comparing the result to the Hubble constant derived from the observational data. An experimental method is designed to test the validity of the dispersive extinction theory as opposed to the Doppler shift theory. Keywords: red shift, Doppler shift, Big Bang Theory, dispersive extinction theory.

  16. Method for the manufacture of phase shifting masks for EUV lithography

    DOEpatents

    Stearns, Daniel G.; Sweeney, Donald W.; Mirkarimi, Paul B.; Barty, Anton

    2006-04-04

    A method for fabricating an EUV phase shift mask is provided that includes a substrate upon which is deposited a thin film multilayer coating that has a complex-valued reflectance. An absorber layer or a buffer layer is attached onto the thin film multilayer, and the thickness of the thin film multilayer coating is altered to introduce a direct modulation in the complex-valued reflectance to produce phase shifting features.

  17. Over/Undervoltage and undervoltage shift of hybrid islanding detection method of distributed generation.

    PubMed

    Yingram, Manop; Premrudeepreechacharn, Suttichai

    2015-01-01

    The mainly used local islanding detection methods may be classified as active and passive methods. Passive methods do not perturb the system but they have larger nondetection zones, whereas active methods have smaller nondetection zones but they perturb the system. In this paper, a new hybrid method is proposed to solve this problem. An over/undervoltage (passive method) has been used to initiate an undervoltage shift (active method), which changes the undervoltage shift of inverter, when the passive method cannot have a clear discrimination between islanding and other events in the system. Simulation results on MATLAB/SIMULINK show that over/undervoltage and undervoltage shifts of hybrid islanding detection method are very effective because they can determine anti-islanding condition very fast. ΔP/P > 38.41% could determine anti-islanding condition within 0.04 s; ΔP/P < -24.39% could determine anti-islanding condition within 0.04 s; -24.39% ≤ ΔP/P ≤ 38.41% could determine anti-islanding condition within 0.08 s. This method perturbed the system, only in the case of -24.39% ≤ ΔP/P ≤ 38.41% at which the control system of inverter injected a signal of undervoltage shift as necessary to check if the occurrence condition was an islanding condition or not. PMID:25879064

  18. Over/Undervoltage and Undervoltage Shift of Hybrid Islanding Detection Method of Distributed Generation

    PubMed Central

    Premrudeepreechacharn, Suttichai

    2015-01-01

    The mainly used local islanding detection methods may be classified as active and passive methods. Passive methods do not perturb the system but they have larger nondetection zones, whereas active methods have smaller nondetection zones but they perturb the system. In this paper, a new hybrid method is proposed to solve this problem. An over/undervoltage (passive method) has been used to initiate an undervoltage shift (active method), which changes the undervoltage shift of inverter, when the passive method cannot have a clear discrimination between islanding and other events in the system. Simulation results on MATLAB/SIMULINK show that over/undervoltage and undervoltage shifts of hybrid islanding detection method are very effective because they can determine anti-islanding condition very fast. ΔP/P > 38.41% could determine anti-islanding condition within 0.04 s; ΔP/P < −24.39% could determine anti-islanding condition within 0.04 s; −24.39% ≤ ΔP/P ≤ 38.41% could determine anti-islanding condition within 0.08 s. This method perturbed the system, only in the case of −24.39% ≤ ΔP/P ≤ 38.41% at which the control system of inverter injected a signal of undervoltage shift as necessary to check if the occurrence condition was an islanding condition or not. PMID:25879064

  19. Development of Continuous-Energy Eigenvalue Sensitivity Coefficient Calculation Methods in the Shift Monte Carlo Code

    SciTech Connect

    Perfetti, Christopher M; Martin, William R; Rearden, Bradley T; Williams, Mark L

    2012-01-01

    Three methods for calculating continuous-energy eigenvalue sensitivity coefficients were developed and implemented into the SHIFT Monte Carlo code within the Scale code package. The methods were used for several simple test problems and were evaluated in terms of speed, accuracy, efficiency, and memory requirements. A promising new method for calculating eigenvalue sensitivity coefficients, known as the CLUTCH method, was developed and produced accurate sensitivity coefficients with figures of merit that were several orders of magnitude larger than those from existing methods.

  20. Simple method of light-shift suppression in optical pumping systems

    NASA Astrophysics Data System (ADS)

    McGuyer, B. H.; Jau, Y.-Y.; Happer, W.

    2009-06-01

    We report a simple method to suppress the light shift in optical pumping systems. This method uses only frequency modulation of a radio frequency or microwave source, which is used to excite an atomic resonance, to simultaneously lock the source frequency to the atomic resonance and lock the pumping light frequency to suppress the light shift. We experimentally validate the method in a vapor-cell atomic clock and verify the results through numerical simulation. This technique can be applied to many optical pumping systems that experience light shifts. It is especially useful for atomic frequency standards because it improves long-term performance, reduces the influence of the laser, and requires less equipment than previous methods.

  1. [Calculation of spectral shifts of the mutants of bacteriorhodopsin by QM/MM methods].

    PubMed

    Orekhov, F S; Shaĭtan, A K; Shaĭtan, K V

    2012-01-01

    In the present work spectral shifts of adsorption maxima for the number of mutants of bacteriorhodopsin have been calculated using QM/MM hybrid methodology. Along with this calculation an analysis of possible mechanisms of spectral modulation has been performed. Also we have carried out a comparative analysis of modern quantum chemical methods in respect of the level of optical spectra predictability they allow. We have shown that modern hybrid quantum chemical methods reach an acceptable level of preciseness when applied in the calculation of spectral shifts even if the absolute values of adsorption maxima predicted by these methods are underestimated. The number of rules has been found linking the value of spectral shift with the structural rearrangement in the apoprotein. The methods we were using as well as those rules we have found out both may be useful for development of nanoelectronical devices based on mutant species of bacteriorhodopsin (memory elements, optical triggers etc.). PMID:22594277

  2. Doppler characteristics of sea clutter.

    SciTech Connect

    Raynal, Ann Marie; Doerry, Armin Walter

    2010-06-01

    Doppler radars can distinguish targets from clutter if the target's velocity along the radar line of sight is beyond that of the clutter. Some targets of interest may have a Doppler shift similar to that of clutter. The nature of sea clutter is different in the clutter and exo-clutter regions. This behavior requires special consideration regarding where a radar can expect to find sea-clutter returns in Doppler space and what detection algorithms are most appropriate to help mitigate false alarms and increase probability of detection of a target. This paper studies the existing state-of-the-art in the understanding of Doppler characteristics of sea clutter and scattering from the ocean to better understand the design and performance choices of a radar in differentiating targets from clutter under prevailing sea conditions.

  3. A novel method for identifying the order of interference using phase-shifting digital holography.

    PubMed

    Sokkar, T Z N; El-Farahaty, K A; Ramadan, W A; Wahba, H H; Raslan, M I; Hamza, A A

    2016-04-01

    In this paper, we introduced a mathematical method for measuring the optical path length differences (OPDs), which is suitable for large OPD values where the fringes connections are difficult to detect. The proposed method is based on varying the width of the fringes, without changing the wavelength of the used coherent source. Also, in this work, we discussed the need for such method in off-axis phase-shifting digital holography. Low-resolution off-axis holograms failed to detect the correct interference order. In general, off-axis phase-shifting digital holography is limited by the resolution of the captured holograms. The results obtained using our proposed technique were compared to the results obtained using off-axis phase-shifting digital holograms and conventional two-beam interferometry. Holograms were given for illustration. PMID:26588671

  4. Transverse spatial phase-shifting method used in vibration-compensated interferometer

    NASA Astrophysics Data System (ADS)

    Wu, Dong; Zhu, Ri-Hong; Chen, Lei; Li, Jin-Yun

    Based on the conception of temporal phase-shifting interferometry, we have developed a novel technique named transverse spatial phase-shifting method. Only using four photoelectric detectors with a certain spatial array, the method can directly detect wavefront phase variation due to external vibrations. As soon as wavefront variation was determined, some feedback control could be put on interferometer to compensate the vibrations. This method was applied to a Twyman-Green phase-shifting interferometer in which an adaptive vibration-compensated system has been built, it calibrated wavefront phase in real time by a piezoelectric transducer used as both wavefront phase shifter and vibration feedback device, thus fringe pattern could be stabilized and the optical testing would be carried out. Some experimental results were presented.

  5. Improved phase-shifting method for automatic processing of moiré deflectograms.

    PubMed

    Canabal, H; Quiroga, J A; Bernabeu, E

    1998-09-10

    An improved moiré deflectometry phase-shifting technique is presented. A squared grating is used to multiplex the information of the deflections in two orthogonal directions in one image. This procedure avoids the need to rotate the gratings to obtain complete deflection information. However, the use of these gratings makes impossible the application of standard phase-shifting algorithms. Specifically, the problems associated with the nonsinusoidal profile of the moiré fringes and the low-modulation areas produced by the square gratings are solved. A modified moiré deflectometry phase-shifting method is designed to deal with these problems. In addition, a method to obtain the zero order of the prismatic effect is developed. The technique configures a complete and automatic method of mapping ray deflections. From them the refractive power maps can be derived. Experimental results obtained with a progressive-addition lens are shown. PMID:18286121

  6. Visualisation of the oscillation dynamics of cytoplasm in a living cell of Physarum mixomycete plasmodium by the method of optical coherence Doppler tomography

    SciTech Connect

    Bykov, A V; Priezzhev, A V; Lauri, J; Myllylae, Risto

    2009-04-30

    The method of optical coherence Doppler tomography is used for the first time to visualise the oscillatory amoeboid mobility in strands of Physarum polycephalum mixomycete plasmodium and to record periodic radial contractions of the strands and spatiotemporal variations in the velocity of the cytoplasmic flow inside them. (laser biology)

  7. Visualisation of the oscillation dynamics of cytoplasm in a living cell of Physarum mixomycete plasmodium by the method of optical coherence Doppler tomography

    NASA Astrophysics Data System (ADS)

    Bykov, A. V.; Priezzhev, A. V.; Lauri, J.; Myllylä, Risto

    2009-04-01

    The method of optical coherence Doppler tomography is used for the first time to visualise the oscillatory amoeboid mobility in strands of Physarum polycephalum mixomycete plasmodium and to record periodic radial contractions of the strands and spatiotemporal variations in the velocity of the cytoplasmic flow inside them.

  8. Ultrasonic Doppler Modes

    NASA Astrophysics Data System (ADS)

    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.

  9. Method for evaluating chemical shifts of x-ray emission lines in molecules and solids

    NASA Astrophysics Data System (ADS)

    Lomachuk, Yuriy V.; Titov, Anatoly V.

    2013-12-01

    A method of evaluating chemical shifts of x-ray emission lines for period four and heavier elements is developed. This method is based on the relativistic pseudopotential model and one-center restoration approach [Int. J. Quantum Chem.IJQCB20020-760810.1002/qua.20418 104, 223 (2005)] to recover a proper electronic structure in heavy-atom cores after the pseudopotential simulation of chemical compounds. The approximations of instantaneous transition and frozen core are presently applied to derive an expression for chemical shift as a difference between mean values of certain effective operator. The method allows one to avoid evaluation of small quantities (chemical shifts ˜0.01-1 eV) as differences of very large values (transition energies ˜1-100 keV in various compounds). The results of our calculations of chemical shifts for the Kα1, Kα2, and L transitions of group-14 metal cations with respect to neutral atoms are presented. Calculations of Kα1-line chemical shifts for the Pb core transitions in PbO and PbF2 with respect to those in the Pb atom are also performed and discussed. The accuracy of approximations used is estimated and the quality of the calculations is analyzed.

  10. DNA fluorescence shift sensor: a rapid method for the detection of DNA hybridization using silver nanoclusters.

    PubMed

    Lee, Shin Yong; Hairul Bahara, Nur Hidayah; Choong, Yee Siew; Lim, Theam Soon; Tye, Gee Jun

    2014-11-01

    DNA-templated silver nanoclusters (AgNC) are a class of subnanometer sized fluorophores with good photostability and brightness. It has been applied as a diagnostic tool mainly for deoxyribonucleic acid (DNA) detection. Integration of DNA oligomers to generate AgNCs is interesting as varying DNA sequences can result in different fluorescence spectra. This allows a simple fluorescence shifting effect to occur upon DNA hybridization with the hybridization efficiency being a pronominal factor for successful shifting. The ability to shift the fluorescence spectra as a result of hybridization overcomes the issue of background intensities in most fluorescent based assays. Here we describe an optimized method for the detection of single-stranded and double-stranded synthetic forkhead box P3 (FOXP3) target by hybridization with the DNA fluorescence shift sensor. The system forms a three-way junction by successful hybridization of AgNC, G-rich strand (G-rich) to the target DNA, which generated a shift in fluorescence spectra with a marked increase in fluorescence intensity. The DNA fluorescence shift sensor presents a rapid and specific alternative to conventional DNA detection. PMID:25129336

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    BACKGROUND: Doppler tissue echocardiography and color M-mode Doppler flow propagation velocity have proven useful in evaluating cross-sections of patients with left ventricular (LV) dysfunction, but experience with serial changes is limited. Purpose and methods: We tested their use by evaluating the temporal changes of LV function in a pacing-induced congestive heart failure model. Rapid ventricular pacing was initiated and maintained in 20 dogs for 4 weeks. Echocardiography was performed at baseline and weekly during brief pacing cessation. RESULTS: With rapid pacing, LV volume significantly increased and ejection fraction (57%-28%), stroke volume (37-18 mL), and mitral annulus systolic velocity (16.1-6.6 cm/s) by Doppler tissue echocardiography significantly decreased, with ejection fraction and mitral annulus systolic velocity closely correlated (r = 0.706, P <.0001). In contrast to the mitral inflow velocities, mitral annulus early diastolic velocity decreased steadily (12.3-7.3 cm/s) resulting in a dramatic decrease in mitral annulus early/late (1.22-0.57) diastolic velocity with no tendency toward pseudonormalization. The color M-mode Doppler flow propagation velocity also showed significant steady decrease (57-24 cm/s) throughout the pacing period. Multiple regression analysis chose mitral annulus systolic velocity (r = 0.895, P <.0001) and propagation velocity (r = 0.782, P <.0001) for the most important factor predicting LV systolic and diastolic function, respectively. CONCLUSIONS: Doppler tissue echocardiography and color M-mode Doppler flow could evaluate the serial deterioration in LV dysfunction throughout the pacing period. These were more useful in quantifying progressive LV dysfunction than conventional ehocardiographic techniques, and were probably relatively independent of preload. These techniques could be suitable for longitudinal evaluation in addition to the cross-sectional study.

  12. An ultrasonic Doppler venous outflow method for the continuous measurement of cerebral blood flow in conscious sheep.

    PubMed

    Upton, R; Grant, C; Ludbrook, G

    1994-07-01

    A pulsed ultrasonic Doppler venous outflow method was developed for the continuous measurement of global cerebral blood flow (CBF) in conscious sheep. The sheep were prepared under anesthesia with a "suture down"-style ultrasonic flow probe on the dorsal sagittal sinus placed via a trephine hole. Angiographic and dye studies showed that the dorsal sagittal sinus at the point of placement of the probe collected the majority of the blood from the cerebral hemispheres. Studies of the blood velocity profile across the sinus showed that the dimensions of the dorsal sagittal sinus changed minimally with changes in CBF in vivo. The velocity measurements were calibrated under anesthesia against an in vivo direct venous outflow method. Control CBF values for six sheep ranged from 31 to 53 ml/min for the area of brain described above; for two sheep in which the weight of the brain was determined, this gave total CBF values of approximately 34 and 30 ml min-1 100 g-1. The CBF measured varied in the expected manner with changes in the end-tidal CO2 concentration in expired breath and showed transient reductions with the barbiturate thiopentone and transient increases with the opiate alfentanil. It is concluded that the method is simple and accurate. PMID:8014216

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

    NASA Astrophysics Data System (ADS)

    Roulier, Rémy; Humeau, Anne; Flatley, Thomas P.; Abraham, Pierre

    2005-11-01

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

  14. Doppler effect of subluminal and superluminal sources in eight dimensions

    NASA Astrophysics Data System (ADS)

    Chandola, H. C.; Rajput, B. S.

    1984-06-01

    The study of the relativistic Doppler effect of subliminal and superluminal sources has been undertaken in the eight-dimensional space. It has been shown that correct Doppler shifts are obtained in the external spaces of these sources and the conformal correspondence between Doppler effect curves holds in case of approaching and receeding sources but not in the transverse case.

  15. Compensation of CD-SEM image-distortion detected by View-Shift Method

    NASA Astrophysics Data System (ADS)

    Inoue, Osamu; Kawasaki, Takahiro; Kawada, Hiroki

    2012-03-01

    Local-distortion of CD-SEM image can be detected and compensated by a unique technique: View-Shift method. As design rule of semiconductor device is getting shrunk, metrology by critical dimension scanning electron microscope (CD-SEM) is not only for measuring dimension but also shape, such as 2D contour of hot-spot pattern and OPC calibration-pattern. Accuracy of the shape metrology is dependent on the local image-distortion that consists of two components: magnification distortion and shape distortion. The magnification distortion can be measured by pitchcalibration method, that measures pitch of an identical line pattern at a lot of locations in image. However, this method cannot measure the shape distortion, that is for instance, bending of a uniform-width line. To measure accurately and quickly the image-distortion, we invented the View-Shift method, in which images of uniquetexture sample are taken before and after an image-shift by about 100nm. Between the two images we measure displacements of the unique-textures found at each grid-point spread over the image. Variation of the local displacements indicates the local image-distortion. In this work, we demonstrate a method to compensate the image-distortion detected by the View-Shift method. Due to the image-distortion, edge-points determined in SEM-image have already been dislocated. Such dislocation can be relocated to compensate the detected local-distortion. Onsite and on-demand compensation right before CD-SEM measurement for process monitoring is possible because we can quickly apply the View-Shift method and complete the compensation in a few minutes.

  16. Time-resolved flowmetering of gas-liquid two-phase pipe flow by ultrasound pulse Doppler method

    NASA Astrophysics Data System (ADS)

    Murai, Yuichi; Tasaka, Yuji; Takeda, Yasushi

    2012-03-01

    Ultrasound pulse Doppler method is applied for componential volumetric flow rate measurement in multiphase pipe flow consisted of gas and liquid phases. The flowmetering is realized with integration of measured velocity profile over the cross section of the pipe within liquid phase. Spatio-temporal position of interface is detected also with the same ultrasound pulse, which further gives cross sectional void fraction. A series of experimental demonstration was shown by applying this principle of measurement to air-water two-phase flow in a horizontal tube of 40 mm in diameter, of which void fraction ranges from 0 to 90% at superficial velocity from 0 to 15 m/s. The measurement accuracy is verified with a volumetric type flowmeter. We also analyze the accuracy of area integration of liquid velocity distribution for many different patterns of ultrasound measurement lines assigned on the cross section of the tube. The present method is also identified to be pulsation sensor of flow rate that fluctuates with complex gas-liquid interface behavior.

  17. Doppler Wind Measurements of Mars Atmospheric Circulation

    NASA Astrophysics Data System (ADS)

    Clancy, R. T.; Sandor, B. J.; Moriarty-Schieven, G. H.

    2003-05-01

    The late August 2003 opposition of Mars, which occurs very near Mars perihelion, presents its largest angular diameter (25 arcsec) over the previous and subsequent 20 years. Sub-millimeter observations from the James Clerk Maxwell Telescope (JCMT) on August 27 (also scheduled for September 3) will provide 345 Ghz CO line integrations at five beam positions on the Mars disk. Differencing spectral line absorptions observed at east, west, south, and north offset positions from a disk center spectrum yields highly accurate measurements of projected doppler velocities relative to the disk center. As demonstrated in similar Venus mesospheric (90-110 km altitude) wind measurements obtained from JCMT in March 2001 and November 2002 (Clancy et al., 2002), this method provides excellent sensitivity (5 m/sec at 40-80 km altitudes) for short integration periods (10-15 minutes). Systematic uncertainties associated with the absorption lineshape and spectrometer baseline and channel characteristics are minimized, and the steep sub-millimeter line core shapes provide improved doppler shift sensitivity relative to millimeter measurements. Direct wind measurements for the Mars atmosphere are extremely important for validation of Mars general circulation models (GCM, e.g. Forget et al., 1999), yet remain beyond current spacecraft mission capabilities. Lellouch et al. (1993) obtained equinoctial (Ls=200) wind determinations in significant disagreement with Mars GCM predictions, employing 230 Ghz CO doppler line shifts from IRAM. JCMT sub-millimeter CO doppler shifts observed during the August 2003 Mars opposition should be much more accurate, with critical zonal and meridional resolution during the key southern summer season. Atmospheric pressure-temperature profiles (0-75km) will also be retrieved from each disk position 12CO spectrum, complementing the Ls dependence of disk average measurements obtained from previous whole disk JCMT Mars 12CO observations. In addition to doppler

  18. Teaching Doppler Effect with a passing noise source

    NASA Astrophysics Data System (ADS)

    Costa, Ivan F.; Mocellin, Alexandra

    2010-07-01

    The noise pitch variation of a passing noise source allows a low cost experimental approach to calculate speed and, for the first time, distance. We adjusted the recorded noise pitch variation to the Doppler shift equation for sound. We did this by taking into account the frequency delay due to the sound source displacement and performing a Fast Fourier Transform (FFT) of the noise signal using free software. This experimental method was successfully applied to aircraft and automobiles.

  19. A new varied continuation step method in seismic migration by phase shift plus interpolation

    SciTech Connect

    Guotian, T. )

    1992-01-01

    In this paper the principle of wave equation migration using phase shift plus interpolation is described briefly. Wave field extrapolation formula in such migration and final imaging equation are properly modified, with downward extrapolation operator redefined, so that the imaging can be achieved by using fast Fourier transform (FFT). A new varied continuation step method is given which is different from usual one in time domain. The new method, which is different from usual varied continuation step method for time domain interpolation in phase shift plus interpolation migration, uses the downward extrapolation continuation step much longer than a quarter of an apparent wave length; therefore, the efficiency of such seismic migration is improved satisfactorily. The processing results of theoretical model, coal field and high dip seismic data show that this new method is a f-k domain migration technique which is economic and suitable to the seismic data collected from the area where there are high dip formations and complicated geological structures.

  20. Development of continuous-energy eigenvalue sensitivity coefficient calculation methods in the shift Monte Carlo Code

    SciTech Connect

    Perfetti, C.; Martin, W.; Rearden, B.; Williams, M.

    2012-07-01

    Three methods for calculating continuous-energy eigenvalue sensitivity coefficients were developed and implemented into the Shift Monte Carlo code within the SCALE code package. The methods were used for two small-scale test problems and were evaluated in terms of speed, accuracy, efficiency, and memory requirements. A promising new method for calculating eigenvalue sensitivity coefficients, known as the CLUTCH method, was developed and produced accurate sensitivity coefficients with figures of merit that were several orders of magnitude larger than those from existing methods. (authors)

  1. Comparison of Different Methods of Valsalva Maneuver for Right-to-left Shunt Detection by Contrast-Enhanced Transcranial Doppler.

    PubMed

    Guo, Yu-Zhu; Gao, Yong-Sheng; Guo, Zhen-Ni; Niu, Peng-Peng; Yang, Yi; Xing, Ying-Qi

    2016-05-01

    We evaluated 298 patients for right-to-left shunt (RLS) detection by contrast-enhanced transcranial Doppler at rest state (RS), during the conventional Valsalva maneuver (CM), and during the modified Valsalva maneuver (BM: blowing into the connecting tube of a sphygmomanometer at 40 mm Hg for 10 s) in random order, and the degree of RLS along the time of the first microbubble occurrence was recorded. The positive rates were 21.8%, 36.9% and 47.3% for RS, CM and BM, respectively (p < 0.001). BM resulted in a significantly higher positive rate (p = 0.010), and there was a significant difference between the two different methods of VM in terms of the degree of RLS detection (p < 0.001). Further, the first microbubble occurred later during BM than CM (10.22 ± 3.77 s vs. 9.44 ± 4.36 s, p < 0.05). This modified maneuver is an alternative to the conventional one, especially for those who cannot perform the conventional maneuver adequately, but are highly suspected of having RLS. PMID:26928233

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

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

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

  3. Simple Experimental Methods for Determining the Apparent Focal Shift in a Microscope System

    PubMed Central

    Bratton, Benjamin P.; Shaevitz, Joshua W.

    2015-01-01

    Three-dimensional optical microscopy is often complicated by a refractive index mismatch between the sample and objective lens. This mismatch causes focal shift, a difference between sample motion and focal-plane motion, that hinders the accuracy of 3D reconstructions. We present two methods for measuring focal shift using fluorescent beads of different sizes and ring-stained fluorescent beads. These simple methods are applicable to most situations, including total internal reflection objectives and samples very close to the interface. For distances 0–1.5 μm into an aqueous environment, our 1.49-NA objective has a relative focal shift of 0.57 ± 0.02, significantly smaller than the simple n2/n1 approximation of 0.88. We also expand on a previous sub-critical angle theory by means of a simple polynomial extrapolation. We test the validity of this extrapolation by measuring the apparent focal shift in samples where the refractive index is between 1.33 and 1.45 and with objectives with numerical apertures between 1.25 and 1.49. PMID:26270960

  4. Numerical split-shift potential method for relativistic quantum systems with radial symmetry

    NASA Astrophysics Data System (ADS)

    Lv, Q. Z.; Norris, S.; Su, Q.; Grobe, R.

    2016-03-01

    We show how the spectrum of a radially symmetric Dirac Hamiltonian can be computed rather accurately on a spatial grid using a split-shift potential method. This method is sufficiently accurate such that the fine structure splittings of hydrogen-like relativistic ions with nuclear charge Z can be reproduced for a relatively small number of spatial radial grid points. We use this analytically known spectrum to examine the error scaling of this method. The method is then applied to examine the impact of a spatial confinement on the fine structure splittings and the bound states for hydrogen.

  5. Experience with the matched filtered weighted-shift-and-add method

    NASA Technical Reports Server (NTRS)

    Hege, E. Keith; Strobel, Nicolas V.; Ribak, Erez; Christou, Julian C.

    1987-01-01

    It is presently demonstrated that while the matched filter formulated by Ribak (1986) for the extension of the weighted-shift-and-add (WSA) method successfully reduces photon statistics-dominated specklegrams, the iterative method originally proposed by Ribak does not converge in the case of photon-noisy specklegrams for objects having more than one maxima. Attention is accordingly given to methods for rendering the procedure more 'artificially intelligent'. An error matrix is defined that is useful in evaluating the validity of the results produced by the matched filter extension of the WSA method.

  6. Absolute testing of flats in sub-stitching interferometer by rotation-shift method

    NASA Astrophysics Data System (ADS)

    Jia, Xin; Xu, Fuchao; Xie, Weimin; Li, Yun; Xing, Tingwen

    2015-09-01

    Most of the commercial available sub-aperture stitching interferometers measure the surface with a standard lens that produces a reference wavefront, and the precision of the interferometer is generally limited by the standard lens. The test accuracy can be achieved by removing the error of reference surface by the absolute testing method. When the testing accuracy (repeatability and reproducibility) is close to 1nm, in addition to the reference surface, other factors will also affect the measuring accuracy such as environment, zoom magnification, stitching precision, tooling and fixture, the characteristics of optical materials and so on. We establish a stitching system in the thousand level cleanroom. The stitching system is including the Zygo interferometer, the motion system with Bilz active isolation system at level VC-F. We review the traditional absolute flat testing methods and emphasize the method of rotation-shift functions. According to the rotation-shift method we get the profile of the reference lens and the testing lens. The problem of the rotation-shift method is the tilt error. In the motion system, we control the tilt error no more than 4 second to reduce the error. In order to obtain higher testing accuracy, we analyze the influence surface shape measurement accuracy by recording the environment error with the fluke testing equipment.

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

    SciTech Connect

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

    2012-09-15

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

  8. Imaging and quantifying Brownian motion of micro- and nanoparticles using phase-resolved Doppler variance optical coherence tomography.

    PubMed

    Kim, Chang Soo; Qi, Wenjuan; Zhang, Jun; Kwon, Young Jik; Chen, Zhongping

    2013-03-01

    Different types and sizes of micro- and nanoparticles have been synthesized and developed for numerous applications. It is crucial to characterize the particle sizes. Traditional dynamic light scattering, a predominant method used to characterize particle size, is unable to provide depth resolved information or imaging functions. Doppler variance optical coherence tomography (OCT) measures the spectral bandwidth of the Doppler frequency shift due to the Brownian motion of the particles utilizing the phase-resolved approach and can provide quantitative information about particle size. Spectral bandwidths of Doppler frequency shifts for various sized particles were quantified and were demonstrated to be inversely proportional to the diameter of the particles. The study demonstrates the phase-resolved Doppler variance spectral domain OCT technique has the potential to be used to investigate the properties of particles in highly scattering media. PMID:23515863

  9. 3D Wind Reconstruction and Turbulence Estimation in the Boundary Layer from Doppler Lidar Measurements using Particle Method

    NASA Astrophysics Data System (ADS)

    Rottner, L.; Baehr, C.

    2014-12-01

    Turbulent phenomena in the atmospheric boundary layer (ABL) are characterized by small spatial and temporal scales which make them difficult to observe and to model.New remote sensing instruments, like Doppler Lidar, give access to fine and high-frequency observations of wind in the ABL. This study suggests to use a method of nonlinear estimation based on these observations to reconstruct 3D wind in a hemispheric volume, and to estimate atmospheric turbulent parameters. The wind observations are associated to particle systems which are driven by a local turbulence model. The particles have both fluid and stochastic properties. Therefore, spatial averages and covariances may be deduced from the particles. Among the innovative aspects, we point out the absence of the common hypothesis of stationary-ergodic turbulence and the non-use of particle model closure hypothesis. Every time observations are available, 3D wind is reconstructed and turbulent parameters such as turbulent kinectic energy, dissipation rate, and Turbulent Intensity (TI) are provided. This study presents some results obtained using real wind measurements provided by a five lines of sight Lidar. Compared with classical methods (e.g. eddy covariance) our technic renders equivalent long time results. Moreover it provides finer and real time turbulence estimations. To assess this new method, we suggest computing independently TI using different observation types. First anemometer data are used to have TI reference.Then raw and filtered Lidar observations have also been compared. The TI obtained from raw data is significantly higher than the reference one, whereas the TI estimated with the new algorithm has the same order.In this study we have presented a new class of algorithm to reconstruct local random media. It offers a new way to understand turbulence in the ABL, in both stable or convective conditions. Later, it could be used to refine turbulence parametrization in meteorological meso-scale models.

  10. Noninvasive Method for Measuring Local Pulse Wave Velocity by Dual Pulse Wave Doppler: In Vitro and In Vivo Studies

    PubMed Central

    Wang, Zhen; Yang, Yong; Yuan, Li-jun; Liu, Jie; Duan, Yun-you; Cao, Tie-sheng

    2015-01-01

    Objectives To evaluate the validity and reproducibility of a noninvasive dual pulse wave Doppler (DPWD) method, which involves simultaneous recording of flow velocity of two independent sample volumes with a measurable distance, for measuring the local arterial pulse wave velocity (PWV) through in vitro and in vivo studies. Methods The DPWD mode of Hitachi HI Vision Preirus ultrasound system with a 5–13MHz transducer was used. An in vitro model was designed to compare the PWV of a homogeneous rubber tubing with the local PWV of its middle part measured by DPWD method. In the in vivo study, local PWV of 45 hypertensive patients (25 male, 49.8±3.1 years) and 45 matched healthy subjects (25 male, 49.3±3.0 years) were investigated at the left common carotid artery (LCCA) by DPWD method. Results In the in vitro study, the local PWV measured by DPWP method and the PWV of the homogeneous rubber tubing did not show statistical difference (5.16 ± 0.28 m/s vs 5.03 ± 0.15 m/s, p = 0.075). The coefficient of variation (CV) of the intra- and inter- measurements for local PWV were 3.46% and 4.96%, for the PWV of the homogeneous rubber tubing were 0.99% and 1.98%. In the in vivo study, a significantly higher local PWV of LCCA was found in the hypertensive patients as compared to that in healthy subjects (6.29±1.04m/s vs. 5.31±0.72m/s, P = 0.019). The CV of the intra- and inter- measurements in hypertensive patients were 2.22% and 3.94%, in healthy subjects were 2.07% and 4.14%. Conclusions This study demonstrated the feasibility of the noninvasive DPWD method to determine the local PWV, which was accurate and reproducible not only in vitro but also in vivo studies. This noninvasive echocardiographic method may be illuminating to clinical use. PMID:25786124

  11. Approaches for Improved Doppler Estimation in Lidar Remote Sensing of Atmospheric Dynamics

    NASA Astrophysics Data System (ADS)

    Bhaskaran, Sreevatsan; Calhoun, Ronald

    2016-06-01

    Laser radar (Lidar) has been used extensively for remote sensing of wind patterns, turbulence in the atmospheric boundary layer and other important atmospheric transport phenomenon. As in most narrowband radar application, radial velocity of remote objects is encoded in the Doppler shift of the backscattered signal relative to the transmitted signal. In contrast to many applications, however, the backscattered signal in atmospheric Lidar sensing arises from a multitude of moving particles in a spatial cell under examination rather than from a few prominent "target" scattering features. This complicates the process of extracting a single Doppler value and corresponding radial velocity figure to associate with the cell. This paper summarizes the prevalent methods for Doppler estimation in atmospheric Lidar applications and proposes a computationally efficient scheme for improving Doppler estimation by exploiting the local structure of spectral density estimates near spectral peaks.

