Bibliographies thématiques / Ultrasound Pulse Wave

Littérature scientifique sur le sujet « Ultrasound Pulse Wave »

Auteur : Grafiati
Publié le 10 mars 2023

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Articles de revues sur le sujet "Ultrasound Pulse Wave"

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Nogueira, Rodrigo B., Lucas A. Pereira, Alice F. Basso, Ingrid S. da Fonseca et Lorena A. Alves. « Arterial pulse wave propagation velocity in healthy dogs by pulse wave Doppler ultrasound ». Veterinary Research Communications 41, no 1 (8 décembre 2016) : 33–40. http://dx.doi.org/10.1007/s11259-016-9669-2.

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Szabo, Thomas L. « Langevin’s contributions to pulse echo piezoelectric transducers ». Journal of the Acoustical Society of America 152, no 4 (octobre 2022) : A30. http://dx.doi.org/10.1121/10.0015433.

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Paul Langevin made fundamental discoveries which laid the foundations of modern pulse echo ultrasound over a hundred years ago. He was the first to employ piezoelectric crystals, X-cut quartz, with the propagation and electric axes aligned. In his design, the crystal thickness was a half-wavelength longitudinal wave resonator for both a transmitter and receiver which is the most popular configuration in use today. He invented the Langevin transducer which added two quarter wave layers on either side of the piezoelectric crystal to increase overall efficiency. A mosaic pattern embodied smaller pieces of scarce quartz. His original designs will be demonstrated through simulator models. By selecting ultrasound frequency of 40 KHz, he was able to make more directive beams and extend range for pulse echo detection. By adding triode amplifiers, the sensitivity of reception was increased greatly, and transmission powers of a kilowatt were achieved. With special circuits for making short pulses, long range, high resolution pulse echo ranging became a practical reality. Langevin’s innovations led to sonar and eventually to ultrasound imaging.
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Gurevich, S. Yu, et A. A. Shulginov. « TO THE THEORY OF LASER GENERATION OF ELASTIC WAVES IN FERROMAGNETIC METALS AT THE TEMPERATURE OF MAGNETIC PHASE TRANSITION ». Bulletin of the South Ural State University series "Mathematics. Mechanics. Physics" 13, no 3 (2021) : 69–78. http://dx.doi.org/10.14529/mmph210309.

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Laser generation of ultrasound has found wide application in modern technologies: to control the quality of composite materials, to detect layer separation in adhesive-bonded joints, subsurface and surface defects, as well as the quality of a product's surface in the process of manufacture. For excitation of waves in metals, pulse laser is normally used. In metallurgy, as well as in promising 3D technologies, it is necessary to control products at high temperatures (800°С and higher). To design ultrasound equipment with a pulsed laser radiation generator as the ultrasound source, it is required to conduct theoretical research of the process of laser generation of ultrasound in ferromagnetic metals at the temperature of magnetic phase transition, since the hot metal conversion for ferrum and ferrum-based alloys is, as a rule, performed namely at this temperature of 768 °С. The results of the experimental works allow to conclude that the temperature dependence of normalized amplitude of acoustic pulse in ferrum is of extreme character in the range of magnetic phase transition, i.e., in the range of Curie point. In this work a goal has been set to study the process of laser generation of ultrasound in ferromagnetic metal in the condition of non-linear dependence of the volume-expansion coefficient on the temperature. The task of thermoelastic excitation of longitudinal and transverse waves in ferromagnetic metal by a laser pulse at the temperature of magnetic phase transition has been solved. Diagrams of longitudinal and transverse wave patterns when ferromagnetic metal is exposed to laser pulses of various diameters have been obtained. Recommendations for effective use of laser generation of ultrasound in non-destructive testing and thickness measurement have been given.
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Jiang, Benyu, Baoming Liu, Karen L. McNeill et Philip J. Chowienczyk. « Measurement of Pulse Wave Velocity Using Pulse Wave Doppler Ultrasound : Comparison with Arterial Tonometry ». Ultrasound in Medicine & ; Biology 34, no 3 (mars 2008) : 509–12. http://dx.doi.org/10.1016/j.ultrasmedbio.2007.09.008.

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Shimizu, Kyosuke, Ayumu Osumi et Youichi Ito. « Lamb wave pulse compression in airborne ultrasound excitation ». Acoustical Science and Technology 44, no 2 (1 mars 2023) : 141–44. http://dx.doi.org/10.1250/ast.44.141.

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WESTERMARK, Sara, Hans WIKSELL, Håkan ELMQVIST, Kjell HULTENBY et Hans BERGLUND. « Effect of externally applied focused acoustic energy on clot disruption in vitro ». Clinical Science 97, no 1 (21 mai 1999) : 67–71. http://dx.doi.org/10.1042/cs0970067.

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Application of low-frequency ultrasound for clot disruption has been suggested as a potential therapy to enhance thrombus dissolution, but the optimal mode for delivery of ultrasound with clot-disruptive properties has not yet been extensively explored. Target-specific effects are desirable and may be accomplished by focusing the ultrasound. Adequate focusing, however, requires a short wavelength. The aim of this study was to compare the clot-disruptive effects of different modalities of focused acoustic energy. An in vitro model (10 blood clots for each modality) was used to test the clot-disruptive capacity of (i) shock waves generated in an electrohydraulic lithotriptor; (ii) focused continuous ultrasound of frequency 1.1 MHz, delivered from a specially constructed piezoelectric transducer; and (iii) focused pulse-modulated ultrasound of frequency 1.1 MHz delivered from the same transducer. Exposure to 30 s of focused pulse-modulated ultrasound caused a marked reduction (99±2%) in clot weight compared with 30 shock waves (11±5%) or 30 s exposure to focused continuous wave ultrasound (11±6%) (P< 0.0001). The observed marked and rapid disruptive effect on blood clots of focused high-frequency ultrasound indicates an alternative approach for external ultrasound-mediated thrombus destruction in vivo. The focused pulse-modulated technique has potential to exhibit the desired effect in a well-defined target volume and provides the means for control of the average power.
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Hisaka, Masaki, Tadao Sugiura et Satoshi Kawata. « Optical cross-sectional imaging with pulse ultrasound wave assistance ». Journal of the Optical Society of America A 18, no 7 (1 juillet 2001) : 1531. http://dx.doi.org/10.1364/josaa.18.001531.

