scholarly journals On the determination of a global strain rate model

2000 ◽  
Vol 52 (10) ◽  
pp. 765-770 ◽  
Author(s):  
Corné Kreemer ◽  
John Haines ◽  
William E. Holt ◽  
Geoffrey Blewitt ◽  
David Lavallee
Keyword(s):  
Strain Rate ◽  
Rate Model ◽  
Global Strain ◽  
Global Strain Rate

scholarly journals A geodetic plate motion and Global Strain Rate Model

2014 ◽  
Vol 15 (10) ◽  
pp. 3849-3889 ◽  
Author(s):  
Corné Kreemer ◽  
Geoffrey Blewitt ◽  
Elliot C. Klein
Keyword(s):  
Strain Rate ◽  
Plate Motion ◽  
Rate Model ◽  
Global Strain ◽  
Global Strain Rate

Determination of the Heat Release Distribution in Turbulent Flames by a Model Based Correction of OH* Chemiluminescence

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Martin Lauer ◽  
Mathieu Zellhuber ◽  
Thomas Sattelmayer ◽  
Christopher J. Aul
Keyword(s):  
Strain Rate ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Correction Method ◽  
Turbulent Flames ◽  
Lookup Table ◽  
Rate Model ◽  
Model Based

Imaging of OH* or CH* chemiluminescence with intensified cameras is often employed for the determination of heat release in premixed flames. Proportionality is commonly assumed, but in the turbulent case this assumption is not justified. Substantial deviations from proportionality are observed, which are due to turbulence-chemistry interactions. In this study a model based correction method is presented to obtain a better approximation of the spatially resolved heat release rate of lean turbulent flames from OH* measurements. The correction method uses a statistical strain rate model to account for the turbulence influence. The strain rate model is evaluated with time-resolved velocity measurements of the turbulent flow. Additionally, one-dimensional simulations of strained counterflow flames are performed to consider the nonlinear effect of turbulence on chemiluminescence intensities. A detailed reaction mechanism, which includes all relevant chemiluminescence reactions and deactivation processes, is used. The result of the simulations is a lookup table of the ratio between heat release rate and OH* intensity with strain rate as parameter. This lookup table is linked with the statistical strain rate model to obtain a correction factor which accounts for the nonlinear relationships between OH* intensity, heat release rate, and strain rate. The factor is then used to correct measured OH* intensities to obtain the local heat release rate. The corrected intensities are compared to heat release distributions which are measured with an alternative method. For all investigated flames in the lean, partially premixed regime the corrected OH* intensities are in very good agreement with the heat release rate distributions of the flames.

Abstract 1550: Non-Doppler Two-Dimensional Strain Imaging for Early Detection of Heart Transplant Recipients with Coronary Stenoses

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Michael Dandel ◽  
Hans Lehmkuhl ◽  
Christoph Knosalla ◽  
Roland Hetzer
Keyword(s):  
Strain Rate ◽  
Wall Motion ◽  
Strain Imaging ◽  
Regional Strain ◽  
Strain And Strain Rate ◽  
Global Strain ◽  
2D Strain ◽  
Coronary Stenoses ◽  
2D Strain Imaging ◽  
Global Strain Rate

Background: Non-Doppler based two-dimensional (2D) strain imaging can reveal wall motion alterations not visible by conventional echocardiography (ECHO) and like tissue Doppler imaging (TDI) it can detect myocardial deformation (regional shortening and thickening) in the absence of visible ventricular wall displacement. Because TDI is dependent on the direction of Doppler angle of incidence in relation to myocardial motion, in our attempt to assess of the diagnostic value of strain and strain rate changes for early detection of transplant coronary arteriopathy (TCA), we focused our attention on the angle independent 2D strain imaging. Methods: In 68 heart recipients with normal LV wall motion and ejection fraction in conventional ECHO, 2D strain LV wall motion analysis were additionally performed before each follow-up cardiac catheterization. Circumferential, radial and longitudinal strain and strain rate were calculated from parasternal short axes and apical (3- and 4-chamber) views, respectively. 2D strain parameters were tested for relationships with angiographic findings. Results: In comparison with patients without TCA, those with angiographic TCA showed lower global systolic strain rate (radial, circumferential and longitudinal) values and longer systolic times measured from onset of contraction to the peak of systolic strain (p<0.01). For radial peak systolic global strain rate values below 1.1/s we found a 93.3% likelihood of angiographic TCA in general, regardless of the presence or absence of focal stenoses on main coronaries. Regional strain and strain rate analyses showed differences in contraction asynchrony and dyssynergy indexes between patients with and without focal stenoses (p<0.01). For longitudinal midsystolic dyssynchrony index values >0.5 we found an 88.2% likelihood of relevant focal coronary stenoses (>50% narrowing). Conclusions: In heart allografts with apparently normal LV kinetics in conventional ECHO, simple global strain rate measurements allow early TCA prediction, but without the ability to differentiate between diffuse TCA and predominantly focal coronary stenoses. Such differentiation is possible with more complex regional strain analyses using contraction asynchrony and dyssynergy indexes.