  12. VizieR Online Data Catalog: Spectroscopy at the solar limb. I. Average off-limb profiles and Doppler shifts of Ca II H.

    NASA Astrophysics Data System (ADS)

    Beck, C.; Rezaei, R.

    2011-10-01

    The data used in the publication consist of a set of CaII H spectra taken near and beyond the solar limb on 25/08/2009 at UT 08:43-09:15. The data were obtained with the POLIS instrument at the German VTT. The wavelength range covers the core and the blue wing of the CaII H line from 396.332nm to 396.969nm in 326 steps of 1.96pm. The observations were done by moving the solar image across the slit of the spectrograph with a step width of 0.3-arcsec, yielding in total 134 slit spectra of 326 wavelength points on 244 CCD rows along the slit. The spatial sampling along the slit was 0.3-arcsec. The center of the field-of-view was located at (x,y)=(+37",+920") relative to the center of the solar disk. The data have been corrected for stray-light with the methods described in the article and are normalized to the continuum intensity on disc center. The corresponding data file data.fit is organized as floating array (x,y,wavelength)=(134x244x326) pixels. (1 data file).

  13. Rotational Doppler effect in nonlinear optics

    NASA Astrophysics Data System (ADS)

    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.

  14. A comparison of de-noising methods for differential phase shift and associated rainfall estimation

    NASA Astrophysics Data System (ADS)

    Hu, Zhiqun; Liu, Liping; Wu, Linlin; Wei, Qing

    2015-04-01

    Measured differential phase shift UDP is known to be a noisy unstable polarimetric radar variable, such that the quality of UDP data has direct impact on specific differential phase shift KDP estimation, and subsequently, the KDP-based rainfall estimation. Over the past decades, many UDP de-noising methods have been developed; however, the de-noising effects in these methods and their impact on KDP-based rainfall estimation lack comprehensive comparative analysis. In this study, simulated noisy UDP data were generated and de-noised by using several methods such as finite-impulse response (FIR), Kalman, wavelet, traditional mean, and median filters. The biases were compared between KDP from simulated and observed UDP radial profiles after de-noising by these methods. The results suggest that the complicated FIR, Kalman, and wavelet methods have a better de-noising effect than the traditional methods. After UDP was de-noised, the accuracy of the KDP-based rainfall estimation increased significantly based on the analysis of three actual rainfall events. The improvement in estimation was more obvious when KDP was estimated with UDP de-noised by Kalman, FIR, and wavelet methods when the average rainfall was heavier than 5 mm h ≥1. However, the improved estimation was not significant when the precipitation intensity further increased to a rainfall rate beyond 10 mm h ≥1. The performance of wavelet analysis was found to be the most stable of these filters.

  15. Doppler tracking

    NASA Astrophysics Data System (ADS)

    Thomas, Christopher Jacob

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

  16. Application of thermal wave imaging and phase shifting method for defect detection in Stainless steel

    NASA Astrophysics Data System (ADS)

    Shrestha, Ranjit; Park, Jeonghak; Kim, Wontae

    2016-05-01

    This paper presents an experimental arrangement for detection of artificial subsurface defects in a stainless steel sample by means of thermal wave imaging with lock-in thermography and consequently, the impact of excitation frequency on defect detectability. The experimental analysis was performed at several excitation frequencies to observe the sample beginning from 0.18 Hz all the way down to 0.01 Hz. The phase contrast between the defective and sound regions illustrates the qualitative and quantitative investigation of defects. The two, three, four and five-step phase shifting methods are investigated to obtain the information on defects. A contrast to noise ratio analysis was applied to each phase shifting method allowing the choice of the most appropriate one. Phase contrast with four-step phase shifting at an optimum frequency of 0.01 Hz provides excellent results. The inquiry with the effect of defect size and depth on phase contrast shows that phase contrast decreases with increase in defect depth and increases with the increase in defect size.

  17. Doppler-corrected differential detection system

    NASA Technical Reports Server (NTRS)

    Simon, Marvin K. (Inventor); Divsalar, Dariush (Inventor)

    1991-01-01

    Doppler in a communication system operating with a multiple differential phase-shift-keyed format (MDPSK) creates an adverse phase shift in an incoming signal. An open loop frequency estimation is derived from a Doppler-contaminated incoming signal. Based upon the recognition that, whereas the change in phase of the received signal over a full symbol contains both the differentially encoded data and the Doppler induced phase shift, the same change in phase over half a symbol (within a given symbol interval) contains only the Doppler induced phase shift, and the Doppler effect can be estimated and removed from the incoming signal. Doppler correction occurs prior to the receiver's final output of decoded data. A multiphase system can operate with two samplings per symbol interval at no penalty in signal-to-noise ratio provided that an ideal low pass pre-detection filter is employed, and two samples, at 1/4 and 3/4 of the symbol interval T sub s, are taken and summed together prior to incoming signal data detection.

  18. Atomic frequency standard relativistic Doppler shift experiment

    NASA Technical Reports Server (NTRS)

    Peters, H. E.; Reinhardt, V. S.

    1974-01-01

    An experiment has been performed to measure possible space anisotropy as it would effect the frequency of a cesium atomic beam standard clock in a laboratory on earth due to motion relative to external coordinate frames. The cesium frequency was measured as a function of orientation with respect to an atomic hydrogen maser standard. Over a period of 34 days 101 measurements were made. The results are consistent with a conclusion that no general orientation dependance attributable to spacial anisotropy was observed. It is shown that both the airplane clock results, and the null results for the atomic beam clock, are consistent with Einstein general or special relativity, or with the Lorentz transformations alone.

  19. Using Neural Networks for 13C NMR Chemical Shift Prediction-Comparison with Traditional Methods

    NASA Astrophysics Data System (ADS)

    Meiler, Jens; Maier, Walter; Will, Martin; Meusinger, Reinhard

    2002-08-01

    Interpretation of 13C chemical shifts is essential for structure elucidation of organic molecules by NMR. In this article, we present an improved neural network approach and compare its performance to that of commonly used approaches. Specifically, our recently proposed neural network ( J. Chem. Inf. Comput. Sci. 2000, 40, 1169-1176) is improved by introducing an extended hybrid numerical description of the carbon atom environment, resulting in a standard deviation (std. dev.) of 2.4 ppm for an independent test data set of ˜42,500 carbons. Thus, this neural network allows fast and accurate 13C NMR chemical shift prediction without the necessity of access to molecule or fragment databases. For an unbiased test dataset containing 100 organic structures the accuracy of the improved neural network was compared to that of a prediction method based on the HOSE code ( hierarchically ordered spherical description of environment) using S PECI NFO. The results show the neural network predictions to be of quality (std. dev.=2.7 ppm) comparable to that of the HOSE code prediction (std. dev.=2.6 ppm). Further we compare the neural network predictions to those of a wide variety of other 13C chemical shift prediction tools including incremental methods (C HEMD RAW, S PECT OOL), quantum chemical calculation (G AUSSIAN, C OSMOS), and HOSE code fragment-based prediction (S PECI NFO, ACD/CNMR, P REDICTI T NMR) for the 47 13C-NMR shifts of Taxol, a natural product including many structural features of organic substances. The smallest standard deviations were achieved here with the neural network (1.3 ppm) and S PECI NFO (1.0 ppm).

  20. SU-E-J-126: An Online Replanning Method for FFF Beams Without Couch Shift

    SciTech Connect

    Ahunbay, E; Ates, O; Li, X

    2015-06-15

    Purpose: In a situation that couch shift for patient positioning is not preferred or prohibited (e.g., MR-Linac), segment aperture morphing (SAM) can address target dislocation and deformation. For IMRT/VMAT with flattening filter free (FFF) beams, however, SAM method would lead to an adverse translational dose effect due to the beam unflattening. Here we propose a new 2-step process to address both the translational effect of FFF beams and the target deformation. Methods: The replanning method consists of an offline and an online steps. The offline step is to create a series of pre-shifted plans (PSP) obtained by a so called “warm start” optimization (starting optimization from the original plan, rather from scratch) at a series of isocenter shifts with fixed distance (e.g. 2 cm, at x,y,z = 2,0,0 ; 2,2,0 ; 0,2,0; …;− 2,0,0). The PSPs all have the same number of segments with very similar shapes, since the warm-start optimization only adjusts the MLC positions instead of regenerating them. In the online step, a new plan is obtained by linearly interpolating the MLC positions and the monitor units of the closest PSPs for the shift determined from the image of the day. This two-step process is completely automated, and instantaneously fast (no optimization or dose calculation needed). The previously-developed SAM algorithm is then applied for daily deformation. We tested the method on sample prostate and pancreas cases. Results: The two-step interpolation method can account for the adverse dose effects from FFF beams, while SAM corrects for the target deformation. The whole process takes the same time as the previously reported SAM process (5–10 min). Conclusion: The new two-step method plus SAM can address both the translation effects of FFF beams and target deformation, and can be executed in full automation requiring no additional time from the SAM process. This research was supported by Elekta inc. (Crawley, UK)

  1. Structured-illumination photoacoustic Doppler flowmetry of axial flow in homogeneous scattering media.

    PubMed

    Zhang, Ruiying; Yao, Junjie; Maslov, Konstantin I; Wang, Lihong V

    2013-08-26

    We propose a method for photoacoustic flow measurement based on the Doppler effect from a flowing homogeneous medium. Excited by spatially modulated laser pulses, the flowing medium induces a Doppler frequency shift in the received photoacoustic signals. The frequency shift is proportional to the component of the flow speed projected onto the acoustic beam axis, and the sign of the shift reflects the flow direction. Unlike conventional flowmetry, this method does not rely on particle heterogeneity in the medium; thus, it can tolerate extremely high particle density. A red-ink phantom flowing in a tube immersed in water was used to validate the method in both the frequency and time domains. The phantom flow immersed in an intralipid solution was also measured. PMID:24065864

  2. A new method for detecting velocity shifts and distortions between optical spectra

    SciTech Connect

    Evans, Tyler M.; Murphy, Michael T.

    2013-12-01

    Recent quasar spectroscopy from the Very Large Telescope (VLT) and Keck suggests that fundamental constants may not actually be constant. To better confirm or refute this result, systematic errors between telescopes must be minimized. We present a new method to directly compare spectra of the same object and measure any velocity shifts between them. This method allows for the discovery of wavelength-dependent velocity shifts between spectra, i.e., velocity distortions, that could produce spurious detections of cosmological variations in fundamental constants. This 'direct comparison' method has several advantages over alternative techniques: it is model-independent (cf. line-fitting approaches), blind, in that spectral features do not need to be identified beforehand, and it produces meaningful uncertainty estimates for the velocity shift measurements. In particular, we demonstrate that, when comparing echelle-resolution spectra with unresolved absorption features, the uncertainty estimates are reliable for signal-to-noise ratios ≳7 per pixel. We apply this method to spectra of quasar J2123–0050 observed with Keck and the VLT and find no significant distortions over long wavelength ranges (∼1050 Å) greater than ≈180 m s{sup –1}. We also find no evidence for systematic velocity distortions within echelle orders greater than 500 m s{sup –1}. Moreover, previous constraints on cosmological variations in the proton-electron mass ratio should not have been affected by velocity distortions in these spectra by more than 4.0 ± 4.2 parts per million. This technique may also find application in measuring stellar radial velocities in search of extra-solar planets and attempts to directly observe the expansion history of the universe using quasar absorption spectra.

  3. CD-SEM image-distortion measured by view-shift method

    NASA Astrophysics Data System (ADS)

    Inoue, Osamu; Kawasaki, Takahiro; Matsui, Miyako; Kawada, Hiroki

    2011-03-01

    As the design rule for semiconductor device shrinks, metrology for the critical dimension scanning electron microscope (CD-SEM) is not only for measuring the dimension but also the shape, such as 2D contour of hot-spot pattern and OPC calibration-pattern. Accuracy of the shape metrology is dependent on distortion of CD-SEM image. The distortion of magnification in horizontal direction (i.e. x-direction) can be measured by pitch-calibration method, that measures pitch of identical vertical line patterns while view-shifting the identical pitch in x-direction. However, the number of measurement point could not be sufficient because this method requires long measurement time. Not only the horizontal magnification but also vertical magnification (i.e. y-direction) and shear deformation (i.e. distortion of shape) are necessary to keep highly accurate measurement. In this paper we introduce the view-shift method for quick and accurate measurement of the image-distortion. From using this method, both local distortion of magnification and shape can be measured in horizontal and vertical directions at once. Firstly, two SEM-images of evaluation sample are taken. The sample should have a lot of unique features, e.g. Textured-Silicon. View-shift about one ninth of the image size should be done by two images, and There are a lot of unique features in overlapped region between two images. As distribution of the unique features, displacement between two images indicates the local image-distortion. The dislocation of sample contour from distortion is estimated from the local-distortion. The image-dislocation on a tool evaluated in this paper is less than 0.5 nm. It is a tolerated size for current device process. However, it could be increased under the noisy external environment.

  4. Observation of the Zero Doppler Effect

    PubMed Central

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

    2016-01-01

    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. PMID:27046395

  5. Observation of the Zero Doppler Effect

    NASA Astrophysics Data System (ADS)

    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.

  6. Observation of the Zero Doppler Effect.

    PubMed

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

    2016-01-01

    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. PMID:27046395

  7. A Novel Method to Predict Genomic Islands Based on Mean Shift Clustering Algorithm.

    PubMed

    de Brito, Daniel M; Maracaja-Coutinho, Vinicius; de Farias, Savio T; Batista, Leonardo V; do Rêgo, Thaís G

    2016-01-01

    Genomic Islands (GIs) are regions of bacterial genomes that are acquired from other organisms by the phenomenon of horizontal transfer. These regions are often responsible for many important acquired adaptations of the bacteria, with great impact on their evolution and behavior. Nevertheless, these adaptations are usually associated with pathogenicity, antibiotic resistance, degradation and metabolism. Identification of such regions is of medical and industrial interest. For this reason, different approaches for genomic islands prediction have been proposed. However, none of them are capable of predicting precisely the complete repertory of GIs in a genome. The difficulties arise due to the changes in performance of different algorithms in the face of the variety of nucleotide distribution in different species. In this paper, we present a novel method to predict GIs that is built upon mean shift clustering algorithm. It does not require any information regarding the number of clusters, and the bandwidth parameter is automatically calculated based on a heuristic approach. The method was implemented in a new user-friendly tool named MSGIP--Mean Shift Genomic Island Predictor. Genomes of bacteria with GIs discussed in other papers were used to evaluate the proposed method. The application of this tool revealed the same GIs predicted by other methods and also different novel unpredicted islands. A detailed investigation of the different features related to typical GI elements inserted in these new regions confirmed its effectiveness. Stand-alone and user-friendly versions for this new methodology are available at http://msgip.integrativebioinformatics.me. PMID:26731657

  8. A Novel Method to Predict Genomic Islands Based on Mean Shift Clustering Algorithm

    PubMed Central

    de Brito, Daniel M.; Maracaja-Coutinho, Vinicius; de Farias, Savio T.; Batista, Leonardo V.; do Rêgo, Thaís G.

    2016-01-01

    Genomic Islands (GIs) are regions of bacterial genomes that are acquired from other organisms by the phenomenon of horizontal transfer. These regions are often responsible for many important acquired adaptations of the bacteria, with great impact on their evolution and behavior. Nevertheless, these adaptations are usually associated with pathogenicity, antibiotic resistance, degradation and metabolism. Identification of such regions is of medical and industrial interest. For this reason, different approaches for genomic islands prediction have been proposed. However, none of them are capable of predicting precisely the complete repertory of GIs in a genome. The difficulties arise due to the changes in performance of different algorithms in the face of the variety of nucleotide distribution in different species. In this paper, we present a novel method to predict GIs that is built upon mean shift clustering algorithm. It does not require any information regarding the number of clusters, and the bandwidth parameter is automatically calculated based on a heuristic approach. The method was implemented in a new user-friendly tool named MSGIP—Mean Shift Genomic Island Predictor. Genomes of bacteria with GIs discussed in other papers were used to evaluate the proposed method. The application of this tool revealed the same GIs predicted by other methods and also different novel unpredicted islands. A detailed investigation of the different features related to typical GI elements inserted in these new regions confirmed its effectiveness. Stand-alone and user-friendly versions for this new methodology are available at http://msgip.integrativebioinformatics.me. PMID:26731657

  9. A general chemical shift decomposition method for hyperpolarized (13) C metabolite magnetic resonance imaging.

    PubMed

    Wang, Jian-Xiong; Merritt, Matthew E; Sherry, Dean; Malloy, Craig R

    2016-08-01

    Metabolic imaging with hyperpolarized carbon-13 allows sequential steps of metabolism to be detected in vivo. Potential applications in cancer, brain, muscular, myocardial, and hepatic metabolism suggest that clinical applications could be readily developed. A primary concern in imaging hyperpolarized nuclei is the irreversible decay of the enhanced magnetization back to thermal equilibrium. Multiple methods for rapid imaging of hyperpolarized substrates and their products have been proposed with a multi-point Dixon method distinguishing itself as a robust protocol for imaging [1-(13) C]pyruvate. We describe here a generalized chemical shift decomposition method that incorporates a single-shot spiral imaging sequence plus a spectroscopic sequence to retain as much spin polarization as possible while allowing detection of metabolites that have a wide range of chemical shift values. The new method is demonstrated for hyperpolarized [1-(13) C]pyruvate, [1-(13) C]acetoacetate, and [2-(13) C]dihydroxyacetone. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27060361

  10. Evaluation of a hydrograph-shifting method for estimating suspended-sediment loads in Illinois streams

    USGS Publications Warehouse

    Frost, L.R.; Mansue, L.J.

    1984-01-01

    A hydrograph-shifting method for estimating monthly and annual suspended-sediment loads was applied to suspended-sediment records for 12 streams in Illinois. Transport equations for each station were developed and synthetic sediment-discharge hydrographs were then generated by using these transport equations and records of daily streamflow. Hydrographs were shifted to measured values of daily sediment discharge selected to represent weekly, biweekly, and monthly sampling frequencies. Estimates of monthly suspended-sediment load ranged from 16 to 326 percent of measured values. Estimates of annual suspended-sediment loads ranged from 41 to 136 percent of measured values. (The method provides a reasonable means of estimating annual loads for most sites.) An experiment designed to measure the subjectivity of the method showed it to be more dependent on the particular days selected as control points than on the person applying the method. An evaluation of the effect of the length of record used to develop transport equations was not conclusive. Although standard errors of estimate showed no improvement, the comparison of estimated loads with measured loads showed slight improvement when 1 or 2 years of data were added to the data used to develop transport equations. (USGS)

  11. Superresolution imaging method using phase-shifting digital lensless Fourier holography.

    PubMed

    Granero, Luis; Micó, Vicente; Zalevsky, Zeev; García, Javier

    2009-08-17

    A method which is useful for obtaining superresolved imaging in a digital lensless Fourier holographic configuration is presented. By placing a diffraction grating between the input object and the CCD recording device, additional high-order spatial-frequency content of the object spectrum is directed towards the CCD. Unlike other similar methods, the recovery of the different band pass images is performed by inserting a reference beam in on-axis mode and using phase-shifting method. This strategy provides advantages concerning the usage of the whole frequency plane as imaging plane. Thus, the method is no longer limited by the zero order term and the twin image. Finally, the whole process results in a synthetic aperture generation that expands up the system cutoff frequency and yields a superresolution effect. Experimental results validate our concepts for a resolution improvement factor of 3. PMID:19687979

  12. Laser double Doppler flowmeter

    NASA Astrophysics Data System (ADS)

    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.

  13. Evaluation method on steering for the shape-shifting robot in different configurations

    NASA Astrophysics Data System (ADS)

    Chang, Jian; Li, Bin; Wang, Chong; Zheng, Huaibing; Li, Zhiqiang

    2016-01-01

    The evaluation method on steering is based on qualitative manner in existence, which causes the result inaccurate and fuzziness. It reduces the efficiency of process execution. So the method by quantitative manner for the shape-shifting robot in different configurations is proposed. Comparing to traditional evaluation method, the most important aspects which can influence the steering abilities of the robot in different configurations are researched in detail, including the energy, angular velocity, time and space. In order to improve the robustness of system, the ideal and slippage conditions are all considered by mathematical model. Comparing to the traditional weighting confirming method, the extent of robot steering method is proposed by the combination of subjective and objective weighting method. The subjective weighting method can show more preferences of the experts and is based on five-grade scale. The objective weighting method is based on information entropy to determine the factors. By the sensors fixed on the robot, the contract force between track grouser and ground, the intrinsic motion characteristics of robot are obtained and the experiment is done to prove the algorithm which is proposed as the robot in different common configurations. Through the method proposed in the article, fuzziness and inaccurate of the evaluation method has been solved, so the operators can choose the most suitable configuration of the robot to fulfil the different tasks more quickly and simply.

  14. Generic Doppler processor speeds radar analysis

    NASA Astrophysics Data System (ADS)

    Engler, Harold F., Jr.; West, Philip D.; Austin, Mark D.; Gardos, Thomas R.

    1991-03-01

    The design and operation of a generic Doppler processor (GDP) are described in detail and illustrated with diagrams. The GDP was developed to facilitate the selection of a Doppler processing method for a radar system; it operates on an industrial desktop computer and makes it possible to switch rapidly among different Doppler processing bandwidths and center frequencies, filtering methods (FFT, analog, etc.), windowing methods, numbers of bits for quantization, and output display formats. The principal components are a programmable baseband clutter filter module, a Doppler processor chassis, a synthetic range-Doppler display, and a spectrum-analyzer-type real-Doppler display. The GDP provides + or - 5O kHz coverage with filter bandwidth 200 Hz, a maximum of 512 channels, 10 range gates, and an instantaneous dynamic range of 60 dB. Also discussed is the efficient finite-impulse-response filter design used to simulate analog filter banks.

  15. Calculation of NMR chemical shifts. 7. Gauge-invariant INDO method

    NASA Astrophysics Data System (ADS)

    Fukui, H.; Miura, K.; Hirai, A.

    A gauge-invariant INDO method based on the coupled Hartree-Fuck perturbation theory is presented and applied to the calculation of 1H and 13C chemical shifts of hydrocarbons including ring compounds. Invariance of the diamagnetic and paramagnetic shieldings with respect to displacement of the coordinate origin is discussed. Comparison between calculated and experimental results exhibits fairly good agreement, provided that the INDO parameters of Ellis et al. (J. Am. Chem. Soc.94, 4069 (1972)) are used with the inclusion of all multicenter one-electron integrals.

  16. Implementing torsional-mode Doppler ladar.

    PubMed

    Fluckiger, David U

    2002-08-20

    Laguerre-Gaussian laser modes carry orbital angular momentum as a consequence of their helical-phase front screw dislocation. This torsional beam structure interacts with rotating targets, changing the orbital angular momentum (azimuthal Doppler) of the scattered beam because angular momentum is a conserved quantity. I show how to measure this change independently from the usual longitudinal momentum (normal Doppler shift) and derive the apropos coherent mixing efficiencies for monostatic, truncated Laguerre and Gaussian-mode ladar antenna patterns. PMID:12206220

  17. Mycobacteria mobility shift assay: a method for the rapid identification of Mycobacterium tuberculosis and nontuberculous mycobacteria

    PubMed Central

    Wildner, Letícia Muraro; Bazzo, Maria Luiza; Liedke, Susie Coutinho; Nogueira, Christiane Lourenço; Segat, Gabriela; Senna, Simone Gonçalves; Schlindwein, Aline Daiane; de Oliveira, Jaquelline Germano; Rovaris, Darcita B; Bonjardim, Claudio A; Kroon, Erna G; Ferreira, Paulo CP

    2014-01-01

    The identification of mycobacteria is essential because tuberculosis (TB) and mycobacteriosis are clinically indistinguishable and require different therapeutic regimens. The traditional phenotypic method is time consuming and may last up to 60 days. Indeed, rapid, affordable, specific and easy-to-perform identification methods are needed. We have previously described a polymerase chain reaction-based method called a mycobacteria mobility shift assay (MMSA) that was designed for Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) species identification. The aim of this study was to assess the MMSA for the identification of MTC and NTM clinical isolates and to compare its performance with that of the PRA-hsp65 method. A total of 204 clinical isolates (102 NTM and 102 MTC) were identified by the MMSA and PRA-hsp65. For isolates for which these methods gave discordant results, definitive species identification was obtained by sequencing fragments of the 16S rRNA and hsp65 genes. Both methods correctly identified all MTC isolates. Among the NTM isolates, the MMSA alone assigned 94 (92.2%) to a complex or species, whereas the PRA-hsp65 method assigned 100% to a species. A 91.5% agreement was observed for the 94 NTM isolates identified by both methods. The MMSA provided correct identification for 96.8% of the NTM isolates compared with 94.7% for PRA-hsp65. The MMSA is a suitable auxiliary method for routine use for the rapid identification of mycobacteria. PMID:24821059

  18. A study on the digital nano-moiré method and its phase shifting technique

    NASA Astrophysics Data System (ADS)

    Xie, Huimin; Liu, Zhanwei; Fang, Daining; Dai, Fulong; Gao, Hongjun; Zhao, Yapu

    2004-09-01

    A novel digital nano-moiré method is proposed to measure the in-plane nanoscopic deformation of an object. In the measurement, the periodic lattice of a single-crystal material acts as a specimen grating while a digital reference grating (DRG) is prepared by computer software. These two gratings overlap to generate a moiré fringe pattern. The preparation of the grating, the formation principle of digital nano-moiré fringes and its relative phase shifting technique are described in detail. A typical experiment was conducted with a highly oriented pyrolytic graphite (HOPG) sample. The residual deformation of the irradiated HOPG sample was measured using this method. The experiment result verifies the feasibility of this method, and demonstrates the potential for further applications.

  19. Acoustic attenuation logging using centroid frequency shift and amplitude ratio methods: A numerical study

    SciTech Connect

    Quan, Y.; Harris, J.M.; Chen, X.

    1994-12-31

    The centroid frequency shift method is proposed to estimate seismic attenuation from full waveform acoustic logs. This approach along with the amplitude ratio method is applied to investigate the attenuation properties of the P head wave in fluid-filled boreholes. The generalized reflection and transmission coefficients method is used to perform forward modeling. The authors suggest an empirical formula to describe the frequency-dependent geometrical spreading of the P-wave in a borehole. They simulate a more realistic borehole by including a mudcake and an invaded zone which are modeled by a large number of radially symmetric thin layers. The numerical tests show that this invaded zone exhibits very strong influence on the attenuation measurement.

  20. Laser Doppler velocimetry primer

    NASA Technical Reports Server (NTRS)

    Bachalo, William D.

    1985-01-01

    Advanced research in experimental fluid dynamics required a familiarity with sophisticated measurement techniques. In some cases, the development and application of new techniques is required for difficult measurements. Optical methods and in particular, the laser Doppler velocimeter (LDV) are now recognized as the most reliable means for performing measurements in complex turbulent flows. And such, the experimental fluid dynamicist should be familiar with the principles of operation of the method and the details associated with its application. Thus, the goals of this primer are to efficiently transmit the basic concepts of the LDV method to potential users and to provide references that describe the specific areas in greater detail.

  1. High resolution Doppler lidar

    NASA Technical Reports Server (NTRS)

    Abreu, Vincent J.; Hays, Paul B.; Barnes, John E.

    1989-01-01

    A high resolution lidar system was implemented to measure winds in the lower atmosphere. The wind speed along the line of sight was determined by measuring the Doppler shift of the aerosol backscattered laser signal. The system in its present configuration is stable, and behaves as indicated by theoretical simulations. This system was built to demonstrate the capabilities of the detector system as a prototype for a spaceborne lidar. The detector system investigated consisted of a plane Fabry-Perot etalon, and a 12-ring anode detector. This system is generically similar to the Fabry-Perot interferometer developed for passive wind measurements on board the Dynamics Explorer satellite. That this detector system performs well in a lidar configuration was demonstrated.

  2. Reproducibility of contact lens power measurements using the phase shifting schlieren method

    NASA Astrophysics Data System (ADS)

    Joannes, Luc; Hough, Tony; Hutsebaut, Xavier; Dubois, Xavier; Ligot, Renaud; Saoul, Bruno; Van Donink, Philip; De Coninck, Kris

    2009-06-01

    PURPOSE. To assess a new method of power measurement of soft and rigid contact lenses. The method is the phase shifting schlieren method, as embodied in the Nimo TR1504 instrument. MATERIALS and METHODS. Three Nimo TR1504 instruments were used to measure the power related dimensions of: a) a range of custom toric rigid lenses; b) a range of commercially available spherical hydrogel lenses; and c) a commercially available range of toric silicone hydrogel lenses. The measurements were carried out using a standard ISO ring test protocol where independent tests were carried out under conditions of reproducibility. The analysis of the measurements was carried out using ISO methods which enabled the reproducibility standard deviation, SR, of the method to be calculated. RESULTS. The results show that this new method has a reproducibility standard deviation SR of 0.048D for spherical soft (hydrogel) lenses. This means the back vertex power of spherical soft lenses having a power in the range +/-20.0D can be determined to current ISO product tolerances with a single measurement. The method has SR of 0.059D for sphere power and 0.093D for cylinder power for toric soft lenses having powers in the range +/-10.0D and cylinder powers in the range +/-2.0D. A single measurement will determine sphere power to current ISO tolerance limits with 95% confidence while two measurements are required to determine the cylinder power to the same confidence level.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  4. Spectroscopic studies of biologically active coumarin laser dye: Evaluation of dipole moments by solvatochromic shift method

    NASA Astrophysics Data System (ADS)

    Koppal, V. V.; Muddapur, G. V.; Patil, N. R.; Melavanki, R. M.

    2016-05-01

    In this paper we attempted to record absorption and emission spectra of 2-acetyl-3H-benzo[f]chromen-3-one [2AHBC] laser dye in different solvents of varying polarities to investigate its solvatochromic behavior. The two electronic states dipole moments of 2AHBC are calculated using solvatochromic spectral shifts which are correlated with dielectric constant (ɛ) refractive index (n) of various solvents. A systematic approach is made to estimate ground and excited state dipole moments on the basis of different solvent correlation methods like Bilot-Kawski equations, Lippert-Mataga, Bakhsheiv, Kawaski-Chamma-Viallet and Reichardt methods. Dipole moments in the excited state was found to be higher than the ground state by confirming π→π* transition.

