scholarly journals Diffusive subsurface Rayleigh mode induced by embedded ultrasonic waveguide

2020 ◽  
Author(s):  
Yishi Lee ◽  
Wayne Hall ◽  
R. Daniel Seale ◽  
Christopher A. Senalik
Keyword(s):  
Rayleigh Mode ◽  
Ultrasonic Waveguide

Attenuation of Rayleigh-wave amplitudes across Eurasia

1977 ◽  
Vol 67 (3) ◽  
pp. 751-769
Author(s):  
Nazieh K. Yacoub ◽  
Brian J. Mitchell
Keyword(s):  
Rayleigh Wave ◽  
Regional Variation ◽  
Wave Amplitude ◽  
Period Range ◽  
Attenuation Coefficients ◽  
Nuclear Explosions ◽  
Amplitude Data ◽  
Standard Deviations ◽  
Data Yield ◽  
Rayleigh Mode

abstract Surface waves generated by six earthquakes and two nuclear explosions are used to study the attenuation coefficients of the fundamental Rayleigh mode across Eurasia. Rayleigh-wave amplitude data yield average attenuation coefficients at periods between 4 and 50 sec. The data exhibit relatively large standard deviations and in some cases the average attenuation coefficients take on negative values which may be due to regional variations of the attenuative properties of the crust, lateral refraction, multipathing and scattering. A method has been developed to investigate the regional variation in the attenuative properties of the Eurasian crust and its effect on surface-wave amplitude data, employing the evaluated average attenuation coefficients for the fundamental Rayleigh mode. For this investigation, Eurasia is divided into two regions, one considered to be relatively stable, and the other considered to be tectonic in nature. This regionalization shows that the tectonic regions exhibit higher attenuation than the stable regions in the period range below about 20 sec, whereas in the period range above about 20 sec, no clear difference can be observed for the two regions. Although the effects of lateral refraction and multipathing may still significantly affect the observations, the regionalization lowers the standard deviations considerably and eliminates the negative values which were obtained in the unregionalized determinations.

scholarly journals In-Situ Process and Simulation of High-Performance Piezoelectric-on-Silicon Substrate for SAW Sensor

2021 ◽  
Vol 8 ◽  
Author(s):  
Rui Ma ◽  
Weiguo Liu ◽  
Xueping Sun ◽  
Shun Zhou
Keyword(s):  
Thin Film ◽  
Lithium Niobate ◽  
High Performance ◽  
Electromechanical Coupling ◽  
Substrate Material ◽  
Electromechanical Coupling Coefficient ◽  
Bonding Layer ◽  
Saw Sensor ◽  
Rayleigh Mode

This paper studied the manufacturing process of Piezoelectric-on-Silicon (POS) substrate which integrates 128° Y–X Lithium niobate thin film and silicon wafer using Smart-Cut technology. The blistering and exfoliation processes of the He as-implanted LN crystal under different annealing temperatures are observed by the in-situ method. Unlike the conventional polishing process, the stripping mechanism of the Lithium niobate thin film is changed by controlling annealing temperature, which can improve the surface morphology of the peeling lithium niobate thin film. We prepared the 128° Y–X POS substrate with high single-crystal Lithium niobate thin film and surface roughness of 3.91 nm through Benzocyclobutene bonding. After simulating the surface acoustic wave (SAW) characteristics of the POS substrate, the results demonstrate that the Benzocyclobutene layer not only performs as a bonding layer but also can couple more vibrations into the LN thin film. The electromechanical coupling coefficient of the POS substrate is up to 7.59% in the Rayleigh mode when hLN/λ is 0.3 and hBCB/λ is 0.1. Therefore, as a high-performance substrate material, the POS substrate has proved to be an efficient method to miniaturize and integrate the SAW sensor.

Observations from some gnome seismograms

1962 ◽  
Vol 52 (5) ◽  
pp. 1075-1077
Author(s):  
Dorris M. Hankins
Keyword(s):  
Surface Layer ◽  
Seismic Signals ◽  
Rayleigh Mode

abstract Comparison of gnome seismic signals at four stations with seismograms from an explosion in tuff show relatively more energy in the Pg phase than would be predicted from first phase amplitudes. Dispression curve for a surface layer Rayleigh mode is given.

Measurement of acoustic properties of near‐surface soils using an ultrasonic waveguide

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 460-465 ◽  
Author(s):  
Rob Long ◽  
Thomas Vogt ◽  
Mike Lowe ◽  
Peter Cawley
Keyword(s):  
Urban Areas ◽  
Surrounding Medium ◽  
Longitudinal Mode ◽  
Acoustic Properties ◽  
P Wave ◽  
S Wave ◽  
Surface Soils ◽  
Near Surface ◽  
Experimental Laboratory ◽  
Ultrasonic Waveguide

A technique is presented that uses a circular ultrasonic waveguide to measure the bulk shear (S‐wave) and longitudinal (P‐wave) velocities of unconsolidated media, with particular application to near‐surface soils. The technique requires measuring the attenuation characteristics of the fundamental longitudinal mode that propagates along an embedded bar, from which the acoustic properties of the surrounding medium are inferred. The principles behind the technique are discussed, and the results of an experimental laboratory validation are presented, followed by details of in‐situ soil property measurements obtained at various sites in urban areas of the United Kingdom.

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