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- Power, M. J., et al.
(författare)
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Changes in fire regimes since the Last Glacial Maximum : an assessment based on a global synthesis and analysis of charcoal data
- 2008
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Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 30:7-8, s. 887-907
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Tidskriftsartikel (refereegranskat)abstract
- Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ∼11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ∼19,000 to ∼17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ∼13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ∼3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.
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- Addie, Graeme, et al.
(författare)
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Pipeline design characteristics of some industrial paste-like slurries
- 2005
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Ingår i: Conference Proceedings - First Extractive Metallurgy Operators' Conference. - : The Australian Institute of Mining and Metallurgy. ; , s. 147-154
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Konferensbidrag (refereegranskat)abstract
- There is a wide variety of industrial pastes or non-settling slurries pumped in mining, dredging and reclamation projects as products, refuse and tails. The types and/or names of some of the common ones are alumina red mud, phosphate clays, tar sands mature fine tails, tar sands (CT) consolidated clays and fly ash. The pipeline performance or friction of these varies dramatically with the type, its concentration and the particulars of the actual slurry making it difficult to select pumping equipment and to design associated pipelines. The GIW Hydraulic Laboratory in Grovetown Georgia has tested a number of these slurries over the last 30 years for various mining customers. Where available in the public domain and/or where permission has been obtained, the results of those tests are presented in this paper in a form usable for pipeline and pump system designers and users.
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- Sellgren, Anders, et al.
(författare)
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The feasibility of transporting contaminated sediments as a slurry using centrifugal pumps
- 2005
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Ingår i: Remediation of contaminated sediments--2005. - Columbus, Ohio : Battelle Press.
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Konferensbidrag (refereegranskat)abstract
- Pumping a simulated sediment slurry at a low water content has been investigated at the GIW Hydraulic Testing Laboratory in a 3 inch (0.075 m) diameter loop with a centrifugal pump with an auger-like inducer. The results and earlier reported data from the Laboratory indicate that viscous sediments characterized by yield stresses in the range of about 2 to 4 psf (100 to 200 Pa) can be pumped effectively with centrifugal pumps. With yield stresses of up to 4 psf (200 Pa), the pressure requirement to overcome pipe friction for pipeline diameters of 4 and 16 inch (0.1 and 0.4 m), may be 0.35 and 0.09 psi per ft ( 8 and 2 kPa per m) of pipeline, respectively. Several pumps in series are therefore required also for moderate transportation distances. The results indicate that centrifugal pumps can be a cost-effective alternative for handling and transportation of sediments at a low water content.
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