  5. Doppler-corrected differential detection of MPSK

    NASA Technical Reports Server (NTRS)

    Simon, Marvin K.; Divsalar, Dariush

    1989-01-01

    An open-loop technique is presented for estimating and correcting Doppler frequency shift in an M-ary differential phase-shift-keyed (MDPSK) receiver. The novelty of the scheme is based on the observation that whereas the change in phase of the received signal over a full symbol contains the sum of the data (phase) and the Doppler-induced phase shift, the same change in phase over half a symbol (within a given symbol interval) contains only the Doppler-induced phase shift. Thus, by proper processing, the latter can be estimated and removed from the former. Analytical and simulation results are given for the variance of the above estimator, and the error probability performance of the MDPSK receiver is evaluated in the presence of the Doppler correction. Next, the practical considerations associated with the application of this technique on bandlimited Nyquist channels are discussed and incorporated into the final design. It is shown that the receiver can, in the absence of timing jitter, be designed to allow combined Doppler correction and data detection with no penalty due to intersymbol interference (ISI). The effects of ISI due to timing jitter are assessed by computer simulation.

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

    NASA Astrophysics Data System (ADS)

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

    1995-02-01

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

  7. The delta Doppler technique for LDV measurements at long distances

    NASA Technical Reports Server (NTRS)

    Cliff, W. C.

    1976-01-01

    A technique for measuring velocity, referred to as a Delta Doppler technique, was presented. This technique determines scattering source velocities by measuring the difference in Doppler shifts of two different frequencies. By transmitting the two frequencies along the same path, a moving fringe pattern is established such that a nonmoving scatterer at the sensing volume would see an intensity variation exactly equal to the difference in the transmitted frequencies. If the particle has a velocity component along an axis which bisects the angle formed by the transmitter and receiver axes, a Doppler shift in the difference frequency can be measured and the velocity component computed. The frequency measured would correspond to the difference in Doppler frequencies that two laser Doppler velocimeters using separate frequencies (the same frequencies as used previously) would have measured, thus the term Delta Doppler.

  8. Detection of peripheral arterial disease with an improved automated device: comparison of a new oscillometric device and the standard Doppler method.

    PubMed

    Špan, Matjaž; Geršak, Gregor; Millasseau, Sandrine C; Meža, Marko; Košir, Andrej

    2016-01-01

    In occidental countries, peripheral arterial disease (PAD) is an important health issue; however, most subjects are asymptomatic (~50%) and therefore undiagnosed and untreated. Current guidelines recommend screening for PAD in primary care setting using ankle brachial index (ABI) in all patients with cardiovascular risks. This is, however, not performed strictly because the standard Doppler method is cumbersome and time-consuming. Here, we evaluate the accuracy and reproducibility of ABI measurements obtained by an improved automated oscillometric device, the MESI ABPI MD(®) device, and the standard Doppler method. ABI was measured in random order in a general practice with Doppler probes by two operators separately (ABI_dop) and twice with the MESI ABPI MD device (ABI_mesi). ABI_dop was calculated dividing the highest systolic blood pressure from both tibial and dorsalis pedis arteries by the highest systolic blood pressure of both brachial arteries. ABI_mesi was obtained automatically with simultaneous measurements on three extremities. According to ABI_dop, PAD was present in 10% of the 136 screened subjects (68.2±7.4 years). Interoperator coefficient of variation was 5.5% for ABI_dop, while the intrasubject coefficient of variation for ABI_mesi was 3.0%. ABI_mesi was correlated with ABI_dop (R=0.61, P<0.0001). The difference between the two techniques was 0.06±0.14 with ABI_mesi providing slightly higher values (P<0.0001) and negligible bias across the range (R=0.19, P<0.0001). Therefore, ABI_mesi ≤1 had a sensitivity of 85% and specificity of 96% to detect ABI_dop ≤0.9 and hence PAD. Doppler measurements took seven times longer than MESI ABPI MD measurements to be performed. In conclusion, MESI improved automated oscillometric method and offered a faster and repeatable measurement of ABI with only a small, clinically irrelevant overestimation of ABI value. The tested MESI ABPI MD-improved oscillometric system can be used as a screening tool for patients

  9. Detection of peripheral arterial disease with an improved automated device: comparison of a new oscillometric device and the standard Doppler method

    PubMed Central

    Špan, Matjaž; Geršak, Gregor; Millasseau, Sandrine C; Meža, Marko; Košir, Andrej

    2016-01-01

    In occidental countries, peripheral arterial disease (PAD) is an important health issue; however, most subjects are asymptomatic (~50%) and therefore undiagnosed and untreated. Current guidelines recommend screening for PAD in primary care setting using ankle brachial index (ABI) in all patients with cardiovascular risks. This is, however, not performed strictly because the standard Doppler method is cumbersome and time-consuming. Here, we evaluate the accuracy and reproducibility of ABI measurements obtained by an improved automated oscillometric device, the MESI ABPI MD® device, and the standard Doppler method. ABI was measured in random order in a general practice with Doppler probes by two operators separately (ABI_dop) and twice with the MESI ABPI MD device (ABI_mesi). ABI_dop was calculated dividing the highest systolic blood pressure from both tibial and dorsalis pedis arteries by the highest systolic blood pressure of both brachial arteries. ABI_mesi was obtained automatically with simultaneous measurements on three extremities. According to ABI_dop, PAD was present in 10% of the 136 screened subjects (68.2±7.4 years). Interoperator coefficient of variation was 5.5% for ABI_dop, while the intrasubject coefficient of variation for ABI_mesi was 3.0%. ABI_mesi was correlated with ABI_dop (R=0.61, P<0.0001). The difference between the two techniques was 0.06±0.14 with ABI_mesi providing slightly higher values (P<0.0001) and negligible bias across the range (R=0.19, P<0.0001). Therefore, ABI_mesi ≤1 had a sensitivity of 85% and specificity of 96% to detect ABI_dop ≤0.9 and hence PAD. Doppler measurements took seven times longer than MESI ABPI MD measurements to be performed. In conclusion, MESI improved automated oscillometric method and offered a faster and repeatable measurement of ABI with only a small, clinically irrelevant overestimation of ABI value. The tested MESI ABPI MD-improved oscillometric system can be used as a screening tool for patients

  10. Fluid Shifts

    NASA Technical Reports Server (NTRS)

    Stenger, Michael; Hargens, A.; Dulchavsky, S.; Ebert, D.; Lee, S.; Sargsyan, A.; Martin, D.; Lui, J.; Macias, B.; Arbeille, P.; Platts, S.

    2014-01-01

    ); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid pulsatility); (5) ocular measures (optical coherence tomography, intraocular pressure, 2-dimensional ultrasound including optic nerve sheath diameter, globe flattening, and retina-choroid thickness, Doppler ultrasound of ophthalmic and retinal arteries, and veins); (6) cardiac variables by ultrasound (inferior vena cava, tricuspid flow and tissue Doppler, pulmonic valve, stroke volume, right heart dimensions and function, four-chamber views); and (7) ICP measures (tympanic membrane displacement, distortion-product otoacoustic emissions, and ICP calculated by MRI). On the ground, acute head-down tilt will induce cephalad fluid shifts, whereas LBNP will oppose these shifts. Controlled Mueller maneuvers will manipulate cardiovascular variables. Through interventions applied before, during, and after flight, we intend to fully evaluate the relationship between fluid shifts and the VIIP syndrome. This study has been selected for flight implementation and is one of the candidate investigations being considered for the one year mission.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  12. Development of Point Doppler Velocimetry for Flow Field Investigations

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    A Point Doppler Velocimeter (pDv) has been developed using a vapor-limited iodine cell as the sensing medium. The iodine cell is utilized to directly measure the Doppler shift frequency of laser light scattered from submicron particles suspended within a fluid flow. The measured Doppler shift can then be used to compute the velocity of the particles, and hence the fluid. Since this approach does not require resolution of scattered light from individual particles, the potential exists to obtain temporally continuous signals that could be uniformly sampled in the manner as a hot wire anemometer. This leads to the possibility of obtaining flow turbulence power spectra without the limitations of fringe-type laser velocimetry. The development program consisted of a methodical investigation of the technology coupled with the solution of practical engineering problems to produce a usable measurement system. The paper outlines this development along with the evaluation of the resulting system as compared to primary standards and other measurement technologies.

  13. Method and apparatus for executing an asynchronous clutch-to-clutch shift in a hybrid transmission

    DOEpatents

    Demirovic, Besim; Gupta, Pinaki; Kaminsky, Lawrence A.; Naqvi, Ali K.; Heap, Anthony H.; Sah, Jy-Jen F.

    2014-08-12

    A hybrid transmission includes first and second electric machines. A method for operating the hybrid transmission in response to a command to execute a shift from an initial continuously variable mode to a target continuously variable mode includes increasing torque of an oncoming clutch associated with operating in the target continuously variable mode and correspondingly decreasing a torque of an off-going clutch associated with operating in the initial continuously variable mode. Upon deactivation of the off-going clutch, torque outputs of the first and second electric machines and the torque of the oncoming clutch are controlled to synchronize the oncoming clutch. Upon synchronization of the oncoming clutch, the torque for the oncoming clutch is increased and the transmission is operated in the target continuously variable mode.

  14. Simple Method for Study of Single-mode Dispersion-shifted and Dispersion-flattened Fibers

    NASA Astrophysics Data System (ADS)

    Bose, Ashima; Gangopadhyay, S.; Saha, S. C.

    2012-12-01

    Employing the simple series expression based on Chebyshev technique, we predict the fundamental modal field inside the core as well as cladding in case of dispersion-shifted trapezoidal and dispersion-flattened graded and step W fibers. This formalism also estimates cladding decay parameters (W) of the said fibers. The analysis involves use of a linear relationship of the ratio of first and zero order modified Bessel functions in the form with 1/W over a wide and practical range of W values appropriate for guidance of only fundamental mode in such fibers. The present method prescribes analytical expressions for the concerned propagation characteristics and these are executable with little computations. Our results are found to match excellently with the available exact results.

  15. Fish protein recovered using ph shifting method and its physicochemical properties

    NASA Astrophysics Data System (ADS)

    Choi, J. Yeung; Kim, Jinx-Soo

    2005-07-01

    The solubility of meat protein of croaker and jack mackerel was significantly affected by pH shifting. The protein yield of alkali-aided processing is higher than those of conventional and acid-aided processing. The addition of sarcoplasmic protein increases the breaking force and deformation value. The breaking force of recovered protein gel from alkali-aided processing is decreased by the addition of NaCl. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that fish protein of alkali is similar to that at pH7.0. Alkali-aided processing for recovering fish protein is a valuable method for increasing the utilization of frozen and pelagic fishes and for making kamaboko products.

  16. Optical frequency standards for gravitational wave detection using satellite Doppler velocimetry

    NASA Astrophysics Data System (ADS)

    Vutha, Amar

    2015-06-01

    Gravitational waves (GWs) imprint apparent Doppler shifts on the frequency of photons propagating between an emitter and detector of light. This forms the basis of a method to detect GWs using Doppler velocimetry between pairs of satellites. Operating in the micro-hertz to milli-hertz gravitational frequency band, this method could lead to the direct detection of GWs. The crucial component in such detectors is the frequency standard on board the emitting and receiving satellites. Recent developments in atomic frequency standards have led to devices that are approaching the sensitivity required to detect GWs from astrophysically interesting sources. The sensitivity of satellites equipped with optical frequency standards for Doppler velocimetry is examined, and a design for a robust, space-capable optical frequency standard is presented.

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  19. Parallax effects in laser Doppler spectroscopy

    SciTech Connect

    Smirnov, V I

    1999-12-31

    Parallax effects in laser Doppler spectroscopy, associated with the variation of the scattering angle during motion of a particle through the probed volume, were investigated by a numerical simulation method based on the Mie scattering theory. It was found that, in general, the shifts of the spectral profile parameters (the average frequency, broadening, asymmetry, and kurtosis) become significant as the parallax number N{sub {psi}{alpha}=}(2/{pi}){psi}{alpha} ({psi} is the angular size of the probed volume, {alpha} = {pi}d/{lambda} is the relative particle diameter) increases. The anomalous ranges of the parameters of the particle and of the optical system, in which marked distortions (such as the polymodal nature and the splitting of the spectral profile) are observed even for a low parallax number (N{sub {psi}{alpha}} || 1), were discovered. (laser applications and other topics in quantum electronics)

  20. A study for developing an ultrasonic Doppler flowmeter

    NASA Astrophysics Data System (ADS)

    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%.

  1. Imaging doppler velocimeter with downward heterodyning in the optical domain

    DOEpatents

    Reu, Phillip L; Hansche, Bruce D

    2013-05-21

    In a Doppler velocimeter, the incoming Doppler-shifted beams are heterodyned to reduce their frequencies into the bandwidth of a digital camera. This permits the digital camera to produce at every sampling interval a complete two-dimensional array of pixel values. This sequence of pixel value arrays provides a velocity image of the target.

  2. Phase correction method for least-squares wavefront calculation in statistical generalized phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Nobukazu; Kajihara, Kazuki

    2015-09-01

    When phase-shifting digital holography with a continuous fringe-scanning scheme is implemented using a PC-based measurement system without any synchronous circuit, nonuniform phase-shifted interference fringes are captured because of the fluctuation in the image-capturing interval. To cope with the nonuniform phase shifts, a statistical generalized phase-shifting approach is employed. Because the algorithm is designed to use an arbitrary phase shift, the nonuniform phase shifts do not obstruct object-wave retrieval. Moreover, multiple interference fringes can be obtained in a short time owing to the continuous fringe-scanning scheme. However, the wavefront calculation method is not designed for sequentially recorded interference fringes. To use multiple interference fringes appropriately, we develop a least-squares wavefront calculation method combined with corrections for the initial phase and the direction of phase rotation. We verify the proposed method by numerical simulations and optical experiments. The results show that the object wave with the same initial phase can be correctly reconstructed by using both phase correction methods simultaneously.

  3. An improved Q estimation approach: the weighted centroid frequency shift method

    NASA Astrophysics Data System (ADS)

    Li, Jingnan; Wang, Shangxu; Yang, Dengfeng; Dong, Chunhui; Tao, Yonghui; Zhou, Yatao

    2016-06-01

    Seismic wave propagation in subsurface media suffers from absorption, which can be quantified by the quality factor Q. Accurate estimation of the Q factor is of great importance for the resolution enhancement of seismic data, precise imaging and interpretation, and reservoir prediction and characterization. The centroid frequency shift method (CFS) is currently one of the most commonly used Q estimation methods. However, for seismic data that contain noise, the accuracy and stability of Q extracted using CFS depend on the choice of frequency band. In order to reduce the influence of frequency band choices and obtain Q with greater precision and robustness, we present an improved CFS Q measurement approach—the weighted CFS method (WCFS), which incorporates a Gaussian weighting coefficient into the calculation procedure of the conventional CFS. The basic idea is to enhance the proportion of advantageous frequencies in the amplitude spectrum and reduce the weight of disadvantageous frequencies. In this novel method, we first construct a Gauss function using the centroid frequency and variance of the reference wavelet. Then we employ it as the weighting coefficient for the amplitude spectrum of the original signal. Finally, the conventional CFS is adopted for the weighted amplitude spectrum to extract the Q factor. Numerical tests of noise-free synthetic data demonstrate that the WCFS is feasible and efficient, and produces more accurate results than the conventional CFS. Tests for noisy synthetic data indicate that the new method has better anti-noise capability than the CFS. The application to field vertical seismic profile (VSP) data further demonstrates its validity5.

  4. A Study of Static Shift Removal Methods in a 3D Magnetotelluric Survey at Pisagua Fault, Chile.

    NASA Astrophysics Data System (ADS)

    Bascur, J.; Comte, D.; Dias, D.; Siripunvaraporn, W.

    2014-12-01

    The static shift is one of the main problems that cause misleads in the magnetotellurics (MT) interpretation. This work presents a study comparing methods for removing the static shift effect from MT data acquired around the Pisagua Fault in Chile (2014). This evaluation considers the methods based on the joint inversion of the subsurface resistivity with the static shift effect and the calibration based on the TDEM data.First, it was developed a formulation in the data space, following the work of W. Siripunvaraporn (2005), that allows the joint inversion of the resistivity model and the static shift effect. That formulation makes it possible to use any linear representation for removing the static shift in the MT stations. This property permits compare the representation proposed by Sasaki (2004) and the static shift tensor, which use a 2x2 matrix to correct the effect. The last one is suggested to be a better model for 3D MT responses, because it can reproduce the distortion on the phase of MT data.Twenty one stations, measuring MT and TDEM methods, were acquired at the east side of the Pisagua town in the North of Chile (figure). In this place, there is an evident scarp on the topography that reveals the existence of an important fault (Pisagua Fault). Also, the Chilean desert at this location is characterized by the presence of shallow nitrate deposits (called "caliche"), whose have an elevated electrical resistance and can produce the static shift effect in the MT stations. For those reasons it was expected that the sector around the Pisagua Fault was an adequate place to evaluate static correction methods, because the data certainly would be distorted by the static shift and a successful correction method should reveal the fault observed at surface.The MT data acquired have mostly a 3D dimensionality (using A. Marti criteria, 2009) and show signs of being static shifted. A 3D inversion of this data, without considering the static shift, results in a poor

  5. DOPPLER WEATHER SYSTEM

    SciTech Connect

    Berlin, Gary J.

    2002-08-05

    The SRS Doppler Weather System consists of a Doppler Server, A Master Server (also known as the Weather Server), several Doppler Slave Servers, and client-side software program called the Doppler Radar Client. This system is used to display near rel-time images taken from the SRS Weather Center's Doppler Radar computer. The Doppler Server is software that resides on the SRS Doppler Computer. It gathers raw data, 24-bit color weather images via screen scraping ever five minutes as requested by the Master Server. The Doppler Server then reduces the 24-bit color images to 8-bit color using a fixed color table for analysis and compression. This preserves the fidelity of the image color and arranges the colors in specific order for display. At the time of color reduction, the white color used for the city names on the background images are remapped to a different index (color) of white that the white on the weather scale. The Weather Server places a time stamp on the image, then compresses the image and passes it to all Doppler Slave servers. Each of the Doppler Slave servers mainitain a circular buffer of the eight most current images representing the last 40 minutes of weather data. As a new image is added, the oldest drops off. The Doppler Radar Client is an optional install program for any site-wide workstation. When a Client session is started, the Client requests Doppler Slave server assignment from the Master Server. Upon its initial request to the Slave Server, the Client obtains all eight current images and maintains its own circular buffer, updating its images every five minutes as the Doppler Slave is updated. Three background reference images are stored as part of the Client. The Client brings up the appropriate background image, decompresses the doppler data, and displays the doppler data on the background image.

  6. DOPPLER WEATHER SYSTEM

    Energy Science and Technology Software Center (ESTSC)

    2002-08-05

    The SRS Doppler Weather System consists of a Doppler Server, A Master Server (also known as the Weather Server), several Doppler Slave Servers, and client-side software program called the Doppler Radar Client. This system is used to display near rel-time images taken from the SRS Weather Center's Doppler Radar computer. The Doppler Server is software that resides on the SRS Doppler Computer. It gathers raw data, 24-bit color weather images via screen scraping ever fivemore » minutes as requested by the Master Server. The Doppler Server then reduces the 24-bit color images to 8-bit color using a fixed color table for analysis and compression. This preserves the fidelity of the image color and arranges the colors in specific order for display. At the time of color reduction, the white color used for the city names on the background images are remapped to a different index (color) of white that the white on the weather scale. The Weather Server places a time stamp on the image, then compresses the image and passes it to all Doppler Slave servers. Each of the Doppler Slave servers mainitain a circular buffer of the eight most current images representing the last 40 minutes of weather data. As a new image is added, the oldest drops off. The Doppler Radar Client is an optional install program for any site-wide workstation. When a Client session is started, the Client requests Doppler Slave server assignment from the Master Server. Upon its initial request to the Slave Server, the Client obtains all eight current images and maintains its own circular buffer, updating its images every five minutes as the Doppler Slave is updated. Three background reference images are stored as part of the Client. The Client brings up the appropriate background image, decompresses the doppler data, and displays the doppler data on the background image.« less

  7. Phase-Shifted Based Numerical Method for Modeling Frequency-Dependent Effects on Seismic Reflections

    NASA Astrophysics Data System (ADS)

    Chen, Xuehua; Qi, Yingkai; He, Xilei; He, Zhenhua; Chen, Hui

    2016-04-01

    The significant velocity dispersion and attenuation has often been observed when seismic waves propagate in fluid-saturated porous rocks. Both the magnitude and variation features of the velocity dispersion and attenuation are frequency-dependent and related closely to the physical properties of the fluid-saturated porous rocks. To explore the effects of frequency-dependent dispersion and attenuation on the seismic responses, in this work, we present a numerical method for seismic data modeling based on the diffusive and viscous wave equation (DVWE), which introduces the poroelastic theory and takes into account diffusive and viscous attenuation in diffusive-viscous-theory. We derive a phase-shift wave extrapolation algorithm in frequencywavenumber domain for implementing the DVWE-based simulation method that can handle the simultaneous lateral variations in velocity, diffusive coefficient and viscosity. Then, we design a distributary channels model in which a hydrocarbon-saturated sand reservoir is embedded in one of the channels. Next, we calculated the synthetic seismic data to analytically and comparatively illustrate the seismic frequency-dependent behaviors related to the hydrocarbon-saturated reservoir, by employing DVWE-based and conventional acoustic wave equation (AWE) based method, respectively. The results of the synthetic seismic data delineate the intrinsic energy loss, phase delay, lower instantaneous dominant frequency and narrower bandwidth due to the frequency-dependent dispersion and attenuation when seismic wave travels through the hydrocarbon-saturated reservoir. The numerical modeling method is expected to contribute to improve the understanding of the features and mechanism of the seismic frequency-dependent effects resulted from the hydrocarbon-saturated porous rocks.

  8. Phase-Shifted Based Numerical Method for Modeling Frequency-Dependent Effects on Seismic Reflections

    NASA Astrophysics Data System (ADS)

    Chen, Xuehua; Qi, Yingkai; He, Xilei; He, Zhenhua; Chen, Hui

    2016-08-01

    The significant velocity dispersion and attenuation has often been observed when seismic waves propagate in fluid-saturated porous rocks. Both the magnitude and variation features of the velocity dispersion and attenuation are frequency-dependent and related closely to the physical properties of the fluid-saturated porous rocks. To explore the effects of frequency-dependent dispersion and attenuation on the seismic responses, in this work, we present a numerical method for seismic data modeling based on the diffusive and viscous wave equation (DVWE), which introduces the poroelastic theory and takes into account diffusive and viscous attenuation in diffusive-viscous-theory. We derive a phase-shift wave extrapolation algorithm in frequencywavenumber domain for implementing the DVWE-based simulation method that can handle the simultaneous lateral variations in velocity, diffusive coefficient and viscosity. Then, we design a distributary channels model in which a hydrocarbon-saturated sand reservoir is embedded in one of the channels. Next, we calculated the synthetic seismic data to analytically and comparatively illustrate the seismic frequency-dependent behaviors related to the hydrocarbon-saturated reservoir, by employing DVWE-based and conventional acoustic wave equation (AWE) based method, respectively. The results of the synthetic seismic data delineate the intrinsic energy loss, phase delay, lower instantaneous dominant frequency and narrower bandwidth due to the frequency-dependent dispersion and attenuation when seismic wave travels through the hydrocarbon-saturated reservoir. The numerical modeling method is expected to contribute to improve the understanding of the features and mechanism of the seismic frequency-dependent effects resulted from the hydrocarbon-saturated porous rocks.

  9. Insights on the local density approximation plasma polarization shift as provided by the optimum potential method

    SciTech Connect

    Wilson, B.; Liberman, D.A.

    1995-01-18

    The plasma polarization shift computed with a Local Density Functional model of an ion-sphere model is compared with results calculated using an optimum central field effective exchange potential. Indications are that the bulk of the shift is an artifact of the approximate exchange functional describing the interaction between bound and continuum orbitals in the LDA.

  10. Rubidium Atomic Line Filtered (RALF) Doppler Velocimetry

    NASA Astrophysics Data System (ADS)

    Fajardo, Mario; Molek, Christopher; Vesely, Annamaria; Lasem Team

    2013-06-01

    We report our progress towards adapting the well-known Global Dopper Velocimetry (GDV) technique, popular in the aerodynamics community, to the order-of-magnitude higher velocities pertinent to shock experiments. In GDV, the narrow-line illumination laser is tuned to an edge of a molecular iodine absorption line; an iodine gas cell converts the Doppler shift of the reflected light to transmitted intensity. We follow the suggestion in the original 1990 patent by Komine and broaden the absorption lines of alkali metal atoms by adding a buffer gas, thereby tuning the transmission edge spectrum to match the Doppler shift (surface velocity) range of interest. We use atomic rubidium vapor cells, with 0 to 1 atmosphere pressures of molecular nitrogen buffer gas, and coin the name ``Rubidium Atomic Line Filtered'' (RALF) Doppler velocimetry. [96ABW-2013-0036

  11. An effective phase shift diffusion equation method for analysis of PFG normal and fractional diffusions

    NASA Astrophysics Data System (ADS)

    Lin, Guoxing

    2015-10-01

    Pulsed field gradient (PFG) diffusion measurement has a lot of applications in NMR and MRI. Its analysis relies on the ability to obtain the signal attenuation expressions, which can be obtained by averaging over the accumulating phase shift distribution (APSD). However, current theoretical models are not robust or require approximations to get the APSD. Here, a new formalism, an effective phase shift diffusion (EPSD) equation method is presented to calculate the APSD directly. This is based on the idea that the gradient pulse effect on the change of the APSD can be viewed as a diffusion process in the virtual phase space (VPS). The EPSD has a diffusion coefficient, Kβ(t)D radβ/sα, where α is time derivative order and β is a space derivative order, respectively. The EPSD equations of VPS are built based on the diffusion equations of real space by replacing the diffusion coefficients and the coordinate system (from real space coordinate to virtual phase coordinate). Two different models, the fractal derivative model and the fractional derivative model from the literature were used to build the EPSD fractional diffusion equations. The APSD obtained from solving these EPSD equations were used to calculate the PFG signal attenuation. From the fractal derivative model the attenuation is exp(-γβgβδβDf1 tα), a stretched exponential function (SEF) attenuation, while from the fractional derivative model the attenuation is Eα,1(-γβgβδβDf2 tα), a Mittag-Leffler function (MLF) attenuation. The MLF attenuation can be reduced to SEF attenuation when α = 1, and can be approximated as a SEF attenuation when the attenuation is small. Additionally, the effect of finite gradient pulse widths (FGPW) is calculated. From the fractal derivative model, the signal attenuation including FGPW effect is exp[ -Df1 ∫0τ Kβ (t)dtα ] . The results obtained in this study are in good agreement with the results in literature. Several expressions that describe signal

  12. An effective phase shift diffusion equation method for analysis of PFG normal and fractional diffusions.

    PubMed

    Lin, Guoxing

    2015-10-01

    Pulsed field gradient (PFG) diffusion measurement has a lot of applications in NMR and MRI. Its analysis relies on the ability to obtain the signal attenuation expressions, which can be obtained by averaging over the accumulating phase shift distribution (APSD). However, current theoretical models are not robust or require approximations to get the APSD. Here, a new formalism, an effective phase shift diffusion (EPSD) equation method is presented to calculate the APSD directly. This is based on the idea that the gradient pulse effect on the change of the APSD can be viewed as a diffusion process in the virtual phase space (VPS). The EPSD has a diffusion coefficient, K(β)(t)D rad(β)/s(α), where α is time derivative order and β is a space derivative order, respectively. The EPSD equations of VPS are built based on the diffusion equations of real space by replacing the diffusion coefficients and the coordinate system (from real space coordinate to virtual phase coordinate). Two different models, the fractal derivative model and the fractional derivative model from the literature were used to build the EPSD fractional diffusion equations. The APSD obtained from solving these EPSD equations were used to calculate the PFG signal attenuation. From the fractal derivative model the attenuation is exp(-γ(β)g(β)δ(β)Df1t(α)), a stretched exponential function (SEF) attenuation, while from the fractional derivative model the attenuation is Eα,1(-γ(β)g(β)δ(β)Df2t(α)), a Mittag-Leffler function (MLF) attenuation. The MLF attenuation can be reduced to SEF attenuation when α=1, and can be approximated as a SEF attenuation when the attenuation is small. Additionally, the effect of finite gradient pulse widths (FGPW) is calculated. From the fractal derivative model, the signal attenuation including FGPW effect is exp[ -Df1∫0(τ) K(β)(t)dt(α)]. The results obtained in this study are in good agreement with the results in literature. Several expressions that

  13. Laser Doppler instrument measures fluid velocity without reference beam

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

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

  14. The Doppler Effect: A Consideration of Quasar Redshifts.

    ERIC Educational Resources Information Center

    Gordon, Kurtiss J.

    1980-01-01

    Provides information on the calculation of the redshift to blueshift ratio introduced by the transverse Doppler effect at relativistic speeds. Indicates that this shift should be mentioned in discussions of whether quasars are "local" rather than "cosmological" objects. (GS)

  15. Satellite Doppler data processing using a microcomputer

    NASA Technical Reports Server (NTRS)

    Schmid, P. E.; Lynn, J. J.

    1977-01-01

    A microcomputer which was developed to compute ground radio beacon position locations using satellite measurements of Doppler frequency shift is described. Both the computational algorithms and the microcomputer hardware incorporating these algorithms were discussed. Results are presented where the microcomputer in conjunction with the NIMBUS-6 random access measurement system provides real time calculation of beacon latitude and longitude.

  16. Christian Doppler and the Doppler effect

    NASA Astrophysics Data System (ADS)

    Toman, Kurt

    1984-04-01

    A summary is given of Doppler's life and career. He was born 180 years ago on November 29, 1803, in Salzburg, Austria. He died on March 17, 1853 in Venice. The effect bearing his name was first announced in a presentation before the Royal Bohemian Society of the Sciences in Prague on May 25, 1842. Doppler considered his work a generalization of the aberration theorem as discovered by Bradley. With it came the inference that the perception of physical phenomena can change with the state of motion of the observer. Acceptance of the principle was not without controversy. In 1852, the mathematician Petzval claimed that no useful scientific deductions can be made from Doppler's elementary equations. In 1860, Ernst Mach resolved the misunderstanding that clouded this controversy. The Doppler effect is alive and well. Its role in radio science and related disciplines is enumerated.

  17. Multiparametric fat–water separation method for fast chemical-shift imaging guidance of thermal therapies

    PubMed Central

    Lin, Jonathan S.; Hwang, Ken-Pin; Jackson, Edward F.; Hazle, John D.; Jason Stafford, R.; Taylor, Brian A.

    2013-01-01

    Purpose: A k-means-based classification algorithm is investigated to assess suitability for rapidly separating and classifying fat/water spectral peaks from a fast chemical shift imaging technique for magnetic resonance temperature imaging. Algorithm testing is performed in simulated mathematical phantoms and agar gel phantoms containing mixed fat/water regions. Methods: Proton resonance frequencies (PRFs), apparent spin-spin relaxation (T2*) times, and T1-weighted (T1-W) amplitude values were calculated for each voxel using a single-peak autoregressive moving average (ARMA) signal model. These parameters were then used as criteria for k-means sorting, with the results used to determine PRF ranges of each chemical species cluster for further classification. To detect the presence of secondary chemical species, spectral parameters were recalculated when needed using a two-peak ARMA signal model during the subsequent classification steps. Mathematical phantom simulations involved the modulation of signal-to-noise ratios (SNR), maximum PRF shift (MPS) values, analysis window sizes, and frequency expansion factor sizes in order to characterize the algorithm performance across a variety of conditions. In agar, images were collected on a 1.5T clinical MR scanner using acquisition parameters close to simulation, and algorithm performance was assessed by comparing classification results to manually segmented maps of the fat/water regions. Results: Performance was characterized quantitatively using the Dice Similarity Coefficient (DSC), sensitivity, and specificity. The simulated mathematical phantom experiments demonstrated good fat/water separation depending on conditions, specifically high SNR, moderate MPS value, small analysis window size, and low but nonzero frequency expansion factor size. Physical phantom results demonstrated good identification for both water (0.997 ± 0.001, 0.999 ± 0.001, and 0.986 ± 0.001 for DSC, sensitivity, and specificity, respectively

  18. Phase shift method to estimate solids circulation rate in circulating fluidized beds

    SciTech Connect

    Ludlow, James Christopher; Panday, Rupen; Shadle, Lawrence J.

