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Dissertations / Theses on the topic 'Ultrasonics'

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Published: 4 June 2021
Last updated: 28 July 2024

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1

Tu, Juan. "Fundamental aspects of ultrasound contrast agent dynamic behaviors and inertial cavitation quantification /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8122.

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2

Kreider, Wayne. "Gas-vapor bubble dynamics in therapeutic ultrasound /." Thesis, Connect to this title online; UW restricted, 2008. http://hdl.handle.net/1773/8074.

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3

Anand, Ajay. "Noninvasive temperature estimation technique for HIFU therapy monitoring using backscattered ultrasound /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/5867.

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4

Skilbeck, Mark. "Ultrasonics and nanomechanics." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/91770/.

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Since its invention, atomic force microscopy (AFM) has been a valuable tool for probing sample surfaces on the nanoscale, particularly the topography and the mechanical properties. This thesis investigates a subset of techniques focussed on measuring mechanical properties, particularly those which combine AFM with ultrasound. First, a nanoindentation technique is used to measure the mechanical properties (2D elastic modulus and breaking load) of suspended 2D materials. Graphene grown by chemical vapour deposition (CVD) is tested and found to have similar mechanical properties to previously reported values for mechanically exfoliated graphene. The CVD grown graphene is then functionalised by exposure to atomic oxygen, significantly affecting the mechanical properties, making the sheets both softer and weaker, becoming comparable to the properties of graphene oxide. Comparison with the changes in atomic structure suggests that these changes in mechanical properties are likely caused by the creation of extended topological defects. Such 2D materials are of interest as ultrasonic nanoresonators, for which the resonant behaviour could potentially be investigated using AFM. Ultrasonic force microscopy (UFM), a technique where the sample is oscillated at frequencies far greater than the cantilever resonance to provide a channel with contrast due to local surface stiffness, is also investigated. By combining experiment and simulation, the influence of experimental conditions on the observed response is studied and the challenges to obtaining quantitative results (e.g. the Young’s modulus) are discussed. The combination of UFM with other contact mode AFM techniques, such as conductive AFM and friction force microscopy, is demonstrated for the first time, presenting an unusual ability to acquire multimodal information in a single pass. The combination is also shown to benefit from the superlubricity effect of UFM, using it to conductively image a delicate carbon nanotube network. Finally, the use of an AFM as a detector for ultrasonic non-destructive testing, where the interaction of ultrasonic waves with sample features is used to probe a sample, is demonstrated. Test measurements are performed on a simple aluminium plate sample with a laser micro-machined slot and compared to results gathered using traditional detectors (piezoelectric transducers and laser interferometers), showing similar signal features. The advantages and disadvantages of AFM detection are discussed, with the high spatial resolution being the primary advantage. The capability to detect in-plane surface motion using the AFM’s lateral channel is demonstrated, allowing for simultaneous and distinct measurement of two components (one in-plane component and the out-of-plane motion) of the surface, which is not easily achieved using traditional ultrasonic detection methods.
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5

Nadkarni, Aditya. "Reflector geometry specific modeling of an annular array based ultrasound pulse-echo system." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-091207-114218/.

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6

Nicholson, Nicholas C. "Waveguides in medical ultrasonics." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/19191.

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Waveguides occur in a number of areas of medical ultrasonics, one important application being in sonically-sensitive biopsy-needles. The behaviour of the propagation of ultrasound in waveguides is not widely understood. A model of guided sound-wave propagation in the elastic limit, based on Pochhammer's theory, is described. Characteristic equations for both real and imaginary arguments are derived for isotropic solid and hollow cylindrical waveguides and also for transversely-isotropic solid cylindrical waveguides. These equations, which take the form of singular determinants, were solved numerically. The solutions reveal that waveguides are dispersive media and the group and phase velocities of various modes of propagation are presented. In addition, the particle displacements of some of these modes are illustrated. Group velocities of modes in waveguides of different material were measured experimentally using an ultrasound pulse technique and the experimental results are compared with theory. Attenuation of the more dominant modes of propagation was also measured over the frequency range 1.0-5.0 MHz and the phenomenon of selective attenuation is discussed in the light of a number of attenuation models. A systematic study of sound conduction in a variety of waveguides of different radii and material media was undertaken and the effect of heat treatment investigated. The changes in conduction introduced by the latter are explained by changes in the internal grain structure which were observed using methods of metallurgical analysis. Finally, sound propagation was examined for conditions similar to those encountered in biopsy-needle guidance techniques. Other possible applications of waveguides in the field of medical ultrasonics are also considered. These theoretical and experimental studies have provided a fuller understanding of mode propagation in waveguides used in medical ultrasonics.
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7

