scholarly journals Photoacoustic–ultrasonic dual-mode microscopy with local speed-of-sound estimation

2020 ◽  
Vol 45 (14) ◽  
pp. 3840
Author(s):  
Wentian Chen ◽  
Chao Tao ◽  
Nghia Q. Nguyen ◽  
Richard W. Prager ◽  
Xiaojun Liu
Keyword(s):  
Speed Of Sound ◽  
Dual Mode ◽  
Local Speed

The diffraction of blast. II

1950 ◽  
Vol 200 (1063) ◽  
pp. 554-565 ◽  
Keyword(s):  
Solid Surface ◽  
Speed Of Sound ◽  
Uniform Flow ◽  
Incident Shock ◽  
Plane Shock ◽  
Angle Of Incidence ◽  
Straight Segment ◽  
Reflected Shock ◽  
Perpendicular Distance ◽  
Local Speed

The head-on encounter of a plane shock, of any strength, with a solid corner of angle π - δ is investigated mathematically, when δ is small, by a method similar to that of part I. The incident shock is found to be reflected from each face as a straight segment, the two segments being joined by a shorter curved portion. Behind each straight segment is a region of uniform flow, the two regions being joined by one of non-uniform flow, bounded by arcs of a circle with centre at the corner, which expands at the local speed of sound, and by the shock, which is curved only where intersected by the said circle. The pressure is approximately equal in the two regions of uniform flow, but is less in the region of non-uniform flow between them; and it is found that if the deficiency of pressure therein, divided by the angle δ and by the excess of pressure behind the reflected shock over that of the atmosphere, be plotted at points along the solid surface, after the incident shock has travelled a given perpendicular distance beyond the corner, then the curve is independent of δ and of the precise angle of incidence of the shock, and changes remarkably little in the whole range of incident shock strengths from 0 to ∞ (see figures 5 to 8). It is suggested that some of the above qualitative conclusions may be true even if δ is not small. The case δ<0, when the corner is concave to the atmosphere, is also considered. Shock patterns are found in cases when the incident shock has already been reflected from one, or both, walls before reaching the corner (figures 9 to 11).

Influence of Internal Wave on the Sound Propagation in the Subsurface Bubble Layer

2011 ◽  
Vol 8 (1) ◽  
pp. 54-64
Author(s):  
R. Grimshaw ◽  
L.A. Ostrovsky ◽  
A.S. Topolnikov ◽  
K.R. Khusnutdinova
Keyword(s):  
Internal Wave ◽  
Speed Of Sound ◽  
Acoustic Signal ◽  
Sound Propagation ◽  
Japan Sea ◽  
Subsurface Ocean ◽  
Ocean Layer ◽  
Bubble Layer ◽  
Linear Internal Wave ◽  
Local Speed

In the paper the influence of non-linear internal wave on the propagation of acoustic signal in the subsurface ocean layer containing gas bubbles is considered. During interaction with surface waves the internal wave causes its collapse and influences the structure of bubble layer. Inhomogeneous structure of the layer promotes the local speed of sound and intensity of scattering near the ocean surface to modulate by internal wave with slight shift in phase in the direction of its propagation, which agree with recent experimental observations made on the shelf of Japan Sea.

Note on instability of compressible jets and wakes to long-wave disturbances

1965 ◽  
Vol 22 (2) ◽  
pp. 415-415 ◽  
Author(s):  
A. E. Gill ◽  
P. G. Drazin
Keyword(s):  
Speed Of Sound ◽  
Frame Of Reference ◽  
Two Dimensional ◽  
Perfect Gas ◽  
Wave Disturbances ◽  
Long Wave ◽  
Local Speed

A two-dimensional jet or wake is observed in a frame of reference moving with the fluid at infinity, so that the velocity w(y) in the x-direction tends to zero as y → ± ∞. The fluid is assumed to be an inviscid perfect gas, to undergo-adiabatic changes, and the local speed of sound to be a function of y such that a(y)→ a∞, as y → ±∞. If the disturbance pressure has the form

scholarly journals Local speed of sound estimation in tissue using pulse-echo ultrasound: Model-based approach

