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Sample records for adaptive spectral doppler

  1. Adaptive Spectral Doppler Estimation

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-01-01

    In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence....... The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested and...... compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of...

  2. Spectral Doppler estimation utilizing 2-D spatial information and adaptive signal processing.

    Ekroll, Ingvild K; Torp, Hans; Løvstakken, Lasse

    2012-06-01

    The trade-off between temporal and spectral resolution in conventional pulsed wave (PW) Doppler may limit duplex/triplex quality and the depiction of rapid flow events. It is therefore desirable to reduce the required observation window (OW) of the Doppler signal while preserving the frequency resolution. This work investigates how the required observation time can be reduced by adaptive spectral estimation utilizing 2-D spatial information obtained by parallel receive beamforming. Four adaptive estimation techniques were investigated, the power spectral Capon (PSC) method, the amplitude and phase estimation (APES) technique, multiple signal classification (MUSIC), and a projection-based version of the Capon technique. By averaging radially and laterally, the required covariance matrix could successfully be estimated without temporal averaging. Useful PW spectra of high resolution and contrast could be generated from ensembles corresponding to those used in color flow imaging (CFI; OW = 10). For a given OW, the frequency resolution could be increased compared with the Welch approach, in cases in which the transit time was higher or comparable to the observation time. In such cases, using short or long pulses with unfocused or focused transmit, an increase in temporal resolution of up to 4 to 6 times could be obtained in in vivo examples. It was further shown that by using adaptive signal processing, velocity spectra may be generated without high-pass filtering the Doppler signal. With the proposed approach, spectra retrospectively calculated from CFI may become useful for unfocused as well as focused imaging. This application may provide new clinical information by inspection of velocity spectra simultaneously from several spatial locations. PMID:22711413

  3. Maximum-likelihood spectral estimation and adaptive filtering techniques with application to airborne Doppler weather radar. Thesis Technical Report No. 20

    Lai, Jonathan Y.

    1994-01-01

    This dissertation focuses on the signal processing problems associated with the detection of hazardous windshears using airborne Doppler radar when weak weather returns are in the presence of strong clutter returns. In light of the frequent inadequacy of spectral-processing oriented clutter suppression methods, we model a clutter signal as multiple sinusoids plus Gaussian noise, and propose adaptive filtering approaches that better capture the temporal characteristics of the signal process. This idea leads to two research topics in signal processing: (1) signal modeling and parameter estimation, and (2) adaptive filtering in this particular signal environment. A high-resolution, low SNR threshold maximum likelihood (ML) frequency estimation and signal modeling algorithm is devised and proves capable of delineating both the spectral and temporal nature of the clutter return. Furthermore, the Least Mean Square (LMS) -based adaptive filter's performance for the proposed signal model is investigated, and promising simulation results have testified to its potential for clutter rejection leading to more accurate estimation of windspeed thus obtaining a better assessment of the windshear hazard.

  4. An Efficient Adaptive Angle-Doppler Compensation Approach for Non-Sidelooking Airborne Radar STAP

    Mingwei Shen

    2015-06-01

    Full Text Available In this study, the effects of non-sidelooking airborne radar clutter dispersion on space-time adaptive processing (STAP is considered, and an efficient adaptive angle-Doppler compensation (EAADC approach is proposed to improve the clutter suppression performance. In order to reduce the computational complexity, the reduced-dimension sparse reconstruction (RDSR technique is introduced into the angle-Doppler spectrum estimation to extract the required parameters for compensating the clutter spectral center misalignment. Simulation results to demonstrate the effectiveness of the proposed algorithm are presented.

  5. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations. The process, described by a three-level model with the Λ scheme, shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms. The |Fg = 3> → |Fe = 4> resonance pumping can result in the ground state |Fg = 4, mF = 4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg = 4. To enhance the anisotropy in the ground state, we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg = 4> → |Fe = 3> transition, in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field. (atomic and molecular physics)

  6. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    Zhang Jun-Hai; Zeng Xian-Jin; Li Qing-Meng; Huang Qiang; Sun Wei-Min

    2013-01-01

    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations.The process,described by a three-level model with the A scheme,shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms.The |Fg =3> → |Fe-4> resonance pumping can result in the ground state |Fg =4,mF =4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg =4.To enhance the anisotropy in the ground state,we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg =4> → |Fe =3>transition,in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field.

  7. Velocity Variation Assessment of Red Blood Cell Aggregation with Spectral Domain Doppler Optical Coherence Tomography

    Xu, Xiangqun; Yu, Lingfeng; Chen, Zhongping

    2010-01-01

    We propose spectral domain Doppler optical coherence tomography (SD-D-OCT) to qualitatively measure red blood cell aggregation. Variance/standard deviation (SD) of the Doppler frequency spectrum in Doppler variance imaging of flowing blood under shearing conditions was developed as a new aggregation index. In in vitro microchannel-flow experiments, porcine blood at various hematocrits with aggregation characteristics induced by dextran 500 or at the presence of plasma fibrinogen was measured ...

  8. Correlation between Spectral Index and Doppler Factor for a Sample of Fermi Blazars

    J. Tao; J. H. Fan; H. J. Pan; D. X. Wu; S. H. Li

    2014-09-01

    Relativistic beaming effect is important for blazars. In a very recent work, -ray Doppler factors were calculated for a sample of Fermi blazars (Fan et al. 2013). In this work, we investigated the correlation between the Doppler factor and the effective spectral index, 4OX, and found an anticorrelation between them.

  9. Spectral fine structure effects on material and doppler reactivity worth

    New formulations concerning the fine structure effects on the reactivity worth of resonances are developed and conclusions are derived following the extension to more general types of perturbations which include: the removal of resonance material at finite temperatures and the temperature variation of part of the resonance material. It is concluded that the flux method can overpredict the reactivity worth of resonance materials more than anticipated. Calculations on the Doppler worth were carried out; the results can be useful for asessing the contribution of the fine structure effects to the large discrepancy that exists between the calculated and measured small sample Doppler worths. (B.G.)

  10. Performance Bounds on Micro-Doppler Estimation and Adaptive Waveform Design Using OFDM Signals

    Sen, Satyabrata [ORNL; Barhen, Jacob [ORNL; Glover, Charles Wayne [ORNL

    2014-01-01

    We analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a target having multiple rotating scatterers (e.g., rotor blades of a helicopter, propellers of a submarine). The presence of rotating scatterers introduces Doppler frequency modulation in the received signal by generating sidebands about the transmitted frequencies. This is called the micro-Doppler effects. The use of a frequency-diverse OFDM signal in this context enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. Therefore, to characterize the accuracy of micro-Doppler frequency estimation, we compute the Cram er-Rao Bound (CRB) on the angular-velocity estimate of the target while considering the scatterer responses as deterministic but unknown nuisance parameters. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the transmitting OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations at different values of the signal-to-noise ratio (SNR) and the number of OFDM subcarriers. The CRB values not only decrease with the increase in the SNR values, but also reduce as we increase the number of subcarriers implying the significance of frequency-diverse OFDM waveforms. The improvement in estimation accuracy due to the adaptive waveform design is also numerically analyzed. Interestingly, we find that the relative decrease in the CRBs on the angular-velocity estimate is more pronounced for larger number of OFDM subcarriers.

  11. Performance bounds on micro-Doppler estimation and adaptive waveform design using OFDM signals

    Sen, Satyabrata; Barhen, Jacob; Glover, Charles W.

    2014-05-01

    We analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a target having multiple rotating scatterers (e.g., rotor blades of a helicopter, propellers of a submarine). The presence of rotating scatterers introduces Doppler frequency modulation in the received signal by generating sidebands about the transmitted frequencies. This is called the micro-Doppler effects. The use of a frequency-diverse OFDM signal in this context enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. Therefore, to characterize the accuracy of micro-Doppler frequency estimation, we compute the Craḿer-Rao Bound (CRB) on the angular-velocity estimate of the target while considering the scatterer responses as deterministic but unknown nuisance parameters. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the transmitting OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations at different values of the signal-to-noise ratio (SNR) and the number of OFDM subcarriers. The CRB values not only decrease with the increase in the SNR values, but also reduce as we increase the number of subcarriers implying the significance of frequency-diverse OFDM waveforms. The improvement in estimation accuracy due to the adaptive waveform design is also numerically analyzed. Interestingly, we find that the relative decrease in the CRBs on the angular-velocity estimate is more pronounced for larger number of OFDM subcarriers.

  12. Dispersion corrections to the Gaussian profile describing the Doppler broadening of spectral lines

    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.

  13. Ultra-Fast Displaying Spectral Domain Optical Doppler Tomography System Using a Graphics Processing Unit

    Jeong-Yeon Kim; Changho Lee; Hyosang Jeong; Unsang Jung; Nam Hyun Cho; Jeehyun Kim

    2012-01-01

    We demonstrate an ultrafast displaying Spectral Domain Optical Doppler Tomography system using Graphics Processing Unit (GPU) computing. The calculation of FFT and the Doppler frequency shift is accelerated by the GPU. Our system can display processed OCT and ODT images simultaneously in real time at 120 fps for 1,024 pixels × 512 lateral A-scans. The computing time for the Doppler information was dependent on the size of the moving average window, but with a window size of 32 pixels the ODT ...

  14. The Doppler Effect and Spectral Energy Distribution of Blazars

    2001-01-01

    The relativistic beaming model is adopted to discuss quantitatively the observational differences between radio-selected BL Lac objects (RBLs) and X-ray-selected BL Lac objects (XBLs), and between BL Lac objects and fiat spectrum radio quasars (FSRQs). The main results are the following: (1) In the Doppler cor-rected color-color (αin ro-αin ox -αox) diagram, XBLs and FSRQs occupy separated regions,while RBLs bridge the gap between them. These properties suggest that similar in- trinsic physical processes operate in all the objects under a range of intrinsic physical conditions. (2) Our results are consistent with the results of Sambruna, Maraschi and Urry (1996) from other methods. We show the αxox introduced by Sambruna to be a good index for describing the energy distribution because it represents the intrinsic energy distribution and includes the Doppler correction. (3) The Doppler effect of relativistic beaming is the main mechanism, and the physical differences (such as magnetic fields, electron energies) are also important complementary fac-tors for understanding the relation between XBLs and RBLs;

  15. Demonstration of a spatial-spectral holographic LIDAR range-Doppler processor

    We present a new approach to laser interferometric Doppler and ranging (LIDAR) processing using spatial-spectral holography (SSH). In this approach, broadband optical signals from a random noise or frequency-modulated laser are transmitted and reflected off remote targets. The return signals interfere spatially and spectrally with a local copy of the original transmit signal in an SSH medium, resulting in spectral gratings that have a spectral period inversely proportional to the LIDAR target's range and a position proportional to the target's Doppler (or velocity). These gratings are subsequently read out by a slowly chirped source onto a parallel detector array, and the velocity and range of the targets are inferred. We present the theoretical framework that describes the function of the LIDAR processor, as well as proof-of-concept experimental results

  16. Adaptable Multivariate Calibration Models for Spectral Applications

    THOMAS,EDWARD V.

    1999-12-20

    Multivariate calibration techniques have been used in a wide variety of spectroscopic situations. In many of these situations spectral variation can be partitioned into meaningful classes. For example, suppose that multiple spectra are obtained from each of a number of different objects wherein the level of the analyte of interest varies within each object over time. In such situations the total spectral variation observed across all measurements has two distinct general sources of variation: intra-object and inter-object. One might want to develop a global multivariate calibration model that predicts the analyte of interest accurately both within and across objects, including new objects not involved in developing the calibration model. However, this goal might be hard to realize if the inter-object spectral variation is complex and difficult to model. If the intra-object spectral variation is consistent across objects, an effective alternative approach might be to develop a generic intra-object model that can be adapted to each object separately. This paper contains recommendations for experimental protocols and data analysis in such situations. The approach is illustrated with an example involving the noninvasive measurement of glucose using near-infrared reflectance spectroscopy. Extensions to calibration maintenance and calibration transfer are discussed.

  17. Role of spectral doppler in the differentiation of benign and malignant cervical lymphadenopathy

    Mohmed Imran Wagay

    2014-10-01

    Full Text Available Introduction: Differentiating benign from malignant lymphadenopathy is often a diagnostic challenge to medical professionals and multiple non invasive modalities from palpation to MRI have been used. Histopathology remains the gold standard but imaging modalities are frequently used. The main objective of our study is to assess the accuracy of spectral Doppler in differentiating benign and malignant lymphadenopathy. Methods: A prospective study was done in patients with cervical nodes and the Doppler study was done primarily assessing the spectral doppler features and the diagnosis was compared with histopathology. Results: Reactive nodes usually showed hilar vascularity. Metastatic nodes showed Peripheral and chaotic multifocal vascular signals. Resistive Index and Pulsatility Index were the most important markers among the spectral parameters for the differentiation of benign and malignant lymphadenopathy. RI and PI of malignant nodes was significantly higher than benign nodes. PSV of the nodes was not much different but EDV was low in metastatic nodes. EDV> 11.1 cm/s has 100% negative predictive value for nodal metastasis, and EDV<3.4 cm/s has 100% specificity and PPV for metastasis. Tubercular nodes shows indeterminate doppler characteristics. Conclusion: Colour doppler sonography is a highly efficacious investigation for differentiation of benign and malignant lymphadenopathy Colour doppler can be used to prevent unnecessary invasive biopsy in many patients particularly in those patients where we get very low values of RI and PI and very high values for EDV. RI is the single most important parameter in the differentiation of benign and malignant lymphadenopathy. Cut off value of 0.7 for RI and 1.3 for PI, yield acceptable sensitivity, specificity and accuracy.

  18. Ultraviolet high-spectral-resolution Doppler lidar for measuring wind field and aerosol optical properties

    An ultraviolet incoherent Doppler lidar that incorporates the high-spectral-resolution (HSR) technique has been developed for measuring the wind field and aerosol optical properties in the troposphere. An injection seeded and tripled Nd:YAG laser at an ultraviolet wavelength of 355 nm was used in the lidar system. The HRS technique can resolve the aerosol Mie backscatter and the molecular Rayleigh backscatter to derive the signal components. By detecting the Mie backscatter, a great increase in the Doppler filter sensitivity was realized compared to the conventional incoherent Doppler lidars that detected the Rayleigh backscatter. The wind velocity distribution in a two-dimensional cross section was measured. By using the HSR technique, multifunction and absolute value measurements were realized for aerosol extinction, and volume backscatter coefficients; the laser beam transmittance, the lidar ratio, and the backscatter ratio are derived from these measurements

  19. ASSESSMENT OF VERTEBRAL ARTERIES BLOOD FLOW SPECTRAL DOPPLER INDICES IN COMPARISON WITH INTERNAL AND COMMON CAROTID ARTERIES BLOOD FLOW SPECTRAL DOPPLER INDICES

    H. Mazaher

    2007-05-01

    Full Text Available Vertebrobasilar insufficiency is the cause of cerebrovascular accidents in 20% of cases. There are few reports regarding spectral Doppler indices (SDIs of vertebral arteries (VAs normal blood flow. The objective of this study was to provide basic reference data about SDIs of VAs normal blood flow separately and in comparison with internal carotid arteries (ICAs and common carotid arteries (CCAs normal blood flows SDIs. This cross-sectional study performed on 70 normal patients. Color Doppler sonography (CDS and spectral Doppler sonography (SDS of right and left VAs (RVA and LVA, right and left CCAs (RCCA and LCCA, right and left ICAs (RICA and LICA, were performed. The mean PSV, EDV, and RI values of RVA blood flow were as 41.60 ± 9.6 cm/s, 14.60 ± 3.7 cm/s and 0.65 ± 0.06, and the mean PSV, EDV and RI values of LVA blood flow were as 42.20 ± 10.2 cm/s, 15.20 ± 4.2 cm/s, and 0.64 ± 0.05, respectively. There was not statistically significant difference between the mean PSV, EDV and RI values of RVA and LVA blood flows. The mean PSV and EDV values of VAs blood flows were significantly lower than the values of CCAs and ICCAs blood flows, respectively. The mean RI value of VAs blood flows was significantly lower than the mean RI Value of CCAs blood flows, but there was not statistically significant difference between the mean RI value of VAs blood flows and the mean RI value of ICAs blood flows.

  20. Simultaneous Spectral Temporal Adaptive Raman Spectrometer - SSTARS

    Blacksberg, Jordana

    2010-01-01

    Raman spectroscopy is a prime candidate for the next generation of planetary instruments, as it addresses the primary goal of mineralogical analysis, which is structure and composition. However, large fluorescence return from many mineral samples under visible light excitation can render Raman spectra unattainable. Using the described approach, Raman and fluorescence, which occur on different time scales, can be simultaneously obtained from mineral samples using a compact instrument in a planetary environment. This new approach is taken based on the use of time-resolved spectroscopy for removing the fluorescence background from Raman spectra in the laboratory. In the SSTARS instrument, a visible excitation source (a green, pulsed laser) is used to generate Raman and fluorescence signals in a mineral sample. A spectral notch filter eliminates the directly reflected beam. A grating then disperses the signal spectrally, and a streak camera provides temporal resolution. The output of the streak camera is imaged on the CCD (charge-coupled device), and the data are read out electronically. By adjusting the sweep speed of the streak camera, anywhere from picoseconds to milliseconds, it is possible to resolve Raman spectra from numerous fluorescence spectra in the same sample. The key features of SSTARS include a compact streak tube capable of picosecond time resolution for collection of simultaneous spectral and temporal information, adaptive streak tube electronics that can rapidly change from one sweep rate to another over ranges of picoseconds to milliseconds, enabling collection of both Raman and fluorescence signatures versus time and wavelength, and Synchroscan integration that allows for a compact, low-power laser without compromising ultimate sensitivity.

  1. Perceptual Adaptation of Voice Gender Discrimination with Spectrally Shifted Vowels

    Li, Tianhao; Fu, Qian-Jie

    2011-01-01

    Purpose: To determine whether perceptual adaptation improves voice gender discrimination of spectrally shifted vowels and, if so, which acoustic cues contribute to the improvement. Method: Voice gender discrimination was measured for 10 normal-hearing subjects, during 5 days of adaptation to spectrally shifted vowels, produced by processing the…

  2. Ultra-Fast Displaying Spectral Domain Optical Doppler Tomography System Using a Graphics Processing Unit

    Jeong-Yeon Kim

    2012-05-01

    Full Text Available We demonstrate an ultrafast displaying Spectral Domain Optical Doppler Tomography system using Graphics Processing Unit (GPU computing. The calculation of FFT and the Doppler frequency shift is accelerated by the GPU. Our system can display processed OCT and ODT images simultaneously in real time at 120 fps for 1,024 pixels × 512 lateral A-scans. The computing time for the Doppler information was dependent on the size of the moving average window, but with a window size of 32 pixels the ODT computation time is only 8.3 ms, which is comparable to the data acquisition time. Also the phase noise decreases significantly with the window size. Since the performance of a real-time display for OCT/ODT is very important for clinical applications that need immediate diagnosis for screening or biopsy. Intraoperative surgery can take much benefit from the real-time display flow rate information from the technology. Moreover, the GPU is an attractive tool for clinical and commercial systems for functional OCT features as well.

  3. Statistical characteristics of Doppler spectral width as observed by the conjugate SuperDARN radars

    K. Hosokawa

    Full Text Available We performed a statistical analysis of the occurrence distribution of Doppler spectral width around the day-side high-latitude ionosphere using data from the conjugate radar pair composed of the CUTLASS Iceland-East radar in the Northern Hemisphere and the SENSU Syowa-East radar in the Southern Hemisphere. Three types of spectral width distribution were identified: (1 an exponential-like distribution in the lower magnetic latitudes (below 72°, (2 a Gaussian-like distribution around a few degrees magnetic latitude, centered on 78°, and (3 another type of distribution in the higher magnetic latitudes (above 80°. The first two are considered to represent the geophysical regimes such as the LLBL and the cusp, respectively, because they are similar to the spectral width distributions within the LLBL and the cusp, as classified by Baker et al. (1995. The distribution found above 80° magnetic latitude has been clarified for the first time in this study. This distribution has similarities to the exponential-like distribution in the lower latitude part, although clear differences also exist in their characteristics. These three spectral width distributions are commonly identified in conjugate hemispheres. The latitudinal transition from one distribution to another exhibits basically the same trend between two hemispheres. There is, however, an interhemispheric difference in the form of the distribution around the cusp latitudes, such that spectral width values obtained from Syowa-East are larger than those from Iceland-East. On the basis of the spectral width characteristics, the average locations of the cusp and the open/closed field line boundary are estimated statistically.

    Key words. Ionosphere (ionosphere-magnetosphere inter-actions; plasma convection – Magnetospheric physics (magnetopause, cusp, and boundary layers

  4. Doppler radar spectral width broadening due to beamwidth and wind shear

    G. D. Nastrom

    Full Text Available The spectral width observed by Doppler radars can be due to several effects including the atmospheric turbulence within the radar sample volume plus effects associated with the background flow and the radar geometry and configuration. This study re-examines simple models for the effects due to finite beamwidth and vertical shear of the horizontal wind. Analytic solutions of 1- and 2-dimensional models are presented. Comparisons of the simple 2-dimensional model with numerical integrations of a 3-dimensional model with a symmetrical Gaussian beam show that the 2-dimensional model is usually adequate. The solution of the 2-dimensional model gives a formula that can be applied easily to large data sets. Analysis of the analytic solutions of the 2-dimensional model for off-vertical beams reveals a term that has not been included in mathematical formulas for spectral broadening in the past. This term arises from the simultaneous effects of the changing geometry due to curvature within a finite beamwidth and the vertical wind shear. The magnitude of this effect can be comparable to that of the well-known effects of beam-broadening and wind shear, and since it can have either algebraic sign, it can significantly reduce (or increase the expected spectral broadening, although under typical conditions it is smaller than the beam-broadening effect. The predictions of this simple model are found to be consistent with observations from the VHF radar at White Sands Missile Range, NM.

  5. Adaptive mesh strategies for the spectral element method

    Mavriplis, Catherine

    1992-01-01

    An adaptive spectral method was developed for the efficient solution of time dependent partial differential equations. Adaptive mesh strategies that include resolution refinement and coarsening by three different methods are illustrated on solutions to the 1-D viscous Burger equation and the 2-D Navier-Stokes equations for driven flow in a cavity. Sharp gradients, singularities, and regions of poor resolution are resolved optimally as they develop in time using error estimators which indicate the choice of refinement to be used. The adaptive formulation presents significant increases in efficiency, flexibility, and general capabilities for high order spectral methods.

  6. Power spectral density of velocity fluctuations estimated from phase Doppler data

    Jicha Miroslav

    2012-04-01

    Full Text Available Laser Doppler Anemometry (LDA and its modifications such as PhaseDoppler Particle Anemometry (P/DPA is point-wise method for optical nonintrusive measurement of particle velocity with high data rate. Conversion of the LDA velocity data from temporal to frequency domain – calculation of power spectral density (PSD of velocity fluctuations, is a non trivial task due to nonequidistant data sampling in time. We briefly discuss possibilities for the PSD estimation and specify limitations caused by seeding density and other factors of the flow and LDA setup. Arbitrary results of LDA measurements are compared with corresponding Hot Wire Anemometry (HWA data in the frequency domain. Slot correlation (SC method implemented in software program Kern by Nobach (2006 is used for the PSD estimation. Influence of several input parameters on resulting PSDs is described. Optimum setup of the software for our data of particle-laden air flow in realistic human airway model is documented. Typical character of the flow is described using PSD plots of velocity fluctuations with comments on specific properties of the flow. Some recommendations for improvements of future experiments to acquire better PSD results are given.

  7. In-vivo studies of new vector velocity and adaptive spectral estimators in medical ultrasound

    Hansen, Kristoffer Lindskov

    In this PhD project new ultrasound techniques for blood flow measurements have been investigated in-vivo. The focus has mainly been on vector velocity techniques and four different approaches have been examined: Transverse Oscillation, Synthetic Transmit Aperture, Directional Beamforming and Plane...... Wave Excitation. Furthermore two different adaptive spectral estimators have been investigated: Blood spectral Power Capon method (BPC) and Blood Amplitude and Phase Estimation method (BAPES). The novel techniques investigated in this thesis are developed to circumvent some of the main limitations in...... conventional Doppler ultrasound. That is angle dependency, reduced temporal resolution and low frame rate. Transverse Oscillation, Synthetic Transmit Aperture and Directional Beamforming can estimate the blood velocity angle independently. The three methods were validated in-vivo against magnetic resonance...

  8. A software sampling frequency adaptive algorithm for reducing spectral leakage

    PAN Li-dong; WANG Fei

    2006-01-01

    Spectral leakage caused by synchronous error in a nonsynchronous sampling system is an important cause that reduces the accuracy of spectral analysis and harmonic measurement.This paper presents a software sampling frequency adaptive algorithm that can obtain the actual signal frequency more accurately,and then adjusts sampling interval base on the frequency calculated by software algorithm and modifies sampling frequency adaptively.It can reduce synchronous error and impact of spectral leakage;thereby improving the accuracy of spectral analysis and harmonic measurement for power system signal where frequency changes slowly.This algorithm has high precision just like the simulations show,and it can be a practical method in power system harmonic analysis since it can be implemented easily.

  9. Infrared adaptive spectral imagers for direct detection of spectral signatures and hyperspectral imagery

    Goldstein, Neil; Fox, Marsha; Adler-Golden, Steven; Gregor, Brian

    2013-03-01

    Field test results are presented for a prototype long-wave adaptive imager that provides both hyperspectral imagery and contrast imagery based on the direct application of hyperspectral detection algorithms in hardware. Programmable spatial light modulators are used to provide both spectral and spatial resolution using a single element detector. Programmable spectral and spatial detection filters can be used to superimpose any possible analog spectral detection filter on the image. In this work, we demonstrate three modes of operation, including hyperspectral imagery, and one and two-dimensional imagery using a generalized matched filter for detection of a specific target gas within the scene.

  10. Combined vector velocity and spectral Doppler imaging for improved imaging of complex blood flow in the carotid arteries.

    Ekroll, Ingvild Kinn; Dahl, Torbjørn; Torp, Hans; Løvstakken, Lasse

    2014-07-01

    Color flow imaging and pulsed wave (PW) Doppler are important diagnostic tools in the examination of patients with carotid artery disease. However, measurement of the true peak systolic velocity is dependent on sample volume placement and the operator's ability to provide an educated guess of the flow direction. Using plane wave transmissions and a duplex imaging scheme, we present an all-in-one modality that provides both vector velocity and spectral Doppler imaging from one acquisition, in addition to separate B-mode images of sufficient quality. The vector Doppler information was used to provide automatically calibrated (angle-corrected) PW Doppler spectra at every image point. It was demonstrated that the combined information can be used to generate spatial maps of the peak systolic velocity, highlighting regions of high velocity and the extent of the stenotic region, which could be used to automate work flow as well as improve the accuracy of measurement of true peak systolic velocity. The modality was tested in a small group (N = 12) of patients with carotid artery disease. PW Doppler, vector velocity and B-mode images could successfully be obtained from a single recording for all patients with a body mass index ranging from 21 to 31 and a carotid depth ranging from 16 to 28 mm. PMID:24785436

  11. An example of scaling MST Doppler spectra using median spectra, spectral smoothing, and velocity tracing

    Green, J. L.

    1986-01-01

    Although automatic, computer scaling methods appeared at the start of the MST (mesosphere stratosphere troposphere) radar technique, there is a continuing need for scaling algorithms that perform editing functions and increase the sensitivity of radar by post processing. The scaling method presented is an adaptation of the method of scaling MST Doppler spectra presented by Rastogi (1984). A brief overview of this method is as follows: a median spectrum is calculated from several sequential spectra; the median noise value is subtracted from this derived spectrum; the median spectrum is smoothed; the detection/nondetection decision is made by comparing the smoothed spectrum to the variance of the smoothed noise; and if a signal is detected, then the half-power points of the smoothed echo spectrum are used to place limits on the evaluation of the first two moments of the unsmoothed median spectrum. In all of the above steps, the algorithm is guided by tracing the expected velocity range upward from the lowest range as far as possible. The method is discussed in more detail.

  12. Adaptive spectral identification techniques in presence of undetected non linearities

    Cella, G; Guidi, G M

    2002-01-01

    The standard procedure for detection of gravitational wave coalescing binaries signals is based on Wiener filtering with an appropriate bank of template filters. This is the optimal procedure in the hypothesis of addictive Gaussian and stationary noise. We study the possibility of improving the detection efficiency with a class of adaptive spectral identification techniques, analyzing their effect in presence of non stationarities and undetected non linearities in the noise

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

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

    2013-12-01

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

  14. Wavelet and model-based spectral analysis of color doppler optical coherence tomography

    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.

  15. Operator Auditory Perception and Spectral Quantification of Umbilical Artery Doppler Ultrasound Signals

    Thuring, Ann; Brännström, Jonas; Ewerlöf, Maria; Hernandez-Andrade, Edgar; Ley, David; Lingman, Göran; Liuba, Karina; Marsal, Karel; Jansson, Tomas

    2013-01-01

    Objective An experienced sonographer can by listening to the Doppler audio signals perceive various timbres that distinguish different types of umbilical artery flow despite an unchanged pulsatility index (PI). Our aim was to develop an objective measure of the Doppler audio signals recorded from fetoplacental circulation in a sheep model. Methods Various degrees of pathological flow velocity waveforms in the umbilical artery, similar to those in human complicated pregnancies, were induced by...

  16. Wideband range-Doppler processing and beamforming using electro-optic arrays and spectral hole burning materials.

    Braker, Benjamin; Wagner, Kelvin

    2010-07-01

    Ubiquitous radar systems look everywhere at all times and require both parallel radar processors and parallel beamformers. Current systems operate with subgigahertz bandwidths and produce a handful of angle-of-arrival (AOA) beams. We present an electro-optic radar processor that combines the multigigahertz wideband capabilities of a spectral hole burning correlator with wideband Doppler processing and the thousands of parallel channels available from an electro-optical beamformer. Preliminary experiments demonstrate 150 MHz bandwidth range correlations across 20 AOA beams. PMID:20648114

  17. A Spectral Adaptive Mesh Refinement Method for the Burgers equation

    Nasr Azadani, Leila; Staples, Anne

    2013-03-01

    Adaptive mesh refinement (AMR) is a powerful technique in computational fluid dynamics (CFD). Many CFD problems have a wide range of scales which vary with time and space. In order to resolve all the scales numerically, high grid resolutions are required. The smaller the scales the higher the resolutions should be. However, small scales are usually formed in a small portion of the domain or in a special period of time. AMR is an efficient method to solve these types of problems, allowing high grid resolutions where and when they are needed and minimizing memory and CPU time. Here we formulate a spectral version of AMR in order to accelerate simulations of a 1D model for isotropic homogenous turbulence, the Burgers equation, as a first test of this method. Using pseudo spectral methods, we applied AMR in Fourier space. The spectral AMR (SAMR) method we present here is applied to the Burgers equation and the results are compared with the results obtained using standard solution methods performed using a fine mesh.

  18. Operator Auditory Perception and Spectral Quantification of Umbilical Artery Doppler Ultrasound Signals

    Thuring, Ann; Brännström, K. Jonas; Ewerlöf, Maria; Hernandez-Andrade, Edgar; Ley, David; Lingman, Göran; Liuba, Karina; Maršál, Karel; Jansson, Tomas

    2013-01-01

    Objective An experienced sonographer can by listening to the Doppler audio signals perceive various timbres that distinguish different types of umbilical artery flow despite an unchanged pulsatility index (PI). Our aim was to develop an objective measure of the Doppler audio signals recorded from fetoplacental circulation in a sheep model. Methods Various degrees of pathological flow velocity waveforms in the umbilical artery, similar to those in human complicated pregnancies, were induced by microsphere embolization of the placental bed (embolization model, 7 lamb fetuses, 370 Doppler recordings) or by fetal hemodilution (anemia model, 4 lamb fetuses, 184 recordings). A subjective 11-step operator auditory scale (OAS) was related to conventional Doppler parameters, PI and time average mean velocity (TAM), and to sound frequency analysis of Doppler signals (sound frequency with the maximum energy content [MAXpeak] and frequency band at maximum level minus 15 dB [MAXpeak-15 dB] over several heart cycles). Results We found a negative correlation between the OAS and PI: median Rho −0.73 (range −0.35– −0.94) and −0.68 (range −0.57– −0.78) in the two lamb models, respectively. There was a positive correlation between OAS and TAM in both models: median Rho 0.80 (range 0.58–0.95) and 0.90 (range 0.78–0.95), respectively. A strong correlation was found between TAM and the results of sound spectrum analysis; in the embolization model the median r was 0.91 (range 0.88–0.97) for MAXpeak and 0.91 (range 0.82–0.98) for MAXpeak-15 dB. In the anemia model, the corresponding values were 0.92 (range 0.78–0.96) and 0.96 (range 0.89–0.98), respectively. Conclusion Audio-spectrum analysis reflects the subjective perception of Doppler sound signals in the umbilical artery and has a strong correlation to TAM-velocity. This information might be of importance for clinical management of complicated pregnancies as an addition to conventional Doppler parameters

  19. Spectral color Doppler in the diagnosis and follow-up of Graves' disease

    Hyperthyroidism in Graves' disease is caused by the presence of circulating autoantibodies to the THS receptors on the thyroid cells. Thyroid-suppression therapy prevents hormone production directly, without affecting the pathogenetic process. They performed color Doppler US of the thyroid gland and pulsed Doppler analysis of thyroid artery flow in 21 patients with Graves' disease before and during medical treatment. US results were compared with those of a control group of 40 healthy subjects and correlated with the values of thyroid hormones, TSH and thyroid microsomal and thyroglobulin antibodies. The thyroid gland was hypo vascularized in the control group. Pulsed Doppler examination of the thyroid arteries exhibited peak systolic velocity of PSV 20 ± 4 cm/s, diastolic velocity of 8 ± 1 cm/s, and resistive index of 0.60 ± 0.04. The thyroid gland of Graves' disease patients was hyper vascularized. Pulsed Doppler examination of the thyroid arteries exhibited peak systolic velocity (PSV = 51 ± 12 cm/s), end diastolic velocity (VD = 15 ± 4 cm/s) and resistive index (RI = 0.71 ± 0.04) significantly higher than in normal subjects (p < 0.001). Circulating thyroid hormones and flow parameters normalized after 6-8 months of medical therapy (PSV = 20 ± 6 cm/s, VD = 9 ± 3 cm(s, RI = 0.58 ± 0.07). The color Doppler patterns normalized only in a patient with normal TSH and antibodies. Sampling of the thyroid arteries proved more repeatable than sampling of parenchymal vessels

  20. Left Ventricular Diastolic Dysfunction Assessed by Conventional Echocardiography and Spectral Tissue Doppler Imaging in Adolescents With Arterial Hypertension.

    Morka, Aleksandra; Szydlowski, Leslaw; Moric-Janiszewska, Ewa; Mazurek, Boguslaw; Markiewicz-Loskot, Grazyna; Stec, Sebastian

    2016-02-01

    Compared to conventional echocardiography, spectral tissue Doppler imaging (s-TDI) allows more precise evaluation of diastolic cardiac function. The purpose of this study was to conduct s-TDI to analyze the slow movement of the left ventricular (LV) myocardium in adolescents with systemic arterial hypertension (HT) and to determine whether patients with HT suffer from LV diastolic dysfunction. The study group comprised 69 consecutive patients (48 boys and 21 girls aged 14-17 years [mean, 15.5 ± 1.1 years]) with primary HT, and the control group comprised 48 healthy participants (24 boys and 24 girls aged 14-17 years [mean, 15.8 ± 1.3 years]). Physical examinations, 24-hour arterial blood pressure monitoring, conventional 2-dimensional and Doppler echocardiography, and s-TDIs were performed. Analysis revealed that study group participants were significantly heavier and had greater LV mass indices than controls (P annuli during examination.Changes in the myocardium appear similar to those seen in adults. PMID:26937911

  1. Assessment of Normal Vertebral Arteries Vs. Normal Internal Carotid and Common Carotid Arteries Blood Flow Spectral Doppler Indices

    Sh. Sharif Kashani

    2005-08-01

    Full Text Available Introduction & Background: Vertebrobasilar insufficiency is the main cause of cerebrovascular accidents (CVAs in 20% of cases. There are few reports regarding spectral Doppler indices (SDIs of vertebral arteries (VAs normal blood flow. The objective of this study is to provide basic reference data about SDIs of VAs nor-mal blood flow separately, and in comparison with internal and common carotid arteries (ICAs and CCAs normal blood flows SDIs, for better and earlier detection of disordered SDIs of these arteries blood flow. Patients & Methods: This cross-sectional study was performed in Amir Alam hospital by three radiologists ex-perienced in vascular color Doppler sonography (CDS and spectral Doppler sonography (SDS from February 2002 till March 2004, on 70 normal patients. CDS and SDS of right and left vertebral arteries (RVA and LVA, right and left common carotid arteries (RCCA and LCCA, and right and left internal carotid arteries (RICA and LICA were performed. SDIs consisted of peak systolic velocity (PSV, end- diastolic velocity (EDV, and resistive index (RI values of these arteries blood flows and were assessed and compared with one another. Fi-nally all data was collected in SPSS version 12 software, and analyzed with the Student's T-test. Results: In this study, the mean PSV, EDV, and RI values of RVA blood flow were respectively 41.60 ± 9.6 cm/s, 14.60 ± 3.7 cm/s and 0.65 ± 0.06; the mean PSV, EDV and RI values of LVA blood flow were respectively 42.20 ± 10.2 cm/s, 15.20 ± 4.2 cm/s, and 0.64 ± 0.05. There was not statistically significant difference between the mean PSV, EDV, and RI values of RVA and LVA blood flows (P value > 0.1. The mean PSV and EDV val-ues of VAs blood flows were significantly lower than the mean PSV and EDV values of CCAs and ICCAs blood flows respectively (p-value 0.05.

  2. Adaptive camouflage in the VIS and IR spectral range: main principles and mechanisms

    Schwarz, Alexander

    2015-10-01

    This paper presents a survey of main applicable technical principles and mechanisms for adaptive camouflage in the visible (VIS) and infrared (IR) spectral ranges. All principles are described by their operation method and technical data such as the active spectral range, the degree and speed of adaptation, weight, power consumption, robustness, usability, lifetime, technology readiness level (TRL) etc.. The paper allows to compare the different principles and to assess them with regard to an application to an adaptive camouflage system.

  3. Experimental demonstration of an adaptive architecture for direct spectral imaging classification.

    Dunlop-Gray, Matthew; Poon, Phillip K; Golish, Dathon; Vera, Esteban; Gehm, Michael E

    2016-08-01

    Spectral imaging is a powerful tool for providing in situ material classification across a spatial scene. Typically, spectral imaging analyses are interested in classification, though often the classification is performed only after reconstruction of the spectral datacube. We present a computational spectral imaging system, the Adaptive Feature-Specific Spectral Imaging Classifier (AFSSI-C), which yields direct classification across the spatial scene without reconstruction of the source datacube. With a dual disperser architecture and a programmable spatial light modulator, the AFSSI-C measures specific projections of the spectral datacube which are generated by an adaptive Bayesian classification and feature design framework. We experimentally demonstrate multiple order-of-magnitude improvement of classification accuracy in low signal-to-noise (SNR) environments when compared to legacy spectral imaging systems. PMID:27505794

  4. An adaptive demodulation approach for bearing fault detection based on adaptive wavelet filtering and spectral subtraction

    Fault diagnosis of rolling element bearings is important for improving mechanical system reliability and performance. Vibration signals contain a wealth of complex information useful for state monitoring and fault diagnosis. However, any fault-related impulses in the original signal are often severely tainted by various noises and the interfering vibrations caused by other machine elements. Narrow-band amplitude demodulation has been an effective technique to detect bearing faults by identifying bearing fault characteristic frequencies. To achieve this, the key step is to remove the corrupting noise and interference, and to enhance the weak signatures of the bearing fault. In this paper, a new method based on adaptive wavelet filtering and spectral subtraction is proposed for fault diagnosis in bearings. First, to eliminate the frequency associated with interfering vibrations, the vibration signal is bandpass filtered with a Morlet wavelet filter whose parameters (i.e. center frequency and bandwidth) are selected in separate steps. An alternative and efficient method of determining the center frequency is proposed that utilizes the statistical information contained in the production functions (PFs). The bandwidth parameter is optimized using a local ‘greedy’ scheme along with Shannon wavelet entropy criterion. Then, to further reduce the residual in-band noise in the filtered signal, a spectral subtraction procedure is elaborated after wavelet filtering. Instead of resorting to a reference signal as in the majority of papers in the literature, the new method estimates the power spectral density of the in-band noise from the associated PF. The effectiveness of the proposed method is validated using simulated data, test rig data, and vibration data recorded from the transmission system of a helicopter. The experimental results and comparisons with other methods indicate that the proposed method is an effective approach to detecting the fault-related impulses

  5. An adaptive demodulation approach for bearing fault detection based on adaptive wavelet filtering and spectral subtraction

    Zhang, Yan; Tang, Baoping; Liu, Ziran; Chen, Rengxiang

    2016-02-01

    Fault diagnosis of rolling element bearings is important for improving mechanical system reliability and performance. Vibration signals contain a wealth of complex information useful for state monitoring and fault diagnosis. However, any fault-related impulses in the original signal are often severely tainted by various noises and the interfering vibrations caused by other machine elements. Narrow-band amplitude demodulation has been an effective technique to detect bearing faults by identifying bearing fault characteristic frequencies. To achieve this, the key step is to remove the corrupting noise and interference, and to enhance the weak signatures of the bearing fault. In this paper, a new method based on adaptive wavelet filtering and spectral subtraction is proposed for fault diagnosis in bearings. First, to eliminate the frequency associated with interfering vibrations, the vibration signal is bandpass filtered with a Morlet wavelet filter whose parameters (i.e. center frequency and bandwidth) are selected in separate steps. An alternative and efficient method of determining the center frequency is proposed that utilizes the statistical information contained in the production functions (PFs). The bandwidth parameter is optimized using a local ‘greedy’ scheme along with Shannon wavelet entropy criterion. Then, to further reduce the residual in-band noise in the filtered signal, a spectral subtraction procedure is elaborated after wavelet filtering. Instead of resorting to a reference signal as in the majority of papers in the literature, the new method estimates the power spectral density of the in-band noise from the associated PF. The effectiveness of the proposed method is validated using simulated data, test rig data, and vibration data recorded from the transmission system of a helicopter. The experimental results and comparisons with other methods indicate that the proposed method is an effective approach to detecting the fault-related impulses

  6. Fast Spectral Velocity Estimation Using Adaptive Techniques: In-Vivo Results

    Gran, Fredrik; Jakobsson, Andreas; Udesen, Jesper; Jensen, Jørgen Arendt

    Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation window(OW) is very sbort. In this paper two adaptive techniques are tested and compared to the averaged perlodogram (Welch) for blood velocity estimation. The Blood Power...... spectral Capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slowtime and depth. The Blood Amplitude and Phase Estimation technique (BAPES) is based on finding a set of matched filters (one for each velocity component of interest) and filtering...... the blood process over slow-time and averaging over depth to find the power spectral density estimate. In this paper, the two adaptive methods are explained, and performance Is assessed in controlled steady How experiments and in-vivo measurements. The three methods were tested on a circulating How...

  7. A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars

    Villain, J.-P.; André, R; M. Pinnock; R. A. Greenwald; Hanuise, C.

    2002-01-01

    The HF radars of the Super Dual Auroral Radar Network (SuperDARN) provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Perio...