    2013-01-01

    While solids circulation rate is a critical design and control parameter in circulating fluidized bed (CFB) reactor systems, there are no available techniques to measure it directly at conditions of industrial interest. Cold flow tests have been conducted at NETL in an industrial scale CFB unit where the solids flow has been the topic of research in order to develop an independent method which could be applied to CFBs operating under the erosive and corrosive high temperatures and pressures of a coal fired boiler or gasifier. The dynamic responses of the CFB loop to modest modulated aeration flows in the return leg or standpipe were imposed to establish a periodic response in the unit without causing upset in the process performance. The resulting periodic behavior could then be analyzed with a dynamic model and the average solids circulation rate could be established. This method was applied to the CFB unit operated under a wide range of operating conditions including fast fluidization, core annular flow, dilute and dense transport, and dense suspension upflow. In addition, the system was operated in both low and high total solids inventories to explore the influence of inventory limiting cases on the estimated results. The technique was able to estimate the solids circulation rate for all transport circulating fluidized beds when operating above upper transport velocity, U{sub tr2}. For CFB operating in the fast fluidized bed regime (i.e., U{sub g}< U{sub tr2}), the phase shift technique was not successful. The riser pressure drop becomes independent of the solids circulation rate and the mass flow rate out of the riser does not show modulated behavior even when the riser pressure drop does.

  19. A Rapid Method for Estimating NMR Shifts for Protons Attached to Carbon.

    ERIC Educational Resources Information Center

    Jeffreys, J. A. D.

    1979-01-01

    Presented are lists of deshielding constants chosen to be easy to remember and to given estimates close enough to measured shifts to allow interpretation of the spectrum of a compound of known structure. (BT)

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

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

  1. A simplified method for calculating the ac Stark shift of hyperfine levels of alkali-metal atoms

    NASA Astrophysics Data System (ADS)

    Xu, Xia; Qing, Bo; Chen, Xuzong; Zhou, Xiaoji

    2015-07-01

    The ac Stark shift of hyperfine levels of neutral atoms can be calculated using the third order perturbation theory (TOPT), where the third order corrections are quadratic in the atom-photon interaction and linear in the hyperfine interaction. In this paper, we use Green's function to derive the E [ 2 + ɛ ] method which can give close values to those of TOPT for the differential light shift between two hyperfine levels. It comes with a simple form and easy incorporation of theoretical and experimental atomic structure data. Furthermore, we analyze the order of approximation and give the condition under which E [ 2 + ɛ ] method is valid.

  2. Rotational Doppler Effect and Barnett Field in Spinning NMR

    NASA Astrophysics Data System (ADS)

    Chudo, Hiroyuki; Harii, Kazuya; Matsuo, Mamoru; Ieda, Jun'ichi; Ono, Masao; Maekawa, Sadamichi; Saitoh, Eiji

    2015-04-01

    We report the observation of the rotational Doppler effect using nuclear magnetic resonance (NMR). We have developed a coil-spinning technique that enables measurements by rotating a detector and fixing a sample. We found that the rotational Doppler effect gives rise to NMR frequency shifts equal to the rotation frequency. We formulate the rotational Doppler effect and the Barnett field using a vector model for the nuclear magnetic moment. This formulation reveals that, with just the sample rotating, both effects cancel each other, thereby explaining the absence of an NMR frequency shift in conventional sample-spinning NMR measurements.

  3. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    PubMed

    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

  4. Methods to recover the narrow Dicke sub-Doppler feature in evacuated wall-coated cells without restrictions on cell size

    NASA Technical Reports Server (NTRS)

    Robinson, H. G.

    1984-01-01

    The hyperfine resonance observed in evacuated wall-coated cells with dimensions lambda/2 (lambda is the hyperfine resonance wavelength) consists of a narrow Dicke sub-Doppler linewidth feature, the spike, superimposed on a broad pedestal. The hydrogen maser provides a classic example of this lineshape. As cell size is increased, an effect unique to evacuated wall-coated cells occurs. Certain combinations of microwave field distribution and cell size result in a lineshape having a pedestal with a small spike feature or only the broad pedestal with no spike. Such conditions are not appropriate for atomic frequency standard applications. The cause of the evacuated wall-coated cell lineshape is reviewed and methods to recover the narrow spike feature without restrictions on cell size is discussed. One example is a cell with dimensions having equal volumes of exposure to opposite phases of the microwave magnetic field.

  5. Red Shifts with Obliquely Approaching Light Sources.

    ERIC Educational Resources Information Center

    Head, C. E.; Moore-Head, M. E.

    1988-01-01

    Refutes the Doppler effect as the explanation of large red shifts in the spectra of distant galaxies and explains the relativistic effects in which the light sources approach the observer obliquely. Provides several diagrams and graphs. (YP)

  6. Iodine-filter-based mobile Doppler lidar to make continuous and full-azimuth-scanned wind measurements: data acquisition and analysis system, data retrieval methods, and error analysis.

    PubMed

    Wang, Zhangjun; Liu, Zhishen; Liu, Liping; Wu, Songhua; Liu, Bingyi; Li, Zhigang; Chu, Xinzhao

    2010-12-20

    An incoherent Doppler wind lidar based on iodine edge filters has been developed at the Ocean University of China for remote measurements of atmospheric wind fields. The lidar is compact enough to fit in a minivan for mobile deployment. With its sophisticated and user-friendly data acquisition and analysis system (DAAS), this lidar has made a variety of line-of-sight (LOS) wind measurements in different operational modes. Through carefully developed data retrieval procedures, various wind products are provided by the lidar, including wind profile, LOS wind velocities in plan position indicator (PPI) and range height indicator (RHI) modes, and sea surface wind. Data are processed and displayed in real time, and continuous wind measurements have been demonstrated for as many as 16 days. Full-azimuth-scanned wind measurements in PPI mode and full-elevation-scanned wind measurements in RHI mode have been achieved with this lidar. The detection range of LOS wind velocity PPI and RHI reaches 8-10 km at night and 6-8 km during daytime with range resolution of 10 m and temporal resolution of 3 min. In this paper, we introduce the DAAS architecture and describe the data retrieval methods for various operation modes. We present the measurement procedures and results of LOS wind velocities in PPI and RHI scans along with wind profiles obtained by Doppler beam swing. The sea surface wind measured for the sailing competition during the 2008 Beijing Olympics is also presented. The precision and accuracy of wind measurements are estimated through analysis of the random errors associated with photon noise and the systematic errors introduced by the assumptions made in data retrieval. The three assumptions of horizontal homogeneity of atmosphere, close-to-zero vertical wind, and uniform sensitivity are made in order to experimentally determine the zero wind ratio and the measurement sensitivity, which are important factors in LOS wind retrieval. Deviations may occur under certain

  7. Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging.

    PubMed

    Ju, Myeong Jin; Hong, Young-Joo; Makita, Shuichi; Lim, Yiheng; Kurokawa, Kazuhiro; Duan, Lian; Miura, Masahiro; Tang, Shuo; Yasuno, Yoshiaki

    2013-08-12

    An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced JMT achieves a sufficiently long depth measurement range for clinical cases of posterior eye disease. Furthermore, a fine spectral shift compensation method based on the cross-correlation of calibration signals was devised for stabilizing the phase of OCT, which enables a high sensitivity Doppler OCT measurement. In addition, a new theory of JMT which integrates the Jones matrix measurement, Doppler measurement, and scattering measurement is presented. This theory enables a sensitivity-enhanced scattering OCT and high-sensitivity Doppler OCT. These new features enable the application of this system to clinical cases. A healthy subject and a geographic atrophy patient were measured in vivo, and simultaneous imaging of choroidal vasculature and birefringence structures are demonstrated. PMID:23938857

  8. Complex surface three-dimensional shape measurement method based on defocused Gray code plus phase-shifting

    NASA Astrophysics Data System (ADS)

    Zeng, Zhuohuan; Fu, Yanjun; Li, Biao; Chai, Minggang

    2016-08-01

    Binary pattern defocused projection method can overcome the nonlinear gamma of the projector, as well as filter high harmonics and high-frequency noise. However, high-accuracy three-dimensional (3-D) shape measurement of complex surface using it still remains a challenge. Therefore, a novel Gray code plus phase-shifting method based on defocusing is proposed to solve the problem. The edges of Gray code patterns become blurred owing to defocus, which makes the recovery of accurate Gray code patterns difficult. To solve this problem, the positive and inverse Gray code patterns are projected to obtain threshold values, which are used to achieve the binarization of Gray code patterns. This method is robust and suitable for different defocus levels. Compared with the traditional Gray code plus phase-shifting method, the experimental results prove the effectiveness and feasibility of the proposed method.

  9. Ground-Based Rayleigh-Mie Doppler Lidar for Wind Measurements in the Middle Atmosphere

    NASA Astrophysics Data System (ADS)

    Khaykin, S. M.; Hauchecorne, A.; Porteneuve, J.; Mariscal, J.-F.; D'Almeida, E.; Cammas, J.-P.; Payen, G.; Evan, S.; Keckhut, P.

    2016-06-01

    A unique Rayleigh-Mie Doppler wind lidar, measuring Doppler shift between the emitted and backscattered light using directdetection technique is deployed at Observatory of Haute Provence Southern France) and at Reunion island (tropical Indian Ocean). The instrument was shown capable of wind measurements between 5 and 50 km with accuracy better than 1 m/s up to 30 km. The system consists of a monomode Nd:Yag laser operating at 532 nm, three telescopes and a double-edge Fabry-Perot interferometer. The laser light is sent alternatively in the vertical as well as zonal and meridional directions at 40° from the zenith using a rotating mirror. The two components of the horizontal wind are obtained from the measurement of the Doppler shift of the return signal spectrally filtered by the Fabry-Perot etalon. After demonstration of the method in 1989 the measurements were used for studying stratospheric dynamics as well as for constructing wind climatology up to 50 km altitude. A new system, featuring a more compact design was installed at Maïdo observatory at Reunion Island (21° S). The design of the instrument, results of observations and comparison against GPS radiosondes are presented. Application of Doppler lidar for validation of the future ADM-Aeolus satellite mission is discussed as well.

  10. Analysis and compensation for code Doppler effect of BDS II signal under high dynamics

    NASA Astrophysics Data System (ADS)

    Ouyang, Xiaofeng; Zeng, Fangling

    2016-01-01

    In high dynamic circumstances, the acquisition of BDS (BeiDou Navigation Satellite System) signal would be affected by the pseudo-code Doppler. The pseudo-code frequency shift is more prominent and complex when BOC modulation has been adopted by BDS-II, but is not yet involved in current compensation algorithm. In addition, the most frequently used code Doppler compensation algorithm is modifying the sampling rate or local bit rate, which not only increases the complexity of the acquisition and tracking, but also is barely realizable for the hardware receiver to modify the local frequency. Therefore, this paper proposes a code Doppler compensation method based on double estimator receiver, which simultaneously controls NCO delay of code tracking loop and subcarrier tracking loop to compensate for pseudo-code frequency shift. The simulation and test are implemented with BDS-II BOC signal. The test results demonstrate that the proposed algorithm can effectively compensate for pseudo-code Doppler of BOC signal and has detection probability 3dB higher than the uncompensated situation when the false alarm rate is under 0.01 and the coherent integration time is 1ms.

  11. Design of a tri-monostatic doppler sodar system

    NASA Astrophysics Data System (ADS)

    Ito, Yoshiki

    This paper outlined the general purpose Doppler sodar AR410. Together with the acoustic antenna design and the circuit function, the present author suggested the signal processing technique to estimate the Doppler frequency shift based on the FFT method and the way to reject unavailable signals. It may be helpful to refer to the nomogram to estimate the maximum altitude of acoustic sounding. Some results on the wind data compared with in situ measurements show the reliability of the Doppler sodar. The correlation coefficient of wind speed is better than 0.9, and the standard deviation of the difference of wind speed and wind direction is 0.7 to 2.3 m/s and 10 to 35 deg respectively dependent on wind speed. The sodar system helps the meteorological observation of the lower atmospheric boundary layer. It gives wind profile up to several hundred meters with the condition in which the annual data loss rate is less than 2% at the height of 100 m and is less than 10% at 200 m. Saying about turbulent parameters, w seems to be the available function, whereas u and v are under development to make a better estimation. The detection of temperature inversion and qualitative monitoring of thermal structure from echo intensity is reliably carried out, but the quantitative analysis with sufficient accuracy such as the temperature fluctuation or the temperature lapse remains as future works.

  12. Potential energy function information from quantum phase shift using the variable phase method.

    PubMed

    Lemes, Nelson H T; Braga, João P; Alves, Márcio O; Costa, Éderson D'M

    2014-07-01

    The present work discusses quantum phase shift sensitivity analysis with respect to the potential energy function. A set of differential equations for the functional derivative of the quantum phase shift with respect to the potential energy function was established and coupled with the variable phase equation. This set of differential equations provides a simple, exact and straightforward way to establish the sensitivity matrix. The present procedure is easier to use than the finite difference approach, in which several direct problems have to be addressed. Furthermore, integration of the established equations can be used to demonstrate how the sensitivity phase shift is accumulated as a function of the interatomic distance. The potential energy function was refined to produce a better quality function. The average error on the phase shift decreased from 9.8% in the original potential function to 0.13% in the recovered potential. The present procedure is an important initial step for further work towards recovering potential energy functions in upper dimensions or to recovering this function from cross sections. PMID:24935112

  13. Shift-invariant, DWT-based "projection" method for estimation of ultrasound pulse power spectrum.

    PubMed

    Michailovich, Oleg; Adam, Dan

    2002-08-01

    An approach to computing estimates of the ultrasound pulse spectrum from echo-ultrasound RF sequences, measured from biological tissues, is proposed. It is computed by a "projection" algorithm based on the Discrete Wavelet Transform (DWT) using averaging over a range of linear shifts. It is shown that the robust, shift invariant estimate of the ultrasound pulse power spectrum can be obtained by the projection of RF line log spectrum on an appropriately chosen subspace of L2(R) (i.e., the space of square-integrable functions) that is spanned by a redundant collection of compactly supported, scaling functions. This redundant set is formed from the traditional (in Wavelet analysis) orthogonal set of scaling functions and also by all its linear (discrete) shifts. A proof is given that the estimate, so obtained, could be viewed as the average of the orthogonal projections of the RF line log spectrum, computed for all significant linear shifts of the RF line log spectrum in frequency domain. It implies that the estimate is shift-invariant. A computationally efficient scheme is presented for calculating the estimate. Proof is given that the averaged, shift-invariant estimate can be obtained simply by a convolution with a kernel, which can be viewed as the discretized auto-correlation function of the scaling function, appropriate to the particular subspace being considered. It implies that the computational burden is at most O(n log2 n), where n is the problem size, making the estimate quite suitable for real-time processing. Because of the property of the wavelet transform to suppress polynomials of orders lower than the number of the vanishing moments of the wavelet used, the presented approach can be considered as a local polynomial fitting. This locality plays a crucial role in the performance of the algorithm, improving the robustness of the estimation. Moreover, it is shown that the "averaging" nature of the proposed estimation allows using (relatively) poorly

  14. Relationship of spaced antenna and Doppler techniques for velocity measurements (keynote paper), part 3

    NASA Technical Reports Server (NTRS)

    Vincent, R. A.

    1984-01-01

    The Doppler, spaced-antenna and interferometric methods of measuring wind velocities all use the same basic information, the Doppler shifts imposed on backscattered radio waves, but they process it in different ways. The Doppler technique is most commonly used at VHF since the narrow radar beams are readily available. However, the spaced antenna (SA) method has been successfully used with the SOUSY and Adelaide radars. At MF/HF the spaced antenna method is widely used since the large antenna arrays (diameter 1 km) required to generate narrow beams are expensive to construct. Where such arrays of this size are available then the Doppler method has been successfully used (e.g., Adelaide and Brisbane). In principle, the factors which influence the choice of beam pointing angle, the optimum antenna spacing will be the same whether operation is at MF or VHF. Many of the parameters which govern the efficient use of wind measuring systems have been discussed at previous MST workshops. Some of the points raised by these workshops are summarized.

  15. Nuclear magnetic resonance shielding constants and chemical shifts in linear 199Hg compounds: A comparison of three relativistic computational methods

    NASA Astrophysics Data System (ADS)

    Arcisauskaite, Vaida; Melo, Juan I.; Hemmingsen, Lars; Sauer, Stephan P. A.

    2011-07-01

    We investigate the importance of relativistic effects on NMR shielding constants and chemical shifts of linear HgL2 (L = Cl, Br, I, CH3) compounds using three different relativistic methods: the fully relativistic four-component approach and the two-component approximations, linear response elimination of small component (LR-ESC) and zeroth-order regular approximation (ZORA). LR-ESC reproduces successfully the four-component results for the C shielding constant in Hg(CH3)2 within 6 ppm, but fails to reproduce the Hg shielding constants and chemical shifts. The latter is mainly due to an underestimation of the change in spin-orbit contribution. Even though ZORA underestimates the absolute Hg NMR shielding constants by ˜2100 ppm, the differences between Hg chemical shift values obtained using ZORA and the four-component approach without spin-density contribution to the exchange-correlation (XC) kernel are less than 60 ppm for all compounds using three different functionals, BP86, B3LYP, and PBE0. However, larger deviations (up to 366 ppm) occur for Hg chemical shifts in HgBr2 and HgI2 when ZORA results are compared with four-component calculations with non-collinear spin-density contribution to the XC kernel. For the ZORA calculations it is necessary to use large basis sets (QZ4P) and the TZ2P basis set may give errors of ˜500 ppm for the Hg chemical shifts, despite deceivingly good agreement with experimental data. A Gaussian nucleus model for the Coulomb potential reduces the Hg shielding constants by ˜100-500 ppm and the Hg chemical shifts by 1-143 ppm compared to the point nucleus model depending on the atomic number Z of the coordinating atom and the level of theory. The effect on the shielding constants of the lighter nuclei (C, Cl, Br, I) is, however, negligible.

  16. Nuclear magnetic resonance shielding constants and chemical shifts in linear 199Hg compounds: a comparison of three relativistic computational methods.

    PubMed

    Arcisauskaite, Vaida; Melo, Juan I; Hemmingsen, Lars; Sauer, Stephan P A

    2011-07-28

    We investigate the importance of relativistic effects on NMR shielding constants and chemical shifts of linear HgL(2) (L = Cl, Br, I, CH(3)) compounds using three different relativistic methods: the fully relativistic four-component approach and the two-component approximations, linear response elimination of small component (LR-ESC) and zeroth-order regular approximation (ZORA). LR-ESC reproduces successfully the four-component results for the C shielding constant in Hg(CH(3))(2) within 6 ppm, but fails to reproduce the Hg shielding constants and chemical shifts. The latter is mainly due to an underestimation of the change in spin-orbit contribution. Even though ZORA underestimates the absolute Hg NMR shielding constants by ∼2100 ppm, the differences between Hg chemical shift values obtained using ZORA and the four-component approach without spin-density contribution to the exchange-correlation (XC) kernel are less than 60 ppm for all compounds using three different functionals, BP86, B3LYP, and PBE0. However, larger deviations (up to 366 ppm) occur for Hg chemical shifts in HgBr(2) and HgI(2) when ZORA results are compared with four-component calculations with non-collinear spin-density contribution to the XC kernel. For the ZORA calculations it is necessary to use large basis sets (QZ4P) and the TZ2P basis set may give errors of ∼500 ppm for the Hg chemical shifts, despite deceivingly good agreement with experimental data. A Gaussian nucleus model for the Coulomb potential reduces the Hg shielding constants by ∼100-500 ppm and the Hg chemical shifts by 1-143 ppm compared to the point nucleus model depending on the atomic number Z of the coordinating atom and the level of theory. The effect on the shielding constants of the lighter nuclei (C, Cl, Br, I) is, however, negligible. PMID:21806118

  17. Modified cavity attenuated phase shift (CAPS) method for airborne aerosol light extinction measurement

    NASA Astrophysics Data System (ADS)

    Perim de Faria, Julia; Bundke, Ulrich; Freedman, Andrew; Petzold, Andreas

    2015-04-01

    Monitoring the direct impact of aerosol particles on climate requires the consideration of at least two major factors: the aerosol single-scattering albedo, defined as the relation between the amount of energy scattered and extinguished by an ensemble of aerosol particles; and the aerosol optical depth, calculated from the integral of the particle extinction coefficient over the thickness of the measured aerosol layer. Remote sensing networks for measuring these aerosol parameters on a regular basis are well in place (e.g., AERONET, ACTRIS), whereas the regular in situ measurement of vertical profiles of atmospheric aerosol optical properties remains still an important challenge in quantifying climate change. The European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; www.iagos.org) responds to the increasing requests for long-term, routine in situ observational data by using commercial passenger aircraft as measurement platform. However, scientific instrumentation for the measurement of atmospheric constituents requires major modifications before being deployable aboard in-service passenger aircraft. Recently, a compact and robust family of optical instruments based on the cavity attenuated phase shift (CAPS) technique has become available for measuring aerosol light extinction. In particular, the CAPS PMex particle optical extinction monitor has demonstrated sensitivity of less than 2 Mm-1 in 1 second sampling period; with a 60 s averaging time, a detection limit of less than 0.3 Mm-1 can be achieved. While this technique was successfully deployed for ground-based atmospheric measurements under various conditions, its suitability for operation aboard aircraft in the free and upper free troposphere still has to be demonstrated. Here, we report on the modifications of a CAPS PMex instrument for measuring aerosol light extinction on aircraft, and subsequent laboratory tests for evaluating the modified instrument prototype: (1) In a

  18. Fluid Shifts

    NASA Technical Reports Server (NTRS)

    Stenger, M. B.; Hargens, A.; Dulchavsky, S.; Ebert, D.; Lee, S.; Laurie, S.; Garcia, K.; Sargsyan, A.; Martin, D.; Lui, J.; Macias, B.; Arbeille, P.; Danielson, R.; Chang, D.; Gunga, H.; Johnston, S.; Westby, C.; Ribeiro, L.; Ploutz-Snyder, R.; Smith, S.

    2015-01-01

    INTRODUCTION: Mechanisms responsible for the ocular structural and functional changes that characterize the visual impairment and intracranial pressure (ICP) syndrome (VIIP) are unclear, but hypothesized to be secondary to the cephalad fluid shift experienced in spaceflight. This study will relate the fluid distribution and compartmentalization associated with long-duration spaceflight with VIIP symptoms. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as the VIIP-related effects of those shifts, can be predicted preflight with acute hemodynamic manipulations, and also if lower body negative pressure (LBNP) can reverse the VIIP effects. METHODS: Physiologic variables will be examined pre-, in- and post-flight in 10 International Space Station crewmembers including: fluid compartmentalization (D2O and NaBr dilution); interstitial tissue thickness (ultrasound); vascular dimensions and dynamics (ultrasound and MRI (including cerebrospinal fluid pulsatility)); ocular measures (optical coherence tomography, intraocular pressure, ultrasound); and ICP measures (tympanic membrane displacement, otoacoustic emissions). Pre- and post-flight measures will be assessed while upright, supine and during 15 deg head-down tilt (HDT). In-flight measures will occur early and late during 6 or 12 month missions. LBNP will be evaluated as a countermeasure during HDT and during spaceflight. RESULTS: The first two crewmembers are in the preflight testing phase. Preliminary results characterize the acute fluid shifts experienced from upright, to supine and HDT postures (increased stroke volume, jugular dimensions and measures of ICP) which are reversed with 25 millimeters Hg LBNP. DISCUSSION: Initial results indicate that acute cephalad fluid shifts may be related to VIIP symptoms, but also may be reversible by LBNP. The effect of a chronic fluid shift has yet to be evaluated. Learning Objectives: Current spaceflight VIIP research is described

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

    NASA Astrophysics Data System (ADS)

    Adair, Henry S., III

    1998-07-01

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

  20. A Novel Compressed Sensing Method for Magnetic Resonance Imaging: Exponential Wavelet Iterative Shrinkage-Thresholding Algorithm with Random Shift.

    PubMed

    Zhang, Yudong; Yang, Jiquan; Yang, Jianfei; Liu, Aijun; Sun, Ping

    2016-01-01

    Aim. It can help improve the hospital throughput to accelerate magnetic resonance imaging (MRI) scanning. Patients will benefit from less waiting time. Task. In the last decade, various rapid MRI techniques on the basis of compressed sensing (CS) were proposed. However, both computation time and reconstruction quality of traditional CS-MRI did not meet the requirement of clinical use. Method. In this study, a novel method was proposed with the name of exponential wavelet iterative shrinkage-thresholding algorithm with random shift (abbreviated as EWISTARS). It is composed of three successful components: (i) exponential wavelet transform, (ii) iterative shrinkage-thresholding algorithm, and (iii) random shift. Results. Experimental results validated that, compared to state-of-the-art approaches, EWISTARS obtained the least mean absolute error, the least mean-squared error, and the highest peak signal-to-noise ratio. Conclusion. EWISTARS is superior to state-of-the-art approaches. PMID:27066068

  1. Novel Scheme of Carrier Tri-reuse and Distribution Fiber Protection Based on Round Shift Method in Optical Access Network

    NASA Astrophysics Data System (ADS)

    Chen, Haibin; Gan, Chaoqin; Yin, Maojun; Ni, Cuiping

    2015-06-01

    A novel architecture of optical access network based on round shift method is proposed. Round shift method is composed by round service mode of carriers and cycle characteristic of 2×N arrayed waveguide grating (AWG). By utilizing the round service mode, every carrier is tri-reused to provide service for three different optical network units. Besides, in remote node, the 2×3N AWG can be replaced by three 2×N AWGs and AWGs' channel spacing is increased. So, the demand on RN's AWGs is decreased. Furthermore, based on the cycle characteristic of 2×N AWG, a 1+1 protection scheme is presented to provide independent protection for distribution fibers. Simulation and analysis show the proposed scheme works well.

  2. A Novel Compressed Sensing Method for Magnetic Resonance Imaging: Exponential Wavelet Iterative Shrinkage-Thresholding Algorithm with Random Shift

    PubMed Central

    Zhang, Yudong; Yang, Jiquan; Yang, Jianfei; Liu, Aijun; Sun, Ping

    2016-01-01

    Aim. It can help improve the hospital throughput to accelerate magnetic resonance imaging (MRI) scanning. Patients will benefit from less waiting time. Task. In the last decade, various rapid MRI techniques on the basis of compressed sensing (CS) were proposed. However, both computation time and reconstruction quality of traditional CS-MRI did not meet the requirement of clinical use. Method. In this study, a novel method was proposed with the name of exponential wavelet iterative shrinkage-thresholding algorithm with random shift (abbreviated as EWISTARS). It is composed of three successful components: (i) exponential wavelet transform, (ii) iterative shrinkage-thresholding algorithm, and (iii) random shift. Results. Experimental results validated that, compared to state-of-the-art approaches, EWISTARS obtained the least mean absolute error, the least mean-squared error, and the highest peak signal-to-noise ratio. Conclusion. EWISTARS is superior to state-of-the-art approaches. PMID:27066068

  3. Averaging methods for the phase shift of arbitrarily perturbed strongly nonlinear oscillators with an application to capture

    NASA Astrophysics Data System (ADS)

    Bourland, F. J.; Haberman, Richard; Kath, William L.

    1991-08-01

    Strongly nonlinear oscillators under slowly varying perturbations (not necessarily Hamiltonian) are analyzed by putting the equations into the standard form for the method of averaging. By using the usual near-identity transformations, energy-angle (and equivalent action-angle) equations are derived using the properties of strongly nonlinear oscillators. By introducing a perturbation expansion, a differential equation for the phase shift is derived and shown to agree with earlier results obtained by Bourland and Haberman using the multiple scale perturbation method. The slowly varying phase shift is used (by necessity) to determine the boundary of the basin of attraction for competing stable equilibria, even though these averaged equations are known not to be valid near a separatrix (unperturbed homoclinic orbit).

  4. Tuning the pH-shift protein-isolation method for maximum hemoglobin-removal from blood rich fish muscle.

    PubMed

    Abdollahi, Mehdi; Marmon, Sofia; Chaijan, Manat; Undeland, Ingrid

    2016-12-01

    A main challenge preventing optimal use of protein isolated from unconventional raw materials (e.g., small pelagic fish and fish by-products) using the pH-shift method is the difficulty to remove enough heme-pigments. Here, the distribution of hemoglobin (Hb) in the different fractions formed during pH-shift processing was studied using Hb-fortified cod mince. Process modifications, additives and prewashing were then investigated to further facilitate Hb-removal. The alkaline pH-shift process version could remove considerably more Hb (77%) compared to the acidic version (37%) when proteins were precipitated at pH 5.5; most Hb was removed during dewatering. Protein precipitation at pH 6.5 improved total Hb removal up to 91% and 74% during alkaline and acid processing, respectively. Adding phytic acid to the first supernatant of the alkaline process version yielded 93% Hb removal. Combining one prewash with phytic acid at pH 5.5 followed by alkaline/acid pH-shift processing increased Hb removal up to 96/92%. PMID:27374526

  5. The leicester Doppler phantom--a digital electronic phantom for ultrasound pulsed Doppler system testing.

    PubMed

    Gittins, John; Martin, Kevin

    2010-04-01

    Doppler flow and string phantoms have been used to assess the performance of ultrasound Doppler systems in terms of parameters such as sensitivity, velocity accuracy and sample volume registration. However, because of the nature of their construction, they cannot challenge the accuracy and repeatability of modern digital ultrasound systems or give objective measures of system performance. Electronic Doppler phantoms are able to make use of electronically generated test signals, which may be controlled precisely in terms of frequency, amplitude and timing. The Leicester Electronic Doppler Phantom uses modern digital signal processing methods and field programmable gate array technology to overcome some of the limitations of previously described electronic phantoms. In its present form, it is able to give quantitative graphical assessments of frequency response and range gate characteristics, as well as measures of dynamic range and velocity measurement accuracy. The use of direct acoustic coupling eliminates uncertainties caused by Doppler beam effects, such as intrinsic spectral broadening, but prevents their evaluation. PMID:20350689

  6. Validation of method for enhanced production of red-shifted bioluminescent photons in vivo

    NASA Astrophysics Data System (ADS)

    Dragavon, Joe; Blazquez, Samantha; Rogers, Kelly L.; Samson, Chelsea; Tournebize, Régis; Shorte, Spencer

    2011-02-01

    Bioluminescence Imaging (BLI) is an increasingly useful and applicable technique that allows for the non-invasive observation of biological events in intact living organisms, ranging from single cells to small rodents. Though the photon production occurs within the host, significant exposure times can be necessary due to the low photon flux compared to fluorescence imaging. The optical absorption spectrum of haemoglobin strongly overlaps most bioluminescent emission spectra, greatly attenuating the total detectable photons in animal models. We have developed and validated a technique that is able to red-shift the bioluminescent photons to the more desirable optical region of > 650 nm, a region of minimal absorbance by hemoglobin. This red-shift occurs by using bioluminescence as an internal light source capable of exciting a fluorophore, such as a fluorescent protein or a quantum dot, that emits in the red. Interestingly, in the absence of an absorber, this excitation can occur over substantial distances (microns to centimeters), far exceeding distances associated to, and thereby precluding, resonance energy transfer phenomena. We show this novel technique yields a substantial increase in the number of red photons for in vitro and ex vivo conditions, suggesting eventually utility for in vivo studies on, for example, intact living mice.

  7. Determination of the misalignment error of a compound zero-order waveplate using the spectroscopic phase shifting method

    NASA Astrophysics Data System (ADS)

    Zheng, Quan; Han, Zhigang; Chen, Lei

    2016-09-01

    The spectroscopic phase shifting method was proposed to determine the misalignment error of a compound zero-order waveplate. The waveplate, which is composed of two separate multi-order quartz waveplates, was measured by a polarizer-waveplate-analyser setup with a spectrometer as the detector. The theoretical relationship between the misalignment error and the azimuth of the polarized light that emerged from the waveplate was studied by comparing two forms of the Jones matrix of the waveplate. Four spectra were obtained to determine the wavelength-dependent azimuth using a phase shifting algorithm when the waveplate was rotated to four detection angles. The misalignment error was ultimately solved from the wavelength-dependent azimuth by the Levenberg-Marquardt method. Experiments were conducted at six misalignment angles. The measured results of the misalignment angle agree well with their nominal values, indicating that the spectroscopic phase shifting method can be a reliable way to measure the misalignment error of a compound zero-order waveplate.

