Готові списки джерел за темами / Spectral Doppler analysis

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Добірка наукової літератури з теми "Spectral Doppler analysis"

Автор: Grafiati

Опубліковано: 10 березня 2023

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Статті в журналах з теми "Spectral Doppler analysis"

Parkinson, M. L., K. M. Hannah, and P. L. Dyson. "Complexity in the high latitude HF radar spectral width boundary region." Annales Geophysicae 26, no. 4 (May 13, 2008): 877–92. http://dx.doi.org/10.5194/angeo-26-877-2008.

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Abstract. SuperDARN radars are sensitive to the collective Doppler characteristics of decametre-scale irregularities in the high latitude ionosphere. The radars routinely observe a distinct transition from large spectral width (>100 m s−1) located at higher latitudes to low spectral width (<50 m s−1) located at lower latitudes. Because of its equatorward location, the TIGER Tasmanian radar is very sensitive to the detection of the spectral width boundary (SWB) in the nightside auroral ionosphere. An analysis of the line-of-sight velocities and 2-D beam-swinging vectors suggests the meso-scale (~100 km) convection is more erratic in the high spectral width region, but slower and more homogeneous in the low spectral width region. The radar autocorrelation functions are better modelled using Lorentzian Doppler spectra in the high spectral width region, and Gaussian Doppler spectra in the low spectral width region. However, paradoxically, Gaussian Doppler spectra are associated with the largest spectral widths. Application of the Burg maximum entropy method suggests the occurrence of double-peaked Doppler spectra is greater in the high spectral width region, implying the small-scale (~10 km) velocity fluctuations are more intense above the SWB. These observations combined with collective wave scattering theory imply there is a transition from a fast flowing, turbulent plasma with a correlation length of velocity fluctuations less than the scattering wavelength, to a slower moving plasma with a correlation length greater than the scattering wavelength. Peak scaling and structure function analysis of fluctuations in the SWB itself reveals approximately scale-free behaviour across temporal scales of ~10 s to ~34 min. Preliminary scaling exponents for these fluctuations, αGSF=0.18±0.02 and αGSF=0.09±0.01, are even smaller than that expected for MHD turbulence.

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Hayashi, Nobuharu, Yukio Miyamoto, Norio Nakata, Takeo Irie, Masahiro Ikegami, Keiko Asao, and Shimpei Tada. "Breast masses: Color Doppler, power Doppler, and spectral analysis findings." Journal of Clinical Ultrasound 26, no. 5 (June 1998): 231–38. http://dx.doi.org/10.1002/(sici)1097-0096(199806)26:5<231::aid-jcu1>3.0.co;2-d.

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Chaxel, Y., E. M. Griffin, and N. P. Meredith. "Spectral analysis techniques for doppler lidar measurements." Advances in Space Research 21, no. 10 (January 1998): 1441–44. http://dx.doi.org/10.1016/s0273-1177(97)00657-1.

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Anandan, V. K., C. J. Pan, T. Rajalakshmi, and G. Ramachandra Reddy. "Multitaper spectral analysis of atmospheric radar signals." Annales Geophysicae 22, no. 11 (November 29, 2004): 3995–4003. http://dx.doi.org/10.5194/angeo-22-3995-2004.

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Abstract. Multitaper spectral analysis using sinusoidal taper has been carried out on the backscattered signals received from the troposphere and lower stratosphere by the Gadanki Mesosphere-Stratosphere-Troposphere (MST) radar under various conditions of the signal-to-noise ratio. Comparison of study is made with sinusoidal taper of the order of three and single tapers of Hanning and rectangular tapers, to understand the relative merits of processing under the scheme. Power spectra plots show that echoes are better identified in the case of multitaper estimation, especially in the region of a weak signal-to-noise ratio. Further analysis is carried out to obtain three lower order moments from three estimation techniques. The results show that multitaper analysis gives a better signal-to-noise ratio or higher detectability. The spectral analysis through multitaper and single tapers is subjected to study of consistency in measurements. Results show that the multitaper estimate is better consistent in Doppler measurements compared to single taper estimates. Doppler width measurements with different approaches were studied and the results show that the estimation was better in the multitaper technique in terms of temporal resolution and estimation accuracy.

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Herment, A., and J. F. Giovannelli. "An Adaptive Approach to Computing the Spectrum and Mean Frequency of Doppler Signals." Ultrasonic Imaging 17, no. 1 (January 1995): 1–26. http://dx.doi.org/10.1177/016173469501700101.