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

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

    2007-09-01

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

  9. Seeing Beyond Sight: The Adaptive, Feature-Specific, Spectral Imaging Classifier

    Dunlop-Gray, Matthew John

    Spectral imaging, a combination of spectroscopy and imaging, is a powerful tool for providing in situ material classification across a spatial scene. Typically spectral imaging analyses are interested in classification, though conventionally the classification is performed only after reconstruction of the spectral datacube, which can have upwards of 109 signal elements. In this dissertation, I present a computational spectral imaging system, the Adaptive Feature-Specific Spectral Imaging Classifier (AFSSI-C), which yields direct classification across the spatial scene without reconstruction of the source datacube. With a dual disperser architecture and a programmable spatial light modulator which induces spectral filtering, the AFSSI-C measures specific projections of the spectral datacube which in turn feed an adaptive Bayesian classification and feature design framework. I present my work related to the design, construction, and testing of this instrument, which ultimately demonstrated significantly improved classification accuracy compared to legacy spectral imaging systems by first showing agreement with simulation, and then comparing to expected performance of traditional systems. As a result of its open aperture and adaptive filters, the AFSSI-C achieves 250x better accuracy than pushbroom, whiskbroom, and tunable filter systems for a four-class problem at 0 dB TSNR (task signal-to-noise ratio)---a point where measurement noise is equal to the minimum separation between the library spectra. The AFSSI-C also achieves 100x better accuracy than random projections at 0 dB TSNR.

  10. Usefulness of resistive index on spectral Doppler ultrasonography in the detection of renal cell carcinoma in patients with end-stage renal disease

    The aim of this study was to explore the usefulness of the resistive index (RI) on spectral Doppler ultrasonography (US) in the detection of renal cell carcinoma (RCC) in patients with end-stage renal disease (ESRD). Seventeen ESRD patients with kidneys in which renal masses were suspected in routine US were subjected. They underwent computed tomography scans and additional Doppler US for the characterization of the detected lesions. All underwent radical nephrectomy with the suspicion of RCC. Fourteen patients finally were included. RI measurements were conducted in the region of the suspected renal mass and the background renal parenchyma. The intra class correlation coefficient was used to assess the reproducibility of the RI measurement. A paired t-test was used to compare the RI values between the renal mass and the background renal parenchyma (P<0.05). The RI values measured at the RCCs were significantly lower than those measured at the background renal parenchyma (0.41-0.65 vs. 0.75-0.89; P<0.001). The intrareader reproducibility proved to be excellent and good for the renal masses and the parenchyma, respectively (P<0.001). RI on spectral Doppler US is useful in detecting RCC in patients with ESRD. The RI values measured at the RCCs were significantly lower than those measured at the background renal parenchyma.

  11. Usefulness of resistive index on spectral Doppler ultrasonography in the detection of renal cell carcinoma in patients with end-stage renal disease

    Kim, Sang Youn; Woo, Sung Min; Cho, Jeong Yeon; Kim, Seung Hyup [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of); Hwang, Sung Il; Lee, Hak Jong [Dept. of Radiology, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Moon, Min Hoan; Sung, Chang Kyu [Dept. of adiology, Seoul National University Boramae Hospital, Seoul (Korea, Republic of)

    2014-04-15

    The aim of this study was to explore the usefulness of the resistive index (RI) on spectral Doppler ultrasonography (US) in the detection of renal cell carcinoma (RCC) in patients with end-stage renal disease (ESRD). Seventeen ESRD patients with kidneys in which renal masses were suspected in routine US were subjected. They underwent computed tomography scans and additional Doppler US for the characterization of the detected lesions. All underwent radical nephrectomy with the suspicion of RCC. Fourteen patients finally were included. RI measurements were conducted in the region of the suspected renal mass and the background renal parenchyma. The intra class correlation coefficient was used to assess the reproducibility of the RI measurement. A paired t-test was used to compare the RI values between the renal mass and the background renal parenchyma (P<0.05). The RI values measured at the RCCs were significantly lower than those measured at the background renal parenchyma (0.41-0.65 vs. 0.75-0.89; P<0.001). The intrareader reproducibility proved to be excellent and good for the renal masses and the parenchyma, respectively (P<0.001). RI on spectral Doppler US is useful in detecting RCC in patients with ESRD. The RI values measured at the RCCs were significantly lower than those measured at the background renal parenchyma.

  12. Adaptive clutter rejection filters for airborne Doppler weather radar applied to the detection of low altitude windshear

    Keel, Byron M.

    1989-01-01

    An optimum adaptive clutter rejection filter for use with airborne Doppler weather radar is presented. The radar system is being designed to operate at low-altitudes for the detection of windshear in an airport terminal area where ground clutter returns may mask the weather return. The coefficients of the adaptive clutter rejection filter are obtained using a complex form of a square root normalized recursive least squares lattice estimation algorithm which models the clutter return data as an autoregressive process. The normalized lattice structure implementation of the adaptive modeling process for determining the filter coefficients assures that the resulting coefficients will yield a stable filter and offers possible fixed point implementation. A 10th order FIR clutter rejection filter indexed by geographical location is designed through autoregressive modeling of simulated clutter data. Filtered data, containing simulated dry microburst and clutter return, are analyzed using pulse-pair estimation techniques. To measure the ability of the clutter rejection filters to remove the clutter, results are compared to pulse-pair estimates of windspeed within a simulated dry microburst without clutter. In the filter evaluation process, post-filtered pulse-pair width estimates and power levels are also used to measure the effectiveness of the filters. The results support the use of an adaptive clutter rejection filter for reducing the clutter induced bias in pulse-pair estimates of windspeed.

  13. A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars

    Villain, J.-P.; André, R.; Pinnock, M.; Greenwald, R. A.; Hanuise, C.

    2002-11-01

    The HF radars of the Super Dual Auroral Radar Network (SuperDARN) provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Period 1 corresponds to the winter months of 1994, while period 2 covers October 1996 to March 1997. The distributions of data points and average spectral width are presented as a function of Magnetic Latitude and Magnetic Local Time. The databases are very consistent and exhibit the same features. The most stringent features are: a region of very high spectral width, collocated with the ionospheric LLBL/cusp/mantle region; an oval shaped region of high spectral width, whose equator-ward boundary matches the poleward limit of the Holzworth and Meng auroral oval. A simulation has been conducted to evaluate the geometrical and instrumental effects on the spectral width. It shows that these effects cannot account for the observed spectral features. It is then concluded that these specific spectral width characteristics are the signature of ionospheric/magnetospheric coupling phenomena.

  14. A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars

    J.-P. Villain

    Full Text Available The HF radars of the Super Dual Auroral Radar Network (SuperDARN provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Period 1 corresponds to the winter months of 1994, while period 2 covers October 1996 to March 1997. The distributions of data points and average spectral width are presented as a function of Magnetic Latitude and Magnetic Local Time. The databases are very consistent and exhibit the same features. The most stringent features are: a region of very high spectral width, collocated with the ionospheric LLBL/cusp/mantle region; an oval shaped region of high spectral width, whose equator-ward boundary matches the poleward limit of the Holzworth and Meng auroral oval. A simulation has been conducted to evaluate the geometrical and instrumental effects on the spectral width. It shows that these effects cannot account for the observed spectral features. It is then concluded that these specific spectral width characteristics are the signature of ionospheric/magnetospheric coupling phenomena.

    Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; ionospheric irregularities

  15. An Adaptive Spectral Clustering Algorithm Based on the Importance of Shared Nearest Neighbors

    Xiaoqi He

    2015-05-01

    Full Text Available The construction of a similarity matrix is one significant step for the spectral clustering algorithm; while the Gaussian kernel function is one of the most common measures for constructing the similarity matrix. However, with a fixed scaling parameter, the similarity between two data points is not adaptive and appropriate for multi-scale datasets. In this paper, through quantitating the value of the importance for each vertex of the similarity graph, the Gaussian kernel function is scaled, and an adaptive Gaussian kernel similarity measure is proposed. Then, an adaptive spectral clustering algorithm is gotten based on the importance of shared nearest neighbors. The idea is that the greater the importance of the shared neighbors between two vertexes, the more possible it is that these two vertexes belong to the same cluster; and the importance value of the shared neighbors is obtained with an iterative method, which considers both the local structural information and the distance similarity information, so as to improve the algorithm’s performance. Experimental results on different datasets show that our spectral clustering algorithm outperforms the other spectral clustering algorithms, such as the self-tuning spectral clustering and the adaptive spectral clustering based on shared nearest neighbors in clustering accuracy on most datasets.

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

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

    2009-04-06

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

  17. The Role of Colour Doppler And Spectral Flow Analysis In Pregnancy Induced Hypertension: A Case Control Study

    Hinal Bhagat

    2015-03-01

    Full Text Available Background: The use of Doppler ultrasound to study blood flow in Obstetrics is of major importance because fetal inaccessibility precludes many other methods of study of fetal circulation. This study was undertaken to assess the role of Doppler in management of Pregnancy induced Hypertension. Methodology: The present case-control study was conducted in the department of Radiology, Govt. Medical College and New Civil Hospital, Surat. Details of obstetric history, age, last menstrual date and underlying risk factor, Doppler study of umbilical artery, fetal middle cerebral artery, both maternal uterine arteries and Ductus venosus was done. Parameters in form of Resistive index (RI, Pulsatility index (PI and systolic/diastolic ratio (S/D of all four arteries were taken. Results: It was observed that 55% cases with pregnancy induced hypertension developed IUGR fetuses while 2% of the IUGR fetus was present in control group. There were 41 (54% cases with IUGR fetuses. Out of which 28 (68% cases with IUGR had fetoplacental Doppler abnormality. 13 cases had abnormally low PI of MCA with normal umbilical arterial Doppler indices, out of which 12 patients had abnormal fetal outcome. Conclusion: By examining the maternal vessels using Doppler ultrasound it is possible to determine, the risk of complication developing in the course of pregnancy long before clinical signs of preeclampsia appear so that therapeutic measures may be undertaken early. [Natl J Med Res 2015; 5(1.000: 57-60

  18. Spectral saliency via automatic adaptive amplitude spectrum analysis

    Wang, Xiaodong; Dai, Jialun; Zhu, Yafei; Zheng, Haiyong; Qiao, Xiaoyan

    2016-03-01

    Suppressing nonsalient patterns by smoothing the amplitude spectrum at an appropriate scale has been shown to effectively detect the visual saliency in the frequency domain. Different filter scales are required for different types of salient objects. We observe that the optimal scale for smoothing amplitude spectrum shares a specific relation with the size of the salient region. Based on this observation and the bottom-up saliency detection characterized by spectrum scale-space analysis for natural images, we propose to detect visual saliency, especially with salient objects of different sizes and locations via automatic adaptive amplitude spectrum analysis. We not only provide a new criterion for automatic optimal scale selection but also reserve the saliency maps corresponding to different salient objects with meaningful saliency information by adaptive weighted combination. The performance of quantitative and qualitative comparisons is evaluated by three different kinds of metrics on the four most widely used datasets and one up-to-date large-scale dataset. The experimental results validate that our method outperforms the existing state-of-the-art saliency models for predicting human eye fixations in terms of accuracy and robustness.

  19. Adaptive Haar wavelets for the angular discretisation of spectral wave models

    Adam, Alexandros; Buchan, Andrew G.; Piggott, Matthew D.; Pain, Christopher C.; Hill, Jon; Goffin, Mark A.

    2016-01-01

    A new framework for applying anisotropic angular adaptivity in spectral wave modelling is presented. The angular dimension of the action balance equation is discretised with the use of Haar wavelets, hierarchical piecewise-constant basis functions with compact support, and an adaptive methodology for anisotropically adjusting the resolution of the angular mesh is proposed. This work allows a reduction of computational effort in spectral wave modelling, through a reduction in the degrees of freedom required for a given accuracy, with an automated procedure and minimal cost.

  20. An Adaptive Clutter Suppression Technique for Moving Target Detector in Pulse Doppler Radar

    A. Mandal

    2014-04-01

    Full Text Available An adaptive system performs the processing by using an architecture having time-varying parameters on the received signals which accompanies with clutters. In this paper, an adaptive moving target detector has been designed to meet the challenges of target detection amidst various levels of clutter environments. The approach has been used that is able to overcome the inherent limitations of conventional systems (e.g. Moving Target Indicator, Fast Fourier Transform etc. having predefined coefficients. In this purpose an optimal design of transversal filter is being proposed along with various weight selection Maps to improve probability of detection in ground based surveillance radar. A modified LMS algorithm based adaptive FIR filter has been implemented utilizing modular CORDIC unit as a main processing element for filtering as well as weight updatation to suppress clutter of various intensity. Extensive MATLAB simulations have been done using various levels of clutter input to show the effectiveness of adaptive moving target detector (AMTD.

  1. Spectral Efficiency Optimization for an Interfering Cognitive Radio with Adaptive Modulation and Coding

    Taki, Mehrdad

    2009-01-01

    In this paper, we consider a primary and a cognitive user transmitting over a wireless fading interference channel. The primary user transmits with a constant power and utilizes an adaptive modulation and coding (AMC) scheme satisfying a bit error rate requirement. We propose a link adaptation scheme to maximize the average spectral efficiency of the cognitive radio, while a minimum required spectral efficiency for the primary user is provisioned. The resulting problem is constrained to also satisfy a bit error rate requirement and a power constraint for the cognitive link. The AMC mode selection and power control at the cognitive transmitter is optimized based on the modified signal to noise plus interference ratio feedback of both links. The problem is then cast as a nonlinear discrete optimization problem for which a fast and efficient suboptimum solution is presented. We also present a scheme with rate adaptive and constant power cognitive radio. An important characteristic of the proposed schemes is that...

  2. Adaptive mesh refinement with spectral accuracy for magnetohydrodynamics in two space dimensions

    We examine the effect of accuracy of high-order spectral element methods, with or without adaptive mesh refinement (AMR), in the context of a classical configuration of magnetic reconnection in two space dimensions, the so-called Orszag-Tang (OT) vortex made up of a magnetic X-point centred on a stagnation point of the velocity. A recently developed spectral-element adaptive refinement incompressible magnetohydrodynamic (MHD) code is applied to simulate this problem. The MHD solver is explicit, and uses the Elsaesser formulation on high-order elements. It automatically takes advantage of the adaptive grid mechanics that have been described elsewhere in the fluid context (Rosenberg et al 2006 J. Comput. Phys. 215 59-80); the code allows both statically refined and dynamically refined grids. Tests of the algorithm using analytic solutions are described, and comparisons of the OT solutions with pseudo-spectral computations are performed. We demonstrate for moderate Reynolds numbers that the algorithms using both static and refined grids reproduce the pseudo-spectral solutions quite well. We show that low-order truncation-even with a comparable number of global degrees of freedom-fails to correctly model some strong (sup-norm) quantities in this problem, even though it satisfies adequately the weak (integrated) balance diagnostics

  3. Adaptive Airborne Doppler Wind Lidar Beam Scanning Patterns for Complex Terrain and Small Scale Organized Atmospheric Structure Observations

    Emmitt, G.; O'Handley, C.; de Wekker, S. F.

    2008-12-01

    The conical scan is the traditional pattern used to obtain vertical profiles of the wind field with an airborne Doppler wind lidar. Nadir or zenith pointing scanning wedges are ideal for this type of scan. A bi-axis scanner has been operated on a Navy Twin Otter for more than 6 years and has been recently installed on a Navy P3 for use in a field experiment to study typhoons. The bi-axis scanner enables a broad range of scanning patterns. A subset of the possible patterns is critical to obtaining useful wind profiles in the presence of complex terrain or small (~ 100's of meters) organized atmospheric structures (rolls, updrafts, waves, etc). Several scanning strategies have been tested in flights over the Monterey Peninsula and within tropical cyclones. Combined with Google Earth (on-board) and satellite imagery overlays, new realtime adaptive scanning algorithms are being developed and tested. The results of these tests (both real and simulated) will be presented in the form of case studies.

  4. Spectral Analysis of Vibrational Harmonic Motion by use of a Continuous-Wave CO2 Doppler Lidar

    Jarzembski, Maurice A.; Srivastava, Vandana

    1999-01-01

    Vibrational motion of a harmonic oscillator was investigated using a focused continuous wave CO2 Doppler lidar at 9.1 microns wavelength. A continuum of frequencies along with many discrete, equally spaced, resonant frequency modes was observed. The frequency modes are similar in structure to the oscillatory longitudinal modes of a laser cavity and arise because of interference of the natural resonant frequency of the oscillator with specific frequencies within the continuum. The spectra revealed departures from linear motion for vigorous vibrations of the oscillator. Each consecutive resonant frequency mode occurred for a movement of the oscillator much less than the wavelength of incident lidar radiation.

  5. A spectrally efficient detect-and-forward scheme with two-tier adaptive cooperation

    Benjillali, Mustapha

    2011-09-01

    We propose a simple relay-based adaptive cooperation scheme to improve the spectral efficiency of "Detect-and-Forward" (DetF) half-duplex relaying in fading channels. In a new common framework, we show that the proposed scheme offers considerable gainsin terms of the achievable information ratescompared to conventional DetF relaying schemes for both orthogonal and non-orthogonal source/relay transmissions. The analysis leads on to a general adaptive cooperation strategy based on the maximization of information rates at the destination which needs to observe only the average signal-to-noise ratios of the links. © 2006 IEEE.

  6. Adaptive two-stage Karhunen-Loeve-transform scheme for spectral decorrelation in hyperspectral bandwidth compression

    Saghri, John A.

    2010-05-01

    A computationally efficient adaptive two-stage Karhunen-Loeve transform (KLT) scheme for spectral decorrelation in hyperspectral lossy bandwidth compression is presented. The component decorrelation of the JPEG 2000 (extension 2) is replaced with an adaptive two-stage KLT scheme. The data are partitioned into small subsets. The spectral correlation within each partition is removed via a first-stage KLT. The interpartition spectral correlation is removed using a second-stage KLT applied to the resulting top few sets of equilevel principal component (PC) images. Since only a fraction of each equilevel first-stage PC images are used in the second stage, the KLT transformation matrices will have smaller sizes, leading to further improvement in computational complexity and coding efficiency. The computation of the proposed approach is parametrically quantified. It is shown that reconstructed image quality, as measured via statistical and/or machine-based exploitation measures, is improved by using a smaller partition size in the first-stage KLT. A criterion based on the components of the eigenvectors of the cross-covariance matrix is established to select first-stage PC images, which are used in the second-stage KLT. The proposed scheme also reduces the overhead bits required to transmit the covariance information to the receiver in conjunction with the coding bitstream.

  7. Spatially adaptive hp refinement approach for PN neutron transport equation using spectral element method

    Highlights: • Powerful hp-SEM refinement approach for PN neutron transport equation has been presented. • The method provides great geometrical flexibility and lower computational cost. • There is a capability of using arbitrary high order and non uniform meshes. • Both posteriori and priori local error estimation approaches have been employed. • High accurate results are compared against other common adaptive and uniform grids. - Abstract: In this work we presented the adaptive hp-SEM approach which is obtained from the incorporation of Spectral Element Method (SEM) and adaptive hp refinement. The SEM nodal discretization and hp adaptive grid-refinement for even-parity Boltzmann neutron transport equation creates powerful grid refinement approach with high accuracy solutions. In this regard a computer code has been developed to solve multi-group neutron transport equation in one-dimensional geometry using even-parity transport theory. The spatial dependence of flux has been developed via SEM method with Lobatto orthogonal polynomial. Two commonly error estimation approaches, the posteriori and the priori has been implemented. The incorporation of SEM nodal discretization method and adaptive hp grid refinement leads to high accurate solutions. Coarser meshes efficiency and significant reduction of computer program runtime in comparison with other common refining methods and uniform meshing approaches is tested along several well-known transport benchmarks

  8. The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar

    Baxa, Ernest G., Jr.; Lee, Jonggil

    1991-01-01

    The pulse pair method for spectrum parameter estimation is commonly used in pulse Doppler weather radar signal processing since it is economical to implement and can be shown to be a maximum likelihood estimator. With the use of airborne weather radar for windshear detection, the turbulent weather and strong ground clutter return spectrum differs from that assumed in its derivation, so the performance robustness of the pulse pair technique must be understood. Here, the effect of radar system pulse to pulse phase jitter and signal spectrum skew on the pulse pair algorithm performance is discussed. Phase jitter effect may be significant when the weather return signal to clutter ratio is very low and clutter rejection filtering is attempted. The analysis can be used to develop design specifications for airborne radar system phase stability. It is also shown that the weather return spectrum skew can cause a significant bias in the pulse pair mean windspeed estimates, and that the poly pulse pair algorithm can reduce this bias. It is suggested that use of a spectrum mode estimator may be more appropriate in characterizing the windspeed within a radar range resolution cell for detection of hazardous windspeed gradients.

  9. Mission-adaptable narrowband tunable imaging spectrometer (MANTIS): tactical spectral sensing

    Dirbas, Joseph; Mireles, Tony; Schoonmaker, Jon; Bush, Andy

    2004-08-01

    A series of low cost, light weight, mission-adaptable multispectral imaging spectrometers have been developed by PAR Government Systems Corporation (PGSC), utilizing mass-produced commercial off-the-shelf (COTS) components. The developed MANTIS sensors have been used to collect continuous multispectral data for mine counter measures (MCM) and intelligence, surveillance, and reconnaissance (ISR) applications aboard low cost manned aircraft platforms. Each MANTIS system images four spectral bands simultaneously. The four user-selectable spectral filters are inserted into an easily accessible filter cartridge supporting pre-flight filter selection. Data acquisition is accomplished by COTS frame grabbers installed in a Pentium based personal computer and all digitized data is written in real-time to a redundant array of independent disks (RAID). PGSC has also developed a graphical user interface providing control, display and recording options. The MANTIS approach and simple design lends itself to low-cost modifications and improvements.

  10. A spectral identification technique for adaptive attitude control and pointing of the Space Telescope

    Teuber, D. L.

    1976-01-01

    The Space Telescope is a 2.4 m class aperture optical telescope having near-diffraction-limited performance. It will be placed into earth orbit by 1980 via the Space Shuttle. The problem considered is how to achieve negligible degradation of the astronomy imaging capability (to 0.005 arc second) due to smearing by pointing motions during observations. Initially, pointing instability sources were identified and a linear stability was used to assess the magnitude of elastic body modes and to design control system compensation regions necessary for subsequent adaptive control. A spectral identification technique for this adaptive attitude control and pointing has been investigated that will alleviate requirements for comprehensive dynamic ground testing. Typical all-digital simulation results describing motions of the telescope line of sight are presented.

  11. Spectral Efficiency of Multiple Access Fading Channels with Adaptive Interference Cancellation

    Shakya, Indu L

    2012-01-01

    Reliable estimation of users' channels and data in rapidly time varying fading environments is a very challenging task of multiuser detection (MUD) techniques that promise impressive capacity gains for interference limited systems such as non-orthogonal CDMA and spatial multiplexing MIMO based LTE. This paper analyzes relative channel estimation error performances of conventional single user and multiuser receivers for an uplink of DS-CDMA and shows their impact on output signal to interference and noise ratio (SINR) performances. Mean squared error (MSE) of channel estimation and achievable spectral efficiencies of these receivers obtained from the output SINR calculations are then compared with that achieved with new adaptive interference canceling receivers. It is shown that the adaptive receivers using successive (SIC) and parallel interference cancellation (PIC) methods offer much improved channel estimation and SINR performances, and hence significant increase in achievable sum date rates.

  12. Improved spectral kurtosis with adaptive redundant multiwavelet packet and its applications for rotating machinery fault detection

    Rotating machinery fault detection is significant to avoid serious accidents and huge economic losses effectively. However, due to the vibration signal with the character of non-stationarity and nonlinearity, the detection and extraction of the fault feature turn into a challenging task. Therefore, a novel method called improved spectral kurtosis (ISK) with adaptive redundant multiwavelet packet (ARMP) is proposed for this task. Spectral kurtosis (SK) has been proved to be a powerful tool to detect and characterize the non-stationary signal. To improve the SK in filter limitation and enhance the resolution of spectral analysis as well as match fault feature optimally, the ARMP is introduced into the SK. Moreover, since kurtosis does not reflect the actual trend of periodic impulses, the SK is improved by incorporating an evaluation index called envelope spectrum entropy as supplement. The proposed method is applied to the rolling element bearing and gear fault detection to validate its reliability and effectiveness. Compared with the conventional frequency spectrum, envelope spectrum, original SK and some single wavelet methods, the results indicate that it could improve the accuracy of frequency-band selection and enhance the ability of rotating machinery fault detection. (paper)

  13. The use of the spectral method within the fast adaptive composite grid method

    McKay, S.M.

    1994-12-31

    The use of efficient algorithms for the solution of partial differential equations has been sought for many years. The fast adaptive composite grid (FAC) method combines an efficient algorithm with high accuracy to obtain low cost solutions to partial differential equations. The FAC method achieves fast solution by combining solutions on different grids with varying discretizations and using multigrid like techniques to find fast solution. Recently, the continuous FAC (CFAC) method has been developed which utilizes an analytic solution within a subdomain to iterate to a solution of the problem. This has been shown to achieve excellent results when the analytic solution can be found. The CFAC method will be extended to allow solvers which construct a function for the solution, e.g., spectral and finite element methods. In this discussion, the spectral methods will be used to provide a fast, accurate solution to the partial differential equation. As spectral methods are more accurate than finite difference methods, the ensuing accuracy from this hybrid method outside of the subdomain will be investigated.

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

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

    2012-06-01

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

  15. The development of a combined b-mode, ARFI, and spectral Doppler ultrasound imaging system for investigating cardiovascular stiffness and hemodynamics

    Doherty, Joshua R.; Dumont, Douglas M.; Trahey, Gregg E.

    2011-03-01

    The progression of atherosclerotic disease, caused by the formation of plaques within arteries, is a complex process believed to be a function of the localized mechanical properties and hemodynamic loading associated with the arterial wall. It is hypothesized that measurements of vascular stiffness and wall-shear rate (WSR) may provide important information regarding vascular remodeling, endothelial function, and the growth of soft-lipid filled plaques that could help a clinician better diagnose a patient's risk of clinical events such as stroke. To that end, the approach taken in this work was to combine conventional B-mode, Acoustic Radiation Force Impulse (ARFI), Shear Wave Elasticity Imaging (SWEI), and spectral Doppler techniques into a single imaging system capable of simultaneously measuring the tissue displacements and WSR throughout the cardiac cycle and over several heartbeats. Implemented on a conventional scanner, the carotid arteries of human subjects were scanned to demonstrate the initial in vivo feasibility of the method. Two non-invasive ultrasound based imaging methods, SAD-SWEI and SAD-Gated Imaging, were developed that measure ARF-induced on-axis tissue displacements, off-axis transverse wave velocities, and WSR throughout the cardiac cycle. Human carotid artery scans were performed in vivo on 5 healthy subjects. Statistical differences were observed in both on-axis proximal wall displacements and transverse wave velocities during diastole compared to systole.

  16. Spectrally resolved bioluminescence tomography with adaptive finite element analysis: methodology and simulation

    As a molecular imaging technique, bioluminescence tomography (BLT) with its highly sensitive detection and facile operation can significantly reveal molecular and cellular information in vivo at the whole-body small animal level. However, because of complex photon transportation in biological tissue and boundary detection data with high noise, bioluminescent sources in deeper positions generally cannot be localized. In our previous work, we used achromatic or monochromatic measurements and an a priori permissible source region strategy to develop a multilevel adaptive finite-element algorithm. In this paper, we propose a spectrally solved tomographic algorithm with a posteriori permissible source region selection. Multispectral measurements, and anatomical and optical information first deal with the nonuniqueness of BLT and constrain the possible solution of source reconstruction. The use of adaptive mesh refinement and permissible source region based on a posteriori measures not only avoids the dimension disaster arising from the multispectral measured data but also reduces the ill-posedness of BLT and therefore improves the reconstruction quality. Reconsideration of the optimization method and related modifications further enhance reconstruction robustness and efficiency. We also incorporate into the method some improvements for reducing computational burdens. Finally, using a whole-body virtual mouse phantom, we demonstrate the capability of the proposed BLT algorithm to reconstruct accurately bioluminescent sources in deeper positions. In terms of optical property errors and two sources of discernment in deeper positions, this BLT algorithm represents the unique predominance for BLT reconstruction

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

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

  18. Doppler ion program description

    The Doppler spectrometer is a conventional Czerny-Turner grating spectrometer with a 1024 channel multiple detector. Light is dispersed across the detector, and its output yields a spectrum covering approximately 200 A. The width of the spectral peak is directly proportional to the temperature of the emitting ions, and determination of the impurity ion temperature allows one to infer the plasma ion temperature. The Doppler ion software system developed at General Atomic uses a TRACOR Northern 1710-31 and an LSI-11/2. The exact configuration of Doublet III is different from TRACOR Northern systems at other facilities

  19. Carotid Artery Doppler Assessment In Patients Accussed Of Strokes

    H. Mazaher; S. Sharif Kashani

    2005-01-01

    Carotid Doppler ultrasound assessment mostly indicated in patients accussed of TIAs or in younger patients with nonpersistant neurologic deficits. This assessment should be consisted of gray scale sonography, color Doppler Sonography, spectral Doppler sonography and power Doppler sonography. By gray scale sonography atherosclerotic plaques assessed from the point of Homogenousity, degree of echogenicity, surface regularity, calcification, length, Thichkness and sites of involvement. In color ...

  20. Photoreceptor processing speed and input resistance changes during light adaptation correlate with spectral class in the bumblebee, Bombus impatiens.

    Peter Skorupski

    Full Text Available Colour vision depends on comparison of signals from photoreceptors with different spectral sensitivities. However, response properties of photoreceptor cells may differ in ways other than spectral tuning. In insects, for example, broadband photoreceptors, with a major sensitivity peak in the green region of the spectrum (>500 nm, drive fast visual processes, which are largely blind to chromatic signals from more narrowly-tuned photoreceptors with peak sensitivities in the blue and UV regions of the spectrum. In addition, electrophysiological properties of the photoreceptor membrane may result in differences in response dynamics of photoreceptors of similar spectral class between species, and different spectral classes within a species. We used intracellular electrophysiological techniques to investigate response dynamics of the three spectral classes of photoreceptor underlying trichromatic colour vision in the bumblebee, Bombus impatiens, and we compare these with previously published data from a related species, Bombus terrestris. In both species, we found significantly faster responses in green, compared with blue- or UV-sensitive photoreceptors, although all 3 photoreceptor types are slower in B. impatiens than in B. terrestris. Integration times for light-adapted B. impatiens photoreceptors (estimated from impulse response half-width were 11.3 ± 1.6 ms for green photoreceptors compared with 18.6 ± 4.4 ms and 15.6 ± 4.4 for blue and UV, respectively. We also measured photoreceptor input resistance in dark- and light-adapted conditions. All photoreceptors showed a decrease in input resistance during light adaptation, but this decrease was considerably larger (declining to about 22% of the dark value in green photoreceptors, compared to blue and UV (41% and 49%, respectively. Our results suggest that the conductances associated with light adaptation are largest in green photoreceptors, contributing to their greater temporal processing speed

  1. Ultrasonic Doppler Modes

    Tortoli, Piero; Fidanzati, Paolo; Luca, Bassi

    Any US equipment includes Doppler facilities capable of providing information about moving structures inside the human body. In most cases, the primary interest is in the investigation of blood flow dynamics, since this may be helpful for early diagnosis of cardiovascular diseases. However, there is also an increasing interest in tracking the movements of human tissues, since such movements can give an indirect evaluation of their elastic properties, which are valuable indicators of the possible presence of pathologies. This paper aims at presenting an overview of the different ways in which the Doppler technique has been developed and used in medical ultrasound (US), from early continuous wave (CW) systems to advanced pulsed wave (PW) colour-Doppler equipment. In particular, the most important technical features and clinical applications of CW, single-gate PW, multi-gate PW and flow-imaging systems are reviewed. The main signal processing approaches used for detection of Doppler frequencies are described, including time-domain and frequency-domain (spectral) methods, as well as novel strategies like, e.g., harmonic Doppler mode, which have been recently introduced to exploit the benefits of US contrast agents.

  2. Laser Doppler imaging, revisited

    Atlan, Michael; Gross, Michel

    2006-01-01

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

  3. Spectral Tuning of Killer Whale (Orcinus orca) Rhodopsin: Evidence for Positive Selection and Functional Adaptation in a Cetacean Visual Pigment.

    Dungan, Sarah Z; Kosyakov, Alexander; Chang, Belinda S W

    2016-02-01

    Cetaceans have undergone a remarkable evolutionary transition that was accompanied by many sensory adaptations, including modification of the visual system for underwater environments. Recent sequencing of cetacean genomes has made it possible to begin exploring the molecular basis of these adaptations. In this study we use in vitro expression methods to experimentally characterize the first step of the visual transduction cascade, the light activation of rhodopsin, for the killer whale. To investigate the spectral effects of amino acid substitutions thought to correspond with absorbance shifts relative to terrestrial mammals, we used the orca gene as a background for the first site-directed mutagenesis experiments in a cetacean rhodopsin. The S292A mutation had the largest effect, and was responsible for the majority of the spectral difference between killer whale and bovine (terrestrial) rhodopsin. Using codon-based likelihood models, we also found significant evidence for positive selection in cetacean rhodopsin sequences, including on spectral tuning sites we experimentally mutated. We then investigated patterns of ecological divergence that may be correlated with rhodopsin functional variation by using a series of clade models that partitioned the data set according to phylogeny, habitat, and foraging depth zone. Only the model partitioning according to depth was significant. This suggests that foraging dives might be a selective regime influencing cetacean rhodopsin divergence, and our experimental results indicate that spectral tuning may be playing an adaptive role in this process. Our study demonstrates that combining computational and experimental methods is crucial for gaining insight into the selection pressures underlying molecular evolution. PMID:26486871

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

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

    2016-05-01

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

  5. Evaluation of Cloud Microphysics Simulated using a Meso-Scale Model Coupled with a Spectral Bin Microphysical Scheme through Comparison with Observation Data by Ship-Borne Doppler and Space-Borne W-Band Radars

    Iguchi, T.; Nakajima, T.; Khain, A. P.; Saito, K.; Takemura, T.; Okamoto, H.; Nishizawa, T.; Tao, W.-K.

    2012-01-01

    Equivalent radar reflectivity factors (Ze) measured by W-band radars are directly compared with the corresponding values calculated from a three-dimensional non-hydrostatic meso-scale model coupled with a spectral-bin-microphysical (SBM) scheme for cloud. Three case studies are the objects of this research: one targets a part of ship-borne observation using 95 GHz Doppler radar over the Pacific Ocean near Japan in May 2001; other two are aimed at two short segments of space-borne observation by the cloud profiling radar on CloudSat in November 2006. The numerical weather prediction (NWP) simulations reproduce general features of vertical structures of Ze and Doppler velocity. A main problem in the reproducibility is an overestimation of Ze in ice cloud layers. A frequency analysis shows a strong correlation between ice water contents (IWC) and Ze in the simulation; this characteristic is similar to those shown in prior on-site studies. From comparing with the empirical correlations by the prior studies, the simulated Ze is overestimated than the corresponding values in the studies at the same IWC. Whereas the comparison of Doppler velocities suggests that large-size snowflakes are necessary for producing large velocities under the freezing level and hence rules out the possibility that an overestimation of snow size causes the overestimation of Ze. Based on the results of several sensitivity tests, we conclude that the source of the overestimation is a bias in the microphysical calculation of Ze or an overestimation of IWC. To identify the source of the problems needs further validation research with other follow-up observations.

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

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

    system exploits the direct relationship between arrival time of the received signal and range from the transducer. In the FM Doppler systems, a similar relationship exists in the spectral domain of the demodulated received signals, so that range is represented by frequency. Thus, a shift in location of...

  7. Current clinical applications of spectral tissue Doppler echocardiography (E/E' ratio as a noninvasive surrogate for left ventricular diastolic pressures in the diagnosis of heart failure with preserved left ventricular systolic function

    Roux Emmanuel

    2007-03-01

    Full Text Available Abstract Congestive heart failure with preserved left ventricular systolic function has emerged as a growing epidemic medical syndrome in developed countries, which is characterized by high morbidity and mortality rates. Rapid and accurate diagnosis of this condition is essential for optimizing the therapeutic management. The diagnosis of congestive heart failure is challenging in patients presenting without obvious left ventricular systolic dysfunction and additional diagnostic information is most commonly required in this setting. Comprehensive Doppler echocardiography is the single most useful diagnostic test recommended by the ESC and ACC/AHA guidelines for assessing left ventricular ejection fraction and cardiac abnormalities in patients with suspected congestive heart failure, and non-invasively determined basal or exercise-induced pulmonary capillary hypertension is likely to become a hallmark of congestive heart failure in symptomatic patients with preserved left ventricular systolic function. The present review will focus on the current clinical applications of spectral tissue Doppler echocardiography used as a reliable noninvasive surrogate for left ventricular diastolic pressures at rest as well as during exercise in the diagnosis of heart failure with preserved left ventricular systolic function. Chronic congestive heart failure, a disease of exercise, and acute heart failure syndromes are characterized by specific pathophysiologic and diagnostic issues, and these two clinical presentations will be discussed separately.

  8. Pseudo-spectral Maxwell solvers for an accurate modeling of Doppler harmonic generation on plasma mirrors with Particle-In-Cell codes

    Blaclard, G; Lehe, R; Vay, J L

    2016-01-01

    With the advent of PW class lasers, the very large laser intensities attainable on-target should enable the production of intense high order Doppler harmonics from relativistic laser-plasma mirrors interactions. At present, the modeling of these harmonics with Particle-In-Cell (PIC) codes is extremely challenging as it implies an accurate description of tens of harmonic orders on a a broad range of angles. In particular, we show here that standard Finite Difference Time Domain (FDTD) Maxwell solvers used in most PIC codes partly fail to model Doppler harmonic generation because they induce numerical dispersion of electromagnetic waves in vacuum which is responsible for a spurious angular deviation of harmonic beams. This effect was extensively studied and a simple toy-model based on Snell-Descartes law was developed that allows us to finely predict the angular deviation of harmonics depending on the spatio-temporal resolution and the Maxwell solver used in the simulations. Our model demonstrates that the miti...

  9. HyperSpectral classification with adaptively weighted L1-norm regularization and spatial postprocessing

    Aldea, Victor Stefan; Ahmad, M.O.; Lynch, W. E.

    2014-01-01

    Sparse regression methods have been proven effective in a wide range of signal processing problems such as image compression, speech coding, channel equalization, linear regression and classification. In this paper we develop a new method of hyperspectral image classification based on the sparse unmixing algorithm SUnSAL for which a pixel adaptive L1-norm regularization term is introduced. To further enhance class separability, the algorithm is kernelized using a RBF kernel and the final resu...

  10. Adaptive technique for matching the spectral response in skin lesions' images

    Pavlova, P.; Borisova, E.; Pavlova, E.; Avramov, L.

    2015-03-01

    The suggested technique is a subsequent stage for data obtaining from diffuse reflectance spectra and images of diseased tissue with a final aim of skin cancer diagnostics. Our previous work allows us to extract patterns for some types of skin cancer, as a ratio between spectra, obtained from healthy and diseased tissue in the range of 380 - 780 nm region. The authenticity of the patterns depends on the tested point into the area of lesion, and the resulting diagnose could also be fixed with some probability. In this work, two adaptations are implemented to localize pixels of the image lesion, where the reflectance spectrum corresponds to pattern. First adapts the standard to the personal patient and second - translates the spectrum white point basis to the relative white point of the image. Since the reflectance spectra and the image pixels are regarding to different white points, a correction of the compared colours is needed. The latest is done using a standard method for chromatic adaptation. The technique follows the steps below: -Calculation the colorimetric XYZ parameters for the initial white point, fixed by reflectance spectrum from healthy tissue; -Calculation the XYZ parameters for the distant white point on the base of image of nondiseased tissue; -Transformation the XYZ parameters for the test-spectrum by obtained matrix; -Finding the RGB values of the XYZ parameters for the test-spectrum according sRGB; Finally, the pixels of the lesion's image, corresponding to colour from the test-spectrum and particular diagnostic pattern are marked with a specific colour.

  11. Adaptation of the University of Wisconsin High Spectral Resolution Lidar for Polarization and Multiple Scattering Measurements

    Eloranta, E. W.; Piironen, P. K.

    1996-01-01

    Quantitative lidar measurements of aerosol scattering are hampered by the need for calibrations and the problem of correcting observed backscatter profiles for the effects of attenuation. The University of Wisconsin High Spectral Resolution Lidar (HSRL) addresses these problems by separating molecular scattering contributions from the aerosol scattering; the molecular scattering is then used as a calibration target that is available at each point in the observed profiles. While the HSRl approach has intrinsic advantages over competing techniques, realization of these advantages requires implementation of a technically demanding system which is potentially very sensitive to changes in temperature and mechanical alignments. This paper describes a new implementation of the HSRL in an instrumented van which allows measurements during field experiments. The HSRL was modified to measure depolarization. In addition, both the signal amplitude and depolarization variations with receiver field of view are simultaneously measured. This allows for discrimination of ice clouds from water clouds and observation of multiple scattering contributions to the lidar return.

  12. Time domain zero-padding based adaptive-PAM signal transmission with high spectral efficiency in IMDD optical communication system

    Zhang, Fangliu; He, Jing; Deng, Rui; Cheng, Yun; Xiao, Minlei; Chen, Lin

    2016-08-01

    In this paper, an adaptive pulse amplitude modulation (APAM) scheme is proposed and experimentally demonstrated in the intensity-modulation and direct-detection (IMDD) optical communications system. In the proposed scheme, the channel is divided into two sub-channels, and different PAM mapping can be chosen for different sub-channel according to the fading conditions. In addition, the 20-km standard single mode fiber (SSMF) transmission of 24 Gbit/s 16/4-APAM signal with the spectral efficiency (SE) up to 6 bit/s/Hz is experimentally demonstrated. The experiment results show that the bit error rate (BER) of the 16/4-APAM signal can be achieved less than 2.4e-2.

  13. Adaptation of spectral distribution of synchrotron radiation to X-ray depth lithography

    Plastic microstructures with extremly high aspect ratios can be fabricated by X-ray depth lithography with synchrotron radiation. In order to minimize the expenditure in terms of irradiation the spectrum of the synchrotron radiation source has to be adapted to the irradiation task. It is characterized by the height of the microstructure and the maximum admissible dose ratio permitting the resist to develop in the depth without destruction of the surface as a result of radiation damage. Expenditure in terms of irradiation is minimum if an ideal sharp cutoff filter, profiting from the maximum permissible dose ratio, filters out the long-waved portion of the spectrum without attenuating the intensity of the short-waved portion of the spectrum. By the example of a typical resist-developer system the location of the filter edge was determined at different structural heights for the Bonn synchrotron and the ELSA electron stretching facility (Bonn). To be capable of building the ideal sharp cutoff filter, the thickness of an absorber was adapted for different materials in such a way that the maximum permissible dose ratio was obtained. If a thin reflector foil is used which is hit by glazing radiation, the expenditure in terms of irradiation can be reduced because of the steeper filter characteristic of resists with small maximum dose ratios. The short-waved transmitted beam is used for irradiation, with the filter edge set by the angle between the foil and the beam. The technical feasibility of a reflection filter was demonstrated on the model of a reflector foil consisting of 30 nm titanium on 7.5 μm polyimide substrate by transmission measurements performed at different angles. (orig./HP)

  14. Carotid Artery Doppler Assessment In Patients Accussed Of Strokes

    H. Mazaher

    2005-08-01

    Full Text Available Carotid Doppler ultrasound assessment mostly indicated in patients accussed of TIAs or in younger patients with nonpersistant neurologic deficits. This assessment should be consisted of gray scale sonography, color Doppler Sonography, spectral Doppler sonography and power Doppler sonography. By gray scale sonography atherosclerotic plaques assessed from the point of Homogenousity, degree of echogenicity, surface regularity, calcification, length, Thichkness and sites of involvement. In color Doppler sonography hypoechoic Plaques which could not be identified in gray scale sonogarphy, arterial tortusity, Better and faster detection of Dis-turbed flow for flow spectrum analysis are assessed. Flow spectrum analysis and degree of stenosis in carotid arteries are assessed by Spectral Doppler sonography. Finally the main indication of carotid power Doppler sonography is differentiation Of high grade stenosis from occlusion.