Barrett, George Alexander. "Kinesiographic lesion monitoring (KLM) /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/6026.

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8

Wu, Chung Hao. "DETERMINATION OF BLADDER VOLUMES BY MICROPROCESSOR BASED ULTRASONIC SYSTEM." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275392.

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9

Carr, Hilary. "Electrostatic transducers for airborne ultrasonics." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254254.

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10

Kuang, Wen-Tao. "Robot tracking with advanced ultrasonics." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339960.

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11

Kotopoulis, Spiros. "Biomedical ultrasonics, cavitation, and sonoporation." Thesis, University of Hull, 2011. http://hydra.hull.ac.uk/resources/hull:4746.

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This thesis treats biomedical ultrasonics, cavitation and sonoporation. Focussed ultrasound surgery can heat tissue to a temperature that causes protein denaturation and coagulative necrosis. For high-resolution focused ultrasound microsurgery, high working frequencies are necessary. We manufactured a highfrequency, high-intensity focussed ultrasound transducer, using lithium niobate as the active element. The transducer was capable of creating 2.5×3.4 (mm)2 lesions without affecting surrounding tissue. Such disruptive effects of ultrasound also have applications outside medicine. Since cyanobacteria contain gas vesicles, we hypothesised that these can be disrupted with the aid of ultrasound. During 1-hour sonication in the clinical diagnostic range, we forced blue-green algae to sink, thus promoting natural decay. In medical diagnostics, ultrasound contrast agents are added to the blood stream to differentiate between blood and other tissue types. We injected such lipid-shelled microbubbles into a synthetic capillary and sonicated using continuous ultrasound. The microbubbles formed clusters at a quarter wavelength apart owing to radiation forces. We observed cluster coalescence and translation towards the capillary wall. To study acoustic cavitation, we designed and built a scientific instrument combining a pulsed laser and a high-intensity focussed ultrasound transducer, capable of nucleating at precise locations. The cavitation dynamics were recorded using highspeed cameras. At high acoustic intensities, interacting cavitation clouds were formed. Microbubbles under sonication have been observed to create transient pores in adjacent cell membranes. This so called sonoporation has been associated with highly non-linear bubble phenomena. We observed lipid-shelled microbubbles near cancer cells under quasi-continuous low-amplitude sonication. Typically within a second of sonication, microbubbles were seen to enter the cells and dissolve. This new explanation of sonoporation was verified using high-speed photography and confocal fluorescence microscopy. If drug and genes can be successfully coupled to acoustically active vehicles, sonoporation might revolutionise non-invasive therapy as we know it.
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12

Sikdar, Siddhartha. "Ultrasonic imaging of flow-induced vibrations in tissue /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6100.

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13

Mehra, Sumat. "Frequency modulated pulse for ultrasonic B-scan imaging in attenuating medium /." Online version of thesis, 1991. http://hdl.handle.net/1850/11641.

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14

Xu, Xu. "Closed-space structure reconstruction based on ultrasound." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3950625.

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15

Guldiken, Rasim Oytun. "Dual-electrode capacitive micromachined ultrasonic transducers for medical ultrasound applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31806.

