http://nopr.niscair.res.in/handle/123456789/965 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/1044 Title: Realization of CDTA based current-mode universal filter <br/> <br/>Authors: Shah, N A; Quadri, Munazah; Iqbal, S Z <br/> <br/>Abstract: A new current-mode (CM) filter capable of providing simultaneously lowpass (LP), bandpass (BP) and highpass (HP) responses has been presented. The realization of notch and allpass (AP) responses can be easily achieved without matching or rotation of components. The circuit employs a single current differencing transconductance amplifier (CDTA), two capacitors and one resistor. The circuit uses a minimum number of active and passive components and permits orthogonal tunability of pole frequency (ω₀) and bandwidth (ω₀/Q) alongwith enjoying low active and passive sensitivities. PSPICE simulation results are obtained. <br/> <br/>Page(s): 283-285 Sat, 29 Mar 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/1043 Title: Field dependent dielectric behaviour of BaxSr₁₋XTiO₃ perovskites <br/> <br/>Authors: Kukreti, Ashish; Kumar, Ashok; Naithani, U C <br/> <br/>Abstract: Using the method of double time thermal Green’s functions and Kubo formalism, a general expression has been derived for the electric field dependence of the complex dielectric constant of BaxSr₁₋xTiO₃ ferroelectric crystal in the paraelectric phase from the Silverman–Joseph Hamiltonian augmented with fourth order phonon co-ordinates. The change of mass as well as harmonic force constant between impurity atom and host lattice atoms are taken into account. The frequency, temperature and electric field dependent dielectric constant of BaxSr₁₋xTiO₃ crystal has been discussed. Dielectric constant increases with increase of applied field. The results are compared with previous experimental and theoretical results. <br/> <br/>Page(s): 276-282 Sat, 29 Mar 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/1042 Title: Preparation, characterization and sintering behaviour of Sr doped PbZrO₃ powders by self-propagating combustion method <br/> <br/>Authors: Boopathy, K; Nesaraj, A Samson; Rajendran, V <br/> <br/>Abstract: The Sr doped PbZrO₃ (Pb1-xSrxZrO3 ; x=0, 0.05, 0.10, 0.15 and 0.20) ceramics have been prepared by glycine-nitrate self-propagating combustion technique. The ceramic powders have been heat treated at 800°C for 6 h in order to get phase pure compounds. The prepared powders are characterized by XRD, density and BET surface area measurements. The XRD patterns obtained on these powders show the formation of pure orthorhombic phase of PbZrO₃ without any impurities. Thin sections of circular components of these powders, made by uniaxial compression, are subjected to annealing at different temperatures in the range 900-1100°C for 2 h in order to throw light on their sintering behaviour. The surface morphology of the sintered components are studied by SEM. <br/> <br/>Page(s): 270-275 Sat, 29 Mar 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/1041 Title: Photoelectret study of Sm doped ZnO and ZnO-Pb₃O₄mixed lattice <br/> <br/>Authors: Srivastava, Rajneesh Kumar; Prakash, S G <br/> <br/>Abstract: The photoelectret characteristics of rare earth ion Sm doped ZnO and ZnO-Pb₃O₄ along with pure ZnO have been studied. The dependence of photoelectret charge on excitation field, photo polarization time, dark depolarization time, intensity and wavelength of illumination have been evaluated. With increase in polarization time, decrease in depolarization time and increase in intensity of illumination, photoelectret charge continues to increase. With increase in field, photoelectret charge first increases and later tends to saturation. No photoelectret effect was observed in nano structured ZnO. <br/> <br/>Page(s): 266-269 Sat, 29 Mar 2008 22:58:59 GMT