  15. Doppler tracking

    Thomas, Christopher Jacob

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

  16. Doppler Imaging of Ap Stars

    Kuschnig, R.

    1998-01-01

    Doppler imaging, a technique which inverts spectral line profile variations of an Ap star into a two-dimensional abundance maps, provides new observational constraints on diffusion mechanism in the presence of a global magnetic field. A programme is presented here with the aim to obtain abundance distributions of at least five elements on each star, in order to study how different diffusion processes act under influence of a stellar magnetic field. The importance of this multi-element approac...

  17. A Rayleigh Doppler frequency estimator derived from maximum likelihood theory

    Hansen, Henrik; Affes, Sofiéne; Mermelstein, Paul

    1999-01-01

    Reliable estimates of Rayleigh Doppler frequency are useful for the optimization of adaptive multiple access wireless receivers. The adaptation parameters of such receivers are sensitive to the amount of Doppler and automatic reconfiguration to the speed of terminal movement can optimize cell capacities in low and high speed situations. We derive a Doppler frequency estimator using the maximum likelihood method and Jakes model (1974) of a Rayleigh fading channel. This estimator requires an FF...

  18. LOFAR Sonobuoy Signal Processing Based on Adaptive Line Enhancer and Doppler-CPA Positioning%基于自适应线谱增强的LOFAR浮标信号处理及Doppler-CPA定位方法

    桑龙; 王英民; 刘小明

    2009-01-01

    LOFAR浮标是一种被动全向浮标,用于对潜搜索的初始阶段.常规的LOFAR谱图对于小信噪比和有色背景噪声处理性能下降.文中采用自适应线谱增强技术将目标辐射中的线谱成分从背景噪声中分离出来进行LOFAR谱图分析,提高LOFAR浮标的检测性能.在LOFAR分析的基础上利用目标的多普勒信息,采用Doppler-CAP方法测算目标的速度和目标与浮标的距离,初步估算出目标的航迹.仿真结果表明,新的LDFAR浮标数据处理算法检测性能更好,能够得到目标与浮标最接近点的距离.

  19. Relative seismic shaking vulnerability microzonation using an adaptation of the Nakamura Horizontal to Vertical Spectral Ratio Method

    Michael L Turnbull

    2008-11-01

    An alternative seismic shaking vulnerability survey method to computational intensive theoretical modelling of site response to earthquake, and time consuming test versus reference site horizontal ratio methods, is described. The methodology is suitable for small to large scale engineering investigations. Relative seismic shaking vulnerability microzonation using an adaptation of the Nakamura horizontal to vertical spectral ratio method provides many advantages over alternative methods including: low cost; rapid field phase (100 km2 can easily be covered by a single operator in 5 days); low and flexible instrumentation requirements (a single seismometer and data logger of almost any type is required); field data can be collected at any time during the day or night (the results are insensitive to ambient social noise); no basement rock reference site is required (thus eliminating trigger synchronisation between reference and multiple test site seismographs); rapid software aided analysis; insensitivity to ground-shaking resonance peaks; ability to compare results obtained from non-contiguous survey fields. The methodology is described in detail, and a practical case study is provided, including mapped results. The resulting microzonation maps indicate the relative seismic shaking vulnerability for built structures of different height categories within adjacent zones, with a resolution of approximately 1 km.

  20. Characterisation of an airblast sputtering unit - verification of numeric simulations using an adapted phase doppler droplet measuring technique; Charakterisierung eines Airblastzerstaeubers - Bestaetigung numerischer Simulationen mit einem angepassten Phasen-Doppler-Tropfenmessverfahren

    Willmann, M.

    1999-07-01

    Two-phase flows were investigated in high-pressure conditions in order to assess the influence of pressure and temperature on spray jet dispersion in so-called airblast sputtering units, whose function is described. The project was to contribute to improved characterisation and better understanding of spray jets. New methods of measurement and calculation were employed that provide more comprehensive and accurate data on two-phase flows. [German] In der vorliegenden Arbeit sollen Zweiphasenstroemungen unter Hochdruckbedingungen untersucht werden, um den Einfluss von Druck und Temperatur auf die Spruehstrahl-Ausbreitung unter Verwendung von sogenannten Airblast-Zerstaeubern aufzuzeigen. Diese Zerstaeuberbauart wird derzeit typischerweise in Gasturbinen eingesetzt, ihre Funktionsweise wird in einem Kapitel der Arbeit dargestellt. Mit der vorliegenden Arbeit wird ein wesentlicher Beitrag zur verbesserten Charakterisierung und zum erweiterten Verstaendnis von Spruehstrahlen, insbesondere unter Einsatz von Airblast-Zerstaeubern geschaffen. Dabei werden sowohl im messtechnischen Bereich wie auch auf numerischer Seite neue Methoden vorgestellt, die eine wesentlich umfassendere und genauere Darstellung von Zweiphasenstroemungen erlauben. Der Einsatz dieser erweiterten Methoden an der Stroemung eines Modellairblastzerstaeubers zeigt wichtige Effekte bei der Tropfenausbreitung und -verdunstung auf. Die Arbeit ist dabei in drei Teilbereiche gegliedert. In einem messtechnisch ausgerichteten Teil werden die neuen, erweiterten Ansaetze zur Auslegung des Phasen-Doppler Verfahrens vorgestellt und damit die Grundlagen zur experimentellen Charakterisierung eines Spruehstrahls geschaffen. In zweiten Teil erfolgt die Darstellung der verwendeten numerischen Methoden. Im dritten Teil werden schliesslich die Resultate experimenteller wie numerischer Untersuchungen parallel eingesetzt, um die physikalischen Phaenomene im Spruehstrahl eines Airblastzerstaeubers darzustellen und damit die

  1. ANL Doppler flowmeter

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

    1985-10-01

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

  2. High resolution adaptive optics imaging complements standard spectral domain optical coherent tomography in retinal diseases with micro-structural details: a case series

    Gibran Syed Khurshid; Sasha Strul; Adam Boretsky; Massoud Motamedi; Praveena Gupta

    2016-01-01

    Purpose: To evaluate if high resolution adaptive optics confocal scanning laser ophthalmoscopy (AO-SLO) can be used as an adjunct complementary diagnostic tool to spectral domain optical coherent tomography (SD-OCT) in characterizing three macular diseases: rod-cone dystrophy, acute retinal pigment epitheliitis (Krill’s disease), and occult macular dystrophy. Methods: As part of a complete clinical examination, each patient was subjected to color fundus pictures, multimodal imaging scans with...

  3. Doppler string phantom for assessment of clinical doppler ultrasound velocity measurement

    Yi Zhang; Ted Lynch; Hangiandreou, Nicholas J.

    2014-01-01

    Purpose: The Doppler string phantom provides accurate velocity of the string motion; it can be used to calibrate Doppler ultrasound (US) velocity measurements and to evaluate variations due to intrinsic spectral broadening. We developed a semi‐automated method to estimate the mode velocity (Vmode) and peak velocity (Vmax) based on duplex US images from a string phantom, and use them to assess clinical Doppler US velocity measurement.Methods: Steady motion of a rubber O‐ring (20 – 110 cm/s) in...

  4. Doppler spectral characteristics of infrainguinal vein bypasses

    Nielsen, Tina G; von Jessen, F; Sillesen, H; Schroeder, T V

    1993-01-01

    arteriovenous fistulas the initially antegrade diastolic velocity was replaced by a retrograde flow within 3 months, whereas a forward flow in diastole was sustained in grafts with patent fistulas. Abnormal Duplex findings in 31 patients led to angiography and revision in 13 cases. Four revised grafts failed...

  5. Adapt

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  6. Doppler string phantom for assessment of clinical doppler ultrasound velocity measurement

    Yi Zhang

    2014-03-01

    Full Text Available Purpose: The Doppler string phantom provides accurate velocity of the string motion; it can be used to calibrate Doppler ultrasound (US velocity measurements and to evaluate variations due to intrinsic spectral broadening. We developed a semi‐automated method to estimate the mode velocity (Vmode and peak velocity (Vmax based on duplex US images from a string phantom, and use them to assess clinical Doppler US velocity measurement.Methods: Steady motion of a rubber O‐ring (20 – 110 cm/s in a CIRS Doppler String phantom (Model 043 was studied using GE LOGIQ E9 system with a 9L probe. 5 s of Doppler spectral data was averaged to generate a mean spectral profile. It was fitted by a Gaussian function and Vmode was defined as the velocity of the Gaussian peak, while Vmax is defined as the velocity at which the spectral profile falls to within 1 SD of the background. Vmode and Vmax were evaluated against the prescribed motor velocity. Repeatability and variation to scanning parameters were analyzed and reported in % range, i.e. (max – min / mean.Results: Vmode and Vmax had good repeatability over six days (6.0% for Vmode, 2.9% for Vmax. Gain, compression, scale, sample volume (SV depth and length, frequency and beam steering all had minimal impact on Vmode and Vmax (variations ≤ 4.4%. Doppler angle θ had minimal effect on Vmode (2.2% but a strong effect on Vmax (26% increase as θ increased from 10° to 60°. Vmode was linearly correlated with but overestimated the motor velocity (Pearson’s r = 1.05, R2 = 1.Conclusion: This study developed a simple yet robust Vmode and Vmax estimation method. Combined with a string phantom, these velocity estimators are shown to be a useful tool to evaluate clinical Doppler US system performance. For the tested system, only Doppler angle has an appreciable impact on Vmax estimation.--------------------------------------------Cite this article as: Zhang Y, Lynch T, Hangiandreou NJ. Doppler string phantom

  7. Acousto-optical adaptive correction of a chirped laser pulse spectral profile in a Nd-phosphate glass regenerative amplifier

    We present results of experimental research carried out with the help of an acousto-optical light dispersive delay line (LDDL) on spectral correction of chirped laser pulses in a Nd-doped phosphate glass regenerative amplifier (RA) characterized by high gain (G ≈ 4 × 107). The spectral resolution of the LDDL was equal to 1.1 cm−1 at a diffraction efficiency greater than 80%. The use of the LDDL made it possible to implement operating conditions of the RA under which the duration of the output chirped pulse did not shorten in comparison with the duration of the input one, which meant that the width of the spectral emission could be preserved. (letter)

  8. Clinical Doppler ultrasound

    The authors begin with the basics: how Doppler signals are formed, reflected, and refracted - and how those facts apply to clinical practice; anatomy (blood and blood flow), the Doppler equation (explained from a radiologic, rather than a mathematical, perspective); and approaches to Doppler signal production. The available methods of signal processing - including audio, multifilter analysis, zero-crossing detection, autocorrelation, and the Fast Fourier Transform, as well as more sophisticated techniques of duplex and color flow imaging - are covered with an eye to helping the ultrasonographer obtain the most reliable and artifact-free information from every Doppler reading

  9. Studies of Thermally Unstable Accretion Disks around Black Holes with Adaptive Pseudo-Spectral Domain Decomposition Method I. Limit-Cycle Behavior in the Case of Moderate Viscosity

    Li, Shuang-Liang; Lu, Ju-Fu

    2007-01-01

    We present a numerical method for spatially 1.5-dimensional and time-dependent studies of accretion disks around black holes, that is originated from a combination of the standard pseudo-spectral method and the adaptive domain decomposition method existing in the literature, but with a number of improvements in both the numerical and physical senses. In particular, we introduce a new treatment for the connection at the interfaces of decomposed subdomains, construct an adaptive function for the mapping between the Chebyshev-Gauss-Lobatto collocation points and the physical collocation points in each subdomain, and modify the over-simplified 1-dimensional basic equations of accretion flows to account for the effects of viscous stresses in both the azimuthal and radial directions. Our method is verified by reproducing the best results obtained previously by Szuszkiewicz & Miller on the limit-cycle behavior of thermally unstable accretion disks with moderate viscosity. A new finding is that, according to our ...

  10. Differential doppler heterodyning technique

    Lading, Lars

    1971-01-01

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

  11. Doppler angle correction in the measurement of intrarenal parameters

    Mennitt K

    2011-03-01

    Full Text Available Jing Gao¹, Keith Hentel¹, Qiang Zhu², Teng Ma², George Shih¹, Kevin Mennitt¹, Robert Min¹¹Department of Radiology, New York Presbyterian Hospital, Weill Cornell Medical College, NY, USA; ²Division of Diagnostic Ultrasound, Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, ChinaBackground: The aim of this study was to assess differences in intrarenal artery Doppler parameters measured without and with Doppler angle correction.Methods: We retrospectively reviewed color duplex sonography in 30 normally functioning kidneys (20 native kidneys in 10 subjects and 10 transplanted kidneys in 10 subjects performed between January 26, 2010 and July 26, 2010. There were 10 age-matched men and10 age-matched women (mean 39.8 ± 12.2, range 21–60 years in this study. Depending on whether the Doppler angle was corrected in the spectral Doppler measurement, Doppler parameters including peak systolic velocity (PSV, end-diastolic velocity (EDV, and resistive index (RI measured at the interlobar artery of the kidney were divided into two groups, ie, initial Doppler parameters measured without Doppler angle correction (Group 1 and remeasured Doppler parameters with Doppler angle correction (Group 2. Values for PSV, EDV, and RI measured without Doppler angle correction were compared with those measured with Doppler angle correction, and were analyzed statistically with a paired-samples t-test.Results: There were statistical differences in PSV and EDV at the interlobar artery in the upper, mid, and lower poles of the kidney between Group 1 and Group 2 (all P < 0.001. PSV and EDV in Group 1 were significantly lower than in Group 2. RI in Group 1 was the same as that in Group 2 in the upper, mid, and lower poles of the kidneys.Conclusion: Doppler angle correction plays an important role in the accurate measurement of intrarenal blood flow velocity. The true flow velocity converted from the maximum Doppler velocity shift

  12. High resolution adaptive optics imaging complements standard spectral domain optical coherent tomography in retinal diseases with micro-structural details: a case series

    Gibran Syed Khurshid

    2016-01-01

    Full Text Available Purpose: To evaluate if high resolution adaptive optics confocal scanning laser ophthalmoscopy (AO-SLO can be used as an adjunct complementary diagnostic tool to spectral domain optical coherent tomography (SD-OCT in characterizing three macular diseases: rod-cone dystrophy, acute retinal pigment epitheliitis (Krill’s disease, and occult macular dystrophy. Methods: As part of a complete clinical examination, each patient was subjected to color fundus pictures, multimodal imaging scans with Heidelberg SpectralisTM and high resolution retinal images with a custom built adaptive optics scanning laser ophthalmolscope (AO-SLO. The registered AO-SLO images were averaged to improve the signal to noise ratio and used to generate larger photoreceptor mosaics. Results: AO-SLO mosaics for all three conditions showed distinct, characteristic disruptions of the photoreceptors in areas that corresponded to the abnormalities observed on fundus photography and SD-OCT scans. Conclusions: AO-SLO defined fine structural changes associated with retinal pathology at the photoreceptor level that could not be achieved using standard diagnostic methods. A combination of adaptive optics scanning laser ophthalmoscopy (AO-SLO and SD-OCT provided views of the retina with enhanced lateral and axial resolution. High-resolution, ultra-structural details of the retina may provide additional insights into the disease etiology, progression and management of patients with vision threatening macular diseases.

  13. Colour Doppler ultrasound of the penis

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

    2003-07-01

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

  14. Colour Doppler ultrasound of the penis

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

  15. Blazar sequence - an artefact of Doppler boosting

    Nieppola, E.; Valtaoja, E.; Tornikoski, M.; Hovatta, T.; Kotiranta, M.

    2008-01-01

    The blazar sequence is a scenario in which the bolometric luminosity of the blazar governs the appearance of its spectral energy distribution. The most prominent result is the significant negative correlation between the synchrotron peak frequencies and the synchrotron peak luminosities of the blazar population. Observational studies of the blazar sequence have, in general, neglected the effect of Doppler boosting. We study the dependence of both the synchrotron peak frequency and luminosity ...

  16. Duplex Doppler ultrasound study of the temporomandibular joint

    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

  17. Ultrasonic colour Doppler imaging

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

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue...... weaknesses, perhaps the greatest being that in conventional systems, the velocities measured and thus displayed are the components of the flow velocity directly towards or away from the transducer, while ideally the method would give information about the magnitude and direction of the three-dimensional flow...... vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new...

  18. Cosmology with Doppler Lensing

    Bacon, David; Andrianomena, Sambatra; Clarkson, Chris; Bolejko, C.; Maartens, Roy

    2014-01-01

    Doppler lensing is the apparent change in object size and magnitude due to peculiar velocities. Objects falling into an overdensity appear larger on its near side, and smaller on its far side, than typical objects at the same redshifts. This effect dominates over the usual gravitational lensing magnification at low redshift. Doppler lensing is a promising new probe of cosmology, and we explore in detail how to utilize the effect with forthcoming surveys. We present cosmological simulations of...

  19. Rotational Doppler Effect

    Halder, Amit

    2002-01-01

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

  20. Simulation of underresolved turbulent flows by adaptive filtering using the high order discontinuous Galerkin spectral element method

    Flad, David; Beck, Andrea; Munz, Claus-Dieter

    2016-05-01

    Scale-resolving simulations of turbulent flows in complex domains demand accurate and efficient numerical schemes, as well as geometrical flexibility. For underresolved situations, the avoidance of aliasing errors is a strong demand for stability. For continuous and discontinuous Galerkin schemes, an effective way to prevent aliasing errors is to increase the quadrature precision of the projection operator to account for the non-linearity of the operands (polynomial dealiasing, overintegration). But this increases the computational costs extensively. In this work, we present a novel spatially and temporally adaptive dealiasing strategy by projection filtering. We show this to be more efficient for underresolved turbulence than the classical overintegration strategy. For this novel approach, we discuss the implementation strategy and the indicator details, show its accuracy and efficiency for a decaying homogeneous isotropic turbulence and the transitional Taylor-Green vortex and compare it to the original overintegration approach and a state of the art variational multi-scale eddy viscosity formulation.

  1. Calculation of the two-body scattering K-matrix in configuration space by an adaptive spectral method

    A spectral integral method (IEM) for solving the two-body, one-variable Lippmann-Schwinger equation for the wavefunction in configuration space is generalized to the case of the two-variable scattering K-matrix. The main difficulty is that in this case the driving term of the integral equation is discontinuous. It is found that the desirable features of the IEM, such as the economy of mesh points for a given required accuracy, are carried over also to this case even though the result is also discontinuous. The main innovation is a judicious choice of the partitions in coordinate space, plus a new recursion relation forward and backward to the point of discontinuity. For a simple exponential potential an accuracy of 7 significant figures is achieved for the K-matrix, with the number N of Chebyshev support points in each partition equal to 17. For a potential with a large repulsive core, such as the potential between two He atoms, an accuracy of 7 significant figures requires that N is increased to 65 support points per partition

  2. Preoperative evaluation of ovarian masses with color Doppler and its correlation with pathological finding

    Isha Khurana

    2016-07-01

    Conclusions: Color Doppler is a good non-invasive modality to differentiate benign from malignant lesions. Vascularity is most sensitive and RI is most specific. Thus, color Doppler and spectral Doppler tremendously increased the reliability in diagnosing a malignant ovarian tumor. Color Doppler served as an important tool to rule out malignancy in solid tumors if they failed to show any intra-tumoral vascularity. B-Mode USG in combination with color Doppler and spectral Doppler is proposed as the first and foremost diagnostic modality in patients with ovarian tumor, so as to establish the definite diagnosis of malignancy early in the course of the disease. [Int J Reprod Contracept Obstet Gynecol 2016; 5(7.000: 2084-2092

  3. Doppler cooling a microsphere

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The scattering force is not limited by saturation, but can be controlled by the incident power. Cooling times on the order of seconds are calculated for a 20 micron diameter silica microsphere trapped within optical tweezers, with a Doppler temperature limit in the microKelvin regime.

  4. Doppler-suuntima-algoritmi

    Rekis, Matti

    2014-01-01

    Doppler-ilmiö aiheuttaa havaitsijan ja signaalilähteen välisen suhteellisen liikkeen seurauksena taajuusvääristymää lähteen alkuperäisestä signaalista. Tämä mm. doppler-siirtymäksi kutsuttu vääristymä voidaan havaita signaalilähteen taajuudessa, aallonpituudessa ja vaiheessa. Doppler-siirtymän suuruuteen ja suuntaan vaikuttaa se, kasvaako vai pieneneekö havaitsijan ja lähteen välinen etäisyys sekä niiden välinen suhteellinen nopeus. Tätä ilmiötä voidaan hyödyntää mm. radiolähettimen paikantam...

  5. Pulse Doppler radar

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  6. Doppler Cooling a Microsphere

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The...

  7. Polarimetric Doppler Weather Radar

    Bringi, V. N.; Chandrasekar, V.

    2001-10-01

    This work provides a detailed introduction to the principles of Doppler and polarimetric radar, focusing in particular on their use in the analysis of weather systems. The authors first discuss underlying topics such as electromagnetic scattering, polarization, and wave propagation. They then detail the engineering aspects of pulsed Doppler polarimetric radar, before examining key applications in meteorology and remote sensing. The book is aimed at graduate students of electrical engineering and atmospheric science as well as practitioners involved in the applications of polarimetric radar.

  8. Doppler blood flow indicator

    Byrtus, David

    2014-01-01

    This bachelor´s thesis deals with basis of ultra-acoustics. The project presents basic information about Doppler effect. It describes the methods of processing and analyzing of velocity and direction of blood at doppler’s systems with modulated and unmodulated carrier wave. The project presents the system design of non-directional doppler indicator with unmodulated carrier wave for 8 MHz frequency, generating intensity of ultrasound 100 mW/cm2 and diameter D-shaped transmitting transducer 8 m...

  9. Doppler Signatures of the Atmospheric Circulation on Hot Jupiters

    Showman, Adam P; Lewis, Nikole K; 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 blue- 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...

  10. Doppler-musical instrument

    We propose a possible ultra-high energy resolution backscattering spectrometer optimized to spallation neutron source. A combination of multi monochromator crystal and Doppler drive provides considerable neutron flux, together with the reasonable energy range -30 < E < 30 μeV, even when the ultra-high energy resolution of ΔE∼0.03 μeV is attained. (author)

  11. Superharmonic microbubble Doppler effect in ultrasound therapy

    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

  12. Equivariant Lorentzian Spectral Triples

    Paschke, Mario; Sitarz, Andrzej

    2006-01-01

    We present examples of equivariant noncommutative Lorentzian spectral geometries. The equivariance with respect to a compact isometry group (or quantum group) allows to construct the algebraic data of a version of spectral triple geometry adapted to the situation of an indefinite metric. The spectrum of the equivariant Dirac operator is calculated.

  13. Sub-Doppler resolution with double coherently driving fields

    Dong, P; Hai, T S; Gao, J Y; Dong, Po; Hai, Tang Sing; Gao, Jin-Yue

    2000-01-01

    We propose a four-level model where sub-Doppler resolution as well as enhanced absorption of a weak probe field are realized by using two coherently driving fields. We show that spectral resolution can be improved by modifying the coherent fields intensity and frequencies.

  14. HF Doppler observations

    Kikuchi, T.; Sugiuchi, H.; Ishimine, T.; Maeno, H.; Honma, S.

    1986-12-01

    This paper reports the solar flare and geomagnetic storm effects on the frequency of JJY signals received at Okinawa (f = 15 MHz) and Kokubunji (f = 5 and 8 MHz) during the period of June-September 1982. The increase in the electron density due to solar flares is deduced from the Doppler frequency deviation of 1 Hz as 2 x 10/sup 15/ electrons/m/sub 2/ below the reflection height. The result is in good agreement with the observation of the total electron content by the Faraday rotation measurements. On July 13, 1982, an abrupt increase of 0.8 Hz in frequency followed by a decrease of 0.6 Hz was observed in association with the huge storm sudden commencement. This fact indicates a successive transmission of westward electric field of 1.5 mV/m and eastward electric field of 1.1 mV/m from the outer magnetosphere to the low latitude ionosphere. It is shown that the decreases in Doppler frequency were associated with geomagnetic bays. The strength of the electric field (1.8 mV/m) derived from the Doppler frequency deviation is 20% of that of the electric field which is required to produce ionospheric electric currents responsible for the geomagnetic field variation on the ground. The large amplitude Doppler frequency oscillations of period of 1-1.5 h were observed at Kokubunji and Okinawa with a delay time of 20-25 min during the geomagnetic storm on September 6, 1982. It is suggested that the large-scale TID (Travelling Ionospheric Disturbance) with a phase velocity of 600 m/s and a wavelength of 2000 km is produced at high latitudes and is propagated to low latitudes.

  15. Quantitative Laser Doppler Flowmetry

    Fredriksson, Ingemar

    2009-01-01

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

  16. Holographic laser Doppler ophthalmoscopy

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

    2010-01-01

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

  17. Laser double Doppler flowmeter

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

    2014-05-01

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

  18. Doppler evaluation of valvular regurgitation

    The many examples described in this chapter show that there are several major points to keep in mind when examining patients for the presence of valvular insufficiency. One practical point not previously emphasized is that the audible output may be more sensitive than the spectral display. It is not infrequent that a given lesion is heard by audio but cannot be adequately recorded on the spectral hard copy. Interpretation in these cases is often difficult and, in our experience, usually involves a tradeoff. Accepting audio evidence of a regurgitant lesion without hard-copy confirmation increases the sensitivity of the procedure but will also result in an increased number of false-positive diagnoses. Currently, we require hard-copy confirmation before we will report definite evidence of valvular regurgitation. Second, it is important for the operator to take time to search for small regurgitant jets. When searching for insufficiency by pulsed wave with an instrument that has a variable sample volume size, one should not routinely begin the examination with a sample volume size that is as large as possible. Although this may seem desirable for locating small jets, the operator must remember that this process will frequently result in a loss of system sensitivity. Third, the opertor should expect regurgitant jets to exceed a velocity of 1.5m/sec and result in aliasing when in pulsed wave mode. This is certainly true in most adults, since regurgitant lesions are located far enough away from the transducer to cause the Nyquist limit to be exceeded. Thus, in almost every instance, pulsed Doppler operators should expect aliasing of regurgitant lesion. Fourth, particularly beginners should be prepared to switch back and forth between pulsed and continuous wave modes

  19. Spectral polarimetric radar clutter suppression to enhance atmospheric echoes

    Unal, C.M.H.

    2009-01-01

    The clutter present in the Doppler spectra of atmospheric targets can be removed by using polarimetry. The purpose is to suppress the Doppler velocity bins where spectral polarimetric parameters have atypical values. This procedure largely improves profiles of moments and polarimetric parameters of

  20. Laser doppler perfusion imaging

    Waardell, K.

    1992-01-01

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

  1. Laser doppler perfusion imaging

    Waardell, K.

    1992-11-01

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

  2. Laser doppler perfusion imaging

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

  3. Rotational Doppler Effect: A Probe for Molecular Orbitals Anisotropy.

    Miao, Quan; Travnikova, Oksana; Gel'mukhanov, Faris; Kimberg, Victor; Sun, Yu-Ping; Thomas, T Darrah; Nicolas, Christophe; Patanen, Minna; Miron, Catalin

    2015-05-01

    The vibrationally resolved X-ray photoelectron spectra of X2Σg+(3σg−1) and B2Σu+(2σu−1) states of N2+ were recorded for different photon energies and orientations of the polarization vector. Clear dependencies of the spectral line widths on the X-ray polarization as well as on the symmetry of the final electronic states are observed. Contrary to the translational Doppler, the rotational Doppler broadening is sensitive to the photoelectron emission anisotropy. On the basis of theoretical modeling, we suggest that the different rotational Doppler broadenings observed for gerade and ungerade final states result from a Young's double-slit interference phenomenon. PMID:26263315

  4. Doppler Beats or Interference Fringes?

    Kelly, Paul S.

    1979-01-01

    Discusses the following: another version of Doppler beats; alternate proof of spin-1 sin-1/2 problems; some mechanisms related to Dirac's strings; Doppler redshift in oblique approach of source and observer; undergraduate experiment on noise thermometry; use of the time evolution operator; resolution of an entropy maximization controversy;…

  5. DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS

    Showman, Adam P.; Lewis, Nikole K. [Department of Planetary Sciences and Lunar and Planetary Laboratory, The University of Arizona, 1629 University Boulevard, Tucson, AZ 85721 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Shabram, Megan, E-mail: showman@lpl.arizona.edu [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States)

    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.

  6. Gold nanorods as a contrast agent for Doppler optical coherence tomography.

    Bo Wang

    Full Text Available PURPOSE: To investigate gold nanorods (GNRs as a contrast agent to enhance Doppler optical coherence tomography (OCT imaging of the intrascleral aqueous humor outflow. METHODS: A serial dilution of GNRs was scanned with a spectral-domain OCT device (Bioptigen, Durham, NC to visualize Doppler signal. Doppler measurements using GNRs were validated using a controlled flow system. To demonstrate an application of GNR enhanced Doppler, porcine eyes were perfused at constant pressure with mock aqueous alone or 1.0×10(12 GNR/mL mixed with mock aqueous. Twelve Doppler and volumetric SD-OCT scans were obtained from the limbus in a radial fashion incremented by 30°, forming a circular scan pattern. Volumetric flow was computed by integrating flow inside non-connected vessels throughout all 12 scans around the limbus. RESULTS: At the GNR concentration of 0.7×10(12 GNRs/mL, Doppler signal was present through the entire depth of the testing tube without substantial attenuation. A well-defined laminar flow profile was observed for Doppler images of GNRs flowing through the glass capillary tube. The Doppler OCT measured flow profile was not statistically different from the expected flow profile based upon an autoregressive moving average model, with an error of -0.025 to 0.037 mm/s (p = 0.6435. Cross-sectional slices demonstrated the ability to view anterior chamber outflow ex-vivo using GNR-enhanced Doppler OCT. Doppler volumetric flow measurements were comparable to flow recorded by the perfusion system. CONCLUSIONS: GNRs created a measureable Doppler signal within otherwise silent flow fields in OCT Doppler scans. Practical application of this technique was confirmed in a constant pressure ex-vivo aqueous humor outflow model in porcine eyes.

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

    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.

  8. Ship motion estimation from polarized Doppler spectra from ship wakes on two-dimensional sea surfaces

    Jiang, Wang-Qiang; Zhang, Min; Nie, Ding; Sun, Rong-Qing

    2016-07-01

    The main purpose of this paper is to investigate the Doppler spectra from ship wakes on two-dimensional sea surfaces and further estimate the ship motion characteristics. The analysis of the ship wakes is helpful to detect the existence of ships on sea surface. And it will be an alternative method when the radar cross-section values are not competent to identify the ship target. In the study, Doppler spectra for different polarizations are compared with and without ship's wakes based on the second-order small slope approximation method. As expected, there appears the second spectral peak when ship's wake is considered. Moreover, the ship velocities, wind speed, and direction are also analyzed. As the results shown, there is a good linearity relation between the position of the second Doppler spectral peak and the ship velocity. Therefore, it is feasible to detect ship according the Doppler spectra.

  9. Triplex Doppler evaluation of the testes in dogs of different sizes

    Mírley B. Souza

    2014-11-01

    Full Text Available This study aimed to assess whether there are differences in Doppler velocimetry parameters between different sizes. Twenty dogs were equally divided into small and large groups used in this study. The dogs were evaluated using Triplex ultrasound. Testicular artery was located by Colour Doppler in the spermatic cord, marginal to the testes and intratesticular segments and then, spectral Doppler were used to calculate: peak systolic velocity (PSV, end diastolic velocity (EDV, resistance index (RI and pulsatility index (PI. The mean testicular volume in the left side was significantly higher than the right side, in both groups. Doppler examination showed higher velocities (EDV at spermatic cord in large dogs; marginal to the testes was observed higher velocities in small dogs; intratesticular region no differences were observed (P < 0.05 and within the groups differences between segments of the artery were also observed for each parameter. The results showed that there are differences in Doppler velocimetry parameters between different sizes.

  10. Caroli's disease: hepatic arterial color doppler signals in the communicating dilated bile ducts

    Lee, Moon Gyu; Han, Boo Kyung; Baek, Seong Yon; Cho, Kyoung Sik; Auh, Yong Ho; Kim, Myung Hwan; Yu, Eun Sil [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    1992-01-15

    Three siblings with congenital dilatation of the intrahepatic bile ducts (Caroli's disease) are presented. Bile duct pathology was associated with congenital hepatic fibrosis and polycystic renal disease in all three patients. On color Doppler imaging (CD imaging), multiple small color Doppler signals were observed in or near the vascular radicles within the dilated bile ducts, besides other well-known sonographic findings such as bile duct dilatation, biliary calculi. Doppler frequency spectral analysis confirmed all these color Doppler signals as arterial origin in all patients, showing pulsatile wave pattern. Although portal venous radicles are well known in conventional sonograms or computed tomography(CT), continuous wave patterns were not detected in all patients. In addition to previously reported sonographic findings about Caroli's disease, color Doppler signals showing arterial wave pattern in or around the portal venous radicles within dilated ducts are another helpful diagnostic criteria and those findings are easily depicted on routine sonograms with color mapping.

  11. Caroli's disease: hepatic arterial color doppler signals in the communicating dilated bile ducts

    Three siblings with congenital dilatation of the intrahepatic bile ducts (Caroli's disease) are presented. Bile duct pathology was associated with congenital hepatic fibrosis and polycystic renal disease in all three patients. On color Doppler imaging (CD imaging), multiple small color Doppler signals were observed in or near the vascular radicles within the dilated bile ducts, besides other well-known sonographic findings such as bile duct dilatation, biliary calculi. Doppler frequency spectral analysis confirmed all these color Doppler signals as arterial origin in all patients, showing pulsatile wave pattern. Although portal venous radicles are well known in conventional sonograms or computed tomography(CT), continuous wave patterns were not detected in all patients. In addition to previously reported sonographic findings about Caroli's disease, color Doppler signals showing arterial wave pattern in or around the portal venous radicles within dilated ducts are another helpful diagnostic criteria and those findings are easily depicted on routine sonograms with color mapping

  12. Doppler selection of HF radiosignals on long paths

    Zalizovskii, A. V.; Galushko, V. G.; Kashcheev, A. S.; Koloskov, A. V.; Yampolski, Yu. M.; Egorov, I. B.; Popov, A. V.

    2007-10-01

    The long-term registration of the Doppler spectra of HF radiosignals has been performed on the Moscow-Akademik Vernadsky Ukrainian Antarctic station path. It has been revealed that the spectra are split when the solar terminator crosses direct and return radio lines. The spectral and energy characteristics of direct and return signals have been calculated within the scope of the asymptotic theory of long-range propagation of decametric radiowaves.

  13. Effects of treatment with etanercept (Enbrel, TNRF:Fc) on rheumatoid arthritis evaluated by Doppler ultrasonography

    Terslev, L; Torp-Pedersen, S; Qvistgaard, E; Kristoffersen, H; Rogind, H; Danneskiold-Samso..., B; Bliddal, H

    2003-01-01

    Methods: Eleven patients from the European multicentre trial of the efficacy and safety of etanercept were included in this study when transferred into the open label, long term safety, and efficacy study. Before a scheduled dosage increase to 50 mg/week they were examined clinically, serologically, and by ultrasonography using the colour Doppler pixels and the spectral Doppler resistance index (RI) as indicators of inflammation. The patients were re-examined at two weeks and at one year foll...

  14. Dual-Doppler Feasibility Study

    Huddleston, Lisa L.

    2012-01-01

    When two or more Doppler weather radar systems are monitoring the same region, the Doppler velocities can be combined to form a three-dimensional (3-D) wind vector field thus providing for a more intuitive analysis of the wind field. A real-time display of the 3-D winds can assist forecasters in predicting the onset of convection and severe weather. The data can also be used to initialize local numerical weather prediction models. Two operational Doppler Radar systems are in the vicinity of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS); these systems are operated by the 45th Space Wing (45 SW) and the National Weather Service Melbourne, Fla. (NWS MLB). Dual-Doppler applications were considered by the 45 SW in choosing the site for the new radar. Accordingly, the 45th Weather Squadron (45 WS), NWS MLB and the National Aeronautics and Space Administration tasked the Applied Meteorology Unit (AMU) to investigate the feasibility of establishing dual-Doppler capability using the two existing systems. This study investigated technical, hardware, and software requirements necessary to enable the establishment of a dual-Doppler capability. Review of the available literature pertaining to the dual-Doppler technique and consultation with experts revealed that the physical locations and resulting beam crossing angles of the 45 SW and NWS MLB radars make them ideally suited for a dual-Doppler capability. The dual-Doppler equations were derived to facilitate complete understanding of dual-Doppler synthesis; to determine the technical information requirements; and to determine the components of wind velocity from the equation of continuity and radial velocity data collected by the two Doppler radars. Analysis confirmed the suitability of the existing systems to provide the desired capability. In addition, it is possible that both 45 SW radar data and Terminal Doppler Weather Radar data from Orlando International Airport could be used to alleviate any

  15. High Resolution Doppler Lidar

    1996-01-01

    This Grant supported the development of an incoherent lidar system to measure winds and aerosols in the lower atmosphere. During this period the following activities occurred: (1) an active feedback system was developed to improve the laser frequency stability; (2) a detailed forward model of the instrument was developed to take into account many subtle effects, such as detector non-linearity; (3) a non-linear least squares inversion method was developed to recover the Doppler shift and aerosol backscatter without requiring assumptions about the molecular component of the signal; (4) a study was done of the effects of systematic errors due to multiple etalon misalignment. It was discovered that even for small offsets and high aerosol loadings, the wind determination can be biased by as much as 1 m/s. The forward model and inversion process were modified to account for this effect; and (5) the lidar measurements were validated using rawinsonde balloon measurements. The measurements were found to be in agreement within 1-2 m/s.

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

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

    2016-03-01

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

  17. The lineshape problem in Doppler-width thermometry

    Domenica De Vizia, Maria; Moretti, Luigi; Castrillo, Antonio; Fasci, Eugenio; Gianfrani, Livio

    2011-09-01

    Typically eliminated in any experiment of time and frequency metrology, the Doppler broadening effect can be regarded as a gift of nature for the purpose of measuring the thermodynamic temperature of a gaseous sample. Nevertheless, Doppler-width retrieval from highly-accurate absorption spectra is surely not an easy task as it requires an adequate knowledge of the lineshape function, accounting for the different mechanisms that contribute to the overall linewidth. Semiclassical theories provide several possibilities, more or less accurate in reproducing the observed profiles. Here, the influence of the choice of the lineshape model in Doppler-width thermometry is investigated in the physical situation of self-colliding ? O molecules. A large number of absorption profiles were simulated, using the uncorrelated version of the speed-dependent Galatry profile and setting different values for the gas pressure, the signal-to-noise ratio and the Dicke-narrowing parameter. Spectral analysis was performed by means of different models, in order to retrieve the zero-pressure value of the Doppler width. It turned out that precision and accuracy can be pushed to extreme levels provided that the signal-to-noise ratio is sufficiently high (namely, larger than 50,000) and that a speed-dependent lineshape model is used.

  18. Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. Both regular and high-frequency spectral components can be recovered from the data--the moire component carries additional information that increases the signal to noise for velocimetry and spectroscopy. Here we present simulations and theoretical studies of the photon limited Doppler velocity noise in an EDI. We used a model spectrum of a 1600K temperature star. For several rotational blurring velocities 0, 7.5, 15 and 25 km/s we calculated the dimensionless Doppler quality index (Q) versus wavenumber v. This is the normalized RMS of the derivative of the spectrum and is proportional to the photon-limited Doppler signal to noise ratio

  19. Planetary Doppler Imaging

    Murphy, N.; Jefferies, S.; Hart, M.; Hubbard, W. B.; Showman, A. P.; Hernandez, G.; Rudd, L.

    2014-12-01

    Determining the internal structure of the solar system's gas and ice giant planets is key to understanding their formation and evolution (Hubbard et al., 1999, 2002, Guillot 2005), and in turn the formation and evolution of the solar system. While internal structure can be constrained theoretically, measurements of internal density distributions are needed to uncover the details of the deep interior where significant ambiguities exist. To date the interiors of giant planets have been probed by measuring gravitational moments using spacecraft passing close to, or in orbit around the planet. Gravity measurements are effective in determining structure in the outer envelope of a planet, and also probing dynamics (e.g. the Cassini and Juno missions), but are less effective in probing deep structure or the presence of discrete boundaries. A promising technique for overcoming this limitation is planetary seismology (analogous to helioseismology in the solar case), postulated by Vorontsov, 1976. Using trapped pressure waves to probe giant planet interiors allows insight into the density and temperature distribution (via the sound speed) down to the planetary core, and is also sensitive to sharp boundaries, for example at the molecular to metallic hydrogen transition or at the core-envelope interface. Detecting such boundaries is not only important in understanding the overall structure of the planet, but also has implications for our understanding of the basic properties of matter at extreme pressures. Recent Doppler measurements of Jupiter by Gaulme et al (2011) claimed a promising detection of trapped oscillations, while Hedman and Nicholson (2013) have shown that trapped waves in Saturn cause detectable perturbations in Saturn's C ring. Both these papers have fueled interest in using seismology as a tool for studying the solar system's giant planets. To fully exploit planetary seismology as a tool for understanding giant planet structure, measurements need to be made

  20. Inverse Doppler Effects in Flute

    Zhao, Xiao P; Liu, Song; Shen, Fang L; Li, Lin L; Luo, Chun R

    2015-01-01

    Here we report the observation of the inverse Doppler effects in a flute. It is experimentally verified that, when there is a relative movement between the source and the observer, the inverse Doppler effect could be detected for all seven pitches of a musical scale produced by a flute. Higher tone is associated with a greater shift in frequency. The effect of the inverse frequency shift may provide new insights into why the flute, with its euphonious tone, has been popular for thousands of years in Asia and Europe.

  1. Doppler Ultrasound Doppler and their applications in maternal medicine

    In this paper the technical aspects and physical principles of Doppler ultrasound are discussed, as well as the analysis that can be made from the quantitative and qualitative data. Finally, its utility in perinatal medicine is reviewed with emphasis in the clinical implications

  2. Doppler tomography in fusion plasmas and astrophysics

    Salewski, Mirko; Heidbrink, Bill; Jacobsen, Asger Schou; Korsholm, Soren Bang; Leipold, Frank; Madsen, Jens; Moseev, Dmitry; Nielsen, Stefan Kragh; Rasmussen, Jesper; Stagner, Luke; Steeghs, Danny; Stejner, Morten; Tardini, Giovani; Weiland, Markus

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion D-alpha (FIDA) spectroscopy measurements in magnetically confined plasma, the D-alpha-photons are likewise Doppler-shifted ultimately due to gyration of the fast ions. In either case, spectra of Doppler-shifted line emission are sensitive to the velocity distribution of the emitters. Astrophysical Doppler tomography has lead to images of accretion discs of binaries revealing bright spots, spiral structures, and flow patterns. Fusion plasma Doppler tomography has lead to an image of the fast-ion velocity distribution function in the tokamak ASDEX Upgrade. This image matched numerical simulations very well. Here we discuss achievements of the Doppler tomography approach, its promise and limits, analogies and differences in astrophysical and fusion plasma Doppler tomography, and what ...