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Modern ultrasound Doppler systems are facing the problem of processing increasingly shorter data sets. Spectral analysis of the strongly nonstationary Doppler signal needs to shorten the analysis window while maintaining a low variance and high resolution spectrum. Color flow imaging requires estimation of the Doppler mean frequency from even shorter Doppler data sets to obtain both a high frame rate and high spatial resolution. We reconsider these two estimation problems in light of adaptive methods. A regularized parametric method for spectral analysis as well as an adapted mean frequency estimator are developed. The choice of the adaptive criterion is then addressed and adaptive spectral and mean frequency estimators are developed to minimize the mean square error on estimation in the presence of noise. Two suboptimal spectral and mean-frequency estimators are then derived for real-time applications. Finally, their performance is compared to that of both the FFT based periodogram and the AR parametric spectral analysis for the spectral estimator, and, to both the correlation angle and the Kristoffersen's [8] estimators for the mean frequency estimator using Doppler data recorded in vitro.

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Burns, Peter N. "The physical principles of Doppler and spectral analysis." Journal of Clinical Ultrasound 15, no. 9 (November 1987): 567–90. http://dx.doi.org/10.1002/jcu.1870150903.

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Mahieddine, Latfaoui, and Bereksi Reguig Fethi. "Time Frequency Analysis of Femoral Doppler Ultrasound Signals by AR Modelling." Applied Mechanics and Materials 302 (February 2013): 319–25. http://dx.doi.org/10.4028/www.scientific.net/amm.302.319.

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In this study, we have compared the efficiency of the short time Fourier transform (STFT) and autoregressive modelling (AR) and autoregressive moving average (ARMA) of the femoral Doppler artery ultrasonic signals, in order to determine the spectral broadening index (SBI). Our aim is to detect the impact of the two modelling approaches on sonograms and of power spectral density- frequency diagrams obtained from femoral arterial Doppler Signals. The sonograms have been then used to compare the methods in terms of their frequency resolution and effects in determining the stenosis of femoral artery. In this paper we have used generated frequency envelopes from the Doppler spectrum to determine an index showing the degree of severity of stenosis cases. This index called broadening spectral index is calculated for various real cases.

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Formosa, Cynthia, Christian Ellul, Anabelle Mizzi, Stephen Mizzi, and Alfred Gatt. "Interrater Reliability of Spectral Doppler Waveform." Journal of the American Podiatric Medical Association 108, no. 4 (July 1, 2018): 280–84. http://dx.doi.org/10.7547/16-026.

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Background: Spectral Doppler ultrasound examination of pedal arteries is one of the most frequently used noninvasive assessment methods by health-care professionals for the diagnosis and ongoing monitoring of people at risk for or living with peripheral arterial disease. The aim of this study was to determine the interrater reliability of the interpretation of spectral Doppler waveform analysis. Methods: An interrater reliability study was conducted among five experienced podiatric physicians at the University of Malta Research Laboratory (Msida, Malta). A researcher who was not a rater in this study randomly selected 229 printed spectral Doppler waveforms from a database held at the University of Malta. Each rater independently rated the qualitative spectral waveforms. Results: Interrater reliability of the spectral Doppler waveform interpretation was excellent among the five experienced podiatric physicians (α = 0.98). The intraclass correlation coefficient showed a high degree of correlation in waveform interpretation across raters (P < .001). Conclusions: This study demonstrates high interrater reliability in visual spectral Doppler interpretation among experienced clinicians. The current foot screening guidelines do not refer to spectral Doppler waveform analysis in their recommendations, which has been shown in studies to be an important modality for the diagnosis of peripheral arterial disease when ankle-brachial pressure indexes are falsely elevated in calcified arteries. If interpreted correctly, the information obtained can provide an indication of the presence of peripheral arterial disease and facilitate early management of this condition.

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Sheppard, Brian E., Merhala Thurai, Peter Rodriguez, Patrick C. Kennedy, and David R. Hudak. "Improved Precipitation Typing Using POSS Spectral Modal Analysis." Journal of Atmospheric and Oceanic Technology 38, no. 3 (March 2021): 537–54. http://dx.doi.org/10.1175/jtech-d-20-0075.1.