Determination of the Heat Release Distribution in Turbulent Flames by a Model Based Correction of OH* Chemiluminescence

2011 ◽  
Author(s):  
Martin Lauer ◽  
Mathieu Zellhuber ◽  
Thomas Sattelmayer ◽  
Christopher J. Aul
Keyword(s):  
Strain Rate ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Correction Method ◽  
Turbulent Flames ◽  
Lookup Table ◽  
Rate Model ◽  
Non Linear

Imaging of OH* or CH* chemiluminescence with intensified cameras is often employed for the determination of heat release in premixed flames. Proportionality is commonly assumed, but in the turbulent case this assumption is not justified. Substantial deviations from proportionality are observed, which are due to turbulence-chemistry interactions. In this study a model based correction method is presented to obtain a better approximation of the spatially resolved heat release rate of lean turbulent flames from OH* measurements. The correction method uses a statistical strain rate model to account for the turbulence influence. The strain rate model is evaluated with time-resolved velocity measurements of the turbulent flow. Additionally, one-dimensional simulations of strained counterflow flames are performed to consider the non-linear effect of turbulence on chemi-luminescence intensities. A detailed reaction mechanism, which includes all relevant chemiluminescence reactions and deactivation processes, is used. The result of the simulations is a lookup table of the ratio between heat release rate and OH* intensity with strain rate as parameter. This lookup table is linked with the statistical strain rate model to obtain a correction factor which accounts for the non-linear relationships between OH* intensity, heat release rate, and strain rate. The factor is then used to correct measured OH* intensities to obtain the local heat release rate. The corrected intensities are compared to heat release distributions which are measured with an alternative method. For all investigated flames in the lean, partially premixed regime the corrected OH* intensities are in very good agreement with the heat release rate distributions of the flames.

scholarly journals Global strain rate imaging for the estimation of diastolic function in HFNEF compared with pressure-volume loop analysis

2010 ◽  
Vol 11 (9) ◽  
pp. 743-751 ◽  
Author(s):  
M. Kasner ◽  
R. Gaub ◽  
D. Sinning ◽  
D. Westermann ◽  
P. Steendijk ◽  
...  
Keyword(s):  
Strain Rate ◽  
Diastolic Function ◽  
Loop Analysis ◽  
Strain Rate Imaging ◽  
Global Strain ◽  
Global Strain Rate

Speckle Tracking Global Strain Rate E/E′ Predicts LV Filling Pressure More Accurately Than Traditional Tissue Doppler E/E′

2011 ◽  
Vol 29 (4) ◽  
pp. 404-410 ◽  
Author(s):  
Koichi Kimura ◽  
Katsu Takenaka ◽  
Aya Ebihara ◽  
Tomoko Okano ◽  
Kansei Uno ◽  
...  
Keyword(s):  
Strain Rate ◽  
Speckle Tracking ◽  
Tissue Doppler ◽  
Filling Pressure ◽  
Global Strain ◽  
Global Strain Rate

Abstract 2490: Non-uniformity of Three-dimensional Left Ventricular Relaxation Abnormalities in Hypertensive Left Ventricular Hypertrophy by Speckle Tracking Global Strain Rate Imaging

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Takeshi Takamura ◽  
Kaoru Dohi ◽  
Katsuya Onishi ◽  
Naoki Fujimoto ◽  
Tairo Kurita ◽  
...  
Keyword(s):  
Left Ventricular Hypertrophy ◽  
Strain Rate ◽  
Speckle Tracking ◽  
Ventricular Hypertrophy ◽  
Systolic Function ◽  
Left Ventricular ◽  
Strain Rate Imaging ◽  
Global Strain ◽  
Lv Systolic Function ◽  
Global Strain Rate

Background: We tested the hypothesis that global strain rate imaging can quantify and stratify the severity of left ventricular (LV) relaxation abnormality in patients with left ventricular hypertrophy (LVH) ranged from normal to reduced LV systolic function independently from longitudinal (L), circumferential (C), and radial axes (R). Methods: Fifty-seven patients with hypertensive LVH and thirty age matched controls (Control, EF 65 ± 5 %) had echo-study with speckle tracking strain and strain rate imaging from (L), (C), and (R). LVH were divided into two groups; normal EF (LVH-NEF) defined as EF ≥ 55% (n = 35, EF 64 = 5 %), and systolic dysfunction (LVH-SD) defined as EF < 55% (n = 22, EF 48 ± 8 %). Global peak systolic strain (PSS) and peak relaxation rate (PRR) were used as indices of global LV contraction and relaxation, respectively (Vivid 7 and EchoPAC, GE Electronic). Results: PSS was maintained in LVH-NEF but reduced in LVH-SD from all three perpendicular axes. PRR (L) was impaired in LVH-NEF and was further decreased in LVH-SD (0.95 ± 0.33* and 0.58 ± 0.24* † 1/s, *p <0.05 vs. Control and † p <0.05 vs. LVH-NEF, respectively)compared to Control (1.14 ± 0.30 1/s). PRR (C) was maintained in LVH-NEF but reduced in LVH-SD (1.24 ± 0.50 and 0.73 ± 0.36 1/s*, p <0.05 vs. Control) compared to Control (1.30 ± 0.48 1/s). PRR (R) was impaired in both LVH-NEF and LVH-SD in the same degrees (-1.53 ± 0.60* and -1.27 ± 0.64* 1/s, p <0.05 vs. Control: -2.08 ± 0.84 1/s). Conclusion: Speckle tracking strain rate imaging quantified and stratified the severity of LV relaxation abnormality in patients with LVH ranged from normal to reduced LV systolic function independently from all three perpendicular ventricular axes.

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