Cr-spinel/olivine and Cr-spinel/liquid nickel partition coefficients from natural samples     

Chusi Li  Edward M. Ripley  Edmond A. Mathez 《Geochimica et cosmochimica acta》2008,72(6):1678-1684

The Nernst partition coefficient of nickel (D^Ni) between Cr-spinel and silicate melt in natural systems has been investigated using mid-ocean ridge basalts (MORB) and other volcanic rocks. The Cr-spinel/olivine D^Ni values in volcanic rocks are between 1.2 and 0.3, indicating that the Cr-spinel/liquid D^Ni values vary from slightly higher to significantly lower than the olivine/liquid D^Ni values in natural systems. The Cr-spinel/liquid D^Ni values from the MORB samples vary between 6 and 11, slightly higher than those from the S-bearing experiments of Satari et al. [Satari P., Brenan J. M., Horn I. and McDonough W. F. (2002) Experimental constraints on the sulfide- and chromite-silicate melt partitioning behavior of rhenium and platinum-group elements. Economic Geology97, 385-398]. The results of the MORB samples and the experiments of Satari et al. (2002) indicate a negative correlation between the Cr-spinel/liquid D^Ni and the X_Cr values in Cr-spinels (Cr cation number on the basis of 3 total cations in the spinel structure). Variations of Cr-spinel/liquid D^Ni values with Cr-spinel compositions can be estimated from an empirical equation based on the results of the MORB samples and the experiments by Satari et al. (2002). The choice of Cr-spinel/liquid D^Ni = 10 for numerical modeling by Righter et al. [Righter K., Leeman W. P. and Hervig R. L. (2006) Partitioning of Ni, Co, and V between spinel-structured oxides and silicate melts: importance of spinel composition. Chemical Geology227, 1-25] is reasonable for basaltic systems. For picritic and komatiitic systems a lower value of ∼5 is more appropriate.  相似文献   

Carbon Isotope Geochemistry of the Orinoco Basin     

F. C. Tan  J. M. Edmond 《Estuarine, Coastal and Shelf Science》1993,36(6)

Stable carbon isotope ratios have been used to study the sources of particulate organic carbon (POC) and total dissolved inorganic carbon in the Orinoco Basin. The isotopic composition of total dissolved inorganic carbon shows a range of from -8·1 to -23·0 ppt, an indication of dominance of biological processes. The isotopic composition of POC exhibits a range of from -24·1 to -34·6 ppt with little seasonal variation. The isotopic evidence indicates that the POC is predominantly of terrestrial origin rather than a result of in situ planktonic production. The similarity of isotopic composition of POC and coastal sediments suggests that riverine organic detritus has been transported 30-50 km offshore in a direction parallel to the Orinoco river channel.  相似文献   

Effect of shallow and narrow water on added mass of cylinders with various cross-sectional shapes     

Z.X. Zhou  Edmond Y.M. Lo  S.K. Tan 《Ocean Engineering》2005,32(10):1199-1215

The sway, heave and roll added masses of three uniform cylinders with semi-circular, rectangular and triangular cross-sectional shapes in shallow and narrow water are numerically analysed. The method is based on simulation of the potential flow induced by the cylinder's mode of motion. The effects of shallow and narrow water on added mass are analysed and presented. It is concluded that the shallow and narrow water effects on added mass depend on the different cross-section shapes of the cylinders. In particular, the water depth effect on sway added mass is stronger than that on heave added mass while the narrow water effect on sway is weaker than that on heave. The shallow water effect on added mass tends to weaken the narrow water effect. Lastly the effect of shallow and narrow water on added mass on a rectangular cylinder is the strongest while that on a triangular cylinder is the weakest.  相似文献   

Analysis of infrared photometry of algol     

Ishmael M. Murad  Edwin Budding 《Astrophysics and Space Science》1984,98(1):163-169

Infrared (JHKLM) photometry of Per, due to Zeilik (1980), has been analysed by computer-based optimization methods. The data have been used primarily to find empirical mean flux ratios at known IR wavelengths for the two photospheres of the eclipsing pair. These flux ratios have then been compared with values predicted by various model atmosphere calculations. The ratio of effective temperatures can be given asT _B/T _A=0.42±0.02, but there remains some small discrepancy between the empirical results and model calculations at the longest wavelengths (KLM). The possibility of IR-excess at longer wavelengths is considered, but the evidence is marginal.  相似文献   

Creating a GIS application for retail centers in Jeddah city   总被引：2，自引：0，他引：2  

AbdulKader A. Murad   《International Journal of Applied Earth Observation and Geoinformation》2003,4(4):329-338

