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Articles 61 - 63 of 63

Full-Text Articles in Engineering

The Soft X-Ray Background: Evidence For Widespread Disruption Of The Gas Haloes Of Galaxy Groups, K K S Wu, A C. Fabian, Paul E. J Nulsen Jan 2001

The Soft X-Ray Background: Evidence For Widespread Disruption Of The Gas Haloes Of Galaxy Groups, K K S Wu, A C. Fabian, Paul E. J Nulsen

Faculty of Engineering and Information Sciences - Papers: Part A

Almost all of the extragalactic X-ray background (XRB) at 0.25 keV can be accounted for by radio-quiet quasars, allowing us to derive an upper limit of 4 keV cm−2 s−1 sr−1 keV−1 for the remaining background at 0.25 keV. However, the XRB from the gas haloes of groups of galaxies, with gas removal resulting from cooling accounted for, exceeds this upper limit by an order of magnitude if non-gravitational heating is not included. We calculate this using simulations of halo merger trees and realistic gas density profiles, which we require to reproduce the observed gas fractions …


Values Of Minors Of An Infinite Family Of D-Optimal Designs And Their Application To The Growth Problem, C Koukouvinos, M Mitrouli, Jennifer Seberry Jan 2001

Values Of Minors Of An Infinite Family Of D-Optimal Designs And Their Application To The Growth Problem, C Koukouvinos, M Mitrouli, Jennifer Seberry

Faculty of Engineering and Information Sciences - Papers: Part A

No abstract provided.


Gas Emission Modelling Of Gate Road Development, R. J. Williams, E. Yurakov, D. J. Ashelford Jan 2001

Gas Emission Modelling Of Gate Road Development, R. J. Williams, E. Yurakov, D. J. Ashelford

Resource Operators Conference

This paper covers the modelling of gas emission during gate road development. Complexities related to the range of gas reservoir and mining data are briefly described. The rib emission response to initial gas reservoir parameters is defined using the SIMED II gas reservoir simulator. The rib emission decay curves are then used in an interactive EXCEL spreadsheet model that takes additional account of mining and ventilation parameters. It is an attempt at bringing to planners and mine operators an interactive tool that incorporates the important parameters and options.
SIMED’s strengths lie in it’s ability to:
• quickly convey a message …