Search results for " Bubbles"

Local gas-liquid hold-up and interfacial area via light sheet and image analysis

2010

Particle Image Velocimetry techniques coupled with advanced Image Processing tools are receiving an increasing interest for measuring flow quantities and local bubble-size distributions in gas-liquid contactors. In this work, an effective experimental technique for measuring local gas hold-up and interfacial area, as well as bubble size distribution, is discussed. The technique, hereafter referred to as Laser Induced Fluorescence with Shadow Analysis for Bubble Sizing (LIF-SABS) is based on laser sheet illumination of the gas-liquid dispersion and synchronized camera, i.e. on equipment typically available within PIV set-ups. The liquid phase is made fluorescent by a suitable dye, and an opt…

Detection potential of the KM3NeT detector for high-energy neutrinos from the Fermi bubbles

2013

A recent analysis of the Fermi Large Area Telescope data provided evidence for a high-intensity emission of high-energy gamma rays with a E-2 spectrum from two large areas, spanning 50 above and below the Galactic centre (the "Fermi bubbles"). A hadronic mechanism was proposed for this gamma-ray emission making the Fermi bubbles promising source candidates of high-energy neutrino emission. In this work Monte Carlo simulations regarding the detectability of high-energy neutrinos from the Fermi bubbles with the future multi-km(3) neutrino telescope KM3NeT in the Mediterranean Sea are presented. Under the hypothesis that the gamma-ray emission is completely due to hadronic processes, the resul…

CFD prediction of bubbles local gas hold-up in 2-dimensional gas-solid fluidized beds

2008

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…

On the bubbling dynamics of binary mixtures of powders in 2D gas-solid fluidized beds

2012

Abstract The bubbling behavior of fluidized beds has been thoroughly investigated in the last decades by means of several techniques (e.g. X-ray, Inductance, Resistance and Impedance based techniques). In recent years, Digital Image Analysis Techniques have shown their potential for accurate and cost effective measurements. Most of the works related to the experimental analysis of bubble behavior in the field of gas-solid fluidization actually deal with monodispersed particles although almost all industrial equipments operate with mixtures of particles. Among the works available in literature dealing with mixtures of particles having different diameters and/or densities, most of them aim at…

Statistical validation of investment decisions and transactions in financial markets

Digitālo mediju ietekme uz lēmumu pieņemšanu un demokrātiju

2018

Mūsdienās tādu tehnoloģiju progress kā mākslīgais intelekts apvienojumā ar Lielo Datu analīzi ir devis iespēju ievākt, uzturēt un analizēt milzīgus datu apjomus. Progress digitālajā jomā ietekmē ne tikai tirgus ekonomiku, bet arī politisko līdzdalību. Digitālie mediji spēj apvienot līdzīgi domājošos, iedrošināt sociālas aktivitātes, mazināt plaisas starp sabiedrības grupām, kā arī paaugstināt politisko līdzdalību valstī un veicināt izglītību, tomēr ir pastiprinātas bažas par to, ka digitālo mediju platformas var tikt izmantotas, lai izplatītu propagandas vēstījumus, kas is spējīga piesaistīt lielu auditoriju. Automātiskajiem filtrēšanas mehānismiem var piemist diskriminējošs raksturs, ietek…

A search for neutrino emission from the Fermi bubbles with the ANTARES telescope

2014

Adrián-Martínez, S. et al.

Bubbles in China

2010

This study examines rational bubbles in Chinese stock markets and China-related share indices in Hong Kong. A duration dependence test is employed for both monthly and weekly abnormal market returns of the Shanghai and Shenzhen A- and B-markets, as well as for the Hong Kong China Enterprises and China Affiliated Corporations indices. The test results are mixed, as weekly data demonstrate bubbles for all of the Mainland Chinese stock markets, but monthly data do not show bubbles for any of the examined markets. Neither of the datasets indicates bubbles in the Hong Kong markets. Results indicate that, in terms of bubbles, segmentation does not play a significant role in bubble existence and t…

Mode-particle Interactions as Sources of Gamma-ray Bubbles in the Galaxy

A plasma outflow coming from the center of Our Galaxy is simulated by an ion beam reaching a nearly stationary magnetic field that can excite lower hybrid waves efficiently in the rarefied plasma (10-2-10-4 cm-3) surrounding the whole galaxy. The electrostatic lower hybrid waves are driven to instability via Cerenkov interaction. In this work we derive (by using a fluid model) the relevant dispersion relation and the expression for the growth rate by solving the dispersion relation both analytically and numerically. Parametric studies show that the growth rate of the instability increases with the beam density. The instability is found to have the maximum growth rate when the perpendicular …