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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Degertekin, F. Levent; Committee Member: Benkeser, Paul; Committee Member: Berhelot, Yves; Committee Member: Brand, Oliver; Committee Member: Hesketh, Peter. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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16

陳鳳儀 and Fung-yee Chan. "Doppler ultrasound is a useful investigatory tool in the field of obstetrics & gynaecology." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31981525.

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17

Bermúdez, Luz Daniela. "Nonthermal processing of milk." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Dissertations/Spring2008/l_bermudez_041508.pdf.

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18

Codron, Fabien. "Detection of surface waves in the ground using an acoustic method." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17396.

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19

Vogt, Thomas Karl. "Determination of material properties using guided waves." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273280.

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20

O'Donovan, T. L. "Signal processing and pseudo-random binary sequences." Thesis, Bangor University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307237.

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21

Lewis, Jamie Peter. "Three dimensional simulation of ultrasonic cleaning vessels and verification of results." Thesis, University of South Wales, 2007. https://pure.southwales.ac.uk/en/studentthesis/three-dimensional-simulation-of-ultrasonic-cleaning-vessels-and-verification-of-results(57bd54ba-4140-4179-8a6a-7297f154cb40).html.

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Ultrasonics, that is mechanical waves with a frequency greater that 18 kHz. are employed in a number of diverse and distinctive industries. One important niche occupied by ultrasound, and the focus of this thesis, is its application in ultrasonic cleaning systems whereby the rapid pulsing of mechanical waves at ultrasonic frequencies forms thousands of microscopic voids (or cavities) in the liquid. It is the implosions of these voids during the positive pressure phase of the wave that assists th removal of contaminants from the surface of an immersed load and is known as cavitation. A thorough literature review conducted as the foundation of this work uncovered a significant deficit in knowledge regarding the positions of cavitating fields within ultrasonic vessels. Further to this, the effects on the cavitating field of a number of industrially relevant parameters, such as transducer placement. the introduction of baskets and cleaning loads to the liquid and variations in the level of the cavitating medium, were found to be deficient within both academic and industrial knowledge base. The outcomes of the literature review clearly indicated that it was evident that the development of a "toolset" capable of modelling the bulk cavitating fields within ultrasonic vessels would not only sustain the strong industrial relevance of the programme of work, but would also add significantly to extant knowledge concerning the design and production of commercial ultrasonic vessels. This work describes the development of such a toolset, detailing the mathematical modelling behind the simulation system and the logical progression of the work, from basic 2D models used for rapid prototyping to full 3D models used to simulate a wide variety of complex systems with parameters hitherto un-described within the literature. A variety of methods of quantifying the simulation outputs are reviewed and discussed during the thesis, leading to the logical selection of one qualitative and one quantitative indicator of cavitating fields. A comparison of the simulation outputs to the respective empirical data showed an excellent degree of con-elation, leading to a high level of confidence in the simulation toolset. Use of the verified model together with the developed design methodology was used to address the industrially relevant issues detailed in the literature review and this further promoted the contribution to knowledge presented in this work. As in any industrial design. pragmatic approximations were used in the production environment and this occasionally appeared to show discrepancies between the simulation outputs and the practical data obtained. Specific causes behind these differences are critically analysed. and along with further questions arising from such analysis. The outcomes formed the backbone of a future work proposal presented along with a comprehensive review and summary of the results and improved synthesis techniques.
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22

Sahin, Ali. "Nonlinear pressure fields due to focused rectangular apertures in water." Thesis, University of Bath, 1992. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305309.

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23

Schlicher, Robyn Kathryn. "Mechanistic Features of Ultrasound-Mediated Bioeffects." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/14149.