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AbstractThe Precipitation Occurrence Sensor System (POSS) is a small X-band Doppler radar that measures the Doppler velocity spectra from precipitation falling in a small volume near the sensor. The sensor records a 2D frequency of occurrence matrix of the velocity and power at the mode of each spectrum measured over 1 min. The centroid of the distribution of these modes, along with other spectral parameters, defines a data vector input to a multiple discriminant analysis (MDA) for classification of the precipitation type. This requires the a priori determination of a training set for different types, particle size distributions (PSDs), and wind speed conditions. A software model combines POSS system parameters, a particle scattering cross section, and terminal velocity models, to simulate the real-time Doppler signal measured by the system for different PSDs and wind speeds. This is processed in the same manner as the system hardware to produce bootstrap samples of the modal centroid distributions for the MDA training set. MDA results are compared to images from the Multi-Angle Snowflake Camera (MASC) at the MASCRAD site near Easton, Colorado, and to the CSU–CHILL X-band radar observations from Greeley, Colorado. In the four case studies presented, POSS successfully identified precipitation transitions through a range of types (rain, graupel, rimed dendrites, aggregates, unrimed dendrites). Also two separate events of hail were reported and confirmed by the images.

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Gergely, Mathias, Maximilian Schaper, Matthias Toussaint, and Michael Frech. "Doppler spectra from DWD's operational C-band radar birdbath scan: sampling strategy, spectral postprocessing, and multimodal analysis for the retrieval of precipitation processes." Atmospheric Measurement Techniques 15, no. 24 (December 20, 2022): 7315–35. http://dx.doi.org/10.5194/amt-15-7315-2022.

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Abstract. This study explores the potential of using Doppler (power) spectra from vertically pointing C-band radar birdbath scans to investigate precipitating clouds above the radar. First, the new birdbath scan strategy for the network of dual-polarization C-band radars operated by the German Meteorological Service (Deutscher Wetterdienst, DWD) is outlined, and a novel spectral postprocessing and analysis method is presented. The postprocessing algorithm isolates the weather signal from non-meteorological contributions in the radar output based on polarimetric attributes, identifies the statistically significant precipitation modes contained in each Doppler spectrum, and calculates characteristics of every precipitation mode as well as multimodal properties that describe the relation among different modes when more than a single mode is identified. To achieve a high degree of automation and flexibility, the postprocessing chain combines classical signal processing with clustering algorithms. Uncertainties in the calculated modal and multimodal properties are estimated from the small variations associated with smoothing the measured radar signal. The analysis of five birdbath scans recorded at different radar sites and for various precipitation conditions delivers reliable profiles of the derived modal and multimodal properties for two snowfall cases and for stratiform precipitation above and below the melting layer. To help identify the dominant precipitation growth mechanism, Doppler spectra from DWD's birdbath scans can be used to retrieve the typical degree of riming for individual snow modes. Here, the automatically identified snow modes span a wide range of riming conditions with estimated rime mass fractions (RMFs) of up to RMF>0.5. The evaluation of Doppler spectra inside the melting layer and for an intense frontal shower, with observed radar reflectivities of up to about 40 dBZ, occasionally shows erroneously identified precipitation modes and spurious results for the calculated higher-order Doppler moments of skewness and kurtosis. Nonetheless, the Doppler spectra from DWD's operational C-band radar birdbath scan provide a detailed view into the precipitating clouds and allow for calculating a high-resolution profile of radar reflectivity, mean Doppler velocity, and spectral width even in intense frontal precipitation.

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Дисертації з теми "Spectral Doppler analysis"

Fan, Lingke. "Spectral and time-frequency analysis of ultrasonic Doppler signals." Thesis, University of Leicester, 1994. http://hdl.handle.net/2381/34342.

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Spectral analysis of Doppler signals plays a very important role in non-invasive measurements of blood velocity distributions. Among the various spectral analysis methods available, the fast Fourier transform (FFT) is regarded as a "traditional" spectral analysis tool and is widely used in commercial, clinical, experimental and research equipment. Some drawbacks of this method, however, have imposed limitations on its use in some clinical cases. A numbers of spectral and time-frequency analysis methods have been studied in this dissertation. These include the traditional FFT, the autoregressive (AR) method, the Wigner-Ville distribution (WVD), and the Choi-Williams distribution (CWD). The advantages and disadvantages of each method have been studied and summarised. Efforts have been made to improve the temporal and frequency resolution of the results. New analysis methods such as the WVD and CWD have been interpreted physically, and some of their new properties have been explored. The results have suggested that the heights of the peaks in the AR spectra of narrow-band signals are not necessarily proportional to signal power, and should be used with caution in the context of Doppler signal processing. The results have also shown that it is appropriate to use the WVD or CWD to analyse signals when high temporal resolution is required. In practice, it is easier for the operator to handle the WVD, which usually produces reasonably good results. The above methods have been applied in practice. Considerable software and hardware development has been carried out, and a number of analysers have been implemented for use under different practical conditions. These analysers were also used to compare experimentally the analysis methods mentioned above, and to confirm the results of theoretical analyses. Some of these analysers have found applications in clinical practice.

