Determination of flow distribution in a HCLL blanket mock-up through electric potential measurements

2011 ◽  
Vol 86 (9-11) ◽  
pp. 2301-2303 ◽  
Author(s):  
L. Bühler ◽  
C. Mistrangelo
Keyword(s):  
Electric Potential ◽  
Flow Distribution

Measurement of Intrarenal Blood-Flow Distribution in the Rabbit Using Radioactive Microspheres

1975 ◽  
Vol 48 (1) ◽  
pp. 51-60 ◽  
Author(s):  
D. J. Warren ◽  
J. G. G. Ledingham
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Renal Cortex ◽  
Flow Distribution ◽  
Rabbit Kidney ◽  
Radioactive Microspheres ◽  
Injection Dose ◽  
Intrarenal Blood Flow ◽  
Total Renal Blood Flow

1. Total renal blood flow and its distribution within the renal cortex of the conscious rabbit were studied with radioactive microspheres of 15 and 25 μm diameter. 2. The reliability of the microsphere technique was influenced by microsphere diameter and number (dose). The optimum microsphere diameter for determination of flow distribution in the rabbit kidney was 15 μm and dose 100–150 000 spheres. 3. Spheres of 15 μm nominal diameter were randomly distributed within the renal cortex of adult rabbits. The larger spheres in batches nominally 15 μm in diameter in young rabbits and 25 μm diameter in adult rabbits were preferentially distributed to the superficial cortex. 4. In adult rabbits 15 μm diameter spheres lodged in glomerular capillaries. Larger spheres occasionally lodged in interlobular arteries causing intrarenal haemorrhage. 5. Microspheres of 15 μm caused a decrease in renal clearance of creatinine and of p-aminohippurate when the total injection dose was about 200 000 spheres. These effects were greater when the injection dose was increased to 500 000 spheres. 6. The reduction in total renal blood flow observed with large doses of spheres largely reflected decreased outer cortical flow, as measured by a second injection of spheres, and confirmed by a decrease in p-aminohippurate extraction. 7. The reproducibility of multiple injection studies was limited by these intrarenal effects of microspheres. 8. Total renal blood flow measured in six rabbits in acute experiments by the microsphere technique was 107 ± 12 (mean±sd) ml/min and by p-aminohippurate clearance was 100 ± 10 ml/min. 9. Total renal blood flow in twelve conscious, chronically instrumented rabbits was 125 ± 11 ml/min, of which 92 ± 6 ml/min was distributed to the superficial cortex and 33 ± 4 ml/min to the deep cortex.

Blood flow distribution in working in situ canine muscle during blood flow reduction

1996 ◽  
Vol 80 (6) ◽  
pp. 1978-1983 ◽  
Author(s):  
S. S. Kurdak ◽  
B. Grassi ◽  
P. D. Wagner ◽  
M. C. Hogan
Keyword(s):  
Blood Flow ◽  
Muscle Blood Flow ◽  
Flow Distribution ◽  
Blood Flow Distribution ◽  
Strong Negative Correlation ◽  
Flow Heterogeneity ◽  
Blood Flow Reduction ◽  
Blood Flow Heterogeneity

The purpose of this study was to determine whether reduction in apparent muscle O2 diffusing capacity (Dmo2) calculated during reduced blood flow conditions in maximally working muscle is a reflection of alterations in blood flow distribution. Isolated dog gastrocnemius muscle (n = 6) was stimulated for 3 min to achieve peak O2 uptake (VO2) at two levels of blood flow (controlled by pump perfusion): control (C) conditions at normal perfusion pressure (blood flow = 111 +/- 10 ml.100 g-1.min-1) and reduced blood flow treatment [ischemia (I); 52 +/- 6 ml.100 g-1.min-1]. In addition, maximal vasodilation was achieved by adenosine (A) infusion (10(-2)M) at both levels of blood flow, so that each muscle was subjected randomly to a total of four conditions (C, CA, I, and IA; each separated by 45 min of rest). Muscle blood flow distribution was measured with 15-microns-diameter colored microspheres. A numerical integration technique was used to calculate Dmo2 for each treatment with use of a model that calculates O2 loss along a capillary on the basis of Fick's law of diffusion. Peak VO2 was reduced significantly (P < 0.01) with ischemia and was unchanged by adenosine infusion at either flow rate (10.6 +/- 0.9, 9.7 +/- 1.0, 6.7 +/- 0.2, and 5.9 +/- 0.8 ml.100 g-1.min-1 for C, CA, I, and IA, respectively). Dmo2 was significantly lower by 30-35% (P < 0.01) when flow was reduced (except for CA vs. I; 0.23 +/- 0.03, 0.20 +/- 0.02, 0.16 +/- 0.01, and 0.13 +/- 0.01 ml.100 g-1.min-1.Torr-1 for C, CA, I, and IA, respectively). As expressed by the coefficient of variation (0.45 +/- 0.04, 0.47 +/- 0.04, 0.55 +/- 0.03, and 0.53 +/- 0.04 for C, CA, I, and IA, respectively), blood flow heterogeneity per se was not significantly different among the four conditions when examined by analysis of variance. However, there was a strong negative correlation (r = 0.89, P < 0.05) between Dmo2 and blood flow heterogeneity among the four conditions, suggesting that blood flow redistribution (likely a result of a decrease in the number of perfused capillaries) becomes an increasingly important factor in the determination of Dmo2 as blood flow is diminished.