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Song, Minho, Oleg A. Sapozhnikov, Yak-Nam Wang, Joo Ha Hwang et Tatiana D. Khokhlova. « Passive and Doppler-based assessment of cavitation activity induced by pulsed focused ultrasound ». Journal of the Acoustical Society of America 152, no 4 (octobre 2022) : A249—A250. http://dx.doi.org/10.1121/10.0016171.

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Pulsed focused ultrasound (pFUS) exposures utilizing short, nonlinearly distorted pulses at low duty cycle have been shown to enhance drug and gene delivery to targeted tissue through inertial cavitation activity. Passive cavitation detection (PCD) and mapping of broadband emissions are current conventional methods to monitor and quantify cavitation but provide limited spatial resolution. Here, plane-wave Doppler imaging was used with PCD to quantify pFUS-induced cavitation in ex vivo bovine tissues and in vivo surgically exposed porcine liver, kidney, and pancreas. A 1.5 MHz FUS transducer (aperture 75 mm, F-number 0.75) was used to deliver 60 pulses (duration 1 ms, 0.1% duty cycle, focal pressure p+ = 70i–110 MPa, p− = 13–20 MPa). A coaxially mounted ATL P7-4 ultrasound imaging probe was used for PCD during the FUS pulse, and Doppler and B-mode sequences. Disrupted tissue areas were collected for histology and compared to Doppler power images. Maximum Doppler power was found to correlate to broadband noise level for each FUS pulse. The Doppler power map integrated over the exposure was observed to correlate spatially with tissue disruption area from histology, which thus represents a promising real-time metric for quantifying cavitation activity induced by pFUS exposures. [Work supported by NIH R01CA154451, R01EB025187, and R01EB23910.]
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Xu, Lirui, Peng Wang, Pan Xia, Pang Wu, Xianxiang Chen, Lidong Du, Jiexin Liu, Ning Xue et Zhen Fang. « A Flexible Ultrasound Array for Local Pulse Wave Velocity Monitoring ». Biosensors 12, no 7 (30 juin 2022) : 479. http://dx.doi.org/10.3390/bios12070479.

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Pulse wave velocity (PWV) measured at a specific artery location is called local PWV, which provides the elastic characteristics of arteries and indicates the degree of arterial stiffness. However, the large and cumbersome ultrasound probes require an appropriate sensor position and pressure maintenance, introducing usability constraints. In this paper, we developed a light (0.5 g) and thin (400 μm) flexible ultrasound array by encapsulating 1–3 composite piezoelectric transducers with a silicone elastomer. It can capture the distension waveforms of four arterial positions with a spacing of 10 mm and calculate the local PWV by multi-point fitting. This is illustrated by in vivo experiments, where the local PWV value of five normal subjects ranged from 3.07 to 4.82 m/s, in agreement with earlier studies. The beat-to-beat coefficient of variation (CV) is 12.0% ± 3.5%, showing high reliability. High reproducibility is shown by the results of two groups of independent measurements of three subjects (the error between the mean values is less than 0.3 m/s). These properties of the developed flexible ultrasound array enable the bandage-like application of local PWV monitoring to skin surfaces.
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Ricci, Stefano, et Valentino Meacci. « Data-Adaptive Coherent Demodulator for High Dynamics Pulse-Wave Ultrasound Applications ». Electronics 7, no 12 (14 décembre 2018) : 434. http://dx.doi.org/10.3390/electronics7120434.

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Pulse-Wave Doppler (PWD) ultrasound has been applied to the detection of blood flow for a long time; recently the same method was also proven effective in the monitoring of industrial fluids and suspensions flowing in pipes. In a PWD investigation, bursts of ultrasounds at 0.5–10 MHz are periodically transmitted in the medium under test. The received signal is amplified, sampled at tens of MHz, and digitally processed in a Field Programmable Gate Array (FPGA). First processing step is a coherent demodulation. Unfortunately, the weak echoes reflected from the fluid particles are received together with the echoes from the high-reflective pipe walls, whose amplitude can be 30–40 dB higher. This represents a challenge for the input dynamics of the system and the demodulator, which should clearly detect the weak fluid signal while not saturating at the pipe wall components. In this paper, a numerical demodulator architecture is presented capable of auto-tuning its internal dynamics to adapt to the feature of the actual input signal. The proposed demodulator is integrated into a system for the detection of the velocity profile of fluids flowing in pipes. Simulations and experiments with the system connected to a flow-rig show that the data-adaptive demodulator produces a noise reduction of at least of 20 dB with respect to different approaches, and recovers a correct velocity profile even when the input data are sampled at 8 bits only instead of the typical 12–16 bits.
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Thèses sur le sujet "Ultrasound Pulse Wave"

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Xu, Minnan 1979. « Local measurement of the pulse wave velocity using Doppler ultrasound ». Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16868.

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Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (p. 77-79).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cardiovascular disease is the leading cause of death in many developed countries. Arteries of people suffering from this disease become stiff and blocked by fatty deposits. In recent years, non-invasive imaging techniques have been playing an increasingly important role in detecting the development of cardiovascular disease. Several methods focus on the measurement of pulse wave velocity, the velocity at which the pressure wave propagates, because it is directly related to arterial stiffness. The objective of this project is to investigate the feasibility of measuring local pulse wave velocity from the blood flow waveforms acquired by Doppler ultrasound. The proposed method includes the following steps: first acquire flow waveforms by Doppler ultrasound at two locations within the same artery, next detect the delay or difference in arrival time of the flow wave at the two arterial locations, and then calculate the PWV by dividing the length of the arterial segment being imaged by the calculated time delay. Although at the conclusion of this study reliable pulse wave velocity detection is not achieved, the study sheds light on many important issues surrounding this potential application. The project explores how sources of variations such as radial positioning of the probe and noise level affect the accuracy of the delay estimate.
by Minnan Xu.
M.Eng.and S.B.
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Abbagoni, Baba Musa. « Experimental investigations of two-phase flow measurement using ultrasonic sensors ». Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/11832.

