Plastic Waves of Combined Stresses Due to Longitudinal Impact of a Pretorqued Tube—Part 1: Experimental Results

1970 ◽  
Vol 37 (4) ◽  
pp. 1107-1112 ◽  
Author(s):  
J. Lipkin ◽  
R. J. Clifton
Keyword(s):  
Slow Wave ◽  
Longitudinal Strain ◽  
Fast Wave ◽  
Longitudinal Impact ◽  
Strain Response ◽  
Torsional Strain ◽  
Time Profiles ◽  
Combined Stresses ◽  
Fast Waves ◽  
Longitudinal Strains

Experiments are reported in which annealed aluminum tubes are subjected to a static plastic torque followed by a longitudinal compressive impact. Measurements are made of both longitudinal and shear strain-time profiles at stations along the specimen. Qualitatively, the strain response at the gages corresponds to the arrival of a fast wave for which torsional strain decreases while longitudinal strain increases followed by a slow wave for which both torsional and longitudinal strains increase. Between the slow and fast waves and following the slow wave, a strain rate of the order of 10 sec−1 is maintained.

Pulse Propagation in Straight Circular Elastic Tubes

1972 ◽  
Vol 39 (4) ◽  
pp. 1011-1018 ◽  
Author(s):  
W. Goldsmith ◽  
P. Y. Lee ◽  
J. L. Sackman
Keyword(s):  
Experimental Investigation ◽  
Pulse Duration ◽  
Longitudinal Strain ◽  
Pulse Propagation ◽  
Transverse Strain ◽  
Longitudinal Impact ◽  
Elastic Tubes ◽  
Air Gun ◽  
Steel Balls ◽  
Longitudinal Strains

An experimental investigation of elastic waves produced by the longitudinal impact of strikers with straight 2024 aluminum tubes of 1-in. dia and wall thicknesses of 0.035 in. (thin-walled), 0.095 in. (medium thick-walled), and 0.5 in. (solid bar) was performed by means of the Hopkinson bar technique. For most of the tests the strikers consisted of 1/2-in-dia steel balls; however, 1/4-in-dia, 3/16-in-dia and 1/8-in-dia steel balls were also used to permit variation in pulse duration. Both central and eccentric impact were achieved by firing the striker from an air gun at a predetermined pressure against the carefully positioned target; the initial velocity of the striker was measured whenever necessary. Longitudinal strain records of the resulting pulse from positions both on the inside and outside surfaces of the hollow specimens and on the outside of the solid bar were obtained by using strain gages of either foil or semiconductor type; some transverse strain histories were also measured concurrently. The transient longitudinal strains were predicted theoretically by solving the one-dimensional Rayleigh-Love equation of wave propagation in a semi-infinite tube with the aid of a computer program. The input to the program consisted of the measured strain record at the first gage station. Reasonable agreement between the data and the results of these calculations was obtained. An experimental investigation of the effect of shortening the pulse duration, the relation between the transverse and longitudinal strain at the same position, and the nature of the antisymmetrical component in the eccentric shots was also undertaken.

scholarly journals P6476Multi-layer and segmental longitudinal strain response to incremental cycle exercise

2018 ◽  
Vol 39 (suppl_1) ◽  
Author(s):  
M Stout ◽  
G McDowell ◽  
K Pearce ◽  
H Garnett
Keyword(s):  
Longitudinal Strain ◽  
Strain Response ◽  
Cycle Exercise

La S-adénosyl-L-homocystéine : 1. Inductrice de sommeil

1980 ◽  
Vol 58 (2) ◽  
pp. 160-166 ◽  
Author(s):  
Pierre Fonlupt ◽  
Maurice Roche ◽  
Lucien Cronenberger ◽  
Henri Pacheco
Keyword(s):  
Slow Wave ◽  
Fast Wave ◽  
Serotonin Metabolism ◽  
Sleep Patterns

S-Adenosylhomocysteine, 0.1–20 mg/kg, influences the sleep patterns of rat, cat and rabbit by increasing the slow-wave and fast-wave sleep for 6 h. The SAH effects are increased by p-chlorophenylalanine and iproniazid and unchanged by reserpine. SAH effects are correlated with modification of norepinephrine and serotonin metabolism.

A novel hybrid slow-wave/fast-wave traveling-wave amplifier

1997 ◽  
Vol 25 (5) ◽  
pp. 1150-1154 ◽  
Author(s):  
W. Lawson ◽  
A. Fernandez ◽  
T. Hutchings ◽  
G.P. Saraph
Keyword(s):  
Slow Wave ◽  
Traveling Wave ◽  
Fast Wave ◽  
Traveling Wave Amplifier

scholarly journals Edge plasma parameters affecting fast wave and slow wave intensities in scrape off layer

2020 ◽  
Author(s):  
L. Ai ◽  
L. N. Liu ◽  
C. M. Qin ◽  
X. J. Zhang ◽  
Y. P. Zhao
Keyword(s):  
Slow Wave ◽  
Edge Plasma ◽  
Fast Wave ◽  
Plasma Parameters

Impact of Thoracic Endovascular Aortic Repair on Pulsatile Circumferential and Longitudinal Strain in Patients With Aneurysm

