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Start Over Topic kinetic energy Language italian
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1. THE NATURE OF EROSIVE RAINFALL ON A TROPICAL VOLCANIC ISLAND WITH AN ELEVATED INTERIOR.

Author

Nel, Werner, Mongwa, Themba, Sumner, Paul D., Anderson, Ryan L., Dhurmea, Kumar R., Boodhoo, Yadowsun, Boojhawon, Ravi, and Rughooputh, Soonil D. D. V.

Subjects
SEDIMENTATION & deposition, SOIL erosion, ENVIRONMENTAL degradation, RAINFALL, CYCLONES
Abstract

Mauritius is a typical tropical volcanic island with a distinct elevated central plateau above 550 m.a.s.l. Rainfall depth, duration, intensity, kinetic energy, and erosivity were analysed for 385 erosive rainfall events at five locations over a five-year period (2004 to 2008). Two Mauritius Meteorological Services stations located on the west coast and three sited on the Central Plateau provide detailed rainfall data at 6-minute intervals. Erosive storm events are found to differ markedly between the coastal lowlands and the elevated interior with regard to the frequency, the total rainfall generated, the duration, total kinetic energy, and total erosivity of individual events. However, mean kinetic energy, mean and maximum rainfall erosivity (El10), and maximum intensities (I30) from individual erosive events do not show this distinct differentiation. The distribution of kinetic energy and erosivity generated by individual events at the two altitudes are also significantly different. Although erosivity measured during summer exceeds that recorded in winter, the data indicate that large percentages of winter rainfall events on Mauritius are erosive and rainfall from non-tropical cyclones can pose a substantial erosion risk. Soil erosion risk occurs from storm-scale to synoptic-scale events, and extreme rainfall events generate the bulk of the erosivity. This paper also highlights that the use of rainfall records at an event scale in soil erosion risk assessments on tropical islands with a complex topography increases the effectiveness of erosivity estimates. [ABSTRACT FROM AUTHOR]

Published
2012
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2. Quality factors assessed by analytical modelling in laser cutting

Author

Giovanni Tani, Alessandro Fortunato, Giampaolo Campana, Luca Tomesani, TANI G., TOMESANI L., CAMPANA G., and FORTUNATO A.

Subjects
Laser cutting, Chemistry, LASER CUTTING, Dross, STRIATION, Metals and Alloys, Process (computing), Surfaces and Interfaces, Mechanics, DROSS, KERF GEOMETRY MELT, Kinetic energy, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Quality (physics), Gas pressure, Materials Chemistry, Forensic engineering, CUTTING QUALITY, Striation, Energy (signal processing)
Abstract

Although striations and dross are the most significant quality factors in laser cutting operations, the mechanics of their formation is not yet entirely clear. In this paper striation and dross formation are analysed by means of an analytical model which, by considering mass, force and energy balances, evaluates the 3D geometry of the cutting front, and the geometry and temperature fields of the melt film. On this basis, an interpretation for the striation pattern based on the evolution of the melt film is proposed, thus allowing prediction of the well-known transition from single slope at low process speeds to double slope at high speeds. In the same way, the effect of the assistant gas pressure is predicted, in accordance with experimental observations by many authors. The mechanics of dross formation is also discussed, by introducing the kinetic energy of the melt film and relating it to the local temperature.

Published
2004