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This thesis presents the investigations conducted in the use of ultrasonic technology to measure two-phase flow in both horizontal and vertical pipe flows which is important for the petroleum industry. However, there are still key challenges to measure parameters of the multiphase flow accurately. Four methods of ultrasonic technologies were explored. The Hilbert-Huang transform (HHT) was first applied to the ultrasound signals of air-water flow on horizontal flow for measurement of the parameters of the two- phase slug flow. The use of the HHT technique is sensitive enough to detect the hydrodynamics of the slug flow. The results of the experiments are compared with correlations in the literature and are in good agreement. Next, experimental data of air-water two-phase flow under slug, elongated bubble, stratified-wavy and stratified flow regimes were used to develop an objective flow regime classification of two-phase flow using the ultrasonic Doppler sensor and artificial neural network (ANN). The classifications using the power spectral density (PSD) and discrete wavelet transform (DWT) features have accuracies of 87% and 95.6% respectively. This is considerably more promising as it uses non-invasive and non-radioactive sensors. Moreover, ultrasonic pulse wave transducers with centre frequencies of 1MHz and 7.5MHz were used to measure two-phase flow both in horizontal and vertical flow pipes. The liquid level measurement was compared with the conductivity probes technique and agreed qualitatively. However, in the vertical with a gas volume fraction (GVF) higher than 20%, the ultrasound signals were attenuated. Furthermore, gas-liquid and oil-water two-phase flow rates in a vertical upward flow were measured using a combination of an ultrasound Doppler sensor and gamma densitometer. The results showed that the flow gas and liquid flow rates measured are within ±10% for low void fraction tests, water-cut measurements are within ±10%, densities within ±5%, and void fractions within ±10%. These findings are good results for a relatively fast flowing multiphase flow.
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Widman, Erik. « Ultrasonic Methods for Quantitative Carotid Plaque Characterization ». Doctoral thesis, KTH, Medicinsk bildteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192339.

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Cardiovascular diseases are the leading causes of death worldwide and improved diagnostic methods are needed for early intervention and to select the most suitable treatment for patients. Currently, carotid artery plaque vulnerability is typically determined by visually assessing ultrasound B-mode images, which is influenced by user-subjectivity. Since plaque vulnerability is correlated to the mechanical properties of the plaque, quantitative techniques are needed to estimate plaque stiffness as a surrogate for plaque vulnerability, which would reduce subjectivity during plaque assessment. The work in this thesis focused on three noninvasive ultrasound-based techniques to quantitatively assess plaque vulnerability and measure arterial stiffness. In Study I, a speckle tracking algorithm was validated in vitro to assess strain in common carotid artery (CCA) phantom plaques and thereafter applied in vivo to carotid atherosclerotic plaques where the strain results were compared to visual assessments by experienced physicians. In Study II, hard and soft CCA phantom plaques were characterized with shear wave elastography (SWE) by using phase and group velocity analysis while being hydrostatically pressurized followed by validating the results with mechanical tensile testing. In Study III, feasibility of assessing the stiffness of simulated plaques and the arterial wall with SWE was demonstrated in an ex vivo setup in small porcine aortas used as a human CCA model. In Study IV, SWE and pulse wave imaging (PWI) were compared when characterizing homogeneous CCA soft phantom plaques. The techniques developed in this thesis have demonstrated potential to characterize carotid artery plaques. The results show that the techniques have the ability to noninvasively evaluate the mechanical properties of carotid artery plaques, provide additional data when visually assessing B-mode images, and potentially provide improved diagnoses for patients suffering from cerebrovascular diseases.

Doctoral thesis in medical technology and medical sciences

QC 20160921

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Goudot, Guillaume. « Applications innovantes des ultrasons en pathologie vasculaire : utilisation de l'imagerie ultrarapide dans l'analyse de la rigidité artérielle et des ultrasons pulsés en thérapie Arterial stiffening assessed by ultrafast ultrasound imaging gives new insight into arterial phenotype of vascular Ehlers–Danlos mouse models Aortic wall elastic properties in case of bicuspid aortic valve Segmental aortic stiffness in bicuspid aortic valve patients compared to first-degree relatives Wall shear stress measurement by ultrafast vector flow imaging for atherosclerotic carotid stenosis Pulsed cavitational therapy using high-frequency ultrasound for the treatment of deep vein thrombosis in an in vitro model of human blood clot ». Thesis, Sorbonne Paris Cité, 2018. https://wo.app.u-paris.fr/cgi-bin/WebObjects/TheseWeb.woa/wa/show?t=2215&f=13951.

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Mezuláníková, Radka. « Vyhodnocení rychlosti šíření tlakové vlny v lidském těle ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220037.

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This Mater's thesis deals with the evaluation of pulse wave velocity using multi-channel whole-body impedance cardiography. Data were taken from the group of healthy volunteers whose impedance changes were measured during rest, respiratory maneuvers, tilt and stress exercise. The result of this measurement are values of peaks of pulse wave time shifts towards R-wave. The velocity values towards the thorax electrodes were recalculated on the basis of knowledge about the pulse wave time shifts and the distances from the heart to the scanned locations, which were measured using the arterial segment's lengths.
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Ghasemi, Negareh. « Improving ultrasound excitation systems using a flexible power supply with adjustable voltage and frequency to drive piezoelectric transducers ». Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/61091/1/Negareh_Ghasemi_Thesis.pdf.

