A study on the optimization of the arrangement of flotation circuits     

D.N. Sutherland 《International Journal of Mineral Processing》1981,7(4):319-346

The optimum utilization of available plant capacity has been investigated by simulation of a three-stage flotation circuit. By using simple models of the flotation process a wide variety of cell arrangements has been investigated and the findings tested against a number of operating flotation plants. It is concluded that the efficiency of operation of flotation systems is rather insensitive to circuit arrangement unless the circuit becomes grossly unbalanced. Circuit performance is much more sensitive to the flotation conditions and selectivity in the banks and it is only if a new circuit configuration leads to significantly improved flotation conditions that real improvements are likely. Simulation studies would require detailed modelling of such effects to be useful for circuit optimization studies.  相似文献   

Channel morphology and bedload pulses in braided rivers: a laboratory study     

Trevor B. Hoey  Alex J. Sutherland 《地球表面变化过程与地形》1991,16(5):447-462

Bedload pulses in gravel-bed rivers have been widely reported in recent years and attempts have been made to relate them to channel morphology. Bedload transport and channel morphology were measured in a small-scale generic model of braided gravel-bed streams. Two experiments are described in which braided channels developed in a 14 m × 3 m sand tray. Total bedload output from the tray was weighed every 15 minutes. Stream bed geometry was surveyed every four hours. Pulses were observed in the bedload output time series, and were qualitatively related to the channel morphology immediately upstream of the measuring section. The Bagnold (1980) bedload equation generally overpredicts measured bedload transport rates when applied to channels that were in equilibrium or aggrading. Underprediction occurred when applied to degrading channels. Aggradation was associated with channel multiplication and bar deposition. Channel pattern simplification occurred when degradation took place, and bars emerged from the water flow. Development of phases of aggradation and degradation is dependent upon the three-dimensional geometry of the stream beds. Spatial and temporal feedback loops can be identified, enabling links between channel morphology and bedload transport rate to be directly identified.  相似文献   

Resistance to flow past deformable boundaries     

T. R. Davies  A. J. Sutherland 《地球表面变化过程与地形》1980,5(2):175-179

An hypothesis from which a general principle covering deformation of alluvial boundaries may be developed is proposed, namely—flow of fluid past a deformable boundary will deform the boundary so as to increase the resistance to flow. Upon attainment of a local maximum of resistance to flow the boundary shape will cease to change. Evidence from channel bed forms, meander geometry and armoured beds is presented to support the hypothesis. One implication of the hypothesis is that channels will adjust so that sediment movement is maximized. The authors would like geomorphologists to test this in their work on landscape evolution.  相似文献   

Neutrino-pair bremsstrahlung in collisions between neutrons and nuclei in neutron star matter     

Elliott G. Flowers  Peter G. Sutherland 《Astrophysics and Space Science》1977,48(1):159-164

In neutron star matter over the density range 4.3×10¹¹<-ϱ≤4×10¹⁴ g cm⁻³ there are both free neutrons and neutron-rich nuclei. If there is a weak neutral current interaction between neutrinos and neutrons, as suggested by recent experiments, then when neutrons scatter off nuclei they may emit pairs as bremsstrahlung radiation. We calculate the associated emissivity for degenerate (but not superfluid) neutrons and uncorrelated (not crystallized) nuclei. We find that, under these conditions. this emissivity can under some conditions compare with that calculated by Festa and Ruderman for bremsstrahlung in electron-nucleus collisions.  相似文献   

In-the-field politics: Multiple voices of outworkers and researcher     

Elissa Sutherland 《The Australian geographer》2004,35(2):161-168

In this paper I reflect on some key methodological tensions that emerged during my PhD research. The research critically analyses the political struggles of outworking¹ women from Chinese, Vietnamese and Cambodian backgrounds in Sydney, Australia, for minimum wages and a monitoring of ethical networks in the clothing industry from 1997 to 2002. Rather than present 'key findings' in this paper I instead reveal how I began to think more critically and in less absolute ways about reading the multiple voices of outworkers, NGO workers and my own voice as researcher, activist and English teacher. I drew insights from Bakhtin's dialogism for thinking about research as shaped by sets of conversations. In this paper I reflect on several 'in-the-field' interactions: organising interviews, interviewing outworkers through an interpreter, storytelling in a rights-based English class setting, and how I and other participants represented outworking women in different forums. Dialogism required I take seriously the concept that knowledges are socially constructed in very particular contexts and this led to a rejection of my earlier notion of a singular authentic voice for outworking women or for me as researcher.  相似文献   