  3. Duplex and color-Doppler US for the evaluation of renovascular hypertension

    Doppler US was employed to examine 46 patients with suspected renovascular hypertension (RVI) to detect stenosis/occlusion of the renal artery. In 25 cases duplex- Doppler techique was used, in 19 color-Doppler US, and 2 patients were examined with both methods. Doppler US was always performed before angiography which was censidered as the reference gold standard. Using duplex-Doppler US, the diagnosis of renal artery stenosis was based on qualitative (spectral analysis of the waveform and absence of flow signal in cases of renal artery occlusion), andf semiquantitative parameters (resistive index). Diagnostic accuracy of duplex US- which was compared with that of angiography- was 83%, its sensitivity was 91.6%, and specificity was 85%. With color-Doppler, two additional quantitative parameters were used (peak systolic frequency shift at the stenosis and stenosis index). In this group of patients sensitivity was 70%, specificity was 100%, and accuracy 85%. The good diagnostic yeld of the method is counter-balanced by some limitations- e.g. operator dependence and long examination time (30-40 minutes, especially with duplex US). In the authors' opinion, Doppler technique can be used in the diagnosis of RVI, even though further study is necessary to exactly define diagnostic parameters, and to verify reproducibility and both inter- and intra-observer repeatibility. Technological progress may in the future reduce both difficulty and time of examination

  4. Mie-Rayleigh Doppler Wind Lidar with Two Double-edge Interferometers

    孙东松

    2002-01-01

    The Mie-Rayleigh direct detection Doppler lidar (DDDL) with two double-edge etalons is presented. Fabry-Perot (F-P) etalon is used as the spectral analyzer for Doppler measurement formthe aerosol and molecule backscattered signals. The aerosol and molecular backscattering signals are separated by a polarization isolator with less signal decrement, so this system has about same accuracy as individual Rayleigh Doppler lidar or Mie Doppler lidar system. The simulation on a proposed ground-based DDDL at 532 nm shows that the velocity error is less than 2 m/s below 8 km for a 100 m vertical resolution by Mie channel and 2m/s up to 20 km by Rayleigh channel, respectively.

  5. Theoretical model for Sub-Doppler Cooling with EIT System

    He, Peiru; Tengdin, Phoebe; Anderson, Dana; Rey, Ana Maria; Holland, Murray

    2016-05-01

    We propose a of sub-Doppler cooling mechanism that takes advantage of the unique spectral features and extreme dispersion generated by the so-called Electromagnetically Induced Transparency (EIT) effect, a destructive quantum interference phenomenon experienced by atoms with Lambda-shaped energy levels when illuminated by two light fields with appropriate frequencies. By detuning the probe lasers slightly from the ``dark resonance'', we observe that atoms can be significantly cooled down by the strong viscous force within the transparency window, while being just slightly heated by the diffusion caused by the small absorption near resonance. In contrast to polarization gradient cooling or EIT sideband cooling, no external magnetic field or external confining potential are required. Using a semi-classical method, analytical expressions, and numerical simulations, we demonstrate that the proposed EIT cooling method can lead to temperatures well below the Doppler limit. This work is supported by NSF and NIST.

  6. Anomalous Doppler effects in bulk phononic crystal

    Doppler effects in simple cubic phononic crystal are studied theoretically and numerically. In addition to observing Doppler shifts from a moving source's frequencies inside the gap, we find that Doppler shifts can be multi-order, anisotropic, and the dominant order of shift depends on the band index that the source's frequency is in.

  7. Three-dimensional power doppler imaging

    Three-dimensional (3-D) ultrasonographic imaging techniques have recently shown rapid development and their clinical application has begun to attract considerable attention. Power Doppler sonography is known to be more sensitive than color Doppler for detecting blood flow, and there is also less noise and clutter. This paper describes the basic principles and initial clinical experience of 3-D power Doppler sonography

  8. The Doppler Effect--A New Approach

    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)

  9. Reverse Doppler Effect of Sound

    Lee, Sam Hyeon; Park, Choon Mahn; Seo, Yong Mun; Wang, Zhi Guo; Kim, Chul Koo

    2009-01-01

    We report observation of reverse Doppler effect in a double negative acoustic metamaterial. The metamaterial exhibited negative phase velocity and positive group velocity. The dispersion relation is such that the wavelength corresponding to higher frequency is longer. We observed that the frequency was down-shifted for the approaching source, and up-shifted when the source receded.

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

    Dadashi, Neda; Solanki, Sami K

    2011-01-01

    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. Here we analyse combined SUMER/SoHO and EIS/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. 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 a...

  11. The spectral shift function and spectral flow

    Azamov, N. A.; Carey, A. L.; Sukochev, F. A.

    2007-01-01

    This paper extends Krein's spectral shift function theory to the setting of semifinite spectral triples. We define the spectral shift function under these hypotheses via Birman-Solomyak spectral averaging formula and show that it computes spectral flow.

  12. Azimuthal Doppler Effect in Optical Vortex Spectroscopy

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

    2015-11-01

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

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

    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.

  14. Spectral stratigraphy

    Lang, Harold R.

    1991-01-01

    A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

  15. Spectral Analysis

    Cecconi, Jaures

    2011-01-01

    G. Bottaro: Quelques resultats d'analyse spectrale pour des operateurs differentiels a coefficients constants sur des domaines non bornes.- L. Garding: Eigenfuction expansions.- C. Goulaouic: Valeurs propres de problemes aux limites irreguliers: applications.- G. Grubb: Essential spectra of elliptic systems on compact manifolds.- J.Cl. Guillot: Quelques resultats recents en Scattering.- N. Schechter: Theory of perturbations of partial differential operators.- C.H. Wilcox: Spectral analysis of the Laplacian with a discontinuous coefficient.

  16. Adaptive real-time dual-comb spectroscopy

    Ideguchi, Takuro; Guelachvili, Guy; Picqué, Nathalie; Hänsch, Theodor W

    2012-01-01

    With the advent of laser frequency combs, coherent light sources that offer equally-spaced sharp lines over a broad spectral bandwidth have become available. One decade after revolutionizing optical frequency metrology, frequency combs hold much promise for significant advances in a growing number of applications including molecular spectroscopy. Despite its intriguing potential for the measurement of molecular spectra spanning tens of nanometers within tens of microseconds at Doppler-limited resolution, the development of dual-comb spectroscopy is hindered by the extremely demanding high-bandwidth servo-control conditions of the laser combs. Here we overcome this difficulty. We experimentally demonstrate a straightforward concept of real-time dual-comb spectroscopy, which only uses free-running mode-locked lasers without any phase-lock electronics, a posteriori data-processing, or the need for expertise in frequency metrology. The resulting simplicity and versatility of our new technique of adaptive dual-com...

  17. A new adaptive method to filter terrestrial laser scanner point clouds using morphological filters and spectral information to conserve surface micro-topography

    Rodríguez-Caballero, E.; Afana, A.; Chamizo, S.; Solé-Benet, A.; Canton, Y.

    2016-07-01

    Terrestrial laser scanning (TLS), widely known as light detection and ranging (LiDAR) technology, is increasingly used to provide highly detailed digital terrain models (DTM) with millimetric precision and accuracy. In order to generate a DTM, TLS data has to be filtered from undesired spurious objects, such as vegetation, artificial structures, etc., Early filtering techniques, successfully applied to airborne laser scanning (ALS), fail when applied to TLS data, as they heavily smooth the terrain surface and do not retain their real morphology. In this article, we present a new methodology for filtering TLS data based on the geometric and radiometric properties of the scanned surfaces. This methodology was built on previous morphological filters that select the minimum point height within a sliding window as the real surface. However, contrary to those methods, which use a fixed window size, the new methodology operates under different spatial scales represented by different window sizes, and can be adapted to different types and sizes of plants. This methodology has been applied to two study areas of differing vegetation type and density. The accuracy of the final DTMs was improved by ∼30% under dense canopy plants and over ∼40% on the open spaces between plants, where other methodologies drastically underestimated the real surface heights. This resulted in more accurate representation of the soil surface and microtopography than up-to-date techniques, eventually having strong implications in hydrological and geomorphological studies.

  18. Causality and the Doppler Peaks

    Turok, Neil

    1996-01-01

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

  19. [Doppler echocardiography in endomyocardial fibrosis].

    Tello, R; Cuan, V; Abundes, A; Navarro, J; García Lara, J; Astudillo, R; Ariza, H; Cuan, M

    1994-01-01

    Twelve patients with endomyocardial fibrosis with angiographic and/or histologic corroboration were studied with Doppler echocardiography with the purpose of describing the echocardiographic features and identify the affected sites. The average age was 41 years (range 16 to 59 years), 2 men and 10 women. Three patients (25%) had isolated right ventricular involvement, one patient (8%) left ventricular, 8 patients (66%) both ventricular. Our Doppler echocardiographic findings were: right atrium enlargement (91%), right ventricle outflow dilatation (83%), paradoxical septal motion (83%), left atrial enlargement (33%), mitral and tricuspid valve prolapse (50%), pericardial effusion (41%), mitral regurgitation (75%), tricuspid regurgitation (100%), apex obliteration (50%) and a restrictive type flow pattern (50%). Doppler echocardiography is a useful method for the diagnosis of endomyocardial fibrosis, the finding of normal or small ventricles associated with apex obliteration and enlarged atria, mitral or tricuspid regurgitation and a restrictive type flow pattern are characteristics of this disease. In our population, the isolated or predominantely right ventricular involvement is the most common finding as it represented 83% of the cases. PMID:7979815

  20. A new time-domain narrowband velocity estimation technique for Doppler ultrasound flow imaging. I. Theory.

    Vaitkus, P J; Cobbold, R C

    1998-01-01

    A significant improvement in blood velocity estimation accuracy can be achieved by simultaneously processing both temporal and spatial information obtained from a sample volume. Use of the spatial information becomes especially important when the temporal resolution is limited. By using a two-dimensional sequence of spatially sampled Doppler signal "snapshots" an improved estimate of the Doppler correlation matrix can be formed. Processing Doppler data in this fashion addresses the range-velocity spread nature of the distributed red blood cell target, leading to a significant reduction in spectral speckle. Principal component spectral analysis of the "snapshot" correlation matrix is shown to lead to a new and robust Doppler mode frequency estimator. By processing only the dominant subspace of the Doppler correlation matrix, the Cramer-Rao bounds on the estimation error of target velocity is significantly reduced in comparison to traditional narrowband blood velocity estimation methods and achieves almost the same local accuracy as a wideband estimator. A time-domain solution is given for the velocity estimate using the root-MUSIC algorithm, which makes the new estimator attractive for real-time implementation. PMID:18244249

  1. The usefulness of pulsatile flow detection in measuring resistive index in renal doppler US

    To assess the usefulness of pulsatile flow detection (PFD), a newly developed function of color Doppler US, in measuring resistive index (RI) in renal Doppler US and to compare it with conventional color Doppler (CCD). Fifty-six kidneys in 31 patients were randomly selected and divided into two groups. In group A, RI was measured first with the aid of CCD, and then with PFD. In group B, data were obtained in the reverse order. The time required for each RI measurement was recorded in seconds. The quality of the Doppler spectral waveform was subjectively graded as 0, 1, or 2 and examination time and waveform quality were compared between PFD and CCD. The time required to measure RI with PFD (PFD time) was less than with CCD (CCD time) (mean 42.7 secs vs. mean 70.3 secs; p = 0.031). There was no significant difference in PFD time between group A and B, but CCD time was shorter in group B (70.3 secs vs. 24.6 secs; p = 0.0004). Spectral waveform quality was not significantly different between PFD and CCD. The time required to measure RI in kidneys can be shortened with the aid of the PFD function in color Doppler US without affecting the quality of the examination

  2. Phylloedes tumor of breast: findings at mammography, sonography and color Doppler imaging

    The phylloides tumor of the breast is rare. the purposes of this study were to find the characteristic findings at mammography, sonography, and color Doppler imaging and to evaluate the usefulness of color Doppler study as an additional modality in the diagnosis of phylloides tumor and differentiation between benign and malignant varieties. Eight cases, who were pathologically proven as pylloides tumors, were retrospectively studied. The findings at histologic examination suggested benign in five, malignantin two, and borderline in one. We analyzed the mammograms of all eight patients and sonogram and color Doppler images of four patients. Phylloides tumors were seen as dense masses with lobulated margins in mammograms. On sonography, they showed relatively well-defined masses with in homogenous internal echo pattern and central echogenic areas. They were characterized by the presence of arterial and venous flows in the center and periphery of the lesion on color Doppler imaging and spectral analysis. We conclude that mammographic, sonographic and even color Doppler findings are not predictive of benign or malignant nature of the phylloides tumor. However, mammography and sonography with color Doppler interrogation are helpful in the diagnosis of phylloides tumor

  3. Nonlinear Doppler - Free comb-spectroscopy in counter-propagating fields

    Pulkin, S A; Arnautov, V; Uvarova, S V; Savel'eva, S

    2014-01-01

    The method of Doppler - free comb - spectroscopy for dipole transitions was proposed. The calculations for susceptibility spectrum for moving two-level atoms driving by strong counter propagating combs have been done. The used theoretical method based on the Fourier expansion of the components of density matrix on two rows on kv (v-velocity of group of atoms, k-projection of wave vector) and {\\Omega} (frequency between comb components). For testing of validity of this method the direct numerical integration was done. The narrow peaks with homogeneous width arise on the background of Doppler counter. The contrast of these peaks is large for largest amplitudes of comb-components. Power broadening is increasing with increase of field amplitudes. The spectral range of absorption spectrum is determined by the spectral range of comb generator and all homogeneous lines arise simultaneously. The spectral resolution is determined by the width of homogeneously-broadening lines. The physical nature of narrow peaks is in...

  4. Doppler spectra and estimated windspeed of a violent tornado

    Presented in this paper are Doppler spectra of a very large tornado that occurred on 22 May 1981 near Binger, Oklahoma. Tracking of the tornado was accomplished with the help of a novel ''polar spectra display.'' Bimodal tornado spectral signatures (TSS) were observed in about 40 scans. Direct measurements of maximum velocities from spectral skirts yielded a maximum tangential speed of 80 m s-1 (90 m s-1 relative to ground). A diameter of 1 km at 200 m above ground was deduced from a simplified model. Radial centrifuging of radar targets was estimated to be about 20 m s-1. With simple assumptions for radar target sizes and summation of forces, a beamwidth average convergence value of abou 2.5 x 10-2 s-1 was calculated for the tornado boundary layer

  5. Spectral Ranking

    Vigna, Sebastiano

    2009-01-01

    This note tries to attempt a sketch of the history of spectral ranking, a general umbrella name for techniques that apply the theory of linear maps (in particular, eigenvalues and eigenvectors) to matrices that do not represent geometric transformations, but rather some kind of relationship between entities. Albeit recently made famous by the ample press coverage of Google's PageRank algorithm, spectral ranking was devised more than fifty years ago, almost exactly in the same terms, and has been studied in psychology and social sciences. I will try to describe it in precise and modern mathematical terms, highlighting along the way the contributions given by previous scholars.

  6. Doppler images of DI Piscium during 2004-2006

    Lindborg, M.; Hackman, T.; Mantere, M. J.; Korhonen, H.; Ilyin, I.; Kochukhov, O.; Piskunov, N.

    2014-02-01

    Aims: DI Psc (HD 217352) is a Li-rich, rapidly rotating single K giant. We set out to study the spot configuration and activity level by calculating surface temperature maps of the star. Methods: We apply the Doppler imaging method on high-resolution optical spectroscopy obtained during 2004-2006. Results: In July-August 2004, no clear spot structures were visible, but the spot coverage increased in July 2005, and cool spots emerged, especially at intermediate latitudes. Later on in September 2006, the spot coverage increased and cool spots were visible on both sides of the equator. However, the map of 2006 suffers from bad phase coverage, meaning it is not possible to draw definite conclusions on the spot locations during that season. Conclusions: Compared with earlier Doppler maps of DI Psc and temperature maps obtained for other late-type stars with similar rotation rates, DI Psc seems to be in a low activity state especially during the observing season of July-August 2004. During the 2005 and 2006 observing seasons, the spot activity seen in the spectral line profiles and inferred from Doppler images increases, and the temperature contrast in our last map is more comparable to what was reported in an earlier study. Therefore, it can be concluded that the spot activity level of the star is variable over time. However, the present and previous Doppler images form too short a time series to draw conclusions about a possible activity cycle in DI Psc. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

  7. DOPPLER ANALYSIS IN PREGNANCY INDUCED HYPERTENSION

    Tushar

    2014-12-01

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

  8. Doppler tomography in fusion plasmas and astrophysics

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

    2015-01-01

    spots, spiral structures and flow patterns. Fusion plasma Doppler tomography has led to an image of the fast-ion velocity distribution function in the tokamak ASDEX Upgrade. This image matched numerical simulations very well. Here we discuss achievements of the Doppler tomography approach, its promise...... and limits, analogies and differences in astrophysical and fusion plasma Doppler tomography and what can be learned by comparison of these applications....

  9. Observation of the Zero Doppler Effect

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

    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 i...

  10. Spectral density correction of a signal at frequency variable transformation

    Viorel NICOLAU

    2006-12-01

    Full Text Available The goal of this paper is to determine analytical expression for the spectral density function of a signal, affected by a known frequency transformation, which do not modify the process energy. Such transformations of frequency variable can frequently appear on spectral density function of a signal, due to physical events (e.g. Doppler effect or mathematical considerations (e.g. changing the coordinate system. In this case, all components of the spectral density function are modified. The formulas are valid for every spectral component and can be used in signal processing, for model simulation or implementation of advanced algorithm. A case study is illustrated on wave spectrum correction.

  11. Spectral Tagging

    This research examines the feasibility of spectral tagging, which involves modifying the spectral signature of a target, e.g. by mixing an additive with the target's paint. The target is unchanged to the human eye, but the tag is revealed when viewed with a spectrometer. This project investigates a layer of security that is not obvious, and therefore easy to conceal. The result is a tagging mechanism that is difficult to counterfeit. Uniquely tagging an item is an area of need in safeguards and security and non-proliferation. The powdered forms of the minerals lapis lazuli and olivine were selected as the initial test tags due to their availability and uniqueness in the visible to near-infrared spectral region. They were mixed with paints and applied to steel. In order to verify the presence of the tags quantitatively, the data from the spectrometer was input into unmixing models and signal detection algorithms. The mixture with the best results was blue paint mixed with lapis lazuli and olivine. The tag had a 0% probability of false alarm and a 100% probability of detection. The research proved that spectral tagging is feasible, although certain tag/paint mixtures are more detectable than others

  12. Single mode, extreme precision Doppler spectrographs

    Schwab, Christian; Betters, Christopher H; Bland-Hawthorn, Joss; Mahadevan, Suvrath

    2012-01-01

    The 'holy grail' of exoplanet research today is the detection of an earth-like planet: a rocky planet in the habitable zone around a main-sequence star. Extremely precise Doppler spectroscopy is an indispensable tool to find and characterize earth-like planets; however, to find these planets around solar-type stars, we need nearly one order of magnitude better radial velocity (RV) precision than the best current spectrographs provide. Recent developments in astrophotonics (Bland-Hawthorn & Horton 2006, Bland-Hawthorn et al. 2010) and adaptive optics (AO) enable single mode fiber (SMF) fed, high resolution spectrographs, which can realize the next step in precision. SMF feeds have intrinsic advantages over multimode fiber or slit coupled spectrographs: The intensity distribution at the fiber exit is extremely stable, and as a result the line spread function of a well-designed spectrograph is fully decoupled from input coupling conditions, like guiding or seeing variations (Ihle et al. 2010). Modal noise, a...

  13. Spectrally tunable pixel sensors

    Langfelder, G.; Buffa, C.; Longoni, A. F.; Zaraga, F.

    2013-01-01

    They are here reported the developments and experimental results of fully operating matrices of spectrally tunable pixels based on the Transverse Field Detector (TFD). Unlike several digital imaging sensors based on color filter arrays or layered junctions, the TFD has the peculiar feature of having electrically tunable spectral sensitivities. In this way the sensor color space is not fixed a priori but can be real-time adjusted, e.g. for a better adaptation to the scene content or for multispectral capture. These advantages come at the cost of an increased complexity both for the photosensitive elements and for the readout electronics. The challenges in the realization of a matrix of TFD pixels are analyzed in this work. First experimental results on an 8x8 (x 3 colors) and on a 64x64 (x 3 colors) matrix will be presented and analyzed in terms of colorimetric and noise performance, and compared to simulation predictions.

  14. Airborne Differential Doppler Weather Radar

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

    2001-01-01

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

  15. Six-wave mixing spectroscopy in a Doppler-broadened cascade four-level system

    Niu Jinyan; Wang Ruquan; Wang Bingbing; Wu Lingan; Fu Panming, E-mail: pmfu@aphy.iphy.ac.c [Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2009-09-14

    We study six-wave mixing (SWM) spectroscopy based on electromagnetically induced transparency in a Doppler-broadened cascade four-level system. It is found that the SWM spectra are extremely sensitive to the configuration of the incident beams, where the linewidth can be either Doppler-free or very broad, due to the polarization interference of atoms of different velocities. This polarization interference can be controlled in the presence of a strong coupling field. Moreover, SWM can be employed as a new type of Doppler-free Autler-Townes (AT) spectroscopy, which has better spectral resolution than conventional AT spectroscopy. Finally, we also reveal the intrinsic connection between frequency-domain SWM spectroscopy and time-domain photon echoes through studying the time-domain correspondence of SWM.

  16. Microwave Doppler radar in unobtrusive health monitoring

    This article frames the use of microwave Doppler radar in the context of ubiquitous, non-obstructive health monitoring. The use of a 24GHz CW (continuous wave) Doppler radar based on a commercial off-the-shelf transceiver for remote sensing of heart rate and respiration rate based on the acquisition and processing of the signals delivered by the radar is briefly presented

  17. Fresh look at the doppler changes in pregnancies with placental-based complications

    S Dikshit

    2011-01-01

    Full Text Available Placental-based complications of pregnancy can be classified as acute and chronic. An example of acute placental complication is abruptio placenta. The chronic placental complications include pregnancy induced hypertension (PIH and idiopathic Intrauterine growth restriction (IUGR. The fetus is at risk for perinatal complications in both acute and chronic conditions. Here we take a look at the natural history of the Doppler parameters in chronic conditions. The techniques used for assessing the fetal well-being include, clinical methods, biophysical tests, conventional ultrasonography, and fetal Doppler studies. Arterial Doppler studies are used to assess the well-being of the fetus and to determine the timing of delivery. However, arterial Dopplers predict only the subset of fetuses at risk of having perinatal complications. Venous Dopplers have been used to improve upon the prognostication. However, by the time the commonly used venous Doppler signs, that is, ′A′ wave reversal in ductus venosus (DV is present, the fetus is likely to be already compromised. The fetus tries to adapt to the environment of deprivation by making a series of changes in the umbilical artery circulation, cerebral circulation, and hepatic circulation. As a result of these adaptations, the fetus overcomes the state of chronic hypoxia. This article takes a look at these changes and also the effect of these adaptations. It is suggested that serial comparisons of the venous flow characteristics of the DV and inferior vena cava (IVC can provide an early indication of the impending decompensation and can be used to predict the time the delivery.

  18. Observation of the Zero Doppler Effect

    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.

  19. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    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

  20. Color doppler sonography in thickened gallbladder wall

    Han, Sang Suk; Choi, Seok Jin; Seo, Chang Hae; Eun, Choong Ki [Inje Univ. College of Medicine, Kimhae (Korea, Republic of)

    1996-11-01

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

  1. Color doppler sonography in thickened gallbladder wall

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

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

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

    2012-12-01

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

  3. LISA data analysis: Doppler demodulation

    The orbital motion of the laser interferometer space antenna (LISA) produces amplitude, phase and frequency modulations of a gravitational wave signal. The modulations have the effect of spreading a monochromatic gravitational wave signal across a range of frequencies. The modulations encode useful information about the source location and orientation, but they also have the deleterious effect of spreading a signal across a wide bandwidth, thereby reducing the strength of the signal relative to the instrument noise. We describe a simple method for removing the dominant, Doppler component of the signal modulation. The demodulation reassembles the power from a monochromatic source into a narrow spike and provides a quick way to determine the sky locations and frequencies of the brightest gravitational wave sources

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

    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 vasoconstriction with an increase in blood pressure and a decrease in heart rate and femoral flow.(ABSTRACT TRUNCATED AT 250 WORDS).

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

    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 pressure and heart rate did not change significantly. The femoral resistance index (Rf) increased by an average of 37.5% (p blood pressure and a decrease in heart rate and femoral flow.(ABSTRACT TRUNCATED AT 250 WORDS).

  6. Doppler-ultrasonographic finding of air in the portal vein: a case report

    Park, Ki Soon; Lee, Kwan Sup; Lee, Yul; Chung, Soo Young; Bae, Sang Hoon [College of Medicine, Hallym University, Seoul (Korea, Republic of)

    1994-03-15

    Classically air in the portal vein has been detected on plain radiography, but computed tomography and ultrasonography have been shown to be more sensitive. We report a case of air in the PV in a 10-day-old infant with pneumatosis intestinalis with its ultrasonographic and Doppler findings. The patient was a 10-day-old infant born by cesarean section at 41 weeks. Simple abdomen film revealed branching pattern of radiolucent air shadows within in contour of liver, gas distention of bowel loops and thickenod bowel walls with lincar intraluminal air shadows in abdomen, suggesting necrotizing enterocolitis. So we performed Doppler ultrasonography. Ultrasonography showed branching pattern of hyperechogenic dots and along the lumen of left portal vein. The color Doppler study revealed an aliasing duo to increased velocity and whirling pattern of blood flow, and the Duplex Doppler spectral display showed sharp, vertical bidirectional spikes by air in portal vein. Air in the portal vein can be easily diagnosed by the following signs: hyperechogenic dots in the portal vein on ultrasonography and vertical, sharp bidirectional spikes superimposed on the usual Doppler tracing of the portal vein on Duplex ultrasonography.

  7. Feasibility Study of Using Gemstone Spectral Imaging (GSI and Adaptive Statistical Iterative Reconstruction (ASIR for Reducing Radiation and Iodine Contrast Dose in Abdominal CT Patients with High BMI Values.

    Zheng Zhu

    Full Text Available To prospectively investigate the effect of using Gemstone Spectral Imaging (GSI and adaptive statistical iterative reconstruction (ASIR for reducing radiation and iodine contrast dose in abdominal CT patients with high BMI values.26 patients (weight > 65kg and BMI ≥ 22 underwent abdominal CT using GSI mode with 300mgI/kg contrast material as study group (group A. Another 21 patients (weight ≤ 65kg and BMI ≥ 22 were scanned with a conventional 120 kVp tube voltage for noise index (NI of 11 with 450mgI/kg contrast material as control group (group B. GSI images were reconstructed at 60keV with 50%ASIR and the conventional 120kVp images were reconstructed with FBP reconstruction. The CT values, standard deviation (SD, signal-noise-ratio (SNR, contrast-noise-ratio (CNR of 26 landmarks were quantitatively measured and image quality qualitatively assessed using statistical analysis.As for the quantitative analysis, the difference of CNR between groups A and B was all significant except for the mesenteric vein. The SNR in group A was higher than B except the mesenteric artery and splenic artery. As for the qualitative analysis, all images had diagnostic quality and the agreement for image quality assessment between the reviewers was substantial (kappa = 0.684. CT dose index (CTDI values for non-enhanced, arterial phase and portal phase in group A were decreased by 49.04%, 40.51% and 40.54% compared with group B (P = 0.000, respectively. The total dose and the injection rate for the contrast material were reduced by 14.40% and 14.95% in A compared with B.The use of GSI and ASIR provides similar enhancement in vessels and image quality with reduced radiation dose and contrast dose, compared with the use of conventional scan protocol.

  8. Measuring Velocity and Acceleration Using Doppler Shift of a Source with an Example of Jet in SS433

    Sanjay M. Wagh

    2014-12-01

    We describe here as to how the Doppler shift of a source needs to be used to measure its velocity and acceleration. We also apply this method, as an example here, to spectral lines of the blue-shifted jet in micro-quasar SS433 and discuss the intricacies of these measurements.

  9. An FPGA-based Doppler Processor for a Spaceborne Precipitation Radar

    Durden, S. L.; Fischman, M. A.; Johnson, R. A.; Chu, A. J.; Jourdan, M. N.; Tanelli, S.

    2007-01-01

    Measurement of precipitation Doppler velocity by spaceborne radar is complicated by the large velocity of the satellite platform. Even if successive pulses are well correlated, the velocity measurement may be biased if the precipitation target does not uniformly fill the radar footprint. It has been previously shown that the bias in such situations can be reduced if full spectral processing is used. The authors present a processor based on field-programmable gate array (FPGA) technology that can be used for spectral processing of data acquired by future spaceborne precipitation radars. The requirements for and design of the Doppler processor are addressed. Simulation and laboratory test results show that the processor can meet real-time constraints while easily fitting in a single FPGA.

  10. Rotational Doppler effect in nonlinear optics

    Li, Guixin; Zentgraf, Thomas; Zhang, Shuang

    2016-08-01

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

  11. Color doppler ultrasonography diagnosis of intramuscular hemangioma

    Objective: To analyze the clinical application of color Doppler ultrasonography in diagnosing intramuscular hemangioma. Methods: The color Doppler ultrasonographic characteristics of 17 cases with intramuscular hemangioma were analyzed retrospectively. Results: Seventeen patients with intramuscular hemangima were examined and diagnosed, and all these cases were confirmed by pathology after operation. The diagnostic accurate rate was 100%. Conclusion: Intramuscular hemangioma possesses typical characteristics in two-dimensional ultrasound. On the base of two-dimensional image, Color Doppler Flow Imaging can show blood vessel distribution of intramuscular hemangioma. So intramuscular hemangioma can be measured accurately. (authors)

  12. Preliminary simulation study of doppler reflectometry

    A preliminary simulation study of Doppler reflectometry is performed. The simulations solve Maxwell's equations by a finite difference time domain (FDTD) code method in two dimensions. A moving corrugated metal target is used as a plasma cutoff layer to study the basic features of Doppler reflectometry. We examined the effects of the full width at half maximum (FWHM) of the electromagnetic waves and the corrugation depth of the metal target. Furthermore, the effect of a nonuniform plasma is studied using this FDTD analysis. The Doppler shift and velocity are compared with those obtained from FDTD analysis of a uniform plasma. (author)

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

    Dadashi, Neda; Teriaca, Luca; Solanki, Sami K.

    2011-01-01

    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. ...

  14. Fetal cerebral-umbilical Doppler ratio in prediction of fetal distress in patients with preeclampsia

    Jurišić Aleksandar; Jurišić Žaklina; Pažin Vladimir; Vasiljević Mladenko; Janković-Ražnatović Svetlana; Dragojević-Dikić Svetlana

    2010-01-01

    Bacground/Aim. The use of color Doppler ultrasonography provides noninvasive observation, confirmation and quantification of pathophysiological processes in fetoplacental circulation in pregnant patients. By blood vessel mapping and the obtained waves spectral analysis it is possible to evaluate vascular resistency of the fetus blood vessels. The aim of the study was to evaluate cerebral-umbilical pulsatility index ratio in fetal circulation in prediction of fetal distress in patients with pr...

  15. Single Mode, Extreme Precision Doppler Spectrographs

    Schwab, Christian; Leon-Saval, Sergio G.; Betters, Christopher H.; Bland-Hawthorn, Joss; Mahadevan, Suvrath

    2014-04-01

    The `holy grail' of exoplanet research today is the detection of an earth-like planet: a rocky planet in the habitable zone around a main-sequence star. Extremely precise Doppler spectroscopy is an indispensable tool to find and characterize earth-like planets; however, to find these planets around solar-type stars, we need nearly one order of magnitude better radial velocity (RV) precision than the best current spectrographs provide. Recent developments in astrophotonics (Bland-Hawthorn & Horton 2006, Bland-Hawthorn et al. 2010) and adaptive optics (AO) enable single mode fiber (SMF) fed, high resolution spectrographs, which can realize the next step in precision. SMF feeds have intrinsic advantages over multimode fiber or slit coupled spectrographs: The intensity distribution at the fiber exit is extremely stable, and as a result the line spread function of a well-designed spectrograph is fully decoupled from input coupling conditions, like guiding or seeing variations (Ihle et al. 2010). Modal noise, a limiting factor in current multimode fiber fed instruments (Baudrand & Walker 2001), can be eliminated by proper design, and the diffraction limited input to the spectrograph allows for very compact instrument designs, which provide excellent optomechanical stability. A SMF is the ideal interface for new, very precise wavelength calibrators, like laser frequency combs (Steinmetz et al. 2008, Osterman et al. 2012), or SMF based Fabry-Perot Etalons (Halverson et al. 2013). At near infrared wavelengths, these technologies are ready to be implemented in on-sky instruments, or already in use. We discuss a novel concept for such a spectrograph.

  16. Pulmonary Impedance and Pulmonary Doppler Trace in the Perioperative Period.

    Tousignant, Claude; Van Orman, Jordan R

    2015-09-01

    Pulmonary hypertension and associated vascular changes may frequently accompany left-sided heart disease in the adult cardiac surgical population. Perioperative assessment of right ventricular function using echocardiography is well established. In general, understanding the constraints upon which the right ventricle must work is mostly limited to invasive monitoring consisting of pulmonary artery pressures, cardiac output, and pulmonary vascular resistance. The latter 2 measurements assume constant (mean) flows and pressures. The systolic and diastolic pressures offer a limited understanding of the pulsatile constraints, which may become significant in disease. In normal physiology, pressure and flow waves display near-similar contours. When left atrial pressure and pulmonary vascular resistance are increased, changes in pulmonary arterial compliance will result in elevated impedance to right ventricular ejection. Pressure reflections, the result of strong reflectors, return more quickly in a noncompliant system. They augment pulmonary artery pressure causing a premature reduction in flow. As a result, pressure and flow waves will now be dissimilar. The impact of vascular changes on right ventricular ejection can be assessed using pulmonary artery Doppler spectral imaging. The normal flow velocity profile is rounded at its peak. Earlier peaks and premature reductions in flow will make it appear more triangular. In some cases, the flow pattern may appear notched. The measurement of acceleration time, the time from onset to peak flow velocity is an indicator of constraint to ejection; shortened times have been associated with increased pulmonary vascular resistance and pressure. Understanding the changes in the pulmonary arterial system in disease and the physics of the hemodynamic alterations are essential in interpreting pulmonary artery Doppler data. Analyzing pulmonary artery Doppler flow signals may assist in the evaluation of right ventricular function in

  17. Colour doppler ultrasound assessment of the normal neonatal hip

    To determine the morphology and hemodynamic characteristics of the arterial vessels of the proximal femur according to specific anatomic regions in asymptomatic neonates in 2 pediatric-based health care institutions. Forty-three neonates (29 female, 14 male; age range, 2 d-3 mo; median age, 3 d) were enrolled in the study. Thirty-two (37%) of 86 hips were classified as Graf type IIA joints (mean alpha angle, 56.0o ± 2.7o), and 54 (63%) were classified as type I joints (mean alpha angle, 65.0o ± 4.6o). Colour and spectral Doppler imaging identified vessels running along the acetabular labrum, epiphyseal vessels, and femoral neck. We showed 4 different patterns of vascularity of the hips: radial, parallel, mixed radial-parallel, and indeterminate, however, they were not related to the hip maturity (P = .3, coronal plane; P = .62, transverse plane) or to the amount of colour pixels identified in each region (P = .35). The mean number of pixels in the ligamentum teres region was significantly higher than that in other regions of interest (P =.03). Except for the acetabular labrum arteries, Doppler spectrum waveforms of proximal femur arteries presented with low resistivity. There was a tendency towards females' acetabular arteries presenting with lower peak systolic velocities than males' acetabular arteries (P =.06). Colour Doppler spectrum waveforms and intensity of vascularity in normal neonatal hips differ according to the anatomic region under evaluation. This observation deserves further investigation on its role on the physiopathogenesis of neonatal hip disorders. (author)

  18. Colour doppler ultrasound assessment of the normal neonatal hip

    Ortiz-Neira, C.L. [Dept. of Diagnostic Imaging, Alberta Children' s Hospital, Calgary, Alberta (Canada)], E-mail: clara.ortiz@calgaryhealthregion.ca; Laffan, E.; Daneman, A. [Dept. of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario (Canada); Fong, K. [Dept. of Diagnostic Imaging, Mount Sinai Hospital, Toronto, Ontario (Canada); Roposch, A. [Dept. of Orthopedic Surgery, The Hospital for Sick Children, Toronto, Ontario (Canada); Great Ormond Street Hospital, Inst. of Child Health, Univ. College London, London (United Kingdom)

    2009-04-15

    To determine the morphology and hemodynamic characteristics of the arterial vessels of the proximal femur according to specific anatomic regions in asymptomatic neonates in 2 pediatric-based health care institutions. Forty-three neonates (29 female, 14 male; age range, 2 d-3 mo; median age, 3 d) were enrolled in the study. Thirty-two (37%) of 86 hips were classified as Graf type IIA joints (mean alpha angle, 56.0{sup o} {+-} 2.7{sup o}), and 54 (63%) were classified as type I joints (mean alpha angle, 65.0{sup o} {+-} 4.6{sup o}). Colour and spectral Doppler imaging identified vessels running along the acetabular labrum, epiphyseal vessels, and femoral neck. We showed 4 different patterns of vascularity of the hips: radial, parallel, mixed radial-parallel, and indeterminate, however, they were not related to the hip maturity (P = .3, coronal plane; P = .62, transverse plane) or to the amount of colour pixels identified in each region (P = .35). The mean number of pixels in the ligamentum teres region was significantly higher than that in other regions of interest (P =.03). Except for the acetabular labrum arteries, Doppler spectrum waveforms of proximal femur arteries presented with low resistivity. There was a tendency towards females' acetabular arteries presenting with lower peak systolic velocities than males' acetabular arteries (P =.06). Colour Doppler spectrum waveforms and intensity of vascularity in normal neonatal hips differ according to the anatomic region under evaluation. This observation deserves further investigation on its role on the physiopathogenesis of neonatal hip disorders. (author)

  19. TU-A-9A-02: Analysis of Variations in Clinical Doppler Ultrasound Peak Velocity Measurements

    Purpose: Doppler ultrasound (US) peak velocity (Vmax) measurements show considerable variations due to intrinsic spectral broadening with different scanning techniques, machines and manufacturers. We developed a semi-automated Vmax estimation method and used this method to investigate the performance of a US system for clinical Doppler Vmax measurement. Methods: Semi-automated Vmax is defined as the velocity at which the computed mean spectral profile falls to within 1 background standard deviation of the background mean. GE LOGIQ E9 system with 9L and ML6-15 probes were studied with steady flow (5.3 – 12.5 ml/s) in a Gammex OPTIMIZER 1425A phantom. All Doppler spectra were acquired by 1 operator at the distal end of 5 mm angular tube using a modified clinical carotid artery protocol. Repeatability and variation of Vmax to scanning parameters and probes were analyzed and reported as percentage, i.e. (max-min)/mean. Results: Vmax estimation had good repeatability (3.1% over 6 days for 9L, and 3.6% for ML6-15). For 9L probe, varying gain, compression, scale, SV depth and length, and frequency had minimal impact on Vmax (all variations less than 4.0%). Beam steering had slightly higher influence (largest variations across flow rates were 4.9% for 9L and 6.9% for ML6-15). For both probes, Doppler angle had the greatest effect on Vmax. Percentage increase of Vmax was largely independent of actual flow rates. For Doppler angle varied from 30 to 60°, Vmax increased 24% for 9L, and 20% for ML6-15. Vmax measured by ML6-15 were lower than that by 9L at each Doppler angle with differences less than 5%. Conclusion: The proposed Vmax estimation method is shown to be a useful tool to evaluate clinical Doppler US system performance. For the tested system and probes, Doppler angle had largest impact in measured Vmax

  20. Steering A Radar Beam Toward The Zero-Doppler Line

    Chang, Chi-Yung; Curlander, John C.

    1994-01-01

    Algorithm computes angles needed to aim radar beam from airborne or spaceborne platform toward Doppler line projected on ground for which Doppler shift of radar return is zero. Devised to reduce Doppler errors and simplify processing of data from synthetic-aperture-radar system. Applicable to aiming of other radio or optical instruments toward their zero-Doppler lines on ground.

  1. Doppler shifted H Ly α emission from Jupiter's aurora

    IUE observations of the aurora on Jupiter have been performed with high spectral resolution in a search for Doppler shifted H Ly α emission produced through charge exchange by fast precipitating protons, as observed in the Earth's aurora. No emission has been observed corresponding to proton energies greater than 200 eV, placing a strict upper limit on the contribution of KeV - MeV protons to the production of Jupiter's aurora. However, a large fraction of the H Ly α emission has appeared Doppler-shifted mainly toward the blue by roughly 50 km/sec, corresponding to a kinetic energy of 10-20 eV for a fast proton or H atom, and there are higher velocity wings on the line extending out to equivalent energies of 150-200 eV. The blue shift indicates motion up out of the atmosphere, and the authors suggest that the emission results from the in situ acceleration of ionospheric protons in Jupiter's auroral ionosphere by analogy to the ionospheric potentials observed in the Earth's auroral zones. These observations demonstrate that the acceleration of ionospheric plasma in an H2 atmosphere can lead to bright Ly α emission, with implications for the production of the outer planet airglow emissions

  2. Doppler disc tomography applied to low mass AGN spin

    Middleton, Matthew

    2014-01-01

    Doppler tomography can provide a powerful means of determining black hole spin when our view to the central regions are revealed and obscured by optically thick orbiting material, and can provide an independent estimate that does not suffer as many degeneracies as traditional methods. For low mass AGN, time-dependent obscuration is expected to leave a signature in the changing spectrum of the disc emission which extends into the soft X-ray bandpass. We create a spectral model incorporating Doppler tomography and apply it to the case of the low mass (8$\\times$10$^{5}$ M$_{\\odot}$) AGN, RX J1301.9+2747 which shows unusual timing properties in the form of short-lived flares that we argue are best explained by the orbit of a window through an optically thick wind. Modelling the phase-resolved spectrum over the course of the highest data quality flare indicates a very low spin even when we relax our constraints. This is the lowest mass AGN for which a spin has been measured and the first via this technique. We not...

  3. Doppler disc tomography applied to low-mass AGN spin

    Middleton, Matthew J.; Ingram, Adam R.

    2015-01-01

    Doppler tomography can provide a powerful means of determining black hole spin when our view to the central regions are revealed and obscured by optically thick orbiting material, and can provide an independent estimate that does not suffer as many degeneracies as traditional methods. For low-mass active galactic nuclei (AGN), time-dependent obscuration is expected to leave a signature in the changing spectrum of the disc emission which extends into the soft X-ray bandpass. We create a spectral model incorporating Doppler tomography and apply it to the case of the low-mass (8 × 105 M⊙) AGN, RX J1301.9+2747 which shows unusual timing properties in the form of short-lived flares that we argue are best explained by the orbit of a window through an optically thick wind. Modelling the phase-resolved spectrum over the course of the highest data quality flare indicates a very low spin even when we relax our constraints. This is the lowest mass AGN for which a spin has been measured and the first via this technique. We note that, as the mass and spin are very low, this appears to favour supermassive black hole (SMBH) growth by chaotic rather than constant accretion.

