V. S. Pandey

Bio: V. S. Pandey is an academic researcher from National Institute of Technology Delhi. The author has contributed to research in topics: Dielectric resonator antenna & Antenna (radio). The author has an hindex of 18, co-authored 48 publications receiving 953 citations. Previous affiliations of V. S. Pandey include Kyung Hee University & Allahabad University.

Flow and thermal analysis on Darcy-Forchheimer flow of copper-water nanofluid due to a rotating disk: A static and dynamic approach

Abstract: Background Characterised with augmented heat transport and thermal efficiency, nanofluids are implementable in diversified applications include pharmaceutical industries, hybrid-powered machines, cooling of different appliances, refrigerator, microelectronic, heat exchanger etc. Taking such advantages into mind, physical aspects of entropy optimization and non-linear thermal radiation in Darchy–Forchheimer flow of copper–water nanofluid due to a rotating disk are examined. A new thermal conductivity model of nanofluids involving static and dynamic approach is considered. This model signifies hydrodynamic interaction among the Brownian motion induced fluid particles. The Cattaneo–Christov heat flux theory is taken into account. The second law of thermodynamics is the instrumental for the determination of total entropy generation rate. Methods The system of nonlinear PDEs is converted into system of nonlinear ODEs through favorable transformations. Shooting technique has been applied prospectively to accomplish the desired numerical solution of the transformed equations. Results The behavior of velocity (axial, transverse and tangential) and thermal fields influenced by varied physical parameters is impressed through graphs and numerical tables. Velocity field peters out due to rising porosity parameter as well as volume fraction while thermal field upgrades for higher Biot number and radiation parameter. Significant heat transfer rate is obtained for smaller estimation of radiation parameter. Entropy generation rate and Bejan number exhibit similar trend for radiation parameter and opposite fashion for Reynolds number. Conclusions The diminishing velocity distribution for larger access of porous matrix while elevated temperature distribution for higher temperature parameter (due to nonlinear thermal radiation). Entropy minimization is accomplished for grater estimation of Brinkman and Reynolds numbers.

Wide Band Circularly Polarized Dielectric Resonator Antenna With Stair-Shaped Slot Excitation

Abstract: A singly-fed wideband circularly polarized dielectric resonator antenna is proposed in this communication. Antenna structure contains a rectangular and two half split cylindrical dielectric resonators. Multiple orthogonal modes are excited in the antenna structure when excitation is applied through a stair-shaped slot. Measured results show that antenna provides wider 3-dB axial ratio and impedance bandwidths of 41.01% and 49.67%, respectively. Proposed antenna can be utilized in C-band applications.

Design Of Analog Cmos Integrated Circuits

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Alfven Waves in the Solar Corona

Abstract: Alfven waves, transverse incompressible magnetic oscillations, have been proposed as a possible mechanism to heat the Sun's corona to millions of degrees by transporting convective energy from the photosphere into the diffuse corona. We report the detection of Alfven waves in intensity, line-of-sight velocity, and linear polarization images of the solar corona taken using the FeXIII 1074.7-nanometer coronal emission line with the Coronal Multi-Channel Polarimeter (CoMP) instrument at the National Solar Observatory, New Mexico. Ubiquitous upward propagating waves were seen, with phase speeds of 1 to 4 megameters per second and trajectories consistent with the direction of the magnetic field inferred from the linear polarization measurements. An estimate of the energy carried by the waves that we spatially resolved indicates that they are too weak to heat the solar corona; however, unresolved Alfven waves may carry sufficient energy.

An optimization approach to reconstructing force-free fields from boundary data: I. Theoretical basis.

Abstract: A new method for reconstructing force-free magnetic fields from their boundary values, based on minimizing the global departure of an initial field from a force-free and solenoidal state, is presented. The method is tested by application to a known nonlinear solution. We discuss the obstacles to be overcome in the application of this method to the solar case: the reconstruction of force-free fields in the corona from measurements of the vector magnetic field in the low atmosphere.

A contemporary view of coronal heating

Abstract: Determining the heating mechanism (or mechanisms) that causes the outer atmosphere of the Sun, and many other stars, to reach temperatures orders of magnitude higher than their surface temperatures...