2017 ◽  
Vol 24 (2) ◽  
pp. 281-289 ◽  
Author(s):  
Foeke J. H. Nauta ◽  
Guido H. W. van Bogerijen ◽  
Chiara Trentin ◽  
Michele Conti ◽  
Ferdinando Auricchio ◽  
...  
Keyword(s):  
Longitudinal Strain ◽  
Celiac Trunk ◽  
Ascending Aorta ◽  
Thoracic Endovascular Aortic Repair ◽  
Endovascular Aortic Repair ◽  
Sinotubular Junction ◽  
Aortic Repair ◽  
Brachiocephalic Trunk ◽  
The Impact ◽  
Longitudinal Strains

Purpose: To quantify both pulsatile longitudinal and circumferential aortic strains before and after thoracic endovascular aortic repair (TEVAR), potentially clarifying TEVAR-related complications. Methods: This retrospective study assessed the impact of TEVAR on pulsatile aortic strains through custom developed software and cardiac-gated computed tomography imaging of 8 thoracic aneurysm patients (mean age 71.0±8.2 years; 6 men) performed before TEVAR and during follow-up (median 0.1 months, interquartile range 0.1–5.8). Lengths of the ascending aorta, the aortic arch, and the descending aorta were measured. Diameters and areas were computed at the sinotubular junction, brachiocephalic trunk, left subclavian artery, and the celiac trunk. Pulsatile longitudinal and circumferential strains were quantified as systolic increments of length and circumference divided by the corresponding diastolic values. Results: Average pulsatile longitudinal strain ranged from 1.4% to 7.1%, was highest in the arch (p<0.001), and increased after TEVAR by 77% in the arch (7.1%±2.5% vs 12.5%±5.1%, p=0.04) and by 69% in the ascending aorta (5.6±2.3% vs 9.4±4.4%, p=0.06). Average pulsatile circumferential strain ranged from 3.6% to 5.0% before TEVAR and did not differ significantly throughout the thoracic aorta; there was a nonsignificant increase after TEVAR at the unstented sinotubular junction (5.0%±1.4% vs 6.3%±1.0%, p=0.18), with a significant increase at the celiac trunk (3.6%±1.8% vs 6.2%±1.8%, p=0.02). Pulsatile circumferential strains within stented segments were deemed unreliable due to image artifacts. Conclusion: TEVAR was associated with an increase of pulsatile longitudinal strains (in the arch) and circumferential strains (at the celiac trunk) in unstented aortic segments. These observations suggest increased pulsatile wall stress after TEVAR in segments adjacent to the device, which may contribute to the understanding of stent-graft–related complications such as retrograde dissection, aneurysm formation, and rupture.

IMEX peer methods for fast-wave–slow-wave problems

2017 ◽  
Vol 118 ◽  
pp. 221-237 ◽  
Author(s):  
Behnam Soleimani ◽  
Oswald Knoth ◽  
Rüdiger Weiner
Keyword(s):  
Slow Wave ◽  
Fast Wave ◽  
Wave Problems

scholarly journals Left and right ventricular longitudinal strains are associated with poor outcome in COVID-19: a systematic review and meta-analysis

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Arief Wibowo ◽  
Raymond Pranata ◽  
Astri Astuti ◽  
Badai Bhatara Tiksnadi ◽  
Erwan Martanto ◽  
...  
Keyword(s):  
Systematic Review ◽  
Longitudinal Strain ◽  
Meta Analysis ◽  
Global Longitudinal Strain ◽  
Left Ventricular ◽  
Poor Outcome ◽  
Literature Searches ◽  
Increased Risk ◽  
Left And Right ◽  
Longitudinal Strains

Abstract Background This systematic review and meta-analysis aimed to assess whether ventricular longitudinal strain can be used as a prognostication tool in patients with coronavirus disease 2019 (COVID-19). Methods Systematic literature searches of PubMed, Embase, and EuropePMC databases were performed on 16 November 2020. Left ventricular global longitudinal strain (LV-GLS) refers to LV contraction measurement using the speckle tracking-based method refers to the mean of strain values of the RV free wall (three segments) measured using echocardiography. The main outcome was poor outcome, defined as a composite of mortality and severe COVID-19. Results Seven studies comprising of 612 patients were included in meta-analysis. Six studies have mortality as their outcome, and 1 study has severity as their outcome. Patients with poor outcome have lower LV-GLS (SMD 1.15 (0.57, 1.72), p < 0.001; I2 70.4%). Each 1% decrease in LV-GLS was associated with 1.4x increased risk of poor outcome (OR 1.37 (1.12, 1.67), p = 0.002; I2 48.8%). Patients with poor outcome have lower RV-LS (SMD 1.18 (0.91, 1.45), p < 0.001; I2 0%). Each 1% decrease in RV-LS was associated with 1.3x increased risk of poor outcome (OR 1.25 (1.15, 1.35), p < 0.001; I2 11.8%). Subgroup analysis showed that for every 1% decrease in LV-GLS and RV-LS is increased mortality with OR of 1.30 (1.12, 1.50) and OR of 1.24 (1.14, 1.35), respectively. Conclusion This study shows that lower LV-GLS and RV-LS measurements were associated with poor outcome in patients with COVID-19. Trial registration PROSPERO CRD42020221144

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