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The inability to transport molecules efficiently and easily into cells and across tissues is one of the major limitations of developing drug delivery systems. A novel approach to overcoming this problem could be the use of low-frequency ultrasound to make cell membranes and tissues more permeable. Previous studies show that normally impermeant molecules can be transported into cells exposed to ultrasound; however, the mechanism by which this occurs is not well understood. Our hypothesis is that low frequency ultrasound can reversibly disrupt membrane structure, thus allowing diffusion-driven intracellular delivery of molecules through a breach in the cell membrane. The effects of ultrasound are not limited to uptake of molecules; there can also be significant loss of cell viability after sonication. Therefore, the focus of this work is to determine the mechanisms by which molecular uptake and cell death occur from ultrasound exposure. The long-term goal of this work is to increase the number of viable cells that experience uptake by controlling the effects that cause cell death. Our data have show that large molecules (r ≤ 28 nm) can be taken into cells after exposure to 24 kHz (10% duty cycle for 2 s of exposure time at 0.1 pulse length over a range of pressures) ultrasound and that uptake of these molecules can occur even after sonication ended. In experiments developed to isolate the mechanism(s) of uptake, DU145 prostate cancer cells depleted of ATP energy and intracellular calcium showed no uptake of calcein, a small fluorescent molecule (MW = 623 Da), nor did sonicated lipid bilayers (red blood cell ghosts), suggesting that uptake is calcium mediated and requires active mechanisms in viable cells. Multiple types of microscopy, including electron and laser scanning confocal, showed evidence of large plasma membrane disruptions which support the hypothesis that transport of molecules into cells occurs through repairing wounds. Microscopy studies also indicated that much if the sonication-mediated death can occur by instantaneous cellular lysing and rapid cell death (within minutes post-exposure) due to wound-instigated necrosis; in addition, characteristics of rapidly induced controlled death modes were seen and found to be non-caspase-mediated within an hour after sonication ended.
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24

Tanary, Samsir. "Characterization of adhesively bonded joints using acousto-ultrasonics." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/22413.

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25

Chand, Priyanka. "Enhancing biodiesel production from soybean oil using ultrasonics." [Ames, Iowa : Iowa State University], 2008.

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26

Sun, Ke. "Sample preparation and ultrasonic measurement of phononic crystal /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202007%20SUN.

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27

林正乾 and Ching-kin Lam. "Oxidation reaction of unsaturated long chain fatty esters: a sonochemical approach." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31212384.

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28

Hibberd, David. "Use of ultrasound to characterise polymer induced flocculation." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267709.

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29

Brock, Sheila Anne. "The role of obstetric ultrasound in primary health care at a secondary hospital in South Africa." Thesis, Peninsula Technikon, 2000. http://hdl.handle.net/20.500.11838/1558.

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Thesis (MTech (Radiography))--Peninsula Technikon, Cape Town, 2000
Ultrasound has, until recently, been regarded as a sophisticated diagnostic modality, reserved for tertiary health care. In reality, it is a cost-effective, reliable and safe modality that is highly suited to primary health care. Secondary level centres provide the only access to ultrasound for many of the obstetric primary health care patients, as primary health care has limited ultrasound resources. The increasing monthly statistics, at one secondary centre, bares witness to the need for ultrasound in primary health care. At the time of this study ultrasound scans were not routine for every obstetric patient. Experience indicates that only the patients who clinically suggest a possible risk are referred for ultrasound to confirm, or rule out problems. However, there are a number of complications, which have little or no early clinical indications. [Palmer, 1995:285] This means that many of the problems encountered are often in late gestation and they have a marked bearing on the obstetric management of the patient. This was a retrospective study, of approximately 1000 patients attending an ultrasound department at a secondary centre. Most of the obstetric patients that were sent for an ultrasound examination came from the primary health care centres in the region.
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30

Durbin, Sharon A. "Understanding the effects of obstetrical ultrasound." Online version, 1999. http://www.uwstout.edu/lib/thesis/1999/1999durbin.pdf.

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31

Lam, Ching-kin. "Oxidation reaction of unsaturated long chain fatty esters : a sonochemical approach /." [Hong Kong] : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14777460.

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32

Hutcheson, Joshua Daniel. "Quantification and control of ultrasound-mediated cell death modes." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29768.