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The ability of a piezoelectric transducer in energy conversion is rapidly expanding in several applications. Some of the industrial applications for which a high power ultrasound transducer can be used are surface cleaning, water treatment, plastic welding and food sterilization. Also, a high power ultrasound transducer plays a great role in biomedical applications such as diagnostic and therapeutic applications. An ultrasound transducer is usually applied to convert electrical energy to mechanical energy and vice versa. In some high power ultrasound system, ultrasound transducers are applied as a transmitter, as a receiver or both. As a transmitter, it converts electrical energy to mechanical energy while a receiver converts mechanical energy to electrical energy as a sensor for control system. Once a piezoelectric transducer is excited by electrical signal, piezoelectric material starts to vibrate and generates ultrasound waves. A portion of the ultrasound waves which passes through the medium will be sensed by the receiver and converted to electrical energy. To drive an ultrasound transducer, an excitation signal should be properly designed otherwise undesired signal (low quality) can deteriorate the performance of the transducer (energy conversion) and increase power consumption in the system. For instance, some portion of generated power may be delivered in unwanted frequency which is not acceptable for some applications especially for biomedical applications. To achieve better performance of the transducer, along with the quality of the excitation signal, the characteristics of the high power ultrasound transducer should be taken into consideration as well. In this regard, several simulation and experimental tests are carried out in this research to model high power ultrasound transducers and systems. During these experiments, high power ultrasound transducers are excited by several excitation signals with different amplitudes and frequencies, using a network analyser, a signal generator, a high power amplifier and a multilevel converter. Also, to analyse the behaviour of the ultrasound system, the voltage ratio of the system is measured in different tests. The voltage across transmitter is measured as an input voltage then divided by the output voltage which is measured across receiver. The results of the transducer characteristics and the ultrasound system behaviour are discussed in chapter 4 and 5 of this thesis. Each piezoelectric transducer has several resonance frequencies in which its impedance has lower magnitude as compared to non-resonance frequencies. Among these resonance frequencies, just at one of those frequencies, the magnitude of the impedance is minimum. This resonance frequency is known as the main resonance frequency of the transducer. To attain higher efficiency and deliver more power to the ultrasound system, the transducer is usually excited at the main resonance frequency. Therefore, it is important to find out this frequency and other resonance frequencies. Hereof, a frequency detection method is proposed in this research which is discussed in chapter 2. An extended electrical model of the ultrasound transducer with multiple resonance frequencies consists of several RLC legs in parallel with a capacitor. Each RLC leg represents one of the resonance frequencies of the ultrasound transducer. At resonance frequency the inductor reactance and capacitor reactance cancel out each other and the resistor of this leg represents power conversion of the system at that frequency. This concept is shown in simulation and test results presented in chapter 4. To excite a high power ultrasound transducer, a high power signal is required. Multilevel converters are usually applied to generate a high power signal but the drawback of this signal is low quality in comparison with a sinusoidal signal. In some applications like ultrasound, it is extensively important to generate a high quality signal. Several control and modulation techniques are introduced in different papers to control the output voltage of the multilevel converters. One of those techniques is harmonic elimination technique. In this technique, switching angles are chosen in such way to reduce harmonic contents in the output side. It is undeniable that increasing the number of the switching angles results in more harmonic reduction. But to have more switching angles, more output voltage levels are required which increase the number of components and cost of the converter. To improve the quality of the output voltage signal with no more components, a new harmonic elimination technique is proposed in this research. Based on this new technique, more variables (DC voltage levels and switching angles) are chosen to eliminate more low order harmonics compared to conventional harmonic elimination techniques. In conventional harmonic elimination method, DC voltage levels are same and only switching angles are calculated to eliminate harmonics. Therefore, the number of eliminated harmonic is limited by the number of switching cycles. In the proposed modulation technique, the switching angles and the DC voltage levels are calculated off-line to eliminate more harmonics. Therefore, the DC voltage levels are not equal and should be regulated. To achieve this aim, a DC/DC converter is applied to adjust the DC link voltages with several capacitors. The effect of the new harmonic elimination technique on the output quality of several single phase multilevel converters is explained in chapter 3 and 6 of this thesis. According to the electrical model of high power ultrasound transducer, this device can be modelled as parallel combinations of RLC legs with a main capacitor. The impedance diagram of the transducer in frequency domain shows it has capacitive characteristics in almost all frequencies. Therefore, using a voltage source converter to drive a high power ultrasound transducer can create significant leakage current through the transducer. It happens due to significant voltage stress (dv/dt) across the transducer. To remedy this problem, LC filters are applied in some applications. For some applications such as ultrasound, using a LC filter can deteriorate the performance of the transducer by changing its characteristics and displacing the resonance frequency of the transducer. For such a case a current source converter could be a suitable choice to overcome this problem. In this regard, a current source converter is implemented and applied to excite the high power ultrasound transducer. To control the output current and voltage, a hysteresis control and unipolar modulation are used respectively. The results of this test are explained in chapter 7.
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Carbol, Ladislav. « Měření akustických vlastností stavebních materiálů pomocí pseudonáhodné sekvence ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-355599.

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The thesis deals with research of pulse compression of the acoustic signal in terms of applications in civil engineering. Based on the study and analysis of these methods, automated measuring equipment for non-destructive testing with pseudorandom sequence of maximum length and automated signal analysis, have been designed and implemented. In a single test cycle are obtained three parameters that characterize the linear and nonlinear behavior of the sample. A nonlinear parameter, Time of Flight of ultrasonic wave in the sample is further in the work compared with the conventional pulse measuring, and spectral analysis is compared with the method impact-echo. Functionality and optimization of the testing method was performed on a total of three sets of test pieces made of various building materials. The experiments proved simple result interpretation, and high sensitivity to structural damage associated with temperature loading. The results were correlated with conventional nondestructive methods and by destructive testing was measured change in compressive strength and flexural strength. This work also includes continual measurement of fundamental frequency influenced by moisture on a mortar sample. Use of pulse compression signal is in the civil engineering quite unusual. Only in recent years this topic is discussed in scientific articles with increasing frequency. Great potential lies in the association of three test methods into a single. Beneficial is high test speed and measurement reproducibility, but also theoretical possibility of testing massive test elements.
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Salles, Sébastien. « Estimation du mouvement de la paroi carotidienne en imagerie ultrasonore par une approche de marquage ultrasonore ». Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0092/document.

