Wyniki wyszukiwania - BazTech

1

Tracking the transport of pollutants by means of imaging methods

Molteni Perez Francisco, Aleixo Rui, Gubler Alejandra, Winckler Patricio, Reyes Mauricio

Acta Geophysica

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2022

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Vol. 70, no 5

2437--2450

EN

A method for identification and tracking of pollutants plumes in water is presented and applied to laboratory data. This method uses the intensity threshold and associated image processing algorithms to identify the pollutant’s plume within a footage. Quantitative geometrical parameters are then extracted on each frame as proxies of the turbulent diffusion (i.e. area and perimeter) and advection (i.e. centroid location). From the determined plume location in each frame, it is then possible to devise a tracking algorithm which can determine the trajectory and eventual fate of the plume. The developed method is applied to two different types of plumes: one generated by a liquid pollutant (rhodamine) and another by a granular matrix type material (coal) to compare its capability of tracking different plumes. Although developed with laboratory images, the presented method is general and can be applied to field images as well. The advantages and limitations of the proposed methodology are also discussed.

2

A study on magnetic field assisted laser percussion drilling and its effect on surface integrity

Balamurugan S., Manikandan C. B., Balamurugan P.

Archives of Materials Science and Engineering

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2018

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Vol. 94, nr 1

35--40

EN

Purpose: of this paper is to reduce the taper angle and surface roughness of the laser drilled hole on Aluminium alloy with the assistance of magnetic field. At lower laser powers, able to achieve higher material removal rate in drilling with reduced taper angle and roughness. Design/methodology/approach: Aluminium alloy is a highly reflective material, while laser drilling it ejects plumes, which makes the drilling unreliable. The plume generated due to this action causes deteriorating effects over the work piece as such affecting surface textures. Removal of plume is the major consideration in laser machining process, especially in laser assisted drilling. The plume is a form of cluster of ions having charges in it. Due to the magnetic field input, the ions line the path along the lines of force of magnets. Thus, the ion cloud can be cleared at the localized plane, where the subsequent laser drilling going to be happens, leads to reduced plume thereby reduces the taper angle and surface roughness. Findings: The defect of percussion laser drilling that is barrelling effect in the drilled hole was reduced with the assistance of magnetic field setup. For the laser energy of 90 mJ, the magnetic assisted laser drilling shows better improvement in the material removal rate of 64.5%, the profile error (spatter height) was reduced to 45% and the taper angle of the drilled hole also reduced by 16.3%. The results confirmed the fact that, the Lorentz force confined the plume particle to be raised upwards and circulated outwards to the sidewall from the centre of the laser beam. This expansion of laser induced plasma plume, improved the material removal rate of the hole. Research limitations/implications: Laser drilling was carried out by a constant magnetic field and the parameters like material removal rate, taper angle, profile error, surface roughness were studied. In the future work, these parameters were studied with the application of varying magnetic field. Practical implications: As a result of the work, laser drilling was carried out on turbine blades or complex shapes for retention properties, with reduced taper hole and surface roughness, thereby improving the efficiency of the systems. Originality/value: The novelty of the work is providing magnetic flux for the laser drilling process, which improves the process parameters. The incorporation of magnetic field to the laser drill needs a cost less setup, which can ensure reliable improvement in the material removal rate, reduction in taper angle and profile error.

3

Swarms in Andaman Sea, India - a seismotectonic analysis

Mukhopadhyay B., Dasgupta S.

Acta Geophysica

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2008

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Vol. 56, no. 4

1000-1014

EN

The seismotectonic characteristics of 1983–1984, 1993 and 2005 swarms in Andaman Sea are analysed. These swarms are characterised by their typical pulsating nature, oval shaped geometry and higher b values. The migration path of the swarms from north to south along the Andaman Spreading Ridge is documented. While the first two swarms are located along existing mapped rift segments, the 2005 swarm appears to have generated a new rift basin along 8°N. The analysis and supporting evidences suggest that these swarms were generated by intruding magmatic dyke along the weak zones in the crust, followed by rifting, spreading and collapse of rift walls. CMT solutions for 2005 swarm activity indicate that intrusion of magmatic dyke in the crustal weak zone is documented by earthquakes showing strike slip solution. Subsequent events with normal fault mechanism corroborate the rift formation, collapse and its spreading.