The Abiotic Nitrite Oxidation by Ligand-Bound Manganese (III): The Chemical Mechanism     

Luther III  George W.  Karolewski  Jennifer S.  Sutherland  Kevin M.  Hansel  Colleen M.  Wankel  Scott D. 《Aquatic Geochemistry》2021,27(3):207-220

Aquatic Geochemistry - Given their environmental abundances, it has been long hypothesized that geochemical interactions between reactive forms of manganese and nitrogen may play important roles in...  相似文献   

Cross-equatorial flow of grounded abyssal ocean currents     

Alexander Kim  Bruce R. Sutherland 《地球物理与天体物理流体动力学》2014,108(4):363-386

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Channel responses to varying sediment input: A flume experiment modeled after Redwood Creek, California   总被引：1，自引：0，他引：1  

Mary Ann Madej  Diane G. Sutherland  Thomas E. Lisle  Bonnie Pryor   《Geomorphology》2009,103(4):507-519

At the reach scale, a channel adjusts to sediment supply and flow through mutual interactions among channel form, bed particle size, and flow dynamics that govern river bed mobility. Sediment can impair the beneficial uses of a river, but the timescales for studying recovery following high sediment loading in the field setting make flume experiments appealing. We use a flume experiment, coupled with field measurements in a gravel-bed river, to explore sediment transport, storage, and mobility relations under various sediment supply conditions. Our flume experiment modeled adjustments of channel morphology, slope, and armoring in a gravel-bed channel. Under moderate sediment increases, channel bed elevation increased and sediment output increased, but channel planform remained similar to pre-feed conditions. During the following degradational cycle, most of the excess sediment was evacuated from the flume and the bed became armored. Under high sediment feed, channel bed elevation increased, the bed became smoother, mid-channel bars and bedload sheets formed, and water surface slope increased. Concurrently, output increased and became more poorly sorted. During the last degradational cycle, the channel became armored and channel incision ceased before all excess sediment was removed. Selective transport of finer material was evident throughout the aggradational cycles and became more pronounced during degradational cycles as the bed became armored. Our flume results of changes in bed elevation, sediment storage, channel morphology, and bed texture parallel those from field surveys of Redwood Creek, northern California, which has exhibited channel bed degradation for 30 years following a large aggradation event in the 1970s. The flume experiment suggested that channel recovery in terms of reestablishing a specific morphology may not occur, but the channel may return to a state of balancing sediment supply and transport capacity.  相似文献   

Searching for periodicities in the MACHO light curve of LMC X-2     

C. Alcock  R. A. Allsman  D. R. Alves  T. S. Axelrod  A. C. Becker  D. P. Bennett  P. A. Charles  K. H. Cook  A. J. Drake  K. C. Freeman  M. Geha  K. Griest  P. Groot  †  M. J. Lehner  S. L. Marshall  K. E. McGowan  ‡  D. Minniti  C. A. Nelson  B. A. Peterson  P. Popowski  M. R. Pratt  P. J. Quinn  W. Sutherland  A. B. Tomaney  T. Vandehei  J. van Paradijs 《Monthly notices of the Royal Astronomical Society》2000,316(4):729-733

Using the exceptional long-term monitoring capabilities of the MACHO project, we present here the optical history of LMC X-2 for a continuous 6-yr period. These data were used to investigate the previously claimed periodicities for this source of 8.15 h and 12.54 d: we find upper limits of 0.10 mag and 0.09 mag, respectively.  相似文献   

The power spectrum of the Point Source Catalogue redshift survey     

W. Sutherland  H. Tadros  G. Efstathiou  C. S. Frenk  O. Keeble  S. Maddox  R. G. McMahon  S. Oliver  M. Rowan-Robinson  W. Saunders  S. D. M. White 《Monthly notices of the Royal Astronomical Society》1999,308(2):289-301

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