  4. The first Doppler images of the eclipsing binary SZ Piscium

    Xiang, Yue; Gu, Shenghong; Cameron, A. Collier; Barnes, J. R.; Zhang, Liyun

    2016-02-01

    We present the first Doppler images of the active eclipsing binary system SZ Psc, based on the high-resolution spectral data sets obtained in 2004 November and 2006 September-December. The least-squares deconvolution technique was applied to derive high signal-to-noise profiles from the observed spectra of SZ Psc. Absorption features contributed by a third component of the system were detected in the LSD profiles at all observed phases. We estimated the mass and period of the third component to be about 0.9 M⊙ and 1283 ± 10 d, respectively. After removing the contribution of the third body from the least-squares deconvolved profiles, we derived the surface maps of SZ Psc. The resulting Doppler images indicate significant star-spot activities on the surface of the K subgiant component. The distributions of star-spots are more complex than that revealed by previous photometric studies. The cooler K component exhibited pronounced high-latitude spots as well as numerous low- and intermediate-latitude spot groups during the entire observing seasons, but did not show any large, stable polar cap, different from many other active RS CVn-type binaries.

  5. The first Doppler images of the eclipsing binary SZ Piscium

    Xiang, Yue; Cameron, A Collier; Barnes, J R; Zhang, Liyun

    2015-01-01

    We present the first Doppler images of the active eclipsing binary system SZ Psc, based on the high-resolution spectral data sets obtained in 2004 November and 2006 September--December. The least-squares deconvolution technique was applied to derive high signal-to-noise profiles from the observed spectra of SZ Psc. Absorption features contributed by a third component of the system were detected in the LSD profiles at all observed phases. We estimated the mass and period of the third component to be about $0.9 M_{\\odot}$ and $1283 \\pm 10$ d, respectively. After removing the contribution of the third body from the LSD profiles, we derived the surface maps of SZ Psc. The resulting Doppler images indicate significant starspot activities on the surface of the K subgiant component. The distributions of starspots are more complex than that revealed by previous photometric studies. The cooler K component exhibited pronounced high-latitude spots as well as numerous low- and intermediate-latitude spot groups during the...

  6. A new parametric approach for wind profiling with Doppler Radar

    Le Foll, GwenaëLle; Larzabal, Pascal; Clergeot, Henri; Petitdidier, Monique

    1997-07-01

    In this paper, we propose a new approach for wind profile extraction with Doppler radar. To perform this, we first focus on the analysis and modeling of VHF or UHF waves backscattered by clear-air turbulence. A physical description of the backscattered wave is given. This description involves a spectral model that includes a parametric profile of the Doppler spectrum. A parametric approach of the wind profile can be easily generated. The sounding volume is divided into slabs whose thickness is consistent with that of the expected homogeneous turbulent layer. The echo spectrum of each slab is supposed Gaussian. Thus, for the range gate, the backscattered spectrum is a priori non-Gaussian, since it is weighted by a nonconstant reflectivity. This represents a more realistic assumption than the classical ones. The realistic temporal model thereby obtained can be used in simulation, which provides a valable tool for testing the extraction algorithm. An original recursive fitting, in terms of maximum likelihood, between the experimentally recorded spectrum and the parametric candidate spectrum is described and implemented as a second-order, steepest-descent algorithm. This optimization problem is solved in a weighted fashion on the entire gate simultaneously. The regularized parametric method, described in this paper, is a way to minimize some of the drawbacks encountered with traditional methods. Simulations reveal good statistical performance compared with traditional methods. The algorithm is then tested on real data. To achieve this, original methods are proposed for noise suppression and clutter removal.

  7. High Throughput Direct Detection Doppler Lidar Project

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

  8. INSTANTANEOUS DOPPLER FREQUENCY FOR SQUINT SAR IMAGING

    Liu Guangyan; Huang Shunji

    2003-01-01

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

  9. Student Microwave Experiments Involving the Doppler Effect.

    Weber, F. Neff; And Others

    1980-01-01

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

  10. Doppler coefficient measurements in Zebra Core 5

    Measurements using a central hot loop in Zebra Core 5 are described. Results are given for the Doppler coefficients found in a number of assemblies with PuO2 and 16% PuO2/84% depleted UO2 pins, loaded with different combinations of steel, sodium or void pins. The mixed oxide results are in general about 20% more negative than was calculated using the FD2 data set, but agreement is good if the plutonium contributions in the calculations are omitted. The small positive Doppler coefficient calculated for Pu239 was not observed, and two measurements indicated instead a small negative effect. The Doppler effect in the mixed oxide systems was found to vary approximately as 1/T. The results from the empty loop and non-fissile assemblies indicate either a small negative Doppler effect in steel or alternatively the presence of an unexplained expansion effect. (author)

  11. Intensity changes in the Doppler effect

    Johnson, Montgomery H.; Teller, Edward

    1982-01-01

    When a source moves in any direction, the source strength and the frequencies are altered by the Doppler effect. It is shown that the source strength divided by the cube of the frequency is a Lorentz invariant.

  12. Micro-Doppler Frequency Comb Generation by Axially Rotating Scatterers

    Kozlov, Vitali; Yankelevich, Yefim; Ginzburg, Pavel

    2016-01-01

    Electromagnetic scattering in accelerating reference frames inspires a variety of phenomena, requiring employment of general relativity for their description. While the quasi-stationary field analysis could be applied to slowly-accelerating bodies as a first-order approximation, the scattering problem remains fundamentally nonlinear in boundary conditions, giving rise to multiple frequency generation (micro-Doppler shifts). Here a frequency comb, generated by an axially rotating subwavelength (cm-range) wire and split ring resonator (SRR), is analyzed theoretically and observed experimentally by illuminating the system with a 2GHz carrier wave. Highly accurate lock in detection scheme enables factorization of the carrier and observation of more than ten peaks in a comb. The Hallen integral equation is employed for deriving the currents induced on the scatterer at rest and a set of coordinate transformations, connecting laboratory and rotating frames, is applied in order to predict the spectral positions and a...

  13. Laser Doppler flowmetry in microvascular surgery

    Adrichem, Léon

    1992-01-01

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

  14. Speckles in laser Doppler perfusion imaging

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

    2006-01-01

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

  15. Optical Doppler shift with structured light

    Belmonte A.; Belmonte, Aniceto; de Torres, Juan P; Torres J.P.

    2011-01-01

    When a light beam with a transverse spatially varying phase is considered for optical remote sensing, in addition to the usual longitudinal Doppler frequency shift of the returned signal induced by the motion of the scatter along the beam axis, a new transversal Doppler shift appears associated to the motion of the scatterer in the plane perpendicular to the beam axis. We discuss here how this new effect can be used to enhance the current capabilities of optical measurement system...

  16. with Ultrasound Color Doppler Imaging

    Shin Takayama

    2012-01-01

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

  17. Doppler synthetic aperture hitchhiker imaging

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

  18. Color Doppler Ultrasound Indices in Endometriotic Cysts

    Parisa Hajialioghlo

    2009-01-01

    Full Text Available Problem statement: There have been considerable interests on using non-invasive techniques to detect endometriosis. A few studies were evaluated the Doppler ultrasound findings of endometriosis. This study aimed to characterize the grayscale and Doppler ultrasound findings of endometriosis. Approach: During present prospective study, gray scale and Doppler ultrasound findings of 37 women with final diagnosis of endometriosis were evaluated. Patients with probable diagnosis of endometriosis underwent conventional transvaginal and color Doppler assessment. After laparascopic confirmation of endometriosis, gray scale and color Doppler ultrasonographic data of patients considered for analysis. Results: Finally data of 37 subjects' data with suspected endometriosis was analyzed. Twenty nine of lesions were endometriosis, five hydrosalpinx, four paraovarian adhesion cysts and one peritoneal inclusion cyst according to laparoscopic exploration. Out of 29 endometriotic cysts, flow was detected in 58.62%. The mean of RI and PI were 0.67±0.15 (0.46-1.00 and 1.49±0.85 (0.66-3.11, respectively. Conclusion: In our experience, transvaginal sonography with color Doppler interrogation is a useful technique in the diagnosis of pathologic ovarian conditions, including cystic endometriosis.

  19. Doppler micro sense and avoid radar

    Gorwara, Ashok; Molchanov, Pavlo; Asmolova, Olga

    2015-10-01

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

  20. Correlation-induced spectral changes

    Wolf, Emil; James, Daniel F. V.

    1996-06-01

    This paper presents a review of research, both theoretical and experimental, concerning the influence of coherence properties of fluctuating light sources and of correlation properties of scattering media on the spectra of radiated and scattered fields. Much of this research followed a discovery made in 1986, that the spectrum of light may change on propagation, even in free space. More than 100 papers on this topic have been published to date and many of them are reviewed, or at least mentioned, in this article. After an introduction and a summary of some of the main mathematical results relating to second-order coherence theory of statistically stationary optical fields, spectral changes that may take place on superposing fields produced by two partially correlated sources are discussed. Spectral effects in fields produced by two-dimensional secondary sources and by three-dimensional primary sources are then considered. The section which follows describes spectral changes that may arise when polychromatic light is scattered on media whose physical properties vary randomly either in space and/or in time. A review is also presented of recent research, which has revealed that under certain circumstances the changes in the spectrum of light scattered on random media may imitate the Doppler effect, even though the source, the medium and the observer are all at rest with respect to one another. In the final section a brief review is given of a new emerging technique sometimes called spatial-coherence spectroscopy. It is based on the discovery that it is possible, under certain circumstances, to determine field correlations from spectral measurements.

  1. Correlation-induced spectral changes

    This paper presents a review of research, both theoretical and experimental, concerning the influence of coherence properties of fluctuating light sources and of correlation properties of scattering media on the spectra of radiated and scattered fields. Much of this research followed a discovery made in 1986, that the spectrum of light may change on propagation, even in free space. More than 100 papers on this topic have been published to date and many of them are reviewed, or at least mentioned, in this article. After an introduction and a summary of some of the main mathematical results relating to second-order coherence theory of statistically stationary optical fields, spectral changes that may take place on superposing fields produced by two partially correlated sources are discussed. Spectral effects in fields produced by two-dimensional secondary sources and by three-dimensional primary sources are then considered. The section which follows describes spectral changes that may arise when polychromatic light is scattered on media whose physical properties vary randomly either in space and/or in time. A review is also presented of recent research, which has revealed that under certain circumstances the changes in the spectrum of light scattered on random media may imitate the Doppler effect, even though the source, the medium and the observer are all at rest with respect to one another. In the final section a brief review is given of a new emerging technique sometimes called spatial-coherence spectroscopy. It is based on the discovery that it is possible, under certain circumstances, to determine field correlations from spectral measurements. (author)

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

    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 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.

  3. Left ventricular radial colour and longitudinal pulsed-wave tissue Doppler echocardiography in 39 healthy domestic pet rabbits.

    Casamian-Sorrosal, Domingo; Saunders, Richard; Browne, William; Elliot, Sarah; Fonfara, Sonja

    2014-10-01

    This paper reports radial colour and longitudinal mitral annulus pulsed-wave tissue Doppler findings in a large cohort of healthy, adult pet rabbits. Thirty-nine rabbits (22 Dwarf Lops, 14 French Lops and three Alaskans) underwent conscious echocardiography. The median age of the rabbits was 22 months and the median weight was 2.8 kg (Dwarf Lop 2.4 kg/French Lop 6.0 kg). Adequate radial colour and longitudinal pulsed-wave tissue Doppler traces were obtained in 100% and 85% of cases, respectively. Most systolic tissue Doppler parameters were significantly higher in French Lops than in Dwarf Lops. Separation of mitral inflow diastolic waves was present in 40% of cases using conventional spectral Doppler and in >60% of cases using pulsed-wave tissue Doppler which could be beneficial when evaluating diastolic function in rabbits. This study can be used as a reference for normal echocardiographic tissue Doppler values for adult rabbits undergoing conscious echocardiography in clinical practice. PMID:25089025

  4. Densities, Spectral Densities and Modality

    Davies, PL Laurie; Kovac, A.

    2002-01-01

    This paper considers the problem of specifying a simple approximating density function for a given data set (x1,…,xn). Simplicity is measured by the number of modes but several different definitions of approximation are introduced. The taut string method is used to control the numbers of modes and to produce candidate approximating densities. Refinements are introduced that improve the local adaptivity of the procedures and the method is extended to spectral densities.

  5. Ultrasonography with color Doppler and power Doppler in the diagnosis of periapical lesions

    Sumit Goel

    2011-01-01

    Full Text Available Aim: To evaluate the efficacy of ultrasonography (USG with color Doppler and power Doppler applications over conventional radiography in the diagnosis of periapical lesions. Materials and Methods: Thirty patients having inflammatory periapical lesions of the maxillary or mandibular anterior teeth and requiring endodontic surgery were selected for inclusion in this study. All patients consented to participate in the study. We used conventional periapical radiographs as well as USG with color Doppler and power Doppler for the diagnosis of these lesions. Their diagnostic performances were compared against histopathologic examination. All data were compared and statistically analyzed. Results: USG examination with color Doppler and power Doppler identified 29 (19 cysts and 10 granulomas of 30 periapical lesions accurately, with a sensitivity of 100% for cysts and 90.91% for granulomas and a specificity of 90.91% for cysts and 100% for granulomas. In comparison, conventional intraoral radiography identified only 21 lesions (sensitivity of 78.9% for cysts and 45.4% for granulomas and specificity of 45.4% for cysts and 78.9% for granulomas. There was definite correlation between the echotexture of the lesions and the histopathological features except in one case. Conclusions: USG imaging with color Doppler and power Doppler is superior to conventional intraoral radiographic methods for diagnosing the nature of periapical lesions in the anterior jaws. This study reveals the potential of USG examination in the study of other jaw lesions.

  6. Spectral Hole Burning via Kerr Nonlinearity

    Khan, Anwar Ali; Abdul Jabar, M. S.; Jalaluddin, M.; Bacha, Bakht Amin; Iftikhar, Ahmad

    2015-10-01

    Spectral hole burning is investigated in an optical medium in the presence of Doppler broadening and Kerr nonlinearity. The Kerr nonlinearity generates coherent hole burning in the absorption spectrum. The higher order Kerr nonlinearity enhances the typical lamb dip of the hole. Normal dispersion in the hole burning region while Steep anomalous dispersion between the two hole burning regions also enhances with higher order Kerr effect. A large phase shift creates large delay or advancement in the pulse propagation while no distortion is observed in the pulse. These results provide significant steps to improve optical memory, telecom devices, preservation of information and image quality. Supported by Higher Education Commission (HEC) of Pakistan

  7. Sub-Doppler resonances in the back-scattered light from random porous media infused with Rb vapor

    Villalba, S; Lenci, L; Bloch, D; Lezama, A; Failache, H

    2013-01-01

    We report on the observation of sub-Doppler resonances on the back-scattered light from a random porous glass medium with rubidium vapor filling its interstices. The sub-Doppler spectral lines are the consequence of saturated absorption where the incident laser beam saturates the atomic medium and the back-scattered light probes it. Some specificities of the observed spectra reflect the transient atomic evolution under confinement inside the pores. Simplicity, robustness and potential miniaturization are appealing features of this system as a spectroscopic reference.

  8. The High Spectral Resolution Lidar

    Eloranta, E. W.; Roesler, F. L.; Sroga, J. T.

    1983-01-01

    The High Spectral Resolution Lidar (HSRL) system was developed for the remote measurement of atmospheric optical properties. Measurements are obtained by the separation of the backscattered signal into aerosol and molecular channels using a high spectral resolution Fabry-Perot optical interferometer to separate the aerosol contributions to backscatter near the laser wavelength from the Doppler-shifted molecular component of the backscatter. The transmitter consists of an optically pumped pulsed dye laser of the oscillator-amplifier design which emits at 467.88 nm, with a bandwidth of less than 0.3 pm. The transmitter and receiver share a common Schmidt-Cassegrain telescope, although they do not share the same field stop, but rather two conjugate stops. The HSRL system uses a computer-controlled dual-channel photon-counting data acquisition system providing for stable measurements at very low power levels and an excellent dynamic range. The system has been used to obtain airborne measurements of height profiles of aerosol and molecular backscatter cross sections.

  9. Review Of Parameter Estimation Using Adaptive Filtering

    LALITA RANI, SHALOO KIKAN

    2013-07-01

    Full Text Available In this paper, a comparative study of different adaptive filter algorithm for channel parameter estimation is described. We presented different parameter estimation approaches of adaptive filtering. An extended Kalman filter is then applied as a near-optimal solution to the adaptive channel parameter estimation problem. Kalman filtering is applied for motion parameters resulting in optimal pose estimation. A parallel Kalman filter is applied for joint estimation of code delay, multipath gains and Doppler shift. In this paper, a complete review of parameter estimation using adaptive filtering is explained.

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

    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.

  11. Spectral dimensions from the spectral action

    2014-01-01

    The generalised spectral dimension $D_{ S}(T)$ provides a powerful tool for comparing different approaches to quantum gravity. In this work, we apply this formalism to the classical spectral actions obtained within the framework of almost-commutative geometry. Analysing the propagation of spin-0, spin-1 and spin-2 fields, we show that a non-trivial spectral dimension arises already at the classical level. The effective field theory interpretation of the spectral action yields plateau-structur...

  12. Development of the doppler electron velocimeter: theory.

    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.

  13. Comparison of blood velocity measurements between ultrasound Doppler and accelerated phase-contrast MR angiography in small arteries with disturbed flow

    Jiang Jingfeng; Johnson, Kevin; Wieben, Oliver; Zagzebski, James [Medical Physics Department, University of Wisconsin-Madison School of Medicine and Public Health, WI (United States); Strother, Charles; Consigny, Dan [Radiology Department, University of Wisconsin-Madison School of Medicine and Public Health, WI (United States); Baker, Sara, E-mail: jjiang2@wisc.edu [School of Ultrasound, University of Wisconsin-Madison School of Medicine and Public Health, WI (United States)

    2011-03-21

    Ultrasound Doppler (UD) velocity measurements are commonly used to quantify blood flow velocities in vivo. The aim of our work was to investigate the accuracy of in vivo spectral Doppler measurements of velocity waveforms. Waveforms were derived from spectral Doppler signals and corrected for intrinsic spectral broadening errors by applying a previously published algorithm. The method was tested in a canine aneurysm model by determining velocities in small arteries (3-4 mm diameter) near the aneurysm where there was moderately disturbed flow. Doppler results were compared to velocity measurements in the same arteries acquired with a rapid volumetric phase contrast MR angiography technique named phase contrast vastly undersampled isotropic projection reconstruction magnetic resonance angiography (PC-VIPR MRA). After correcting for intrinsic spectral broadening, there was a high degree of correlation between velocities obtained by the real-time UD and the accelerated PC-MRA technique. The peak systolic velocity yielded a linear correlation coefficient of r = 0.83, end diastolic velocity resulted in r = 0.81, and temporally averaged mean velocity resulted in r = 0.76. The overall velocity waveforms obtained by the two techniques were also highly correlated (r = 0.89 {+-} 0.06). There were, however, only weak correlations for the pulsatility index (PI: 0.25) and resistive index (RI: 0.14) derived from the two techniques. Results demonstrate that to avoid overestimations of peak systolic velocities, the results for UD must be carefully corrected to compensate for errors caused by intrinsic spectral broadening.

  14. Traveling Ionospheric Disturbance Characteristics Over Texas Using the TIDDBIT HF Doppler Radar

    Wene, G.; Crowley, G.; Fessler, B.; Bronn, J.

    2004-05-01

    the costs that would be associated with an incoherent-scatter radar. SwRI recently designed, built and deployed an HF Doppler sounding system for three months, in Texas, to investigate TIDs. The TIDDBIT radar consisted of three transmitters (Austin, Uvalde and St. Hedwig) and a receiver in San Antonio, Texas. Using cross-spectral analysis and triangulation of the TIDDBIT signals, TID speeds and azimuths were obtained for each wave frequency. We provide a synoptic survey of the TID characteristics observed over Texas during January-March 2002. Such a system would be of great utility for the study of gravity wave seeding of low latitude ionospheric irregularities.

  15. Spectral Imaging by Upconversion

    Dam, Jeppe Seidelin; Pedersen, Christian; Tidemand-Lichtenberg, Peter

    We present a method to obtain spectrally resolved images using upconversion. By this method an image is spectrally shifted from one spectral region to another wavelength. Since the process is spectrally sensitive it allows for a tailored spectral response. We believe this will allow standard...... silicon based cameras designed for visible/near infrared radiation to be used for spectral images in the mid infrared. This can lead to much lower costs for such imaging devices, and a better performance....

  16. Microwave Doppler spectra of sea return at small incidence angles: specular point scattering contribution

    It is well known that the sea return echo contains contributions from at least two scattering mechanisms. In addition to the resonant Bragg scattering, the specular point scattering plays an important role as the incidence angle becomes smaller (≤ 20 °). Here, in combination with the Kirchhoff integral equation of scattering field and the stationary phase approximation, analytical expressions for Doppler shift and spectral bandwidth of specular point scattering, which are insensitive to the polarization state, are derived theoretically. For comparison, the simulated results related to the two-scale method (TSM) and the method of moment (MOM) are also presented. It is found that the Doppler shift and the spectral bandwidth given by TSM are insufficient at small incidence angles. However, a comparison between the analytical results and the numerical simulations by MOM in the backscatter configuration shows that our proposed formulas are valid for the specular point scattering case. In this work, the dependences of the predicted results on incidence angle, radar frequency, and wind speed are also discussed. The obtained conclusions seem promising for a better understanding of the Doppler spectra of the specular point scattering fields from time-varying sea surfaces. (classical areas of phenomenology)

  17. Doppler imaging of LQ Hydrae for 1998-2002

    Cole, E. M.; Hackman, T.; Käpylä, M. J.; Ilyin, I.; Kochukhov, O.; Piskunov, N.

    2015-09-01

    Aims: We study the spot distribution on the surface of LQ Hya during the observing seasons October 1998-November 2002. We look for persistent active longitudes, trends in the level of spot activity and compare to photometric data. Methods: We apply the Doppler imaging technique on photospheric spectral lines using an inversion code to retrieve images of the surface temperature. Results: We present new temperature maps using multiple spectral lines for a total of 7 seasons. Conclusions: We find no evidence for active longitudes persisting over multiple observing seasons. The spot activity appears to be concentrated to two latitude regions. Using the currently accepted rotation period, we find spot structures to show a trend in the phase-time plot, indicative of a need for a longer period. We conclude that the long-term activity of LQ Hya is more chaotic than that of some magnetically active binary stars analyzed with similar methods, but still with clear indications of an activity cycle from the photometry. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Table 2 is available in electronic form at http://www.aanda.org

  18. Arm locking with Doppler estimation errors

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

    2010-05-01

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

  19. Diabetic Nephropathy : Evaluation with Doppler Ultrasonography

    Sim, Jung Suk; Kim, Seung Hyup; Kang, Heung Sik; Park, Jae Hyung; Han, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1996-06-15

    To compare Doppler ultrasonography with laboratory tests in evaluation of diabetic nephropathy. Fifty-five patients (mean age = 60, M : F = 26 : 29) with diabetes mellitus underwent renal Doppler ultrasonography. Resistive indices were compared with degree of proteinuria, serum creatinine level, and creatinine clearance rate. Eighteen patients who showed no proteinuria or microscopic proteinuria had a mean resistive index (RI) of 0.72 (SD, 0.05), 16 patients with macroscopic proteinuria without nephrotic syndrome had a mean RI of 0.82 (SD, 0.13), and 21 patients with nephrotic syndrome had a mean RI of 0.90 (SD, 0.12). Renal RI correlated highly with serum creatinine level (r = 0.62) and creatinine clearance rate (r = -0.43). Renal Doppler ultrasonography provides a useful indication of renal function in diabetic nephropathy but cannot offer an advantage over conventional laboratory test

  20. Spectral Decomposition Algorithm (SDA)

    National Aeronautics and Space Administration — Spectral Decomposition Algorithm (SDA) is an unsupervised feature extraction technique similar to PCA that was developed to better distinguish spectral features in...

  1. Gallblader varices in children with portal cavernoma: duplex-Doppler and color Doppler ultrasound studies

    To determine the prevalence of varices in the gallbladder wall, observed by duplex-Doppler and color Doppler ultrasound, in children with cavernoma of the portal vein. Nineteen patients with portal hypertension were studied prospectively by duplex-Doppler and color Doppler ultrasound: 12 of the patients had developed a cavernoma of the portal vein. The presence of peri vesicular varices was assessed in the group of patients with portal cavernoma. Duplex-Doppler and color Doppler ultrasound disclosed the presence of varices in gallbladder wall in nine of the 12 patients (75%). The varices appeared as anechoic and serpiginous areas, and Doppler ultrasound revealed slowed venous flow. However, the three patients in whom gallbldder varices were not detected presented collateral gastric ciculation and spontaneous splenorenal shunt. Gallbladder varices are common in children with portal vein cavernoma; they present hepatopetal flow. Their developments is not related to the size of the portal cavernoma, the presence of spontaneous portosystemic shunts, or endoscopic obliteration of gastric and esophageal varices. The detection of gallbladder varices in patients with portal hypertension who are to undergo biliary surgery is highly important for the surgeon, helping to avoid perioperative complications. (Author) 15 refs

  2. Enhanced Spectral Reflectance Reconstruction Using Pseudo-Inverse Estimation Method

    Ibrahim El-Rifai

    2013-06-01

    Full Text Available This paper will present an enhanced approach for the reconstruction of spectral reflectance by the combination between two methods, the Pseudo-Inverse (PI as the base formula, whilst adaptively selecting the training samples as performed in the Adaptive Wiener estimation method proposed by Shen and Xin for the estimation of the spectral reflectance. This enhancement will be referred to as Adaptive Pseudo-Inverse (API through this research. Training and verification datasets have been prepared from GretagMacbeth ColorChecker CC chart, Kodak Color Chart and a specially designed palette of Japanese organic and inorganic mineral pigments to test and compare the estimation results, using the Pseudo-Inverse and Adaptive Pseudo-Inverse method. The performance of spectral reconstruction methods will be presented in terms of spectral and colorimetric error for the estimation accuracy. The experimental results showed that the proposed method achieved better performance and noticeable decline in spectral estimation error.

  3. Ultrasonographic Doppler Use for Female Reproduction Management.

    Bollwein, Heinrich; Heppelmann, Maike; Lüttgenau, Johannes

    2016-03-01

    Transrectal color Doppler ultrasonography is a useful technique to get new information about physiologic and pathophysiologic alterations of the uterus and ovaries in female cattle. During all reproductive stages characteristic changes in uterine blood flow are observed. Cows with puerperal disturbances show delayed decrease in uterine blood flow in the first few weeks postparturition compared with healthy cows. Measurement of follicular blood flow is used to identify normally developing follicles and predict superovulatory response. Determination of luteal blood is more reliable than B-mode sonography to distinguish between functional and nonfunctional corpora lutea. Color Doppler ultrasonography is a promising tool to improve reproductive management in female cattle. PMID:26922117

  4. Preprocessing of ionospheric echo Doppler spectra

    FANG Liang; ZHAO Zhengyu; WANG Feng; SU Fanfan

    2007-01-01

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

  5. Analisis Efek Doppler pada Sistem Komunikasi ITS-Sat

    Agriniwaty Paulus

    2013-09-01

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

  6. Operational Bright-Band Snow Level Detection Using Doppler Radar

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  7. Fish embryo multimodal imaging by laser Doppler digital holography

    Verrier, Nicolas; Picart, Pascal; Gross, Michel

    2015-01-01

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

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

    McCaffrey, Katherine

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

  9. Evaluation of Portal Venous Velocity with Doppler Ultrasound in Patients with Nonalcoholic Fatty Liver Disease

    We examined the relationship between portal venous velocity and hepatic-abdominal fat in patients with nonalcoholic fatty liver disease (NAFLD), using spectral Doppler ultrasonography (US) and magnetic resonance imaging (MRI). In this prospective study, 35 patients with NAFLD and 29 normal healthy adults (control group) underwent portal Doppler US. The severity of hepatic steatosis in patients with NAFLD was assessed by MRI through chemical shift imaging, using a modification of the Dixon method. Abdominal (intra-abdominal and subcutaneous) fat was measured by MRI. The difference in portal venous velocity between the patients with NAFLD and the control group was significant (p 0.05). There were strong correlations between the hepatic fat fraction and subcutaneous adiposity (p < 0.0001), intraperitoneal fat accumulation (p 0.017), and retroperitoneal fat accumulation (p < 0.0001). Our findings suggest that patients with NAFLD have lower portal venous velocities than normal healthy subjects.

  10. Doppler imaging of the double-lined active binary V824 Ara

    Kriskovics, Levente; Kővári, Zsolt; Garcia-Alvarez, David; Oláh, Katalin

    2013-01-01

    We introduce an iterative spectral disentangling technique combined with Doppler imaging in order to recover surface temperature maps for both components of double-lined active binary systems. Our method provides an opportunity to separate spectra of the active components while minimizing the unwanted disturbances on the given line profile from the other component. The efficiency of the method is demonstrated on real data of the double-lined RS CVn-type binary V824 Ara. The resulting Doppler images reveal cool spots on the polar regions as well as low-latitude features on both of the stars. Moreover, both components have hot spots, that are facing each other. This may indicate interconnection between the stellar magnetic fields.

  11. ABSORPTION PROPERTIES OF A DRIVEN FOUR-LEVEL DOPPLER-BROADENED SYSTEM

    YUAN SHI; WU JIN-HUI; GAO JIN-YUE

    2001-01-01

    This paper deals with the absorption spectra of a weak probe in a four-level Doppler-broadened system driven by three coherent fields. The main aim is to extend earlier studies of the spontaneous emission spectrum and to present a comprehensive survey of the spectral features of this system. In addition to a derivation of exact formulae for the spectra, we give an explanation with the help of an appropriate set of dressed atomic states. We also get a deeper insight into the physical origin of gain in view of the existence of a population inversion between the levels of the lasing transition. Finally, we explore the effect of Doppler broadening on the absorption profile of the weak probe.

  12. Rotational Doppler effect in left-handed materials

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

    2008-01-01

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

  13. Precipitation processes as deduced by combining Doppler radar and disdrometer

    Thomson, Alan Douglas

    Precipitation processes are investigated in stratiform and convective weather systems by combining Doppler radar and disdrometer measurements. Vertical scans are designed to measure the standard radar data fields and the power spectrum of the vertical Doppler velocities with high spatial and temporal resolution. A new method, based on iterative application of a disdrometer-determined Z-R relation, is developed to estimate vertical winds from the vertical scan data. Using this method, radar-based raindrop size spectra calculated near the surface in light stratiform rain compare well with simultaneous measurements from a collocated disdrometer. A full raindrop size spectrum profile is deduced for a specific steady state case. It is found that the spectrum does not vary with height, suggesting that the spectral shape is mainly controlled by the ice particles occurring above the 0oC level. Vertical scan data are also combined with volume scan data obtained by the Atmospheric Environment Service King City radar to examine the precipitation structure of a hail producing region within a severe squall line. The vertical scan shows a large variation in precipitation structure and also reveals important storm features which, in this case, are not detected by the conventional volume scans, such as a weak echo vault, a downdraught outflow, and streaks of very high downward velocity corresponding to separate hail trajectories. The power spectra were used to identify and locate hailstones, to deduce the growth of descending hailstones, and to qualitatively examine properties of raindrop size spectra. A conceptual model of hail formation is proposed by comparing the deduced storm structure and precipitation processes with the analyses of two somewhat similar storms documented in the literature.

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

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

  15. Radar micro-doppler signatures processing and applications

    Chen, Victor C; Miceli, William J

    2014-01-01

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

  16. Applications of doppler effect in navigation and oceanography

    Joseph, A.

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

  17. On acceleration dependence of Doppler effect in light

    Sanjay M Wagh

    2013-09-01

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

  18. Planetary Radio Interferometry and Doppler Experiment (PRIDE) for Planetary Atmospheric Studies

    Bocanegra Bahamon, Tatiana; Cimo, Giuseppe; Duev, Dmitry; Gurvits, Leonid; Molera Calves, Guifre; Pogrebenko, Sergei

    2015-04-01

    The Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a technique that allows the determination of the radial velocity and lateral coordinates of planetary spacecraft with very high accuracy (Duev, 2012). The setup of the experiment consists of several ground stations from the European VLBI Network (EVN) located around the globe, which simultaneously perform Doppler tracking of a spacecraft carrier radio signal, and are subsequently processed in a VLBI-style in phase referencing mode. Because of the accurate examination of the changes in phase and amplitude of the radio signal propagating from the spacecraft to the multiple stations on Earth, the PRIDE technique can be used for several fields of planetary research, among which planetary atmospheric studies, gravimetry and ultra-precise celestial mechanics of planetary systems. In the study at hand the application of this technique for planetary atmospheric investigations is demonstrated. As a test case, radio occultation experiments were conducted with PRIDE having as target ESA's Venus Express, during different observing sessions with multiple ground stations in April 2012 and March 2014. Once each of the stations conducts the observation, the raw data is delivered to the correlation center at the Joint Institute for VLBI in Europe (JIVE) located in the Netherlands. The signals are processed with a high spectral resolution and phase detection software package from which Doppler observables of each station are derived. Subsequently the Doppler corrected signals are correlated to derive the VLBI observables. These two sets of observables are used for precise orbit determination. The reconstructed orbit along with the Doppler observables are used as input for the radio occultation processing software, which consists of mainly two modules, the geometrical optics module and the ray tracing inversion module, from which vertical density profiles, and subsequently, temperature and pressure profiles of Venus

  19. Fifty Years of HF Doppler Observations

    Ogawa, T.; T. Ichinose

    2009-01-01

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

  20. HF Doppler Radar Observations of Geomagnetic Pulsations

    Fišer, Jiří; Chum, Jaroslav

    Prague : Matfyzpress, 2014, s. 304-309. ISBN 978-80-7378-276-4. [Week of Doctoral Students /23./ : focused on physical study branches. Prague (CZ), 03.06.2014-05.06.2014] R&D Projects: GA ČR(CZ) GAP209/12/2440 Institutional support: RVO:68378289 Keywords : Doppler sounding * ionosphere * geomagnetic pulsations Subject RIV: DG - Athmosphere Sciences, Meteorology

  1. Ultrasonic Doppler color in glaucoma: Concordance study

    Our study demonstrates that US color Doppler is a non invasive, reliable and reproducible method for the evaluation of the orbitary flow in normal and glaucomatous patients. However is suggested that every group evaluates the inter and intraobserver variability because of the lack of universal reference velocity measurements

  2. Doppler Shift Compensation Schemes in VANETs

    F. Nyongesa

    2015-01-01

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

  3. The Doppler effect measurement on 238U

    The UO2 sample was irradiated in the RB zero power reactor in order to determine the Doppler effect on the 238 U by measuring the change in the 238 capture cross section with temperature. The measurement was meant to verify the indigenous developed computer codes and nuclear data library

  4. Measurements of the Doppler effect at Phenix

    A measurement of the Doppler effect has been performed at Phenix. Large corrections were necessary. Thus the measurement has been done again on another way. Results agree. A comparison has been made with the results of a theoretical calculation performed with the CARNAVAL IV ''formulaire''

  5. Method for Canceling Ionospheric Doppler Effect

    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.

  6. Measurement of TID and Gravity Wave Parameters Using An HF Doppler System

    Wene, G. P.; Crowley, G.; Fessler, B. W.; Bronn, J. S.

    2005-05-01

    The manifestation of atmospheric gravity waves (AGWs) in the ionosphere is called a traveling ionospheric disturbance (TID). TIDs can be thought of as traveling corrugations in the ionosphere, and as such can seriously affect HF radio communications and surveillance systems. They may indirectly play a greater role in disrupting communications by triggering the growth of ionospheric instabilities, resulting in scintillation of radio signals. It is therefore of great interest to monitor TIDs on a routine basis, and to correlate their properties with other phenomena. In this paper, we present data from a unique radio technique for measuring TID properties such as their spectrum, and their spectrally resolved propagation characteristics. 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. 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 the costs that would be associated with an incoherent-scatter radar. SwRI recently designed, built and deployed an HF Doppler sounding system in Texas, to investigate TIDs. The TIDDBIT radar consisted of three transmitters (Austin, Uvalde and St. Hedwig) and a receiver in San Antonio, Texas. Using a cross-spectral analysis technique, TID speeds and azimuths were obtained for each wave frequency. We provide a synoptic survey of the TID characteristics observed over Texas during January-March 2002. The Doppler system provides an accurate

  7. Successive Spectral Sequences

    Matschke, Benjamin

    2013-01-01

    If a chain complex is filtered over a poset I, then for every chain in I we obtain a spectral sequence. In this paper we define a spectral system that contains all these spectral sequences and relates their pages via differentials, extensions, and natural isomorphisms. We also study an analog of exact couples that provides a more general construction method for these spectral systems. This turns out to be a good framework for unifying several spectral sequences that one would usually apply on...

  8. On golden spectral graphs

    Estrada Roger, Ernesto; Gago Álvarez, Silvia

    2009-01-01

    The concept of golden spectral graphs is introduced and some of their general properties reported. Golden spectral graphs are those having a golden proportion for the spectral ratios defined on the basis of the spectral gap, spectral spread and the difference between the second largest and the smallest eigenvalue of the adjacency matrix. They are good expanders and display excellent synchronizability. Here we report some new construction methods as well as several of their topological pa...

  9. Doppler speedometer for micro-organisms

    Objective of Investigations: Development and creation of the Doppler speedometer for micro-organisms which allows to evaluate, in a real temporal scale, variations in the state of water suspension of micro-organisms under the effect of chemical, physical and other external actions. Statement of the Problem The main problem is absence of reliable, accessible for users and simple, in view of application, Doppler speedometers for micro-organisms. Nevertheless, correlation Doppler spectrometry in the regime of heterodyning the supporting and cell-scattered laser radiation is welt known. The main idea is that the correlation function of photo-current pulses bears an information on the averages over the assembly of cell velocities. For solving the biological problems, construction of auto-correlation function in the real-time regime with the delay time values comprising, function in the real-time regime with the delay time values comprising, nearly, 100 me (10 khz) or higher is needed. Computers of high class manage this problem using but the program software. Due to this, one can simplify applications of the proposed techniques provided he creates the Doppler speedometer for micro-organism on a base of the Pentium. Expected Result Manufactured operable mock-up of the Doppler speedometer for micro-organisms in a form of the auxiliary computer block which allows to receive an information, in the real time scale, on the results of external effects of various nature on the cell assembly in transparent medium with a small volume of the studied cell suspension

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

    Smallwood, R. H.; Dixon, P.

    1986-03-01

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

  11. On the Spectral Singularities and Spectrality of the Hill Operator

    O. A. Veliev

    2014-01-01

    First we study the spectral singularity at infinity and investigate the connections of the spectral singularities and the spectrality of the Hill operator. Then we consider the spectral expansion when there is not the spectral singularity at infinity.

  12. Characterization of very narrow spectral lines with temporal intensity interferometry

    Tan, Peng Kian

    2016-01-01

    Context: Some stellar objects exhibit very narrow spectral lines in the visible range additional to their blackbody radiation. Natural lasing has been suggested as a mechanism to explain narrow lines in Wolf-Rayet stars. However, the spectral resolution of conventional astronomical spectrographs is still about two orders of magnitude too low to test this hypothesis. Aims: We want to resolve the linewidth of narrow spectral emissions in starlight. Methods: A combination of spectral filtering with single-photon-level temporal correlation measurements breaks the resolution limit of wavelength-dispersing spectrographs by moving the linewidth measurement into the time domain. Results: We demonstrate in a laboratory experiment that temporal intensity interferometry can determine a 20 MHz wide linewidth of Doppler-broadened laser light, and identify a coherent laser light contribution in a blackbody radiation background.

  13. The Spectral Shift Function and Spectral Flow

    Azamov, N. A.; Carey, A. L.; Sukochev, F. A.

    2007-11-01

    At the 1974 International Congress, I. M. Singer proposed that eta invariants and hence spectral flow should be thought of as the integral of a one form. In the intervening years this idea has lead to many interesting developments in the study of both eta invariants and spectral flow. Using ideas of [24] Singer’s proposal was brought to an advanced level in [16] where a very general formula for spectral flow as the integral of a one form was produced in the framework of noncommutative geometry. This formula can be used for computing spectral flow in a general semifinite von Neumann algebra as described and reviewed in [5]. In the present paper we take the analytic approach to spectral flow much further by giving a large family of formulae for spectral flow between a pair of unbounded self-adjoint operators D and D + V with D having compact resolvent belonging to a general semifinite von Neumann algebra {mathcal{N}} and the perturbation V in {mathcal{N}} . In noncommutative geometry terms we remove summability hypotheses. This level of generality is made possible by introducing a new idea from [3]. There it was observed that M. G. Krein’s spectral shift function (in certain restricted cases with V trace class) computes spectral flow. The present paper extends Krein’s theory to the setting of semifinite spectral triples where D has compact resolvent belonging to {mathcal{N}} and V is any bounded self-adjoint operator in {mathcal{N}} . We give a definition of the spectral shift function under these hypotheses and show that it computes spectral flow. This is made possible by the understanding discovered in the present paper of the interplay between spectral shift function theory and the analytic theory of spectral flow. It is this interplay that enables us to take Singer’s idea much further to create a large class of one forms whose integrals calculate spectral flow. These advances depend critically on a new approach to the calculus of functions of non

  14. Doppler Imaging with a Clean-Like Approach - Part One - a Newly Developed Algorithm Simulations and Tests

    Kurster, M.

    1993-07-01

    A newly developed method for the Doppler imaging of star spot distributions on active late-type stars is presented. It comprises an algorithm particularly adapted to the (discrete) Doppler imaging problem (including eclipses) and is very efficient in determining the positions and shapes of star spots. A variety of tests demonstrates the capabilities as well as the limitations of the method by investigating the effects that uncertainties in various stellar parameters have on the image reconstruction. Any systematic errors within the reconstructed image are found to be a result of the ill-posed nature of the Doppler imaging problem and not a consequence of the adopted approach. The largest uncertainties are found with respect to the dynamical range of the image (brightness or temperature contrast). This kind of uncertainty is of little effect for studies of star spot migrations with the objectives of determining differential rotation and butterfly diagrams for late-type stars.

  15. Power and color Doppler ultrasound settings for inflammatory flow

    Torp-Pedersen, Søren; Christensen, Robin; Szkudlarek, Marcin;

    2015-01-01

    OBJECTIVE: To determine how settings for power and color Doppler ultrasound sensitivity vary on different high- and intermediate-range ultrasound machines and to evaluate the impact of these changes on Doppler scoring of inflamed joints. METHODS: Six different types of ultrasound machines were used....... On each machine, the factory setting for superficial musculoskeletal scanning was used unchanged for both color and power Doppler modalities. The settings were then adjusted for increased Doppler sensitivity, and these settings were designated study settings. Eleven patients with rheumatoid arthritis...... (RA) with wrist involvement were scanned on the 6 machines, each with 4 settings, generating 264 Doppler images for scoring and color quantification. Doppler sensitivity was measured with a quantitative assessment of Doppler activity: color fraction. Higher color fraction indicated higher sensitivity...

  16. ESTIMATION OF DOPPLER CENTROID FREQUENCY IN SPACEBORNE SCANSAR

    2008-01-01

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

  17. Spectral shearing of quantum light pulses by electro-optic phase modulation

    Wright, Laura J.; Karpinski, Michal; Soeller, Christoph; Smith, Brian J.