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David, Jean-Yves. "Modern spectral analysis techniques for blood flow velocity and spectral measurements with a 20 MHZ pulsed doppler ultrasound catheter." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/17791.

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Sukkar, Ibrahim Hassan. "Non-invasive ultrasound Doppler spectral analysis in the assessment of aorto-iliac stenotic disease." Thesis, Imperial College London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299172.

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Graça, Cristo dos Santos Lopes Ruano Maria da. "Investigation of real-time spectral analysis techniques for use with pulsed ultrasonic Doppler blood flow detectors." Thesis, Bangor University, 1992. https://research.bangor.ac.uk/portal/en/theses/investigation-of-realtime-spectral-analysis-techniques-for-use-with-pulsed-ultrasonic-doppler-blood-flow-detectors(f184d2a8-bde7-492a-b487-438704d3ea04).html.

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The goals of the work described here were the development of a method of selection of spectral estimation for use with pulsed Doppler ultrasonic blood flow instruments, and the use of this method to select an estimator and its implementation in a form suitable for real-time applications. A study of estimation accuracy of the mean frequency and bandwidth using a number of spectral estimators was carried out. Fourier based, parametric, and, minimum variance estimators were considered. A Doppler signal simulator was developed to allow the accuracy tests required. A method of selection of spectral estimators based on the accuracy of estimation of decisive signal parameters, under the constraint of low computational complexity has been proposed. This novel cost/benefit criterion, allows the possibility of weighting appropriate to estimator (mean frequency and bandwidth) and signal frequency importance (across the range of signal characteristics). For parametric spectral estimators, this criterion may also be used to select model order, leading to lower orders than FPE, AIC and CAT criteria. Its use led to the selection of a 4t' order modified covariance parametric method. A new version of the modified covariance method for spectral estimation of real signals was developed. This was created with a view to the parallel partitioning of the algorithm for parallel implementation on a transputer-based system, using OCCAM. A number of parallel topologies were implemented. Their performance was evaluated considering estimation of a single, and a sequence of Doppler signal segments, revealing the feasibility of these parallel implementations to be achieved in real-time.

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Yu, Yonghui. "MODEL STUDIES OF TIME-DEPENDENT DUCTING FOR HIGH-FREQUENCY GRAVITY WAVES AND ASSOCIATED AIRGLOW RESPONSES IN THE UPPER ATMOSPHER." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3623.

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This doctoral dissertation has mainly concentrated on modeling studies of shorter period acoustic-gravity waves propagating in the upper atmosphere. Several cases have been investigated in the literature, which are focusing on the propagation characteristics of high-frequency gravity wave packets. The dissertation consists of five main divisions of which each has its own significance to be addressed, and these five chapters are also bridged in order with each other to present a theme about gravity wave ducting dynamics, energetics, and airglows. The first chapter is served as an introduction of the general topic about atmospheric acoustic-gravity waves. Some of the historical backgrounds are provided as an interesting refreshment and also as a motivation reasoning this scientific research for decades. A new 2-D, time-dependent, and nonlinear model is introduced in the second chapter (the AGE-TIP model, acronymically named atmospheric gravity waves for the Earth plus tides and planetary waves). The model is developed during this entire doctoral study and has carried out almost all research results in this dissertation. The third chapter is a model application for shorter period gravity waves ducted in a thermally stratified atmosphere. In spite of mean winds the thermal ducting occurs because ducted waves are fairly common occurrences in airglow observations. One-dimensional Fourier analysis is applied to identify the ducted wave modes that reside within multiple thermal ducts. Besides, the vertical energy flux and the wave kinetic energy density are derived as wave diagnostic variables to better understand the time-resolved vertical transport of wave energy in the presence of multiple thermal ductings. The fourth chapter is also a model application for shorter period gravity waves, but it instead addresses the propagation of high-frequency gravity waves in the presence of mean background wind shears. The wind structure acts as a significant directional filter to the wave spectra and hence causes noticeable azimuthal variations at higher altitudes. In addition to the spectral analysis applied previously the wave action has been used to interpret the energy coupling between the waves and the mean flow among some atmospheric regions, where the waves are suspected to extract energy from the mean flow at some altitudes and release it to other altitudes. The fifth chapter is a concrete and substantial step connecting theoretical studies and realistic observations through nonlinearly coupling wave dynamic model with airglow chemical reactions. Simulated O (1S) (557.7 nm) airglow images are provided so that they can be compared with observational airglow images. These simulated airglow brightness variations response accordingly with minor species density fluctuations, which are due to propagating and ducting nonlinear gravity waves within related airglow layers. The thermal and wind structures plus the seasonal and geographical variabilities could significantly influence the observed airglow images. By control modeling studies the simulations can be used to collate with concurrent observed data, so that the incoherencies among them could be very useful to discover unknown physical processes behind the observed wave scenes.
Ph.D.
Department of Physics
Sciences
Physics PhD

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Kahyaoglu, Nazli Deniz. "Spectral And Statistical Analyses Of Experimental Radar Clutter Data." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612799/index.pdf.

