Sarita Kumari

Image Quality Prediction by Minimum Entropy Calculation for Various Filter Banks

implement image compression using various wavelet filter banks and measure performance with rate distortion characterizations. Various separable filter banks are chosen and compared. Coefficients in the subbands obtained by wavelet decomposition are quantized. The image is then reconstructed from the quantized coefficients, and distortion is measured. Three distortion measures are used: Entropy of reconstructed image, energy retained (ER) and redundancy.

Analysis of Orthogonal and Biorthogonal Wavelet Filters for Image Compression

e present work we analyze the performance of orthogonal and Biorthogonal wavelet filters for image compression on variety of test images. The test images are of different size and resolution. The compression performance is measured, objectively peak signal to noise ratio and subjectively visual quality of image and it is found that Biorthogonal wavelets outperform the orthogonal ones in both the criteria. General Terms Image compression algorithms

Buffer layer selection for CuIn1 − x Ga x Se2 based thin film solar cells

In this work, device modeling and simulation studies have been carried out with a variety of buffer layers over CIGS absorption layer. The band diagram, electric field variation and I/V curves are analyzed and device performance parameters i.e. efficiency, open circuit voltage, short circuit current, quantum efficiency are calculated. The efficiency of CIGS solar cell with ZnSe buffer layer is found comparable with that of CdS layer. The highest short circuit current is found for solar cell with ZnSe buffer layer, whereas the ZnS/CIGS heterojunction provides the highest quantum efficiency in the structures considered. The device physics is discussed and the effect of thickness of buffer layers and absorption layer is studied in order to find a more efficient and stable solar cell.

Ab initio studies of structural, electronic, optical, elastic and thermal properties of CuGaTe2

We have performed ab initio calculations for the structural, electronic, optical, elastic and thermal properties of CuGaTe2. In this study, we used an accurate full potential linearized augmented plane wave (FP-LAPW) method to find the equilibrium structural parameters and to compute the full elastic tensors. We report electronic and optical properties with the recently developed density functional of Tran and Blaha. Furthermore, optical features such as dielectric functions, refractive indices, extinction coefficient, optical reflectivity, absorption coefficients, optical conductivities, were calculated for photon energies up to 30 eV. The thermodynamical properties such as Debye temperature, entropy and Gruneisen parameter, bulk modulus and hardness were calculated employing the quasi-harmonic Debye model at different temperatures (0–1000 K) and pressures (0–8 GPa) and the silent results were interpreted. Most of the investigated parameters are reported for the first time.

Design of Compact Flower Shape Dual Notched-Band Monopole Antenna for Extended UWB Wireless Applications

Abstract In this letter, a compact monopole antenna for ultra wideband (UWB) applications is proposed with small size of 18×20=360 mm2. Antenna consist of a flower shape radiating patch with a pair of C-shaped slots which offer two notch bands for WiMAX (3.04–3.68 GHz) & WLAN (4.73–5.76 GHz) and two rectangular shaped slots in the ground plane which provides a wide measured usable fractional extended bandwidth of 163 % (2.83–14.0 GHz) with improved VSWR. Moreover, it is also convenient for other wireless application as close range radar, 8–12 GHz in X-band. Measured radiation patterns exhibits nearly omnidirectional in H-plane and dipole like pattern in E-plane across the bandwidth and furthermore exhibits good time domain performance.

Modeling and analysis of CuGaS2 thin-film solar cell

The authors have performed, the modeling of thin film CuGaS2 based solar cell with ZnTe buffer layer. The efficiency of the cell, short circuit current density and fill factor are calculated. In addition the effect of thickness of absorption layer over performance parameters of the cell is studied and it is found that maximum efficiency of the cell is achieved for 2000 nm thick absorption layer.