Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 23 for “"ultrasonic techniques"”.
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Enhanced ultrasonic techniques for inspection of pressure tubes
… defects. Current inspection approaches utilising ultrasonic techniques are technically challenging due to transducer alignment caused by the tube dimensional changes. This Thesis focuses on enhancing ultrasonic techniques to improve the inspection accuracy by introducing signal processing …
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Locating the hip joint centre using ultrasonic techniques
… reduce errors associated with STA are promising techniques. This study focused on the use of ultrasound for locating the HJC and attempted to compare the results to the functional methods currently used for verification. Although a direct comparison could not be made between these two methods, it …
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Location of the hip joint centre using ultrasonic techniques
… magnitude of these parameters; yet current techniques still give inaccurate results.This study was therefore aimed at exploring the features of modern ultrasonography with a view to developing an accurate and convenient method of locating the HJC using medical ultrasound imaging.Five …
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The classification of slurries and other suspensions using ultrasonic techniques
The attenuation of ultrasonic waves travelling through a liquid containing a suspension of solids is highly dependent on frequency. At low frequencies, where the wavelength is long compared to the particle size, the particles move with the wave with some phase lag which gives rise to a loss …
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Characterization of high temperature creep in siliconized silicon carbide using ultrasonic techniques
Ultrasonic velocity and attenuation were both measured on samples containing various degrees of damage due to high temperature creep. These results were compared with parameters associated with creep damage such as strain and cavity formation, in order to better understand the mechanisms of creep …
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A feasibility study of PVDF piezoelectric sensors to detect damage in adhesive joints
… steps to design such sensors and proper techniques to attach them near the adhesive bondline. PVDF sensors have been successfully used as NDT transducers in pulse-echo, through-transmission, and acousto-ultrasonic techniques to monitor curing, to detect porosity and crack propagation in …
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An Ultrasonic Study of Trapped Hydrogen Tunneling Systems in Niobium and Tantalum
… H in Ta, and D in Nb have been studied with ultrasonic techniques at low temperature. Attenuation due to H in Ta was measured between 0.5 K and 10 K for frequencies between 10 MHz and 55 MHz. The sound velocity change due to H in Nb was measured in both the normal and superconducting state at …
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Signal processing techniques for ultrasonic inspection
… some of the limitations in present day techniques. Special interest has been given to ultrasonic examination techniques and the problems encountered when they are applied to thick welded plates. Some suggestions are given using signal processing methods. Chapter 2 treats the need for …
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Determination of Crispness in Breaded Fried Chicken Nuggets Using Ultrasonic Technique
… fried foods. In this study, the mechanical and ultrasonic techniques were used to determine crispness in breaded fried chicken nuggets under different storage conditions. The mechanical measurements have been made, using an Instron universal testing machine. An ultrasonic non-destructive …
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Polymer Gels: Kinetics, Dynamics Studies and Their Applications as Biomaterials
… polymer gel is investigated using turbidity and ultrasonic techniques. By probing movement of domains, a possible time-dependent gel structure in the spinodal decomposition region is presented. Theoretical studies of solution convection in gel matrix have been done and more analysis on …
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An ultrasonic study of trapped hydrogen tunneling systems in Nb and Ta
… H in Ta, and D in Nb have been studied with ultrasonic techniques at low temperature. Attenuation due to H in Ta was measured between 0.5 K and 10 K for frequencies between 10 MHz and 55 MHz. The sound velocity change due to H in Nb was measured in both the normal and superconducting state at …
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Nondestructive Detection of Hollow Heart in Potatoes Using Ultrasonics
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 …
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Ultrasonic nondestructive evaluation and imaging of defects in reinforced cementitious materials
… assessment of structures. Among many other NDE techniques, ultrasonic methods play a prominent role in the both quantitative and qualitative assessment of discontinuities in reinforced cementitious materials. Due to the heterogeneous nature of concrete, ultrasonic waves are highly scattered and …
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Nondestructive inspection and characterization of complex engineering materials via ultrasound techniques.
… For example, the aerospace industry uses such techniques to inspect aircraft components for damage prior to making a repair. The focus of the present dissertation is the development of ultrasonic techniques for inspecting highly attenuative materials. The first study presented in this work …
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Adaptive, High-Resolution Ultrasound Phased Array Imaging for use in the Inspection of Laser Brazed Joints in the Automotive Sector
… has been performed in several industries using ultrasonic phased array. In the automotive sector, many of the current standards for brazed joint inspection do not apply due to the high variations in surface geometry and limited accessibility to the inspection region. As the automotive industry …
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Dynamic performance of pre-cast prestressed beams – cast in-situ slab composite bridges
… failure occurs. Localized non-destructive techniques such as ultrasonic techniques, radar method, impact testing, magnetic based methods and proof load tests are limited to small areas, time consuming and require prior knowledge of the damaged zone. These limitations can be overcome by …
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Nanoparticle formation and coating using supercritical fluids
… is reduced by combining poor solvent and ultrasonic techniques. The first technique uses a proprietary co-axial ultrasonic nozzle to spray the solution suspension into the SC CO_2. Ultrasound is very effective in breaking agglomerates, and the introduction of the co-axial flow enables CO_2 …
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Ultrafast photo-acoustic spectroscopy of super-cooled liquids
Picosecond laser ultrasonic techniques for acoustic wave generation and detection were adapted to probe longitudinal and transverse acoustic waves in liquids at gigahertz frequencies. The experimental effort was designed for the study of supercooled liquids whose slower relaxation dynamics extend …
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Development of techniques for detection and dissolution enhancement of mineral deposits in petroleum pipelines using ultrasound.
… to address some of the above problems using ultrasonic techniques. Work presented in this thesis branches out into two main areas of interest, namely: (a) developments concerning location of deposits from both top-side and down-hole locations; and (b) developments relating to enhancement of …
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