Two tilted cosmological models filled with disordered radiation of perfect fluid and heat conduction in presence of a bulk viscous fluid and magnetic field are investigated. To get determinate solution, it has been assumed that the universe is filled with disordered radiation together with A = (BC)n, where A, B, C are metric potentials and n is constant. The coefficient of bulk viscosity is assumed to be power function of mass density. It has been shown that tilted nature of the model is preserved due to magnetic field. The various physical and geometrical aspects of the models are discussed. The nature of the models in presence and absence of magnetic field and bulk viscosity are also discussed.
The Phenomenon of parametric interaction of compiled wave exhibits a vital role in nonlinear optics. Using the straight forward compiled mode theory, the lattice displacement plays the great role in the parametric amplification is analytically investigated in magnetized piezoelectric as well as non piezoelectric semiconductors. The origin of nonlinear interaction is taken to be in the second order optical susceptibility arising from the nonlinear induced current density and polarization through lattice displacement. The threshold value of the pump electric field (E0th), lattice displacement (u), effective non linear polarization (PEN) and efficiency of crystal cell are obtained for different situation of practical interest, i.e. (i) for piezoelectric coupling only (ii) for deformation potential coupling only, (iii) for both the couplings.
The analytical investigations reveal that piezoelectric and deformation potential coupling, wave number, scattering angle, carrier concentration and magnetic field strongly affect the polarization and cell efficiency and also lattice displacement. This study provides new means for construction of crystal cell and for diagnostics of semiconductors devices.
Qualitative performance of a two-stage amplifier, configured by cascading Darlington pair amplifier with CE amplifier is critically analyzed. As a rare feature, simultaneous enhancement of voltage and current gains with enlarged bandwidth is observed. This proposed two-stage amplifier may be quite useful for amplification of small signals of mili-volts range and suitable for various analog electronics and communication applications.
The Lumshnong area of Jaintia Hills of Meghalaya is stratigraphically most significant due to the occurrences of the Sylhet and Kopili Formations which are considered as the most complete Palaeocene-Eocene sequence. The Sylhet Formation consists of six alternating limestone and sandstone members. The three Limestone Members (viz. Lakadong Limestone, Umlatdoh Limestone and Prang Limestone) of the Sylhet Formation are rich in benthonic cainozoic foraminifera. The Palaeocene-Eocene age is assigned in Sylhet Formation from the study of the foraminiferal fossil assemblages. From the study, it is also found that the sediments were deposited under brakish to marine and subjected to several phases of transgressions and regressions of the sea. The limestone members were deposited under shallow marine with low-water energy condition. The foraminiferal fossil assemblages indicates as the characteristic found assemblage upper photic zone (depths less than 40 m) under warm and normal salinity of sea water.
The study area, part of Tindivanam taluk in Villupuram district is located between 79°30' to 79°52' east longitude and 12°18' to 12°24' north latitude. The study area consists of granite, granitic gneiss, and Charnockite of Archaean age which are with few intrusions by dolerite dyke and pegmatite. Ground water sample of 50 locations have been collected in two different seasons (pre and post monsoon). The collected samples have been analysed, and the analytical results brought into a digital output using a computer program HYCH. From the digital output, thematic maps such as Total Dissolved Solids, Total Hardness, Corrosivity Ratio, Groundwater Classification and Salinity and Sodium Hazard have been prepared using the GIS environment. It is inferred that the quality of groundwater improves unevenly in different locations with respect to season indicating the recharge is not uniform. An appreciable amount of quality improvement has been observed along the northern and central portion of the study area. The quality improvement in north of the Veedur dam is poor. Groundwater collected from this location during post monsoon show a little reduction in TDS, TH, CR and USSL classification. It is suggested that by constructing large number of artificial recharge structures to trap monsoon rainwater along the northern and central part of the study area will improve the quality of groundwater remarkably. Designing of recharging wells along the southern region will result in considerable improvement both in the quality and quantity of groundwater.