  8. Mechanism Analysis of the Inverse Doppler Effect in Two-Dimensional Photonic Crystal based on Phase Evolution.

    PubMed

    Jiang, Qiang; Chen, Jiabi; Wang, Yan; Liang, Binming; Hu, Jinbing; Zhuang, Songlin

    2016-01-01

    Although the inverse Doppler effect has been observed experimentally at optical frequencies in photonic crystal with negative effective refractive index, its explanation is based on phenomenological theory rather than a strict theory. Elucidating the physical mechanism underlying the inverse Doppler shift is necessary. In this article, the primary electrical field component in the photonic crystal that leads to negative refraction was extracted, and the phase evolution of the entire process when light travels through a moving photonic crystal was investigated using static and dynamic finite different time domain methods. The analysis demonstrates the validity of the use of np (the effective refractive index of the photonic crystal in the light path) in these calculations, and reveals the origin of the inverse Doppler effect in photonic crystals. PMID:27102211

  9. Mechanism Analysis of the Inverse Doppler Effect in Two-Dimensional Photonic Crystal based on Phase Evolution

    NASA Astrophysics Data System (ADS)

    Jiang, Qiang; Chen, Jiabi; Wang, Yan; Liang, Binming; Hu, Jinbing; Zhuang, Songlin

    2016-04-01

    Although the inverse Doppler effect has been observed experimentally at optical frequencies in photonic crystal with negative effective refractive index, its explanation is based on phenomenological theory rather than a strict theory. Elucidating the physical mechanism underlying the inverse Doppler shift is necessary. In this article, the primary electrical field component in the photonic crystal that leads to negative refraction was extracted, and the phase evolution of the entire process when light travels through a moving photonic crystal was investigated using static and dynamic finite different time domain methods. The analysis demonstrates the validity of the use of np (the effective refractive index of the photonic crystal in the light path) in these calculations, and reveals the origin of the inverse Doppler effect in photonic crystals.

  10. Mechanism Analysis of the Inverse Doppler Effect in Two-Dimensional Photonic Crystal based on Phase Evolution

    PubMed Central

    Jiang, Qiang; Chen, Jiabi; Wang, Yan; Liang, Binming; Hu, Jinbing; Zhuang, Songlin

    2016-01-01

    Although the inverse Doppler effect has been observed experimentally at optical frequencies in photonic crystal with negative effective refractive index, its explanation is based on phenomenological theory rather than a strict theory. Elucidating the physical mechanism underlying the inverse Doppler shift is necessary. In this article, the primary electrical field component in the photonic crystal that leads to negative refraction was extracted, and the phase evolution of the entire process when light travels through a moving photonic crystal was investigated using static and dynamic finite different time domain methods. The analysis demonstrates the validity of the use of np (the effective refractive index of the photonic crystal in the light path) in these calculations, and reveals the origin of the inverse Doppler effect in photonic crystals. PMID:27102211

  11. Rotational Doppler effect in x-ray photoionization

    SciTech Connect

    Sun Yuping; Wang Chuankui; Gel'mukhanov, Faris

    2010-11-15

    The energy of the photoelectron experiences a red or blue Doppler shift when the molecule recedes from the detector or approaches him. This results in a broadening of the photoelectron line due to the translational thermal motion. However, the molecules also have rotational degrees of freedom and we show that the translational Doppler effect has its rotational counterpart. This rotational Doppler effect leads to an additional broadening of the spectral line of the same magnitude as the Doppler broadening caused by translational thermal motion. The rotational Doppler broadening as well as the rotational recoil broadening is sensitive to the molecular orbital from which the photoelectron is ejected. This broadening should be taken into account in analysis of x-ray photoemission spectra of super-high resolution and it can be directly observed using x-ray pump-probe spectroscopy.

  12. Doppler-cancelled response to VLF gravitational waves

    NASA Technical Reports Server (NTRS)

    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.

  13. The joint estimation of differential delay, Doppler, and phase

    NASA Astrophysics Data System (ADS)

    Wax, M.

    1982-09-01

    In radio and sonar applications it sometimes happens that narrow-band signals, originated from a remote source and observed at a pair of receivers, differ by unknown differential phase and Doppler shift in addition to the differential delay corresponding to the range difference. The correspondence presents the joint maximum likelihood (ML) estimate of the differential delay, Doppler, and phase and examines their accuracy by deriving the Cramer-Rao bound. It is shown that joint ML estimators are the values of the delay and Doppler that maximize the magnitude of a generalized ambiguity function analogous to the one used in radar. It is also shown that for long observation time and high enough signal-to-noise ratio there is no degradation in the accuracy of the time-delay estimator due to the additional phase and Doppler uncertainty and that the differential Doppler is uncorrelated with the differential delay and phase estimators.

  14. Color Doppler flow imaging.

    PubMed

    Foley, W D; Erickson, S J

    1991-01-01

    The performance requirements and operational parameters of a color Doppler system are outlined. The ability of an operator to recognize normal and abnormal variations in physiologic flow and artifacts caused by noise and aliasing is emphasized. The use of color Doppler flow imaging is described for the vessels of the neck and extremities, upper abdomen and abdominal transplants, obstetrics and gynecology, dialysis fistulas, and testicular and penile flow imaging. PMID:1898567

  15. Electromagnetic scattering and Doppler spectrum simulation of time-varying oil-covered nonlinear sea surface

    NASA Astrophysics Data System (ADS)

    Yang, Pengju; Guo, Lixin; Jia, Chungang

    2016-01-01

    Based on the model of Lombardini et al. [J. Atmos. Ocean. Technol. 6(6), 882-890 (1989)], which can predict the hydrodynamic damping of rough sea surfaces in the presence of oil films, the influence of sea slicks on the sea surface roughness spectrum and sea surface geometrical structure is examined briefly in the present study. On this basis, the influence of sea slicks on the angular distribution of the bistatic scattering coefficient of sea surfaces and the Doppler spectrum signature of backscattered radar sea-echo is investigated in detail based on a frequency-domain numerical method of the parallel fast multiple method. Simulation results show that Doppler spectrum signatures including Doppler shift and spectral bandwidth of radar sea-echo are significantly affected by sea slicks, which are qualitatively consistent with wave-tank or open sea measurements. Moreover, simulation results indicate that the Doppler spectrum signature is a promising technique for remote sensing of oil films floating on sea surfaces.

  16. Advances in Direct Detection Doppler Lidar Technology and Techniques

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce; Einaudi, Franco (Technical Monitor)

    2001-01-01

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

  17. Computer vision approach for ultrasound Doppler angle estimation.

    PubMed

    Saad, Ashraf A; Loupas, Thanasis; Shapiro, Linda G

    2009-12-01

    Doppler ultrasound is an important noninvasive diagnostic tool for cardiovascular diseases. Modern ultrasound imaging systems utilize spectral Doppler techniques for quantitative evaluation of blood flow velocities, and these measurements play a crucial rule in the diagnosis and grading of arterial stenosis. One drawback of Doppler-based blood flow quantification is that the operator has to manually specify the angle between the Doppler ultrasound beam and the vessel orientation, which is called the Doppler angle, in order to calculate flow velocities. In this paper, we will describe a computer vision approach to automate the Doppler angle estimation. Our approach starts with the segmentation of blood vessels in ultrasound color Doppler images. The segmentation step is followed by an estimation technique for the Doppler angle based on a skeleton representation of the segmented vessel. We conducted preliminary clinical experiments to evaluate the agreement between the expert operator's angle specification and the new automated method. Statistical regression analysis showed strong agreement between the manual and automated methods. We hypothesize that the automation of the Doppler angle will enhance the workflow of the ultrasound Doppler exam and achieve more standardized clinical outcome. PMID:18488268

  18. Sensitivity analysis and automation for intraoperative implementation of the atlas-based method for brain shift correction

    NASA Astrophysics Data System (ADS)

    Chen, Ishita; Simpson, Amber L.; Sun, Kay; Thompson, Reid C.; Miga, Michael I.

    2013-03-01

    The use of biomechanical models to correct the misregistration due to deformation in image guided neurosurgical systems has been a growing area of investigation. In previous work, an atlas-based inverse model was developed to account for soft-tissue deformations during image-guided surgery. Central to that methodology is a considerable amount of pre-computation and planning. The goal of this work is to evaluate techniques that could potentially reduce that burden. Distinct from previous manual techniques, an automated segmentation technique is described for the cerebrum and dural septa. The shift correction results using this automated segmentation method were compared to those using the manual methods. In addition, the extent and distribution of the surgical parameters associated with the deformation atlas were investigated by a sensitivity analysis using simulation experiments and clinical data. The shift correction results did not change significantly using the automated method (correction of 73+/-13% ) as compared to the semi-automated method from previous work (correction of 76+/-13%). The results of the sensitivity analysis show that the atlas could be constructed by coarser sampling (six fold reduction) without substantial degradation in the shift reconstruction, a decrease in preoperative computational time from 13.1+/-3.5 hours to 2.2+/-0.6 hours. The automated segmentation technique and the findings of the sensitivity study have significant impact on the reduction of pre-operative computational time, improving the utility of the atlas-based method. The work in this paper suggests that the atlas-based technique can become a `time of surgery' setup procedure rather than a pre-operative computing strategy.

  19. Doppler ultrasound evaluation in preeclampsia

    PubMed Central

    2013-01-01

    Background Worldwide preeclampsia (PE) is the leading cause of maternal death and affects 5 to 8% of pregnant women. PE is characterized by elevated blood pressure and proteinuria. Doppler Ultrasound (US) evaluation has been considered a useful method for prediction of PE; however, there is no complete data about the most frequently altered US parameters in the pathology. The aim of this study was to evaluate the uterine, umbilical, and the middle cerebral arteries using Doppler US parameters [resistance index (RI), pulsatility index (PI), notch (N), systolic peak (SP) and their combinations] in pregnant women, in order to make a global evaluation of hemodynamic repercussion caused by the established PE. Results A total of 102 pregnant Mexican women (65 PE women and 37 normotensive women) were recruited in a cases and controls study. Blood velocity waveforms from uterine, umbilical, and middle cerebral arteries, in pregnancies from 24 to 37 weeks of gestation were recorded by trans-abdominal examination with a Toshiba Ultrasound Power Vision 6000 SSA-370A, with a 3.5 MHz convex transducer. Abnormal general Doppler US profile showed a positive association with PE [odds ratio (OR) = 2.93, 95% confidence interval (CI) = 1.2 - 7.3, P = 0.021)], and a specificity and predictive positive value of 89.2% and 88.6%, respectively. Other parameters like N presence, RI and PI of umbilical artery, as well as the PI of middle cerebral artery, showed differences between groups (P values < 0.05). Conclusion General Doppler US result, as well as N from uterine vessel, RI from umbilical artery, and PI from umbilical and middle cerebral arteries in their individual form, may be considered as tools to determine hemodynamic repercussion caused by PE. PMID:24252303

  20. Ready for a paradigm shift? Part 2: introducing qualitative research methodologies and methods.

    PubMed

    Petty, Nicola J; Thomson, Oliver P; Stew, Graham

    2012-10-01

    This paper explores a number of commonly used methodologies and methods in qualitative research, namely grounded theory, case study, phenomenology, ethnography and narrative research. For each methodology a brief history of its development and variants is given, followed by typical methods of data collection and analysis. Examples of manual therapy qualitative research studies are highlighted for each methodology. Data collection methods are then discussed and include individual interviews, focus groups, observation and documentary analysis. A frequently used method of data analysis, thematic analysis, is briefly explained. Finally, the strategies to enhance the quality of qualitative research is explored and compared to those of quantitative research. PMID:22480949

  1. Method of shifting and fixing optical frequency of an optical resonator, and optical resonator made by same

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy A. (Inventor); Strekalov, Dmitry V. (Inventor); Maleki, Lute (Inventor); Matsko, Andrey B. (Inventor); Iltchenko, Vladimir S. (Inventor); Martin, Jan M. (Inventor)

    2010-01-01

    A method of shifting and fixing an optical frequency of an optical resonator to a desired optical frequency, and an optical resonator made by such a method are provided. The method includes providing an optical resonator having a surface and a refractive index, and obtaining a coating composition having a predetermined concentration of a substance and having a refractive index that is substantially similar to the refractive index of the optical resonator. The coating composition inherently possesses a thickness when it is applied as a coating. The method further includes determining a coating ratio for the surface of the optical resonator and applying the coating composition onto a portion of the surface of the optical resonator based upon the determined coating ratio.

  2. Voltage sensing systems and methods for passive compensation of temperature related intrinsic phase shift

    DOEpatents

    Davidson, James R.; Lassahn, Gordon D.

    2001-01-01

    A small sized electro-optic voltage sensor capable of accurate measurement of high levels of voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation into the sensor. A polarization beam displacer serves as a filter to separate the input beam into two beams with orthogonal linear polarizations. The beam displacer is oriented in such a way as to rotate the linearly polarized beams such that they enter a Pockels crystal at a preferred angle of 45 degrees. The beam displacer is therefore capable of causing a linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels electro-optic effect induces a differential phase shift on the major and minor axes of the input beam as it travels through the Pockels crystal, which causes the input beam to be elliptically polarized. A reflecting prism redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization representing the major and minor axes. In crystals that introduce a phase differential attributable to temperature, a compensating crystal is provided to cancel the effect of temperature on the phase differential of the input beam. The system may include a detector for converting the output beams into electrical signals, and a signal processor for determining the voltage based on an analysis of the output beams. The output beams are amplitude modulated by the frequency of the electric field and the amplitude of the output beams is proportional to the magnitude of the electric field, which is related to the voltage being measured.

  3. Tropospheric and stratospheric wind profiling with a direct detection Doppler lidar

    NASA Technical Reports Server (NTRS)

    Abreu, Vincent J.; Barnes, John E.; Fischer, Ken W.; Skinner, Wilbert R.; Mcgill, Matt J.

    1992-01-01

    The Space Physics Research Laboratory at the University of Michigan has been operating a direct detection, high resolution Doppler Lidar (HRDL) to measure winds in the boundary layer, free troposphere and lower stratosphere. A direct detection Doppler lidar measures the Doppler shift of the aerosol or Rayleigh backscattered signal, from which the wind velocity vector can be retrieved (Benedetti-Michelangeli et al, 1972, 1974; Chanin et al., 1989; Abreu et al., 1992). The system components are shown. The transmitting system is a Continuum NY-60 Nd:YAG laser frequency doubled to a wavelength of 532 nm. The laser is injection seeded for single line mode operation yielding a linewidth of 0.0045 cm(exp -1) (135 MHz) with excellent shot-to-shot frequency stability. The laser produces 60 mJ pulses and operates at a 50 Hz repetition rate for an effective output power of 3.0 W. A description of the University of Michigan's Doppler lidar is given with examples of wind profiles for the boundary layer, free troposphere, and for the lower stratosphere. The system provides a reliable method of remotely measuring the wind. The wind error is smallest in regions of high aerosols. The system also produces aerosol extinction profiles versus altitude which can be determined by the shape of the spectra. The system has been installed in a trailor so that measurements can be made for field campaigns. Winds and aerosol data are available immediately at the site for use in forecasting.

  4. Spacecraft Doppler Tracking as a Xylophone Detector of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, M.

    1995-01-01

    Spacecraft Doppler tracking is discussed for detecting gravitational waves in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. A new method is derived for removing from combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. The remaining non-zero gravitational wave signal could be used for detecting gravitational waves.

  5. Traveling Ionospheric Disturbance Characteristics Over Texas Using the TIDDBIT HF Doppler Radar

    NASA Astrophysics Data System (ADS)

    Wene, G.; Crowley, G.; Fessler, B.; Bronn, J.

    2004-05-01

    Atmospheric gravity waves (AGW) are generated by numerous lower atmospheric processes, such as storms, and by auroral processes in the ionosphere. At ionospheric heights, the motion of the neutral gas in the AGW sets the ionosphere into motion. The waves displace the isoionic contours, resulting in a travelling ionospheric disturbance (TID). TIDs can be thought of as traveling corrugations in the ionosphere, and they can seriously affect HF radio communications and surveillance systems. Consequently, one of the most sensitive methods for detecting transient changes in the ionosphere is the HF Doppler technique operating in the 3-10 MHz band. A simple Doppler system consists of a CW (continuous wave) radio transmitter and receiver, which are highly frequency-stable. When a HF radio wave is reflected from the ionosphere, movement of the reflection point during passage of a TID produces a change in phase path and a Doppler shift proportional to the time rate of change of the phase path. The Doppler system is sensitive to motions of the ionospheric reflection point, and it therefore provides an accurate measure of both the TID and AGW periods. Similarly, because the TID velocity is determined simply from triangulation using the time-delays between perturbations at different reflection points, the TID velocities are also an accurate estimate of the underlying gravity wave horizontal and vertical trace velocities. HF Doppler systems have advantages over all other techniques for the measurement of TID characteristics. They are more amenable to analysis than data from ionosonde chains, and their time resolution (30 sec) is much higher than that of ionosondes . Unlike total electron content (TEC) methods, which respond to height-integrated TID effects, the HF Doppler radar responds to TIDs at the altitude of the radio reflection point. Finally, HF Doppler systems have low power consumption, so that both spatial and temporal resolution can be maintained for many days without

  6. An Ihs-Based Enhancement Method with Improved Scale/shift Parameter of Linear Model

    NASA Astrophysics Data System (ADS)

    Bingxian, Zhang

    2016-06-01

    An IHS-based enhancement method for colour images (IEM) is presented in this paper. An improved gamma transformation was applied to enhance the brightness and texture details of colour images taken in dark conditions. Moreover, a spatial filter was used to prevent the loss of details of highlighted areas. The method was tested with the images from the database of Simon Fraser University (SFU) and from the Chinese ZIYUAN-02C satellite. The experimental results show our proposed method could effectively enhance the luminance and texture of the images, especially for those taken in dim conditions, and maintain the hue and saturation of original images.

  7. Ramsey's method of separated oscillating fields and its application to gravitationally induced quantum phase shifts

    SciTech Connect

    Abele, H.; Jenke, T.; Leeb, H.; Schmiedmayer, J.

    2010-03-15

    We propose to apply Ramsey's method of separated oscillating fields to the spectroscopy of the quantum states in the gravity potential above a horizontal mirror. This method allows a precise measurement of quantum mechanical phaseshifts of a Schroedinger wave packet bouncing off a hard surface in the gravitational field of the Earth. Measurements with ultracold neutrons will offer a sensitivity to Newton's law or hypothetical short-ranged interactions, which is about 21 orders of magnitude below the energy scale of electromagnetism.

  8. Measurement Capabilities of Single-Pulse Planar Doppler Velocimetry

    NASA Technical Reports Server (NTRS)

    McKenzie, Robert L.; Kutler, Paul F. (Technical Monitor)

    1994-01-01

    Preliminary investigations are described of a method that is capable of measuring instantaneous, 3-D, velocity vectors everywhere in a light sheet generated by a pulsed laser. The technique, here called Planar Doppler Velocimetry (PDV), is a variation of a new concept for velocity measurements that was called Doppler Global Velocimetry (DGV) in its original disclosure. The concept relies on the use of a narrowband laser and measurements of the Doppler shift of scattered light from particles moving with a flow. The Doppler shift is recorded as a variation in transmission through a sharp-edged spectral filter provided by iodine vapor in a cell. Entire fields of velocity can be determined by using a solid-state camera to record the intensity variations throughout the field of view. However, the implementation of DGV has been centered principally on the use of high power, continuous-wave, ion lasers and measurement times that are determined by the 30-ms framing times of standard video cameras. Hence, they provide velocity fields that are averaged in time at least over that period. On the other hand, the PDV concept described in this presentation incorporates a high energy, repetitively pulsed, Nd-YAG laser that is injection-seeded to make it narrowband and then frequency-doubled to provide light at frequencies absorbed by the iodine vapor. The duration of each pulse is less than 10 nanoseconds. When used in combination with nonstandard, scientific quality, solid state cameras, a sequence of images can be obtained that provides instantaneous velocity vectors everywhere in the field of view. The investigations described in this paper include an accurate characterization of the iodine cell spectral behavior and its influence on the PDV measurements, a derivation of the PDV signal analysis requirements, and the unique aspects of the pulsed laser behavior related to this application. In addition, PDV measurements are to be demonstrated using data from a rotating wheel

  9. Two-wavelength method for endoscopic shape measurement by spatial phase-shifting speckle-interferometry.

    PubMed

    Kandulla, Jochen; Kemper, Björn; Knoche, Sabine; von Bally, Gert

    2004-10-10

    A two-wavelength method for endoscopic topography reconstruction is introduced that can be applied to out-of-plane sensitive electronic-speckle-pattern interferometry systems based on rigid endoscope imaging systems. The surface measurement is performed by detection of the phase-difference distribution affected by a change in the applied laser wavelength. Furthermore, the off-axis endoscopic illumination geometry is taken into account by an approximation. Experimental results of the characterization of the endoscopic surface reconstruction technique and the measurement accuracy obtained are described and discussed. Finally, the applicability of the method is demonstrated with results from the topographic reconstruction of a free-form surface. PMID:15508598

  10. The portable Doppler: practical applications in EMS care.

    PubMed

    O'Keefe, K M; Bookman, L

    1976-12-01

    The practical application of a new, commercially available, portable Doppler ultrasound device to the operation of a busy city-county emergency department and ambulance service was investigated. An initial evaluation using healthy volunteers confirmed accuracy and reproducibility of the Doppler blood pressure readings comparable to that of auscultatory and palpatory measurement. In selected patients, the Doppler readings correlated well with readings from patients who had intra-arterial lines. When used in several low flow states, such as testing adequacy of cardiopulmonary resuscitation (CPR) and verification of electromechanical dissociation, the Doppler aided the clinical evaluation and treatment in many cases where traditional methods were useless. The Doppler was also helpful in the evaluation of local arterial injury but this unit was not found sensitive enough for venous disease. Finally, the Doppler enhanced the obtaining of vital signs in the noisy environment of our ambulances. PMID:1018378

  11. Polarimetric Doppler Weather Radar

    NASA Astrophysics Data System (ADS)

    Bringi, V. N.; Chandrasekar, V.

    2001-10-01

    This work provides a detailed introduction to the principles of Doppler and polarimetric radar, focusing in particular on their use in the analysis of weather systems. The authors first discuss underlying topics such as electromagnetic scattering, polarization, and wave propagation. They then detail the engineering aspects of pulsed Doppler polarimetric radar, before examining key applications in meteorology and remote sensing. The book is aimed at graduate students of electrical engineering and atmospheric science as well as practitioners involved in the applications of polarimetric radar.

  12. Demonstration of glass transition temperature shift in thin supported polystyrene films by internal reference method

    NASA Astrophysics Data System (ADS)

    Efremov, Mikhail Yu.; Thode, Christopher; Nealey, Paul F.

    2013-02-01

    An internal reference method is used for the first time to clearly demonstrate the glass transition temperature (Tg) depression effect in 5 nm thick polystyrene films spin-cast on silicon wafers. Initially flat films exhibit depressed Tg at approximately 85 °C. Temperature-induced dewetting on hexamethyldisilazane-treated silicon substrates leads to formation of discontinuous films with average effective thickness of 15-30 nm. Dewetted films demonstrate Tg close to the bulk value (≈ 100 °C) and are used as internal references. Data both for continuous and discontinuous films are obtained in the same experimental run for the same sample, which allows direct comparison between datasets. Phase-modulated ellipsometry in vacuum is used to monitor glass transition. Both traditional linear temperature scan method and a novel temperature modulated technique have been employed in the measurements.

  13. Measurement of Turbulence with Acoustic Doppler Current Profilers - Sources of Error and Laboratory Results

    USGS Publications Warehouse

    Nystrom, E.A.; Oberg, K.A.; Rehmann, C.R.

    2002-01-01

    Acoustic Doppler current profilers (ADCPs) provide a promising method for measuring surface-water turbulence because they can provide data from a large spatial range in a relatively short time with relative ease. Some potential sources of errors in turbulence measurements made with ADCPs include inaccuracy of Doppler-shift measurements, poor temporal and spatial measurement resolution, and inaccuracy of multi-dimensional velocities resolved from one-dimensional velocities measured at separate locations. Results from laboratory measurements of mean velocity and turbulence statistics made with two pulse-coherent ADCPs in 0.87 meters of water are used to illustrate several of inherent sources of error in ADCP turbulence measurements. Results show that processing algorithms and beam configurations have important effects on turbulence measurements. ADCPs can provide reasonable estimates of many turbulence parameters; however, the accuracy of turbulence measurements made with commercially available ADCPs is often poor in comparison to standard measurement techniques.

  14. Doppler Lidar Measurements of Tropospheric Wind Profiles Using the Aerosol Double Edge Technique

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce M.; Li, Steven X.; Mathur, Savyasachee; Korb, C. Laurence; Chen, Huailin

    2000-01-01

    The development of a ground based direct detection Doppler lidar based on the recently described aerosol double edge technique is reported. A pulsed, injection seeded Nd:YAG laser operating at 1064 nm is used to make range resolved measurements of atmospheric winds in the free troposphere. The wind measurements are determined by measuring the Doppler shift of the laser signal backscattered from atmospheric aerosols. The lidar instrument and double edge method are described and initial tropospheric wind profile measurements are presented. Wind profiles are reported for both day and night operation. The measurements extend to altitudes as high as 14 km and are compared to rawinsonde wind profile data from Dulles airport in Virginia. Vertical resolution of the lidar measurements is 330 m and the rms precision of the measurements is a low as 0.6 m/s.

  15. Orbit determination singularities in the Doppler tracking of a planetary orbiter

    NASA Technical Reports Server (NTRS)

    Wood, L. J.

    1985-01-01

    On a number of occasions, spacecraft launched by the U.S. have been placed into orbit about the moon, Venus, or Mars. It is pointed out that, in particular, in planetary orbiter missions two-way coherent Doppler data have provided the principal data type for orbit determination applications. The present investigation is concerned with the problem of orbit determination on the basis of Doppler tracking data in the case of a spacecraft in orbit about a natural body other than the earth or the sun. Attention is given to Doppler shift associated with a planetary orbiter, orbit determination using a zeroth-order model for the Doppler shift, and orbit determination using a first-order model for the Doppler shift.

  16. Laser Doppler measurement techniques for spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.; Gagliardi, Robert M.

    1986-01-01

    Two techniques are proposed for using laser links to measure the relative radial velocity of two spacecraft. The first technique determines the relative radial velocity from a measurement of the two-way Doppler shift on a transponded radio-frequency subcarrier. The subcarrier intensity-modulates reciprocating laser beams. The second technique determines the relative radial velocity from a measurement of the two-way Doppler shift on an optical frequency carrier which is transponded between spacecraft using optical Costas loops. The first technique might be used in conjunction with noncoherent optical communications, while the second technique is compatible with coherent optical communications. The first technique simultaneously exploits the diffraction advantage of laser beams and the maturity of radio-frequency phase-locked loop technology. The second technique exploits both the diffraction advantage of laser beams and the large Doppler effect at optical frequencies. The second technique has the potential for greater accuracy; unfortunately, it is more difficult to implement since it involves optical Costas loops.

  17. Selection effects in Doppler velocity planet searches

    NASA Astrophysics Data System (ADS)

    O'Toole, Simon; Tinney, Chris; Jones, Hugh

    2008-05-01

    The majority of extra-solar planets have been discovered by measuring the Doppler velocities of the host star. Like all exoplanet detection methods, the Doppler method is rife with observational biases. Before any robust comparison of mass, orbital period and eccentricity distributions can be made with theory, a detailed understanding of these selection effects is required, something which up to now is lacking. We present here a progress report on our analysis of the selection effects present in Anglo-Australian Planet Search data, including the methodology used and some preliminary results.

  18. Electrical system using phase-shifted carrier signals and related operating methods

    DOEpatents

    Welchko, Brian A; Campbell, Jeremy B

    2012-09-18

    An automotive drive system and methods for making the same are provided. The system includes a three-phase motor and an inverter module. The three-phase motor includes a first set of windings each having a first magnetic polarity; and a second set of windings each having a second magnetic polarity that is opposite the first magnetic polarity. The first set of windings being electrically isolated from the second set of windings. The inverter module includes a first set of phase legs and a second set of phase legs. Each one of the first set of phase legs is coupled to a corresponding phase of the first set of windings, and each one of the second set of phase legs is coupled to a corresponding phase of the second set of windings.

  19. Quantitative analysis of aortic regurgitation: real-time 3-dimensional and 2-dimensional color Doppler echocardiographic method--a clinical and a chronic animal study

    NASA Technical Reports Server (NTRS)

    Shiota, Takahiro; Jones, Michael; Tsujino, Hiroyuki; Qin, Jian Xin; Zetts, Arthur D.; Greenberg, Neil L.; Cardon, Lisa A.; Panza, Julio A.; Thomas, James D.

    2002-01-01

    BACKGROUND: For evaluating patients with aortic regurgitation (AR), regurgitant volumes, left ventricular (LV) stroke volumes (SV), and absolute LV volumes are valuable indices. AIM: The aim of this study was to validate the combination of real-time 3-dimensional echocardiography (3DE) and semiautomated digital color Doppler cardiac flow measurement (ACM) for quantifying absolute LV volumes, LVSV, and AR volumes using an animal model of chronic AR and to investigate its clinical applicability. METHODS: In 8 sheep, a total of 26 hemodynamic states were obtained pharmacologically 20 weeks after the aortic valve noncoronary (n = 4) or right coronary (n = 4) leaflet was incised to produce AR. Reference standard LVSV and AR volume were determined using the electromagnetic flow method (EM). Simultaneous epicardial real-time 3DE studies were performed to obtain LV end-diastolic volumes (LVEDV), end-systolic volumes (LVESV), and LVSV by subtracting LVESV from LVEDV. Simultaneous ACM was performed to obtain LVSV and transmitral flows; AR volume was calculated by subtracting transmitral flow volume from LVSV. In a total of 19 patients with AR, real-time 3DE and ACM were used to obtain LVSVs and these were compared with each other. RESULTS: A strong relationship was found between LVSV derived from EM and those from the real-time 3DE (r = 0.93, P <.001, mean difference (3D - EM) = -1.0 +/- 9.8 mL). A good relationship between LVSV and AR volumes derived from EM and those by ACM was found (r = 0.88, P <.001). A good relationship between LVSV derived from real-time 3DE and that from ACM was observed (r = 0.73, P <.01, mean difference = 2.5 +/- 7.9 mL). In patients, a good relationship between LVSV obtained by real-time 3DE and ACM was found (r = 0.90, P <.001, mean difference = 0.6 +/- 9.8 mL). CONCLUSION: The combination of ACM and real-time 3DE for quantifying LV volumes, LVSV, and AR volumes was validated by the chronic animal study and was shown to be clinically applicable.

  20. Finnish Meteorological Institute Doppler Lidar

    SciTech Connect

    Ewan OConnor

    2015-03-27

    This doppler lidar system provides co-polar and cross polar attenuated backscatter coefficients,signal strength, and doppler velocities in the cloud and in the boundary level, including uncertainties for all parameters. Using the doppler beam swinging DBS technique, and Vertical Azimuthal Display (VAD) this system also provides vertical profiles of horizontal winds.

  1. The Doppler Pendulum Experiment

    ERIC Educational Resources Information Center

    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…

  2. Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

    DOEpatents

    Moore, David S.; Schmidt, Stephen C.

    1985-01-01

    A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

  3. Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

    DOEpatents

    Moore, D.S.; Schmidt, S.C.

    1983-12-16

    A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

  4. A shifting paradigm: Teachers' beliefs and methods for fostering ecological literacy in two public charter schools

    NASA Astrophysics Data System (ADS)

    Sterling, Evan P.