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The performance of radar detection and imaging systems strongly depends on the characteristics of radar clutter. In order to improve the radar signal processing algorithms, successful analysis and modeling of radar clutter are required. For a successful model of radar clutter, both the spectral and statistical characteristics of the clutter should be revealed. Within the scope of this study, an experimental radar data acquisition system is established to analyze radar clutter. The hardware and the data processing system are first verified using generic signals and then a set of measurements is taken in the open terrain. In this thesis, the limitations and problems encountered during the establishment of the system are explained in detail. The spectral and statistical analyses performed on the recorded data are examined. The temporal and spatial behavior of the measured clutter data are explored. The hypothetical models proposed so far in the literature are tested on the experimental data and the fitting of models to the experimental data is confirmed using various goodness-of-fit tests. Finally, the results of the analyses are interpreted in the light of the radar system parameters and the characteristics of the illuminated terrain.

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Marques, Márcia Talita Amorim. "Obtenção da altura da camada limite planetária através da análise espectral do campo de vento do lidar Doppler." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-23022018-092958/.

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Este estudo explora a obtenção da altura da camada limite planetária a partir de diferentes métodos e equipamentos, com foco na análise espectral do campo de vento do lidar Doppler. Realizou-se uma campanha de medição por 80 dias com dois lidars Dopplers comerciais com diferentes alcances verticais. Para o lidar com maior alcance vertical e consequetemente uma medida direta da altura da camada limite planetária, foi aplicado o método da variância da razão sinal-ruído e os resultados foram comparados aos valores de altura estimados a partir de dados de radiossondagem através de dois métodos distintos, o método da parcela e o método do número de Richardson bulk, o qual apresentou melhores resultados. Para o lidar com menor alcance vertical, aplicou-se a análise espectral que forneceu valores de comprimento de onda dos picos espectrais, proporcionais à altura da camada limite planetária. A constante de proporcionalidade para obtenção dos valores da altura da camada foi calculada comparando-se os resultados aos valores de altura estimados pela radiossondagem através do método do número de Richardson bulk, obtendo-se um valor de constante de proporcionalidade próximo ao sugerido na literatura. Entretanto, o conjunto de dados que mostrou boas estimativas dos picos espectrais foi bastante restrito, limitando a comparação ao longo do período entre os lidars.
This study explores the obtaining of the planetary boundary layer height through different methods and equipment, focusing on the spectral analysis of the wind field from Doppler lidar. An 80-day measurement campaign was conducted with two commercial Doppler lidars with different vertical ranges. For the lidar with greater vertical range and consequently a direct measurement of the planetary boundary layer heigth, the method of signal-to-noise ratio variance was applied and the results were compared to the height values estimated from radiosonding data using two different methods, the parcel method and the bulk Richardson number method, which presented better results. For the lidar with a lower vertical range, spectral analysis was applied, which provided wavelength values of the spectral peak, proportional to the planetary boundary layer height. The proportionality constant, in order to obtain the boundary height values, were calculated by comparing the height values estimated from the radiosonding data, using the bulk Richardson number method. Proportionality constant value close to the one found in the literature were obtained. However, the set of data that showed good estimates of the spectral peaks was very restricted, limiting the comparison over the period between the lidars.

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Himes, Benjamin John. "Development and Analysis of a Vibration Based Sleep Improvement Device." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/9168.

