http://nopr.niscair.res.in/handle/123456789/8210 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/8220 Title: Current-mode sinusoidal quadrature oscillator with independent control of oscillation frequency and condition using CDTAs <br/> <br/>Authors: Tangsrirat, Worapong; Tanjaroen, Wason <br/> <br/>Abstract: A current–tunable current-mode sinusoidal quadrature oscillator, constructed from only three current differencing transconductance amplifiers (CDTAs) and two grounded capacitors with the absence of the passive resistors, is presented and analyzed. The proposed oscillator provides the important advantage of non-interactive electronic control of the oscillation condition and the oscillation frequency (ω_o) and is capable of generating two quadrature current outputs. The circuit exhibits low active and passive sensitivities and is suitable for integration. Theoretical results are verified with PSPICE simulations. <br/> <br/>Page(s): 363-366 http://nopr.niscair.res.in/handle/123456789/8219 Title: Dielectric properties of silver sodium niobate mixed ceramic system <br/> <br/>Authors: Nautiyal, Om Prakash; Bhatt, S C; Pant, R P; Semwal, B S <br/> <br/>Abstract: Ceramic pellets of silver sodium niobate (Ag₁_-xNa_xNbO₃) mixed system of different concentration have been prepared by solid-state reaction method and sintering process. The prepared samples were characterized by X-ray diffraction method and SEM techniques. Frequency variations of dielectric constant, loss tangent and electrical conductivity have been investigated at room temperature in the frequency range 10 Hz-10 MHz. <br/> <br/>Page(s): 357-362 http://nopr.niscair.res.in/handle/123456789/8218 Title: Dielectric and micromechanical<b style=""> </b>studies of barium titanate substituted (1-y)Pb (Zn_1/3Nb_2/3)O₃-yPT ferroelectric ceramics <br/> <br/>Authors: Himanshu, A K; Bandyopadhyay, S K; Sen, Pintu; Gupta, D C; Chakraborty, Riya; Mukhopadhyay, Anoop K; Choudary, B K; Sinha, T P <br/> <br/>Abstract: Dielectric studies have been carried out on barium titanate substituted lead zinc niobate ferroelectrics ceramics, (Pb_0.88Ba_0.12)[(Zn­_1/3Nb_2/3)_0.88Ti_0.12)]O₃ and (Pb_0.8Ba_0.2)[(Zn­_1/3Nb_2/3)_0.8Ti_0.2)]O₃. The dielectric dispersion of the solid solutions has been studied as a function of temperature in the frequency range 100 Hz-1MHz. The temperature variation of the real components of dielectric permittivity (<img src='/image/spc_char/italics_e.gif' border=0>^') at different frequencies shows a diffuse phase transition. Micromechanical studies have been carried on (Pb_0.88Ba_0.12)[(Zn­_1/3Nb_2/3)_0.88Ti_0.12)]O₃ and (Pb_0.8Ba_0.2)[(Zn­_1/3Nb_2/3)_0.8Ti_0.2)]O₃by nanoindentation at different loads. Hardness, Young’s modulus, elastic energy and total energy have been extracted. It is seen that in case of (Pb_0.8Ba_0.2)[(Zn­_1/3Nb_2/3)_0.8Ti_0.2)]O₃, the plastic deformation energy is lower than the other sample, which is due to extra Ti content in B-site. This is also reflected in polarization studies, which confirms that the presence of Ti⁴⁺ in B-site brings forth rigidity in Ti-O bond. <br/> <br/>Page(s): 349-356 http://nopr.niscair.res.in/handle/123456789/8217 Title: Field dependent sound attenuation in PbTiO₃ and KNbO₃ ferroelectric perovskites <br/> <br/>Authors: Singh, Talvinder; Kumar, Ashok; Naithani, U C <br/> <br/>Abstract: The electric field dependence of the sound attenuation in anharmonic pure PbTiO₃ and KNbO₃ferroelectric perovskites has been theoretically calculated in paraelectric phase from the Silverman-Joseph Hamiltonian augmented with fourth-order phonon coordinates using double-time Green’s function technique. The attenuation constant increases with increasing temperature and frequency in the presence of an electric field. In the vicinity of phase transition temperature, the anomalously increasing sound attenuation is the consequence of soft mode. The attenuation of sound wave is primarily due to strong interaction with thermally excited phonons in the soft mode. The results obtained are compared with the results of others. <br/> <br/>Page(s): 343-348