    Ecological literacy is measured by a person's ability to understand the natural systems that make life on earth possible and how to live in accordance with those systems. The emergence of the pedagogies of place- and community-based education during the past two decades provides a possible avenue for fostering ecological literacy in schools. This thesis explores the following research questions: 1) How is ecological literacy fostered in two Alaskan public charter schools? 2) What are teachers' beliefs in these two schools about the way children and youth develop ecological literacy? 3) What are effective teaching methods and what are the challenges in engaging students in ecological literacy? Semi-structured interviews were conducted with six K--12 teachers in two public charter schools in Alaska in order to investigate these questions, and relevant examples of student work were collected for study as well. Qualitative data analysis revealed several emergent themes: the need for real-world connections to curriculum; the necessity of time spent outdoors at a young age; the long-term and holistic nature of ecological literacy development; and the importance of family and community role models in developing connections with the natural world. Based upon the research findings, several recommendations are made to support the efforts of teachers in these schools and elsewhere for fostering ecological literacy in children and youth.

  5. Monolithic Single-Mode DFB Laser Array with Precise Wavelength Control for Optoelectronic Integration using an Equivalent Phase Shift Method

    NASA Astrophysics Data System (ADS)

    Li, Jingsi; Cheng, Julian; Microelectronics Research Center Team

    2013-03-01

    The integrated distributed feedback (DFB) laser array is a key component in photonic integrated circuits for wavelength-division multiplexing (WDM) system. However, it is difficult to precisely control the wavelength of individual lasers. When the rear facet of the laser is coated with a high-reflectivity mirror, a random phase change is introduced that shifts the lasing wavelength, making monolithic integration of a wavelength-controlled WDM array very difficult. To solve this problem, we propose a method to precisely control the lasing wavelength of DFB lasers over a wide range by introducing an equivalent phase shift in the cavity using sampled Bragg gratings, using wafer-scale optical lithography and requiring only coarse dimension control. The wavelength can be fine-tuned by applying different DC currents. It is shown that a WDM-DFB laser array with uniform wavelength spacing can be controlled accurately in this manner. Integrated arrays of single-mode DFB lasers for WDM systems can thus be fabricated in a low-cost manner without using low-throughput e-beam lithography, and is scalable for mass-manufacturing.

  6. An embedded three-dimensional profilometry based on a combination of gray-code and phase shifting method

    NASA Astrophysics Data System (ADS)

    Li, Dong; Tian, Jindong

    2010-11-01

    An embedded three-dimensional (3-D) profilometry system based on a combination of gray-code and phase shifting (GCPS) method is proposed. This system consists of a digital-micromirror-device (DMD) based video projector, a high-speed CCD camera and an embedded digital signal processing hardware system based on DSP. In this technique, seven gray-code patterns and three sinusoidal fringe patterns with 120-deg phase shift are integrated in red, green and blue channels to form four color fringe patterns. When the four color fringe patterns are sent to the DMD based projector without color filter, the previous gray-code patterns and three sinusoidal fringe patterns are repeatedly projected to an object surface in gray-scale sequentially. These fringe patterns deformed by the object surface are captured by a high-speed CCD camera synchronized with the projector. An embedded hardware system is developed for synchronization between the camera and the projector and taking full advantage of DSP parallel processing capability for real-time phase retrieve and 3-D reconstruction. Since the number of projected images of GCPS is reduced from 11 to 4, the measurement speed is enhanced dramatically. Experimental results demonstrated the feasibility of the proposed technique for high-speed 3-D shape measurement.

  7. Method of hybrid multiplexing for fiber-optic Fabry-Perot sensors utilizing frequency-shifted interferometry.

    PubMed

    Ou, Yiwen; Zhou, Ciming; Zheng, Angui; Cheng, Chunfu; Fan, Dian; Yin, Jiadi; Tian, Hui; Li, Mengmeng; Lu, Ying

    2014-12-10

    Experimental and theoretical research on hybrid multiplexing for fiber-optic Fabry-Perot (F-P) sensors based on frequency-shifted interferometry is presented. Four F-P sensors multiplexed in a hybrid configuration were experimentally investigated. The location of each multiplexed sensor was retrieved by performing the fast Fourier transform, and the reflection spectrum of each sensor was also obtained in spite of the spectral overlap, which was consistent with the results measured by an optical spectrum analyzer. With theoretical modeling, the maximum sensor number of a two-channel hybrid multiplexing system reaches 26 with crosstalk of less than -50  dB and a maximum frequency-domain signal-to-noise ratio (SNR) of ∼25  dB, when the source power is 2 mW and the sensor separation is optimal, i.e., 40 m. And the sensor number is almost twice that multiplexed by a serial system under the same conditions. An SNR improvement of 3.9 dB can be achieved by using a Hamming window in a noise-free system compared with a Hanning window. In addition, we applied the experimental multiplexing system to a strain sensing test. The cavity lengths and cavity-length shifts of the four F-P sensors were demodulated, which was consistent with the actual situation. It provides a new feasible method to multiplex F-P sensors at large scale. PMID:25608081

  8. Noise and Dynamic Range in Multiplexed Photonic Doppler Velocimetry

    NASA Astrophysics Data System (ADS)

    Daykin, Edward; Jung, Chan; Miller, Edward; Pena, Michael; Perez, Carlos; Strand, Oliver

    2015-06-01

    We have designed and built the Multiplexed Photonic Doppler Velocimeter (MPDV) for use on any class of shock physics experiments that requires a large number of spatial points to be measured. The MPDV uses the heterodyne method to either multiplex or up-shift data channels in the frequency domain, and also employs fiber-optic delays to multiplex additional data channels in the time domain. MPDV differs in architecture from the Photonic Doppler Velocimeter (PDV) in that the MPDV employs an Erbium Doped Fiber Amplifier (EDFA) for small signal optical pre-amplification prior to photo detection. Optical amplification allows for two aspects of MPDV operation that differ from PDV: 1) use of low power (eye-safe) lasers, and 2) ability to time multiplex with minimal degradation to the signal-to-noise ratio (SNR). However, use of EDFA optical amplification within PDV or MPDV architecture also contributes noise to the spectrogram. EDFA optical noise will impact the SNR of MPDV data, and is dependent on amplifier performance, laser power, as well as optical signal attenuation due to fiber-optic delays and components. We will review this dependence and the trade-offs that exist between SNR and multiplexing architectures.

  9. Investigations of atmospheric dynamics using a CW Doppler sounder array

    NASA Technical Reports Server (NTRS)

    Rao, G. L.

    1974-01-01

    A three-dimensional CW Doppler sounding system currently under operation at the NASA-Marshall Space Flight Center, Alabama is described. The properties of the neutral atmosphere are discussed along with the theory of Doppler sounding technique. Methods of data analyses used to investigate the dynamical phenomena at the ionospheric heights are presented and suggestions for future investigations provided.

  10. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    PubMed Central

    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

  11. Feasibility study of a high-spatial resolution x-ray computed tomography using sub-pixel shift method

    SciTech Connect

    Yoneyama, Akio Baba, Rika; Sumitani, Kazushi; Hirai, Yasuharu

    2015-02-23

    A high-spatial resolution X-ray computed tomography (CT) adopting a sub-pixel shift method has been developed. By calculating sectional images, using plural CT datasets obtained by scanning the X-ray imager, the spatial resolution can be reduced relative to the sub-pixel size of an X-ray imager. Feasibility observations of a biomedical sample were performed using 12-keV monochromatic synchrotron radiation and a photon-counting X-ray imager 174-μm pixels in size. Four CT measurements were performed to obtain datasets at different positions of the X-ray imager. Fine sectional images were obtained successfully, and the spatial resolution was estimated as 80-μm, which corresponds to just under half the pixel size of the imager. In addition, a fine 3D image was also obtained by scanning the imager two-dimensionally.

  12. DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS

    SciTech Connect

    Showman, Adam P.; Lewis, Nikole K.; Fortney, Jonathan J.; Shabram, Megan

    2013-01-01

    The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measurements can place powerful constraints on the meteorology. We show that the atmospheric circulation-and Doppler signature-of hot Jupiters splits into two regimes. Under weak stellar insolation, the day-night thermal forcing generates fast zonal jet streams from the interaction of atmospheric waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows toward Earth in some regions and away from Earth in others, leading to a Doppler signature exhibiting superposed blueshifted and redshifted components. Under intense stellar insolation, however, the strong thermal forcing damps these planetary-scale waves, inhibiting their ability to generate jets. Strong frictional drag likewise damps these waves and inhibits jet formation. As a result, this second regime exhibits a circulation dominated by high-altitude, day-to-night airflow, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art circulation models including non-gray radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that cool planets like GJ 436b lie in the first regime, HD 189733b is transitional, while planets hotter than HD 209458b lie in the second regime. Moreover, we show how the amplitude of the Doppler shifts constrains the strength of frictional drag in the upper atmospheres of hot Jupiters. If due to winds, the {approx}2 km s{sup -1} blueshift inferred on HD 209458b may require drag time constants as short as 10{sup 4}-10{sup 6} s, possibly the result of Lorentz-force braking on this planet's hot dayside.

  13. Doppler imaging with dual-detection full-range frequency domain optical coherence tomography

    PubMed Central

    Meemon, Panomsak; Lee, Kye-Sung; Rolland, Jannick P.

    2010-01-01

    Most of full-range techniques for Frequency Domain Optical Coherence Tomography (FD-OCT) reported to date utilize the phase relation between consecutive axial lines to reconstruct a complex interference signal and hence may exhibit degradation in either mirror image suppression performance or detectable velocity dynamic range or both when monitoring a moving sample such as flow activity. We have previously reported a technique of mirror image removal by simultaneous detection of the quadrature components of a complex spectral interference called a Dual-Detection Frequency Domain OCT (DD-FD-OCT) [Opt. Lett. 35, 1058-1060 (2010)]. The technique enables full range imaging without any loss of acquisition speed and is intrinsically less sensitive to phase errors generated by involuntary movements of the subject. In this paper, we demonstrate the application of the DD-FD-OCT to a phase-resolved Doppler imaging without degradation in either mirror image suppression performance or detectable velocity dynamic range that were observed in other full-range Doppler methods. In order to accommodate for Doppler imaging, we have developed a fiber-based DD-FD-OCT that more efficiently utilizes the source power compared with the previous free-space DD-FD-OCT. In addition, the velocity sensitivity of the phase-resolved DD-FD-OCT was investigated, and the relation between the measured Doppler phase shift and set flow velocity of a flow phantom was verified. Finally, we demonstrate the Doppler imaging using the DD-FD-OCT in a biological sample. PMID:21258488

  14. Shifting tools

    SciTech Connect

    Fisher, E.P.; Welch, W.R.

    1984-03-13

    An improved shifting tool connectable in a well tool string and useful to engage and position a slidable sleeve in a sliding sleeve device in a well flow conductor. The selectively profiled shifting tool keys provide better fit with and more contact area between keys and slidable sleeves. When the engaged slidable sleeve cannot be moved up and the shifting tool is not automatically disengaged, emergency disengagement means may be utilized by applying upward force to the shifting tool sufficient to shear pins and cause all keys to be cammed inwardly at both ends to completely disengage for removal of the shifting tool from the sliding sleeve device.

  15. Imaging nanoparticle flow using magneto-motive optical Doppler tomography.

    PubMed

    Kim, Jeehyun; Oh, Junghwan; Milner, Thomas E; Nelson, J Stuart

    2007-01-24

    We introduce a novel approach for imaging solutions of superparamagnetic iron oxide (SPIO) nanoparticles using magneto-motive optical Doppler tomography (MM-ODT). MM-ODT combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect nanoparticles flowing through a microfluidic channel. A solenoid with a cone-shaped ferrite core extensively increased the magnetic field strength (B(max) = 1 T, [Formula: see text]) at the tip of the core and also focused the magnetic field in microfluidic channels containing nanoparticle solutions. Nanoparticle contrast was demonstrated in a microfluidic channel filled with an SPIO solution by imaging the Doppler frequency shift which was observed independently of the nanoparticle flow rate and direction. Results suggest that MM-ODT may be applied to image Doppler shift of SPIO nanoparticles in microfluidic flows with high contrast. PMID:19636123

  16. Identifying Shifts in Leaf-Litter Ant Assemblages (Hymenoptera: Formicidae) across Ecosystem Boundaries Using Multiple Sampling Methods

    PubMed Central

    Wiezik, Michal; Svitok, Marek; Wieziková, Adela; Dovčiak, Martin

    2015-01-01

    Global or regional environmental changes in climate or land use have been increasingly implied in shifts in boundaries (ecotones) between adjacent ecosystems such as beech or oak-dominated forests and forest-steppe ecotones that frequently co-occur near the southern range limits of deciduous forest biome in Europe. Yet, our ability to detect changes in biological communities across these ecosystems, or to understand their environmental drivers, can be hampered when different sampling methods are required to characterize biological communities of the adjacent but ecologically different ecosystems. Ants (Hymenoptera: Formicidae) have been shown to be particularly sensitive to changes in temperature and vegetation and they require different sampling methods in closed vs. open habitats. We compared ant assemblages of closed-forests (beech- or oak-dominated) and open forest-steppe habitats in southwestern Carpathians using methods for closed-forest (litter sifting) and open habitats (pitfall trapping), and developed an integrated sampling approach to characterize changes in ant assemblages across these adjacent ecosystems. Using both methods, we collected 5,328 individual ant workers from 28 species. Neither method represented ant communities completely, but pitfall trapping accounted for more species (24) than litter sifting (16). Although pitfall trapping characterized differences in species richness and composition among the ecosystems better, with beech forest being most species poor and ecotone most species rich, litter sifting was more successful in identifying characteristic litter-dwelling species in oak-dominated forest. The integrated sampling approach using both methods yielded more accurate characterization of species richness and composition, and particularly so in species-rich forest-steppe habitat where the combined sample identified significantly higher number of species compared to either of the two methods on their own. Thus, an integrated sampling

  17. Velocity precision measurements using laser Doppler anemometry

    NASA Astrophysics Data System (ADS)

    Dopheide, D.; Taux, G.; Narjes, L.

    1985-07-01

    A Laser Doppler Anemometer (LDA) was calibrated to determine its applicability to high pressure measurements (up to 10 bars) for industrial purposes. The measurement procedure with LDA and the experimental computerized layouts are presented. The calibration procedure is based on absolute accuracy of Doppler frequency and calibration of interference strip intervals. A four-quadrant detector allows comparison of the interference strip distance measurements and computer profiles. Further development of LDA is recommended to increase accuracy (0.1% inaccuracy) and to apply the method industrially.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Design and Implementation of High Frequency Ultrasound Pulsed-Wave Doppler Using FPGA

    PubMed Central

    Hu, Chang-hong; Zhou, Qifa; Shung, K. Kirk

    2009-01-01

    The development of a field-programmable gate array (FPGA)-based pulsed-wave Doppler processing approach in pure digital domain is reported in this paper. After the ultrasound signals are digitized, directional Doppler frequency shifts are obtained with a digital-down converter followed by a low-pass filter. A Doppler spectrum is then calculated using the complex fast Fourier transform core inside the FPGA. In this approach, a pulsed-wave Doppler implementation core with reconfigurable and real-time processing capability is achieved. PMID:18986909

  20. Doppler radar results

    NASA Technical Reports Server (NTRS)

    Bracalente, Emedio M.

    1992-01-01

    The topics are covered in viewgraph form and include the following: (1) a summary of radar flight data collected; (2) a video of combined aft cockpit, nose camera, and radar hazard displays; (3) a comparison of airborne radar F-factor measurements with in situ and Terminal Doppler Weather Radar (TDWR) F-factors for some sample events; and (4) a summary of wind shear detection performance.

  1. Doppler Optical Coherence Tomography

    PubMed Central

    Leitgeb, Rainer A.; Werkmeister, René M.; Blatter, Cedric; Schmetterer, Leopold

    2014-01-01

    Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A common problem with the technique is that the Doppler angle is not known and several approaches have been realized to obtain absolute velocity and flow data from the retina. Additional studies are required to elucidate which of these techniques is most promising. In the recent years, however, several groups have shown that data can be obtained with high validity and reproducibility. In addition, several groups have published values for total retinal blood flow. Another promising application relates to non-invasive angiography. As compared to standard techniques such as fluorescein and indocyanine-green angiography the technique offers two major advantages: no dye is required and depth resolution is required is provided. As such Doppler OCT has the potential to improve our abilities to diagnose and monitor ocular vascular diseases. PMID:24704352

  2. Doppler optical coherence tomography.

    PubMed

    Leitgeb, Rainer A; Werkmeister, René M; Blatter, Cedric; Schmetterer, Leopold

    2014-07-01

    Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A common problem with the technique is that the Doppler angle is not known and several approaches have been realized to obtain absolute velocity and flow data from the retina. Additional studies are required to elucidate which of these techniques is most promising. In the recent years, however, several groups have shown that data can be obtained with high validity and reproducibility. In addition, several groups have published values for total retinal blood flow. Another promising application relates to non-invasive angiography. As compared to standard techniques such as fluorescein and indocyanine-green angiography the technique offers two major advantages: no dye is required and depth resolution is required is provided. As such Doppler OCT has the potential to improve our abilities to diagnose and monitor ocular vascular diseases. PMID:24704352

  3. The superiority of combined continuous wave Doppler examination over periorbital Doppler for the detection of extracranial carotid disease.

    PubMed Central

    Trockel, U; Hennerici, M; Aulich, A; Sandmann, W

    1984-01-01

    Non-invasive examination of 431 vessels in 333 patients with cerebrovascular disease in all stages was performed in order to compare the reliability of the periorbital Doppler test alone and together with the more difficult insonation of the carotid arteries in the neck (combined Doppler). These findings were compared with those of subsequent arteriography. Extracranial obstructive (greater than 50%) carotid disease was detected with 100% sensitivity by the combined Doppler, but with only 48% sensitivity by the periorbital indirect test. The specific ability of both methods to identify non-stenotic carotid arteries (less than 50%) was similar at about 98%. Only the combined Doppler examination reliably differentiated various degrees of obstruction, comparable to that obtained with arteriography. Non-obstructive plaques could not be detected or excluded by either Doppler test. More refined methods will be necessary for their evaluation. Images PMID:6693913

  4. Management of the baseline shift using a new and simple method for respiratory-gated radiation therapy: Detectability and effectiveness of a flexible monitoring system

    SciTech Connect

    Tachibana, Hidenobu; Kitamura, Nozomi; Ito, Yasushi; Kawai, Daisuke; Nakajima, Masaru; Tsuda, Akihisa; Shiizuka, Hisao

    2011-07-15

    Purpose: In respiratory-gated radiation therapy, a baseline shift decreases the accuracy of target coverage and organs at risk (OAR) sparing. The effectiveness of audio-feedback and audio-visual feedback in correcting the baseline shift in the breathing pattern of the patient has been demonstrated previously. However, the baseline shift derived from the intrafraction motion of the patient's body cannot be corrected by these methods. In the present study, the authors designed and developed a simple and flexible system. Methods: The system consisted of a web camera and a computer running our in-house software. The in-house software was adapted to template matching and also to no preimage processing. The system was capable of monitoring the baseline shift in the intrafraction motion of the patient's body. Another marker box was used to monitor the baseline shift due to the flexible setups required of a marker box for gated signals. The system accuracy was evaluated by employing a respiratory motion phantom and was found to be within AAPM Task Group 142 tolerance (positional accuracy <2 mm and temporal accuracy <100 ms) for respiratory-gated radiation therapy. Additionally, the effectiveness of this flexible and independent system in gated treatment was investigated in healthy volunteers, in terms of the results from the differences in the baseline shift detectable between the marker positions, which the authors evaluated statistically. Results: The movement of the marker on the sternum [1.599 {+-} 0.622 mm (1 SD)] was substantially decreased as compared with the abdomen [6.547 {+-} 0.962 mm (1 SD)]. Additionally, in all of the volunteers, the baseline shifts for the sternum [-0.136 {+-} 0.868 (2 SD)] were in better agreement with the nominal baseline shifts than was the case for the abdomen [-0.722 {+-} 1.56 mm (2 SD)]. The baseline shifts could be accurately measured and detected using the monitoring system, which could acquire the movement of the marker on the

  5. Is Doppler ultrasound useful for evaluating gestational trophoblastic disease?

    PubMed Central

    Lin, Lawrence H; Bernardes, Lisandra S; Hase, Eliane A; Fushida, Koji; Francisco, Rossana P V

    2015-01-01

    Doppler ultrasound is a non-invasive method for evaluating vascularization and is widely used in clinical practice. Gestational trophoblastic neoplasia includes a group of highly vascularized malignancies derived from placental cells. This review summarizes data found in the literature regarding the applications of Doppler ultrasound in managing patients with gestational trophoblastic neoplasia. The PubMed/Medline, Web of Science, Cochrane and LILACS databases were searched for articles published in English until 2014 using the following keywords: “Gestational trophoblastic disease AND Ultrasonography, Doppler.” Twenty-eight articles met the inclusion criteria and were separated into the 4 following groups according to the aim of the study. 1 Doppler ultrasound does not seem to be capable of differentiating partial from complete moles, but it might be useful when evaluating pregnancies in which a complete mole coexists with a normal fetus. 2 There is controversy in the role of uterine artery Doppler velocimetry in the prediction of development of gestational trophoblastic neoplasia. 3 Doppler ultrasound is a useful tool in the diagnosis of gestational trophoblastic neoplasia because abnormal myometrial vascularization and lower uterine artery Doppler indices seem to be correlated with invasive disease. 4 Lower uterine artery Doppler indices in the diagnosis of gestational trophoblastic neoplasia are associated with methotrexate resistance and might play a role in prognosis. CONCLUSION: Several studies support the importance of Doppler ultrasound in the management of patients with gestational trophoblastic neoplasia, particularly the role of Doppler velocimetry in the prediction of trophoblastic neoplasia and the chemoresistance of trophoblastic tumors. Doppler findings should be used as ancillary tools, along with human chorionic gonadotropin assessment, in the diagnosis of gestational trophoblastic neoplasia. PMID:26735221

  6. Efficient implementation of three-dimensional reference interaction site model self-consistent-field method: Application to solvatochromic shift calculations

    NASA Astrophysics Data System (ADS)

    Minezawa, Noriyuki; Kato, Shigeki

    2007-02-01

    The authors present an implementation of the three-dimensional reference interaction site model self-consistent-field (3D-RISM-SCF) method. First, they introduce a robust and efficient algorithm for solving the 3D-RISM equation. The algorithm is a hybrid of the Newton-Raphson and Picard methods. The Jacobian matrix is analytically expressed in a computationally useful form. Second, they discuss the solute-solvent electrostatic interaction. For the solute to solvent route, the electrostatic potential (ESP) map on a 3D grid is constructed directly from the electron density. The charge fitting procedure is not required to determine the ESP. For the solvent to solute route, the ESP acting on the solute molecule is derived from the solvent charge distribution obtained by solving the 3D-RISM equation. Matrix elements of the solute-solvent interaction are evaluated by the direct numerical integration. A remarkable reduction in the computational time is observed in both routes. Finally, the authors implement the first derivatives of the free energy with respect to the solute nuclear coordinates. They apply the present method to "solute" water and formaldehyde in aqueous solvent using the simple point charge model, and the results are compared with those from other methods: the six-dimensional molecular Ornstein-Zernike SCF, the one-dimensional site-site RISM-SCF, and the polarizable continuum model. The authors also calculate the solvatochromic shifts of acetone, benzonitrile, and nitrobenzene using the present method and compare them with the experimental and other theoretical results.

  7. Analyzing the special PFG signal attenuation behavior of intermolecular MQC via the effective phase shift diffusion equation method

    NASA Astrophysics Data System (ADS)

    Lin, Guoxing

    2015-10-01

    Inter-molecular multiple quantum coherence (iMQC) has important applications in NMR and MRI. However, the current theoretical methods still have some difficulties in analyzing the behavior of iMQC signal attenuation of pulsed field gradient diffusion experiments. In this paper, the iMQC diffusion experiments were analyzed by an effective phase shift diffusion equation (EPSDE) method, which is based on the idea that the accumulating phase shift (APS) can be viewed as the result of a diffusion process in virtual phase space (VPS) with effective diffusion coefficient K2(t) D (rad2/s) where K ( t ) = ∫0 t γ g ( t ' ) d t ' is a wavenumber and D is the physical diffusion coefficient of the spin carrier in the real space. The term K(ttot) z1 needs to be added to the APS when K(ttot) is not zero. Most of the time, K(ttot) equals zero. However, in iMQC experiments, the condition K(ttot) equaling zero or being non-zero for each spin depends on the gradient pulse setting. The signal attenuations of these two types of iMQC, zero or non-zero K(ttot), were analyzed in detail for free and restricted diffusions, which shows that there are significant differences between these two types of iMQC. Particularly, if an apparent diffusion coefficient Dapp is used to analyze the signal attenuation, it equals nD for zero K(ttot) which agrees with current theoretical and experimental reports, while for non-zero K(ttot), it equals (2n - 1) D which agrees with experimental results from the literature; there are no similar theoretical results reported for comparison. The result that Dapp equals (2n - 1) D is important because the higher value of Dapp means that non-zero K(ttot) iMQC can potentially provide more contrast and measure slower diffusion rates than zero K(ttot) iMQC. The EPSDE method provides a new way to analyze iMQC diffusion experiments.

  8. Everyday relativity and the Doppler effect

    NASA Astrophysics Data System (ADS)

    Picton Drake, Samuel; Purvis, Alan

    2014-01-01

    It is generally believed that special relativistic effects are important only when studying objects moving at speeds close to that of light. This belief leaves many practicing scientists and engineers with the impression that an understanding of relativity is not necessary for their day jobs. Our aim is to show that the ideas and mathematics of the special theory of relativity are used in practical applications involving objects moving much slower than the speed of light. In particular, we show how the Doppler shift for sound and light can be calculated from the postulates of relativity.

  9. Doppler cooling to the quantum limit.

    PubMed

    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

  10. [Characterization and comparison of the doppler compensation acoustic wave in Hipposideros armiger].

    PubMed

    Wang, Xu-Zhong; Hu, Kai-Liang; Wei, Li; Xu, Dong; Zhang, Li-Biao

    2010-12-01

    We used the pendulum device to study Doppler-shifted compensation of great leaf-nosed bat (Hipposideros armiger). The bats' echolocation calls were recorded by the Ultrasound Detector both under the rest condition and Doppler shift condition. Then we analyzed the calls with Avisoft software. Our results suggested that when H. armiger was approaching the target, it showed positive Doppler shift compensation: call frequency and the velocity (v) were positive correlated. Call frequency fell to minimum when the bats' relative velocity reached to maximum; likewise call frequency raised to the resting condition frequency when the relative velocity became zero. Negative Doppler shift compensation occurred when bats were far away from the target. Under negative Doppler shift compensation condition, we found call frequency and velocity were positive correlated as well, and moreover, call frequency raised to maximum again while the bats had their minus direction's maximal relative velocity. However, under this status, the elevated value was much lower than the depressed value under positive compensation at the same velocity. The frequency of occurrence of negative compensation was obviously less frequent than that under positive compensation condition. Therefore, we inferred that the two characteristics of the negative Doppler shift compensation mentioned above may be the coactions consequence of the bio-structural restriction and natural selection. PMID:21174358

  11. Chemical-shift tensors of heavy nuclei in network solids: a DFT/ZORA investigation of (207)Pb chemical-shift tensors using the bond-valence method.

    PubMed

    Alkan, Fahri; Dybowski, C

    2015-10-14

    Cluster models are used in calculation of (207)Pb NMR magnetic-shielding parameters of α-PbO, β-PbO, Pb3O4, Pb2SnO4, PbF2, PbCl2, PbBr2, PbClOH, PbBrOH, PbIOH, PbSiO3, and Pb3(PO4)2. We examine the effects of cluster size, method of termination of the cluster, charge on the cluster, introduction of exact exchange, and relativistic effects on calculation of magnetic-shielding tensors with density functional theory. Proper termination of the cluster for a network solid, including approximations such as compensation of charge by the bond-valence (BV) method, is essential to provide results that agree with experiment. The inclusion of relativistic effects at the spin-orbit level for such heavy nuclei is an essential factor in achieving agreement with experiment. PMID:26345261

  12. Wavelet and model-based spectral analysis of color doppler optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Choma, Michael A.; Yazdanfar, Siavash; Izatt, Joseph A.

    2006-07-01

    Color doppler optical coherence tomography (CD-OCT) uses time-frequency analysis (TFA) to extract motion-induced Doppler shifted in the interferometric OCT signal. In this paper, the performance of three TFAs are compared in a scattering flow phantom and in in vivo human retina: the short-time Fourier transform, the Morlet-wavelet transform, and the short-time MUSIC transform (STMT). The STMT is a new TFA that incorporates the MUSIC eigenfrequency estimator in a generalized short-time framework. The Morlet transform excels at identifying blood vessels, while the STMT is the most accurate predictor of Doppler shift frequency.

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

    PubMed

    Coman, Ioan M; Popescu, Bogdan A

    2015-01-01

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

  14. Clinical applications of doppler ultrasound

    SciTech Connect

    Taylor, K.J.W.; Burns, P.N.; Well, P.N.T.

    1987-01-01

    This book introduces a guide to the physical principles and instrumentation of duplex Doppler ultrasound and its applications in obstetrics, gynecology, neonatology, gastroentology, and evaluation of peripheral vascular disease. The book provides information needed to perform Doppler ultrasound examinations and interpret the results. An introduction to Doppler physics and instrumentation is followed by a thorough review of hemodynamics, which explains the principles underlying interpretation of Doppler signals. Of special note is the state-of-the-art coverage of new applications of Doppler in recognition of high-risk pregnancy, diagnosis of intrauterine growth retardation, investigation of neonatal blood flow, evaluation of first-trimester pregnancy, and diagnosis of gastrointestinal disease. The book also offers guidelines on the use of Doppler ultrasound in diagnosing carotid disease, deep venous thrombosis, and aorta/femoral disease.

  15. Laser Doppler diagnostics for orthodontia

    NASA Astrophysics Data System (ADS)

    Ryzhkova, Anastasia V.; Lebedeva, Nina G.; Sedykh, Alexey V.; Ulyanov, Sergey S.; Lepilin, Alexander V.; Kharish, Natalia A.

    2004-06-01

    The results of statistical analysis of Doppler spectra of intensity fluctuations of light, scattered from mucous membrane of oral cavity of healthy volunteers and patients, abused by the orthodontic diseases, are presented. Analysis of Doppler spectra, obtained from tooth pulp of patients, is carried out. New approach to monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of Doppler measuring system on formation of the output signal is studied.

  16. The second-order gravitational red shift

    NASA Technical Reports Server (NTRS)

    Jaffe, J.

    1973-01-01

    The direct measurement of the nonlinear term of the gravitational field equations by using very stable clocks is discussed along with measuring the perhelion advance of a planet or satellite. These are considered measurements of the second-order gravitational red shift. The exact expression for the frequency shift of light in a gravitational field is derived. Other topics discussed include: The Doppler-cancelling technique; the second-order red shift in a spherically symmetric gravitational field; finite signal transit time; and the reality and interpretation of coordinates in the second-order red shift experiment.