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Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Prausnitz, Mark; Committee Member: Bommarius, Andreas; Committee Member: Jones, Christopher; Committee Member: Sambanis, Athanassios. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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33

Anhalt, Dennis Paul 1960. "MODIFICATION OF A DIAGNOSTIC ULTRASOUND UNIT'S MOVEMENT SYSTEM TO PERFORM SCANNING DURING FOCUSSED, ULTRASOUND HYPERTHERMIA." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275546.

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34

Johnson, Charles Alan 1957. "A CONTROL SYSTEM FOR THE APPLICATION OF SCANNED, FOCUSSED ULTRASOUND IN HYPERTHERMIA CANCER THERAPY." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276438.

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35

Husby, Oddvar. "High-Level Image Models with Application to Medical Ultrasonics." Doctoral thesis, Norwegian University of Science and Technology, Department of Mathematical Sciences, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1996.

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36

Cohen, Joseph P. "Digital calculation of real time velocity profiles using ultrasonics." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/17977.

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37

Loupas, Thanasis. "Digital image processing for noise reduction in medical ultrasonics." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/19060.

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38

Pye, Stephen Dominic. "Medical ultrasonics : adaptive time gain compensation in diagnostic imaging." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/29955.

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39

Jivanuwong, Solos. "Nondestructive Detection of Hollow Heart in Potatoes Using Ultrasonics." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36671.

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Ultrasonic techniques were used to detect hollow heart in potatoes nondestructively. Fifty Russet Burbank potatoes were evaluated physically and sonically. A pair of dry-coupling 50-kHz ultrasonic transducers were used to generate an ultrasonic pulse with a power level of 0.22 W for the test of acoustic transmission through whole potato tuber in a transverse direction at different locations along the longitudinal axis with a certain interval distance. It was found that the waveform analyses in time domain for a series of transmitted signals along the longitudinal axis of potato tuber, yielded the potential in detecting hollow heart in potatoes noninvasively. The transmission losses for potatoes having hollow heart were found to be greater than 0.28 dB/mm. This value was used as a criterion to indicate potatoes with hollow heart at an accuracy of 98 percent. The ability to detect hollow heart in potatoes was limited to a minimum cavity size of 0.5 cm3 because the interval distance between locations of measurement was relatively large compared to the size of the projected area of hollow heart. The accuracy of the detection would be improved if a smaller contact area for the transmitting transducer were used, and if the intervals between ultrasonic measurement locations were smaller.

Physical properties of the tested potatoes were also recorded for consideration of their relationships with ultrasonic parameters. Physical properties of tested potatoes such as modulus of elasticity, tuber length, diameter, and weight, were found to have poor correlation with ultrasonic parameters such as ultrasonic velocity, attenuation coefficient, and root mean square voltage of transmitted signal. This study showed that if all potatoes with weights of 300 g or less were eliminated from a mass of incoming potatoes, only 80 percent of the total mass would have to be examined for hollow heart.
Master of Science

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40

McClements, David Julian. "The use of ultrasonics for characterising fats and emulsions." Thesis, University of Leeds, 1988. http://etheses.whiterose.ac.uk/324/.

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Ultrasonics has not found widespread use in the food industry, despite having considerable potential for characterising food materials. This is due to the complexity and diversity of food materials, the lack of suitable instrumentation and a poor understanding of how ultrasound interacts with many food components. In this work it is shown how a good appreciation of the theories describing ultrasonic propagation in heterogeneous materials, coupled with careful experimental design, leads to many new applications of ultrasonics for characterising fats and emulsions. Ultrasonic measurements were made using either a pulse echo technique (1-10MHz), or a pulse echo interferometric technique (5-55MHz). The ultrasonic velocities of a series of 0-30% w/w glyceride/oil mixtures and some commercial fats were measured with varying temperature (0-70°C) at 1MHz. Ultrasonic scattering was not important in these systems and so empirical equations or simple (SFC) theoretical formulae could be used to relate the measured velocities to the solid fat contents (SFC) of the samples. There were very significant correlations between the SFCs determined using ultrasonics and those determined using pulsed NMR (r > 0.99), and so ultrasonics should prove a useful adjunct or alternative to NMR. Velocity measurements also proved useful for characterising vegetable oils since the velocity of an oil could be related to its glyceride composition. The ultrasonic velocity and attenuation of a series of sunflower oil and water emulsions mean were measured with varying frequency (1-55MHz) mean, droplet size (0.1-0.9μm), disperse phase mass fraction (0-0.5) and emulsion type (0/W and W/O). Scattering was significant in these emulsions and could be used to measure their disperse phase mass fractions and particle size distributions. Ultrasonics has important advantages over existing techniques for this type of measurement since it can be used in emulsions which are optically opaque, in a non-intrusive, non-invasive manner.
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41

