A Variable Mesh Spacing for Large-Eddy Simulation Models in the Convective Boundary Layer     

Gervásio Annes Degrazia  Umberto Rizza  Franciano Scremin Puhales  Antônio Gledson Goulart  Jonas Carvalho  Guilherme Sausen Welter  Edson Pereira Marques Filho 《Boundary-Layer Meteorology》2009,131(2):277-292

A variable vertical mesh spacing for large-eddy simulation (LES) models in a convective boundary layer (CBL) is proposed. The argument is based on the fact that in the vertical direction the turbulence near the surface in a CBL is inhomogeneous and therefore the subfilter-scale effects depend on the relative location between the spectral peak of the vertical velocity and the filter cut-off wavelength. From the physical point of view, this lack of homogeneity makes the vertical mesh spacing the principal length scale and, as a consequence, the LES filter cut-off wavenumber is expressed in terms of this characteristic length scale. Assuming that the inertial subrange initial frequency is equal to the LES filter cut-off frequency and employing fitting expressions that describe the observed convective turbulent energy one-dimensional spectra, it is feasible to derive a relation to calculate the variable vertical mesh spacing. The incorporation of this variable vertical grid within a LES model shows that both the mean quantities (and their gradients) and the turbulent statistics quantities are well described near to the ground level, where the LES predictions are known to be a challenging task.  相似文献   

Plasmid profile and curing analysis of Pseudomonas aeruginosa as metal resistant     

C. Edward Raja M.Sc.  G. S. Selvam M.Sc.  M. Phil.  Ph.D. 《International Journal of Environmental Science and Technology》2009,6(2):259-266

The isolate Pseudomonas aeruginosa exhibited resistance to heavy metals such as cadmium, chromium, nickel and lead. Plasmid DNA was isolated from P. aeruginosa and designated as pBC15. The size of the plasmid DNA was approximately 23 kb. Escherichia coli DH5α was transformed with plasmid pBC15 subsequired resistance to nickel and ampicillin. The same size of the plasmid was isolated from E. coli transformant and separated on 0.7 % agarose gel electrophoresis. The restriction analysis of pBC15 showed that the plasmid DNA has single site for Bam HI and Eco RI and three sites for Xho I which were compared with 1 Kb DNA and λ Hind III digest molecular markers. Therefore, the size of the plasmid DNA of pBC15 was confirmed to be 23 kb. Curing was carried out by ethidium bromide, acridine orange, novobiocin, sodium dodechyl sulphate and elevated temperature (40 °C). Transformation and curing results suggest that nickel and ampicillin resistance gene was conferred by plasmid DNA. Cadmium resistant gene was present on chromosomal DNA along with the gene for chromium resistance. Lead resistance gene was shown to be present on the chromosomal DNA rather than the plasmid DNA as the cured and uncured cultures remained similar in lead resistance. Therefore, the ability of P. aeruginosa resistant to nickel and ampicillin is plasmid mediated and transferable to other strains whereas cadmium, chromium and lead could be chromosomal encoded. The heavy metal and antibiotic resistances of P. aeruginosa can be used to exploit for clean up industrial wastewater and bioremediation of heavy metal contaminated soil.  相似文献   

The Palaeomagnetism of some Scottish Tertiary Dykes and their Baked Contacts     

P. K. S. Raja 《Geophysical Journal International》1964,9(1):15-19

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Ductility of reinforced concrete sections with confined compression zones     

Prakash Desayi  K. T. Raja Sundara Iyengar  K. Nagi Reddy 《地震工程与结构动力学》1975,4(2):111-118

Confinement of concrete in circular spiral steel binders imparts to it considerable ductility and also some increase in strength. This property can be utilized in designing concrete structures to withstand seismic forces where the members are required to possess not only strength but also energy absorbing capacity. Assuming the stress-strain behaviour of confined concrete as elastic-plastic, the ductility factor for strain and the strength factor (denoting increase in strength) have been determined for concrete confined to different degrees. Similarly, assuming the moment-curvature behaviour of reinforced concrete sections with confined compression concrete to be elastic-plastic, the ductility factor for curvature has been determined for such beams. The computed moment-curvature plots have been found to compare satisfactorily with tests on 18 beams. Ductility factors for curvature of singly and doubly reinforced concrete sections with compression concrete confined to different degrees have been determined and presented for certain typical cases. Such plots would be of use in designing reinforced concrete beam sections for required ductility.  相似文献   

