Solution of the equation of transfer for interlocked multiplets with planck function as a nonlinear function of optical depth     

S. Karanjai  T. K. Deb 《Astrophysics and Space Science》1991,184(1):57-63

The equation of transfer for interlocked multiplets has been solved exactly by the method used by Busbridge and Stibbs (1954) for exponential form of the Planck functionB _v (T)=b ₀+b ₁ e ^–.  相似文献   

Fe sorption onto nontronite (NAu-2)     

Deb P. Jaisi  Chongxuan Liu  Ruth E. Blake 《Geochimica et cosmochimica acta》2008,72(22):5361-5371

The sorption of ferrous iron to a clay mineral, nontronite (NAu-2, a ferruginous smectite), was investigated under strictly anoxic conditions as a function of pH (3-10), Fe²⁺ concentration (0.01-50 mM), equilibration time (1-35 days), and ionic strength (0.01-0.5 M NaClO₄). The surface properties of NAu-2 were independently characterized to determine its fixed charge and amphoteric site density in order to interpret the Fe²⁺ sorption data. Fe²⁺ sorption to NAu-2 was strongly dependent on pH and ionic strength, reflecting the coupled effects of Fe²⁺ sorption through ion exchange and surface complexation reactions. Fe²⁺ sorption to NAu-2 increased with increasing pH from pH 2.5 to 4.5, remained constant from pH 4.5 to 7.0, increased again with further increase of pH from pH 7.0 to 8.5, and reached a maximum above pH 8.5. The Fe²⁺ sorption below pH 7.0 increased with decreasing ionic strength. The differences of Fe²⁺ sorption at different ionic strengths, however, diminished with increasing equilibration time. The Fe²⁺ sorption from pH 4.5 to 7.0 increased with increasing equilibration time up to 35 days and showed stronger kinetic behavior in higher ionic strength solutions. The kinetic uptake of Fe²⁺ onto NAu-2 is consistent with a surface precipitation mechanism although our measurements were not able to identify secondary precipitates. An equilibrium model that integrates ion exchange, surface complexation and aqueous speciation reactions reasonably well describes the Fe²⁺ sorption data as a function of pH, ionic strength, and Fe²⁺ concentration measured at 24 h of equilibration. Model calculations show that the species Fe(OH)⁺ was required to describe Fe²⁺ sorption above pH 8.0 satisfactorily. Overall, this study demonstrated that Fe²⁺ sorption to NAu-2 is affected by complex equilibrium and kinetic processes, likely caused by surface precipitation reactions.  相似文献   

Response of multilayer geosynthetic-reinforced bed resting on soft soil with stone columns   总被引：2，自引：0，他引：2  

Kousik Deb  Sarvesh Chandra  P.K. Basudhar   《Computers and Geotechnics》2008,35(3):323-330

In the present study, a mechanical model has been developed to study the behavior of multilayer geosynthetic-reinforced granular fill over stone column-reinforced soft soil. The granular fill and geosynthetic reinforcement layers have been idealized by Pasternak shear layer and rough elastic membranes, respectively. The Kelvin–Voight model has been used to represent the time-dependent behavior of saturated soft soil. The stone columns are idealized by stiffer springs and assumed to be linearly elastic. The nonlinear behavior of the soft soil and granular fill is considered. The effect of consolidation of soft soil due to inclusion of the stone columns on settlement response has also been included in the model. Plane strain conditions are considered for the loading and reinforced foundation soil system. An iterative finite difference scheme is applied for obtaining the solution and results are presented in nondimensional form. It has been observed that if the soft soil is improved with stone columns, the multilayer reinforcement system is less effective as compared to single layer reinforcement to reduce the total settlement as there is considerable reduction in the total settlement due to stone column itself. Multilayer reinforcement system is effective for reducing the total settlement when stone columns are not used. However, multilayer reinforcement system is effective to transfer the stress from soil to stone column. The differential settlement is also slightly reduced due to application of multiple geosynthetic layers as compared to the single layer reinforcement system.  相似文献   

Impact of assimilation of INSAT-3D retrieved atmospheric motion vectors on short-range forecast of summer monsoon 2014 over the South Asian region     

Prashant?KumarEmail author  Sanjib?K.?Deb  C.?M.?Kishtawal  P.?K.?Pal 《Theoretical and Applied Climatology》2017,128(3-4):575-586