The aim of this paper is to identify the role of geographical information systems (GIS) in supporting retail planners in monitoring and analyzing retail development and growth. At first, a review about retail planning and its relevant issues is made. Second, GIS is defined together with its applications in retail planning. The third part discusses the created GIS application that is designed for two retail centers in Jeddah city, Saudi Arabia. This application is created to help planners in defining the distribution of retail demand, describing customers profile, analyzing trade areas and modeling retail flows. Two useful models have been produced by this study. One is called market penetration and the other is based on spatial interaction technique. The former is created to examine retail center catchment area, while the latter is used to model the interaction between demand areas and retail centers.  相似文献   

An adjoint-based optimization method for gas production in shale reservoirs     

Antonio A. Novotny  Márcio A. Murad  Sidarta A. Lima 《Acta Geotechnica》2018,13(4):833-852

In this work, we consider a new model for flow in a multiporosity shale gas reservoir constructed within the framework of an upscaling procedure where hydraulic fractures are treated as (\(n-1\)) interfaces (\(n=2,3\)). Within this framework, the hydrodynamics is governed by a new pressure equation in the shale matrix which is treated as a homogenized porous medium composed of organic matter (kerogen aggregates with nanopores) and inorganic impermeable solid (clay, calcite, quartz) separated from each other by a network of interparticle pores of micrometer size. The solution of the pressure equation is strongly influenced by the constitutive response of the retardation parameter and effective hydraulic conductivity where the former incorporates gas adsorption/desorption in the nanopores of the kerogen. By focusing our analyses on this nonlinear diffusion equation in the domain occupied by the shale matrix, an optimization strategy seated on the adjoint sensitivity method is developed to minimize a cost functional related to gas production and net present value in a single hydraulic fracture. The gradient of the objective functional computed with the adjoint formulation is explored to update the controlled pressure drop aiming to optimize production in a given window of time. The combination of the direct approach and gradient-based optimization using the adjoint formulation leads to the construction of optimal production scenarios under controlled pressure decline in the well. Numerical simulations illustrate the potential of the methodology proposed herein in optimizing gas production.  相似文献   

Reproduction of the fiddler crabsUca longisignalis andUca spinicarpa in a Gulf of Mexico salt marsh     

Edmond C. Mouton  Darryl L. Felder 《Estuaries and Coasts》1995,18(3):469-481

Monthly field sampling of active animals in a Louisiana coastal salt marsh monitored changes in size class frequency distributions, ovarian development of females, and rates of egg extrusion for two species ofUca endemic to the Gulf of Mexico. Ovigerous females occurred no earlier than February forUca spinicarpa and April forUca longisignalis. Peak percentages of ovigerous females were observed in June 1992 forUca longisignalis (67%) and in March 1993 forUca spinicarpa (85%). Peaks in ash-free dry weight (AFDW, in g) of females coincide with peak periods of ovarian development and subsequent ovigery. Mean biomass as AFDW of males and females combined forUca longisignalis was 0.26 g individual^?1 and forUca spinicarpa was 0.17 g individual^?1. A significant correlation existed between AFDW and carapace width in both species, males and females.U. longisignalis appears to be of warm-temperate lineage, and its reproductive activity is the more seasonally restricted, with later ovarian development, earliest egg laying delayed to late spring, and peak ovigery in summer. In keeping with putative tropical affinities ofUca spinicarpa, ovarian development is episodic over a longer-period from late winter to summer, and eggs are produced earlier in the year. The more striking seasonality in reproductive activity and biomass peaks forUca longisignalis may also reflect some nutritional dependency on temperate, annual marsh plants that characterize its preferred habitats.  相似文献   

A comparison of single scattering and finite difference synthetic seismograms in realizations of 2-D elastic random media     

Richard T. Coates  Edmond E. Charrette 《Geophysical Journal International》1993,113(2):463-482

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Refinement of the Kudo-Weill plagioclase thermometer and its application to basaltic rocks   总被引：1，自引：0，他引：1  

Edmond A. Mathez 《Contributions to Mineralogy and Petrology》1973,41(1):61-72

The Kudo-Weill plagioclase thermometer is applied to basaltic rocks. Comparison of measured and calculated crystallization temperatures shows that the latter are generally higher than measured values. The plagioclase thermometer predicts non-ideal behavoir of plagioclase solid solution and is in close agreement with experimental work at lower temperature. New equations are generated that relate plagioclase and melt chemistries to plagioclase crystallization temperatures; and these, combined with activity coefficient corrections, result in a refinement of the plagioclase thermometer.  相似文献   

Chemical oceanography vols 5 and 6: edited by J. P. Riley and R. Chester. Academic Press, 1976, £13.50 and £14.00 respectively     

J.M. Edmond 《Geochimica et cosmochimica acta》1979,43(11):1869-1870

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