scholarly journals Numerical Model for Simulation of the Cathodic Protection System with Dynamic Nonlinear Polarization Characteristics

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Numerical Model ◽  
Current Density ◽  
Cathodic Protection ◽  
Electric Potential ◽  
Protection System ◽  
Nonlinear Polarization ◽  
Electrode Surfaces ◽  
Polarization Characteristics ◽  
Cathodic Protection System

Cathodic protection is defined as a method for slowing down or complete elimination of corrosion processes on underground or underwater, insulated or uninsulated metal structures. Protection by cathodic protection system is achieved by polarizing protected object to more negative value, with respect to its equilibrium potential. Design of the cathodic protection system implies determination of the electric potential and current density on the electrode surfaces after installation of the cathodic protection system. Most efficient way for determination of the electric potential and current density in the cathodic protection system is by applying numerical techniques. When modeling cathodic protection systems by numerical techniques, electrochemical reactions that occur on electrode surfaces are taken into account by polarization characteristics. Because of nature of the electrochemical reactions, polarization characteristics are nonlinear and under certain conditions can be time – varying (dynamic nonlinear polarization characteristics). This paper deals with numerical modeling of the cathodic protection system with dynamic nonlinear polarization characteristics. Numerical model presented in this paper is divided in the two parts. First part, which is based on the direct boundary element method, is used for the calculation of the distribution of electric potential and current density on the electrode surfaces in the spatial domain. Second part of the model is based on the finite difference time domain method and is used for the calculation of the electric potential and current density change over time. The use of presented numerical model is demonstrated on two simple geometrically examples.

Suppression of turbulence in the drift-resistive plasma where zonal flow changes direction

2020 ◽  
Vol 86 (3) ◽  
Author(s):  
Chang-Bae Kim
Keyword(s):  
Electric Potential ◽  
Zonal Flow ◽  
Equilibrium Density ◽  
Turbulence Level ◽  
Edge Region ◽  
Transport Barrier ◽  
Large Gradient ◽  
Resistive Plasma ◽  
Flow Changes

The edge region of quasi-adiabatic plasma is pedagogically simulated by the dynamics between the electric potential $\unicode[STIX]{x1D711}$ and the electron density $n$ whose equilibrium density gradient is negative and held fixed. The zonal flow (ZF) $V$ is either enforced sinusoidally or generated self-consistently from the turbulence. Cross-phase $\unicode[STIX]{x1D6FF}$ between $\unicode[STIX]{x1D711}$ and $n$ , which is important in the determination of the turbulence level and the transport, is strongly influenced by the ZF. In the region near $V=0$ , $\unicode[STIX]{x1D6FF}$ becomes negative due to the large gradient of the ZF. It is found that the instabilities are quenched there, and the fluctuations decay. The ZF thus works as a transport barrier in the region where the ZF changes direction with large gradient.

Diagnostic angioscintigraphic evaluation of malignant hepatic tumors before catheter embolization: Determination of shunt, flow distribution, and reflux

1996 ◽  
Vol 19 (2) ◽  
pp. 77-81 ◽  
Author(s):  
René H. Walser ◽  
Andreas R. Haldemann ◽  
Helmuth Rösler ◽  
Pavel Koranda ◽  
Jane A. Kinser ◽  
...  
Keyword(s):  
Flow Distribution ◽  
Hepatic Tumors ◽  
Shunt Flow ◽  
Catheter Embolization

Determination of the Anode Flow Distribution in a SOFC Stack at Nominal Operating Conditions by EIS

2019 ◽  
Vol 25 (2) ◽  
pp. 1871-1878 ◽  
Author(s):  
Nico Dekker ◽  
J. F. Van Wees ◽  
B. G. Rietveld
Keyword(s):  
Flow Distribution ◽  
Operating Conditions

scholarly journals Determination of the band structure diagram of semiconductor heterostructures applied in photovoltaics

2021 ◽  
Vol 51 (1) ◽  
Author(s):  
Rafał Antoni Bogaczewicz ◽  
Ewa Popko ◽  
Katarzyna Renata Gwóźdź
Keyword(s):  
Band Structure ◽  
Electric Potential ◽  
Energy Band ◽  
Theoretical Calculations ◽  
Energy Band Diagram ◽  
Depletion Region ◽  
Semiconductor Heterostructures ◽  
Band Diagram ◽  
Approximation Model

Recently it has been found that the heterostructures of n-ZnO/p-Si are promising photovoltaic alternatives to silicon homojunctions. It is well known that the energy band diagram of a heterostructure is crucial for the understanding of its operation. This paper analyzes the ZnO/p-Si heterostructure band by using free AMPS-1D computer program simulations. The obtained numerical results are compared with theoretical calculations based on the depletion region approximation model and the Poisson’s equation for electric potential. The results of the simulation are also compared with the experimental C-V characteristics of the test n-ZnO/p-Si heterostructure. The simulated C-V characteristics is qualitatively consistent with the experimental C-V curve, which confirms the correctness of the determined band diagram of the n-ZnO/p-Si heterostructure.

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