A palaeomagnetic study of lower Proterozoic granites from Western Kenya     

J. P. Patel  P. K. S. Raja 《Geophysical Journal International》1979,58(2):279-286

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Linkage between rainfall singularities and geomagnetic activity     

R. S. Reddy  K. S. Raja Rao  Bh. V. Ramana Murty 《Meteorology and Atmospheric Physics》1984,33(2-3):127-142

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Heavy metal concentrations in shallow marine sediments affected by submarine tailings disposal and artisanal gold mining,Buyat-Ratototok district,North Sulawesi,Indonesia     

Evan N. Edinger  P. Raja Siregar  George M. Blackwood 《Environmental Geology》2007,52(4):701-714

Trace element concentrations in shallow marine sediments of the Buyat-Ratototok district of North Sulawesi, Indonesia, are affected by submarine disposal of industrial gold mine tailings and unregulated dumping of tailings and wastewater from small-scale gold mining using mercury amalgamation. Industrial mine tailings contained 590–690 ppm arsenic, 490–580 ppm antimony, and 0.8–5.8 ppm mercury. Tailings-affected sediment As and Sb concentrations were 20–30 times higher than in muddy sediments not contaminated with tailings, and 50–60 times higher than pre-mining average. Highest mercury concentrations were observed in sediments affected by small-scale mining using mercury amalgamation (5–29 ppm). Concentrations of most other trace elements were comparable in sediments affected by both types of mining and were slightly higher than regional averages for sediments collected before the onset of industrial mining. Elevated concentrations of both As and Sb in approximately equal proportions suggest tailings dispersal of at least 3.5 km. Mercury released from artisanal gold mining dispersed up to 4 km from river mouths. Slight increases in concentrations of non-mercury trace elements in areas affected by artisanal mining over pre-industrial mining concentrations were probably caused by increased rates of erosion. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.  相似文献   

How chalcophile is rhenium? An experimental study of the solubility of Re in sulphide mattes     

Raúl O.C. Fonseca  Guilherme Mallmann  Hugh St.C.O''Neill  Ian H. Campbell 《Earth and Planetary Science Letters》2007,260(3-4):537-548

Although the Re/Os isotopic system has proved to be a valuable aid in understanding the evolution of the Earth's mantle, interpretation of the data is currently hindered by limited knowledge of the high-temperature geochemical behaviour of Re. In particular, the extent to which Re in the mantle is hosted by sulphide or silicate phases is poorly known. We report the results of an experimental study of the solubility of Re in sulphide melts (called here “mattes”) coexisting with a Re-rich Re–Fe alloy in the system Fe–Re–S–O over a range of fO₂, fS₂ and temperatures, which allow extrapolation to conditions pertinent to the Earth's mantle. The solubility of Re in mattes increases with increasing fS₂, with Re dissolving as Re⁴⁺ at high fS₂ and Re⁰ at low fS₂. The effect of fO₂ is negligible except at high fO₂ where O in the matte becomes important. At constant fS₂, an increase in temperature leads to an increase in the solubility of Re⁰ in the matte, but a decrease in the solubility of Re⁴⁺. These results, coupled with data for the Re solubility in silicate melts taken from the literature, allow the calculation of Re matte/silicate–melt partition coefficients (D_Re^matte/sil) for a range of conditions. The calculated D_Re^matte/sil show a large dependence on fO₂, and a lesser dependency on fS₂, with Re behaving as a chalcophile element for relatively reduced MORB-type mantle and as a lithophile element for the oxidised sources of island-arc basalts. The sensitivity of Re to fS₂ and fO₂ reconciles the apparent discrepancies between previous estimates of this parameter, which can vary by more than five orders of magnitude within the range of fS₂ and fO₂ covered by terrestrial basaltic magmas.  相似文献   

The effect of oxygen fugacity on the partitioning of Re between crystals and silicate melt during mantle melting   总被引：1，自引：0，他引：1  

Guilherme Mallmann  Hugh St.C. O’Neill 《Geochimica et cosmochimica acta》2007,71(11):2837-2857