The Weather Research and Forecasting (WRF) model and its three-dimensional variational data assimilation system are used in this study to assimilate the INSAT-3D, a recently launched Indian geostationary meteorological satellite derived from atmospheric motion vectors (AMVs) over the South Asian region during peak Indian summer monsoon month (i.e., July 2014). A total of four experiments were performed daily with and without assimilation of INSAT-3D-derived AMVs and the other AMVs available through Global Telecommunication System (GTS) for the entire month of July 2014. Before assimilating these newly derived INSAT-3D AMVs in the numerical model, a preliminary evaluation of these AMVs is performed with National Centers for Environmental Prediction (NCEP) final model analyses. The preliminary validation results show that root-mean-square vector difference (RMSVD) for INSAT-3D AMVs is ～3.95, 6.66, and 5.65 ms^?1 at low, mid, and high levels, respectively, and slightly more RMSVDs are noticed in GTS AMVs (～4.0, 8.01, and 6.43 ms^?1 at low, mid, and high levels, respectively). The assimilation of AMVs has improved the WRF model of produced wind speed, temperature, and moisture analyses as well as subsequent model forecasts over the Indian Ocean, Arabian Sea, Australia, and South Africa. Slightly more improvements are noticed in the experiment where only the INSAT-3D AMVs are assimilated compared to the experiment where only GTS AMVs are assimilated. The results also show improvement in rainfall predictions over the Indian region after AMV assimilation. Overall, the assimilation of INSAT-3D AMVs improved the WRF model short-range predictions over the South Asian region as compared to control experiments.  相似文献   

Structural geometry of the early Precambrian terrane south of Coimbatore in the “Palghat Gap”, southern India     

K. Naha  R. Srinivasan  G. K. Deb 《Journal of Earth System Science》1997,106(4):237-247

The ENE-plunging macroscopic folds, traced by calc gneiss interbanded with marble and sillimanite schist within the Peninsular Gneiss around Suganapuram in the ‘Palghat gap’ in southern India, represent structures of the second generation (D₂). They have folded the axial planes of a set of D₁ isoclinal folds on stratification coaxially, so that the mesoscopic D₁ folds range from reclined in the hinge zones, through inclined to upright in the limb zones of the D₂ folds. Orthogonal relation between stratification and axial planar cleavage, and ‘M’ shaped folds on layering locate the hinge zones of the D₁ folds, whereas folds on axial planar cleavage with ‘M’ shaped folds are the sites of the D₂ fold hinges. Extreme variation in the shapes of the isoclinal D₁ folds from class 1B through class 1C to nearly class 2 of Ramsay is a consequence of buckling followed by flattening on layers of widely varying viscosity contrast. The large ENE-trending structures in this supracrustal belt within the Peninsular Gneiss in the ‘Palghat gap’ could not have evolved by reorientation of NS-trending structures of the Dharwar tectonic province to the north by movement along the Moyar-Bhavani shear zone which marks the boundary between the two provinces. This is because the Moyar and Bhavani faults are steep dipping reverse faults with dominant dip-slip component. Deceased  相似文献   

Petrology, geothermobarometry and C-O-H-S fluid compositions in the environs of Rampura-Agucha Zn-(Pb) ore deposit, Bhilwara District, Rajasthan     

M. Deb  Uma Sehgal 《Journal of Earth System Science》1997,106(4):343-356

The massive Zn-(Pb) sulfide ore body at Rampura-Agucha in Bhilwara district, Rajasthan, occurs within graphitic metapelites surrounded by garnet-biotite-sillimanite gneiss containing concordant bodies of amphibolite. These rocks and the sulfide ores have been studied to estimate the pressure, temperature and fluid composition associated with upper amphibolite facies metamorphism. Geothermobarometric calculations involving garnet-biotite and garnet-hornblende pairs, as well as sphalerite-hexagonal pyrrhotite-pyrite and garnet-plagioclase-sillimanite-quartz assemblages indicate that the most pervasive P-T condition during peak of regional metamorphism was 650°C and 6 kb, and was attained between the first and second deformations in the region. Some temperature-pressure estimates also cluster around 500°C–5.1 kb which probably represent retrograde cooling during unloading. Consideration of devolatilization equilibria in the C-O-H-S system at the pervasive metamorphic conditions mentioned above shows that the metamorphic fluid was H₂O-rich ( ) but also had a substantial component of . and were the other important phases in the fluid. CO (X_CO = 0.002) and were the minor phases in the fluid. It is probable that a part of this aqueous fluid was consumed by re-/neocrystallization of hydrous silicate phases like chlorite during the retrogressive metamorphic path, so that fluid entrapped in quartz below 450°C was rendered CO₂-rich (Holleret al 1996).  相似文献   

Water policy,trust and governance in the Murray-Darling Basin     

Margaret Alston  Kerri Whittenbury  Deb Western  Aaron Gosling 《The Australian geographer》2016,47(1):49-64

