Ultrasound transmission attenuation tomography using energy-scaled amplitude ratios

2016 ◽  
Author(s):  
Ting Chen ◽  
Junseob Shin ◽  
Lianjie Huang
Keyword(s):  
Amplitude Ratios ◽  
Transmission Attenuation

Propagation and Reflection of Plane Waves in a Rotating Magneto-Elastic Fibre-Reinforced Semi Space with Surface Stress

2020 ◽  
Vol 22 (4) ◽  
pp. 939-958
Author(s):  
Indrajit Roy ◽  
D. P. Acharya ◽  
Sourav Acharya
Keyword(s):  
Surface Stress ◽  
Incident Angle ◽  
Plane Waves ◽  
Three Dimensional ◽  
Elastic Fibre ◽  
Amplitude Ratios ◽  
Governing Equations ◽  
Rotation Surface ◽  
Wave Velocities ◽  
Magnetic Field Rotation

AbstractThe present paper investigates the propagation of quasi longitudinal (qLD) and quasi transverse (qTD) waves in a magneto elastic fibre-reinforced rotating semi-infinite medium. Reflections of waves from the flat boundary with surface stress have been studied in details. The governing equations have been used to obtain the polynomial characteristic equation from which qLD and qTD wave velocities are found. It is observed that both the wave velocities depend upon the incident angle. After imposing the appropriate boundary conditions including surface stress the resultant amplitude ratios for the total displacements have been obtained. Numerically simulated results have been depicted graphically by displaying two and three dimensional graphs to highlight the influence of magnetic field, rotation, surface stress and fibre-reinforcing nature of the material medium on the propagation and reflection of plane waves.

Universal critical amplitude ratios inCHF3

1989 ◽  
Vol 39 (13) ◽  
pp. 9330-9335 ◽  
Author(s):  
Ulrike Närger ◽  
David A. Balzarini
Keyword(s):  
Amplitude Ratios ◽  
Critical Amplitude

scholarly journals Rapid Deconvolution of Low-Resolution Time-of-Flight Data using Bayesian Inference

2019 ◽  
Author(s):  
Cornelius Pieterse ◽  
Michiel B. De Kock ◽  
Wesley D. Robertson ◽  
Hans C. Eggers ◽  
R. J. Dwayne Miller
Keyword(s):  
Time Of Flight ◽  
Stopping Criterion ◽  
Amplitude Ratios ◽  
Resolution Time ◽  
Low Resolution ◽  
Flight Data ◽  
Additional Information ◽  
Bayesian Prior ◽  
Accurate Quantification ◽  
General Method

Deconvolution of low-resolution time-of-flight data has numerous advantages including the ability to extract additional information from the experimental data. We augment the well-known Lucy-Richardson deconvolution algorithm by various Bayesian prior distributions and show that a prior of second-differences of the signal outperforms the standard Lucy-Richardson algorithm, accelerating the rate of convergence by more than a factor of four, while preserving the peak amplitude ratios of a similar fraction of the total peaks. A novel stopping criterion and boosting mechanism is implemented to ensure these methods converge to a similar entropy, and that local minima are avoided, respectively. Improvement by a factor of two in mass resolution allows more accurate quantification of the spectra. The general method is demonstrated in this paper by the deconvolution of fragmentation peaks of the DHB matrix, as well as the BTP thermometer ion, following femtosecond ultraviolet laser desorption.

Estimating amplitude ratios in boundary layer stability theory: a comparison between two approaches

2001 ◽  
Vol 439 ◽  
pp. 403-412 ◽  
Author(s):  
RAMA GOVINDARAJAN ◽  
R. NARASIMHA
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Small Difference ◽  
Detailed Comparison ◽  
The Other ◽  
Boundary Layer Stability ◽  
Mean Flow ◽  
Amplitude Ratios ◽  
The Stability ◽  
Local Reynolds Number

We first demonstrate that, if the contributions of higher-order mean flow are ignored, the parabolized stability equations (Bertolotti et al. 1992) and the ‘full’ non-parallel equation of Govindarajan & Narasimha (1995, hereafter GN95) are both equivalent to order R−1 in the local Reynolds number R to Gaster's (1974) equation for the stability of spatially developing boundary layers. It is therefore of some concern that a detailed comparison between Gaster (1974) and GN95 reveals a small difference in the computed amplitude ratios. Although this difference is not significant in practical terms in Blasius flow, it is traced here to the approximation, in Gaster's method, of neglecting the change in eigenfunction shape due to flow non-parallelism. This approximation is not justified in the critical and the wall layers, where the neglected term is respectively O(R−2/3) and O(R−1) compared to the largest term. The excellent agreement of GN95 with exact numerical simulations, on the other hand, suggests that the effect of change in eigenfunction is accurately taken into account in that paper.

PcP from the nuclear explosion BILBY September 13, 1963

1965 ◽  
Vol 55 (2) ◽  
pp. 441-461
Author(s):  
Goetz G. R. Buchbinder
Keyword(s):  
Standard Deviation ◽  
Seismic Velocity ◽  
Nuclear Explosion ◽  
Amplitude Ratios ◽  
The Core ◽  
Core Boundary

Abstract The core-reflected phase, PcP, from the BILBY event, received at stations between 19° and 88°, arrived early by an average of 1.80 seconds with respect to the Jeffries-Bullen tables. The standard deviation of these data was 0.77 seconds. The corresponding P phases were early by 1.34 seconds. The tables therefore need adjustments. If the core boundary is to be moved by more than 10 km from the value of 2898 km then the mantle seismic velocity immediately above the core must be changed also. The PcP/P amplitude ratios are nearly always much larger than those predicted theoretically.

Radial Velocities for the Pulsating Subdwarf B Star PG 1605+072

2002 ◽  
Vol 185 ◽  
pp. 376-377
Author(s):  
V.M. Woolf ◽  
C.S. Jeffery ◽  
D.L. Pollacco
Keyword(s):  
Radial Velocity ◽  
Line Shape ◽  
High Speed ◽  
Radial Velocities ◽  
Peak Amplitude ◽  
Amplitude Ratios ◽  
Time Line ◽  
Photometric Observations ◽  
Velocity Variations ◽  
Over Time

AbstractWe have performed high-speed spectroscopy of the pulsating subdwarf B star PG 1605+072. Its radial velocity variations have frequencies similar to those reported from photometric observations. Peak amplitude ratios are different, probably as a result of power shifting between modes over time. Line-shape variations have also been detected.

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