Search results for "BUBBLE"
showing 10 items of 167 documents
Spatial dispersion intensity measure of phase concentration distributions and its applications to quantitative characterization, distinguishing and c…
2008
A method of evaluation of spatial dispersion of structures is presented. A quantitative parameter measuring spatial dispersion is introduced. It is shown that this parameter indeed measures spatial dispersion. A classification of bubble flow structures based on values of this parameter is proposed. An example of application of the method to real flow structures is presented.
Heterogeneous delayed enhancement of hepatic parenchyma after intravenous infusion of sonographic contrast agent: a new hypothesis
2007
Purpose. The aim of this paper was to report a heterogeneous latephase hepatic enhancement pattern observed after administration of a sonographic contrast agent and to present an aetiological hypothesis for the phenomenon. Materials and methods. A total of 1,729 (1,012 women and 717 men; age range 28–82; mean age 51) patients underwent contrastenhanced sonography of the liver. The examination was performed with a low mechanical index (MI <0.09) after injection of sulphur-hexafluoride-filled microbubbles, using different fonographic equipment and different contrast-specific algorithms. Results. Heterogeneous delayed liver enhancement was observed in six patients in the late phase (180 s), wi…
Skyrmion-number dependence of spin-transfer torque on magnetic bubbles
2015
We theoretically study the skyrmion-number dependence of spin-transfer torque acting on magnetic bubbles. The skymrion number of magnetic bubbles can take any integer value depending on the magnetic profile on its circumference and the size of the bubble. We find that the transverse motion of a bubble with respect to the charge current is greatly suppressed as the absolute value of the skyrmion number departs from unity, whereas the longitudinal motion is less sensitive.
Prompt TeV Emission from Cosmic Rays Accelerated by Gamma Ray Bursts Interacting with Surrounding Stellar Wind
2009
11 pages, 1 figure.--ISI article identifier:000263148600009.-- ArXiv pre-print avaible at:http://arxiv.org/abs/0810.1287
Modelling and Simulation of Gas–liquid Hydrodynamics in a Rectangular Air-lift Reactor
2013
Abstract Computational Fluid Dynamics is a quite well established tool for carrying out realistic simulations of process apparatuses. However, as a difference from single phase systems, for multiphase systems the development of CFD models is still in progress. Among the two-phase systems, gas–liquid systems are characterised by an additional complexity level, related to the fact that bubble sizes are not known in advance, being rather the result of formation and breakage-coalescence dynamics and therefore of complex phenomena related to flow dynamics and interfacial effects. In the present work, Euler–Euler Reynolds-averaged flow simulations of an air-lift reactor are reported. All bubbles …
Numerical model for the shear rheology of two-dimensional wet foams with deformable bubbles
2014
Shearing of two-dimensional wet foam is simulated using an introduced numerical model, and results are compared to those of experiments. This model features realistically deformable bubbles, which distinguishes it from previously used models for wet foam. The internal bubble dynamics and their contact interactions are also separated in the model, making it possible to investigate the effects of the related microscale properties of the model on the macroscale phenomena. Validity of model assumptions was proved here by agreement between the simulated and measured Herschel-Bulkley rheology, and shear-induced relaxation times. This model also suggests a relationship between the shear stress and…
Involvement of Jugular Valve Insufficiency in Cerebral Venous Air Embolism
2007
Background. Cerebral venous air entrapment is a rare finding on cranial computed tomography (CT) scan. Peripheral air embolism is discussed as a potential cause. However, the mechanism of retrograde passage through internal jugular valves and veins is unclear. Case Report. The case of a patient is reported, who had air entrapment in the left cavernous sinus. Prior to CT scanning, a peripheral intravenous line had been placed. Ultrasound revealed excessive insufficiency of the left internal jugular valve. To further study the mechanism of embolism, an echo contrast agent was injected into the cubital vein. A Valsalva maneuver resulted in retrograde transition of microbubbles across the insuf…
Myocardial contrast echocardiography in biopsy-proven primary cardiac amyloidosis.
2008
Abstract Cardiac vasculature is affected in 88-90% of patients with primary cardiac amyloidosis (CA). Myocardial contrast echocardiography (MCE) relies on the ultrasound detection of microbubble contrast agents that are solely confined to the intravascular space, and are therefore useful in the evaluation of flow in the microvasculature. This is the first case report describing the use of MCE during vasodilator stress to evaluate coronary flow reserve in a patient with biopsy-proven primary CA and angiographically normal coronaries. Qualitative MCE demonstrated delayed replenishment of microbubbles during peak stress; quantitative analysis was consistent with a reduction in total myocardial…
Experimental study of bubble detection in liquid metal.
2017
International audience; Bubble detection in liquid metal is an important issue for various technological applications. For instance, in the framework of Sodium Fast Reactors design, the presence of gas in the sodium flow of the primary and secondary loops is an issue of crucial importance for safety and reliability. Here, the two main gas measurement methods in sodium are ultrasonic testing and eddy-current testing; we investigate the second method in our study. In a first approach, we have performed experiments with liquid metal galinstan containing insulating spherical beads of millimeter size. The liquid metal is probed with an Eddy-current Flowmeter (ECFM) in order to detect the beads a…
Determination of Bubble Size Distribution Using Ultrasound Array Imaging
2020
In this article, ultrasonic phased arrays are deployed as an imaging tool for industrial process analysis. Such arrays are typically used for sonar, medical diagnosis, and nondestructive testing; however, they have not yet been applied to industrial process analysis. The precise positioning of array elements and high frequencies possible with this technology mean that highly focused images can be generated, which cannot currently be achieved using ultrasound tomography. This article aims to highlight the potential of this technology for the measurement of bubble size distribution (BSD) and to demonstrate its application to both intrusive and noninvasive process measurements. Ultrasound imag…