    2016-01-01

    Frequency conversion of non-classical light enables robust encoding of quantum information based upon spectral multiplexing that is particularly well-suited to integrated-optics platforms. Here we present an intrinsically deterministic linear-optics approach to spectral shearing of quantum light pulses and show it preserves the wave-packet coherence and quantum nature of light. The technique is based upon an electro-optic Doppler shift to implement frequency shear of heralded single-photon wa...

  18. Statistical study of high-latitude E-region Doppler spectra obtained with the SHERPA HF radar

    Hanuise, C.; Villain, J. P.; Cerisier, J. C.; Senior, C.; Ruohoniemi, J. M.; Greenwald, R. A.; Baker, K. B.

    1991-04-01

    A large number of Doppler spectra obtained at six HF frequencies in the E region with the SHERPA HF radar are analyzed statistically. They are characterized by their total power, their mean velocity and their spectral width. The observations cover geomagnetic conditions varying from quiet to disturbed. Due to the location of the auroral oval relative to the radar field of view, echoes are preferentially detected in the morning westward electrojet, with radial velocities away from the radar. This results in an asymmetrical velocity distribution. Both usual Type 1 and Type 2 Doppler spectra, associated with two-stream and gradient-drift waves, respectively, are at the origin of the two peaks in the distribution. Other spectral types do not appear in the statistics. Spectral widths remain narrow for both types. This is explained by a longer lifetime of wave trains compared to higher frequency waves detected by VHF radars. A decrease of the Doppler velocity with radar frequency is related to gradient effects on threshold, as predicted by the linear dispersion equation for the two-stream instability.

  19. Doppler Tomography of XTE J2123-058 and Other Neutron Star LMXBs

    Hynes, R I; Haswell, C A; Casares, J; Zurita, C

    2000-01-01

    We describe Doppler tomography obtained in the 1998 outburst of the neutron star low mass X-ray binary (LMXB) XTE J2123-058. This analysis, and other aspects of phase-resolved spectroscopy, indicate similarities to SW Sex systems, except that anomalous emission kinematics are seen in HeII, whilst phase 0.5 absorption is confined to H alpha. This separation of these effects may provide tighter constraints on models in the LMXB case than is possible for SW Sex systems. We will compare results for other LMXBs which appear to show similar kinematics and discuss how models for the SW Sex phenomenon can be adapted to these systems. Finally we will summarise the limited Doppler tomography performed on the class of neutron star LMXBs as a whole, and discuss whether any common patterns can yet be identified.

  20. Measurement of velocities in noisy environments with a microwave Doppler-effect radar

    An undergraduate experiment is proposed to facilitate the understanding of the basic principles related to radar systems and signal analysis. A Doppler-effect radar has been installed and used to measure the velocities of a target under different conditions. This system features the use of a low-power generator and a general purpose data acquisition card. The analysis of the measured IF (intermediate frequency) voltage has been made by using the fast Fourier transform in order to illustrate the relevance of the basic spectral techniques for the characterization of weak signals in noisy environments. (author)

  1. Doppler-free two-photon absorption spectroscopy of rovibronic transition of naphthalene calibrated with an optical frequency comb

    Nishiyama, A.; Nakashima, K.; Matsuba, A.; Misono, M.

    2015-12-01

    We performed Doppler-free two-photon absorption spectroscopy of naphthalene using an optical frequency comb as a frequency reference. Rotationally resolved rovibronic spectra were observed, and absolute frequencies of the rovibronic transitions were determined with an uncertainty of several tens of kHz. The resolution and precision of our system are finer than the natural width of naphthalene. We assigned 1466 lines of the Q (Ka) Q (J) transition and calculated molecular constants. We attribute systematic spectral line shifts to the Coriolis interaction, and discuss the origin of the spectral linewidths.

  2. Color Doppler US of the penis

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

    2008-07-01

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

  3. Minior Actinide Doppler Coefficient Measurement Assessment

    Nolan E. Hertel; Dwayne Blaylock

    2008-04-10

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

  4. Laser Doppler measurement of cutaneous blood flow

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

  5. Transcranial Doppler sonography in familial hemiplegic migraine

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

  6. Color Doppler US of the penis

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

  7. Design of a Doppler reflectometer for KSTAR

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

    2014-11-15

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

  8. Renal duplex Doppler ultrasound findings in diabetics

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

  9. Single mode, extreme precision Doppler spectrographs

    Schwab, Christian; Leon-Saval, Sergio G.; Betters, Christopher H.; Bland-Hawthorn, Joss; Mahadevan, Suvrath

    2012-01-01

    The 'holy grail' of exoplanet research today is the detection of an earth-like planet: a rocky planet in the habitable zone around a main-sequence star. Extremely precise Doppler spectroscopy is an indispensable tool to find and characterize earth-like planets; however, to find these planets around solar-type stars, we need nearly one order of magnitude better radial velocity (RV) precision than the best current spectrographs provide. Recent developments in astrophotonics (Bland-Hawthorn & Ho...

  10. Doppler Lidar Wind Value-Added Product

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

    2015-07-01

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

  11. Doppler Findings in Intrapartum Fetal Distress

    Khatereh Tooba; Laleh Eslamian

    2011-01-01

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

  12. El doppler en podología

    Albiol Ferrer, Josep Maria; Giralt de Veciana, Enrique; Hernández Galayo, Fco. Javier (Francisco Javier); Novel Martí, Virginia; Padrós Sánchez, Carolina; Valero, L.

    1990-01-01

    El sistema doppler por ultrasonido es un método de exploración incruento y no invasivo, que permite tener acceso a los fenómenos hemodinamicos producido en el interior de los vasos. Es un sistema de relativa sencillez de manejo, pero que utilizado correelamente aporta datos fidedignos de la velocidad del flujo como del estado de la pared de los vasos.

  13. Sub-Nyquist Radar via Doppler Focusing

    Bar-Ilan, Omer; Eldar, Yonina C.

    2012-01-01

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

  14. Color Doppler imaging of cervicocephalic fibromuscular dysplasia

    Grzyska Ulrich; Arning Christian

    2004-01-01

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

  15. Poincare's relativistic Doppler-Fizeau formula

    Pierseaux, Yves

    2006-01-01

    We deduce from Poincare's ellipsoidal wavefronts a relativistic Doppler-Fizeau formula that is not the same as 1905 Einstein's one. Longitudinally, Einstein's formula and Poincare's formula are the same. The question of an experimental test is connected with the possibility or the impossibility of directly measuring the relativistic transverse effect. Hasselkamp's 1978 experiment becomes a crucial experiment because Poincare's relativistic kinematics predicts an expansion of sapce directly co...

  16. Doppler-free magnetic optical activity

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

    1980-01-01

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

  17. Doppler cooling to the Quantum limit

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

    2011-01-01

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

  18. Adaptive Lighting

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive LightingAdaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled i...

  19. Doppler Lidar for Wind Measurements on Venus

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

    2010-01-01

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

  20. COLOUR DOPPLER EVALUATION OF ACUTE RENAL COLIC

    Vallepu Ramaiah

    2016-05-01

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

  1. Precise Doppler Monitoring of Barnard's Star

    Choi, Jieun; Marcy, Geoffrey W; Howard, Andrew W; Fischer, Debra A; Johnson, John A; Isaacson, Howard; Wright, Jason T

    2012-01-01

    We present 248 precise Doppler measurements of Barnard's Star (Gl 699), the second nearest star system to Earth, obtained from Lick and Keck Observatories during 25 years between 1987 and 2012. The early precision was 20 \\ms{} but was 2 \\ms{} during the last 8 years, constituting the most extensive and sensitive search for Doppler signatures of planets around this stellar neighbor. We carefully analyze the 136 Keck radial velocities spanning 8 years by first applying a periodogram analysis to search for nearly circular orbits. We find no significant periodic Doppler signals with amplitudes above $\\sim$2 \\ms{}, setting firm upper limits on the minimum mass (\\msini) of any planets with orbital periods from 0.1 to 1000 days. Using a Monte Carlo analysis for circular orbits, we determine that planetary companions to Barnard's Star with masses above 2 \\mearth{} and periods below 10 days would have been detected. Planets with periods up to 2 years and masses above 10 \\mearth{} (0.03 \\mjup) are also ruled out. A sim...

  2. The Modulation of Ionospheric Alfven Resonator on Heating HF Waves and the Doppler Effect

    NiBin-bin; ZhaoZheng-yu; XieShu-guo

    2003-01-01

    The propagation of HF waves in IAR can produce many nonlinear effects, including the modulation effect of IAR on HF waves and the Doppler effect. To start with the dependence of the ionospheric electron temperature varia-tions on the Alfven resonant field, We discuss the mechanism of the modulation effect and lucubrate possible reasons for the Doppler effect. The results show that the Alfven resonant field can have an observable modulation effect on HF waves while its mechanism is quite different from that of Schumann resonant field on HF waves. The depth of modulation of IAR on HF waves has a quasi-quadratic relation with the Alfven field, which directly inspires the formation of cross-spectrum between ULF waves and HF waves and results in spectral peaks at some gyro-frequencies of IAR. With respect to the Doppler effect during the propagation of HF waves in IAR, it is mainly caused by the motion of the high-speed flyer and the drifting electrons and the frequency shift from the phase vari-ation of the reflected waves can be neglected when the frequency of HF incident wave is high enough.

  3. Transcranial doppler: Technique and common findings (Part 1

    Lokesh Bathala

    2013-01-01

    Full Text Available Transcranial Doppler (TCD can be aptly called as the doctor′s stethoscope of the brain. Since its introduction in 1982, by Rune Aaslid, TCD has evolved as a diagnostic, monitoring, and therapeutic tool. During evaluation of patients with acute ischemic stroke, TCD combined with cervical duplex ultrasonography provides physiological information on the cerebral hemodynamics, which is often complementary to structural imaging. Currently, TCD is the only diagnostic tool that can provide real time information about cerebral hemodynamics and can detect embolization to the cerebral vessels. TCD is a noninvasive, cost-effective, and bedside tool for obtaining information regarding the collateral flow across various branches of the circle of Willis in patients with cerebrovascular disorders. Advanced applications of TCD help in the detection of right-to-left shunts, vasomotor reactivity, diagnosis, and monitoring of vasospasm in subarachnoid hemorrhage and as a supplementary test for confirmation of brain death. This article describes the basic ultrasound physics pertaining to TCD insonation methods, for detecting the flow in intracranial vessels in addition to the normal and abnormal spectral flow patterns.

  4. Realistic Prediction of BER for Adaptive OFDM Systems

    Luo, Meiling; Villemaud, Guillaume; Gorce, Jean-Marie; Jie ZHANG

    2013-01-01

    Adaptive OFDM systems improve the spectral efficiency. In this paper, block adaptive modulation is implemented based on the realistic prediction of BER and fading parameters from the MR-FDPF model. The aggregate data rate from block adaptive modulation is compared to that from non-adaptive modulation, and at the end, the data rate gain is obtained.

  5. Zeta Spectral Action

    Kurkov, Maxim A; Sakellariadou, Mairi; Watcharangkool, Apimook

    2014-01-01

    In this paper we propose a novel definition of the bosonic spectral action using zeta function regularization, in order to address the issues of renormalizability, ultraviolet completeness and spectral dimensions. We compare the zeta spectral action with the usual (cutoff based) spectral action and discuss its purely spectral origin, predictive power, stressing the importance of the issue of the three dimensionful fundamental constants, namely the cosmological constant, the Higgs vacuum expectation value, and the gravitational constant. We emphasize the fundamental role of the neutrino Majorana mass term for the structure of the bosonic action.

  6. Design and Calibration of Autonomous Coherent Doppler Lidar for Space Missions

    Frehlich, Rod G.; Kavaya, Michael (Technical Monitor)

    2001-01-01

    Developed a new algorithm for the simulation of three dimensional homogeneous turbulent velocity fields. For typical atmospheric conditions it is impossible to produce a simulated velocity field that simultaneously satisfy a given spatial correlation and the corresponding spatial spectrum because of spectral aliasing. The new algorithms produce a turbulent velocity field which has accurate spatial correlations which is required for performance predictions from space-based systems. Developed a new algorithm for extracting the spatial statistics of the atmospheric velocity field using coherent Doppler lidar. The performance of the algorithm was compared with past methods and the new algorithm produces useful results for space-based data, which was not possible before. Developed new methods for verification of the errors in ground-based and space-based Doppler lidar wind measurements. These new methods do not require independent in situ data. This is an important issue for the verification of space-based Doppler lidar measurements of the global wind field. The performance of the new algorithm was compared with past results for both space-based and ground-based operation. The new algorithm has the best performance and is the only algorithm that performed satisfactory for spacebased operation. The performance of coherent Doppler lidar for a space missions with various scanning geometries was determined using computer simulation which contained the effects of random instrumental velocity errors, wind shear, wind variability along the range-gate and from shot-to-shot, and random variations in atmospheric aerosol backscatter over the measurement volume. The bias in the velocity estimates was small and the accuracy in the is typically less than 0.5 m/s for high signal conditions. For a large number of shot per velocity estimate, the threshold signal level for acceptable estimates is proportional to the number of shots to the minus one half power. This agrees with previous

  7. Recommendations for terminology and display for doppler echocardiography

    Doppler echocardiography has recently emerged as a major noninvasive technique with many applications in cardiology. To a large extent, this has been based upon a combination of clinical and engineering advances which now make possible the use of quantitative Doppler echocardiography in combination with two-dimensional imaging for measurement of volume flows, transvalve gradients, and other physiologic flow parameters which reflect cardiac function. It was the purpose of this Committee to provide a glossary of terms which could be used in standard fashion for papers and discussions related to Doppler echocardiography. As part of its task, the Committee also undertook an attempt to recommend a standard for display of Doppler information which would be useful, both for manufacturers and for clinicians. The document, therefore, includes: Section I, the Committee's recommendations for Doppler display. Section II, the glossary of Doppler terms, related to engineering and to clinical applications

  8. Planet Candidate Validation and Spin-Orbit Misalignments from Doppler Tomography

    Johnson, Marshall C.

    2016-01-01

    Short-period planets around intermediate-mass (~1.5-2.5 M⊙ A-mid F type) stars are a largely unexplored region of parameter space. These stars' typically rapid rotation and rotationally broadened spectral lines preclude the use of the precise radial velocity measurements that are typically used to discover planets and confirm transiting planet candidates. Nonetheless, exploring this population is important for constraining models of planet formation and migration. I have been using Doppler tomography to investigate this population. As a planet transits a rotating star, it successively obscures regions of the stellar disk with different radial velocities, resulting in a perturbation to the rotationally broadened line profile; this is the Rossiter-McLaughlin effect. In Doppler tomography, I spectroscopically resolve this perturbation and its movement during the transit. This allows me to not only validate transiting planet candidates, as I can show that the transiting object orbits the target star and is not a blended background eclipsing binary, but also to measure the spin-orbit misalignments of these planets. This is the (sky-projected) angle between the stellar spin and planetary orbital angular momentum vectors, and is a statistical probe of planetary migration; different migration mechanisms predict different distributions of spin-orbit misalignments. In this dissertation talk I will discuss my work to validate Kepler planet candidates around rapidly rotating stars using Doppler tomography, and to measure the spin-orbit misalignments of hot Jupiters discovered by ground-based surveys. I will also discuss the use of Doppler tomography to provide additional characterization of planets and their host stars, such as the detection of planetary orbital precession and stellar differential rotation. Finally, I will highlight the potential of current and future missions such as K2 and TESS to expand our knowledge of planets around intermediate-mass stars.

  9. A portable CW/FM-CW Doppler radar for local investigation of severe storms

    Unruh, Wesley P.; Wolf, Michael A.; Bluestein, Howard B.

    During the 1987 spring storm season we used a portable 1-W X-band CW Doppler radar to probe a tornado, a funnel cloud, and a wall cloud in Oklahoma and Texas. This same device was used during the spring storm season in 1988 to probe a wall cloud in Texas. The radar was battery powered and highly portable, and thus convenient to deploy from our chase vehicle. The device separated the receding and approaching Doppler velocities in real time and, while the radar was being used, it allowed convenient stereo data recording for later spectral analysis and operator monitoring of the Doppler signals in stereo headphones. This aural monitoring, coupled with the ease with which an operator can be trained to recognize the nature of the signals heard, made the radar very easy to operate reliably and significantly enhanced the quality of the data being recorded. At the end of the 1988 spring season, the radar was modified to include FM-CW ranging and processing. These modifications were based on a unique combination of video recording and FM chirp generation, which incorporated a video camera and recorder as an integral part of the radar. After modification, the radar retains its convenient portability and the operational advantage of being able to listen to the Doppler signals directly. The original mechanical design was unaffected by these additions. During the summer of 1988, this modified device was used at the Langmuir Laboratory at Socorro, New Mexico in an attempt to measure vertical convective flow in a thunderstorm.

  10. Adaptive blood velocity estimation in medical ultrasound

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2007-01-01

    This paper investigates the use of data-adaptive spectral estimation techniques for blood velocity estimation in medical ultrasound. Current commercial systems are based on the averaged periodogram, which requires a large observation window to give sufficient spectral resolution. Herein, we propose...

  11. Spacecraft Doppler Tracking as a Xylophone Detector of Gravitational Radiation

    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.

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

    D. Altadill; Bianchi, C

    2005-01-01

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

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

    Zhou, Hailong; Zhang, Pei; Zhang, Xinliang

    2015-01-01

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

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

    XU Jia; JIANG Xingzhou; TANG Jingsong

    2003-01-01

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

  15. Doplerovi brodski navigacioni brzinomjeri / Maritime navigational Doppler logs

    Milovan Unković

    2006-01-01

    Doplerovi navigacioni brodski brzinomjeri rade na principu Doplerovog efekta. Doplerov predajni projektor emituje snop ultrazvučnih vibracija u vodi, a drugi (ili isti) projektor prima odbijeni signal od dna ili od sloja vode. U ovom radu opisana je teorija Doplerovog efekta, primjena te teorije na brodskim brzinomjerima, konstrukcija i karakteristike savremenih Doplerovih brzinomjera. / The Doppler maritime navigational logs are based on measurement of the Doppler effect. A Doppler log trans...

  16. Minimally destructive, Doppler measurement of a quantized, superfluid flow

    Kumar, A.; Anderson, N.; Phillips, W. D.; Eckel, S.; Campbell, G. K.; Stringari, S.

    2015-01-01

    The Doppler effect, the shift in the frequency of sound due to motion, is present in both classical gases and quantum superfluids. Here, we perform an in-situ, minimally destructive measurement, of the persistent current in a ring-shaped, superfluid Bose-Einstein condensate using the Doppler effect. Phonon modes generated in this condensate have their frequencies Doppler shifted by a persistent current. This frequency shift will cause a standing-wave phonon mode to be "dragged" along with the...

  17. Interpretation of Doppler blood flow velocity waveforms using neural networks.

    Baykal, N; Reggia, J. A.; Yalabik, N.; Erkmen, A.; Beksac, M. S.

    1994-01-01

    Doppler umbilical artery blood flow velocity waveform measurement is used in perinatal surveillance for the evaluation of pregnancy status. There is an ongoing debate on the predictive value of Doppler measurements concerning the critical effect of the selection of parameters for the evaluation of Doppler output. In this paper, we describe how neural network methods can be used both to discover relevant classification features and subsequently to classify patients. Classification accuracy var...

  18. Doppler-like effect and doubtful expansion of universe

    Szaraniec, Edward

    2003-01-01

    The distance contraction, as observed in electrical soundings over horizontally stratified earth (static system), is identified as a counterpart of Doppler shift in dynamical systems. Identification of Doppler-like effect in a stock-still systems makes it possible to give an al-ternative answer to the question about an effective cause of the Doppler shift, which sounds: the inhomogeneities. This answer opens different static as well as kinematic possibilities, which challenge established theo...

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

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

    2015-01-01

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

  20. Adapting photosynthesis to the near-infrared: non-covalent binding of phycocyanobilin provides an extreme spectral red-shift to phycobilisome core-membrane linker from Synechococcus sp. PCC7335.

    Miao, Dan; Ding, Wen-Long; Zhao, Bao-Qing; Lu, Lu; Xu, Qian-Zhao; Scheer, Hugo; Zhao, Kai-Hong

    2016-06-01

    Phycobiliproteins that bind bilins are organized as light-harvesting complexes, phycobilisomes, in cyanobacteria and red algae. The harvested light energy is funneled to reaction centers via two energy traps, allophycocyanin B and the core-membrane linker, ApcE1 (conventional ApcE). The covalently bound phycocyanobilin (PCB) of ApcE1 absorbs near 660nm and fluoresces near 675nm. In cyanobacteria capable of near infrared photoacclimation, such as Synechococcus sp. PCC7335, there exist even further spectrally red shifted components absorbing >700nm and fluorescing >710nm. We expressed the chromophore domain of the extra core-membrane linker from Synechococcus sp. PCC7335, ApcE2, in E. coli together with enzymes generating the chromophore, PCB. The resulting chromoproteins, PCB-ApcE2(1-273) and the more truncated PCB-ApcE2(24-245), absorb at 700nm and fluoresce at 714nm. The red shift of ~40nm compared with canonical ApcE1 results from non-covalent binding of the chromophore by which its full conjugation length including the Δ3,3(1) double bond is preserved. The extreme spectral red-shift could not be ascribed to exciton coupling: dimeric PCB-ApcE2(1-273) and monomeric-ApcE2(24-245) absorbed and fluoresced similarly. Chromophorylation of ApcE2 with phycoerythrobilin- or phytochromobilin resulted in similar red shifts (absorption at 615 and 711nm, fluorescence at 628 or 726nm, respectively), compared to the covalently bound chromophores. The self-assembled non-covalent chromophorylation demonstrates a novel access to red and near-infrared emitting fluorophores. Brightly fluorescent biomarking was exemplified in E. coli by single-plasmid transformation. PMID:27045046

  1. Adaptive skills

    Staša Stropnik; Jana Kodrič

    2013-01-01

    Adaptive skills are defined as a collection of conceptual, social and practical skills that are learned by people in order to function in their everyday lives. They include an individual's ability to adapt to and manage her or his surroundings to effectively function and meet social or community expectations. Good adaptive skills promote individual's independence in different environments, whereas poorly developed adaptive skills are connected to individual's dependency and with g...

  2. Angular distributions by the conventional and the Doppler shift method

    The angular distribution of elastically scattered metastable Ne*(3P2) has been measured by the conventional and the Doppler shift method. The conventional method shows a good angular resolution and signal to noise ratio. For the Doppler shift method, the angular resolution and the signal to noise ratio are much worse. By Monte Carlo-calculations it is shown that the influence of the residual velocity profiles of the supersonic atomic beams is large for the Doppler method, but can nearly be neglected for the conventional method. For nonsymmetric systems (such as Na2-Xe) and for inelastic processes the Doppler method is expected to be more successful. (Auth.)

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

    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.

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

    Luca Giugno

    2007-05-01

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

  5. Kinematic Seismic Rupture Parameters from a Doppler Analysis

    Caldeira, Bento; Bezzeghoud, Mourad; Borges, José F.

    2010-05-01

    The radiation emitted from extended seismic sources, mainly when the rupture spreads in preferred directions, presents spectral deviations as a function of the observation location. This aspect, unobserved to point sources, and named as directivity, are manifested by an increase in the frequency and amplitude of seismic waves when the rupture occurs in the direction of the seismic station and a decrease in the frequency and amplitude if it occurs in the opposite direction. The model of directivity that supports the method is a Doppler analysis based on a kinematic source model of rupture and wave propagation through a structural medium with spherical symmetry [1]. A unilateral rupture can be viewed as a sequence of shocks produced along certain paths on the fault. According this model, the seismic record at any point on the Earth's surface contains a signature of the rupture process that originated the recorded waveform. Calculating the rupture direction and velocity by a general Doppler equation, - the goal of this work - using a dataset of common time-delays read from waveforms recorded at different distances around the epicenter, requires the normalization of measures to a standard value of slowness. This normalization involves a non-linear inversion that we solve numerically using an iterative least-squares approach. The evaluation of the performance of this technique was done through a set of synthetic and real applications. We present the application of the method at four real case studies, the following earthquakes: Arequipa, Peru (Mw = 8.4, June 23, 2001); Denali, AK, USA (Mw = 7.8; November 3, 2002); Zemmouri-Boumerdes, Algeria (Mw = 6.8, May 21, 2003); and Sumatra, Indonesia (Mw = 9.3, December 26, 2004). The results obtained from the dataset of the four earthquakes agreed, in general, with the values presented by other authors using different methods and data. [1] Caldeira B., Bezzeghoud M, Borges JF, 2009; DIRDOP: a directivity approach to determining

  6. Current-induced spin wave Doppler shift

    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. Applications of Doppler optical coherence tomography

    Xu, Zhiqiang

    A major development in biomedical imaging in the last decade has been optical coherence tomography (OCT). This technique enables microscale resolution, depth resolved imaging of the detailed morphology of transparent and nontransparent biological tissue in a noncontact and quasi-noninvasive way. In the first part of this dissertation, we will describe the development and the performance of our home-made OCT systems working with different wavelength regions based on free-space and optical fiber Michelson interferometers. The second part will focus on Doppler OCT (DOCT), an important extension of OCT, which enables the simultaneous evaluation of the structural information and of the fluid flow distribution at a localized position beneath the sample surface. Much effort has been spent during the past few years in our laboratory aimed at providing more accurate velocity measurements with an extended dynamic range. We also applied our technique in different research areas such as microfluidics and hemodynamics. Investigations on the optical properties of the biological tissues (such as absorption and scattering) corresponding to different center wavelengths, have been performed in our laboratory. We used a 10 femtosecond Ti:sapphire laser centered at about 810 nm associated with a free-space Michelson interferometer. The infrared sources were centered at about 1310 and 1560 nm with all-fiber interferometers. Comparative studies using three different sources for several in vitro biological tissues based on a graphical method illustrated how the optical properties affect the quality of the OCT images in terms of the penetration depth and backscattering intensity. We have shown the advantage of working with 810-nm emission wavelength for good backscattering amplitude and contrast, while sources emitting at 1570 nm give good penetration depth. The 1330-nm sources provide a good compromise between the two. Therefore, the choice of the source will ultimately determine the

  8. Coherent Detection in Laser Doppler Velocimeters

    Hanson, Steen Grüner

    1974-01-01

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

  9. Transmission media effects on precise Doppler tracking

    Callahan, P. S.

    1978-01-01

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

  10. Moessbauer spectroscopy - applications of the Doppler principle

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

  11. Doppler cooling to the quantum limit.

    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

  12. Doppler cooling and trapping on forbidden transitions

    Binnewies, T.; Wilpers, G.; Sterr, U.; Riehle, F.; Helmcke, J.; Mehlstäubler, T. E.; Rasel, E. M.; Ertmer, W.

    2001-01-01

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of ^40Ca atoms has been cooled and trapped to a temperature as low as 6 \\mu K by operating a magneto-optical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method more than 1...

  13. Doppler cooling to the Quantum limit

    Chalony, Maryvonne; Klappauf, Bruce; Wilkowski, David

    2011-01-01

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

  14. Ionospheric variations in the period range of days to tens of days deduced from HF doppler observation

    The HF Doppler frequency variation of the ionosphere corresponds to ionospheric phase path change, which should be ascribed to traveling ionospheric disturbance, solar flares (UV and X-ray), magnetic pulsation, geomagnetic sudden commencement as well as sudden impulse. Therefore, the HF Doppler variation may possibly be a manifestation of solar-terrestrial activity. In this paper, the results of the spectral analysis of ionospheric variation in the period ranging from a few days to tens of days observed by the HFD method in nearly the whole year of 1986 are reported. For the purpose of comparison, the spectral analysis has been done on the of F2 data and the horizontal component data of the geomagnetic field, which were obtained during the same observation period. The present study is the first long period study concerning the spectral features of HFD variation. The observation and the data, the spectral analysis and the results are reported. The most important factor for dealing with HFD records is the frequency stability of the observation system. The HFD observation detected surely ionospheric variation in the period of 3 - 13 days and 16 - 21 days. (K.I.)

  15. Ionospheric variations in the period range of days to tens of days deduced from HF doppler observation

    Shibata, Takashi; Yoshimura, Yasuo; Okuzawa, Takashi (University of Electro-Communications, Chofu, Tokyo (Japan)); Ogawa, Toshio

    1989-01-01

    The HF Doppler frequency variation of the ionosphere corresponds to ionospheric phase path change, which should be ascribed to traveling ionospheric disturbance, solar flares (UV and X-ray), magnetic pulsation, geomagnetic sudden commencement as well as sudden impulse. Therefore, the HF Doppler variation may possibly be a manifestation of solar-terrestrial activity. In this paper, the results of the spectral analysis of ionospheric variation in the period ranging from a few days to tens of days observed by the HFD method in nearly the whole year of 1986 are reported. For the purpose of comparison, the spectral analysis has been done on the of F2 data and the horizontal component data of the geomagnetic field, which were obtained during the same observation period. The present study is the first long period study concerning the spectral features of HFD variation. The observation and the data, the spectral analysis and the results are reported. The most important factor for dealing with HFD records is the frequency stability of the observation system. The HFD observation detected surely ionospheric variation in the period of 3 - 13 days and 16 - 21 days. (K.I.).

  16. Spectral shearing of quantum light pulses by electro-optic phase modulation

    Wright, Laura J; Soeller, Christoph; Smith, Brian J

    2016-01-01

    Frequency conversion of non-classical light enables robust encoding of quantum information based upon spectral multiplexing that is particularly well-suited to integrated-optics platforms. Here we present an intrinsically deterministic linear-optics approach to spectral shearing of quantum light pulses and show it preserves the wave-packet coherence and quantum nature of light. The technique is based upon an electro-optic Doppler shift to implement frequency shear of heralded single-photon wave packets by +/- 200 GHz, which can be scaled to an arbitrary shift. These results demonstrate a reconfigurable, unitary method to controlling the spectral-temporal mode structure of quantum light.

  17. Doppler term in the galaxy two-point correlation function: wide-angle, velocity, Doppler lensing and cosmic acceleration effects

    Raccanelli, Alvise; Bertacca, Daniele; Jeong, Donghui; Neyrinck, Mark C.; Szalay, Alexander S.

    2016-01-01

    We study the parity-odd part (that we shall call Doppler term) of the linear galaxy two-point correlation function that arises from wide-angle, velocity, Doppler lensing and cosmic acceleration effects. As it is important at low redshift and at large angular separations, the Doppler term is usually neglected in the current generation of galaxy surveys. For future wide-angle galaxy surveys such as Euclid, SPHEREx and SKA, however, we show that the Doppler term must be included. The effect of t...

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

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

    2002-07-01

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

  19. Adaptive Lighting

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... distributed differently into an architectural body. We also examine what might occur when light is dynamic and able to change colour, intensity and direction, and when it is adaptive and can be brought into interaction with its surroundings. In short, what happens to an architectural space when artificial...

  20. Time gap for temporal cloak based on spectral hole burning in atomic medium

    Jabar, M. S. Abdul; Bacha, Bakht Amin; Ahmad, Iftikhar

    2016-08-01

    We demonstrate the possibility of creating a time gap in the slow light based on spectral hole burning in a four-level Doppler broadened sodium atomic system. A time gap is also observed between the slow and the fast light in the hole burning region and near the burnt hole region, respectively. A cloaking time gap is attained in microseconds and no distortion is observed in the transmitted pulse. The width of the time gap is observed to vary with the inverse Doppler effect in this system. Our results may provide a way to create multiple time gaps for a temporal cloak. Project supported by the Higher Education Commission (HEC) of Pakistan.

  1. The other spectral flow

    Gato-Rivera, Beatriz; Gato-Rivera, Beatriz; Rosado, Jose Ignacio

    1995-01-01

    Recently we showed that the spectral flow acting on the N=2 twisted topological theories gives rise to a topological algebra automorphism. Here we point out that the untwisting of that automorphism leads to a spectral flow on the untwisted N=2 superconformal algebra which is different from the usual one. This "other" spectral flow does not interpolate between the chiral ring and the antichiral ring. In particular, it maps the chiral ring into the chiral ring and the antichiral ring into the antichiral ring. We discuss the similarities and differences between both spectral flows. We also analyze their action on null states.

  2. Windowed multipole for cross section Doppler broadening

    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.

  3. Application of HF Doppler measurements for the investigation of internal atmospheric waves in the ionosphere

    Petrova, I. R.; Bochkarev, V. V.; Latipov, R. R.

    2009-09-01

    We present results of the spectral analysis of data series of Doppler frequency shifted signals reflected from the ionosphere, using experimental data received at Kazan University, Russia. Spectra of variations with periods from 1 min to 60 days have been calculated and analyzed for different scales of periods. The power spectral density for spring and winter differs by a factor of 3-4. Local maxima of variation amplitude are detected, which are statistically significant. The periods of these amplitude increases range from 6 to 12 min for winter, and from 24 to 48 min for autumn. Properties of spectra for variations with the periods of 1-72 h have been analyzed. The maximum of variation intensity for all seasons and frequencies corresponds to the period of 24 h. Spectra of variations with periods from 3 to 60 days have been calculated. The maxima periods of power spectral density have been detected by the MUSIC method for the high spectral resolution. The detected periods correspond to planetary wave periods. Analysis of spectra for days with different level of geomagnetic activity shows that the intensity of variations for days with a high level of geomagnetic activity is higher.

  4. Musculoskeletal colour/power Doppler in sports medicine

    Boesen, M I; Boesen, M; Langberg, Henning;

    2010-01-01

    This review article discusses the aspects of sports medicine where musculoskeletal Doppler ultrasound has valuable contribution in diagnosis and/or treatment of some of the typical musculoskeletal sports injuries. Also, conditions where the Doppler ultrasound has no value are discussed. Some...

  5. Monitoring and Analysis of Respiratory Patterns Using Microwave Doppler Radar

    ,

    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 ...

  6. Diagnosis of aortic dissection by color-coded doppler

    Using a new ultrasound technique, the Color-Coded Doppler Echocardiography, the thoracic extension of a previously diagnosed dissecting aneurysm of the abdominal aorta was detected in an asymptomatic patient. The Color-Coded Doppler seems to be a reliable method in diagnosing aortic dissecting aneurysm and the technique of choice for the follow-up of the chronic forms of disease

  7. The Doppler and gravitational components of the cosmological redshift

    We decompose the cosmological redshift in the standard Friedmann cosmologies into two shifts: a Doppler shift attributable to the recession of the galaxies, and a gravitational shift attributable to the curvature of the universe. For galaxies nearby enough for their recessional motion to be non-relativistic, we interpret our results for the Doppler and gravitational shifts with the aid of Birkhoff's theorem. (author)

  8. A study for developing an ultrasonic Doppler flowmeter

    Biermans, M.; Bregman, R.

    1984-06-01

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

  9. Doppler weather radar with predictive wind shear detection capabilities

    Kuntman, Daryal

    1991-01-01

    The status of Bendix research on Doppler weather radar with predictive wind shear detection capability is given in viewgraph form. Information is given on the RDR-4A, a fully coherent, solid state transmitter having Doppler turbulence capability. Frequency generation data, plans, modifications, system characteristics and certification requirements are covered.

  10. Micro-Doppler classification of riders and riderless horses

    Tahmoush, David

    2014-05-01

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

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

    Rothenstein, Bernhard; Nafornita, Corina

    2004-01-01

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

  12. The Sensitivity of Hybrid Differential Stereoscopy for Spectral Imaging

    DeForest, Craig E

    2007-01-01

    Stereoscopic spectral imaging is an observing technique that affords rapid acquisition of limited spectral information over an entire image plane simultaneously. Light from a telescope is dispersed into multiple spectral orders, which are imaged separately, and two or more of the dispersed images are combined using an analogy between the (x,y,\\lambda) spectral data space and conventional (x,y,z) three-space. Because no photons are deliberately destroyed during image acquisition, the technique is much more photon-efficient in some observing regimes than existing techniques such as scanned-filtergraph or scanned-slit spectral imaging. Hybrid differential stereoscopy, which uses a combination of conventional cross-correlation stereoscopy and linear approximation theory to extract the central wavelength of a spectral line, has been used to produce solar Stokes-V (line-of-sight) magnetograms in the 617.34 nm Fe I line, and more sophisticated inversion techniques are currently being used to derive Doppler and line ...

  13. On Longitudinal Spectral Coherence

    Kristensen, Leif

    1979-01-01

    It is demonstrated that the longitudinal spectral coherence differs significantly from the transversal spectral coherence in its dependence on displacement and frequency. An expression for the longitudinal coherence is derived and it is shown how the scale of turbulence, the displacement between ...

  14. Hydrocarbon Spectral Database

    SRD 115 Hydrocarbon Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 91 hydrocarbon molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported.

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

    D. Altadill

    2005-06-01

    Full Text Available Studies of the dynamics of the ionosphere and its related phenomena are mainly based on Doppler Drift measurements. The time variation (ionisation/recombination of plasma density, thermospheric wind and others can be observed by means of HF-radars. The technique of Doppler Drift measurements is a quite complex technique that is now affordable by means of an advanced ionospheric sounder. The combination of vertical sounding and interferometric Doppler detection discloses the Doppler sources. The echo signal contains the Doppler shift in frequency imposed on the wave carrier by each point source where the signal is reflected. Other phenomena like environmental noise and the intrinsic error of the measurements that, together with the change in time of the refractive index, affect the measurements in various ways impeding to better quantify the results.

  16. Limits on Planetary Companions from Doppler Surveys of Nearby Stars

    Howard, Andrew W

    2016-01-01

    Most of our knowledge of planets orbiting nearby stars comes from Doppler surveys. For spaced-based, high-contrast imaging missions, nearby stars with Doppler-discovered planets are attractive targets. The known orbits tell imaging missions where and when to observe, and the dynamically-determined masses provide important constraints for the interpretation of planetary spectra. Quantifying the set of planet masses and orbits that could have been detected will enable more efficient planet discovery and characterization. We analyzed Doppler measurements from Lick and Keck Observatories collected by the California Planet Survey. We focused on stars that are likely targets for three space-based planet imaging mission concepts studied by NASA--WFIRST-AFTA, Exo-C, and Exo-S. The Doppler targets are primarily F8 and later main sequence stars, with observations spanning 1987-2014. We identified 76 stars with Doppler measurements from the prospective mission target lists. We developed an automated planet search and a ...

  17. Use of GPS network data for HF Doppler measurements interpretation

    Petrova, Inna R; Latypov, Ruslan R

    2014-01-01

    The method of measurement of Doppler frequency shift of ionospheric signal - HF Doppler technique - is one of well-known and widely used methods of ionosphere research. It allows to research various disturbances in the ionosphere. There are some sources of disturbances in the ionosphere. These are geomagnetic storms, solar flashes, metrological effects, atmospheric waves. This method allows to find out the influence of earthquakes, explosions and other processes on the ionosphere, which occur near to the Earth. HF Doppler technique has the high sensitivity to small frequency variations and the high time resolution, but interpretation of results is difficult. In this work we make an attempt to use GPS data for Doppler measurements interpretation. Modeling of Doppler frequency shift variations with use of TEC allows to separate ionosphere disturbances of medium scale.

  18. Doplerovi brodski navigacioni brzinomjeri / Maritime navigational Doppler logs

    Milovan Unković

    2006-01-01

    Full Text Available Doplerovi navigacioni brodski brzinomjeri rade na principu Doplerovog efekta. Doplerov predajni projektor emituje snop ultrazvučnih vibracija u vodi, a drugi (ili isti projektor prima odbijeni signal od dna ili od sloja vode. U ovom radu opisana je teorija Doplerovog efekta, primjena te teorije na brodskim brzinomjerima, konstrukcija i karakteristike savremenih Doplerovih brzinomjera. / The Doppler maritime navigational logs are based on measurement of the Doppler effect. A Doppler log transmitting transducer emits beam of sound vibration in the water, and a second (or the same transducer receives the echo from the sea bed or -water layer. In this article describes theory of Doppler effect, using this theory in maritime logs, construction and performance of modern Doppler logs.

  19. Adaptive Lighting

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... the investigations of lighting scenarios carried out in two test installations: White Cube and White Box. The test installations are discussed as large-scale experiential instruments. In these test installations we examine what could potentially occur when light using LED technology is integrated and...

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

    Reiners, A; Ulbrich, R G

    2014-01-01

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

  1. A high-frequency Doppler feature in the power spectra of simulated GRMHD black hole accretion disks

    Black hole binaries exhibit a wide range of variability phenomena, from large-scale state changes to broadband noise and quasi-periodic oscillations, but the physical nature of much of this variability is poorly understood. We examine the variability properties of three GRMHD simulations of thin accretion disks around black holes of varying spin, producing light curves and power spectra as would be seen by observers. We find that the simulated power spectra show a broad feature at high frequency, which increases in amplitude with the inclination of the observer. We show that this high-frequency feature is a product of the Doppler effect and that its location is a function of the mass and spin of the black hole. This Doppler feature demonstrates that power spectral properties of the accretion disk can be tied to, and potentially used to determine, physical properties of the black hole

  2. A High-Frequency Doppler Feature in the Power Spectra of Simulated GRMHD Black Hole Accretion Disks

    Wellons, Sarah; Psaltis, Dimitrios; Narayan, Ramesh; McClintock, Jeffrey E

    2013-01-01

    Black hole binaries exhibit a wide range of variability phenomena, from large-scale state changes to broadband noise and quasi-periodic oscillations, but the physical nature of much of this variability is poorly understood. We examine the variability properties of three GRMHD simulations of thin accretion disks around black holes of varying spin, producing light curves and power spectra as would be seen by observers. We find that the simulated power spectra show a broad feature at high frequency, which increases in amplitude with the inclination of the observer. We show that this high-frequency feature is a product of the Doppler effect and that its location is a function of the mass and spin of the black hole. This Doppler feature demonstrates that power spectral properties of the accretion disk can be tied to, and potentially used to determine, physical properties of the black hole.

  3. The Modulation of Ionospheric Alfvén Resonator on Heating HF Waves and the Doppler Effect

    Ni Bin-bin; Zhao Zheng-yu; Xie Shu-guo

    2003-01-01

    Abstract: The propagation of HF waves in IAR can produce many nonlinear effects, including the modulation effect of IAR on HF waves and the Doppler effect. To start with the dependence of the ionospheric electron temperature variaof the modulation effect and lucubrate possible reasons for the field can have an observable modulation effect on HF waves while its mechanism is quite different from that of Schumann resonant field on HF waves. The depth of modulation of IAR field, which directly inspires the formation of cross-spectrum between ULF waves and HF waves and results in spectral peaks at some gyro-frequencies of IAR. With respect to the Doppler effect during the propagation of HF waves in IAR, it is mainly caused by the motion of the high-speed flyer and the drifting electrons and the frequency shift from the phase variation of the reflected waves can be neglected when the frequency of HF incident wave is high enough.

  4. Adaptive skills

    Staša Stropnik

    2013-02-01

    Full Text Available Adaptive skills are defined as a collection of conceptual, social and practical skills that are learned by people in order to function in their everyday lives. They include an individual's ability to adapt to and manage her or his surroundings to effectively function and meet social or community expectations. Good adaptive skills promote individual's independence in different environments, whereas poorly developed adaptive skills are connected to individual's dependency and with greater need for control and help with everyday tasks. Assessment of adaptive skills is often connected to assessment of intellectual disability, due to the reason that the diagnosis of intellectual disability includes lower levels of achievements on standardized tests of intellectual abilities as well as important deficits in adaptive skills. Assessment of adaptive behavior is a part of standard assessment battery with children and adults with different problems, disorders or disabilities that affect their everyday functioning. This contribution also presents psychometric tools most regularly used for assessment of adaptive skills and characteristics of adaptive skills with individual clinical groups.

