Geometallurgical Modeling at Olympic Dam Mine, South Australia     

Jeff B. Boisvert  Mario E. Rossi  Kathy Ehrig  Clayton V. Deutsch 《Mathematical Geosciences》2013,45(8):901-925

Modeling of geometallurgical variables is becoming increasingly important for improved management of mineral resources. Mineral processing circuits are complex and depend on the interaction of a large number of properties of the ore feed. At the Olympic Dam mine in South Australia, plant performance variables of interest include the recovery of Cu and U₃O₈, acid consumption, net recovery, drop weight index, and bond mill work index. There are an insufficient number of pilot plant trials (841) to consider direct three-dimensional spatial modeling for the entire deposit. The more extensively sampled head grades, mineral associations, grain sizes, and mineralogy variables are modeled and used to predict plant performance. A two-stage linear regression model of the available data is developed and provides a predictive model with correlations to the plant performance variables ranging from 0.65–0.90. There are a total of 204 variables that have sufficient sampling to be considered in this regression model. After developing the relationships between the 204 input variables and the six performance variables, the input variables are simulated with sequential Gaussian simulation and used to generate models of recovery of Cu and U₃O₈, acid consumption, net recovery, drop weight index, and bond mill work index. These final models are suitable for mine and plant optimization.  相似文献   

A working environment for digital planetary data processing and mapping using ISIS and GRASS GIS     

Alessandro Frigeri  Trent Hare  Markus Neteler  Angioletta Coradini  Costanzo Federico  Roberto Orosei 《Planetary and Space Science》2011,59(11-12):1265-1272

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Evaluating alternative future sea-level rise scenarios     

Christine C. Shepard  Vera N. Agostini  Ben Gilmer  Tashya Allen  Jeff Stone  William Brooks  Michael W. Beck 《Natural Hazards》2012,63(2):1223-1224

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Responding to Emerging Contaminant Impacts: Situational Management          下载免费PDF全文

Suthan S. Suthersan  John Horst  Ian Ross  Erica Kalve  Joseph Quinnan  Erika Houtz  Jeff Burdick 《Ground Water Monitoring & Remediation》2016,36(3):22-32

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Assessment of perfluorinated compounds (PFCs) in plasma of bottlenose dolphins from two southeast US estuarine areas: relationship with age, sex and geographic locations     

Fair PA  Houde M  Hulsey TC  Bossart GD  Adams J  Balthis L  Muir DC 《Marine pollution bulletin》2012,64(1):66-74

Plasma PFCs were measured in 157 bottlenose dolphins (Tursiops truncatus) sampled from two US southeast Atlantic sites (Charleston (CHS), SC and Indian River Lagoon (IRL), FL) during 2003-2005. ∑PFCs, perfluoroalkyl carboxylates (∑PFCAs), perfluoroalkyl sulfonates (∑PFSAs) and individual compounds were significantly higher in CHS dolphins for all age/sex categories compared to IRL dolphins. Highest ∑PFCs concentrations occurred in CHS juvenile dolphins (2340 ng/g w.w.); significantly higher than found in adults (1570 ng/g w.w. males; 1330 ng/g w.w. females). ∑PFCAs were much greater in CHS dolphins (≈ 21%) compared to IRL dolphins (≈ 7%); ∑PFSAs were 79% in CHS dolphins versus 93% in IRL dolphins. PFOS, the dominant compound, averaged 72% and 84%, respectively, in CHS and IRL dolphins. Decreasing PFC levels occurred with age on the bioaccumulation of PFCs in both sites. These observations suggest PFC accumulation in these two dolphin populations are influenced by site-specific exposures with significantly higher levels in CHS dolphins.  相似文献   

Heterogeneity in mycorrhizal inoculum potential of flood-deposited sediments     

Mary J. Harner  Jeff S. Piotrowski  Ylva Lekberg  Jack A. Stanford  Matthias C. Rillig 《Aquatic Sciences - Research Across Boundaries》2009,71(3):331-337

Riparian areas are diverse systems where flooding creates new sites for establishment of vegetation. Symbioses with soil microorganisms, such as mycorrhizal fungi, affect vascular plant growth and community composition. It is unknown, however, how mycorrhizal fungi are dispersed along rivers and what potential they have to inoculate roots of plants establishing on recently deposited sedimentary surfaces of flood plains. We measured AMF inocula in sediment deposited by an average spring flood along an expansive riverine flood plain in Montana, USA, to determine whether AMF inocula were present in sediments and what types of propagules (spores, hyphae, or colonized root fragments) contribute to AMF infectivity. Flood-deposited sediments contained sufficient inocula for AMF to colonize host plants (Sorghum sudanense) grown in a greenhouse, and both AMF hyphal lengths and spore densities were correlated with infectivity. Availability of mycorrhizal inocula, which is patchily distributed in this system, may lead to microsites that differ in ability to support establishment and growth of early-successional plants.  相似文献   