  17. Shifting Attention

    ERIC Educational Resources Information Center

    Ingram, Jenni

    2014-01-01

    This article examines the shifts in attention and focus as one teacher introduces and explains an image that represents the processes involved in a numeric problem that his students have been working on. This paper takes a micro-analytic approach to examine how the focus of attention shifts through what the teacher and students do and say in the…

  18. Tropospheric Wind Profile Measurements with a Direct Detection Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce M.; Li, Steven X.; Korb, C. Laurence; Chen, Huailin; Mathur, Savyasachee

    1998-01-01

    Research has established the importance of global tropospheric wind measurements for large scale improvements in numerical weather prediction. In addition, global wind measurements provide data that are fundamental to the understanding and prediction of global climate change. These tasks are closely linked with the goals of the NASA Earth Science Enterprise and Global Climate Change programs. NASA Goddard has been actively involved in the development of direct detection Doppler lidar methods and technologies to meet the wind observing needs of the atmospheric science community. In this paper we describe a recently developed prototype wind lidar system using a direct detection Doppler technique for measuring wind profiles from the surface through the troposphere. This system uses a pulsed ND:YAG laser operating at 1064 nm as the transmitter. The laser pulse is directed to the atmosphere using a 40 cm diameter scan mirror. The portion of the laser energy backscattered from aerosols and molecules is collected by a 40 cm diameter telescope and coupled via fiber optics into the Doppler receiver. Single photon counting APD's are used to detect the atmospheric backscattered signal. The principle element of the receiver is a dual bandpass tunable Fabry Perot etalon which analyzes the Doppler shift of the incoming laser signal using the double edge technique. The double edge technique uses two high resolution optical filters having bandpasses offset relative to one another such that the 'edge' of the first filter's transmission function crosses that of the second at the half power point. The outgoing laser frequency is located approximately at the crossover point. Due to the opposite going slopes of the edges, a Doppler shift in the atmospheric backscattered laser frequency produces a positive change in signal for one filter and a negative change in the second filter. Taking the ratio of the two edge channel signals yields a result which is directly proportional to the

  19. Terminal Doppler weather radar

    NASA Astrophysics Data System (ADS)

    Michelson, M.; Shrader, W. W.; Wieler, J. G.

    1990-02-01

    The terminal Doppler weather radar (TDWR) system, now under development, will provide automatic detection of microbursts and low-level wind shear. This paper discusses the TDWR performance parameters and describes its structural elements, including the antenna subsystem, the transmitter, the receiver/exciter, the digital signal processor, and the radar product generator/remote monitoring subsystem. Attention is also given to the processes of the base data formation, point target removal, signal-to-noise thresholding, and velocity de-aliasing and to the TDWR algorithms and displays. A schematic diagram of the TDWR system is presented.

  20. Normal Echocardiographic Measurements in a Korean Population Study: Part II. Doppler and Tissue Doppler Imaging

    PubMed Central

    Choi, Jin-Oh; Shin, Mi-Seung; Kim, Mi-Jeong; Jung, Hae Ok; Park, Jeong Rang; Sohn, Il Suk; Kim, Hyungseop; Park, Seong-Mi; Yoo, Nam Jin; Choi, Jung Hyun; Kim, Hyung-Kwan; Cho, Goo-Yeong; Lee, Mi-Rae; Park, Jin-Sun; Shim, Chi Young; Kim, Dae-Hee; Shin, Dae-Hee; Shin, Gil Ja; Shin, Sung Hee; Kim, Kye Hun; Park, Jae-Hyeong; Lee, Sang Yeub; Kim, Woo-Shik

    2016-01-01

    Background Hemodynamic and functional evaluation with Doppler and tissue Doppler study as a part of comprehensive echocardiography is essential but normal reference values have never been reported from Korean normal population especially according to age and sex. Methods Using Normal echOcaRdiographic Measurements in a KoreAn popuLation study subjects, we obtained normal reference values for Doppler and tissue Doppler echocardiography including tricuspid annular velocities according to current guidelines and compared values according to gender and age groups. Results Mitral early diastolic (E) and late diastolic (A) velocity as well as E/A ratio were significantly higher in women compared to those in men. Conversely, mitral peak systolic and late diastolic annular velocity in both septal and lateral mitral annulus were significantly lower in women compared to those in men. However, there were no significant differences in both septal and lateral mitral early diastolic annular (e') velocity between men and women. In both men and women, mitral E velocity and its deceleration time as well as both E/A and E/e' ratio considerably increased with age. There were no significant differences in tricuspid inflow velocities and tricuspid lateral annular velocities between men and women except e' velocity, which was significantly higher in women compared to that in men. However, changes in both tricuspid inflow and lateral annular velocities according to age were similar to those in mitral velocities. Conclusion Since there were significant differences in Doppler and tissue Doppler echocardiographic variables between men and women and changes according to age were even more considerable in both gender groups, normal Doppler echocardiographic values should be differentially applied based on age and sex. PMID:27358707

  1. The Effect of Molecular Conformation on the Accuracy of Theoretical (1)H and (13)C Chemical Shifts Calculated by Ab Initio Methods for Metabolic Mixture Analysis.

    PubMed

    Chikayama, Eisuke; Shimbo, Yudai; Komatsu, Keiko; Kikuchi, Jun

    2016-04-14

    NMR spectroscopy is a powerful method for analyzing metabolic mixtures. The information obtained from an NMR spectrum is in the form of physical parameters, such as chemical shifts, and construction of databases for many metabolites will be useful for data interpretation. To increase the accuracy of theoretical chemical shifts for development of a database for a variety of metabolites, the effects of sets of conformations (structural ensembles) and the levels of theory on computations of theoretical chemical shifts were systematically investigated for a set of 29 small molecules in the present study. For each of the 29 compounds, 101 structures were generated by classical molecular dynamics at 298.15 K, and then theoretical chemical shifts for 164 (1)H and 123 (13)C atoms were calculated by ab initio quantum chemical methods. Six levels of theory were used by pairing Hartree-Fock, B3LYP (density functional theory), or second order Møller-Plesset perturbation with 6-31G or aug-cc-pVDZ basis set. The six average fluctuations in the (1)H chemical shift were ±0.63, ± 0.59, ± 0.70, ± 0.62, ± 0.75, and ±0.66 ppm for the structural ensembles, and the six average errors were ±0.34, ± 0.27, ± 0.32, ± 0.25, ± 0.32, and ±0.25 ppm. The results showed that chemical shift fluctuations with changes in the conformation because of molecular motion were larger than the differences between computed and experimental chemical shifts for all six levels of theory. In conclusion, selection of an appropriate structural ensemble should be performed before theoretical chemical shift calculations for development of an accurate database for a variety of metabolites. PMID:26963288

  2. Doppler Shifts in Active Region Moss Using SOHO/SUMER

    NASA Astrophysics Data System (ADS)

    Winebarger, Amy; Tripathi, Durgesh; Mason, Helen E.; Del Zanna, Giulio

    2013-04-01

    The velocity of the plasma at the footpoint of hot loops in active region cores can be used to discriminate between different heating frequencies. Velocities on the order of a few kilometers per second would indicate low-frequency heating on sub-resolution strands, while velocities close to zero would indicate high-frequency (steady) heating. To discriminate between these two values requires accurate velocity measurements; previous velocity measurements suffer from large uncertainties, mainly due to the lack of an absolute wavelength reference scale. In this paper, we determine the velocity in the loop footpoints using observations from Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on Solar and Heliospheric Observatory. We use neutral spectral lines to determine the wavelength scale of the observations with an uncertainty in the absolute velocity of <3.5 km s-1 and co-aligned Transition Region and Coronal Explorer (TRACE) images to identify footpoint regions. We studied three different active regions and found average redshifts in the Ne VIII 770 Å emission line (formed at 6 × 105 K) of 5.17 ± 5.37 km s-1 and average redshifts in the C IV 1548 and 1550 Å emission lines (formed at 1 × 105 K) of 13.94 ± 4.93 km s-1 and 14.91 ± 6.09 km s-1, respectively. We find no correlation between the brightness in the spectral line and the measured velocity, nor do we find correlation between the Ne VIII and C IV velocities measured co-spatially and co-temporally. SUMER scanned two of the active regions twice; in those active regions we find positive correlation between the co-spatial velocities measured during the first and second scans. These results provide definitive and quantitative measurements for comparisons with simulations of different coronal heating mechanisms.

  3. Holographic motion picture camera with Doppler shift compensation

    NASA Technical Reports Server (NTRS)

    Kurtz, R. L. (Inventor)

    1976-01-01

    A holographic motion picture camera is reported for producing three dimensional images by employing an elliptical optical system. There is provided in one of the beam paths (the object or reference beam path) a motion compensator which enables the camera to photograph faster moving objects.

  4. Imaging doppler lidar for wind turbine wake profiling

    DOEpatents

    Bossert, David J.

    2015-11-19

    An imaging Doppler lidar (IDL) enables the measurement of the velocity distribution of a large volume, in parallel, and at high spatial resolution in the wake of a wind turbine. Because the IDL is non-scanning, it can be orders of magnitude faster than conventional coherent lidar approaches. Scattering can be obtained from naturally occurring aerosol particles. Furthermore, the wind velocity can be measured directly from Doppler shifts of the laser light, so the measurement can be accomplished at large standoff and at wide fields-of-view.

  5. The Rossiter-McLaughlin effect of planets transiting M-dwarfs, and its impact on planet detection in Doppler surveys

    NASA Astrophysics Data System (ADS)

    Cloutier, Ryan; Triaud, Amaury H. M. J.; Menou, Kristen

    2015-12-01

    A major endeavour in recent exoplanetary science is to detect potentially habitable, Earth-like planets around nearby stars. The upcoming SPIRou (Le SpectroPolarimètre Infra-Rouge) Legacy Survey is one such initiative and is optimized for the detection of such exoplanets around cool M-dwarfs via the radial velocity method. If a planetary transit occurs, radial velocity observations made in-transit will be subject to an anomalous signal due to the occultation of the differentially Doppler shifted stellar limbs; the so-called Rossiter-McLaughlin (RM) effect. Using the SPIRou Legacy Survey as a test case, we assess the impact of the RM effect on unevenly sampled Doppler survey data. Firstly, the stellar spectra taken during a Doppler survey, along with an assumed planetary mass-radius relationship, can be used to estimate the likelihood of a planetary transit. This is useful for target-selection of stars with potentially transiting exoplanets. However, if not properly accounted for in models of the stellar Doppler shift, the anomalous RM effect can result in 20-30% loss in planet detection rate. This significant loss can be easily remedied by our proposed simple process of iteratively re-sampling the timeseries and searching for periodicities. For the subset of the anticipated SPIRou planet population that is hidden by the RM effect, our algorithm is capable of recovering planets with the same efficiency as in the absence of the RM effect thus negating its effect.

  6. Pre-coding method and apparatus for multiple source or time-shifted single source data and corresponding inverse post-decoding method and apparatus

    NASA Technical Reports Server (NTRS)

    Yeh, Pen-Shu (Inventor)

    1997-01-01

    A pre-coding method and device for improving data compression performance by removing correlation between a first original data set and a second original data set, each having M members, respectively. The pre-coding method produces a compression-efficiency-enhancing double-difference data set. The method and device produce a double-difference data set, i.e., an adjacent-delta calculation performed on a cross-delta data set or a cross-delta calculation performed on two adjacent-delta data sets, from either one of (1) two adjacent spectral bands coming from two discrete sources, respectively, or (2) two time-shifted data sets coming from a single source. The resulting double-difference data set is then coded using either a distortionless data encoding scheme (entropy encoding) or a lossy data compression scheme. Also, a post-decoding method and device for recovering a second original data set having been represented by such a double-difference data set.

  7. Pre-coding method and apparatus for multiple source or time-shifted single source data and corresponding inverse post-decoding method and apparatus

    NASA Technical Reports Server (NTRS)

    Yeh, Pen-Shu (Inventor)

    1998-01-01

    A pre-coding method and device for improving data compression performance by removing correlation between a first original data set and a second original data set, each having M members, respectively. The pre-coding method produces a compression-efficiency-enhancing double-difference data set. The method and device produce a double-difference data set, i.e., an adjacent-delta calculation performed on a cross-delta data set or a cross-delta calculation performed on two adjacent-delta data sets, from either one of (1) two adjacent spectral bands coming from two discrete sources, respectively, or (2) two time-shifted data sets coming from a single source. The resulting double-difference data set is then coded using either a distortionless data encoding scheme (entropy encoding) or a lossy data compression scheme. Also, a post-decoding method and device for recovering a second original data set having been represented by such a double-difference data set.

  8. Doing the Doppler. How to Drive This Concept Home.

    ERIC Educational Resources Information Center

    Koser, John F.

    1990-01-01

    An outdoor activity that demonstrates the Doppler effect is described. Class predictions are verified by actual involvement in collecting data. Presented is a method of analyzing data. Safety concerns are discussed. (KR)

  9. Validity of the vertical tube-shift method in determining the relationship between the mandibular third molar roots and the inferior alveolar nerve canal

    PubMed Central

    2015-01-01

    Objectives To assess the validity of the vertical tube-shift method using intraoral periapical radiography (IOPAR) for determining the relationship between the mandibular third molar roots and the inferior alveolar nerve (IAN) canal in comparison with cone-beam computed tomography (CBCT). Materials and Methods Fifty impacted mandibular third molars were analyzed using the IOPAR vertical tube-shift method and CBCT. The relationship of the IAN canal to the impacted mandibular third molar was recorded as buccal, lingual or in line with the apex and was compared with CBCT findings. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the vertical tube-shift method in depicting the relationship (buccal/lingual/in line with the apex) of the IAN canal to the third molar root apex was calculated. Results The sensitivity and specificity PPV and NPV of the IOPAR vertical tube-shift technique was found to be highest for a lingual relationship (100%) followed by buccal (94.4%, 92.3%, 97.1%, and 85.7%) and in line with the apex relationship (88.9%, 95.0%, 80.0%, and 97.4%) of the IAN canal with the third molar root apex, respectively. A statistically significant association was observed between the IOPAR vertical tube-shift method and the CBCT with a P-value <0.01. Conclusion The vertical tube-shift method can be used as an effective diagnostic tool in assessing the relationship of the IAN canal to the third molar root apex with high sensitivity, specificity, PPV, and NPV. PMID:25922817

  10. ANL Doppler flowmeter

    NASA Astrophysics Data System (ADS)

    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.

  11. Method and System for Producing Images of an Object

    NASA Technical Reports Server (NTRS)

    Katzberg, Stephen J. (Inventor); Garrison, James L., Jr. (Inventor)

    1999-01-01

    A method and system are provided to produce images of an object. A receiving station is positioned in view of a range-coded signal emitting satellite and the object. The receiving station is sensitive to direct transmission of the range-coded signal and reflections of the range-coded signal from the object. Both range from the receiving station to the object and a Doppler frequency shift history between the receiving station and the object is determined using the direct transmission and reflections of the range-coded signal. An image is formed using the two-dimensional record provided by the range and the Doppler frequency shift history.

  12. Fluid Shifts

    NASA Technical Reports Server (NTRS)

    Stenger, Michael B.; Hargens, Alan R.; Dulchavsky, Scott A.; Ebert, Douglas J.; Lee, Stuart M. C.; Laurie, Steven S.; Garcia, Kathleen M.; Sargsyan, Ashot E.; Martin, David S.; Liu, John; Macias, Brandon R.; Arbeille, Philippe; Danielson, Richard; Chang, Douglas; Gunga, Hanns-Christian; Johnston, Smith L.; Westby, Christian M.; Ploutz-Snyder, Robert J.; Smith, Scott M.

    2016-01-01

    We hypothesize that microgravity-induced cephalad fluid shifts elevate intracranial pressure (ICP) and contribute to VIIP. We will test this hypothesis and a possible countermeasure in ISS astronauts.

  13. Use of Doppler ultrasound for non-invasive urodynamic diagnosis

    PubMed Central

    Ozawa, Hideo; Watanabe, Toyohiko; Uematsu, Katsutoshi; Sasaki, Katsumi; Inoue, Miyabi; Kumon, Hiromi

    2009-01-01

    Objectives: A totally non-invasive transperineal urodynamic technique using Doppler ultrasonography has been developed. Methods: Since normal urine does not have blood cells, urine was thought not to produce the Doppler effects. However, basic studies confirmed that the decrease of pressure at high velocity (Bernouilli effect) caused dissolved gas to form microbubbles, which are detected by Doppler ultrasonography. Subjects sat and the probe was advanced via remote control to achieve gentle contact with the perineal skin. The digital uroflow data signals and the color Doppler ultrasound video images were processed on a personal computer. The flow-velocity curves from two sites; the distal prostatic urethra just above the external sphincter (V1) and the sphincteric urethra (V2) were plotted against time. The parameters of both the pressure-flow studies and the Doppler ultrasound urodynamic studies were compared in men who had various degrees of obstruction. Results: Functional cross-sectional area at prostatic urethra (A1), calculated by Qmax/V1, was lower in the group of bladder outlet obstruction (BOO) vs. control group. Velocity ratio (VR), which was calculated by V1/V2, was the parameter having the best correlation with BOO index, though A1 had a similar correlation. This method is viable to diagnose the degree of BOO. Conclusions: The development of non-invasive Doppler ultrasound videourodynamics (Doppler UDS) will dramatically expand the information on voiding function. PMID:19468440

  14. Doppler Beats or Interference Fringes?

    ERIC Educational Resources Information Center

    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;…

  15. Theoretical and experimental signal-to-noise ratio assessment in new direction sensing continuous-wave Doppler lidar

    NASA Astrophysics Data System (ADS)

    Tegtmeier Pedersen, A.; Abari, C. F.; Mann, J.; Mikkelsen, T.

    2014-06-01

    A new direction sensing continuous-wave Doppler lidar based on an image-reject homodyne receiver has recently been demonstrated at DTU Wind Energy, Technical University of Denmark. In this contribution we analyse the signal-to-noise ratio resulting from two different data processing methods both leading to the direction sensing capability. It is found that using the auto spectrum of the complex signal to determine the wind speed leads to a signal-to-noise ratio equivalent to that of a standard self-heterodyne receiver. Using the imaginary part of the cross spectrum to estimate the Doppler shift has the benefit of a zero-mean background spectrum, but comes at the expense of a decrease in the signal-to noise ratio by a factor of √2.

  16. Interferometric millimeter wave and THz wave doppler radar

    DOEpatents

    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. Doppler ultrasound signal denoising based on wavelet frames.

    PubMed

    Zhang, Y; Wang, Y; Wang, W; Liu, B

    2001-05-01

    A novel approach was proposed to denoise the Doppler ultrasound signal. Using this method, wavelet coefficients of the Doppler signal at multiple scales were first obtained using the discrete wavelet frame analysis. Then, a soft thresholding-based denoising algorithm was employed to deal with these coefficients to get the denoised signal. In the simulation experiments, the SNR improvements and the maximum frequency estimation precision were studied for the denoised signal. From the simulation and clinical studies, it was concluded that the performance of this discrete wavelet frame (DWF) approach is higher than that of the standard (critically sampled) wavelet transform (DWT) for the Doppler ultrasound signal denoising. PMID:11381694

  18. "Having to Shift Everything We've Learned to the Side": Expanding Research Methods Taught in Psychology to Incorporate Qualitative Methods.

    PubMed

    Roberts, Lynne D; Castell, Emily

    2016-01-01

    In Australia the tradition of conducting quantitative psychological research within a positivist framework has been challenged, with calls made for the inclusion of the full range of qualitative and quantitative methodologies within the undergraduate psychology curriculum. Despite this, the undergraduate psychology curriculum in most Australian universities retains a strong focus on teaching quantitative research methods. Limited research has examined attitudes toward qualitative research held by undergraduate psychology students taught within a positivist framework, and whether these attitudes are malleable and can be changed through teaching qualitative methodologies. Previous research has suggested that students from strong quantitative backgrounds experience some cognitive dissonance and greater difficulties in learning qualitative methods. In this article we examine 3rd year undergraduate psychology students' attitudes to qualitative research prior to commencing and upon completion of a qualitative research unit. All students had previously completed two 13 weeks units of study in quantitative research methods. At Time 1, 63 students (84.1% female) completed online surveys comprising attitudinal measures. Key themes to emerge from student comments were that qualitative research was seen as an alternative approach, representing a paradigmatic shift that was construed by some students advantageous for meeting future professional and educative goals. Quantitative measures of attitudes to qualitative research were associated with general attitudes toward research, and psychology-specific epistemological beliefs. Changes in attitudes following completion of the qualitative research methods unit were in the hypothesized direction, but non-significant (small effect sizes). The findings increase our understanding of psychology students' attitudes toward qualitative research and inform our recommendations for teaching research methods within the undergraduate

  19. “Having to Shift Everything We’ve Learned to the Side”: Expanding Research Methods Taught in Psychology to Incorporate Qualitative Methods

    PubMed Central

    Roberts, Lynne D.; Castell, Emily

    2016-01-01

    In Australia the tradition of conducting quantitative psychological research within a positivist framework has been challenged, with calls made for the inclusion of the full range of qualitative and quantitative methodologies within the undergraduate psychology curriculum. Despite this, the undergraduate psychology curriculum in most Australian universities retains a strong focus on teaching quantitative research methods. Limited research has examined attitudes toward qualitative research held by undergraduate psychology students taught within a positivist framework, and whether these attitudes are malleable and can be changed through teaching qualitative methodologies. Previous research has suggested that students from strong quantitative backgrounds experience some cognitive dissonance and greater difficulties in learning qualitative methods. In this article we examine 3rd year undergraduate psychology students’ attitudes to qualitative research prior to commencing and upon completion of a qualitative research unit. All students had previously completed two 13 weeks units of study in quantitative research methods. At Time 1, 63 students (84.1% female) completed online surveys comprising attitudinal measures. Key themes to emerge from student comments were that qualitative research was seen as an alternative approach, representing a paradigmatic shift that was construed by some students advantageous for meeting future professional and educative goals. Quantitative measures of attitudes to qualitative research were associated with general attitudes toward research, and psychology-specific epistemological beliefs. Changes in attitudes following completion of the qualitative research methods unit were in the hypothesized direction, but non-significant (small effect sizes). The findings increase our understanding of psychology students’ attitudes toward qualitative research and inform our recommendations for teaching research methods within the undergraduate

  20. Accuracy of Calculated Chemical Shifts in Carbon 1s Ionization Energies from Single-Reference ab Initio Methods and Density Functional Theory.

    PubMed

    Holme, Alf; Børve, Knut J; Sæthre, Leif J; Thomas, T Darrah

    2011-12-13

    A database of 77 adiabatic carbon 1s ionization energies has been prepared, covering linear and cyclic alkanes and alkenes, linear alkynes, and methyl- or fluoro-substituted benzenes. Individual entries are believed to carry uncertainties of less than 30 meV in ionization energies and less than 20 meV for shifts in ionization energies. The database provides an unprecedented opportunity for assessing the accuracy of theoretical schemes for computing inner-shell ionization energies and their corresponding chemical shifts. Chemical shifts in carbon 1s ionization energies have been computed for all molecules in the database using Hartree-Fock, Møller-Plesset (MP) many-body perturbation theory of order 2 and 3 as well as various approximations to full MP4, and the coupled-cluster approximation with single- and double-excitation operators (CCSD) and also including a perturbational estimate of the energy effect of triple-excitation operators (CCSD(T)). Moreover, a wide range of contemporary density functional theory (DFT) methods are also evaluated with respect to computing experimental shifts in C1s ionization energies. Whereas the top ab initio methods reproduce the observed shifts almost to within the experimental uncertainty, even the best-performing DFT approaches meet with twice the root-mean-squared error and thrice the maximum error compared to CCSD(T). However, a number of different density energy functionals still afford sufficient accuracy to become tools in the analysis of complex C1s photoelectron spectra. PMID:26598356

  1. Attenuated Vector Tomography -- An Approach to Image Flow Vector Fields with Doppler Ultrasonic Imaging

    SciTech Connect

    Huang, Qiu; Peng, Qiyu; Huang, Bin; Cheryauka, Arvi; Gullberg, Grant T.

    2008-05-15

    The measurement of flow obtained using continuous wave Doppler ultrasound is formulated as a directional projection of a flow vector field. When a continuous ultrasound wave bounces against a flowing particle, a signal is backscattered. This signal obtains a Doppler frequency shift proportional to the speed of the particle along the ultrasound beam. This occurs for each particle along the beam, giving rise to a Doppler velocity spectrum. The first moment of the spectrum provides the directional projection of the flow along theultrasound beam. Signals reflected from points further away from the detector will have lower amplitude than signals reflected from points closer to the detector. The effect is very much akin to that modeled by the attenuated Radon transform in emission computed tomography.A least-squares method was adopted to reconstruct a 2D vector field from directional projection measurements. Attenuated projections of only the longitudinal projections of the vector field were simulated. The components of the vector field were reconstructed using the gradient algorithm to minimize a least-squares criterion. This result was compared with the reconstruction of longitudinal projections of the vector field without attenuation. Ifattenuation is known, the algorithm was able to accurately reconstruct both components of the full vector field from only one set of directional projection measurements. A better reconstruction was obtained with attenuation than without attenuation implying that attenuation provides important information for the reconstruction of flow vector fields.This confirms previous work where we showed that knowledge of the attenuation distribution helps in the reconstruction of MRI diffusion tensor fields from fewer than the required measurements. In the application of ultrasound the attenuation distribution is obtained with pulse wave transmission computed tomography and flow information is obtained with continuous wave Doppler.

  2. Duplex Doppler ultrasound study of the temporomandibular joint

    PubMed Central

    Stagnitti, A.; Marini, A.; Impara, L.; Drudi, F.M.; Lo mele, L.; Lillo Odoardi, G.

    2012-01-01

    Introduction The anatomy and physiology of the temporomandibular joint can be studied clinically and by diagnostic imaging. Magnetic resonance imaging (MRI), radiography (X-ray) and computed tomography (CT) have thus for many years contributed to the study of the kinetics in the mandibular condyle. However, also duplex Doppler ultrasound (US) examination is widely used in the study of structures during movement, particularly vascular structures. Materials and methods A total of 30 patients were referred by the Department of Orthodontics to the Department of Radiological, Oncological and Pathological Sciences, University of Rome “La Sapienza”. All patients underwent duplex Doppler ultrasound (US) examination of the temporomandibular joint using Toshiba APLIO SSA-770A equipment and duplex Doppler multi-display technique, which allows simultaneous display of US images and color Doppler signals. A linear phased array probe with crystal elements was used operating at a basic frequency of 6 MHz during pulsed Doppler spectral analysis and 7.5 MHz during US imaging. Results In normal patients a regular alternation in the spectral Doppler waveforms was obtained, while in patients with temporomandibular joint meniscus dysfunction there was no regularity in the sum of the Fourier series with an unsteady waveform pattern related to irregular movements of the temporomandibular joint. Conclusions In all cases duplex Doppler US examination proved able to differentiate between normal and pathological patients and among the latter this technique permitted identification of the most significant aspects of the dysfunctional diseases. PMID:23397016

  3. Fragment-based {sup 13}C nuclear magnetic resonance chemical shift predictions in molecular crystals: An alternative to planewave methods

    SciTech Connect

    Hartman, Joshua D.; Beran, Gregory J. O.; Monaco, Stephen; Schatschneider, Bohdan

    2015-09-14

    We assess the quality of fragment-based ab initio isotropic {sup 13}C chemical shift predictions for a collection of 25 molecular crystals with eight different density functionals. We explore the relative performance of cluster, two-body fragment, combined cluster/fragment, and the planewave gauge-including projector augmented wave (GIPAW) models relative to experiment. When electrostatic embedding is employed to capture many-body polarization effects, the simple and computationally inexpensive two-body fragment model predicts both isotropic {sup 13}C chemical shifts and the chemical shielding tensors as well as both cluster models and the GIPAW approach. Unlike the GIPAW approach, hybrid density functionals can be used readily in a fragment model, and all four hybrid functionals tested here (PBE0, B3LYP, B3PW91, and B97-2) predict chemical shifts in noticeably better agreement with experiment than the four generalized gradient approximation (GGA) functionals considered (PBE, OPBE, BLYP, and BP86). A set of recommended linear regression parameters for mapping between calculated chemical shieldings and observed chemical shifts are provided based on these benchmark calculations. Statistical cross-validation procedures are used to demonstrate the robustness of these fits.

  4. Influence of speckle effect on doppler velocity measurement

    NASA Astrophysics Data System (ADS)

    Zheng, Zheng; Changming, Zhao; Haiyang, Zhang; Suhui, Yang; Dehua, Zhang; Xingyuan, Zheng; Hongzhi, Yang

    2016-06-01

    In a coherent Lidar system, velocity measurement of a target is achieved by measuring Doppler frequency shift between the echo and local oscillator (LO) signals. The measurement accuracy is proportional to the spectrum width of Doppler signal. Actually, the speckle effect caused by the scattering of laser from a target will broaden the Doppler signal's spectrum and bring uncertainty to the velocity measurement. In this paper, a theoretical model is proposed to predict the broadening of Doppler spectrum with respect to different target's surface and motion parameters. The velocity measurement uncertainty caused by the broadening of spectrum is analyzed. Based on the analysis, we design a coherent Lidar system to measure the velocity of the targets with different surface roughness and transverse velocities. The experimental results are in good agreement with theoretical analysis. It is found that the target's surface roughness and transverse velocity can significantly affect the spectrum width of Doppler signal. With the increase of surface roughness and transverse velocity, the measurement accuracy becomes worse. However, the influence of surface roughness becomes weaker when the spot size of laser beam on the target is smaller.

  5. Results of the international ionospheric Doppler sounder network

    NASA Astrophysics Data System (ADS)

    Lastovicka, Jan; Chum, Jaroslav

    2016-07-01

    This paper summarizes main recent results reached by the Czech-lead international network of ionospheric Doppler sounders. The network consists of Doppler sounders in the western half of Czechia (5 measuring paths, 3 frequencies with central receivers in Prague), northern Taiwan (3 transmitters, two separated receivers, 1 frequency), and three similar systems (3 measuring paths with 1 receiver and 1 frequency) in Tucuman (north-western Argentina), Hermanus (the southernmost South Africa) and Luisville (northern South Africa). Three main areas of research have been (1) statistical properties of gravity waves, (2) ionospheric effects of earthquakes, and (3) low latitude/equatorial phenomena. Some results: (1) the theoretically expected dominance of gravity wave propagation against wind has been confirmed; (2) impact of the Tohoku 2001 M9.0 earthquake was registered in the ionosphere over the Czech Republic as long-period infrasound on the distance of about 9000 km from epicenter; analysis of ionospheric infrasound excited by the Nepal 2015 M7.8 earthquake observed by the Czech and Taiwan Doppler sounders showed that the intensity of ionospheric signal is significantly height dependent and that the Doppler shift depends not only on the advection (up and down motion) of the reflecting layer but also on the compression/rarefaction of the electron gas; (3) spread F structures observed by Doppler sounders in Tucuman and Taiwan (both under the crest of equatorial ionization anomaly) provide results consistent with S4 scintillation data and with previous optical, GPS and satellite measurements.

  6. Doppler ultrasound--basics revisited.

    PubMed

    Eagle, Mary

    Palpation of pedal pulses alone is known to be an unreliable indicator for the presence of arterial disease. Using portable Doppler ultrasound to measure the resting ankle brachial pressure index is superior to palpation of peripheral pulses as an assessment of the adequacy pf the arterial supply in the lower limb. Revisiting basics, this article aims to aid the clinician to understand and perform hand-held Doppler ultrasound effectively while involving the client or patient in the process. The author describes the basics of Doppler ultrasound, how to select correct equipment for the process, and interpretation of results to further enhance clinicians' knowledge. PMID:16835512

  7. Digital Doppler measurement with spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.; Hinedi, Sami M.; Labelle, Remi C.; Bevan, Roland P.; Del Castillo, Hector M.; Chong, Dwayne C.

    1991-01-01

    Digital and analog phase-locked loop (PLL) receivers were operated in parallel, each tracking the residual carrier from a spacecraft. The PLL tracked the downlink carrier and measured its instantaneous phase. This information, combined with a knowledge of the uplink carrier and the transponder ratio, permitted the computation of a Doppler observable. In this way, two separate Doppler measurements were obtained for one observation window. The two receivers agreed on the magnitude of the Doppler effect to within 1 mHz. There was less jitter on the data from the digital receiver. This was due to its smaller noise bandwidth. The demonstration and its results are described.

  8. Airborne microwave Doppler measurements of ocean wave directional spectra

    NASA Technical Reports Server (NTRS)

    Plant, W. J.; Keller, W. C.; Reeves, A. B.; Uliana, E. A.; Johnson, J. W.