Russell-Floyd, Richard S. "Acoustic emission and acousto-ultrasonics on aromatic polymer composites." Thesis, University of Bath, 1991. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293342.

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42

Kranz, Michael S. "Micro-mechanical sensor for the spectral decomposition of acoustic signals." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39496.

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An array of electret-biased frequency-selective resonant microelectromechanical system (MEMS) acoustic sensors was proposed to perform analysis of stress pulses created during an impact between two materials. This analysis allowed classification of the stiffness of the materials involved in the impact without applying post-impact signal processing. Arrays of resonant MEMS sensors provided filtering of the incident stress pulse and subsequent binning of time-domain waveforms into frequency-based spectra. Results indicated that different impact conditions and materials yielded different spectral characteristics. These characteristics, as well as the resulting sensor array responses, are discussed and applied to impact classification. Each individual sensor element in the array was biased by an in situ charged electret film. A microplasma discharge apparatus embedded within the microsensor allowed charging of the electret film after all device fabrication was complete. This enabled electret film integration using high-temperature surface micromachining processes that would typically lead to discharge of traditionally formed electret materials. This also eliminated the traditional wafer-bonding and post-fabrication assembly processes required in conventional electret integration approaches. The microplasma discharge process and resulting electret performance are discussed within the context of the MEMS acoustic sensor array.
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43

Eljaaidi, Abdalla Agila. "2D & 3D ultrasound systems in development of medical imaging technology." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2193.

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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.
Ultrasound is widely used in most medical clinics, especially obstetrical clinics. It is a way of imaging methods that has important diagnostic value. Although useful in many different applications, diagnostic ultrasound is especially useful in antenatal (before delivery) diagnosis. The use of two-dimensional ultrasound (2DUS) in obstetrics has been established. However, there are many disadvantages of 2DUS imaging. Several researchers have published information on the significance of patients being shown the ultrasound screen during examination, especially during three- and four-dimensional (3D/4D) scanning. In addition, a form of ultrasound, called keepsake or entertainment ultrasound, has boomed, particularly in the United States. However, long-term epidemiological studies have failed to show the adverse effects of ultrasound in human tissues. Until now, there is no proof that diagnostic ultrasound causes harm in a human body or the developing foetus when used correctly. While ultrasound is supposed to be absolutely safe, it is a form of energy and, as such, has effects on tissues it traverses (bio-effects). The two most important mechanisms for effects are thermal and non-thermal. These two mechanisms are indicated on the screen of ultrasound devices by two indices: The thermal index (TI) and the mechanical index (MI). These are the purposes of this thesis: • evaluate end-users’ knowledge regarding the safety of ultrasound; • evaluate and make a comparison between acoustic output indices (AOI) in B-mode (2D) and three-dimensional (3D) ultrasound – those measured by thermal (TI) and mechanical (MI) indices; • assess the acoustic output indices (AOI) to benchmark current practice with a survey conducted by the British Medical Ultrasound Society (BMUS); and • review how to design 2D and 3D arrays for medical ultrasound imaging
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44

Banker, Christian J. "Interactive Training System for Medical Ultrasound." Worcester, Mass. : Worcester Polytechnic Institute, 2009. http://www.wpi.edu/Pubs/ETD/Available/etd-021709-121801/.