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Ce travail de thèse est axé sur le domaine du traitement d’images biomédicales. L’objectif de notre étude est l’estimation des paramètres traduisant les propriétés mécaniques de l’artère carotide in vivo en imagerie échographique, dans une optique de détection précoce des pathologies cardiovasculaires. L’étude des comportements dynamiques de l’artère pour le dépistage précoce de l’athérosclérose constitue à ce jour une piste privilégiée. Cependant, malgré les avancées récentes, l’estimation du mouvement de la paroi carotidienne reste toujours difficile, notamment dans la direction longitudinale (direction parallèle au vaisseau). L’élaboration d’une méthode innovante permettant d’étudier le mouvement de la paroi carotidienne constitue la principale motivation de ce travail de thèse. Les trois contributions principales proposées dans ce travail sont i) le développement, la validation, et l’évaluation clinique d’une méthode originale d’estimation de mouvement 2D adaptée au mouvement de la paroi carotidienne, ii) la validation en simulation, et expérimentale de l’extension à la 3D de la méthode d’estimation proposée, et iii) l’évaluation expérimentale de la méthode proposée, en imagerie ultrasonore ultra-rapide, dans le cadre de l’estimation locale de la vitesse de l’onde de pouls. Nous proposons une méthode d’estimation de mouvement combinant un marquage ultrasonore dans la direction latérale, et un estimateur de mouvement basé sur la phase des images ultrasonores. Le marquage ultrasonore est réalisé par l’intermédiaire d’oscillations transverses. Nous proposons deux approches différentes pour introduire ces oscillations transverses, une approche classique utilisant une fonction de pondération spécifique, et une approche originale par filtrage permettant de contrôler de manière optimale leurs formations. L’estimateur de mouvement proposé utilise les phases analytiques des images radiofréquences, extraites par l’approche de Hahn. Ce travail de thèse montre que la méthode proposée permet une estimation de mouvement plus précise dans la direction longitudinale, et plus généralement dans les directions perpendiculaires au faisceau ultrasonore, que celle obtenue avec d’autres méthodes plus traditionnelles. De plus, l’évaluation expérimentale de la méthode sur des séquences d’images ultrasonores ultra-rapides issues de fantômes de carotide, a permis l’estimation locale de la vitesse de propagation de l’onde de pouls, la mise en évidence de la propagation d’un mouvement longitudinal et enfin l’estimation du module de Young des vaisseaux
This work focuses on the processing of biomedical images. The aim of our study is to estimate the mechanical properties of the carotid artery in vivo using ultrasound imaging, in order to detect cardiovascular diseases at an early stage. Over the last decade, researchers have shown interest in studying artery wall motion, especially the motion of the carotid intima-media complex in order to demonstrate its significance as a marker of Atherosclerosis. However, despite recent progress, motion estimation of the carotid wall is still difficult, particularly in the longitudinal direction (direction parallel to the probe). The development of an innovative method for studying the movement of the carotid artery wall is the main motivation of this thesis. The three main contributions proposed in this work are i) the development, the validation, and the clinical evaluation of a novel method for 2D motion estimation of the carotid wall, ii) the development, the simulation and the experimental validation of the 3D extension of the estimation method proposed, and iii) the experimental evaluation of the 2D proposed method in ultra-fast imaging, for the estimation of the local pulse wave velocity. We propose a motion estimation method combining tagging of the ultrasound images, and a motion estimator based on the phase of the ultrasound images. The ultrasonic tagging is produced by means of transverse oscillations. We present two different approaches to introduce these transverses oscillations, a classic approach using a specific apodization function and a new approach based on filtering. The proposed motion estimator uses the 2D analytical phase of RF images using the Hahn approach. This thesis work shows that, compared with conventional methods, the proposed approach provides more accurate motion estimation in the longitudinal direction, and more generally in directions perpendicular to the beam axis. Also, the experimental evaluation of our method on ultra-fast images sequences from carotid phantom was used to validate our method regarding the estimation of the pulse wave velocity, the Young’s modulus of the vessels wall, and the propagation of a longitudinal movement
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Векерик, В. В. « Акустичний контроль геометричних параметрів обсадних колон в свердловині ». Thesis, Івано-Франківський національний технічний університет нафти і газу, 2004. http://elar.nung.edu.ua/handle/123456789/4014.

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Показано і обгрунтовано, що найбільш інформативним з параметрів, які відповідають за працездатність обсадних колон і визначають їх фактичний технічний стан, є геометричні параметри. На основі проведених теоретичних та експериментальних досліджень розроблено способи акустичного контролю геометричних параметрів трубних виробів зсередини та методологію застосування з цією метою акустичного луна-імпульсного методу контролю в експлуатаційних умовах свердловини. Експериментально досліджено залежність швидкості поширення поздовжньої ультразвукової хвилі в матеріалі обсадних труб та чутливості акустичного тракту від експлуатаційних факторів свердловини. Розроблено математичну модель контролю (роботи акустичного тракту та розрахунку акустичного поля) в умовах свердловини. Розроблено комплекс технічних засобів для акустичного контролю геометричних параметрів обсадних колон в свердловині.
Работоспособность обсадных колонн - один из главных факторов, влияющих на производительность и безопасность работы скважины. Отказы элементов обсадных колонн проявляются как при спуске и креплении колонны, так и во время освоения скважины и, особенно, в процессе ее продолжительной (более 20 лет) эксплуатации. Бывают случаи, когда через аварии с обсадными колоннами ликвидируют скважины, не выполнившие своего целевого назначения. Особенно актуальны вопросы контроля обсадных колонн подземных хранилищ газа, глубоких скважин и скважин, которые продолжительное время были на консервации. Практическое значение полученных результатов состоит в том, что разработанные способы и средства контроля позволяют: обеспечить контроль технического состояния обсадных колонн непосредственно в скважине; повысить надежность работы глубинного устройства благодаря использованию невращающейся системы сканирования и уменьшить её габаритные размеры благодаря использованию только одного измерительного канала и одного преобразователя, что играет значительную роль при конструировании средств внутритрубного контроля.
Is shown and prove that most informative parameters, which responsible for operational reliability of casing strings and which determine their actual technical condition, are the geometrical parameters. According to theoretical and experimental researches the means of the acoustic testing of geometrical parameters of pipes from their internal side and methodology of application with this purpose an acoustic pulse-echo method of the testing in operational conditions of a well was developed. Dependence of a speed of longitudinal ultrasonic wave propagation in a material of casing string and sensitivity of an acoustic tract from the operational factors experimentally are investigated. The mathematical model of the testing (of a work of an acoustic tract and estimation of an acoustic field) in conditions of a well is developed. The complex of means of the acoustic testing of geometrical parameters of casing strings in a well is developed.
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Resende, Rafaella Moreira Lima Gondim. « Avaliação dos efeitos da danificação e da acustoelasticidade sobre a velocidade de pulso ultrassônico em corpos de prova de concreto submetidos a compressão uniaxial ». Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-21052018-121753/.