2018 ◽  
Vol 144 (1) ◽  
pp. 254-266 ◽  
Author(s):  
Marko Jakovljevic ◽  
Scott Hsieh ◽  
Rehman Ali ◽  
Gustavo Chau Loo Kung ◽  
Dongwoon Hyun ◽  
...  
Keyword(s):  
Speed Of Sound ◽  
Model Based ◽  
Pulse Echo ◽  
Local Speed

scholarly journals Accumulation of a Rapidly Rotating Protostar and the Formation of an Associated Nebula as a Result of Angular Momentum Transport by Turbulent Friction

1981 ◽  
Vol 93 ◽  
pp. 105-106
Author(s):  
W. M. Tscharnuter
Keyword(s):  
Angular Momentum ◽  
Speed Of Sound ◽  
Momentum Transport ◽  
Length Scale ◽  
Turbulent Friction ◽  
Angular Momentum Transport ◽  
Viscosity Parameter ◽  
Efficiency Parameter ◽  
Typical Length ◽  
Local Speed

The influence of angular momentum transport by turbulent friction on the structure of a rotating protostar has been investigated. Turbulence is characterized by a simple viscosity parameter η = ξ·cs·1, where cs denotes the local speed of sound, 1 the typical length scale of the largest eddies (thickness of the nebula) and ξ the “efficiency” parameter (= 1/10 in our model).

Noninvasive estimation of local speed of sound by pulse-echo ultrasound in a rat model of nonalcoholic fatty liver

2021 ◽  
Author(s):  
Arsenii V Telichko ◽  
Rehman Ali ◽  
Thurston Brevett ◽  
Huaijun Wang ◽  
Jose Vilches-Moure ◽  
...  
Keyword(s):  
Fatty Liver ◽  
Rat Model ◽  
Speed Of Sound ◽  
Ground Truth ◽  
Zucker Rats ◽  
Alcoholic Fatty Liver ◽  
Average Speed ◽  
Global Average ◽  
Hepatic Fat ◽  
Local Speed

Abstract Objective: Speed of sound has previously been demonstrated to correlate with fat concentration in the liver. However, estimating speed of sound in the liver noninvasively can be biased by the speed of sound of the tissue layers overlying the liver. Here, we demonstrate a noninvasive local speed of sound estimator, which is based on a layered media assumption, that can accurately capture the speed of sound in the liver. We validate the estimator using an obese Zucker rat model of non-alcoholic fatty liver disease and correlate the local speed of sound with liver steatosis. Approach: We estimated the local and global average speed of sound noninvasively in 4 lean Zucker rats fed a normal diet and 16 obese Zucker rats fed a high fat diet for up to 8 weeks. The ground truth speed of sound and fat concentration were measured from the excised liver using established techniques. Main Results: The noninvasive, local speed of sound estimates of the livers were similar in value to their corresponding "ground truth'' measurements, having a slope ± standard error of the regression of 0.82 ± 0.15 (R2 = 0.74 and p < 0.001). Measurement of the noninvasive global average speed of sound did not reliably capture the ``ground truth'' speed of sound in the liver, having a slope of 0.35 ± 0.07 (R2 = 0.74 and p < 0.001). Decreasing local speed of sound was observed with increasing hepatic fat accumulation (approximately -1.7 m/s per 1% increase in hepatic fat) and histopathology steatosis grading (approximately -10 to -13 m/s per unit increase in steatosis grade). Local speed of sound estimates were highly correlated with steatosis grade, having Pearson and Spearman correlation coefficients both ranging from -0.87 to -0.78. In addition, a lobe-dependent speed of sound in the liver was observed by the ex vivo measurements, with speed of sound differences of up to 25 m/s (p < 0.003) observed between lobes in the liver of the same animal. Significance: The findings of this study suggest that local speed of sound estimation has the potential to be used to predict or assist in the measurement of hepatic fat concentration and that the global average speed of sound should be avoided in hepatic fat estimation due to significant bias in the speed of sound estimate.

Sign in / Sign up

Export Citation Format

Share Document