The National Institute of Technology, Srinagar is a national engineering institute located in Hazratbal, Srinagar, Jammu and Kashmir, India and an engineering institute of Northern India, along with other NITs and IITs of India. It is one of the 30 NITs in India, and as such is directly under the control of the Ministry of Human Resource Development . It is the 7th in the chain of 17 NITs established as a part of the Second Five Year Plan by the Government of India. Refer History of RECs for more information on the Regional Engineering College established during the 2nd five year plan . The institute has recognition as an Institute of National Importance under NIT act of Parliament and has produced more than 8000 graduates. Wikipedia.
Harmain G.A.,National Institute of Technology Srinagar
Theoretical and Applied Fracture Mechanics | Year: 2010
Many engineering components are subjected to variable amplitude loading history. It is well known that retardation in fatigue crack growth occurs due to application of single overloads in a constant amplitude loading block. Many models have been proposed to capture this counter intuitive phenomenon which has resulted in improved understanding of retardation effect following tensile overloads and consequently resulting in better life prediction models. The proposed study is focused on to evaluation of retardation in fatigue life due to application of a single overload. A model for prediction of crack growth and crack growth rate following single overloads is presented. Several modifications to Wheeler's growth idea are proposed, which incorporate a consideration for effective stress intensity factor, based on Elber's concept of crack closure, relationship between overload ratio and the Wheeler's exponent, and fatigue growth rate calculations. The results presented here show that plastic zone interaction following overload and the consideration of crack closure explain retardation effect following a single overload. Correlation between analysis and experimental data obtained from several sources in literature show that the scheme, is robust and provides an insight into the nonlinear aspect of crack growth results. The model has been tested for 2024-T3 aluminum alloy and 6061-T6 aluminum alloy and thorough calibrations performed, established the fidelity of the program. © 2009 Elsevier Ltd. All rights reserved.
Khan G.R.,National Institute of Technology Srinagar
Journal of Lightwave Technology | Year: 2013
An exact analytical formulism obtained directly by solving a system of rate and propagation equations in the presence of pump excited-state absorption is presented on the basis of four-band transition scheme in radially symmetric and longitudinally uniform monomode erbium doped silica fiber lasers. The exact analytical expressions are determined for overall gain, small-signal gain, pump intensity threshold, lasing threshold condition, and optimal fiber length in terms of alleviative measurable quantities of photon intensities, transition rates, absorption and emission cross sections, and reflectivity of mirrors. Mutatis mutandis, the formulas bear a verisimilitude to analytical expressions appearing in the literature for these parameters. © 2013 IEEE.
Shah M.A.,National Institute of Technology Srinagar
Materials Science Forum | Year: 2013
Magnesium oxide (MgO) nanoneedles have been prepared by an environmentally benign route. The route is based on a very simple reaction of magnesium powder and double distilled water at very low temperature of 50°C. The formation of nanostructures by the reaction of metals with water is suggested to occur due of decomposition of water by the metal giving hydrogen. The nanoneedles have an average width of 20nm and length up to 1μm. Compared with other methods, the present method is fast, economical, low temperature and free of pollution which will make it suitable for large scale production. © (2013) Trans Tech Publications, Switzerland.
Khan G.R.,National Institute of Technology Srinagar
Optical Fiber Technology | Year: 2012
Analytical solutions to rate and propagation equations describing gain in terms of photon intensities, transition rates, and absorption and emission cross-sections is determined in radially symmetric and longitudinally uniform monomode erbium doped silica fiber in presence of pump excited-state absorption effect for a pumping wavelength of 514.5 nm under the steady-state conditions with the help of a homogenous four-band transition scheme. © 2012 Elsevier Inc. All rights reserved.
Sultan K.,National Institute of Technology Srinagar |
Ikram M.,National Institute of Technology Srinagar |
Asokan K.,Inter University Accelerator Center
Vacuum | Year: 2014
Polycrystalline bulk samples of PrFe1-xMnxO 3 (x = 0.0, 0.1, 0.3, 0.5) were synthesized by solid state reaction method to understand their structural, optical and dielectric properties. X-ray diffraction (XRD) and Raman spectroscopy were investigated to confirm chemical phase and the orthorhombic pbnm structure. As the concentration of Mn increases, the lattice parameter b increases while the lattice parameters a and c/√2 decrease but the change of former is less than later. PrFe1-xMn xO3 exhibits O-type (a < c/√2 < b) orthorhombic pbnm structure upto x = 0.5. From XRD it is also evident that the peaks shift towards higher 2θ values with increase in Mn content indicating the development of strain in the crystal structure possibly due to Jahn-Teller distortion after the incorporation of Mn3+ ions in the parent compound PrFeO3. From the Raman study, the modes exhibit a blue shift with broadening of spectral features in the doped samples. The observed shift in wave number with doping clearly indicates change in the bond lengths of Fe-O/Mn-O as well as their impact on FeO6/MnO6 octahedra. The dielectric constant (É′) and dielectric loss (tan δ) are also studied as a function of frequency and temperature. The dielectric constant and ac conductivity increases with Mn doping. The variation of dielectric properties such as ac conductivity, tan δ and É′ suggests that small polarons contribute to the conduction mechanism. Activation energy (Eσ) and optical band gap (E g) decreases with the concentration of Mn. The observed higher values of these quantities reveals that there is hopping between Mn3+ to Mn4+ and Fe3+ to Fe2+ at the octahedral sites of the compound. Possible mechanism contributing to these processes has been discussed. © 2013 Elsevier Ltd. All rights reserved.