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A teoria da acustoelasticidade relaciona a variação de velocidade de propagação de ondas mecânicas à variação de tensão em um meio sólido. Em materiais frágeis como concreto, a danificação altera a velocidade de propagação paralelamente ao efeito acustoelástico. O objetivo deste trabalho é identificar e quantificar como a danificação e o efeito acustoelástico agem sobre a Velocidade de Pulso Ultrassônico (VPU) em corpos de prova de concreto submetidos a compressão uniaxial. Para tanto, foram realizadas três fases de ensaio. A primeira fase objetivou gerar dados para a análise da aplicação da interferometria de cauda de onda (Coda Wave Interferometry – CWI). Duas variações deste método foram estudadas e comparadas, com o propósito de determinar-se qual gera melhores resultados e quais parâmetros devem ser adotados para as análises. Para tal, um código computacional foi desenvolvido utilizando a linguagem Python 3.6.0. Foi constatado que a técnica do alongamento apresenta resultados melhores que a técnica tradicional da interferometria de cauda de onda. A segunda etapa foi dedicada ao estudo da variação de velocidade de propagação devido à recuperação de dano do corpo de prova. A terceira fase abordou a influência da geometria da amostra e da composição do concreto sobre a resposta do material à acustoelasticidade. Além disso, definiu-se um Índice de Dano (D) baseado na redução do módulo de elasticidade devido ao carregamento, a fim de isolar a variação de velocidade causada pelo efeito acustoelástico. Quanto ao estudo da recuperação de dano ao longo do tempo, a variação relativa de velocidade nas primeiras 24 horas após a retirada do carregamento se mostrou muito pequena em relação às variações geradas pelas condições de temperatura e umidade. Concluiu-se também que as amostras cilíndricas apresentaram respostas mais uniformes ao efeito acustoelástico que as amostras prismáticas. Por fim, o Índice de Dano se mostrou eficaz para isolar os efeitos da danificação e da acustoelasticidade sobre a VPU.
The acoustoelasticity theory relates the variation in propagation velocity of mechanical waves to the stress variation in a solid medium. In brittle materials such as concrete, damage affects the propagation velocity parallel to the acoustoelastic effect. This research aims to identify and quantify how damage and acoustoelastic effect act on Ultrasonic Pulse Velocity (UPV) in concrete samples subjected to uniaxial compression. In order to do so, three phases of testing were performed. The first one focused on generating data to analyze the application of the Coda Wave Interferometry (CWI). Two variations of this method were studied and compared, to the purpose of determining which variation shows better results and which parameters should be adopted in the analysis. To enable the analysis, a computational code using Python 3.6.0 language was developed. It was verified that the stretching technique shows better results than the traditional coda wave interferometry technique. The second phase was dedicated to study the variation in propagation velocity due to damage recovery in the sample. The third phase addressed the influence of the sample geometry and the concrete composition over the response from the material to the acoustoelasticity. Furthermore, a Damage Index (D) was defined based on the elastic modulus reduction due to loading, in order to isolate the variation of velocity due solely to the acoustoelastic effect. Regarding the study of damage recovery over time, the relative velocity variation in the first 24 hours following the withdrawal of the loading showed to be too little when compared to the variations caused by temperature and humidity conditions. It was also concluded that the cylindrical samples showed more uniform responses to the acoustoelastic effect than the prismatic samples. Finally, the Damage Index proved itself to be a reliable tool to isolate the effects of damage and acoustoelasticity over the UPV.
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Livres sur le sujet "Ultrasound Pulse Wave"

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Steinman, Aaron H. Errors in phased array pulse-wave ultrasound velocity estimation systems. 2004.

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Nixdorff, Uwe, Stephan Achenbach, Frank Bengel, Pompillio Faggiano, Sara Fernández, Christian Heiss, Thomas Mengden et al. Imaging in cardiovascular prevention. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199656653.003.0006.

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Imaging tools in preventive cardiology can be divided into imaging modalities to assess pre-clinical and clinical atherosclerosis and functional assessments of vascular function or vascular inflammation. To calculate the likelihood of pre-clinical atherosclerosis intima-media thickness as well as coronary calcium scoring are most frequently used. However, beyond these two there are other parameters derived by ultrasound and multi-detector computed tomography as well as magnetic resonance imaging and nuclear/molecular imaging which are discussed in the chapter. Functional tests include flow-mediated dilatation, pulse wave analysis, and the ankle-brachial index. In clinical research other invasive measurements such as intravascular ultrasound/virtual histology/elastography, optical coherence tomography as well as thermography are being used. However, their value in clinical prevention still needs to be established.
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Yu, Alfred C. H. Investigation of transit time broadening in pulsed-wave Doppler ultrasound. 2004.

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Lancellotti, Patrizio, et Bernard Cosyns. Examination. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198713623.003.0001.

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Echocardiography is a diagnostic imaging technique by which ultrasound is used to display anatomic and physiologic characteristics of the cardiovascular system. Echocardiography consists of several different imaging modalities that require appropriate settings. In this chapter the most important system settings are discussed in the context of the basic physics of ultrasound image formation. Setting-up the echo machine to optimize patient examination is discussed in detail. All controls are covered. Continuous-wave, pulsed-wave, and colour flow Doppler are explained, as well as more advanced techniques including myocardial velocity imaging and speckle tracking and 3D imaging. Understanding these basic principles will allow optimizing image quality for each individual patient.
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Galderisi, Maurizio, et Sergio Mondillo. Assessment of diastolic function. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199599639.003.0009.

