Determination of pulmonary mean transit time and cardiac output using a one-dimensional model

1996 ◽  
Vol 58 (6) ◽  
pp. 1155-1170 ◽  
Author(s):  
C. Le Sech ◽  
A. Capderou
Keyword(s):  
Cardiac Output ◽  
Transit Time ◽  
Mean Transit Time ◽  
Dimensional Model ◽  
One Dimensional

Determination of central blood volume. Comparison of Stewart-Hamilton method with direct measurements in dogs

1959 ◽  
Vol 196 (3) ◽  
pp. 499-501 ◽  
Author(s):  
Robert C. Schlant ◽  
Paul Novack ◽  
William L. Kraus ◽  
Charles B. Moore ◽  
Florence W. Haynes ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Blood Volume ◽  
Transit Time ◽  
Mean Transit Time ◽  
Total Radioactivity ◽  
Indicator Dilution ◽  
Dilution Method ◽  
Central Blood Volume ◽  
Volume Comparison ◽  
Direct Measurements

Central blood volume (cardiac output times mean transit time) from right atrium to ascending aorta was determined by the indicator-dilution method in 22 open-chested dogs which had previously had their red blood cells tagged with Cr51. The actual amount of blood in the heart and lungs was calculated from the total radioactivity in the blended homogenate of these organs. The two measurements of central blood volume correlated well ( r = +.88), the indicator-dilution volumes averaging 12% greater. The discrepancy between measurements is probably related to the pulmonary circuit having a lower hematocrit than the large vessels. The results substantiate the use of the Stewart-Hamilton formula (cardiac output times mean transit time) to measure central blood volume.

Effects of serotonin on pulmonary blood volume in the dog

1962 ◽  
Vol 202 (5) ◽  
pp. 957-960 ◽  
Author(s):  
Charles J. McGaff ◽  
William R. Milnor
Keyword(s):  
Cardiac Output ◽  
Blood Volume ◽  
Vascular Resistance ◽  
Transit Time ◽  
Mean Transit Time ◽  
Dilution Method ◽  
Continuous Intravenous Infusion ◽  
Pulmonary Blood Volume ◽  
Control Value ◽  
Vascular Bed

Changes in pulmonary blood volume produced by continuous intravenous infusion of serotonin (5-hydroxytryptamine) were measured in 16 experiments on ten dogs. Pulmonary mean transit time was measured by the dye dilution method, using consecutive injections into pulmonary artery and left atrium; pulmonary blood volume was calculated by multiplying this mean transit time by the cardiac output. Serotonin lowered pulmonary blood volume by an average of 2.9 ml/kg, or 26% of the control value ( P <0.001). Pulmonary vascular resistance increased 94 ru (resistance units) kg, and systemic vascular resistance fell 294 ru kg, effects similar to those reported by other investigators. The magnitude of the decrease in pulmonary blood volume indicates that a relatively large part of the pulmonary vascular bed is constricted by serotonin, and provides an example of shifting of blood from pulmonic to systemic circuits by reciprocal changes in the distensibility of these beds.

scholarly journals INVERSE PROBLEM OF A ONE-DIMENSIONAL MODEL IN MULTILAYER HEAT CONDUCTION

2020 ◽  
Vol 19 (1) ◽  
pp. 42
Author(s):  
G. C. Oliveira ◽  
S. S. Ribeiroa ◽  
G. Guimarães
Keyword(s):  
Inverse Problem ◽  
Measurement Errors ◽  
Input Data ◽  
Temperature Measurements ◽  
Dimensional Model ◽  
One Dimensional ◽  
Ill Posed ◽  
Measurements Errors ◽  
Chip Chip

The inverse problem in conducting heat is related to the determination of the boundary condition, rate of heat generation, or thermophysical properties, using temperature measurements at one or more positions of the solid. The inverse problem in conducting heat is mathematically one of the ill-posed problems, because its solution extremely sensitive to measurement errors. For a well-placed problem the following conditions must be satisfied: the solution must exist, it must be unique and must be stable on small changes of the input data. The objective of the work is to estimate the heat flux generated at the tool-chip-chip interface in a manufacturing process. The term "estimation" is used because in the temperature measurements, errors are always present and these affect the accuracy of the calculation of the heat flow.

scholarly journals APPLICATION OF SUPERELEMENTS IN STATIC ANALYSIS OF THIN‐WALLED STRUCTURES

2004 ◽  
Vol 10 (2) ◽  
pp. 113-122
Author(s):  
Ireneusz Kreja ◽  
Tomasz Mikulski ◽  
Czeslaw Szymczak
Keyword(s):  
Static Analysis ◽  
Standard Procedure ◽  
Dimensional Model ◽  
Fem Model ◽  
Shell Elements ◽  
One Dimensional ◽  
Thin Walled Structures ◽  
Thin Walled ◽  
Proper Solutions

A concept of a beam superelement is suggested as a new tool in the static analysis of structures made of thin‐walled members. This proposal seems to be especially attractive for treating the problems where the existing one‐dimensional models do not provide proper solutions. This class of problems includes, for instance, the torsion of thin‐walled beams with battens and the determination of the bimoment distribution at the nodes of frames made of thin‐walled members. The entire segment of the thin‐walled beam with warping stiffener or the whole node of the frame is modelled with shell elements. The stiffness matrix of such thin‐walled beam superelement can be estimated according to the standard procedure of the enforced unit displacements. The accuracy of the proposed one‐dimensional model has proved to be comparable to that offered by the detailed FEM model where the whole structure is represented by a very large number of shell elements.

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