MHD flow of a viscous conducting fluid past a stretched vertical permeable surface with heat source/sink and chemical reaction has been analysed. Constitutive equations for velocity, temperature and concentration have been formulated and solved with specific boundary conditions. Variation of velocity, temperature and concentration have been shown by graphs. The values of skin-friction, rate of heat transfer and concentration gradient have been entered in the tables for various values of fluid parameters like Grashof number, Prandtl number, Schmidt number, Hartmann number, Eckert number, source/sink parameter, permeability parameter and chemical reaction parameter. It is observed that the flow, heat and mass transfer are influenced by the external transverse magnetic field and porosity of the medium. Actually the imposed magnetic field decelerates the flow. The presence of sink reduces the temperature and the source increases the temperature of the fluid which is practically a case. Concentration decreases with the increase of Schmidt number.
Hall effects on hydromagnetic flow and heat transfer in a porous channel have been investigated. Constitutive equations of continuity, momentum and energy have been developed under the physical situations of the problem. Solving such equations, expressions for velocity, temperature, skin-frictions and rates of heat transfer including magnetic induction components have been obtained. The behaviours of MHD flow and temperature are shown by graphs and those of shear stresses and Nusselt Numbers are exhibited by tables. The heat transfer characteristics of the flow taking viscous and Joulean dissipation into account have also been studied. It is observed that the Hall parameter and the permeability factor influence the flow patterns appreciably
The tungstate compounds Ce2(WO4)3, Dy2(WO4)3, Ho2(WO4)3, Er2(WO4)3 and Yb2(WO4)3 have been synthesized by the solid state reaction technique. The synthesized compounds have been characterised by XRD, DTA, TGA and DTG. XRD patterns show them to be orthorhombic. Dielectric constant (K´) and Dielectric loss (K´´) of these compounds have been measured at 1 KHz in the temperature range 303 to 1103 K. The studied compounds have relatively high value of dielectric constant and low value of dielectric loss around 400K.
This paper reports to the investigations on the study of an unsteady two-dimensional laminar boundary layer flow of an incompressible, viscous, electrically conducting fluid past an infinite porous flat plate. The flow was subjected to a uniform transverse magnetic field. The plate was assumed to move with a constant velocity along the direction of fluid flow. The free stream velocity was subjected to an exponentially decreasing small perturbation law. Injection (or blowing) at the plate has also been assumed to vary exponentially with time. We have derived analytical expressions for velocity field in the boundary layer and skin friction at the plate .Variation of velocity in the boundary layer and skin friction at the plate with different amounts of blowing have been shown in various graphs. The investigation shows that the skin friction at the plate can be reduced either by increasing the blowing or by decreasing the applied magnetic field or both. At a given location in the boundary layer, velocity increases with decrease in the amount of injection or with increase in applied magnetic field.
Occurrences of exposures of Late Maastrichtian-Early Danian rocks are found near Sendurai and Niniyur villages along E-W trending ephemeral streams. These exposures contain multiple levels of three types of uniform sized, spherical moulds/casts of presumably unhatched egg precursors of sauropods. Based on the morphological and size characteristics, these moulds/casts are assigned to megaoolithid oogenus provisionally. Each cluster has 7 or 8 moulds aligned circularly. The matrix surrounding these clusters contains typical nanofossil assemblage representative of Latest Maastrichtian. Sediments overlying these clusters, interpreted to be dinosaur nesting sites contain clayey admixture and silty clay/shale deposits that are reported to be weathered products of Deccan volcanic ash. These deposits are followed by bivalve-rich limestones, bioclastic nautilus limestones and calcareous sandstones that are typical of Danian deposits of Anandavadi member of the Niniyur Formation. Preliminary field observations suggest that faunal extinction preceded the Cretaceous-Tertiary boundary (KTB) mass extinction. Further studies are needed to ascertain the paleoenvironmental conditions that contributed to the demise of the dinosaurs. There is an urgent need to preserve this important dinosaur nesting site for geotourism and future studies to understand the geological past.