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Many research studies have analyzed the effect that whole-body vibration (WBV) has on sleep, and some have sought to use vibration to treat sleep disorders such as insomnia. It has been shown that low frequencies (f < 2Hz) are generally sleep inducing, but oscillations of this frequency are typically difficult to achieve using electromagnetic vibration drives. In the research that has been performed, optimal vibration parameters have not been determined, and the effects of multiple vibration sources vibrating at different frequencies to induce a low frequency traveling wave have not been explored. Insomnia affects millions of people worldwide, and non-pharmacological treatment options are limited. A bed excited with multiple vibration sources was used to explore beat frequency vibration as a non-pharmacological treatment for insomnia. A repeated measures design pilot study of 14 participants with mild-moderate insomnia symptom severity was conducted to determine the effects of beat frequency vibration, and traditional standing wave vibration on sleep latency and quality. Participants were monitored using high-density electroencephalography (HD-EEG). Sleep latency was compared between treatment conditions. Trends of a decrease in sleep latency due to beat frequency vibration were found (p ≤ 0.181 for AASM latency, and p ≤ 0.068 for unequivocal sleep latency). Neural complexity during wake, N1, and N2 stages were compared using Multi-Scale Sample Entropy (MSE), which demonstrated significantly lower MSE between wake and N2 stages (p ≤ 0.002). Lower MSE was found in the transition from wake to N1 stage sleep but did not reach significance (p ≤ 0.300). During N2 sleep, beat frequency vibration shows lower MSE than the control session in the left frontoparietal region. This indicates that beat frequency vibration may lead to a decrease of conscious awareness during deeper stages of sleep. Standing wave vibration caused reduced Alpha activity and increased Delta activity during wake. Beat frequency vibration caused increased Delta activity during N2 sleep. These preliminary results suggest that beat frequency vibration may help individuals with insomnia symptoms by decreasing sleep latency, by reducing their conscious awareness, and by increasing sleep drive expression during deeper stages of sleep. Standing wave vibration may be beneficial for decreasing expression of arousal and increasing expression of sleep drive during wake, implying that a dynamic vibration treatment may be beneficial. The application of vibration treatment as part of a heuristic sleep model is discussed.

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Ho, King-fung. "Some studies in deconvoluting Coincidence Doppler Broadening spectra /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23621953.

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Kurt, Mustafa. "Time Resolved Spectroscopy Of Laser Induced Air Plasma." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608985/index.pdf.

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The laser beam interaction with matter and the plasma generation have been studied for many years. In some applications what is really important is to understand the composition and the temporal evolution of the species in the interested medium. In this thesis, time resolved optical spectroscopy was employed to understand the evolution of the plasma which is produced by interaction of Infrared (1.064 µ
m) laser beam with air. In this thesis, a new technique is suggested to analyze the time evolution of laser induced breakdown spectroscopy. The suggested method and the instrumentation of the setup are tested with a single gas (He). After the tests, we analyzed time sequence spectra of Laser Induced Air Breakdown. The suggested method is based on triggering the laser and the spectrometer at different time and applying the spectrometer trigger time by adding the time delay (&
#916
t) between them by using the pulse generator. The results show that the decay rates are slowing down microseconds after the excitation of the plasma. The results of the time-resolved measurements of the line spectra show that different component of the air has different decay rate, and lifetime. The lifetime of helium is 20 µ
s, and the decay start 5 µ
s after the initiation of plasma. Air has 12 µ
s lifetime, and the decay start 3 µ
s after the initiation of the plasma. Also, the decay rate and the lifetime depend on the state. We also calculate Doppler velocity for different component and different emission states. Doppler velocities show that the component which has great mass has small velocity, the component which has small mass has high velocity.

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Книги з теми "Spectral Doppler analysis"

Katō, Hajime. Doppler-free high resolution spectral atlas of iodine molecule 15 000 to 19 000 cm⁻¹. Japan: Japan Society for the Promotion of Science, 2000.

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Jonggil, Lee, and United States. National Aeronautics and Space Administration. Scientific and Technical Information Program., eds. The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1991.

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Baxa, Ernest G. The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar. Hampton, Va: Langley Research Center, 1991.

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United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., ed. Spectrum modal analysis for the detection of low-altitude indshear with airborne Doppler radar. [Washington, DC]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1992.

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United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., ed. Spectrum modal analysis for the detection of low-altitude windshear with airborne Doppler radar. [Washington, DC]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1992.

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Choi, Seong Jong. Parametric spectral analysis of ultrasound doppler signal. 1992.

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The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1991.

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Davila, Jesse. Aberration and angle-dependent Doppler effects on the spectra of two component accretion column x-ray pulsars. 1995.

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Частини книг з теми "Spectral Doppler analysis"

Maulik, Dev. "Spectral Doppler Sonography: Waveform Analysis and Hemodynamic Interpretation." In Doppler Ultrasound in Obstetrics & Gynecology, 43–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-86441-4_4.

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Maulik, Dev. "Spectral Doppler Sonography: Waveform Analysis and Hemodynamic Interpretation." In Doppler Ultrasound in Obstetrics and Gynecology, 39–61. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-06189-9_4.

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Tworzydlo, P., and A. D. C. Chan. "Spectral Analysis of Respiratory and Cardiac Signals Using Doppler Radar." In IFMBE Proceedings, 1034–38. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19387-8_252.

