High Frequency Ultrasonic Measurements

1988 ◽  
Vol 21 (5) ◽  
pp. 133-136
Author(s):  
N Zarsav
Keyword(s):  
High Frequency ◽  
Polymer Coating ◽  
Steel Sheet ◽  
Lamb Waves ◽  
Thin Plates ◽  
Design Features ◽  
Degree Of Cure ◽  
Double Probe ◽  
Ultrasonic Measurements

The use of high frequency ultrasonic Lamb waves to measure the thickness of thin plates and foils, is discussed and the feasibility of their application to the determination of the degree of cure of polymer coating on coated tin plated steel sheet (as used by the food can industry) is evaluated. The paper also discusses briefly the design features of the purpose built precision double probe ultrasonic goniometer used to carry out these measurements.

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

Scattering of High-Frequency Flexural Oscillations in Thin Plates

1999 ◽  
Vol 4 (4) ◽  
pp. 461-479 ◽  
Author(s):  
Gavin R. Thomson ◽  
Christian Constanda
Keyword(s):  
High Frequency ◽  
Thin Plates

Very Early and Simple Determination of Chorionic and Amniotic Type in Twin Gestations by High-Frequency Transvaginal Ultrasonography

1997 ◽  
Vol 46 (3) ◽  
pp. 167-173 ◽  
Author(s):  
W. Malinowski
Keyword(s):  
Study Design ◽  
High Frequency ◽  
Twin Pregnancy ◽  
Rapid Determination ◽  
Early Stage ◽  
Transvaginal Ultrasonography ◽  
Pathologic Evaluation ◽  
Twin Pregnancies

AbstractObjective. The aim was to determine the chorionic and amniotic types in multifetal pregnancies with transvaginal ultrasonography at very early stage of gestation.Study design. Twenty-one spontaneous multifetal pregnancies were scanned transvaginally before 8 weeks' gestation (four of them from 4th week). The chorionic and amniotic type was determined ultrasonographically. All twin gestations had postpartum pathologic evaluation of the placenta and histologic determination of the chorionic and amniotic type.Results. Ultrasonographic evaluation of the 21 pregnancies demonstrated 20 twin and 1 triplet gestation. Four of the twin pregnancies were monochorionic-diamniotic. Triplet was monochorionic-triamniotic (spontaneously aborted in 8th week of gestation). In all 20 twin pregnancies, transvaginal ultrasonography correctly predicted the chorionic and amniotic type before 8 weeks of gestation.Conclusion. Transvaginal ultrasonography allows a reliable, simple and rapid determination; the dichorionic twin pregnancy in 4 weeks, monochorionic in 5 weeks, and differentiation of mono-or diamniotic in 7 weeks of gestation.

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