  5. ADAPT Dataset

    National Aeronautics and Space Administration — Advanced Diagnostics and Prognostics Testbed (ADAPT) Project Lead: Scott Poll Subject Fault diagnosis in electrical power systems Description The Advanced...

  6. Origin of the SuperDARN broad Doppler spectra:simultaneous observation with Oersted satellite magnetometer

    K. Hosokawa

    2004-01-01

    Full Text Available We perform a case study of a favorable conjunction of an overpass of the Oersted satellite with the field-of-view of the SuperDARN Syowa East radar during an interval of the southward IMF Bz. At the time, the radar observed an L-shell aligned boundary in the spectral width around the dayside ionosphere. Simultaneously, high-frequency (0.2–5Hz magnetic field fluctuations were observed by the Oersted satellite's high-time resolution magnetometer. These magnetic field fluctuations are considered to be Alfvén waves possibly associated with the particle which precipitates into the dayside high-latitude ionosphere when magnetic reconnection occurs. It has been theoretically predicted that the time-varying electric field is the dominant physical process to expand the broad HF radar Doppler spectra. Our observation clearly demonstrates that the boundary between narrow and broad spectral widths is corresponding well to the boundary in the level of the fluctuations, which supports the previous theoretical prediction. A close relationship between electric and magnetic field fluctuations and particle precipitations during southward IMF conditions has been confirmed by many authors. The present observation allows us to suggest that the boundary between narrow and broad Doppler spectral widths observed in the dayside ionosphere is connected with the signature of the open/closed field line boundary, such as the cusp particle precipitations via electric and magnetic field fluctuations for the case of the negative IMF Bz conditions.

    Key words. Ionosphere (ionosphere-magnetosphere interactions; plasma convection. Magnetospheric physics (magnetopause, cusp, and boundary layers

  7. A spectral sequence for parallelized persistence

    Lipsky, David; Vejdemo-Johansson, Mikael

    2011-01-01

    We approach the problem of the computation of persistent homology for large datasets by a divide-and-conquer strategy. Dividing the total space into separate but overlapping components, we are able to limit the total memory residency for any part of the computation, while not degrading the overall complexity much. Locally computed persistence information is then merged from the components and their intersections using a spectral sequence generalizing the Mayer-Vietoris long exact sequence. We describe the Mayer-Vietoris spectral sequence and give details on how to compute with it. This allows us to merge local homological data into the global persistent homology. Furthermore, we detail how the classical topology constructions inherent in the spectral sequence adapt to a persistence perspective, as well as describe the techniques from computational commutative algebra necessary for this extension. The resulting computational scheme suggests a parallelization scheme, and we discuss the communication steps invol...

  8. Temporal shape analysis via the spectral signature.

    Bernardis, Elena; Konukoglu, Ender; Ou, Yangming; Metaxas, Dimitris N; Desjardins, Benoit; Pohl, Kilian M

    2012-01-01

    In this paper, we adapt spectral signatures for capturing morphological changes over time. Advanced techniques for capturing temporal shape changes frequently rely on first registering the sequence of shapes and then analyzing the corresponding set of high dimensional deformation maps. Instead, we propose a simple encoding motivated by the observation that small shape deformations lead to minor refinements in the spectral signature composed of the eigenvalues of the Laplace operator. The proposed encoding does not require registration, since spectral signatures are invariant to pose changes. We apply our representation to the shapes of the ventricles extracted from 22 cine MR scans of healthy controls and Tetralogy of Fallot patients. We then measure the accuracy score of our encoding by training a linear classifier, which outperforms the same classifier based on volumetric measurements. PMID:23286031

  9. Hole-burning in an Autler-Townes doublet and in superluminal (subluminal) Electromagnetically induced transparency of a light pulse via a joint nonlinear coherent Kerr effect and Doppler broadening

    Bacha, Bakhtt A; Ahmad, Iftikhar

    2013-01-01

    We investigate the behavior of light pulse propagation in a 4-level double Lambda atomic system under condition of electromagnetically induced transparency. The Fano type interference effect and spectral hole burning appears in the the dynamics of the absorption-dispersion spectra caused by the joint nonlinear coherence Kerr effect and Doppler broadening. The coherent Kerr effect exhibits an enhancement (reduction) in superluminal (subluminal) in negative (in positive) group index while the Doppler broadening generates multiple hole burning in the Autler-Townes like spectra of this system. The hole burning in addition with coherent Kerr effect on the spectral profile influences the dynamics of subluminal and superluminal of the probe pulse through the medium. The characteristics of superluminality and subluminality modified by considering cold-Kerr-free medium and hot-Kerr-dependent mediums. The light pulse delays and advances in different regions of dispersion medium with the Doppler broadening and coherent ...

  10. Spectral analysis and filter theory in applied geophysics

    Buttkus, Burkhard

    2000-01-01

    This book is intended to be an introduction to the fundamentals and methods of spectral analysis and filter theory and their appli­ cations in geophysics. The principles and theoretical basis of the various methods are described, their efficiency and effectiveness eval­ uated, and instructions provided for their practical application. Be­ sides the conventional methods, newer methods arediscussed, such as the spectral analysis ofrandom processes by fitting models to the ob­ served data, maximum-entropy spectral analysis and maximum-like­ lihood spectral analysis, the Wiener and Kalman filtering methods, homomorphic deconvolution, and adaptive methods for nonstation­ ary processes. Multidimensional spectral analysis and filtering, as well as multichannel filters, are given extensive treatment. The book provides a survey of the state-of-the-art of spectral analysis and fil­ ter theory. The importance and possibilities ofspectral analysis and filter theory in geophysics for data acquisition, processing an...

  11. The Doppler peaks from a generic defect

    Magueijo, J

    1996-01-01

    We investigate which of the exotic Doppler peak features found for textures and cosmic strings are generic novelties pertaining to defects. We find that the ``out of phase'' texture signature is an accident. Generic defects, when they generate a secondary peak structure similar to inflation, apply to it an additive shift. It is not necessary for this shift to be ``out of phase''. We also show which factors are responsible for the absence of secondary oscillations found for cosmic strings. Within this general analysis we finally consider the conditions under which topological defects and inflation can be confused. It is argued that only \\Omega=1 inflation and a defect with a horizon size coherence length have a chance to be confused. Any other inflationary or defect model always differ distinctly. (To appear in the proceedings of the XXXIth Moriond meeting, ``Microwave Background Anisotropies'')

  12. Spacecraft Doppler tracking with a VLBI antenna

    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.

  13. Microscale Heat Conduction Models and Doppler Feedback

    The objective of this project is to establish an approach for providing the fundamental input that is needed to estimate the magnitude and time-dependence of the Doppler feedback mechanism in Very High Temperature reactors. This mechanism is the foremost contributor to the passive safety of gas-cooled, graphite-moderated high temperature reactors that use fuel based on Tristructural-Isotropic (TRISO) coated particles. Therefore, its correct prediction is essential to the conduct of safety analyses for these reactors. Since the effect is directly dependent on the actual temperature reached by the fuel during transients, the underlying phenomena of heat deposition, heat transfer and temperature rise must be correctly predicted. To achieve the above objective, this project will explore an approach that accounts for lattice effects as well as local temperature variations and the correct definition of temperature and related local effects.

  14. Correlation and Sequential Filtering with Doppler Measurements

    WANGJianguo; HEPeikun; HANYueqiu; WUSiliang

    2004-01-01

    Two sequential filters are developed for Doppler radar measurements in the presence of correlation between range and range rate measurement errors. Two ideal linear measurement equations with the pseudo measurements are constructed via block-partitioned Cholesky factorization and the practical measurement equationswith the pseudo measurements are obtained through the direction cosine estimation and error compensation. The resulting sequential filters make the position measurement be possibly processed before the pseudo measurement and hence the more accurate direction cosine estimate can be obtained from the filtered position estimate rather than the predicted state estimate. The numerical simulations with different rangerange rate correlation coefficients show thatthe proposed two sequential filters are almost equivalent in performance but both superior to the conventional extended Kalman filter for different correlation coefficients.

  15. Position finding using simple Doppler sensors

    S. Schelkshorn

    2007-06-01

    Full Text Available An increasing number of modern applications and services is based on the knowledge of the users actual position. Depending on the application a rough position estimate is sufficient, e. g. services in cellular networks that use the information about the users actual cell. Other applications, e. g. navigation systems use the GPS-System for accurate position finding. Beyond these outdoor applications a growing number of indoor applications requires position information. The previously mentioned methods for position finding (mobile cell, GPS are not usable for these indoor applications.

    Within this paper we will present a system that relies on the simultaneous measurement of doppler signals at four different positions to obtain position and velocity of an unknown object. It is therefore suiteable for indoor usage, extendig already existing wireless infrastructure.

  16. Implementation of Doppler backscattering for MAST

    Hillesheim, J C; Peebles, W A; Meyer, H; Meakins, A; Field, A R; Dunai, D; Carr, M; Hawkes, N

    2014-01-01

    A sixteen channel millimeter-wave diagnostic system, covering the frequency range 30-75 GHz, has been installed on MAST [B. Lloyd et al., Nucl. Fusion 43, 1665 (2003)] and has been successfully used for both Doppler backscattering (DBS) and conventional (normal-incidence) fluctuation reflectometry. DBS has become a well-established and versatile diagnostic technique for the measurement of intermediate- k ($k_{\\bot} \\rho_i \\sim 1$, and higher) density fluctuations and flows in magnetically confined fusion experiments. The $180^{\\circ}$ backscattering for DBS requires three dimensional wave-vector matching between the launched beam and the plasma fluctuations inducing the scattering, which are expected to be highly elongated along the magnetic field. The large pitch angle in MAST means that DBS implementation depends strongly on the capability to accurately launch the probing beam at a toroidal and poloidal angle that is matched to the magnetic field at the scattering location. We report on the scattering consi...

  17. DC coupled Doppler radar physiological monitor.

    Zhao, Xi; Song, Chenyan; Lubecke, Victor; Boric-Lubecke, Olga

    2011-01-01

    One of the challenges in Doppler radar systems for physiological monitoring is a large DC offset in baseband outputs. Typically, AC coupling is used to eliminate this DC offset. Since the physiological signals of interest include frequency content near DC, it is not desirable to simply use AC coupling on the radar outputs. While AC coupling effectively removes DC offset, it also introduces a large time delay and distortion. This paper presents the first DC coupled IQ demodulator printed circuit board (PCB) design and measurements. The DC coupling is achieved by using a mixer with high LO to RF port isolation, resulting in a very low radar DC offset on the order of mV. The DC coupled signals from the PCB radar system were successfully detected with significant LNA gain without saturation. Compared to the AC coupled results, the DC coupled results show great advantages of less signal distortion and more accurate rate estimation. PMID:22254704

  18. The recondite intricacies of Zeeman Doppler mapping

    Stift, M J; Cowley, C R

    2011-01-01

    We present a detailed analysis of the reliability of abundance and magnetic maps of Ap stars obtained by Zeeman Doppler mapping (ZDM). It is shown how they can be adversely affected by the assumption of a mean stellar atmosphere instead of appropriate "local" atmospheres corresponding to the actual abundances in a given region. The essenceof the difficulties was already shown by Chandrasekhar's picket-fence model. The results obtained with a suite of Stokes codes written in the Ada programming language and based on modern line-blanketed atmospheres are described in detail. We demonstrate that the high metallicity values claimed to have been found in chemically inhomogeneous Ap star atmospheres would lead to local temperature structures, continuum and line intensities, and line shapes that differ significantly from those predicted by a mean stellar atmosphere. Unfortunately, past applications of ZDM have consistently overlooked the intricate aspects of metallicity with their all-pervading effects. The erroneou...

  19. Microscale Heat Conduction Models and Doppler Feedback

    Hawari, Ayman I. [North Carolina State Univ., Raleigh, NC (United States); Ougouag, Abderrafi [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-01-22

    The objective of this project is to establish an approach for providing the fundamental input that is needed to estimate the magnitude and time-dependence of the Doppler feedback mechanism in Very High Temperature reactors. This mechanism is the foremost contributor to the passive safety of gas-cooled, graphite-moderated high temperature reactors that use fuel based on Tristructural-Isotropic (TRISO) coated particles. Therefore, its correct prediction is essential to the conduct of safety analyses for these reactors. Since the effect is directly dependent on the actual temperature reached by the fuel during transients, the underlying phenomena of heat deposition, heat transfer and temperature rise must be correctly predicted. To achieve the above objective, this project will explore an approach that accounts for lattice effects as well as local temperature variations and the correct definition of temperature and related local effects.

  20. Widefield laser doppler velocimeter: development and theory.

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

    2007-03-01

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

  1. Doppler cooling and trapping on forbidden transitions

    Binnewies, T; Sterr, U; Riehle, F; Helmcke, J; Mehlstäubler, T E; Rasel, E M; Ertmer, W

    2001-01-01

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of ^40Ca atoms has been cooled and trapped to a temperature as low as 6 \\mu K by operating a magneto-optical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method more than 10% of pre-cooled atoms from a standard magneto-optical trap have been transferred to the ultracold trap. Monte-Carlo simulations of the cooling process are in good agreement with the experiments.

  2. Doppler cooling and trapping on forbidden transitions.

    Binnewies, T; Wilpers, G; Sterr, U; Riehle, F; Helmcke, J; Mehlstäubler, T E; Rasel, E M; Ertmer, W

    2001-09-17

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of (40)Ca atoms has been cooled and trapped to a temperature as low as 6 microK by operating a magnetooptical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method, more than 10% of precooled atoms from a standard magnetooptical trap have been transferred to the ultracold trap. Monte Carlo simulations of the cooling process are in good agreement with the experiments. PMID:11580503

  3. Ultrasonic intrusion sensor using the Doppler effect; Choonpa Doppler hoshiki shinnyu sensor

    Kani, H.; Iwasaki, N.; Goto, M. [Nippon Soken, Inc., Tokyo (Japan); Tsuzuki, T.; Nakamura, T. [Denso Corp., Aichi (Japan)

    1997-10-01

    For vehicle anti-theft alarm systems which cope with vehicle and car component theft, EU initiated vehicle security regulations from Jan 1997. Also, the insurance industry has instituted the insurance certification of vehicle anti-theft alarm systems. We have developed an ultrasonic intrusion sensor using the doppler effect for vehicle anti-theft alarm systems specifically for these EU regulations and insurance certification. 2 refs., 7 figs., 1 tab.

  4. Electrophysiological measurements of spectral sensitivities: a review

    R.D. DeVoe

    1997-02-01

    Full Text Available Spectral sensitivities of visual systems are specified as the reciprocals of the intensities of light (quantum fluxes needed at each wavelength to elicit the same criterion amplitude of responses. This review primarily considers the methods that have been developed for electrophysiological determinations of criterion amplitudes of slow-wave responses from single retinal cells. Traditional flash methods can require tedious dark adaptations and may yield erroneous spectral sensitivity curves which are not seen in such modifications as ramp methods. Linear response methods involve interferometry, while constant response methods involve manual or automatic adjustments of continuous illumination to keep response amplitudes constant during spectral scans. In DC or AC computerized constant response methods, feedback to determine intensities at each wavelength is derived from the response amplitudes themselves. Although all but traditional flash methods have greater or lesser abilities to provide on-line determinations of spectral sensitivities, computerized constant response methods are the most satisfactory due to flexibility, speed and maintenance of a constant adaptation level

  5. Wind Field Measurements With Airborne Doppler Lidar

    Menzies, Robert T.

    1999-01-01

    In collaboration with lidar atmospheric remote sensing groups at NASA Marshall Space Flight Center and National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory, we have developed and flown the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) lidar on the NASA DC-8 research aircraft. The scientific motivations for this effort are: to obtain measurements of subgrid scale (i.e. 2-200 km) processes and features which may be used to improve parameterizations in global/regional-scale models; to improve understanding and predictive capabilities on the mesoscale; and to assess the performance of Earth-orbiting Doppler lidar for global tropospheric wind measurements. MACAWS is a scanning Doppler lidar using a pulsed transmitter and coherent detection; the use of the scanner allows 3-D wind fields to be produced from the data. The instrument can also be radiometrically calibrated and used to study aerosol, cloud, and surface scattering characteristics at the lidar wavelength in the thermal infrared. MACAWS was used to study surface winds off the California coast near Point Arena, with an example depicted in the figure below. The northerly flow here is due to the Pacific subtropical high. The coastal topography interacts with the northerly flow in the marine inversion layer, and when the flow passes a cape or point that juts into the winds, structures called "hydraulic expansion fans" are observed. These are marked by strong variation along the vertical and cross-shore directions. The plots below show three horizontal slices at different heights above sea level (ASL). Bottom plots are enlargements of the area marked by dotted boxes above. The terrain contours are in 200-m increments, with the white spots being above 600-m elevation. Additional information is contained in the original.

  6. Optical coherence techniques for plasma doppler spectroscopy

    A new electro-optically Modulated Optical Solid-State (MOSS) interferometer has been constructed for measurement of the low order spectral moments of line emission from optically thin radiant media. The instrument, which is based on the principle of the Fourier transform spectrometer, has high etendue and is rugged, compact and inexpensive. By employing electro-optical path-length modulation techniques, the spectral information is transferred to the temporal frequency domain and can be obtained using a single photodetector. Specifically, the zeroth moment (brightness) is given by the average signal level, the first moment (shift) by the modulation phase and the second moment (line width) by the modulation amplitude. (author)

  7. Adaptive spectral clustering algorithm based on Nystr(o)m method with multi-level structure in LUV color space%LUV色彩空间中多层次化结构Nystr(o)m方法的自适应谱聚类算法

    刘雅蓉; 汪西莉

    2012-01-01

    In this paper, we propose an adaptive spectral clustering algorithm based on the Nystrom method with multilevel structures in LUV color space. First, we introduce the LUV color space, which can effectively avoid the influence of barely noticeable differences on the segmentation results, achieving better result in texture and edge regions. Second, we combine the spectral clustering algorithm based on multi-level structure and the Nystrom method. Our approach can reduce the operation time and solve the problem of memory overflow. Finally, in X-means, through the analysis of the eigengap to adaptive select the value of K, this approach can automatically determine the number of clusters. The proposed method is applied to image segmentation, respectively, in LUV color space and RGB color space. The experimental results show that in LUV color space we can obtain even better results. The data computation and operation time as well as the segmentation result of the proposed algorithm are superior, compared to the spectral clustering algorithm based on the Nystrom method (SC-N).%提出一种在LUV空间中基于多层次化结构Nystr(o)m方法的自适应谱聚类算法.首先引入LUV色彩空间,避免了RGB色彩空间中色彩辨别阈对分割的影响,在纹理、边缘区域取得了更好的分割效果;其次将谱聚类算法中基于多层次化结构的方法和基于Nystr(o)m采样的方法结合起来,有效减少了运算时间、解决了数据量较大时计算过程中内存溢出的问题;最后在K均值聚类中通过对特征间隙( eigengap)的分析,自适应地选择K值的大小,解决了自动确定聚类数目的问题.将提出的方法在LUV色彩空间中和RGB色彩空间中分别进行图像分割实验,结果表明在LUV色彩空间中取得效果更加理想.同时也将提出的算法与基于Nystr(o)m方法的谱聚类算法(spectral clustering-Nystr(o)m,SC-N)进行比较.实验结果表明,该算法在数据运算量、运行时

  8. Spectral radius of graphs

    Stevanovic, Dragan

    2014-01-01

    Spectral Radius of Graphs provides a thorough overview of important results on the spectral radius of adjacency matrix of graphs that have appeared in the literature in the preceding ten years, most of them with proofs, and including some previously unpublished results of the author. The primer begins with a brief classical review, in order to provide the reader with a foundation for the subsequent chapters. Topics covered include spectral decomposition, the Perron-Frobenius theorem, the Rayleigh quotient, the Weyl inequalities, and the Interlacing theorem. From this introduction, the

  9. Spectral width of SuperDARN echoes: measurement, use and physical interpretation

    P. V. Ponomarenko

    2006-03-01

    Full Text Available The Doppler velocity and spectral width are two important parameters derived from coherent scatter radar systems. The Super Dual Auroral Radar Network (SuperDARN is capable of monitoring most of the high latitude region where different boundaries of the magnetosphere map to the ionosphere. In the past, the spectral width, calculated from SuperDARN data, has been used to identify the ionosphere footprints of various magnetosphere boundaries. In this paper we examine the way the spectral width is presently estimated from the radar data and describe several recommendations for improving the algorithm. Using the improved algorithm, we show that typical spectral width values reported in the literature are most probably overestimated. The physical interpretation of the cause of various magnitudes of the spectral width is explored in terms of the diffusion and dynamics of ionospheric plasma irregularities.

  10. Color Doppler ultrasonography in oral squamous cell carcinoma: Making ultrasonography more meaningful

    Rahul Gandhi

    2015-01-01

    Full Text Available Background: Although color Doppler ultrasonography (CD-USG is useful in the diagnosis of various diseases of the head and neck, flow signals in the malignant oral tumors are less studied; hence, the present study was designed to study the usefulness of CD-USG in quantifying oral squamous cell carcinoma (OSCC vascularization and in determining the hemodynamic parameters by spectral analysis obtained during CD-USG procedure. Aims: To study the usefulness of CD-USG in mapping OSCC of buccal mucosa, tongue, and lip. Materials and Methods: This was a case-control study, conducted among 60 subjects aged 20–70 years. Group A consisted of 30 cases of OSCC of buccal mucosa, tongue, and lip while Group B consisted of 30 controls. CD-USG investigation of each mass was carried out. The spectral waveform (time-velocity Doppler spectrum of flow signal was analyzed for the pulsatility index, resistivity index (RI, peak systolic velocity (PSV (m/s, and end diastolic velocity (EDV (m/s. All patients had real-time, gray-scale sonography and CD-USG with spectral wave analysis. Results: In this study, the mean value for RI in patients with malignancy was 0.40 ± 0.14 whereas for healthy subjects, it was 0.83 ± 0.07. Mean value for PI in patients with malignancy was 0.86 ± 0.20 whereas for healthy subjects, it was 2.61 ± 0.77. In the present study, the mean PSV in malignant masses was 31.72 ± 13.48 whereas for healthy subjects, it was 43.87 ± 20.95, and the EDV in malignant masses was 10.33 ± 5.21 whereas for healthy subjects, it was 7.07 ± 3.44. Conclusion: The said Doppler indices were shown to be sensitive as well as specific for the diagnosis of malignant oral tumors. Although CD-USG cannot replace histopathological procedures, it plays a definite role as an adjunct to the clinical evaluation of OSCC cases.

  11. Pulsed Doppler echocardiographic analysis of mitral regurgitation after myocardial infarction.

    Loperfido, F; Biasucci, L M; Pennestri, F; Laurenzi, F; Gimigliano, F; Vigna, C; Rossi, E; Favuzzi, A; Santarelli, P; Manzoli, U

    1986-10-01

    In 72 patients with previous myocardial infarction (MI), mitral regurgitation (MR) was assessed by pulsed-wave Doppler echocardiography and compared with physical and 2-dimensional echocardiographic findings. MR was found by Doppler in 29 of 42 patients (62%) with anterior MI, 11 of 30 (37%) with inferior MI (p less than 0.01) and in none of 20 normal control subjects. MR was more frequent in patients who underwent Doppler study 3 months after MI than in those who underwent Doppler at discharge (anterior MI = 83% vs 50%, p less than 0.01; inferior MI = 47% vs 27%, p = not significant). Of 15 patients who underwent Doppler studies both times, 3 (all with anterior MI) had MR only on the second study. Of the patients with Doppler MR, 12 of 27 (44%) with a left ventricular (LV) ejection fraction (EF) greater than 30% and 1 of 13 (8%) with an EF of 30% or less (p less than 0.01) had an MR systolic murmur. Mitral prolapse or eversion and papillary muscle fibrosis were infrequent in MI patients, whether or not Doppler MR was present. The degree of Doppler MR correlated with EF (r = -0.61), LV systolic volume (r = 0.47), and systolic and diastolic mitral anulus circumference (r = 0.52 and 0.51, respectively). Doppler MR was present in 24 of 28 patients (86%) with an EF of 40% or less and in 16 of 44 (36%) with EF more than 40% (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3766410

  12. Vowel Inherent Spectral Change

    Assmann, Peter

    2013-01-01

    It has been traditional in phonetic research to characterize monophthongs using a set of static formant frequencies, i.e., formant frequencies taken from a single time-point in the vowel or averaged over the time-course of the vowel. However, over the last twenty years a growing body of research has demonstrated that, at least for a number of dialects of North American English, vowels which are traditionally described as monophthongs often have substantial spectral change. Vowel Inherent Spectral Change has been observed in speakers’ productions, and has also been found to have a substantial effect on listeners’ perception. In terms of acoustics, the traditional categorical distinction between monophthongs and diphthongs can be replaced by a gradient description of dynamic spectral patterns. This book includes chapters addressing various aspects of vowel inherent spectral change (VISC), including theoretical and experimental studies of the perceptually relevant aspects of VISC, the relationship between ar...

  13. Mitigating Doppler shift effect in HF multitone data modem

    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.

  14. [Feasibility study of the Doppler exploration of the renal artery].

    Milon, P; Clavier, E; Genevois, A; Benozio, M

    1990-03-01

    Using arteriography as a reference, the authors investigate the feasibility of pulsed doppler exploration of the normal or pathological renal arteries in 46 successive patients. The poor sensitivity of pulsed doppler, mainly due to the considerable anatomical variations of the renal pedicle, does not currently allow using this technique for the detection of renal arterial stenosis. When combined with angiography, pulsed doppler becomes a definite asset in therapeutic radiology to help in the choice of a treatment and in follow-up. PMID:2191123

  15. Sub-Doppler laser cooling of potassium atoms

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

    2011-01-01

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

  16. Sub-Doppler laser cooling of potassium atoms

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

    2011-10-15

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

  17. Procedures for quality control in Doppler ultrasound equipment

    Different international recommendations suggest an application of quality control programs in ultrasound equipment. However, procedures and reference values for Doppler test are not yet well defined. This work aims to present quantitative and qualitative tests for evaluation of quality control at Doppler ultrasound equipment. The following tests were performed: Doppler Signal Sensitivity; Color Flow Sensitivity; Flow Sensitivity at Depth; Color Flow B-Mode Image Congruency; Directional Discrimination; Accuracy of Flow Velocity Readout and Accuracy of Sample Gate Positioning. The values found will be used as baseline for comparisons over time. (author)

  18. Rotational Doppler Effect and Barnett Field in Spinning NMR

    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.

  19. Coherent Doppler wind lidars in a turbulent atmosphere

    Banakh, Viktor

    2013-01-01

    Radiophysical tools for measuring atmospheric dynamics include sodars, Doppler radars, and Doppler lidars. Among these, coherent Doppler lidars (CDLs) have been considered the best for remote measurement of wind turbulence. This is important not only for understanding the exchange processes in the boundary layer, but also in the applied aspect, such as aviation safety. CDLs significantly extend possibilities of experimental investigation of not only wind turbulence, but also coherent structures such as aircraft wake vortices. The authors of this book conducted field tests of the developed meth

  20. Considerations pertinent to the Doppler effect for space reactors

    This paper describes various theoretical aspects pertinent to the estimation of the Doppler effect for space reactors. The distinct characteristics of space reactors give rise to various issues that are not present in the more thoroughly studied Doppler effect of fast breeder reactors. Key issues concerning the existing resonance data and computational models are extensively discussed. Calculations of the Doppler coefficient for a generic space reactor design having features of current designs have also been carried out to illustrate various aspects of practical importance

  1. Interferometric millimeter wave and THz wave doppler radar

    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.

  2. LCTF Spectral Parameters Stability

    Pons, Alicia; Peralta, Celia; Campos, Joaquín; Negueruela, Angel I.; Rabal, A.; Martínez, T.

    2009-01-01

    Liquid crystal tunable filters (LCTF) are being widely used as spectral analysis system in different applications, particularly in color imaging and multispectral imaging. This work presents a study on the stability, at short and long terms, of the parameters defining the bandpass function: spectral distribution of transmittance maximum, bandwidth and mean or effective wavelength, λm, calculated according to the Full Wide Half Maximum (FWHM) criterion. Measurements have been made by a direct ...

  3. Spectrally selective glazings

    NONE

    1998-08-01

    Spectrally selective glazing is window glass that permits some portions of the solar spectrum to enter a building while blocking others. This high-performance glazing admits as much daylight as possible while preventing transmission of as much solar heat as possible. By controlling solar heat gains in summer, preventing loss of interior heat in winter, and allowing occupants to reduce electric lighting use by making maximum use of daylight, spectrally selective glazing significantly reduces building energy consumption and peak demand. Because new spectrally selective glazings can have a virtually clear appearance, they admit more daylight and permit much brighter, more open views to the outside while still providing the solar control of the dark, reflective energy-efficient glass of the past. This Federal Technology Alert provides detailed information and procedures for Federal energy managers to consider spectrally selective glazings. The principle of spectrally selective glazings is explained. Benefits related to energy efficiency and other architectural criteria are delineated. Guidelines are provided for appropriate application of spectrally selective glazing, and step-by-step instructions are given for estimating energy savings. Case studies are also presented to illustrate actual costs and energy savings. Current manufacturers, technology users, and references for further reading are included for users who have questions not fully addressed here.

  4. Thermophotovoltaic Spectral Control

    DM DePoy; PM Fourspring; PF Baldasaro; JF Beausang; EJ Brown; MW Dashiel; KD Rahner; TD Rahmlow; JE Lazo-Wasem; EJ Gratrix; B Wemsman

    2004-06-09

    Spectral control is a key technology for thermophotovoltaic (TPV) direct energy conversion systems because only a fraction (typically less than 25%) of the incident thermal radiation has energy exceeding the diode bandgap energy, E{sub g}, and can thus be converted to electricity. The goal for TPV spectral control in most applications is twofold: (1) Maximize TPV efficiency by minimizing transfer of low energy, below bandgap photons from the radiator to the TPV diode. (2) Maximize TPV surface power density by maximizing transfer of high energy, above bandgap photons from the radiator to the TPV diode. TPV spectral control options include: front surface filters (e.g. interference filters, plasma filters, interference/plasma tandem filters, and frequency selective surfaces), back surface reflectors, and wavelength selective radiators. System analysis shows that spectral performance dominates diode performance in any practical TPV system, and that low bandgap diodes enable both higher efficiency and power density when spectral control limitations are considered. Lockheed Martin has focused its efforts on front surface tandem filters which have achieved spectral efficiencies of {approx}83% for E{sub g} = 0.52 eV and {approx}76% for E{sub g} = 0.60 eV for a 950 C radiator temperature.

  5. Spectral flow inside essential spectrum

    Azamov, Nurulla

    2014-01-01

    The spectral flow is a classical notion of functional analysis and differential geometry which was given different interpretations as Fredholm index, Witten index, and Maslov index. The classical theory treats spectral flow outside the essential spectrum. Inside essential spectrum, the spectral shift function could be considered as a proper analogue of spectral flow, but unlike the spectral flow, the spectral shift function is not an integer-valued function. In this paper it is shown that the...

  6. Fingerprints of a riming event on cloud radar Doppler spectra: observations and modeling

    Kalesse, Heike; Szyrmer, Wanda; Kneifel, Stefan; Kollias, Pavlos; Luke, Edward

    2016-03-01

    Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediment through a supercooled liquid water (SLW) layer. The focus is on the "golden sample" case study for this type of analysis based on observations collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland, during the Biogenic Aerosols - Effects on Clouds and Climate (BAECC) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are considered by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. This suggests that in situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations.

  7. Differentiation between Malignant and Benign Masses of Thyroid Gland Using Color Doppler Ultrasonogram

    Son, Chang Woo; Kim, Chang Woo; Sin, Se Kwon; Jang, Kyeung Jae [Dae Dong Hospital, Busan (Korea, Republic of); Kim, Yi Tae [Dong A Hospital, Busan (Korea, Republic of)

    1996-12-15

    To determine color Doppler ultrasound findings of malignant and benign thyroid nodules, and to identify differential points among them. 35 patients with palpable enlarged thyroid nodules were imaged by using with 7 MHz linear-array transducer. Color Doppler images were obtained in the transverse and longitudinal planes on the color setting for the thyroid gland. After setting receiver gain, velocity scale and filter were set to 6 cm / sec and 1, respectively. And we measured resistive index, pulsatility index, peak systolic velocity and end diastolic velocity from the fastest or next fast arterial signals in the thyroid nodules or in the margins of the thyroid nodules. Final diagnosis was confirmed by ultrasonography-guided or surgical biopsy. 25 cases of malignant nodule and 10 cases of benign nodule were confirmed histopathologically.On the color mapping, malignant nodules showed various internal flow signals from avascular to hyper vascular and no marginal flow signals in all cases, and benign nodules revealed 9 (36%) hypo vascular cases and 16 (64%)hyper vascular cases in the internal flow signals and increased marginal flow signals in all cases. On the spectral analysis, malignant nodules showed RI 0.7 (0.63{approx}0.83) in hyper vascular internal flow signals and RI 0.93(0.67{approx}1.00) in hypo vascular internal flow signals, and measured PI was 1.39 (1.03{approx}2.11), 2.71 (0.97{approx}4.81),respectively. and in benign nodules, measured RI was 0.65 (0.5{approx}0.88) and PI was 0.92 (0.59{approx}1.90). Color Doppler imaging can be helpful to differentiate benign and malignant thyroid masses by means of measuring marginal and internal flow signals of thyroid nodules

  8. Differentiation between Malignant and Benign Masses of Thyroid Gland Using Color Doppler Ultrasonogram

    To determine color Doppler ultrasound findings of malignant and benign thyroid nodules, and to identify differential points among them. 35 patients with palpable enlarged thyroid nodules were imaged by using with 7 MHz linear-array transducer. Color Doppler images were obtained in the transverse and longitudinal planes on the color setting for the thyroid gland. After setting receiver gain, velocity scale and filter were set to 6 cm / sec and 1, respectively. And we measured resistive index, pulsatility index, peak systolic velocity and end diastolic velocity from the fastest or next fast arterial signals in the thyroid nodules or in the margins of the thyroid nodules. Final diagnosis was confirmed by ultrasonography-guided or surgical biopsy. 25 cases of malignant nodule and 10 cases of benign nodule were confirmed histopathologically.On the color mapping, malignant nodules showed various internal flow signals from avascular to hyper vascular and no marginal flow signals in all cases, and benign nodules revealed 9 (36%) hypo vascular cases and 16 (64%)hyper vascular cases in the internal flow signals and increased marginal flow signals in all cases. On the spectral analysis, malignant nodules showed RI 0.7 (0.63∼0.83) in hyper vascular internal flow signals and RI 0.93(0.67∼1.00) in hypo vascular internal flow signals, and measured PI was 1.39 (1.03∼2.11), 2.71 (0.97∼4.81),respectively. and in benign nodules, measured RI was 0.65 (0.5∼0.88) and PI was 0.92 (0.59∼1.90). Color Doppler imaging can be helpful to differentiate benign and malignant thyroid masses by means of measuring marginal and internal flow signals of thyroid nodules

  9. A doppler-based evaluation of peripheral lower limb arterial insufficiency in diabetes mellitus

    To determine the frequency, level and flow patterns of lower limb arterial insufficiency in diabetic patients on Doppler ultrasound study. Study Design: Cross-sectional study. Place and Duration of Study: Radiology Department, Civil Hospital, Karachi, from February 2007 to September 2008. Methodology: One hundred adult diabetic patients with suspected peripheral vascular insufficiency irrespective of gender were included. Demographic data, presenting complaints, treatment history, and level of HbA1c were recorded. Doppler evaluated arterial status and ankle brachial index (ABI) were recorded on proforma. Statistical analysis were done on SPSS version 12. Results: The mean HbA1c was 8.4 +- 1.4 gm/dl, a majority of 77% having a controlled level of < 10 mg/dl. Arterial insufficiency on Doppler ultrasound was documented in 62% (p=0.016) and the dorsalis paedis artery was the predominant site of stenosis (24%). Spectral broadening and biphasic flow were salient features. The mean value of resistive index in stenotic cases was 0.563 +- 0.16 with a mean velocity difference of 0.37 +- 0.29 m/s (p < 0.001) at the site of stenosis. Conclusion: Peripheral vascular insufficiency was a significant finding in patients having diabetes for an average of 9.8 years, even in the presence of controlled HbA1c. The dorsalis paedis was the commonest site of involvement. The insufficiency was moderate with a biphasic flow pattern in a majority of cases. Difference in resistive index and flow velocities at and above the site of stenosis provided an important clue to the diagnosis of level of stenosis that helps in planning limb salvage management. (author)

  10. The Next Generation Airborne Polarimetric Doppler Radar

    Vivekanandan, J.; Lee, Wen-Chau; Loew, Eric; Salazar, Jorge; Chandrasekar, V.

    2013-04-01

    NCAR's Electra Doppler radar (ELDORA) with a dual-beam slotted waveguide array using dual-transmitter, dual-beam, rapid scan and step-chirped waveform significantly improved the spatial scale to 300m (Hildebrand et al. 1996). However, ELDORA X-band radar's penetration into precipitation is limited by attenuation and is not designed to collect polarimetric measurements to remotely estimate microphysics. ELDORA has been placed on dormancy because its airborne platform (P3 587) was retired in January 2013. The US research community has strongly voiced the need to continue measurement capability similar to the ELDORA. A critical weather research area is quantitative precipitation estimation/forecasting (QPE/QPF). In recent years, hurricane intensity change involving eye-eyewall interactions has drawn research attention (Montgomery et al., 2006; Bell and Montgomery, 2006). In the case of convective precipitation, two issues, namely, (1) when and where convection will be initiated, and (2) determining the organization and structure of ensuing convection, are key for QPF. Therefore collocated measurements of 3-D winds and precipitation microphysics are required for achieving significant skills in QPF and QPE. Multiple radars in dual-Doppler configuration with polarization capability estimate dynamical and microphysical characteristics of clouds and precipitation are mostly available over land. However, storms over complex terrain, the ocean and in forest regions are not observable by ground-based radars (Bluestein and Wakimoto, 2003). NCAR/EOL is investigating potential configurations for the next generation airborne radar that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. ELDORA's slotted waveguide array radar is not compatible for dual-polarization measurements. Therefore, the new design has to address both dual-polarization capability and platform requirements to replace the ELDORA system. NCAR maintains a C-130

  11. Turbulent energy dissipation rates observed by Doppler MST Radar and by rocket-borne instruments during the MIDAS/MaCWAVE campaign 2002

    N. Engler

    2005-06-01

    Full Text Available During the MIDAS/MaCWAVE campaign in summer 2002 we have observed turbulence using Doppler beam steering measurements obtained from the ALWIN VHF radar at Andøya/Northern Norway. This radar was operated in the Doppler beam steering mode for turbulence investigations during the campaign, as well as in spaced antenna mode, for continuously measuring the background wind field. The real-time data analysis of the Doppler radar backscattering provided the launch conditions for the sounding rockets. The spectral width data observed during the occurrence of PMSE were corrected for beam and shear broadening caused by the background wind field to obtain the turbulent part of the spectral width. The turbulent energy dissipation rates determined from the turbulent spectral width vary between 5 and 100mW kg-1 in the altitude range of 80-92km and increase with altitude. These estimations agree well with the in-situ measurements using the CONE sensor which was launched on 3 sounding rockets during the campaign.

  12. Using FLCT to Obtain Spectral Information From MOSES Data

    Courrier, Hans; Kankelborg, Charles

    2014-06-01

    The Multi-Order Solar EUV Spectrograph (MOSES) is a high cadence slitless spectrograph that images in He II 304Å. The large field of view (20’x10’) combined with the ability to quickly obtain images containing both spectral and spatial information makes MOSES an ideal platform for probing small scale, short duration flows resulting from magnetic reconnection in the solar transition region. The ease of obtaining co-temporal spectral and spatial data with a slitless spectrograph is counterbalanced by increased difficulty required to disentangling the information captured in the images. The Fourier Local Correlation Tracking (FLCT) routine developed by Fischer and Welch (2007) is developed as a technique for obtaining Doppler shifts and line widths from small scale flows imaged by MOSES. Results are reported utilizing this technique on simulated images and MOSES data.

  13. Improved Micro Rain Radar snow measurements using Doppler spectra post-processing

    M. Maahn

    2012-11-01

    Full Text Available The Micro Rain Radar 2 (MRR is a compact Frequency Modulated Continuous Wave (FMCW system that operates at 24 GHz. The MRR is a low-cost, portable radar system that requires minimum supervision in the field. As such, the MRR is a frequently used radar system for conducting precipitation research. Current MRR drawbacks are the lack of a sophisticated post-processing algorithm to improve its sensitivity (currently at +3 dBz, spurious artefacts concerning radar receiver noise and the lack of high quality Doppler radar moments. Here we propose an improved processing method which is especially suited for snow observations and provides reliable values of effective reflectivity, Doppler velocity and spectral width. The proposed method is freely available on the web and features a noise removal based on recognition of the most significant peak. A dynamic dealiasing routine allows observations even if the Nyquist velocity range is exceeded. Collocated observations over 115 days of a MRR and a pulsed 35.2 GHz MIRA35 cloud radar show a very high agreement for the proposed method for snow, if reflectivities are larger than −5 dBz. The overall sensitivity is increased to −14 and −8 dBz, depending on range. The proposed method exploits the full potential of MRR's hardware and substantially enhances the use of Micro Rain Radar for studies of solid precipitation.

  14. An ion Doppler spectrometer instrument for ion temperature and flow measurements on SSPX

    A high-resolution ion Doppler spectrometer (IDS) has been installed on the sustained spheromak plasma experiment to measure ion temperatures and plasma flow. The system is composed of a 1 m focal length Czerny-Turner spectrometer with a diffraction grating line density of 2400 lines/mm, which allows for first order spectra between 300 and 600 nm. A 16-channel photomultiplier tube detection assembly combined with output coupling optics provides a spectral resolution of 0.0126 nm/channel. We calculate in some detail the mapping of curved slit images onto the linear detector array elements. This is important in determining the wavelength resolution and setting the optimum vertical extent of the slit. Also, because of the small wavelength window of the IDS, a miniature fiber-optic survey spectrometer sensitive to a wavelength range 200-1100 nm and having a resolution of 0.2 nm is used to obtain a time-integrated spectrum for each shot to verify specific impurity line radiation. Several measurements validate the systems operation. Doppler broadening of C III 464.72 nm line in the plasma shows time-resolved ion temperatures up to 250 eV for hydrogen discharges, which is consistent with neutral particle energy analyzer measurements. Flow measurements show a sub-Alfvenic plasma flow ranging from 5 to 45 km/s for helium discharges.

  15. An all-fiber image-reject homodyne coherent Doppler wind lidar

    Foroughi Abari, Farzad; Pedersen, Anders Tegtmeier; Mann, Jakob

    2014-01-01

    In this paper, we present an alternative approach to the down-conversion (translation) of the received optical signals collected by the antenna of an all-fiber coherent Doppler lidar (CDL). The proposed method, widely known as image-reject, quadrature detection, or in-phase/quadrature-phase detec......In this paper, we present an alternative approach to the down-conversion (translation) of the received optical signals collected by the antenna of an all-fiber coherent Doppler lidar (CDL). The proposed method, widely known as image-reject, quadrature detection, or in......-phase/quadrature-phase detection, utilizes the advances in fiber optic communications such that the received signal can be optically down-converted into baseband where not only the radial velocity but also the direction of the movement can be inferred. In addition, we show that by performing a cross-spectral analysis, enabled by...... measurement of radial velocities close to zero and an improved bandwidth. The claims are verified through laboratory implementation of a continuous wave CDL, where measurements both on a hard and diffuse target have been performed and analyzed. © 2014 Optical Society of America...