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Arbeille, Ph, F. Lapierre, F. Patat, M. Berson, D. Besse, and L. Pourcelot. "Quantification of carotid stenosis using continuous wave Doppler and spectral analysis." In Developments in Cardiovascular Medicine, 179–92. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-4305-6_12.

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Gömöry, P., J. Rybák, A. Kučera, W. Curdt, and H. Wöhl. "Analysis of Doppler Shifts of Spectral Lines Obtained by the CDS/SOHO Instrument." In Solar Magnetic Phenomena, 203–6. Dordrecht: Springer Netherlands, 2005. http://dx.doi.org/10.1007/1-4020-2962-4_16.

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D’Addio, G., M. Cesarelli, P. Bifulco, L. Iuppariello, G. Faiella, D. Lapi, and A. Colantuoni. "Effects of Wavelets Analysis on Power Spectral Distributions in Laser Doppler Flowmetry Time Series." In IFMBE Proceedings, 647–50. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-00846-2_160.

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Robertson, Patrick, and Stefan Kaiser. "Doppler Spread Analysis and Simulation for Multi-Carrier Mobile Radio and Broadcast Systems." In Multi-Carrier Spread Spectrum & Related Topics, 279–86. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/978-1-4615-4463-0_32.

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Pascual, J., T. Cano, F. J. Burgos, C. Cuesta, A. Tato, G. Fernández-Juárez, V. Gómez, L. Orofino, F. Liaño, and J. Ortuño. "Iliac Artery Histology and Renal Allograft Blood Flow Measured by Doppler Spectrum Analysis." In Late Graft Loss, 234. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5434-5_56.

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Merkus, J. W. S., W. N. J. C. van Asten, S. H. Skotnicki, L. B. Hilbrands, A. J. Hoitsma, and R. A. P. Koene. "Haemodynamic changes in human kidney allografts following administration of nifedipine: assessment with doppler spectrum analysis." In Transplant International Official Journal of the European Society for Organ Transplantation, 17–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-77423-2_5.

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Kitabatake, Akira, Jun Tanouchi, Masaaki Uematsu, Yasuji Doi, and Masatsugu Hori. "A Doppler Catheter Technique Using Fast Fourier Spectrum Analysis for the Assessment of Coronary Flow Dynamics." In Regulation of Coronary Blood Flow, 3–10. Tokyo: Springer Japan, 1991. http://dx.doi.org/10.1007/978-4-431-68367-4_1.

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Тези доповідей конференцій з теми "Spectral Doppler analysis"

Campos, Rita, Edite Figueiras, Luis F. Requicha Ferreira, and Anne Humeau-Heurtier. "Spectral analysis of laser Doppler flowmetry signals." In 2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG). IEEE, 2012. http://dx.doi.org/10.1109/enbeng.2012.6331342.

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Giovannelli, J. F., A. Herment, and G. Demoment. "A Bayesian approach to ultrasound Doppler spectral analysis." In 1993 IEEE Ultasonics Symposium. IEEE, 1993. http://dx.doi.org/10.1109/ultsym.1993.339627.

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Mattesini, Paolo, Alessandro Ramalli, Gianluca Goti, Lorena Petrusca, Olivier Basset, Piero Tortoli, and Herve Liebgott. "Spectral Doppler analysis with sparse and full 2-D arrays." In 2019 IEEE International Ultrasonics Symposium (IUS). IEEE, 2019. http://dx.doi.org/10.1109/ultsym.2019.8926013.

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Li, Xiaofei, and Xiaojian Xu. "Doppler spectral analysis for two-dimensional time-evolving nonlinear sea surfaces." In SPIE Defense, Security, and Sensing, edited by Firooz A. Sadjadi, Abhijit Mahalanobis, Steven L. Chodos, William E. Thompson, David P. Casasent, and Tien-Hsin Chao. SPIE, 2010. http://dx.doi.org/10.1117/12.849796.

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Choma, Michael A., Siavash Yazdanfar, and Joseph A. Izatt. "Wavelet and Eigenfrequency spectral analysis of color Doppler optical coherence tomography." In Biomedical Optics 2003, edited by Valery V. Tuchin, Joseph A. Izatt, and James G. Fujimoto. SPIE, 2003. http://dx.doi.org/10.1117/12.479040.

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Hsin Hsiu, Wei-Chen Hsu, Chia Liang Hsu, Shih-Min Huang, Ming-Yie Jan, Wei-Kung Wang, and Yuh-Ying Lin Wang. "Spectral analysis on the microcirculatory laser Doppler signal at the acupuncture point." In 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2008. http://dx.doi.org/10.1109/iembs.2008.4649348.