    1987-01-01

    A technique is presented for measuring ocean wave directional spectra from aircraft using microwave Doppler radar. The technique involves backscattering coherent microwave radiation from a patch of sea surface which is small compared to dominant ocean wavelengths in the antenna look direction, and large compared to these lengths in the perpendicular (azimuthal) direction. The mean Doppler shift of the return signal measured over short time intervals is proportional to the mean sea surface velocity of the illuminated patch. Variable sea surface velocities induced by wave motion therefore produce time-varying Doppler shifts in the received signal. The large azimuthal dimension of the patch implies that these variations must be produced by surface waves traveling near the horizontal antenna look direction thus allowing determination of the direction of wave travel. Linear wave theory is used to convert the measured velocities into ocean wave spectral densities. Spectra measured simultaneously with this technique and two laser profilometers, and nearly simultaneous with this technique and two laser profilometers, and nearly simultaneous with a surface buoy, are presented. Applications and limitations of this airborne Doppler technique are discussed.

  9. Shifting scintillator neutron detector

    SciTech Connect

    Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

    2014-03-04

    Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

  10. Doppler velocity measurements from large and small arteries of mice

    PubMed Central

    Reddy, Anilkumar K.; Madala, Sridhar; Entman, Mark L.; Michael, Lloyd H.; Taffet, George E.

    2011-01-01

    With the growth of genetic engineering, mice have become increasingly common as models of human diseases, and this has stimulated the development of techniques to assess the murine cardiovascular system. Our group has developed nonimaging and dedicated Doppler techniques for measuring blood velocity in the large and small peripheral arteries of anesthetized mice. We translated technology originally designed for human vessels for use in smaller mouse vessels at higher heart rates by using higher ultrasonic frequencies, smaller transducers, and higher-speed signal processing. With these methods one can measure cardiac filling and ejection velocities, velocity pulse arrival times for determining pulse wave velocity, peripheral blood velocity and vessel wall motion waveforms, jet velocities for the calculation of the pressure drop across stenoses, and left main coronary velocity for the estimation of coronary flow reserve. These noninvasive methods are convenient and easy to apply, but care must be taken in interpreting measurements due to Doppler sample volume size and angle of incidence. Doppler methods have been used to characterize and evaluate numerous cardiovascular phenotypes in mice and have been particularly useful in evaluating the cardiac and vascular remodeling that occur following transverse aortic constriction. Although duplex ultrasonic echo-Doppler instruments are being applied to mice, dedicated Doppler systems are more suitable for some applications. The magnitudes and waveforms of blood velocities from both cardiac and peripheral sites are similar in mice and humans, such that much of what is learned using Doppler technology in mice may be translated back to humans. PMID:21572013

  11. The experimental study on Doppler echo signals with different scattering surfaces for velocity measurement

    NASA Astrophysics Data System (ADS)

    Wang, Leng-ping; Feng, Di; Ou, Pan; Yang, De-zhao

    2011-06-01

    Laser Doppler velocimetry has the ability to measure speed and surface vibrations non-intrusively with high precision. In this study the Doppler spectrum shift and spectrum broadening of echo signals by moving targets are investigated. The interaction between moving object and the laser beam of laser Doppler velocimetry have been described by varying rotating velocity, the angular velocity, distance and incident facula. By using different scattering surfaces, such as Polytetrafluoroethylene (PTFE) and sandpaper with different grain sizes, the characteristics of echo signals' Doppler spectra have been studied experimentally in detail. The results show that Doppler spectrum distribution is changed with different scattering surfaces. Meanwhile, in order to get a high measuring accuracy, the moving object's scattering characteristics must be considered carefully.

  12. Evaluation of meteorological airborne Doppler radar

    NASA Technical Reports Server (NTRS)

    Hildebrand, P. H.; Mueller, C. K.

    1984-01-01

    This paper will discuss the capabilities of airborne Doppler radar for atmospheric sciences research. The evaluation is based on airborne and ground based Doppler radar observations of convective storms. The capability of airborne Doppler radar to measure horizontal and vertical air motions is evaluated. Airborne Doppler radar is shown to be a viable tool for atmospheric sciences research.

  13. Method of Phase and Amplitude Modulation/Demodulation Using Datapages with Embedded Phase-Shift for Holographic Data Storage

    NASA Astrophysics Data System (ADS)

    Bunsen, Masatoshi; Umetsu, Shuhei; Takabayashi, Masanori; Okamoto, Atsushi

    2013-09-01

    A technique for the phase and amplitude detection of object beams with multivalued phase and amplitude modulation is proposed for holographic storage systems. Generally, the spatial distribution of the complex amplitude of the object beam can be precisely detected by phase-shifting interferometric measurements in which the phase of the reference wave for interferometry is temporally or spatially changed in the datapage retrieval process. On the other hand, our technique allows fast, accurate, and feasible phase and amplitude demodulations by preliminary embedding phase shift into the phase signal of the datapage during recording. This technique will significantly improve the data transfer rate and vibration tolerance of the holographic storage system because the complex amplitudes of the object beam carrying datapages can be detected by single-shot image capturing. The optical system for datapage replay will also be simplified because there is no need to use any phase-shifting device during data retrieval. The single-shot detection of the phase-modulated datapage is experimentally demonstrated.

  14. Dispersion corrections to the Gaussian profile describing the Doppler broadening of spectral lines

    NASA Astrophysics Data System (ADS)

    Wójtewicz, S.; Wcisło, P.; Lisak, D.; Ciuryło, R.

    2016-04-01

    A dispersionally corrected Gaussian profile describing Doppler-broadened spectral line shapes is presented. Proposed corrections include the frequency dependence of the Doppler shifting caused by dispersion as well as by light frequency variation over the whole spectral line shape. It is shown that the frequency dependence of the Doppler shifting can have a non-negligible influence on the line-shape model and can affect the line shape even at the relative level of 10-5. Moreover, this effect also influences the determination of the line position at the level of kilohertz. Finally, the impact of the presented results on the Doppler width thermometry and precise molecular spectroscopy for fundamental studies is emphasized.

  15. Dual-Doppler Feasibility Study

    NASA Technical Reports Server (NTRS)

    Huddleston, Lisa L.

    2012-01-01

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

  16. Numerical studies of HF Doppler variations caused by ionospheric disturbances

    NASA Astrophysics Data System (ADS)

    Takefu, M.; Hiroshige, N.

    HF Doppler variations caused by ionospheric disturbances are studied using an ionosphere model containing sinusoidal traveling electron density fluctuations. The present study uses a more realistic ionosphere model and a more accurate numerical method than previous works using corrugated specular reflector models. The study gives a clue to estimate the TID-associated fluctuations of ionospheric electron density by means of HF Doppler measurements. It is shown that some kinds of characteristic HF Doppler traces result depending on the wavelength of the disturbance and its traveling direction. Numerical results suggest that more or less 5 percent of the background electron density can explain most of the quasi-periodic variations on the observed HF Doppler records.

  17. Doppler ultrasound studies in pelvic inflammatory disease.

    PubMed

    Tinkanen, H; Kujansuu, E

    1992-01-01

    Ten women with tubo-ovarian abscess caused by pelvic inflammatory disease (PID) were investigated by transvaginal Doppler ultrasound during the acute and healing phases of the infection. The pulsatility index (PI) of the uterine arteries was measured and compared with the values obtained from 19 healthy women. Each control patient was investigated three times during a single menstrual cycle. In PID patients, the PI values were significantly lower than in controls in the same phase of the menstrual cycle. When C-reactive protein was > 50, the PI values were lowest and reverted to normal values when the infection subsided. In a case of chronic infection, the PI did not rise to normal despite normal infection parameters. Doppler ultrasound seems to offer a new method of assessing PID. PMID:1487185

  18. Mathematical Models for Doppler Measurements

    NASA Technical Reports Server (NTRS)

    Lear, William M.

    1987-01-01

    Error analysis increases precision of navigation. Report presents improved mathematical models of analysis of Doppler measurements and measurement errors of spacecraft navigation. To take advantage of potential navigational accuracy of Doppler measurements, precise equations relate measured cycle count to position and velocity. Drifts and random variations in transmitter and receiver oscillator frequencies taken into account. Mathematical models also adapted to aircraft navigation, radar, sonar, lidar, and interferometry.

  19. Compact Doppler magnetograph

    NASA Astrophysics Data System (ADS)

    Ruzmaikin, Alexander; Moynihan, Philip I.; Vaughan, Arthur H.; Cacciani, Alessandro

    1998-11-01

    We designed a low-cost flight instrument that images the full solar disk through two narrow band filters at the red nd blue 'wings' of the solar potassium absorption line. The images are produced on a 1024 X 1024 charge-coupled device with a resolution of 2 arcsec per pixel. Four filtergrams taken in a very short time at both wings in the left and right states of circular polarization are used to yield a Dopplergram and a magnetogram simultaneously. The noise-equivalent velocity associated with each pixel is less than 3 m/s. The measured signal is linearly proportional to the velocity in the range +/- 4000 m/s. The range of magnetic fields is from 3 to 3000 Gauss. The optical system of the instrument is simple and easily aligned. With a pixel size of 12 micrometers , the effective focal length is 126 cm. A Raleigh resolution limit of 4 arcsec is achieved with a 5-cm entrance apertures, providing an f/25 focal ratio. The foreoptic is a two-component telephoto lens serving to limit the overall optical length to 89 cm or less. The mass of the instrument is 14 kg. the power required is less than 30 Watts. The Compact Doppler Magnetograph can be used in space mission with severe mass and power requirements. It can also be effectively used for ground-based observations: large telescope, dome or other observatory facilities are not required.

  20. High Resolution Doppler Imager

    NASA Technical Reports Server (NTRS)

    Hays, Paul B.

    1999-01-01

    This report summarizes the accomplishments of the High Resolution Doppler Imager (HRDI) on UARS spacecraft during the period 4/l/96 - 3/31/99. During this period, HRDI operation, data processing, and data analysis continued, and there was a high level of vitality in the HRDI project. The HRDI has been collecting data from the stratosphere, mesosphere, and lower thermosphere since instrument activation on October 1, 1991. The HRDI team has stressed three areas since operations commenced: 1) operation of the instrument in a manner which maximizes the quality and versatility of the collected data; 2) algorithm development and validation to produce a high-quality data product; and 3) scientific studies, primarily of the dynamics of the middle atmosphere. There has been no significant degradation in the HRDI instrument since operations began nearly 8 years ago. HRDI operations are fairly routine, although we have continued to look for ways to improve the quality of the scientific product, either by improving existing modes, or by designing new ones. The HRDI instrument has been programmed to collect data for new scientific studies, such as measurements of fluorescence from plants, measuring cloud top heights, and lower atmosphere H2O.

  1. A Fisheye Lens as a Photonic Doppler Velocimetry Probe

    SciTech Connect

    Frogget, B. C.

    2012-08-16

    These presentation visuals report an instrument that, by use of a fish-eye lens, generates a beat signal using fiber mixing of unshifted light with Doppler-shifted light and measures the beat frequency. Ray trace diagrams are shown to illustrate advantages and disadvantages. The authors find their instrument has a long tracking distance, and large angle coverage. Index matching eases assembly, reduces return loss and flattens the field.

  2. Cas A Dynamics: Doppler and Proper Motion

    NASA Astrophysics Data System (ADS)

    DeLaney, Tracey; Smith, J.; Rudnick, L.; Ennis, J.; Rho, J.; Reach, W.; Kozasa, T.; Gomez, H.

    2006-06-01

    We present Doppler velocity images of the young supernova remnant Cassiopeia A in the infrared emission lines of Ar, Ne, Si, and S observed with the Spitzer IRS and covering nearly the whole extent of the remnant. The measured infrared velocities of the shocked ejecta range from -4000 km/s to +6000 km/s. The Si and S emission near the center of the remnant, that is associated with ejecta that have not yet encountered the reverse shock, also shows both red- and blue-shifted structures with velocities between -3000 km/s and +3000 km/s. These unshocked ejecta provide a unique opportunity to study the kinematics of the explosion free from the influences of the reverse shock and CSM. The infrared kinematics are compared to optical and X-ray Doppler velocities and optical, X-ray, and radio proper motions. This work was performed for the Jet Propulsion Laboratory, California Institute of Technology, sponsored by the United States Government under Prime Contract between California Institute of Technology and NASA.

  3. The coating design of phase-shifting reflector array with high reflectance and specified reflection phase shifts for static Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Xuanni; Zhang, Hui; Wang, Yijun

    2016-02-01

    The optical Doppler Michelson imaging interferometer is widely used for wind measurements. Four interferograms obtained simultaneously are needed to immune to environmental disturbances. Thus, a static and divided mirror Michelson interferometer is proposed. Its highlight is the phase-shifting reflector array, which divides one mirror into four quadrants coated by different multilayer films with high reflectance, specified phase steps π/2 and little polarization effects. By combining analytical and empirical method, four coatings are designed with software TFCalc. The simulated results showed good agreement with the desired optical properties. Due to the limitation of the optical material and function of the software TFCalc, there are some design errors within tolerance.

  4. Double-Edge Molecular Technique for Doppler Lidar Wind Measurement

    NASA Technical Reports Server (NTRS)

    Flesia, Cristina; Korb, C. Laurence

    1998-01-01

    The double-edge lidar technique for measuring the wind using molecular backscatter is described. Two high spectral resolution edge filters are located in the wings of the Rayleigh-Brillouin profile. This doubles the signal change per unit Doppler shift, the sensitivity, and gives nearly a factor of two improvement in measurement accuracy. The use of a crossover region is described where the sensitivity of a molecular and aerosol-based measurement are equal. This desensitizes the molecular measurement to the effects of aerosol scattering over a frequency range of +/- 100 m/s. We give methods for correcting for short-term frequency jitter and drift using a laser reference frequency measurement and methods for long-term frequency correction using a servo control system. The effects of Rayleigh-Brillouin scattering on the measurement are shown to be significant and are included in the analysis. Simulations for a conical scanning satellite-based lidar at 355 nm show an accuracy of 2-3 m/s for altitudes of 2 to 15 km for a 1 km vertical resolution, a satellite altitude of 400 km and a 200 km x 200 km spatial resolution. Results of ground based wind measurements are presented.

  5. Spacecraft Doppler tracking with a VLBI antenna

    NASA Technical Reports Server (NTRS)

    Comoretto, G.; Iess, L.; Bertotti, B.; Brenkle, J. P.; Horton, T.

    1990-01-01

    Preliminary results are reported from Doppler-shift measurements to the Voyager-2 spacecraft at a distance of 26 AU, obtained using the 32-m VLBI antenna at Medicina (Italy) during July and August 1988. The apparatus comprises the el-az antenna, an S-X-band receiver, a hydrogen maser to generate the reference signal, a Mark III VLBI terminal, and a digital tone extractor capable of isolating a tone of known frequency from a noisy signal and giving its phase and amplitude. A signal transmitted in S-band from the NASA Deep Space Network (DSN) station in Australia and retransmitted coherently in X-band by Voyager, was received 7 h 6 min later at Medicina and at the DSN station in Madrid. Sample data are presented graphically and shown to be of generally high quality; further in-depth analysis is under way.

  6. Power Doppler imaging: clinical experience and correlation with color Doppler US and other imaging modalities.

    PubMed

    Hamper, U M; DeJong, M R; Caskey, C I; Sheth, S

    1997-01-01

    Power Doppler imaging has recently gained attention as an additional color flow imaging technique that overcomes some of the limitations of conventional color Doppler ultrasound (US). Limitations of conventional color Doppler US include angle dependence, aliasing, and difficulty in separating background noise from true flow in slow-flow states. Owing to its increased sensitivity to flow, power Doppler sonography is valuable in low-flow states and when optimal Doppler angles cannot be obtained. Longer segments of vessels and more individual vessels can be visualized with power Doppler US than with conventional color Doppler sonography. Power Doppler sonography increases diagnostic confidence when verifying or excluding testicular or ovarian torsion and confirming thrombosis or occlusion of vessels. Power Doppler sonography also improves evaluation of parenchymal flow and decreases examination times in technically challenging cases. Power Doppler US is a useful adjunct to mean-frequency color Doppler sonography, especially when color Doppler US cannot adequately obtain or display diagnostic information. PMID:9084086

  7. Position-Specific Mass Shift Analysis: A Systematic Method for Investigating the EI-MS Fragmentation Mechanism of epi-Isozizaene.

    PubMed

    Rabe, Patrick; Klapschinski, Tim A; Dickschat, Jeroen S

    2016-07-15

    The EI-MS fragmentation mechanism of the bacterial sesquiterpene epi-isozizaene was investigated through enzymatic conversion of all 15 synthetic ((13) C1 )FPP isotopomers with the epi-isozizaene synthase from Streptomyces albus and GC-MS and GC-QTOF analysis including MS-MS. A systematic method, which we wish to call position-specific mass shift analysis, for the identification of the full set of fragmentation reactions was developed. PMID:27123899

  8. Coastal salinity measurement using a Doppler Radiometer

    NASA Astrophysics Data System (ADS)

    Schwarz, Benjamin S.; Tatnall, Adrian R. L.; Lewis, Hugh G.

    2012-10-01

    Coastal salinity is characterised by large and variable salinity contrasts on relatively small scales. Measurements of salinity at a resolution compatible with these coastal regions on a regular basis would provide a rich source of information that could be used for a number of applications that have a fundamental bearing on the world's lifestyle. Doppler radiometry offers an approach to capture such measurements, as it reduces the number of required antennas needed to form an image, compared with an Interferometer type instrument. In this work, a Doppler Radiometer type instrument on free-flying satellites is introduced. This approach removes the need for a physical connection between all the antennas, affords the system a degree of reconfigurability, yet is still able to provide data of sufficient resolution. A Y-shaped central hub (similar to the SMOS configuration) is employed with additional antennas mounted on free flying platforms surrounding the central hub. The additional baselines formed between the antennas of the free flying satellites and central hub as well as between the free flying satellites extend the u-v coverage beyond that of just the central hub. The spatial resolution of a Doppler Radiometer system with a Y-shaped hub with a SMOS configuration of antennas, with each arm extended by five 6 m spaced free flying antennas would be of the order of 5 km, when imaging from 800 km. This paper will present some initial results from a study into an instrument concept that could provide coastal salinity measurements at microwave wavelengths. The study focuses on antenna array design and on quantifying the improvement in spatial resolution available by using this method, and includes an investigation into the effects of the relative motion between the hub and the free flying satellites on the imaging. Further, whilst this paper focuses on the application of the Doppler Radiometer to salinity measurement, the techniques described are applicable to other

  9. The role of the Doppler in the differential diagnosis of lower extremity claudication syndromes.

    PubMed

    Terenzi, T J

    1990-05-01

    Certain doppler procedures can be used as screening methods, and may be helpful in detecting and locating arterial occlusive disease in the patient with vertebrogenic sciatica or claudication syndromes of the lower extremities. The doppler has become popular in the office setting because it is quick, noninvasive and inexpensive. The procedures can be performed even with the simple stethoscope doppler. A review of the basic types of equipment as well as pertinent data interpretation are covered in this article. The methods applied are multisegmental pressures and audible doppler flow signals. PMID:2191068

  10. Monitoring and Analysis of Respiratory Patterns Using Microwave Doppler Radar

    PubMed Central

    Pathirana, Pubudu N.; Steinfort, Christopher Louis; Caelli, Terry

    2014-01-01

    Noncontact detection characteristic of Doppler radar provides an unobtrusive means of respiration detection and monitoring. This avoids additional preparations, such as physical sensor attachment or special clothing, which can be useful for certain healthcare applications. Furthermore, robustness of Doppler radar against environmental factors, such as light, ambient temperature, interference from other signals occupying the same bandwidth, fading effects, reduce environmental constraints and strengthens the possibility of employing Doppler radar in long-term respiration detection, and monitoring applications such as sleep studies. This paper presents an evaluation in the of use of microwave Doppler radar for capturing different dynamics of breathing patterns in addition to the respiration rate. Although finding the respiration rate is essential, identifying abnormal breathing patterns in real-time could be used to gain further insights into respiratory disorders and refine diagnostic procedures. Several known breathing disorders were professionally role played and captured in a real-time laboratory environment using a noncontact Doppler radar to evaluate the feasibility of this noncontact form of measurement in capturing breathing patterns under different conditions associated with certain breathing disorders. In addition to that, inhalation and exhalation flow patterns under different breathing scenarios were investigated to further support the feasibility of Doppler radar to accurately estimate the tidal volume. The results obtained for both experiments were compared with the gold standard measurement schemes, such as respiration belt and spirometry readings, yielding significant correlations with the Doppler radar-based information. In summary, Doppler radar is highlighted as an alternative approach not only for determining respiration rates, but also for identifying breathing patterns and tidal volumes as a preferred nonwearable alternative to the conventional

  11. Ab initio calculations of external-field shifts of the 661-nm quadrupolar clock transition in neutral Ag atoms

    SciTech Connect

    Topcu, Suat; Nasser, Jamil; Daku, Latevi Max Lawson; Fritzsche, Stephan

    2006-04-15

    Frequency shifts of the Ag I 4d{sup 10}5s {sup 2}S{sub 1/2}(F=0,M{sub F}=0) to 4d{sup 9}5s{sup 2} {sup 2}D{sub 5/2}(F{sup '}=2,M{sub F{sup '}}=0) electric-quadrupole transition at 330.6 nm due to external fields are calculated using multiconfigurational self-consistent field methods. As this forbidden transition is free from first order Doppler and Zeeman effects, it is under investigation for the realization of an atomic optical clock. The calculated perturbations are the light shift, the blackbody frequency shift, and the quadratic Zeeman shift. Results show that a total uncertainty of 10{sup -18} could be reach without confining the atoms in a Lamb-Dicke regime in an optical lattice.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  13. Accuracy of three-dimensional multislice view Doppler in diagnosis of morbid adherent placenta

    PubMed Central

    Abdel Moniem, Alaa M.; Ibrahim, Ahmed; Akl, Sherif A.; Aboul-Enen, Loay; Abdelazim, Ibrahim A.

    2015-01-01

    Objective To detect the accuracy of the three-dimensional multislice view (3D MSV) Doppler in the diagnosis of morbid adherent placenta (MAP). Material and Methods Fifty pregnant women at ≥28 weeks gestation with suspected MAP were included in this prospective study. Two dimensional (2D) trans-abdominal gray-scale ultrasound scan was performed for the subjects to confirm the gestational age, placental location, and findings suggestive of MAP, followed by the 3D power Doppler and then the 3D MSV Doppler to confirm the diagnosis of MAP. Intraoperative findings and histopathology results of removed uteri in cases managed by emergency hysterectomy were compared with preoperative sonographic findings to detect the accuracy of the 3D MSV Doppler in the diagnosis of MAP. Results The 3D MSV Doppler increased the accuracy and predictive values of the diagnostic criteria of MAP compared with the 3D power Doppler. The sensitivity and negative predictive value (NPV) (79.6% and 82.2%, respectively) of crowded vessels over the peripheral sub-placental zone to detect difficult placental separation and considerable intraoperative blood loss in cases of MAP using the 3D power Doppler was increased to 82.6% and 84%, respectively, using the 3D MSV Doppler. In addition, the sensitivity, specificity, and positive predictive value (PPV) (90.9%, 68.8%, and 47%, respectively) of the disruption of the uterine serosa-bladder interface for the detection of emergency hysterectomy in cases of MAP using the 3D power Doppler was increased to 100%, 71.8%, and 50%, respectively, using the 3D MSV Doppler. Conclusion The 3D MSV Doppler is a useful adjunctive tool to the 3D power Doppler or color Doppler to refine the diagnosis of MAP. PMID:26401104

  14. Planetary Doppler Imaging

    NASA Astrophysics Data System (ADS)

    Murphy, N.; Jefferies, S.; Hart, M.; Hubbard, W. B.; Showman, A. P.; Hernandez, G.; Rudd, L.

    2014-12-01

    Determining the internal structure of the solar system's gas and ice giant planets is key to understanding their formation and evolution (Hubbard et al., 1999, 2002, Guillot 2005), and in turn the formation and evolution of the solar system. While internal structure can be constrained theoretically, measurements of internal density distributions are needed to uncover the details of the deep interior where significant ambiguities exist. To date the interiors of giant planets have been probed by measuring gravitational moments using spacecraft passing close to, or in orbit around the planet. Gravity measurements are effective in determining structure in the outer envelope of a planet, and also probing dynamics (e.g. the Cassini and Juno missions), but are less effective in probing deep structure or the presence of discrete boundaries. A promising technique for overcoming this limitation is planetary seismology (analogous to helioseismology in the solar case), postulated by Vorontsov, 1976. Using trapped pressure waves to probe giant planet interiors allows insight into the density and temperature distribution (via the sound speed) down to the planetary core, and is also sensitive to sharp boundaries, for example at the molecular to metallic hydrogen transition or at the core-envelope interface. Detecting such boundaries is not only important in understanding the overall structure of the planet, but also has implications for our understanding of the basic properties of matter at extreme pressures. Recent Doppler measurements of Jupiter by Gaulme et al (2011) claimed a promising detection of trapped oscillations, while Hedman and Nicholson (2013) have shown that trapped waves in Saturn cause detectable perturbations in Saturn's C ring. Both these papers have fueled interest in using seismology as a tool for studying the solar system's giant planets. To fully exploit planetary seismology as a tool for understanding giant planet structure, measurements need to be made

  15. Electrical system for pulse-width modulated control of a power inverter using phase-shifted carrier signals and related operating methods

    DOEpatents

    Welchko, Brian A.

    2012-02-14

    Systems and methods are provided for pulse-width modulated control of power inverter using phase-shifted carrier signals. An electrical system comprises an energy source and a motor. The motor has a first set of windings and a second set of windings, which are electrically isolated from each other. An inverter module is coupled between the energy source and the motor and comprises a first set of phase legs coupled to the first set of windings and a second set of phase legs coupled to the second set of windings. A controller is coupled to the inverter module and is configured to achieve a desired power flow between the energy source and the motor by modulating the first set of phase legs using a first carrier signal and modulating the second set of phase legs using a second carrier signal. The second carrier signal is phase-shifted relative to the first carrier signal.

  16. Acoustic resolution photoacoustic Doppler flowmetry: practical considerations for obtaining accurate measurements of blood flow

    NASA Astrophysics Data System (ADS)

    Brunker, J.; Beard, P.

    2014-03-01

    An assessment has been made of various experimental factors affecting the accuracy of flow velocities measured using a pulsed time correlation photoacoustic Doppler technique. In this method, Doppler time shifts are quantified via crosscorrelation of pairs of photoacoustic waveforms generated in moving absorbers using pairs of laser light pulses, and the photoacoustic waves are detected using an ultrasound transducer. The acoustic resolution mode is employed by using the transducer focal width, rather than the large illuminated volume, to define the lateral spatial resolution. This enables penetration depths of several millimetres or centimetres, unlike methods using the optical resolution mode, which limits the maximum penetration depth to approximately 1 mm. In the acoustic resolution mode, it is difficult to detect time shifts in highly concentrated suspensions of flowing absorbers, such as red blood cell suspensions and whole blood, and this challenge supposedly arises because of the lack of spatial heterogeneity. However, by assessing the effect of different absorption coefficients and tube diameters, we offer an alternative explanation relating to light attenuation and parabolic flow. We also demonstrate a new signal processing method that surmounts the previous problem of measurement under-reading. This method is a form of signal range gating and enables mapping of the flow velocity profile across the tube as well as measurement of the average flow velocity. We show that, using our signal processing scheme, it is possible to measure the flow of whole blood using a relatively low frequency detector. This important finding paves the way for application of the technique to measurements of blood flow several centimetres deep in living tissue.

  17. Doppler images of the RS CVn binary II Pegasi during the years 1994-2002

    NASA Astrophysics Data System (ADS)

    Lindborg, M.; Korpi, M. J.; Hackman, T.; Tuominen, I.; Ilyin, I.; Piskunov, N.

    2011-02-01

    Aims: We publish 16 Doppler imaging temperature maps for the years 1994-2002 of the active RS CVn star II Peg. The six maps from 1999-2002 are based on previously unpublished observations. Through Doppler imaging we want to study the spot evolution of the star and in particular compare this with previous results showing a cyclic spot behaviour and persistent, active longitudes. Methods: The observations were collected with the SOFIN spectrograph at the Nordic Optical Telescope. The temperature maps were calculated using a Doppler imaging code based on Tikhonov regularization. Results: During 1994-2001, our results show a consistent trend in the derived longitudes of the principal and secondary temperature minima over time such that the magnetic structure appears to rotate somewhat more rapidly than the orbital period of this close binary. A sudden phase jump in the active region occurred between the observing seasons of 2001 and 2002. No clear trend over time is detected in the derived latitudes of the spots, indicating that the systematic motion could be related to the drift of the spot-generating mechanism rather than to differential rotation. The derived temperature maps are quite similar to the ones obtained earlier with different methods and the main differences occur in the spot latitudes and relative strength of the spot structures. Conclusions: We observe both longitude and latitude shifts in the spot activity of II Peg. However, our results are not consistent with the periodic behaviour presented in previous studies. Full Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/526/A44

  18. Direct Detection Doppler Lidar for Spaceborne Wind Measurement

    NASA Technical Reports Server (NTRS)

    Korb, C. Laurence; Flesia, Cristina

    1999-01-01

    to noise ratio to be substantially improved in areas of low aerosol backscatter. We describe a method that allows the Rayleigh and aerosol components of the signal to be independently determined using the two edge channels and an energy monitor channel. The effects of Rayleigh scattering may then subtracted from the measurement and we show that the correction process does not significantly increase the measurement noise for Rayleigh to aerosol ratios up to 10. We show that for small Doppler shifts a measurement accuracy of 0.4 m/s can be obtained for 5000 detected photon, 1.2 m/s for 1000 detected photons, and 3.7 m/s for 50 detected photons for a Rayleigh to aerosol ratio of 5. Methods for increasing the dynamic range of the aerosol-based system to more than +/- 100 m/s are given.

  19. Direct Detection Doppler Lidar for Spaceborne Wind Measurement

    NASA Technical Reports Server (NTRS)

    Korb, C. Laurence; Flesia, Cristina

    1999-01-01

    The theory of double edge lidar techniques for measuring the atmospheric wind using aerosol and molecular backscatter is described. Two high spectral resolution filters with opposite slopes are located about the laser frequency for the aerosol based measurement or in the wings of the Rayleigh - Brillouin profile for the molecular measurement. This doubles the signal change per unit Doppler shift and improves the measurement accuracy by nearly a factor of 2 relative to the single edge technique. For the aerosol based measurement, the use of two high resolution edge filters reduces the effects of background, Rayleigh scattering, by as much as an order of magnitude and substantially improves the measurement accuracy. Also, we describe a method that allows the Rayleigh and aerosol components of the signal to be independently determined. A measurement accuracy of 1.2 m/s can be obtained for a signal level of 1000 detected photons which corresponds to signal levels in the boundary layer. For the molecular based measurement, we describe the use of a crossover region where the sensitivity of a molecular and aerosol-based measurement are equal. This desensitizes the molecular measurement to the effects of aerosol scattering and greatly simplifies the measurement. Simulations using a conical scanning spaceborne lidar at 355 nm give an accuracy of 2-3 m/s for altitudes of 2-15 km for a 1 km vertical resolution, a satellite altitude of 400 km, and a 200 km x 200 km spatial.

  20. Windowed multipole for cross section Doppler broadening

    NASA Astrophysics Data System (ADS)

    Josey, C.; Ducru, P.; Forget, B.; Smith, K.

    2016-02-01

    This paper presents an in-depth analysis on the accuracy and performance of the windowed multipole Doppler broadening method. The basic theory behind cross section data is described, along with the basic multipole formalism followed by the approximations leading to windowed multipole method and the algorithm used to efficiently evaluate Doppler broadened cross sections. The method is tested by simulating the BEAVRS benchmark with a windowed multipole library composed of 70 nuclides. Accuracy of the method is demonstrated on a single assembly case where total neutron production rates and 238U capture rates compare within 0.1% to ACE format files at the same temperature. With regards to performance, clock cycle counts and cache misses were measured for single temperature ACE table lookup and for windowed multipole. The windowed multipole method was found to require 39.6% more clock cycles to evaluate, translating to a 7.9% performance loss overall. However, the algorithm has significantly better last-level cache performance, with 3 fewer misses per evaluation, or a 65% reduction in last-level misses. This is due to the small memory footprint of the windowed multipole method and better memory access pattern of the algorithm.