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Modern assessment of left ventricular (LV) diastolic function should be based on the estimation of degree of LV filling pressure (LVFP), which is the true determinant of symptoms/signs and prognosis in heart failure.In order to achieve this goal, standard Doppler assessment of mitral inflow pattern (E/A ratio, deceleration time, isovolumic relaxation time) should be combined with additional manoeuvres and/or ultrasound tools such as: ◆ Valsalva manoeuvre applied to mitral inflow pattern. ◆ Pulmonary venous flow pattern. ◆ Velocity flow propagation by colour M-mode. ◆ Pulsed wave tissue Doppler of mitral annuls (average of septal and lateral E′ velocity).In intermediate doubtful situations, the two-dimensional determination of left atrial (LA) volume can be diagnostic, since LA enlargement is associated with a chronic increase of LVFP in the absence of mitral valve disease and atrial fibrillation.Some new echocardiographic technologies, such as the speckle tracking-derived LV longitudinal strain and LV torsion, LA strain, and even the three-dimensional determination of LA volumes can be potentially useful to add further information. In particular, the reduction of LV longitudinal strain in patients with LV diastolic dysfunction and normal ejection fraction demonstrates that a subclinical impairment of LV systolic function already exists under these circumstances.
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Chapitres de livres sur le sujet "Ultrasound Pulse Wave"

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Wang, Xuemin, Wei Wang, Xiaozuo Lu et Peng Zhou. « Pulse Wave Detection for Ultrasound Imaging ». Dans Recent Advances in Computer Science and Information Engineering, 633–38. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-25789-6_84.

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Schiffner, Martin F., et Georg Schmitz. « Plane Wave Pulse-Echo Ultrasound Diffraction Tomography with a Fixed Linear Transducer Array ». Dans Acoustical Imaging, 19–30. Dordrecht : Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-2619-2_3.

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Jensen, Jørgen Arendt. « An Analysis of Pulsed Wave Ultrasound Systems for Blood Velocity Estimation ». Dans Acoustical Imaging, 377–84. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4419-8772-3_61.

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Isabel, Arnaiz. « A low cost pulsed wave Doppler ultrasound system on Field Programmable Gate Arrays for vascular studies. » Dans IFMBE Proceedings, 1269–72. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19387-8_308.

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Luria, O., Y. Megel, D. Smakhtin, D. M. Schwake et O. Barnea. « Method for monitoring fetal heart rate from pulsed wave ultrasound during the active stage of labor ». Dans IFMBE Proceedings, 69–72. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03882-2_18.

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Reddi, Ben, et Nick Fletcher. « Physics of ultrasound ». Dans Focused Intensive Care Ultrasound, sous la direction de Marcus Peck et Peter Macnaughton, 9–16. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780198749080.003.0002.

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This chapter will describe the ultrasound wave, how it is produced, and what effect body tissues have on it as it passes through the body. It will describe the key principles that underpin image resolution and discuss the importance of the ultrasound pulse. The advanced section will introduce how Doppler ultrasound and aliasing are produced.
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Erbel, Raimund. « Aortic sclerosis : therapy ». Dans ESC CardioMed, sous la direction de Raimund Erbel, 2583–89. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0613.

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Aortic sclerosis is a very common disease and is related to the atherosclerotic process which can start in young adulthood. The loss of compliance of the aortic ‘Windkessel’ is a major drawback of the disease, leading to enhanced blood pressure amplitude—elevated pulse pressure—due to a higher systolic and a lower diastolic blood pressure. The pressure pulse wave augmentation index and the pulse wave velocity increase. Ultrasound is able to visualize only limited aortic segments, whereas computed tomography and magnetic resonance imaging are the best tools to detect and quantify aortic atheromas. Nevertheless, transoesophageal echocardiography can image the descending thoracic aorta down to the coeliac trunk. An aortic atheroma, particularly one greater than 4 mm in size in the aortic arch, indicates an increased risk of stroke and other cardiovascular events. A grading is helpful. Plaque rupture is quite frequent and often found in multiple segments of the aorta indicating an increased risk of cholesterol emboli due to the wash-out of debris with or without thrombotic material. Free-floating structures, possible remnants of fibrous cap, are found as well as mobile thrombi. Calcification of the thoracic aorta is often found when coronary artery calcification is present, but may be present when coronary artery calcification is absent. Risk prediction of events is, however, not improved. Therapy for aortic sclerosis is based on common and recent guidelines for prevention and treatment of risk factors. Endovascular or surgical interventions are limited to rare situation in which blood flow is not preserved.
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« Ultrasound ». Dans Echocardiography, sous la direction de Paul Leeson, Christiana Monteiro, Daniel Augustine, Harald Becher, Paul Leeson, Christiana Monteiro, Daniel Augustine et Harald Becher, 3–70. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198804161.003.0001.

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After a brief introduction to echocardiography, sound waves, and ultrasound, this chapter covers the following topics: the behaviour of ultrasound in tissue; reflection, attenuation, and depth compensation; reverberation artefacts; transthoracic, transoesophageal, and other transducers; echocardiography modes; transmit power; gain; grey scale and compression; image resolution; fundamental and second harmonic imaging; Doppler echocardiography; spectral trace analysis; continuous wave and pulsed wave Doppler; colour flow mapping; tissue Doppler imaging; second harmonic Doppler for contrast imaging; power Doppler (amplitude) imaging; 3D echocardiography, artefacts, image display, and image rendering; speckle tracking echocardiography; basic fluid dynamics; and the bioeffects of ultrasound.
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Corredor, Carlos, et Nick Fletcher. « Image optimization ». Dans Focused Intensive Care Ultrasound, sous la direction de Marcus Peck et Peter Macnaughton, 17–24. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780198749080.003.0003.

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This chapter will describe how you can optimize the environment, probe selection, depth, gain, compression, focus, sector width, and zoom to obtain the best images possible. The advanced section will introduce practical aspects of colour, pulsed wave, continuous wave, and tissue Doppler imaging and present some of their many limitations, which explain why considerable supervision is required to develop skills in these modalities.
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Simone, Giovanni de, et Antonio Coca. « Target organ damage, cardiovascular disease risk, and clinical evaluation of the hypertensive patient ». Dans ESC CardioMed, sous la direction de Bryan Williams, 2401–9. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0565.