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Hsin Hsiu, Wei-Chen Hsu, Chia Liang Hsu, Shih-Min Huang, Tse-Lin Hsu, and Yuh-Ying Lin Wang. "Spectral analysis on the microcirculatory laser Doppler signal of the acupuncture effect." In 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2008. http://dx.doi.org/10.1109/iembs.2008.4649813.

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Pierce, Mark C., Chulmin Joo, Barry Cense, Eli Weinberg, Boris Hyle Park, Mircea Mujat, Jeffrey Borenstein, Guillermo J. Tearney, Brett E. Bouma, and Johannes F. de Boer. "Fluid flow analysis in microfluidic devices by spectral-domain optical Doppler tomography." In Biomedical Optics 2005, edited by Tuan Vo-Dinh, Warren S. Grundfest, David A. Benaron, and Gerald E. Cohn. SPIE, 2005. http://dx.doi.org/10.1117/12.589862.

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Pierce, Mark C., Chulmin Joo, Barry Cense, Eli J. Weinberg, B. Hyle Park, Mircea Mujat, Jeffrey Borenstein, Guillermo J. Tearney, Brett E. Bouma, and Johannes F. de Boer. "Fluid flow analysis in microfluidic devices by spectral-domain optical Doppler tomography." In Biomedical Optics 2005, edited by Valery V. Tuchin, Joseph A. Izatt, and James G. Fujimoto. SPIE, 2005. http://dx.doi.org/10.1117/12.592864.

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Wizemann, H. D., and K. Niemax. "Isotope-Selective Analysis by Diode Laser Spectrometry." In Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/lacea.1998.ltuc.5.

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Single-mode laser diodes of the etalon-type generate radiation of very narrow bandwidth, typically 0.04 nm, in the red and near-infrared wavelength range [1]. The linewidth of such diodes is considerably narrower than the line widths of free atoms in thermal atomizers, analytical flames, or plasmas. Therefore, these laser diodes are proper tools for analytical high-resolution laser spectroscopy. The necessary condition for high-resolution measurements is the atomization of the samples in low-pressure atmospheres (≤ 10 hPa), where pressure broadening of the analyte lines is small and line broadening is dominated by the Doppler effect. If the shifts of spectral lines by the isotope effect are larger than the Doppler-widths of the individual components, the isotope composition of the elements can be measured by Doppler-limited laser spectroscopy. This is often sufficient for light and heavy elements, where large isotope line shifts occur due to the classical Bohr mass shift or due to the volume or field shift, respectively. For medium heavy elements the dominating contribution to isotope shift is the relatively small specific mass shift. This means in general, that for these elements Doppler-free spectroscopic methods are required, such as saturation spectroscopy or Doppler-free two photon excitation [2].

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Звіти організацій з теми "Spectral Doppler analysis"

Mokole, Eric L. Clutter-Doppler Spectral Analysis for a Space-Based Radar. Fort Belvoir, VA: Defense Technical Information Center, May 1991. http://dx.doi.org/10.21236/ada236644.

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Tire Experimental Characterization Using Contactless Measurement Methods. SAE International, August 2021. http://dx.doi.org/10.4271/2021-01-1114.

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In the frame of automotive Noise Vibration and Harshness (NVH) evaluation, inner cabin noise is among the most important indicators. The main noise contributors can be identified in engine, suspensions, tires, powertrain, brake system, etc. With the advent of E-vehicles and the consequent absence of the Internal Combustion Engine (ICE), tire/road noise has gained more importance, particularly at mid-speed driving and in the spectrum up to 300 Hz. At the state of the art, the identification and characterization of Noise and Vibration sources rely on pointwise sensors (microphones, accelerometers, strain gauges). Optical methods such as Digital Image Correlation (DIC) and Laser Doppler Vibrometer (LDV) have recently received special attention in the NVH field because they can be used to obtain full-field measurements. Moreover, these same techniques could also allow to characterize the tire behavior in operating conditions, which would be practically impossible to derive with standard techniques. In this paper we will demonstrate how non-contact full-field measurement techniques can be used to reliably and robustly characterize the tire behavior up to 300 Hz, focusing on static conditions. Experimental modal analysis will extract the modal characteristic of the tire in both free-free and statically preloaded boundary conditions, using both DIC and LDV. The extracted natural frequencies, damping ratios and full-field mode shapes will be used on one side to improve the accuracy of tire models (either by deriving FRF based models or updating FE ones) but also as a reference for future investigation on the tire behavior characterization in rotating conditions.

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