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Showing 1 to 20 of 24 for “"Ultrasonic Attenuation"”.
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Ultrasonic attenuation in superconducting metals at radio and microwave frequencies
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1964.
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Ultrasonic Attenuation In As-Deposited Inconel 182 Weld Metal and Recommended Techniques for Discontinuity Evaluation.
… on a study of the problems associated with the ultrasonic evaluation of full penetration welds in pressure retaining bi-metallic and tri-metallic joints involving as-deposited austenitic weld material. The weld joint design was one simulating a component on a nuclear reactor known as a …
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Nondestructive inspection of load induced damage in fiber reinforced polyphenylene sulfide
… testing methods, including C-scan, ultrasonic attenuation, acoustic emission, X-ray radiography, and edge replication, were applied to study the damage developed under quasi-static tension loading of this material. The C-scan, edge replication, and X-ray radiography tests were …
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Low Temperature Electron Irradiation Induced Defects in Gallium-Arsenide: Bulk and Surface Acoustic Wave Studies
… temperatures below 190 K produces two peaks in ultrasonic attenuation versus temperature. The defects responsible for both peaks have trigonal symmetry and were observed in n-type and semi-insulating GaAs with bulk and surface acoustic waves (SAW) respectively. Bulk waves at eight frequencies …
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Ultrasonic propagation in cancellous bone
… and the second is the evaluation of existing ultrasonic theories in attempt to apply them to the propagation in cancellous bone. The work is related to a new technique which uses ultrasonic attenuation to measure and predict osteoporosis, especially in the elderly population.The ultrasonic …
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An Ultrasonic Study of Impurity-Interstitial Complexes in Electron Irradiated Aluminum-Silicon and Aluminum-Silver
Ultrasonic attenuation and velocity measurements were performed to probe the structure and annealing behavior of solute self interstitial complexes in electron irradiated (T -monoclinic defect symmetry is present. The annealing, during Stage II, of this defect species follows a first order rate …
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An ultrasonic study of impurity-interstitial complexes in electron irradiated Al-Si and Al-Ag
Ultrasonic attenuation and velocity measurements were performed to probe the structure and annealing behavior of solute self interstitial complexes in electron irradiated (T < 70 K) dilute Al-Ag and Al-Si alloys. In both alloy systems, a similar attenuation peak structure is observed. This peak …
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Transport properties of anisotropic superconductors
… source of scattering. The experimental data on ultrasonic attenuation and thermal conduction in the superconducting phase of UPt3 do not behave as one would expect if the electron-impurity phase shift were small, and therefore, assuming electron-impurity scattering to be the dominant process, we …
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Topics in transport phenomena near the critical point
… transition and to the calculation of the attenuation coefficient for longitudinal sound waves near the magnetic transition. The rise in the electrical conductivity as a material approaches its superconducting transition is described. Near T c small regions become superconducting and can …
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An ultrasonic study of trapped hydrogen in niobium
… of the model. Measurements have been made of ultrasonic attenuation and velocity in the Nb-O-H system as a function of temperature, frequency, polarization and isotope. In addition to the previously found stable peak, an additional peak is found when the specimen is cooled rapidly. The peak …
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Interstitial-impurity trapping in Al-Fe and Al-Zn
Ultrasonic attenuation and velocity measurements were made as a function of polarization, temperature, frequency and annealing before and after electron irradiation near 65K of A1-Fe and A1-Zn dilute alloys. Multiple relaxation processes were observed in both alloys. In the case of A1-Zn, the …
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Elementary excitations in heavy-fermion superconductors
… in the polar state. Secondly, the specific heat, ultrasonic attenuation and thermal conductivity that result from the qausiparticle excitations out of such states are calculated. The gapless states of the axial and polar type produce low temperature power laws for these quantities that reflect the …
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Bias stress detection of dislocation resonance in lead
Measurements of the ultrasonic attenuation and velocity and their changes with bias stress are used to test theories of bias stress effects by Hikata, Johnson, and Elbaum (HJE). Hikata amd Elbaum (HE), Alefeld, and one presented here. The only theory which survives the test and is supported by …
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Low temperature electron irradiation induced defects in gallium arsenid: Bulk and surface acoustic wave studies
… temperatures below 190 K produces two peaks in ultrasonic attenuation versus temperature. The defects responsible for both peaks have trigonal symmetry and were observed in n-type and semi-insulating GaAs with bulk and surface acoustic waves (SAW) respectively.· Bulk waves at eight frequencies …
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Universal sound attenuation in amorphous solids at low-temperatures
… temperatures, the most striking of which is the ultrasonic attenuation coefficient 1/Q(ω). The established theory of tunneling two state systems (TTLS) in its original form (i.e. without extra fitting functions and parameters) is unable to explain this universality. While the TTLS model can be …
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Evaluation of the accuracy and precision of ultrasound attenuation slope estimates
… and enables quantitative ultrasound imaging. The ultrasonic attenuation is a quantitative parameter that can be used to characterize tissue. Furthermore, for any scatterer size estimations, the spectral distortions caused by attenuation need to be corrected, and therefore the attenuation has to be …
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Interstitial-impurity interactions in copper-silver and aluminum-magnesium alloys
… and copper. Measurements were taken of the ultrasonic attenuation (at 10 and 30 MHz) and resonant frequency (at 10 MHz) in single crystal sample s of Cu-Ag and AI-Mg. A variety of peaks appeared in both materials in plots of the logarithmic decrement versus temperature. The simultaneous …
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Investigation of constraint effects on flaw growth in composite laminates
… specimens. These techniques include replication, ultrasonic c-scan, ultrasonic attenuation, acoustic emission, x-radiography, thermography and stiffness measurement. The effects of constraint on the response of composite materials can be classified in two categories: (a) in-plane effects and (b) …
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Control and qualification of titanium welds
… titanium and one of its alloys (Ti-6Al-4V) by ultrasonic means and qualiFying the metals in the as-welded condition in terms of their grain sizes and mechanical properties. The alignment and symmetry of the weld pools were successfully tested by using ultrasonic shear waves. The grain sizes at …
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Effects of anisotropy of the superconducting energy gap
… tunneling, surface resistance, and longitudinal ultrasonic attenuation are more sensitive to the details of the anisotropy than are the above thermodynamic properties. Theoretical expressions which explicitly include the anisotropy of a general gap parameter are given for these processes. In …
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