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45

Herrmann, Jan. "Generation and Detection of Higher Harmonics in Rayleigh Waves Using Laser Ultrasound." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7475.

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This research studies higher harmonics of Rayleigh surface waves propagating in nickel base superalloys. Rayleigh waves are used because they carry most of the energy and travel along the surface of a specimen where fatigue damage is typically initiated. The energy concentration near the free surface leads to stronger nonlinear effects compared to bulk waves. An ultrasonic piezoelectric transducer together with a plastic wedge is used for the experimental generation of the Rayleigh wave. The detection system consists of a laser heterodyne interferometer. Measurements are performed to detect the fundamental wave as well as the second harmonic. The amplitude ratio is related to the nonlinearity parameter beta which is typically used to describe changes in microstructure and investigate fatigue damage.
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46

Turner, A. T. "The use of ultrasonic irradiation for the modification of chemical reactivity." Thesis, Coventry University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379786.

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47

Hardcastle, J. L. "Novel voltammetric methods in heavily passivating media." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:7ef17e49-dd12-4c3b-b2a0-b94605ccb1fa.

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The work contained in this thesis demonstrates that the introduction of power ultrasound into electrochemical systems can broaden the scope of techniques such as anodic stripping voltammetry. Analysis is facilitated by the well-documented phenomena associated with ultrasound, cavitation and acoustic streaming. Cavitation is caused by the collapse of voids created by ultrasonic compression and rarefaction of the solution and results in both localised high temperatures and pressures in the bulk solution and microjetting on the surface. Precise mechanistic details are still open to debate but there is evidence to suggest that shear forces at the interface when the electrode is flushed are responsible for removing organic material (particularly large species such as proteins) facilitating continuous cleaning and activation of the surface. Acoustic streaming has been shown to give diffusion layer thicknesses of the order of 1-10 μm depending on solvent and ultrasound power. The increased mass transport at such low diffusion layer thicknesses results in shorter preconcentration periods in electrochemical stripping voltammetry, greater sensitivity and a correspondingly lowered detection limit. Often ultrasound has been applied to highly passivating systems where conventional silent electroanalysis fails with the effect of transforming invisible or tiny voltammetric signals into large and quantitative responses suitable for sensitive and accurate analytical purposes. In Section IIthe relative contributions of acoustic streaming and cavitationally induced microjetting to the sonovoltammetric response is assessed. Chronoamperometry at insonated electrodes of both micro and macro dimensions, and differential pulse voltammetry (DPV) were used to explore the frequency and violence of cavitational events and the nature of the diffusion layer prevailing under steady-state electrolysis. The results lead to a physical model of an insonated electrode which may be described as a steady diffusion layer a few microns thick brought about by acoustic streaming which is occasionally and randomly punctuated by a cavitational event. The frequency and violence of the event is dependent on the solvent and ultrasound power, except at very short electrode-to-horn separation where the cavitational contribution becomes substantial. Section II concentrates on the implementation of the technique with applications to the detection of heavy metals in biofluids. In Chapter 4 sonoelectroanalysis is applied to the detection of copper bound within human blood protein and whole blood. It is shown that the enhancement of square wave anodic stripping peaks observed in ceruloplasmin and whole blood is not simply due to mass transport enhancement and cavitational cleaning effects alone but also the liberation of copper from the active sites in which it is bound prior to preconcentration. The results of a quantitative determination of total copper in two samples of whole blood were 1300 μg L-1 and 620 μg L-1, verified by independent blind analysis using atomic absorption spectroscopy (AAS). The need for rapid analysis of environmental samples can also be fulfilled using sonoelectroanalysis. In Chapter 5 fish gill mucus is used as a non-destructive biomarker for the detection of heavy metals by sono-square wave anodic stripping voltammetry (sono-SWASV). A quantitative assessment of copper content yielded values of 16 μgL-1 and 