Development of a new algorithm for accurate estimation of GPR's wave propagation velocity by common-offset survey method

2016 ◽  
Vol 83 ◽  
pp. 104-113 ◽  
Author(s):  
Janet F.C. Sham ◽  
Wallace W.L. Lai
Keyword(s):  
Wave Propagation ◽  
Propagation Velocity ◽  
Survey Method ◽  
Accurate Estimation ◽  
Wave Propagation Velocity

scholarly journals A coupling model based on grey relational analysis and stepwise discriminant analysis for wood defect area identification by stress wave

BioResources ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 1171-1186
Author(s):  
Xin Li ◽  
Wei Qian ◽  
Liting Cheng ◽  
Lihong Chang
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Propagation Velocity ◽  
Wood Specimen ◽  
Coupling Model ◽  
Stress Wave Propagation ◽  
Sectional Area ◽  
Wave Propagation Velocity ◽  
Cross Sectional ◽  
Stress Wave Propagation Velocity

Based on the experimental idea of reverse simulation, a quantitative area of hole was excavated at the sectional center of a wood specimen. The excavation area was 1/32S, 1/16S, 1/8S, 1/4S, and 1/2S (where S represents cross-sectional area of the complete specimen) and stress wave nondestructive testing of six sensors was performed. The stress wave propagation paths were statistically summarized to obtain the stress wave propagation velocity (Va) for two adjacent sensors, the stress wave propagation velocity (Vb) for two separated sensors, and the stress wave propagation velocity (Vc) for two opposite sensors. Furthermore, by analyzing the advantages and disadvantages of grey relation and stepwise discriminant model when both of them were used alone, a coupling model generated from them was established to dispose the test data. The attenuation ratios Ψa, Ψb, and Ψc of stress wave under three propagation paths and their relation ratios Va/Vb, Vb/Vc, and Va/Vc, a total of six groups of measured data, were selected as discriminant factors for the hole area grade of the wood specimen. The verification results showed that the discriminant accuracy of the coupling model was 100%, and it was concluded that the attenuation ratio (Ψb) of the stress wave propagation velocity for two separated sensors had the strongest discriminant ability against cross-sectional area of the specimen.

scholarly journals Microenvironmental Modulation of Calcium Wave Propagation Velocity in Engineered Cardiac Tissues

2018 ◽  
Vol 11 (5) ◽  
pp. 337-352 ◽  
Author(s):  
Andrew P. Petersen ◽  
Davi M. Lyra-Leite ◽  
Nethika R. Ariyasinghe ◽  
Nathan Cho ◽  
Celeste M. Goodwin ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Propagation Velocity ◽  
Calcium Wave ◽  
Wave Propagation Velocity ◽  
Cardiac Tissues

Developmental changes in flow-wave propagation velocity in embryonic chick vascular system

1997 ◽  
Vol 273 (3) ◽  
pp. H1523-H1529 ◽  
Author(s):  
M. Yoshigi ◽  
J. M. Ettel ◽  
B. B. Keller
Keyword(s):  
Wave Propagation ◽  
Phase Velocity ◽  
Wave Front ◽  
Blood Volume ◽  
Propagation Velocity ◽  
Vascular System ◽  
Front Velocity ◽  
Developmental Changes ◽  
Wave Propagation Velocity ◽  
Circulating Blood Volume

We analyzed flow-wave propagation velocity in the early embryonic vascular system and its responses to acute alterations in circulating blood volume. Two 20-MHz pulsed Doppler velocimeters were positioned along the arterial system in stage 18 (n = 12), 21 (n = 10), and 24 (n = 11) chick embryos. Distance between the two measurement sites was measured by video-microscopy. Phase velocity was calculated using Fourier transform up to the fourth harmonics. Wave-front velocity was also calculated by threshold technique. In a subset of embryos at stage 24 (n = 10), circulating blood volume was acutely altered to change stroke volume. Mean phase velocity increased from 42.9 +/- 3.3 to 95.8 +/- 7.5 cm/s from stage 18 to 24 (P < 0.05 by analysis of variance), whereas wave-front velocity increased from 52.8 +/- 2.4 to 72.2 +/- 5.2 cm/s. Stroke volume and mean aortic pressure paralleled the changes in mean phase velocity and wave-front velocity in normal development and in response to changes in circulating blood volume. Thus developmental changes in wave-propagation velocity were consistent with changes in the size of the vascular system, pressure range, and elastic properties of the arterial wall during systemic vasculogenesis in the embryo.

Postprandial changes in intestinal slow-wave propagation reflect a decrease in cell coupling

1989 ◽  
Vol 257 (3) ◽  
pp. G463-G469
Author(s):  
D. Terasaka ◽  
A. Bortoff ◽  
L. F. Sillin
Keyword(s):  
Wave Propagation ◽  
Electrical Activity ◽  
Slow Wave ◽  
Propagation Velocity ◽  
Maximum Rate ◽  
Internal Resistance ◽  
Cell Coupling ◽  
Wave Propagation Velocity ◽  
Fasting Level ◽  
Amplitude Maximum

The purpose of these studies was to determine the effects of feeding on jejunal slow-wave propagation velocity (SWPV). Nine cats were instrumented with six pairs of electrodes implanted 4 cm apart on the jejunum. Electrical activity was recorded at the end of an 18-h fast after which each animal was fed 60 g of canned cat food. Recordings were continued during feeding and for several hours thereafter. This procedure was repeated at least twice for each cat. Average SWPV (cm/s) decreased from a fasting level of 2.28 +/- 0.20 (mean of means +/- SE) to 1.93 +/- 0.16 at 10-20 min, 1.51 +/- 0.11 at 1 h, and 1.37 +/- 0.10 at 3 h postprandially. Corresponding SW frequencies (SWFs) were 19.6 +/- 0.3, 18.7 +/- 0.2, 19.2 +/- 0.2, and 19.0 +/- 0.2 cycles/min, respectively. The differences between the fasting SWPV and that at 1 and 3 h were significant (P less than 0.05). When SWPV was plotted as a function of SWF, the slopes of the corresponding curves were also found to decrease postprandially (P less than 0.05, fasting vs. 1 and 3 h). There was no apparent change in SW amplitude, maximum rate of SW depolarization, or threshold. In the absence of changes in these parameters, the divergence of the slopes at lower SWFs indicates that the decrease in SWPV is because of increased internal resistance, probably the result of uncoupling of intestinal muscle cells. The change is rapid in onset and long in duration, suggesting that an uncoupling factor is released during ingestion of a meal, and that its effect persists for several hours.

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