http://nopr.niscair.res.in/handle/123456789/15074 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/15122 Title: Multiple-input-multiple-output log-domain universal biquad filter <br/> <br/>Authors: Shah, N A; Khanday, F A <br/> <br/>Abstract: A simple log-domain technique based Multiple-Input-Multiple-Output (MIMO) universal biquad realizing simultaneously all the standard filtering functions viz; Lowpass (LP), Highpass (HP), Bandpass (BP), Bandstop (BS), and Allpass (AP) is presented in this paper. The biquad being designed by log-domain technique offers all its advantages. The circuit besides permitting independent electronic adjustment of pole frequency (ω_{<span style="mso-bidi-font-style: italic">o</span>}) and the Quality factor (<i>Q</i><span style="mso-bidi-font-style: italic">) is: simultaneously Single-Input-Multiple-Output (SIMO) and Multiple-Input-Single-Output (MISO), free from matching conditions, capable of absorbing the shunt parasitic capacitances, amenable for monolithic integration, composed of merely a few exponential transconductor cells and grounded elements. The other features of circuit are its low sensitivity and good linearity. Simulated and experimental results are obtained to prove the theoretical analyses. </span> <br/> <br/>Page(s): 928-934 http://nopr.niscair.res.in/handle/123456789/15121 Title: Effect of growth interruption on photoluminescence of self-assembled InAs/GaAs quantum dot heterostructures <br/> <br/>Authors: Wu, Ya-Fen <br/> <br/>Abstract: The effects of growth interruption (GI) on self-assembled InAs/GaAs quantum dot (QD) heterostructures have been presented. Samples with different GI times were grown on GaAs substrate by metal-organic chemical vapour epitaxy. Photoreflectance and temperature dependent photoluminescence (PL) spectra from the samples were measured. It is found that increasing GI time during InAs QDs formation induces a larger dot size and a higher QD size uniformity. The carrier dynamics in QD system has been investigated in detail by analyzing the PL spectra. With increasing temperature, thermal redistribution effect among dots is evident for the sample with shorter GI time, leading to a quick red-shift of the PL peak energy and a reduction of the PL line width in mid-temperature range. On the other hand, for sample with longer time, such effect is weak and overcome by the electron-phonon scattering effect, which is consistent with the observed monotonically increasing linewidth of PL spectra with temperature. <br/> <br/>Page(s): 922-927 http://nopr.niscair.res.in/handle/123456789/15120 Title: Free-volume theory of the Grűneisen parameter at extreme compression <br/> <br/>Authors: Shanker, J; Anand, K; Singh, P K <br/> <br/>Abstract: An analysis of the Grűneisen parameter and its volume derivatives has been presented using the generalized free-volume theory for materials at extreme compression. It has been re-established using a direct and simple method that the Slater’s formula for the Grűneisen parameter has the status of an identity at infinite pressure as found earlier by Stacey and Davis (<i style="mso-bidi-font-style:normal">Phys Earth Planet Inter</i>, 142 (2004) 137). The expressions based on the free-volume theory extrapolated to infinite pressure are found to be in agreement with the corresponding expressions for higher-order Grűneisen parameters obtained recently by Shanker <i style="mso-bidi-font-style:normal">et al</i>. (<i style="mso-bidi-font-style: normal">Physica B</i>, 404 (2009) 4083). <br/> <br/>Page(s): 918-921 http://nopr.niscair.res.in/handle/123456789/15119 Title: Polarizability factor for Na₁_{<span style="font-family:Symbol;mso-ascii-font-family:"Times New Roman"; mso-hansi-font-family:"Times New Roman";mso-char-type:symbol;mso-symbol-font-family: Symbol" lang="EN-US">-x</span>}K_xTaO₃ mixed ceramics <br/> <br/>Authors: Uniyal, Manish; Bhatt, S C; Gairola, R P <br/> <br/>Abstract: Considering a quadratic anharmonic model Hamiltonian and using double time temperature dependent Green’s function method and Dyson’s equation treatment, expression for polarizability in the frequency response for mixed perovskite type ferroelectrics has been obtained. Using the experimentally observed temperature dependent dielectic constant, loss tangent, soft mode frequency, width for Na₁_{<span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";="" mso-hansi-font-family:"times="" roman";mso-char-type:symbol;mso-symbol-font-family:="" symbol"="" lang="EN-GB">-x</span>}K_xTaO₃ (<i style="mso-bidi-font-style:normal">x </i>= 0, 0.2, 0.4, 0.5 and 0.6) the polarizability has been calculated for these samples at 10 kHz <br/> <br/>Page(s): 915-917