Concerns for river health in the Murray-Darling Basin (MDB) area and shifting priorities for water use have led to a significant process of water reform over the last decade. The MDB area, also known as the food bowl of Australia, produces much of the country's food and is home to a significant portion of the population. A long-term drought, historical over-allocation of water for irrigation and climate variability have led to mounting concerns about the long-term viability of the rivers. While the reform process has resulted in the Commonwealth government taking control of the rivers from the States, it has also been influenced by changes in governments and consequent shifts in water allocation priorities from a privileging of agriculture to a broader approach encompassing economic, environmental and social concerns. This had led to uncertainty for the people and communities in the Basin and some confusion between the various layers of governance structures. This paper presents the results of exploratory research conducted with key, high-level stakeholders involved in water reform to examine their perceptions of the evolving water policy process. Despite agreement amongst stakeholders that returning water to the environment to ensure river health is critical, our research reveals significant tensions between stakeholders concerning the evolving process, particularly centred on the potential social outcomes and fairness and equity. This suggests the need for more integrated and transparent governance structures, attention to levels of trust between partners and a common vision that incorporates environmental, economic and social goals.  相似文献   

Simultaneous monitoring of soil 222Rn in the Eastern Himalayas and the geothermal region of eastern India: an earthquake precursor     

Chowdhury  Saheli  Deb  Argha  Barman  Chiranjib  Nurujjaman  Md.  Bora  Dipok K. 《Natural Hazards》2022,112(2):1477-1502

Natural Hazards - Activity of 222Rn gas in soil has been recorded continuously at three monitoring centres, namely Ravangla and Diphu in the Eastern Himalayan region and Tantloi in the geothermal...  相似文献   

Concentration of polybrominated diphenyl ethers (PBDEs) in sediment cores of Sundarban mangrove wetland, northeastern part of Bay of Bengal (India)   总被引：4，自引：0，他引：4  

Binelli A  Sarkar SK  Chatterjee M  Riva C  Parolini M  Bhattacharya BD  Bhattacharya AK  Satpathy KK 《Marine pollution bulletin》2007,54(8):1220-1229

The paper presents the first comprehensive survey of congener profiles (12 congeners) of polybrominated diphenyl ethers (PBDEs) in core sediment samples (<63 microm) covering seven sites in Sundarban mangrove wetland (India). Gas-chromatographic analyses were carried out in GC-Ms/Ms for tri- to hepta- brominated congeners. Results pointed out a non-homogenous contamination of the wetland with summation operator(12) PBDE values ranging from 0.08 to 29.03 ngg(-1), reflecting moderate to low contamination closely in conformity to other Asian aquatic environments. The general order of decreasing congener contribution to the total load was: BDE 47>99>100>154, similar to the distribution pattern worldwide. Although tetrabromodiphenyl ether BDE 47 was found in all samples followed by hexabromodiphenyl ether BDE-154, they were not necessarily the dominant congeners. No uniform temporal trend on PBDE levels was recorded probably due to particular hydrological characteristics of the wetland and/on non-homologous inputs from point sources (untreated municipal wastewater and local industries, electronic wastes from the dump sites, etc.) of these compounds. Because of the propensity of PBDEs to accumulate in various compartments of wildlife and human food webs, evaluation of biological tissues should be undertaken as a high priority.  相似文献   

Axi-symmetric Analysis of Geosynthetic-reinforced Granular Fill-soft Soil System with Group of Stone Columns   总被引：1，自引：1，他引：0  

Kousik Deb  P. K. Basudhar  S. Chandra 《Geotechnical and Geological Engineering》2010,28(2):177-186

The paper presents a mechanical model to predict the behavior of geosynthetic-reinforced granular fill resting over soft soil improved with group of stone columns subjected to circular or axi-symmetric loading. The saturated soft soil has been idealized by spring-dashpot system. Pasternak shear layer and rough elastic membrane represent the granular fill and geosynthetic reinforcement layer, respectively. The stone columns are idealized by stiffer springs. The nonlinear behavior of granular fill and soft soil is considered. Consolidation of the soft soil due to inclusion of stone columns has also been included in the model. The results obtained by using the present model when compared with the reported results obtained from laboratory model tests shows very good agreement. The effectiveness of geosynthetic reinforcement to reduce the maximum and differential settlement and transfer the stress from soft soil to stone columns is highlighted. It is observed that the reduction of settlement and stress transfer process are greatly influenced by stiffness and spacing of the stone columns. It has been further observed that for both geosynthetic-reinforced and unreinforced cases, the maximum settlement does not change if the ratio between spacing and diameter of stone columns is greater than 4.  相似文献