Thermal infrared video details multiscale groundwater discharge to surface water through macropores and peat pipes          下载免费PDF全文

Martin A. Briggs  Danielle K. Hare  David F. Boutt  Glorianna Davenport  John W. Lane 《水文研究》2016,30(14):2510-2511

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Flow–plant interactions at leaf,stem and shoot scales: drag,turbulence, and biomechanics     

Ismail Albayrak  Vladimir Nikora  Oliver Miler  Matthew T. O’Hare 《Aquatic Sciences - Research Across Boundaries》2014,76(2):269-294

Flow–plant interactions are experimentally investigated at leaf, stem, and shoot scales in an open-channel flume at a range of Reynolds numbers. The experiments included measurements of instantaneous drag forces acting on leaves, stems, and shoots of the common freshwater plant species Glyceria fluitans, complemented with velocity measurements, high-resolution video recordings, and biomechanical tests of leaf and stem properties. The analyses of bulk statistics, power spectral densities, transfer functions, and cross-correlations of measured velocities and drag forces revealed that flow characteristics, drag force, and plant biomechanical and morphological properties are strongly interconnected and scale-dependent. The plant element–flow interactions can be subdivided into two classes: (I) passive interactions when the drag variability is due to the time variability of the wetted and frontal areas and squared approach velocity (due to the large-scale turbulence); and (II) active interactions representing a range of element-specific instabilities that depend on the element flexural rigidity and morphology. Implications of experimental findings for plant biophysics and ecology are briefly discussed.  相似文献   

Evaluation of nearshore wave models in steep reef environments     

Mark Buckley  Ryan Lowe  Jeff Hansen 《Ocean Dynamics》2014,64(6):847-862

To provide coastal engineers and scientists with a quantitative evaluation of nearshore numerical wave models in reef environments, we review and compare three commonly used models with detailed laboratory observations. These models are the following: (1) SWASH (Simulating WAves till SHore) (Zijlema et al. 2011), a phase-resolving nonlinear shallow-water wave model with added nonhydrostatic terms; (2) SWAN (Simulating WAve Nearshore) (Booij et al. 1999), a phase-averaged spectral wave model; and (3) XBeach (Roelvink et al. 2009), a coupled phase-averaged spectral wave model (applied to modeling sea-swell waves) and a nonlinear shallow-water model (applied to modeling infragravity waves). A quantitative assessment was made of each model’s ability to predict sea-swell (SS) wave height, infragravity (IG) wave height, wave spectra, and wave setup ( \( \overline{\eta} \) ) at five locations across the laboratory fringing reef profile of Demirbilek et al. (2007). Simulations were performed with the “recommended” empirical coefficients as documented for each model, and then the key wave-breaking parameter for each model (α in SWASH and γ in both SWAN and XBeach) was optimized to most accurately reproduce the observations. SWASH, SWAN, and XBeach were found to be capable of predicting SS wave height variations across the steep fringing reef profile with reasonable accuracy using the default coefficients. Nevertheless, tuning of the key wave-breaking parameter improved the accuracy of each model’s predictions. SWASH and XBeach were also able to predict IG wave height and spectral transformation. Although SWAN was capable of modeling the SS wave height, in its current form, it was not capable of modeling the spectral transformation into lower frequencies, as evident in the underprediction of the low-frequency waves.  相似文献   

Two solution methods for dynamic game in reservoir operation     

Mehran Homayoun-far  Arman Ganji  Davar Khalili  Jeff Harris 《Advances in water resources》2010

During the last decade, a number of models have been developed to consider the conflict in dynamic reservoir operation. Most of these models are discrete dynamic models which are developed based on game theory. In this study, a continuous model of dynamic game and its corresponding solutions are developed for reservoir operation. Two solution methods are used to solve the model of continuous dynamic game, namely the Ricatti equations and collocation methods. The Ricatti equations method is a closed form solution, requiring less computational efforts compared with discrete models. The collocation solution method applies Newton's method or a quasi-Newton method to find the problem solution. These approaches are able to generate operating policies for dynamic reservoir operation. The Zayandeh-Rud river basin in central Iran is used as a case study and the results are compared with alternative water allocation models. The results show that the proposed solution methods are quite capable of providing appropriate reservoir operating policies, while requiring rather short computational times due to continuous formulation of state and decision variables. Reliability indices are used to compare the overall performance of the proposed models. Based on the results from this study, the collocation method leads to improved values of the reliability indices for total reservoir system and utility satisfaction of water users, compared to the Ricatti equations method. This is attributed to the flexible structure of the collocation model. When compared to alternative water allocation models, lower values of reliability indices are achieved by the collocation method.  相似文献