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

    2016-01-01

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

  17. Sub-Doppler infrared spectroscopy of propargyl radical (H2CCCH) in a slit supersonic expansion

    The acetylenic CH stretch mode (ν1) of propargyl (H2CCCH) radical has been studied at sub-Doppler resolution (∼60 MHz) via infrared laser absorption spectroscopy in a supersonic slit-jet discharge expansion, where low rotational temperatures (Trot = 13.5(4) K) and lack of spectral congestion permit improved determination of band origin and rotational constants for the excited state. For the lowest J states primarily populated in the slit jet cooled expansion, fine structure due to the unpaired electron spin is resolved completely, which permits accurate analysis of electron spin-rotation interactions in the vibrationally excited states (εaa = − 518.1(1.8), εbb = − 13.0(3), εcc = − 1.8(3) MHz). In addition, hyperfine broadening in substantial excess of the sub-Doppler experimental linewidths is observed due to nuclear spin–electron spin contributions at the methylenic (—CH2) and acetylenic (—CH) positions, which permits detailed modeling of the fine/hyperfine structure line contours. The results are consistent with a delocalized radical spin density extending over both methylenic and acetylenic C atoms, in excellent agreement with simple resonance structures as well as ab initio theoretical calculations

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

    Gianfrani, Livio

    2016-03-28

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

  19. Color Doppler Imaging of Ophthalmic Arteries : Age Related Changes in the Normal Subjects

    Color Doppler imaging (CDI) with Doppler spectral analysis was done to evaluate the age related changes of the ophthalmic arteries in 60 normotensive subjects (Age : 19∼64y, mean =38.3y, M : F = 1 : 1). A 7 MHz linear transducer for small parts (Acuson L7384) was used. The ophthalmic artery about 1∼1.5 cm behind the optic nerve head was depicted by the CDI. The maximum peak velocity (S1), the second peak velocity (S2), the maximum peak diastolic velocity (D1) and the end diastolic velocity (D*2) were recorded. Additionally, the piteously index(PI), the resistive index (RI), the ratio of S1 to S2 (S1 / S2) and the ratio of S1 to D1 (S1 / D1) were calculated. Correlation between the age and the above indices (ratio) was estimated. PI, RI, S1 / S2 and S1 / D1 declined progressively as a function of advancing age. The S1 / S2 showed the strongest inverse correlation with age (r = -0.667). The meaning of the S2's in old age is not clear. It could be related to the decreased compliance of the aged ophthalmic arteries

  20. Ambiguous Adaptation

    Møller Larsen, Marcus; Lyngsie, Jacob

    We investigate why some exchange relationships terminate prematurely. We argue that investments in informal governance structures induce premature termination in relationships already governed by formal contracts. The formalized adaptive behavior of formal governance structures and the flexible and...... reciprocal adaptation of informal governance structure create ambiguity in situations of contingencies, which, subsequently, increases the likelihood of premature relationship termination. Using a large sample of exchange relationships in the global service provider industry, we find support for a hypothesis...

  1. Strategic Adaptation

    Andersen, Torben Juul

    2015-01-01

    This article provides an overview of theoretical contributions that have influenced the discourse around strategic adaptation including contingency perspectives, strategic fit reasoning, decision structure, information processing, corporate entrepreneurship, and strategy process. The related...... concepts of strategic renewal, dynamic managerial capabilities, dynamic capabilities, and strategic response capabilities are discussed and contextualized against strategic responsiveness. The insights derived from this article are used to outline the contours of a dynamic process of strategic adaptation...

  2. Analysis of multiple scattering effects in optical Doppler tomography

    Yura, H.T.; Thrane, L.; Andersen, Peter E.

    2005-01-01

    Doppler frequency spectrum. Thus, in the present analysis, the dependence of the mean and standard deviation of the Doppler shift on the scattering properties of the flowing medium are obtained. Taking the multiple scattering effects into account, we are able to explain previous measurements of depth......Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where...... multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed...

  3. Laser Doppler instrument measures fluid velocity without reference beam

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

    1971-01-01

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

  4. Numerical studies of HF Doppler variations caused by ionospheric disturbances

    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.

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

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

    2008-11-01

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

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

    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.

  7. Estimation of amputation level with a laser Doppler flowmeter

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

    1989-01-01

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

  8. Modifications and Moving Measurements of Mobile Doppler LIDAR

    Liu, Bing-Yi; Liu, Zhi-Shen; Song, Xiao-Quan; Wu, Song-Hua; Bi, De-Cang; Wang, Xi-Tao; Yin, Qi-Wei; Reitebuch, Oliver

    2010-10-01

    In the last annual report of ID. 5291 LIDAR Cal/Val, a mobile Doppler lidar had been developed for 3D wind measurements by the Chinese partners from Ocean Remote Sensing Institute, Ocean University of China. In this year, in order to further improve the mobility of the mobile Doppler lidar for lidar calibration and validation, both GPS and inertial navigation system are integrated on the vehicle for performing measurements during movement. The modifications of the system and the results of the moving measurements are presented. This work simplifies the construction of the mobile Doppler system and makes the lidar more flexible for ground-based wind measurements and validation with the ADM-Aeolus spaceborne Doppler lidar.

  9. Calculation of doppler coefficient of reactivity by WIMS code

    The Doppler coefficient of reactivity is an important factor in prediction of several transients in light water reactors. Some of the past studies raised the question about the 10% uncertainty that traditionally was taken in calculations of Doppler coefficient by LWR lattice code. In order to bridge the gap of lack of accurate benchmark problem to evaluate the accuracy of Doppler effect, Mosteller et al. proposed a computational benchmark problem of Doppler coefficient to evaluate the accuracy and consistency of LWR lattice physics code. In this paper we present the results obtained from WIMS-D4 lattice code and compare it with those obtained by CELL-2 lattice code part of the EPRI-PRESS reactor physics package. The results obtained from the Monte Carlo code MCNP-3A served as reference for both cases, and was taken from ref 1. (authors). 4 refs., 2 figs., 1 tab

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

    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)

  11. Doppler Compensation by using of Segmented Match Filter

    Nader Ghadimi

    2008-09-01

    Full Text Available Match filter is one of the important parts of radar receiver. By using of Match Filter, the signal to noise ratio can be maximized so that the probability of detection is increased. Match Filter can be used as a pulse compression filter in radar receiver. Binary phase code is one of the pulse compression methods that, the compression can be down with a Match Filter in the receiver. Doppler effect is one of the problems that degrade the performance of Match Filter. In this paper, two methods “Mixer Array” and “Segmented Match Filter” are proposed for Doppler compensation. The operation of these two methods as Doppler compensation techniques are considered theoretically. The simulation is used to demonstrate the Doppler compensation performance of new techniques compared to conventional methods.

  12. Design of new seismometer based on laser Doppler effect

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

    2004-01-01

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

  13. Calculation of the Doppler broadening function using Fourier analysis

    An efficient and precise method for calculation of Doppler broadening function is very important to obtain average group microscopic cross sections, self shielding factors, resonance integrals and others reactor physics parameter. In this thesis two different methods for calculation of Doppler broadening function and interference term will be presented. The main method is based on a new integral form for Doppler broadening function ψ(x,ζ) which gives a mathematical interpretation of the approximation proposed by Bethe and Placzek, as the convolution of the Lorentzian function with a Gaussian function. This interpretation besides leading to a new integral form for ψ(x,ζ), enables to obtain a simple analytic solution for the Doppler broadening function. (author)

  14. Laser Doppler technology applied to atmospheric environmental operating problems

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

    1976-01-01

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

  15. Ultrasonic Doppler methods to extract signatures of a walking human.

    Mehmood, Asif; Sabatier, James M; Damarla, Thyagaraju

    2012-09-01

    Extraction of Doppler signatures that characterize human motion has attracted a growing interest in recent years. These Doppler signatures are generated by various components of the human body while walking, and contain unique features that can be used for human detection and recognition. Although, a significant amount of research has been done in radio frequency regime for human Doppler signature extraction, considerably less has been done in acoustics. In this work, 40 kHz ultrasonic sonar is employed to measure the Doppler signature generated by the motion of body segments using different electronic and signal processing schemes. These schemes are based on both analog and digital demodulation with homodyne and heterodyne receiver circuitry. The results and analyses from these different schemes are presented. PMID:22979839

  16. Doppler ultrasound in obstetrics and gynecology. 2. rev. and enl. ed.

    Maulik, D. [Winthrop Univ. Hospital, Mineola, NY (United States). Dept. of Obstetrics and Gynecology; Zalud, I. (eds.) [Kapiolani Medical Center for Women and Children, Honolulu, HI (United States)

    2005-07-01

    The second edition of Doppler Ultrasound in Obstetrics and Gynecology has been expanded and comprehensively updated to present the current standards of practice in Doppler ultrasound and the most recent developments in the technology. Doppler Ultrasound in Obstetrics and Gynecology encompasses the full spectrum of clinical applications of Doppler ultrasound for the practicing obstetrician-gynecologist, including the latest advances in 3D and color Doppler and the newest techniques in 4D fetal echocardiography. Written by preeminent experts in the field, the book covers the basic and physical principles of Doppler ultrasound; the use of Doppler for fetal examination, including fetal cerebral circulation; Doppler echocardiography of the fetal heart; and the use of Doppler for postdated pregnancy and in cases of multiple gestation. Chapters on the use of Doppler for gynecologic investigation include ultrasound in ectopic pregnancy, for infertility, for benign disorders and for gynecologic malignancies. (orig.)

  17. Doppler ultrasound in obstetrics and gynecology. 2. rev. and enl. ed.

    The second edition of Doppler Ultrasound in Obstetrics and Gynecology has been expanded and comprehensively updated to present the current standards of practice in Doppler ultrasound and the most recent developments in the technology. Doppler Ultrasound in Obstetrics and Gynecology encompasses the full spectrum of clinical applications of Doppler ultrasound for the practicing obstetrician-gynecologist, including the latest advances in 3D and color Doppler and the newest techniques in 4D fetal echocardiography. Written by preeminent experts in the field, the book covers the basic and physical principles of Doppler ultrasound; the use of Doppler for fetal examination, including fetal cerebral circulation; Doppler echocardiography of the fetal heart; and the use of Doppler for postdated pregnancy and in cases of multiple gestation. Chapters on the use of Doppler for gynecologic investigation include ultrasound in ectopic pregnancy, for infertility, for benign disorders and for gynecologic malignancies. (orig.)

  18. High Spectral Resolution Lidar: System Calibration

    Vivek Vivekanandan, J.; Morley, Bruce; Spuler, Scott; Eloranta, Edwin

    2015-04-01

    One of the unique features of the high spectral resolution lidar (HSRL) is simultaneous measurements of backscatter and extinction of atmosphere. It separates molecular scattering from aerosol and cloud particle backscatter based on their Doppler spectrum width. Scattering from aerosol and cloud particle are referred as Mie scattering. Molecular or Rayleigh scattering is used as a reference for estimating aerosol extinction and backscatter cross-section. Absolute accuracy of the backscattered signals and their separation into Rayleigh and Mie scattering depends on spectral purity of the transmitted signals, accurate measurement of transmit power, and precise performance of filters. Internal calibration is used to characterize optical subsystems Descriptions of high spectral resolution lidar system and its measurement technique can be found in Eloronta (2005) and Hair et al.(2001). Four photon counting detectors are used to measure the backscatter from the combined Rayleigh and molecular scattering (high and low gain), molecular scattering and cross-polarized signal. All of the detectors are sensitive to crosstalk or leakage through the optical filters used to separate the received signals and special data files are used to remove these effects as much as possible. Received signals are normalized with respect to the combined channel response to Mie and Rayleigh scattering. The laser transmit frequency is continually monitored and tuned to the 1109 Iodine absorption line. Aerosol backscatter cross-section is measured by referencing the aerosol return signal to the molecular return signal. Extinction measurements are calculated based on the differences between the expected (theoretical) and actual change in the molecular return. In this paper an overview of calibration of the HSRL is presented. References: Eloranta, E. W., High Spectral Resolution Lidar in Lidar: Range-Resolved Optical Remote Sensing of the Atmosphere, Klaus Weitkamp editor, Springer Series in Optical

  19. Localizing Plages on BO Mic, First steps towards chromospheric Doppler imaging

    Wolter, U

    2005-01-01

    We have obtained a densely sampled time series of CaII H&K line profiles of the ultrafast rotating K-dwarf star BO Mic. Taken at high resolution, the spectra reveal pronounced variations of the emission core profiles. We interpret these variations as signs of concentrated chromospherically active regions, in analogy to solar plages. We further interpret the variations as partly due to the rapid growth and decay of plages, while other variations appear to be caused by plages moved over the visible stellar disk by rotation. The equivalent width of the Ca K core emission changes approximately in anti-phase to the photospheric brightness, suggesting an association of the chromospheric plage regions with pronounced dark photospheric spots. We believe that further analysis of the presented spectral time series will lead to a chromospheric Doppler image of BO mic.

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

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

    2016-01-01

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

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

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

    2016-08-01

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

  2. Limits on the Doppler factor in relativistic jets by means of gamma-ray observations

    Dean, A. J.; Bassani, L.

    1985-01-01

    A new, simple and potentially useful method for constraining the kinematical parameters of relativistic jets based on gamma ray spectral measurements of Active Galaxies is presented. The application of this method to the Quasar 3C273 leads to a value of the Doppler factor of 3 to 4. This corresponds to jet parameters of mu 2 and theta 15 deg in good agreement with the values estimated independently from radio observations of superluminal motion. For the particular case of 3C273, the results are also compared to those given by a similar technique based on the comparison of the X-ray observational data with the synchrotron self Compton prediction from radio measurements. The application of the proposed technique to a significant sample of active galaxies as a result of future gamma ray surveys of the sky is briefly discussed, particularly with respect to possible ways to constrain the cosmological constants H sub o and q sub o.

  3. Limits on the Doppler factor in relativistic jets by means of gamma-ray observations

    A new, simple and potentially useful method for constraining the kinematical parameters of relativistic jets based on gamma ray spectral measurements of Active Galaxies is presented. The application of this method to the Quasar 3C273 leads to a value of the Doppler factor of 3 to 4. This corresponds to jet parameters of mu 2 and theta 15 deg in good agreement with the values estimated independently from radio observations of superluminal motion. For the particular case of 3C273, the results are also compared to those given by a similar technique based on the comparison of the X-ray observational data with the synchrotron self Compton prediction from radio measurements. The application of the proposed technique to a significant sample of active galaxies as a result of future gamma ray surveys of the sky is briefly discussed, particularly with respect to possible ways to constrain the cosmological constants H sub o and q sub o

  4. Intrauterine growth retardation : prediction of perinatal distress by doppler ultrasound

    Reuwer, P.J.H.M.; Rietman, G.W.; Sijmens, E.A.; Tiel, M.W.M. van; Bruinse, H.W.

    1987-01-01

    To investigate the ability of umbilical artery Doppler findings to identify true cases at risk of fetal distress among 51 pregnancies clinically judged to be compromised by intrauterine growth retardation (IUGR) Doppler data were related to pregnancy outcome, which was classified into three groups—group 1, healthy babies with normal placental function (16 fetuses), group 2, fetuses with definite signs of placental failure (30), and group 3, non-classifiable pregnancies (5). Group 2 was subdiv...

  5. Use of GPS network data for HF Doppler measurements interpretation

    Petrova, Inna R.; Bochkarev, Vladimir V.; Latypov, Ruslan R.

    2014-01-01

    The method of measurement of Doppler frequency shift of ionospheric signal - HF Doppler technique - is one of well-known and widely used methods of ionosphere research. It allows to research various disturbances in the ionosphere. There are some sources of disturbances in the ionosphere. These are geomagnetic storms, solar flashes, metrological effects, atmospheric waves. This method allows to find out the influence of earthquakes, explosions and other processes on the ionosphere, which occur...

  6. Fetal echo doppler for early detection of congenital heart block

    Bergman, Gunnar

    2010-01-01

    Background: Fetal echo Doppler methods detecting prolonged atrioventricular (AV) time intervals, a mechanical PR interval corresponding to the electrical PR interval in ECG, have been proposed for surveillance of pregnancies at risk of complete congenital heart block (CCHB). The aim of this thesis was; to validate these Doppler methods by comparing AV time intervals from left ventricular inflow (MV), inflow and aortic outflow (MV-Ao) and superior vena cava and aortic flow ...

  7. Using doppler radar images to estimate aircraft navigational heading error

    Doerry, Armin W.; Jordan, Jay D.; Kim, Theodore J.

    2012-07-03

    A yaw angle error of a motion measurement system carried on an aircraft for navigation is estimated from Doppler radar images captured using the aircraft. At least two radar pulses aimed at respectively different physical locations in a targeted area are transmitted from a radar antenna carried on the aircraft. At least two Doppler radar images that respectively correspond to the at least two transmitted radar pulses are produced. These images are used to produce an estimate of the yaw angle error.

  8. Diagnosis of cervical cancer with transvaginal color Doppler sonography

    Li-bo DENG; Wei ZHOU; Chang, Shu-Fang; Ming-jie LIN

    2011-01-01

    Objective To investigate the imaging features of cervical cancer by transvaginal color Doppler sonography(TVCS),and evaluate the diagnostic value of TVCS.Methods A hundred and thirty cases of cervical intraepithelial neoplasia(CIN) grade Ⅰ-Ⅱ and cervical cancer,diagnosed by Thinprep cytologic test(TCT),cervical biopsy and pathological examination,received TVCS examination.The image characters and color Doppler flow imaging(CDFI) were collected and analyzed.Another 41 cases with normal cervice...

  9. Color doppler ultrasound diagonosis in cesarean scar pregnancy

    Objective: To study the sonographic characteristics of cesarean scar pregnancy(CSP), and the value of color Doppler in the diagnosis of CSP. Methods: Twelve cases of CSP were all confirmed by transabdominal and transvaginal ultrasound. Results: The ultrasonogram of CSP could be divided into gestational sac type and mixed mass type. Conclusion: Color Doppler can give guidance to the early diagnosis, treatment and following-up of CSP because of the sonographic specifity of CSP. (authors)

  10. Doppler Tomography in Cataclysmic Variables: an historical perspective

    Echevarria, J.

    2012-01-01

    To mark the half-century anniversary of this newly-born field of Cataclysmic Variables, a special emphasis is made in this review, on the Doppler Effect as a tool in astrophysics. The Doppler Effect was in fact, discovered almost 170 years ago, and has been since, one of the most important tools which helped to develop modern astrophysics. We describe and discuss here, its use in Cataclysmic Variables which, combined with another important tool, the tomography, first devised for medical purpo...

  11. Physiological and pathophysiological cerebrovascular regulation monitored by transcranial doppler

    Hellström, Gunnar

    1997-01-01

    PHYSIOLOGICAL AND PATHOPHYSIOLOGICAL CEREBROVASCULAR REGULATION MONITORED BY TRANSCRANIAL DOPPLER Thesis by Gunnar Hellström, M D., Department of Clinical Neuroscience, Division of Neurology, Karolinska Hospital and Insbtute, Stocknolm, Sweden Transcranial Doppler ultrasonography (TCD) became available in the middle of the 1980s as a new technique for examinmg cerebral circulation. With this technique it is possible to measure the velocity of blood flow in major ...

  12. Experimental Observation of Reversed Doppler Effects in Acoustic Metamaterials

    Zhai, Shilong; Zhao, Xiaopeng; Liu, Song; Luo, Chunrong

    2015-01-01

    This paper reports an experimental observation of broadband reversed Doppler effects using an acoustic metamaterial with seven flute-like double-meta-molecule clusters. Simulations and experiments verify that this locally resonant acoustic metamaterial with simultaneous negative elastic modulus and mass density can realize negative refraction in a broad frequency range. The constructed metamaterial exhibits broadband reversed Doppler effects. The frequency shift increases continuously as the ...

  13. Doppler velocimetry for predicting fetal death in a twin pregnancy.

    Soikkeli, Pia; Dubiel, Mariusz; Gudmundsson, Saemundur

    2002-01-01

    Diagnosis of discordant twins is easily accomplished with modern ultrasound equipment, though diagnosing twin-to-twin transfusion syndrome (TTS) at an early stage might be a problem. The possibility of excluding TTS by Doppler ultrasound is demonstrated in a case with early severe growth restriction of one fetus. Characteristic blood velocity changes in a dying fetus are also illustrated. The Doppler technique has become an accepted method in obstetrics for antenatal surveillance, perm...

  14. Radar target recognition based on micro-Doppler effect

    DONG Wei-guang; LI Yan-jun

    2008-01-01

    Mechanical vibration of target structures will modulate the phase function of radar backscattering, and will induce thefrequency modulation of returned signals from the target. It generates a side bands of the target body Doppler frequencyshift, which is helpful for target recognition. Based on this.a micro-Doppler atomic storehouse is built for the targetrecognition, and four kinds of common classifiers are used separately to perform the classified recognition. The simulationexperimental results show that this method has high recognition rate above 90%.

  15. Multiple and dependent scattering effects in Doppler optical coherence tomography

    Kalkman, J; Bykov, A. V.; Faber, D.J.; Leeuwen, van

    2010-01-01

    Doppler optical coherence tomography (OCT) is a technique to image tissue morphology and to measure flow in turbid media. In its most basic form, it is based on single (Mie) scattering. However, for highly scattering and dense media multiple and concentration dependent scattering can occur. For Intralipid solutions with varying scattering strength, the effect of multiple and dependent scattering on the OCT signal attenuation and Doppler flow is investigated. We observe a non-linear increase i...

  16. Narrowing of EIT resonance in a Doppler Broadened Medium

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

    2001-01-01

    We derive an analytic expression for the linewidth of EIT resonance in a Doppler broadened system. It is shown here that for relatively low intensity of the driving field the EIT linewidth is proportional to the square root of intensity and is independent of the Doppler width, similar to the laser induced line narrowing effect by Feld and Javan. In the limit of high intensity we recover the usual power broadening case where EIT linewidth is proportional to the intensity and inversely proporti...

  17. Precision Measuring of Velocities via the Relativistic Doppler Effect

    Ozernoy, Leonid M.

    1997-01-01

    Just as the ordinary Doppler effect serves as a tool to measure radial velocities of celestial objects, so can the relativistic Doppler effect be implemented to measure a combination of radial and transverse velocities by using recent improvements in observing techniques. A key element that makes a further use of this combination feasible is the periodicity in changes of the orbital velocity direction for the source. Two cases are considered: (i) a binary star; and (ii) a solitary star with t...

  18. An Overview of the Adaptive Robust DFT

    Djurović Igor

    2010-01-01

    Full Text Available Abstract This paper overviews basic principles and applications of the robust DFT (RDFT approach, which is used for robust processing of frequency-modulated (FM signals embedded in non-Gaussian heavy-tailed noise. In particular, we concentrate on the spectral analysis and filtering of signals corrupted by impulsive distortions using adaptive and nonadaptive robust estimators. Several adaptive estimators of location parameter are considered, and it is shown that their application is preferable with respect to non-adaptive counterparts. This fact is demonstrated by efficiency comparison of adaptive and nonadaptive RDFT methods for different noise environments.

  19. Is adaptation. Truly an adaptation? Is adaptation. Truly an adaptation?

    Thais Flores Nogueira Diniz

    2008-04-01

    Full Text Available The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition, joined with the study of recycling, remaking, and every form of retelling. The film deals with the attempt by the scriptwriter Charles Kaufman, cast by Nicholas Cage, to adapt/translate a non-fictional book to the cinema, but ends up with a kind of film which is by no means what it intended to be: a film of action in the model of Hollywood productions. During the process of creation, Charles and his twin brother, Donald, undergo a series of adventures involving some real persons from the world of film, the author and the protagonist of the book, all of them turning into fictional characters in the film. In the film, adaptation then signifies something different from itstraditional meaning. The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition

  20. Muscle activity characterization by laser Doppler Myography

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

    2013-09-01

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

  1. Doppler findings in intrapartum fetal distress.

    Eslamian, Laleh; Tooba, Khatereh

    2011-01-01

    The umbilical vein (UV) has a non pulsating and even pattern in normal fetuses. Pulsation of UV has been described in severely growth restricted fetuses with chronic hypoxia. We wanted to see whether UV pulsations could also be seen in fetuses with heart deceleration during labor, as an adjunctive measure to assess the intra partum hypoxia. In a prospective study Doppler examination was performed on 34 fetuses with normal cardiotocography (CGT) and 26 fetuses with abnormal CTGs (GA>37w and cervical dilatation>3cm). Perinatal outcome was assessed according to presence or absence of UV pulsations. The 2 groups were similar regarding gestational age, cervical dilatation, Umbilical artery blood pH, S/D ratio,Pulsatility Index( PI) and Resistance Index (RI). Intraabdominal UV pulsation were present in 6 (23.1%) of abnormal CTG group but no case were seen in normal CTG group (P= 0.005). Five of 6 (83.3%) fetuses with UV pulsation underwent cesarean delivery. The rate of cesarean delivery was 90% in abnormal CTG group without pulsation and 14.7% in normal CTG group. The frequency of Apgar score Apgar sore <7or NICU admission were seen. PMID:22009812

  2. Muscle activity characterization by laser Doppler Myography

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

  3. New developments in photon Doppler velocimetry

    Photon Doppler velocimetry (PDV) has made the transition among many experimental groups from being a new diagnostic to being routinely fielded as a means of obtaining velocity data in high-speed test applications. Indeed, research groups both within and outside of the shock physics community have taken note of PDV's robust, high-performance measurement capabilities. As PDV serves as the primary diagnostic in an increasing number of experiments, it will continue to find new applications and enable the measurement of previously un-measurable phenomena. This paper provides a survey of recent developments in PDV system design and feature extraction as well as a discussion of new applications for PDV. More specifically, changes at the system level have enabled the collection of data sets that are far richer than those previously attainable in terms of spatial and temporal coverage as well as improvements over PDV's previously measurable velocity ranges. And until recently, PDV data have been analyzed almost exclusively in the frequency-domain; although the use of additional data analysis techniques is beginning to show promise, particularly as it pertains to extracting information from a PDV signal about surface motion that is not along the beam's axis.

  4. Hydronephrosis and pregnancy: study with Doppler echography

    An 18-month study was performed to establish the normal intrarenal resistance index during pregnancy, in order to determine whether it differed significantly depending on the week of gestation or the degree of hydronephrosis. For this purpose , the flow velocity waves obtained in right kidney were analyzed in a group of 112 patients on the basis of 209 explorations. The kidneys were classified as grade 0,I,II, or III according to the degree of hydronephrosis. Doppler signal sampling was carried out at the level of the corticomedullary junction. From the results of the study it can be deduced that the index of intrarenal resistance during pregnancy is similar to that of the general population, that there are no significant differences among the groups with different degree of hydronephrosis and that the index does not vary according to the different weeks of gestation. These findings suggest that, during pregnancy, a pathological resistance index in a kidney should not be attributed to the physiological changes associated with normal gestation. (Author) 21 refs

  5. Doppler effect induced spin relaxation boom

    Zhao, Xinyu; Huang, Peihao; Hu, Xuedong

    2016-03-01

    We study an electron spin qubit confined in a moving quantum dot (QD), with our attention on both spin relaxation, and the product of spin relaxation, the emitted phonons. We find that Doppler effect leads to several interesting phenomena. In particular, spin relaxation rate peaks when the QD motion is in the transonic regime, which we term a spin relaxation boom in analogy to the classical sonic boom. This peak indicates that a moving spin qubit may have even lower relaxation rate than a static qubit, pointing at the possibility of coherence-preserving transport for a spin qubit. We also find that the emitted phonons become strongly directional and narrow in their frequency range as the qubit reaches the supersonic regime, similar to Cherenkov radiation. In other words, fast moving excited spin qubits can act as a source of non-classical phonons. Compared to classical Cherenkov radiation, we show that quantum dot confinement produces a small but important correction on the Cherenkov angle. Taking together, these results have important implications to both spin-based quantum information processing and coherent phonon dynamics in semiconductor nanostructures.

  6. Evaluating microcirculation by pulsatile laser Doppler signal

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

    2006-02-01

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

  7. A test and simulation device for Doppler-based fetal heart rate monitoring

    Mert, Ahmet; Mana SEZDİ; Akan, Aydin

    2015-01-01

    The Doppler effect is the preferred technique in fetal heart rate (FHR) monitoring devices. The main objective of the recent studies on the Doppler FHR has been to improve the accuracy. On the other hand, a reliable fetal heart simulator becomes essential for testing Doppler FHR monitoring devices. The motivation of this study is to design a reliable system that will be used to test Doppler FHR monitors. This device generates a similar Doppler frequency shift of fetal cardiac activity includi...

  8. High spectral resolution lidar to measure optical scattering properties of atmospheric aerosols. I - Theory and instrumentation

    Shipley, S. T.; Tracy, D. H.; Eloranta, E. W.; Roesler, F. L.; Weinman, J. A.; Trauger, J. T.; Sroga, J. T.

    1983-01-01

    A high spectral resolution lidar technique to measure optical scattering properties of atmospheric aerosols is described. Light backscattered by the atmosphere from a narrowband optically pumped oscillator-amplifier dye laser is separated into its Doppler broadened molecular and elastically scattered aerosol components by a two-channel Fabry-Perot polyetalon interferometer. Aerosol optical properties, such as the backscatter ratio, optical depth, extinction cross section, scattering cross section, and the backscatter phase function, are derived from the two-channel measurements.

  9. High Spectral Resolution Lidar Measurements of Extinction and Particle Size in Clouds

    Eloranta, E. W.; Piirronen, P.

    1996-01-01

    The University of Wisconsin High Spectral Resolution Lidar (HSRL) measures optical properties of the atmosphere by separating the Doppler broadened molecular backscatter return from the unbroadened aerosol return. In the past, the HSRL employed a 150 mm diameter Fabry-Perot etalon to separate the aerosol and molecular signals. The replacement of the etalon with an I2 absorption filter significantly improved the ability of the HSRL to separate weak molecular signals inside dense clouds.

  10. Analysis of Radar Doppler Signature from Human Data

    M. ANDRIĆ

    2014-04-01

    Full Text Available This paper presents the results of time (autocorrelation and time-frequency (spectrogram analyses of radar signals returned from the moving human targets. When a radar signal falls on the human target which is moving toward or away from the radar, the signals reflected from different parts of his body produce a Doppler shift that is proportional to the velocity of those parts. Moving parts of the body causes the characteristic Doppler signature. The main contribution comes from the torso which causes the central Doppler frequency of target. The motion of arms and legs induces modulation on the returned radar signal and generates sidebands around the central Doppler frequency, referred to as micro-Doppler signatures. Through analyses on experimental data it was demonstrated that the human motion signature extraction is better using spectrogram. While the central Doppler frequency can be determined using the autocorrelation and the spectrogram, the extraction of the fundamental cadence frequency using the autocorrelation is unreliable when the target is in the clutter presence. It was shown that the fundamental cadence frequency increases with increasing dynamic movement of people and simultaneously the possibility of its extraction is proportional to the degree of synchronization movements of persons in the group.

  11. Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking

    Armstrong J. W.

    2006-01-01

    Full Text Available This paper discusses spacecraft Doppler tracking, the current-generation detector technology used in the low-frequency (~millihertz gravitational wave band. In the Doppler method the earth and a distant spacecraft act as free test masses with a ground-based precision Doppler tracking system continuously monitoring the earth-spacecraft relative dimensionless velocity $2 Delta v/c = Delta u/ u_0$, where $Delta u$ is the Doppler shift and $ u_0$ is the radio link carrier frequency. A gravitational wave having strain amplitude $h$ incident on the earth-spacecraft system causes perturbations of order $h$ in the time series of $Delta u/ u_0$. Unlike other detectors, the ~1-10 AU earth-spacecraft separation makes the detector large compared with millihertz-band gravitational wavelengths, and thus times-of-flight of signals and radio waves through the apparatus are important. A burst signal, for example, is time-resolved into a characteristic signature: three discrete events in the Doppler time series. I discuss here the principles of operation of this detector (emphasizing transfer functions of gravitational wave signals and the principal noises to the Doppler time series, some data analysis techniques, experiments to date, and illustrations of sensitivity and current detector performance. I conclude with a discussion of how gravitational wave sensitivity can be improved in the low-frequency band.

  12. Doppler Monitoring of the WASP-47 Multiplanet System

    Dai, Fei; Arriagada, Pamela; Butler, R Paul; Crane, Jeffrey D; Johnson, John Asher; Shectman, Stephen A; Teske, Johanna K; Thompson, Ian B; Vanderburg, Andrew; Wittenmyer, Robert A

    2015-01-01

    We present precise Doppler observations of WASP-47, a transiting planetary system featuring a hot Jupiter with both inner and outer planetary companions. This system has an unusual architecture and also provides a rare opportunity to measure planet masses in two different ways: the Doppler method, and the analysis of transit-timing variations (TTV). Based on the new Doppler data, obtained with the Planet Finder Spectrograph on the Magellan/Clay 6.5m telescope, the mass of the hot Jupiter is $370 \\pm 29~M_{\\oplus}$. This is consistent with the previous Doppler determination as well as the TTV determination. For the inner planet WASP-47e, the Doppler data lead to a mass of $12.2\\pm 3.7~ M_{\\oplus}$, in agreement with the TTV-based upper limit of $<$22~$M_{\\oplus}$ ($95\\%$ confidence). For the outer planet WASP-47d, the Doppler mass constraint of $10.4\\pm 8.4~M_{\\oplus}$ is consistent with the TTV-based measurement of $15.2^{+6.7}_{-7.6}~ M_{\\oplus}$.

  13. Measuring Solar Doppler Velocities in the He ii 30.38 nm Emission Using the EUV Variability Experiment (EVE)

    Chamberlin, P. C.

    2016-08-01

    The EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory has provided unprecedented measurements of the solar EUV irradiance at high temporal cadence with good spectral resolution and range since May 2010. The main purpose of EVE was to connect the Sun to the Earth by providing measurements of the EUV irradiance as a driver for space weather and Living With a Star studies, but after launch the instrument has demonstrated the significance of its measurements in contributing to studies looking at the sources of solar variability for pure solar physics purposes. This paper expands upon previous findings that EVE can in fact measure wavelength shifts during solar eruptive events and therefore provide Doppler velocities for plasma at all temperatures throughout the solar atmosphere from the chromosphere to hot flaring temperatures. This process is not straightforward as EVE was not designed or optimized for these types of measurements. In this paper we describe the many detailed instrumental characterizations needed to eliminate the optical effects in order to provide an absolute baseline for the Doppler shift studies. An example is given of a solar eruption on 7 September 2011 (SOL2011-09-07), associated with an X1.2 flare, where EVE Doppler analysis shows plasma ejected from the Sun in the He ii 30.38 nm emission at a velocity of almost 120 km s^{-1} along the line-of-sight.

  14. Parametric Explosion Spectral Model

    Ford, S R; Walter, W R

    2012-01-19

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.

  15. Photovoltaic spectral responsivity measurements

    Emery, K.; Dunlavy, D.; Field, H.; Moriarty, T. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    This paper discusses the various elemental random and nonrandom error sources in typical spectral responsivity measurement systems. The authors focus specifically on the filter and grating monochrometer-based spectral responsivity measurement systems used by the Photovoltaic (PV) performance characterization team at NREL. A variety of subtle measurement errors can occur that arise from a finite photo-current response time, bandwidth of the monochromatic light, waveform of the monochromatic light, and spatial uniformity of the monochromatic and bias lights; the errors depend on the light source, PV technology, and measurement system. The quantum efficiency can be a function of he voltage bias, light bias level, and, for some structures, the spectral content of the bias light or location on the PV device. This paper compares the advantages and problems associated with semiconductor-detector-based calibrations and pyroelectric-detector-based calibrations. Different current-to-voltage conversion and ac photo-current detection strategies employed at NREL are compared and contrasted.

  16. Doppler radar retrievals from lava fountaining paroxysms generating tephra plumes at Mt. Etna

    Valentin, Freret-Lorgeril; Franck, Donnadieu; Mauro, Coltelli; Simona, Scollo; Patrick, Fréville; Claude, Hervier; Michele, Prestifilippo

    2016-04-01

    Etna volcano is one of the most active European volcanoes. Between January 2011 and December 2013, a new crater called the New South East Crater (NSEC) was built during 46 eruptive episodes characterized by lava fountaining generating tephra plumes that reached up to 10 km (a.s.l). A 23 cm-wavelength Doppler radar (VOLDORAD 2B), located about 3 km from NSEC at the Montagnola station and integrated into the INGV-OE instrumental network, has been continuously monitoring the explosive activity of Mt. Etna's summit craters since 2009. We have studied these paroxysms by analyzing the radar echoes and Doppler signals coming from adjacent volumes of the fixed beam probing the lava fountains close to the eruptive crater, in combination with thermal and visible imagery. The range gating (150 m-deep probed volumes along-beam) allows us to discriminate the active summit craters and to roughly estimate the lava fountain width. The backscattered power, which is related to the erupted tephra mass load in the beam, and Doppler velocities help to mark the transition from Strombolian activity to lava fountaining, providing onset and end times of the fountain. Both radar parameters directly provide a proxy for the mass eruption rate, which is found to follow the time variations of tephra plume height. Oscillations of the echo power during lava fountaining indicate a pulsatile behavior likely originating in the magmatic conduit or deeper reservoir. Ejection velocities retrieved from positive along-beam velocities measured near the emission source, are found to range from 140 to almost 350 m/s during the climax. Maximum along-beam Doppler velocity components from fallouts allow us to infer maximum particle sizes (pluri-decimetric) in agreement with field observations. The mode of power spectral distribution could further be used to constrain the mean diameter of proximal fallout. A reliable quantification of the source mass loading parameters requires more stringent constraints on the

  17. Effect of non-linearity in predicting doppler waveforms through a novel model

    Sengupta Amit

    2003-09-01

    Full Text Available Abstract Background In pregnancy, the uteroplacental vascular system develops de novo locally in utero and a systemic haemodynamic & bio-rheological alteration accompany it. Any abnormality in the non-linear vascular system is believed to trigger the onset of serious morbid conditions like pre-eclampsia and/or intrauterine growth restriction (IUGR. Exact Aetiopathogenesis is unknown. Advancement in the field of non-invasive doppler image analysis and simulation incorporating non-linearities may unfold the complexities associated with the inaccessible uteroplacental vessels. Earlier modeling approaches approximate it as a linear system. Method We proposed a novel electrical model for the uteroplacental system that uses MOSFETs as non-linear elements in place of traditional linear transmission line (TL model. The model to simulate doppler FVW's was designed by including the inputs from our non-linear mathematical model. While using the MOSFETs as voltage-controlled switches, a fair degree of controlled-non-linearity has been introduced in the model. Comparative analysis was done between the simulated data and the actual doppler FVW's waveforms. Results & Discussion Normal pregnancy has been successfully modeled and the doppler output waveforms are simulated for different gestation time using the model. It is observed that the dicrotic notch disappears and the S/D ratio decreases as the pregnancy matures. Both these results are established clinical facts. Effects of blood density, viscosity and the arterial wall elasticity on the blood flow velocity profile were also studied. Spectral analysis on the output of the model (blood flow velocity indicated that the Total Harmonic Distortion (THD falls during the mid-gestation. Conclusion Total harmonic distortion (THD is found to be informative in determining the Feto-maternal health. Effects of the blood density, the viscosity and the elasticity changes on the blood FVW are simulated. Future works are

  18. CLINIC O RADIOLOGICAL EVALUATION OF GYNECOLOGICAL NEOPLASM S BY USG AND COLOUR DOPPLER

    Avadhesh Pratap

    2015-09-01

    Full Text Available BACKGROUND : Gynecological neoplasm s is one of the major causes of morbidity and mortality in females especially in peri and postmenopausal women. Ultrasonography (Both TAS & TVS is the method of choice for examining the female pelvis and it is the principle imaging modality in the evaluation of gynecological diseases. Duplex study with color flow mapping helps in assessment of vascularity of structure. AIMS AND OBJECTIVE: Ev aluating the efficacy of color and spectral Doppler in the diagnosis of gynecological neoplasm s with histopathology as the reference. STUDY SETTING AND DE SIGN: A prospective study of 50 patients was done in the department of Radio diagnosis, in association with Department of Obstetrics and Gynecology and Department of Pathology. Age, Sex, Address, Registration number was recorded in a proforma specially prepared for the purpose of our study & a brief note on presenting complaints. Any significant past histor y if present was noted. Significant, general, systemic & gynecological examination including P/A, P/S and P/V was done. MATERIALS AND METHOD S: All patients of strong clinical suspicion of Gynecological neoplasm s were taken as study subject. Patients were ex amined by real time Ultrasonography and color Doppler (GE - LOGIQ 3 Expert and Siemens - Sonoline 50 with convex, low frequency (2 - 5MHz transducer by trans - abdominal and medium frequency (5 - 7MHz transducer by trans - vaginal route. RESULT: Most of the benign neoplasm’s were seen before 50 years of age and most common presenting symptom in the present study was pain in abdomen (62%. Among 50 patients, 24(48% were of benign and 26(52% were of malignant neoplasm. Most common clinical diagnosis was pelvic mass (22% and ovarian mass (22%. Out of 50 cases, 24(48% were benign and 26(52% were malignant neoplasm. In this study 85.72% of malignant ovarian tumors had PI value <0.8 in contrast to only 50% of benign ovarian tumors. In the same way 85.72% of malignan

  19. Analysis of airborne Doppler lidar, Doppler radar and tall tower measurements of atmospheric flows in quiescent and stormy weather

    Bluestein, H. B.; Doviak, R. J.; Eilts, M. D.; Mccaul, E. W.; Rabin, R.; Sundara-Rajan, A.; Zrnic, D. S.

    1986-01-01

    The first experiment to combine airborne Doppler Lidar and ground-based dual Doppler Radar measurements of wind to detail the lower tropospheric flows in quiescent and stormy weather was conducted in central Oklahoma during four days in June-July 1981. Data from these unique remote sensing instruments, coupled with data from conventional in-situ facilities, i.e., 500-m meteorological tower, rawinsonde, and surface based sensors, were analyzed to enhance understanding of wind, waves and turbulence. The purposes of the study were to: (1) compare winds mapped by ground-based dual Doppler radars, airborne Doppler lidar, and anemometers on a tower; (2) compare measured atmospheric boundary layer flow with flows predicted by theoretical models; (3) investigate the kinematic structure of air mass boundaries that precede the development of severe storms; and (4) study the kinematic structure of thunderstorm phenomena (downdrafts, gust fronts, etc.) that produce wind shear and turbulence hazardous to aircraft operations. The report consists of three parts: Part 1, Intercomparison of Wind Data from Airborne Lidar, Ground-Based Radars and Instrumented 444 m Tower; Part 2, The Structure of the Convective Atmospheric Boundary Layer as Revealed by Lidar and Doppler Radars; and Part 3, Doppler Lidar Observations in Thunderstorm Environments.

  20. Spectral library searching in proteomics.

    Griss, Johannes

    2016-03-01

    Spectral library searching has become a mature method to identify tandem mass spectra in proteomics data analysis. This review provides a comprehensive overview of available spectral library search engines and highlights their distinct features. Additionally, resources providing spectral libraries are summarized and tools presented that extend experimental spectral libraries by simulating spectra. Finally, spectrum clustering algorithms are discussed that utilize the same spectrum-to-spectrum matching algorithms as spectral library search engines and allow novel methods to analyse proteomics data. PMID:26616598