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ItemNo Preview AvailableEffect of solid surface in vicinity of multi-bubble array in cryogenic environmentMondal, J ; Mishra, A ; Lakkaraju, R ; Ashokkumar, M ; Ghosh, P (IOP PUBLISHING LTD, 2020-01-01)Abstract Multiple bubble interactions in initially quiescent liquid are often accompanied by generation of jets, shockwaves and light. At cryogenic temperature (< 123 K) when certain materials (particularly bcc-type) become brittle, such afore-mentioned physical effects can be effective in disintegrating them to smaller fragments. CFD techniques based on direct numerical simulations can help to understand this phenomenon that may benefit nanotechnology-based industries and oil-gas exploration-firms working with air-gun arrays. In this paper, multiple bubble-pairs are simulated in a co-centric manner around a centrally located solid target (5 mm radius). The ambient fluid is liquid nitrogen (77 K) and the bubbles are gaseous nitrogen (87 K). 2D numerical simulation using the VOF method in compressible domain is carried out neglecting the effect of phase change and gravity. The stand-off distance between the solid target and bubble-pairs are varied systematically and its influence on the fluid-dynamic effects (e.g. pressure shockwave & jets) are compared. Initial calculations suggest that for stand-off distance of 0.93 mm, shockwaves measure above 10 times the ambient pressure and liquid jet speeds around 30 m/s in cryogenic environment, at multiple locations very close to the solid target. These consecutive physical impacts can foster ample liquid-hammer pressures, making it promising for solid wear at 77 K when juxtaposed against room-temperature cases.
ItemNo Preview AvailableArtist oil paints in ThailandTSE, NA ; Chayabutra, S ; Kamolchote, K ; Panmanee, S ; Khlungwisarn, T ; Puskar, L ; Best, SP (International Council of Museums, 2014-09-14)The deterioration of artist paints and paintings in Thailand’s tropical climate is unique. This paper outlines the research and production of Pradit oil paints by Thailand’s Silpakorn University, which are manufactured in collaboration with artists, researchers, scientists and conservators. Following eight years of natural ageing in Thailand and three years in Melbourne, Australia, the paint films were technically and analytically examined to identify the oil paints more susceptible to the effects of climate. Lightfastness, solubility, crack patterns, contact angle and the real time response of oil paint films to moisture identified the more susceptible paints. Fourier transform infrared (FTIR) with attenuated total reflectance (ATR) and synchrotron radiation FTIR microspectroscopy (SR-μFTIR) identified the signatures associated with chemical changes in the paint films. Given the harsh climatic conditions in tropical Thailand, the integrated study aims to provide artists with a wider range of painting choices and for materials scientists and conservators to approach preservation issues in the region from a proactive, informed position.
ItemPolarisation to colour transformation via nano-antenna enhanced quantum dot emissionJames, TD ; Panchenk, E ; Nguyen, TL ; Mulvaney, P ; Davis, TJ ; Roberts, A ; Faraone, L ; Martyniuk, M (IEEE, 2014-01-01)