21 μgL-1 which compared favourably with independent blind analysis by AAS. The potential of the technique for detection of other heavy metals for example lead, was also demonstrated. Lead poisoning is recognized as a major environmental health risk and in Chapter 6 quantitative analysis of lead in artificial saliva from a realistic sputum volume, 220 μL, introduced to acetate buffer is investigated. An insonated preconcentration obviates the need for lengthy or degradative sample pretreatment by liberating the lead from the glycoproteins and other materials to which it binds in solution. Quantitative depassivation of the electrode surface by cavitational shearing maintained the analytical signal throughout the experiment where under silent conditions the signal diminished to zero with time. The detection limit in the analyte is 0.25 μg L-1. Following this proof of concept, Chapter 7 goes on to apply the technique to the quantitative determination of lead and cadmium in real human saliva. Close agreement between lead concentration determined by sono-SWASV and independent and blind ICP-MS is reported for human saliva samples with detection limits of 0.5 μg L-1 lead and 1 μg L-1 cadmium in saliva. Section IV harnesses the benefits of acoustic emulsification. Power ultrasound is capable of forming droplets of micron dimensions with lower energy consumption than conventional emulsifiers. Chapter 8 acoustic emulsification is employed in the detection of vanillin (4-hydroxy-3-methoxybenzaldehyde) in vanilla essence using ethyl acetoacetate as a novel electrochemical and sonoelectrochemical solvent. Contrasting with silent voltammetry, ultrasound facilitates emulsification and extraction of vanillin in the extract permitting an analytical square wave voltammetric signal to be obtained. Close agreement with a blind analysis of the samples using HPLC-UV is observed with a limit of detection in the biphasic medium of 0.020 mM. In Chapter 9 acoustic emulsification is utilized in the solvent extraction of copper. Ultrasonic emulsification of an aqueous phase containing copper ions with the N-benzoyl-N-phenyl-hydroxylamine ligand in an organic ethyl acetate phase was shown to facilitate the extraction of copper into the organic phase at 25°C. Subsequent emulsification with 1 M acid "back-extracts" or "re-strips" the copper into the aqueous phase prior to analysis via sono-SWASV. The technique necessarily removes contaminants present in the test solution since these will prefer to remain in the initial aqueous phase, or will transfer to the organic phase but are unlikely to be doubly transferred into the "clean" final aqueous phase. In Chapter 10 the technique is applied to the analysis of copper in the soft drink "Ribena® Light" with a detection limit of 2 μg L-1 and copper in blood with a detection limit of 0.16 μg L-1. In the latter case the analysis required a sample volume of 100 μL suggesting that a pinprick test may be feasible. Finally in Section V, the analysis of copper in the presence of surfactants is investigated. Surfactant adsorption has been shown to have a passivating effect on the electrode surface during anodic stripping voltammetric measurements. Effluent, both industrial and domestic, is commonly contaminated with surfactant and electroanalysis of heavy metals is frequently precluded. It is therefore desirable to formulate a new analytical strategy in waste water. This is facilitated by controlled experiments with known amounts of anionic, cationic or neutral surfactant which also provides an ideal model system for comparing the techniques introduced in earlier Chapters. "Direct" sonoelectroanalysis in the medium of interest is compared with biphasic sono-solvent double extraction and both are appraised in the light of novel sonotrode technology. This thesis concludes that sonoelectroanalysis is a powerful and versatile analytical tool that can be employed in an expanding range of applications. The examples given herein are pertinent to the major fields of medical diagnosis and the assessment of environmental pollution. They demonstrate that sonoelectroanalysis is a viable alternative to conventional analytical techniques which have the disadvantages of more lengthy sample pretreatment and cost.
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48

Marshall, Thomas. "Instrumentation for the control of the formation of industrial particulate mixtures, and their real-time monitoring by ultrasound." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311819.

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49

Granville, R. K. "The ultrasonic behaviour of titanium alloys." Thesis, Bucks New University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373580.

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50

Webb, Chadleo Allan. "The effect of piezoelectric and magnetostrictive scaling devices ontreatment outcomes." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429888732.

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