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3 edition of The role of the reflection coefficient in precision measurement of ultrasonic attenuation found in the catalog.

The role of the reflection coefficient in precision measurement of ultrasonic attenuation

The role of the reflection coefficient in precision measurement of ultrasonic attenuation

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Published by Lewis Research Center in Cleveland, Ohio .
Written in English

    Subjects:
  • Ultrasonics

  • Edition Notes

    StatementEdward R. Generazio ; prepared for the 1984 Annual Review of Progress in Quantitative Nondestructive Evaluation sponsored by the Defense Advanced Research Projects Agency (DARPA), LaJolla, California, July 8-13, 1984
    SeriesNASA technical memorandum -- 83788
    ContributionsLewis Research Center
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL14926071M

    Low accuracy in ultrasonic pulse-echo attenuation measurements may be another reason. Ultrasonic diffuse field decay rate measurements offer a new method for internal friction assessment. The method applies in the frequency range from about to MHz — depending on the size and absorptivity of the sample — and imposes few restrictions. E. R. Generazio, "The Role of the Reflection Coefficient in Precision Measurement of Ultrasonic Attenuation," pp. , Materials Evaluat July J. A. Brunk, C. J. Valenza and M. C. Bhardwaj, "Applications and Advantages of Dry Coupling Ultrasonic Tansducers for Materials Characterization and Inspection," pp.

    Measurement Techniques Normal Beam Inspection Pulse‐echo ultrasonic measurements can determine the location of a discontinuity in a part or structure by accurately measuring the time required for a short ultrasonic pulse generated by a transducer to travel through a thickness of material, reflect from the back or the surface of a. E.R. Generazio, "The Role of the Reflection Coefficient in Precision Measurements of Ultrasonic Attenuation", Materials Evaluation, vol. 43, No. 8, , pp. W. Sachse & Y.H. Pao, "On the Determination of Phase and Group Velocities of Disperse.

    Scattering is the reflection of the sound in directions other than its original direction of propagation. Absorption is the conversion of the sound energy to other forms of energy. The combined effect of scattering and absorption is called attenuation. Ultrasonic attenuation is the decay rate of the wave as it propagates through material. Ultrasonic technique of imaging serves an increasingly important role in medical diagnostics. In most of applications, echographic methods are used (ultrasonography, ultrasonic microscopy). Using such methods, an image presenting changes of a reflection coefficient in the interior of analysed structure is being constructed. This chapter presents.


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The role of the reflection coefficient in precision measurement of ultrasonic attenuation Download PDF EPUB FB2

The role of the reflection coefficient in precision measurement of ultrasonic attenuation. By E. Generazio. Abstract. Ultrasonic attenuation measurements using contact, pulse-echo techniques are sensitive to surface roughness and couplant thickness variations.

This can reduce considerable inaccuracies in the measurement of the attenuation Author: E. Generazio. The role of the reflection coefficient in precision measurement of ultrasonic attenuation Ultrasonic attenuation measurements using contact, pulse-echo techniques are sensitive to surface roughness and couplant thickness variations.

This can reduce considerable inaccuracies in the measurement of the attenuation coefficient for broadband pulses. The measurements were carried out using the substitution method based on the pulse-echo technique.

The block diagram for the experimental set-up is depicted in Fig. ultrasonic pulser/receiver plug-in card, model SR (Matec, Hopkinton, MA, USA), was plugged into the microcomputer (PC-AT DX4, clock of MHz and 24 megabytes of RAM) and used to excite the US Cited by: attenuation in the air in [dB/(mHz)], and d0 is the near field of the ultrasonic transducer.

The attenuation in the air a is a function of environmental conditions such as air temperature Tc, air humidity R h, and absolute atmospheric pressure a = f(Tc, R h, P0).Author: Krzysztof Herman, Tadeusz Gudra, Krzysztof Opieliński, Dariusz Banasiak, Tomasz Budzik, Nathalie Ris.

This research investigates the influence of partial reflection on the measurement of the absolute ultrasonic attenuation coefficient using contact transducers.

The partial, frequency-dependent reflection arises from the thin fluid-layer interface formed between the transducer and specimen by: Correction for partial reflection in ultrasonic attenuation measurements using contact transducers Article (PDF Available) in The Journal of the Acoustical Society of America (5) Generazio, E.R., “The Role of the Reflection Coefficient in Precision Measurement of Ultrasonic Attenuation,” Mat.