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In addition to a thoughtful clinical evaluation and accurate assessment of blood pressure values, an electrocardiogram must be part of the primary screening in all patients with arterial hypertension to identify left ventricular hypertrophy, using more than one single criterion to increase sensitivity. Standard transthoracic echocardiograms should be performed at least once in all hypertensive patients, to assess left ventricular geometry and type of haemodynamic load, to provide information potentially influencing decision-making, which is especially needed in the absence of other signs of target organ damage. Ultrasound scanning of carotid arteries is useful to detect asymptomatic atherosclerosis, particularly in the elderly. Carotid plaque is identified by intima–media thickness (IMT) of 1.5 mm or greater, or by a focal thickness increase of 0.5 mm or 50% of the surrounding carotid IMT value. Increased aortic stiffness can be estimated in young and middle-aged hypertensive patients by measurement of pulse wave velocity greater than 10 m/s. Other method to refine assessment of target organ damage are less useful in clinical practice, such as the coronary calcium score, wall-to-lumen ratio of small arteries measured in subcutaneous tissues, endothelial dysfunction, echo-tracking for IMT, and three-dimensional reconstruction of carotid plaque volume. Identification of reduced glomerular filtration rate (by the Chronic Kidney Disease Epidemiology Collaboration method) and increase of the spot urinary albumin/creatinine ratio are good markers of renal damage. Cerebral magnetic resonance imaging can identify white matter hyperintensities and silent infarcts, which are associated with an increased risk of stroke, cognitive decline, and dementia.
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Actes de conférences sur le sujet "Ultrasound Pulse Wave"

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Leeman, Sidney, Nicholas Thomas et Andrew J. Healey. « Analysis of ultrasound pulse-wave Doppler systems ». Dans Medical Imaging 1996, sous la direction de Richard L. Van Metter et Jacob Beutel. SPIE, 1996. http://dx.doi.org/10.1117/12.237793.

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Zhang, Xiaoming, et James F. Greenleaf. « Measurement of the Propagation Velocity of Pulse Wave Generated by Ultrasound in Arteries ». Dans ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79619.

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Arterial wall stiffness can be associated with various diseases. The stiffness of an artery can be assessed by measurement of the pulse wave velocity (PWV). Usually, PWV is estimated using the foot-to-foot method. However, the foot of the pressure wave is not very clear due to reflected waves. Also, the blood pressure wave generated by the heart is normally a low frequency wave, hence the time resolution is low. PWV is an average indicator of artery stiffness between two measuring locations, therefore, it is not easy to identify local stiffness. In this paper a short external pulse is generated in an artery by the radiation force of ultrasound. The propagation velocity of the pulse wave is measured along the artery. The temporal resolution of this method, which is in the range of microseconds, is much higher than the conventional pressure PWV method, and therefore allows the wave velocity to be measured accurately over a few millimeters.
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Zhang, Xiaoming, Cristina Pislaru, Randall R. Kinnick et James F. Greenleaf. « Measurement of Arterial Wave Velocity With Ultrasound ». Dans ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43370.

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Pulse wave velocity (PWV) is widely used for estimating the stiffness of an artery. PWV is measured by the time of travel of the “foot” of the pressure wave over a known distance. This technique has a low time resolution and is an average measurement of artery stiffness between the two measuring positions. In this paper an arterial wave is generated non-invasively in the vessel wall by the radiation force of ultrasound. The wave velocity in the vessel is measured non-invasively by ultrasound with high time resolution over a short distance of a few millimeters.
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Singh, Kumar Abhinav, et Ashish Kumar Sahani. « Measurement of Local Pulse Wave Velocity using Fast Ultrasound Imaging ». Dans 2020 IEEE International Symposium on Medical Measurements and Applications (MeMeA). IEEE, 2020. http://dx.doi.org/10.1109/memea49120.2020.9137345.

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Vappou, Jonathan, Jianwen Luo, Kazue Okajima, Marco di Tullio et Elisa Konofagou. « Pulse Wave Ultrasound Manometry (PWUM) : Measuring central blood pressure non-invasively ». Dans 2011 IEEE International Ultrasonics Symposium (IUS). IEEE, 2011. http://dx.doi.org/10.1109/ultsym.2011.0526.

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Kiran V., Raj, Nabeel P.M., Jayaraj Joseph, Malay Ilesh Shah et Mohanasankar Sivaprakasam. « Evaluation of Local Pulse Wave Velocity using an Image Free Ultrasound Technique ». Dans 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA). IEEE, 2018. http://dx.doi.org/10.1109/memea.2018.8438649.

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Faita, Francesco, Nicole Di Lascio, Francesco Stea, Claudia Kusmic et Rosa Sicari. « Assessment of aortic pulse wave velocity by ultrasound : a feasibility study in mice ». Dans SPIE Medical Imaging, sous la direction de Johan G. Bosch et Marvin M. Doyley. SPIE, 2014. http://dx.doi.org/10.1117/12.2042160.

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Ulul A., A. Zahi, Suprijanto et A. Rodik Wijaya. « Prototype of Programmable High Voltage Pulse Generator for Simulator NDT based on Ultrasound Wave ». Dans 2019 6th International Conference on Instrumentation, Control, and Automation (ICA). IEEE, 2019. http://dx.doi.org/10.1109/ica.2019.8916699.

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V, Raj Kiran, Rahul Manoj, Ishwarya S, Nabeel P et Jayaraj Joseph. « Operator Variabilities in Carotid Pulse Wave Velocity Measured by an Image-free Ultrasound Device ». Dans 2022 44th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC). IEEE, 2022. http://dx.doi.org/10.1109/embc48229.2022.9871607.

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Maev, R. Gr, S. Titov et V. Leshchynsky. « Passive and Pulse–Echo Ultrasonic Monitoring of Cold Spray Process ». Dans ITSC 2012, sous la direction de R. S. Lima, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, A. McDonald et F. L. Toma. ASM International, 2012. http://dx.doi.org/10.31399/asm.cp.itsc2012p0357.

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Abstract To fully understand particle interactions with both substrate and neighboring particles in cold spray, ultrasound wave generation and ultrasonic monitoring of particle impacts were studied. The multi–channel ultrasonic system works in pulse– echo and passive modes. In pauses between pulse–echo data acquisition frames the system is in the passive mode receiving the signals generated by the particle impacts. The particles being deposited generate the ultrasonic signals in a very wideband frequency range at more than 40 dB signal-to-noise ratio. The particle impact signals are considered as a sum of the background wideband noise and the sparse strong pulses observed when the nozzle passes over the location of the transducer. It was shown that these components of the particle impact signal can be separated by threshold processing. The results of the passive monitoring are confirmed by the ultrasonic pulse–echo and direct measurements of a deposited coating geometry.
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