http://nopr.niscair.res.in/handle/123456789/9955 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/9967 Title: Realization of variable <i>Q</i> bandpass filter using low-voltage CCII <br/> <br/>Authors: Sharma, Susheel; Rana, Seema; Pal, K <br/> <br/>Abstract: A voltage-mode bandpass filter with variable <i>Q</i>, realized using a single FGMOS based second generation current conveyor (CCII) that operates with ± 0.75 V supply voltage, has been presented. The <i>Q </i>and pass band gain (<i>K</i>) can be adjusted for desired values within some limits by selecting the various passive components used in the circuit. The workability of this circuit has been<b> </b>verified by PSpice simulations using 0.5 mm technology parameters. <br/> <br/>Page(s): 600-602 Thu, 29 Jul 2010 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/9966 Title: Multiferroic Pb₁_-xSr_x(Fe_0.012Ti_0.988)O₃ nanoparticles: Room temperature dielectric relaxation, ferroelectricity and ferromagnetism <br/> <br/>Authors: Verma, Kuldeep Chand; Ram, Mast; Kotnala, R K; Bhatt, S S; Negi, N S <br/> <br/>Abstract: The effect of particles size and lattice parameters on dielectric constant, ferroelectricity, ferromagnetism and <i style="">dc</i> resistivity of Pb₁_-xSr_x(Fe_0.012Ti_0.988)O₃ (PSFT) nanoparticles has been studied at room temperature. The PSFT nanoparticles were prepared by a chemical synthesis route. The X-ray diffraction patterns confirm the phase structure of PSFT nanoparticles. The tetragonal distortion (<i style="">c/a</i>) and particles size have been reduced with increasing Sr²⁺ ion substitution. The microstructural behaviour shows the average particle’s size of PSFT specimens which lie in the range of 4-13 nm. The Sr-doped PSFT specimens show higher value of dielectric constant than undoped PFT. At 30 mol% of Sr concentration, the PSFT specimen shows dielectric relaxation up to 18 MHz with ε = 101 and tan '/image/spc_char/delta1.gif' border=0&gt; = 0.075. Also, the maximum value of saturation magnetization, <i style="">M</i>_s = 64.4×10^-3emu/g with low magnetic coercive field, <i style="">H</i>_c = 35.9 Oe, and spontaneous polarization, <i style="">P_s</i> = 20.7 μC/cm², remanent polarization, <i style="">P</i>_r = 13.3 μC/cm² and electric coercive field, <i style="">E</i>_c<i style=""> </i>= 5.7 kV/cm have been observed. Compositional plots between average particle’s size and <i style="">dc</i> resistivity, and dielectric constant and saturation magnetization have been given. <br/> <br/>Page(s): 593-599 Thu, 29 Jul 2010 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/9965 Title: Constructal minimization of emitter grid resistance of solar cell with variable cross-section collectors <br/> <br/>Authors: Chen, Lingen; Zhou, Shengbing; Sun, Fengrui <br/> <br/>Abstract: In constructal theory, the optimal shape (geometry) and structure of nature and engineered systems are the outcome of their functionality and resources and constraints. The constructal volume-point flow model is applied to the design and performance optimization of solar cells in this paper. The optimal electrode distribution in emitter of a solar cell is obtained by using optimized variable cross-section collectors and rectangular elemental areas. The minimum series electrical resistance is taken as optimization objective. The minimum series electrical resistance obtained herein is smaller than that obtained by using optimized constant cross-section collectors. The results show that the constructal design succeeds to compromise effectively the conflict between decreasing the series electrical resistance and decreasing shadow for the design of solar cells. <br/> <br/>Page(s): 586-592 Thu, 29 Jul 2010 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/9964 Title: Effect of preparative conditions on magnetic properties of CoFe₂O₄ nanoparticles <br/> <br/>Authors: Parekh, Kinnari <br/> <br/>Abstract: Nanomagnetic particles of CoFe₂O₄ have been synthesized using chemical co-precipitation technique followed by annealing, characterized and investigated by powder XRD and magnetic measurement tools. All samples of nano ferrites synthesized at different annealing temperatures show single phase cubic spinel structure with particle size changes from 9.5 to 21 nm. The virgin curve of magnetic measurement exhibits superparamagnetic behaviour at room temperature which changes to ‘S’ shape with increasing annealing temperature indicating change in soft magnet to pinning-type magnet. The coercivity of the nano-cobalt ferrite particles has been found to increase with increase in annealing temperature. <br/> <br/>Page(s): 581-585 Thu, 29 Jul 2010 22:58:59 GMT