Eval. 43, (). Google Scholar. In this paper, a method for estimating snow pressure reflection coefficient based on non-contact ultrasound examination is described. A constant frequency and air-coupled ultrasound pulses were used in this study, which incorporates a parametric method for reflected energy estimation.

The experimental part was carried out in situ in the Antarctic, where the snow parameters were measured along. E.R. Generazio, The Role of the Reflection Coefficient in Precision Measurement of Ultrasonic Attenuation, NASA Technical MemorandumAnnual Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California, July 8–13, Imaging Subtle Microstructural Variations in Ceramics with Precision Ultrasonic Velocity and Attenuation Measurements.

Authors; Authors and affiliations; “The Role of the Reflection Coefficient in Precision Measurement of Ultrasonic Attenuation,” Mater. Eval. 43, ().

Get this from a library. The role of the reflection coefficient in precision measurement of ultrasonic attenuation. [Edward R Generazio; Lewis Research Center.]. In this work, the measurement of R (θ) is made using the apparatus shown in Fig. 1(a).It requires accurate positioning of two ultrasonic transducers, each rotated at an angle θ relative to the surface normal of the material sample.

The transducers must maintain the same separation distance through the entire angular range and the axis of rotation of the transducers must lie on the top.

Acoustic properties, speed of sound (SOS), reflection coefficient (R), frequency dependent reflection coefficient, integrated reflection coefficient (IRC), ultrasonic roughness index (URI. ultrasonic reflection coefficient to measure differences in surface roughness. The standard "The Role of the Reflection Coefficient in Precision Measurement of Ultrasonic Attenuation," Mat.

Evai. 43, (). Nagy, P. B., 1. Rose, "Surface Roughness and the Ultrasonic Detection of. In this paper, we present direct narrowband substitution measurement values of the variation in the ultrasonic attenuation coefficient in ex vivo human uterine and cervical tissue, in the 5–10 MHz frequency range.

At 5 MHz, the attenuation coefficient values are similar for the different orientations of uterine tissue with values of – 4. The smooth approximating function found using the proposed approach is shown by the dashed line. The frequency dependent attenuation function of ultrasonic waves in PVDF plastic material is presented in Fig The coefficients a 0 and n determined at the frequency.

comparison of various methods for the measurement of reflection coefficient and ultrasonic attenuation Users without a subscription are not able to see the full content. Please, subscribe or login to access all content. attenuation coefficient α as The absorption coefficient of a material is generally dependent on frequency f, and a good model for this dependency is The rough approximation that b = 1 is often used A(z)=A0e!µAz!=20log10(e)"µA#µA!=afb Attenuation of ultrasound waves in tissue Assuming b~1 A(z,f)=A0e!afz/ Note that the reflection and transmission coefficients are often expressed in decibels (dB) to allow for large changes in signal strength to be more easily compared.

To convert the intensity or power of the wave to dB units, take the log of the reflection or transmission coefficient. THEORY AND APPLICATION OF PRECISION ULTRASONIC THICKNESS GAGING by By thereby restricting measurement range. Sound Attenuation or Absorption --In many organic materials such as low density plastics and rubber, sound energy is attenuated very rapidly at the frequencies used for ultrasonic gaging.

This attenuation typically increases with. It is the result of energy absorption of tissue, as well as reflection and scattering that occurs between the boundaries of tissue with different densities. The attenuation coefficient of tissues is the relation of attenuation to distance, and depends on the tissues traversed and the frequency of the ultrasound wave.

The work presents a new method that tracks the total attenuation of the ultrasonic waves in a mortar during hydration. The method is based on a representation in the complex plane of reflection coefficient of waves backscattered by the mortar layer which takes the form of a circle in the vicinity of a resonance.

Monitoring the diameter of the circle during all stages of hydration shows its.Measure the lengths of the three cylinders with the calliper. 2. Determine the amplitudes and times of flight of the ultrasonic transmission pulses for the threy- e c linders and the two (or three) ultrasonic probes.

3. Calculate the attenuation and sound velocity values. Set-up and procedure - Set the experiment up as shown in Fig. 1.