Interpretation of Re-Os isotopic systematics applied to mantle and mantle-derived rocks is currently hindered by the poorly understood behaviour of Re and Os during partial melting. Of particular interest is the incompatibility of Re and how it partitions between melt and the different mantle phases. Here, we study the partitioning behaviour of Re between the common upper mantle minerals (garnet, spinel, clinopyroxene, orthopyroxene, and olivine) and silicate melt under temperature (1275-1450 °C) and pressure (1.5-3.2 GPa) conditions relevant for basaltic magma genesis, over a range of oxygen fugacity (?O₂) large enough (QFM+5.6 to QFM−2.9) to demonstrate the effects of changing the oxidation state of Re from 4+ to 6+. Rhenium crystal/silicate-melt partition coefficients vary by 4-5 orders of magnitude, from moderately compatible to highly incompatible, for pyroxenes, garnet, and spinel as the oxidation state of Re changes from 4+ to 6+, but Re in either oxidation state is incompatible in olivine. Because the changeover from the one Re oxidation state to the other occurs over the range of ?O₂s pertinent to partial melting in the Earth’s mantle, bulk Re crystal/silicate-melt partition coefficients during mantle melting are also expected to vary significantly according to the oxidation state of the system. For instance, assuming QFM−0.7 and QFM+1.6 as average ?O₂ for mid-ocean ridge (MORBs) and island arc (IABs) basalts, respectively, a difference of at least one order of magnitude for bulk Re partition coefficients is expected (excluding any influence from a sulphide phase). Hence, Re is probably much more incompatible during the genesis of IABs compared to MORBs. Our results also demonstrate that Re⁴⁺ has a partitioning behaviour similar to Ti⁴⁺ rather than Yb, and is accordingly not a sensitive indicator of garnet in the source. The lower concentrations of Re observed in ocean island basalts (OIBs) compared to MORBs are therefore not a result of being generated deeper in the mantle where garnet is stable, leaving the hypothesis of late-stage loss of Re from OIB lavas by degassing as the most plausible explanation.  相似文献   

The Diamantina Monazite: A New Low‐Th Reference Material for Microanalysis          下载免费PDF全文

Guilherme O. Gonçalves  Cristiano Lana  Ricardo Scholz  Ian S. Buick  Axel Gerdes  Sandra L. Kamo  Fernando Corfu  Daniela Rubatto  Michael Wiedenbeck  Hermínio A. Nalini Jr.  Luiz Carlos A. Oliveira 《Geostandards and Geoanalytical Research》2018,42(1):25-47

Most monazite reference materials (RMs) for in situ U‐Pb geochronology are rich in Th; however, many hydrothermal ore deposits contain monazite that is low in trace element contents, including Th, U and Pb. Because of potential problems with matrix effects and the lack of appropriate matrix‐matched RMs, such variations can bias dating of hydrothermal deposits. In this paper, we describe a polycrystalline low‐U and low‐Th Diamantina monazite from the Espinhaço Range, SE Brazil. It has a U‐Pb ID‐TIMS weighted mean ²⁰⁷Pb^*/²³⁵U ratio of 0.62913 ± 0.00079, ²⁰⁶Pb^*/²³⁸U of 0.079861 ± 0.000088 and ²⁰⁷Pb^*/²⁰⁶Pb^* of 0.057130 ± 0.000031, yielding a weighted mean ²⁰⁶Pb^*/²³⁸U date of 495.26 ± 0.54 Ma (95% c.l.). In situ dates acquired with different methods (LA‐(Q, SF, MC)‐ICP‐MS and SIMS) are within uncertainty of the ID‐TIMS data. U‐Pb LA‐(Q, MC)‐ICP‐MS runs, using Diamantina as a primary RM, reproduced the ages of other established RMs within < 1% deviation. The LA‐MC‐ICP‐MS analyses yielded homogeneous Sm‐Nd isotopic compositions (¹⁴³Nd/¹⁴⁴Nd = 0.511427 ± 23, 2s; ¹⁴⁷Sm/¹⁴⁴Nd = 0.1177 ± 13, 2s) and εNd_(495 Ma) of ?18.7 ± 0.5 (2s). SIMS oxygen isotope determinations showed measurement reproducibility better than ± 0.3‰ (2s), confirming Diamantina's relative homogeneity at test portion masses below 1 ng.  相似文献