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Pratihar A.K.,nt University Of Ag And Technology | Kaushik S.C.,Indian Institute of Technology Delhi | Agarwal R.S.,Indian Institute of Technology Delhi
Applied Thermal Engineering | Year: 2012

Simulation of a 100 kW ammonia-water compression-absorption system has been carried out for water chilling application by incorporating detailed heat and mass transfer calculations in the absorber and desorber of the system. Warner's technique has been used for the convergence of iterations. The effect of relative solution heat exchanger area on the COP, cooling capacity, absorber heat load and effectiveness of solution heat exchanger has been studied. With increase in the relative solution heat exchanger area from 17 to 50%, COP increases initially, becomes maximum at 39% and then decreases. However, capacity of the system decreases considerably as a result of increase in relative solution heat exchanger area. Due to pressure drop in the solution heat exchanger on weak solution side, pumping power increased by 30% but COP decreased by only 0.92%. The performance of this system has been compared with that of a conventional vapor compression type chiller. © 2011 Elsevier Ltd. All rights reserved. Source

Paras,nt University Of Ag And Technology | Gangwar R.P.S.,nt University Of Ag And Technology
International Journal of Microwave and Optical Technology | Year: 2011

A compact size, multiband 2x2 array of circular microstrip antenna has been proposed. The antenna array consists of Genetic Algorithm (GA)-optimized, annular slotted circular microstrip antenna elements using probe feed. The spacing of elements has also been optimized using GA in the two directions. The performance of the antenna array has been studied with different shape parameters. The optimized antenna array exhibits the tri-band characteristics in wireless bands that can be used in WLAN, Wi-MAX, airborne, satellite and radar applications. Its output parameter results have been compared with the previously implemented design results in the corresponding operation bands. It has been shown that by switching the wave excitations in the selected elements, the desired radiation characteristics can be obtained. Also very good circular polarization characteristics have been obtained for the optimized array. © 2011 ISRAMT. Source

Saluja B.,nt University Of Ag And Technology | Gupta A.,nt University Of Ag And Technology | Goel R.,nt University Of Ag And Technology
Ekologija | Year: 2011

Arsenic is a naturally occurring element and its contamination of soil and groundwater is a major threat to the environment and human health. The ubiquity of arsenic in the environment has led to the evolution of the arsenic defence mechanism in certain microbes. The present study highlights identical mechanisms of arsenic resistance in two bacterial strains, namely AG24 and AGM13, which were taken from two different ecosources and states of India. The phylogenetic analysis of the strains using 16S rDNA sequence revealed both strains to be under the genus 'Bacillus'. Furthermore, arsC gene was amplified from the strains, cloned and sequenced. The homology of the sequences of the two strains, when compared with available database using BLASTn search, showed that the 300bp amplicons obtained in both strains possess a partial arsC gene sequence which codes for arsenate reductase, an enzyme involved in the reduction of arsenate to arsenite, which is then effluxed out of the cell. Nevertheless, atomic absorption spectroscopy and scanning electron microscopy analysis of both strains also strengthen the presence of the efflux mechanism. Thus, the presence of a similar mechanism of resistance in both strains suggests the possible role of lateral gene transfer from soil to water system and vice versa which is an alarming situation for global concern. © Lietuvos mokslu akademija, 2011. Source

Dixit G.,nt University Of Ag And Technology | Singh J.P.,nt University Of Ag And Technology | Srivastava R.C.,nt University Of Ag And Technology | Agrawal H.M.,nt University Of Ag And Technology | And 2 more authors.
Surface and Interface Analysis | Year: 2010

Nickel ferrite is a softmagneticmaterialwith inverse spinel structure. Soft ferrite films are used inmicrowave devices, integrated planar circuits, etc., because of their high resistivity. In this work, thin films of nickel ferrite were deposited on Si (100) substrate by using pulsed laser deposition (PLD) technique. The thickness of the film was measured by surface profilometer and also by X-ray reflectivity (XRR). The films were annealed at three different temperatures to observe the effect on the structural and magnetic properties of the film. The films were characterised by X-ray diffraction (XRD), Raman spectroscopy and vibrating samplemagnetometer (VSM) to study the structural andmagnetic properties. Copyright © 2010 John Wiley & Sons, Ltd. Source

Negi P.,nt University Of Ag And Technology | Kumar H.,nt University Of Ag And Technology | Agrawal H.M.,nt University Of Ag And Technology | Srivastava R.C.,nt University Of Ag And Technology
AIP Conference Proceedings | Year: 2013

The specific heat and dielectric properties of multiferroic GdMnO 3 synthesized by modified sol-gel technique has been investigated. GdMnO3 crystallized in orthorhombic perovskite structure. X-ray diffraction was used to investigate the structural information. Morphology has been investigated by field emission scanning electron microscope and the average grain size is found to be ∼ 552 nm. Magnetic anomalies have been observed in specific heat and dielectric properties of GdMnO3. © 2013 American Institute of Physics. Source

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