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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 73 for “"acoustic radiation"”.
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Acoustic Radiation Force Impulse Imaging of Myocardial Performance
… myocardial performance is myocardial stiffness. Acoustic radiation force impulse (ARFI) imaging has been demonstrated to be capable of visualizing variations in local stiffness within soft tissue. </p><p>In this thesis, the initial investigations into the visualization of myocardial performance …
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Active control of broadband acoustic radiation from structures
Active Structural Acoustic Control (ASAC) has been previously demonstrated for systems excited by single and multiple frequency disturbances. This work is an extension of ASAC techniques to the control of sound radiation from structures excited by a disturbance with broadband frequency content. An …
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Volumetric Acoustic Radiation Force Impulse Imaging Using Intracardiac Echocardiography
… helicoid array transducers to perform ICE-based acoustic radiation force impulse (ARFI) imaging on multiple elevation planes at once, improving on current methods in terms of speed and ease-of-use.</p><p>The Siemens Acuson SC2000 ultrasound scanner was programmed with sequences to perform SWEI …
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Identifying Vulnerable Plaques with Acoustic Radiation Force Impulse Imaging
… dissertation evaluates the hypothesis that Acoustic Radiation Force Impulse (ARFI) imaging can noninvasively identify lipid regions, that have been shown to increase a plaque's propensity to rupture, within carotid artery plaques <italic>in vivo</italic>. The work detailed herein describes …
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Mapping Myocardial Elasticity with Intracardiac Acoustic Radiation Force Impulse Methods
… on an intracardiac echocardiography transducer, acoustic radiation force methods may provide a useful means of characterizing the heart's elastic properties. Elasticity imaging may be of benefit for diagnosis and characterization of infarction and heart failure, as well as for guidance of …
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Directing acoustic radiation using a phased array of piezoelectric transmitters
This thesis presents an acoustic phased array system utilizing piezoelectric transducers. The system is capable of operating at arbitrary frequencies into the low megahertz range, with a trade-off between phase accuracy and operational frequency. A maximum of sixteen elements can be introduced to …
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Acoustic Radiation Force Impulse-Driven Shear Wave Velocimetry in Cardiac Tissue
<p>Acoustic radiation force impulses (ARFI) have been used to generated transverse-traveling mechanical waves in various biological tissues. The velocity of these waves is related to a medium's stiffness and thus can offer useful diagnostic information. Consequently, shear wave velocimetry has the …
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Active control of acoustic radiation due to discontinuities on thin beams
… were conducted to study the active control of acoustic radiation due to discontinuities on thin beams. One experiment investigated the radiation from a clamped end condition and the other investigated the radiation from a blocking mass. The beams were excited by subsonic flexural traveling …
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A study of acoustic radiation from an electrical spark discharge in air.
Massachusetts Institute of Technology. Dept. of Mechanical Engineering. Thesis. 1974. M.S.
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Prediction of Tonal Acoustic Radiation Due to Feedback-Loop Resonant Interactions in Transitional Airfoils
… the far-field noise propagation from the flow acoustic resonant interactions of the transitional airfoil. The Potential-Theoretic Method (PTM) as an advancement to traditional Kirchhoff methods is presented. The PTM eliminated the need to calculate the normal derivatives of pressure and an …
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Acoustic Radiation Force on a Fluid to Fluid Boundary by Phase Plate Focused Ultrasound
… the physics and applications of the ultrasonic radiation force at the interface between two immiscible fluids were investigated. These studies were performed using low-profile discrete-stepped lenses to the modify the phase of the incident radiation generating multiple field morphologies. In its …
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Assessment of Cardiac Function by Acoustic Radiation Force (ARF) Based Methods of Ultrasound Elastography
… measurement of cardiac function. </p><p>Acoustic radiation force (ARF) based ultrasound elastography techniques were developed in early 2000s and have been used to measure the static stiffness of tissue. These techniques are being used in the clinic for diagnosis of disorders and …
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Control of broadband acoustic radiation from structures using a piezoelectric double-amplifier active-skin
… is demonstrated for the reduction of broadband acoustic radiation from a vibrating structure. A simplified representation of the active-skin, employing acoustic monopoles as secondary sources, is explored as a precursor to the more complicated analyses of the device. Many design issues are …
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Finding the missing connection: diffusion-based tractography reconstruction of the acoustic radiation and other applications
… a notable omission in tractography studies: the acoustic radiation (AR), a major projection sensory pathway conveying auditory information from the thalamus to the auditory cortex. Topographical knowledge of this bundle is scarce, and its in-vivo tractography reconstruction remains challenging, …
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Optimal state estimation for the optimal control of far-field acoustic radiation pressure from submerged plates
… methodology for the suppression of far-field acoustic radiation pressure from submerged structures has been developed by Meirovitch (ref. 1). The linear modal state feedback control law developed implies that the full state (displacements and velocities) is available, perhaps through …
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Formation Process of Acoustophoretic Patterns
The acoustic radiation force is a nonlinear wave effect that exerts a non-zero time- averaged force on objects in the wave. In recent years, the acoustic radiation force has been widely explored for manipulating objects and small particles. These applications range from moving a few objects at a …
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High Resolution Acoustic Measurements of Musical Instruments
… work undertaken while carrying out research into acoustic measurement techniques for 3-dimensional acoustic radiation data for musical instruments, specifically when the instruments are being played by musicians. The original contribution to knowledge that is presented includes the development of …
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