The Energetics of Li Off-Centering in K1−x_{1-x}Lix_xTaO3_3; First Principles Calculations

K$_{1-x}$Li$_{x}$TaO$_3$ (KLT) solid solutions exhibit a variety of interesting physical phenomena related to large displacements of Li-ions from ideal perovskite A-site positions. First-principles calculations for KLT supercells were used to investigate these phenomena. Lattice dynamics calculations for KLT exhibit a Li off-centering instability. The energetics of Li-displacements for isolated Li-ions and for Li-Li pairs up to 4th neighbors were calculated. Interactions between nearest neighbor Li-ions, in a Li-Li pair, strongly favor ferroelectric alignment along the pair axis. Such Li-Li pairs can be considered "seeds" for polar nanoclusters in KLT. Electrostriction, local oxygen relaxation, coupling to the KT soft-mode, and interactions with neighboring Li-ions all enhance the polarization from Li off-centering. Calculated hopping barriers for isolated Li-ions and for nearest neighbor Li-Li pairs are in good agreement with Arrhenius fits to experimental dielectric data.Comment: 14 pages including 10 figures. To Physical Review B. Replaced after corrections due to referees' remark

Coherent steganography using Segmentation and DCT

The important issue of modern communication is establishing secret communication while using public channel and is achieved by steganography. In this paper, we propose Coherent Steganographic Technique using Segmentation and Discrete Cosine Transform (CSSDCT). The cover image is divided into 8*8 blocks and DCT is applied on each block. The number of payload MSB bits is embedded into DCT coefficients of the cover image coherently based on the values of DCT coefficients. It is observed that the proposed algorithm has better PSNR, Security and capacity compared to the existing techniques. © 2010 IEEE

Integration of Spatial and Transform Domain in LSB Steganography

In this paper, we propose an integration of spatial and transform domains in LSB steganography (ISTDLS) where both the cover image as well as payload are divided into two cells each and RGB components of cell-1 are separated. The extracted RGB components of cover image cell-1 are individually transformed from spatial to transform domain using FFT/DCT/DWT and embedded differently, the components of cell-2 are retained in spatial domain itself

Dual transform technique for robust steganographya

Steganography enables to have a secret communication in modern information technology using public channel. In this paper, we propose Dual Transform Technique for Robust Steganography (DTTRS). The cover image is segmented into blocks of 4*4 each and Discrete Wavelet Transform (DWT) is applied on each block. In the resulting DWT coefficients, blocks of vertical band of 2*2 each are considered and Integer Wavelet Transform (IWT) is applied to get blocks of 1*1 each. The IWT is applied on vertical band of DWT of payload to generate coefficients of payload and are embedded into IWT coefficients of cover image using least significant bit replacement method. On applying IIWT and IDWT, stego image is derived. The concept of error detecting and correcting coding technique is employed to ensure more reliable communication. It is observed that the proposed algorithm has excellent PSNR, provides high level security and more robust compared to individual transform techniques. © 2011 IEEE

Hybrid fingerprint matching using block filter and strength factors

Fingerprint verification is a socially accepted biometric method for identification of a person. In this paper we propose Hybrid Fingerprint Matching using Block Filter and Strength Factor (HFMBFS). The minutiae and ridge based methods are combined to verify the fingerprint matching using strength factors Alpha (α) and Beta (β). For minutiae and ridge extraction Block Filter and Hough Transform are used respectively. It is observed that the matching percentage of two different fingerprints is improved compared to the existing algorithms. © 2010 IEEE

Iris recognition based on DWT and PCA

An Iris is unique compared to all other biometric and is used to authenticate a person. In this paper, we propose iris recognition based on DWT and PCA (IRDP). The iris region is localized using morphological process and a template is formed by using the left and right part of the iris to the pupil by discarding the upper and lower parts of the iris as they are usually occluded by eyelids and eyelashes. The DWT is applied on the histogram of iris template. The features are generated from the approximation band of the DWT using PCA. The classifiers viz., KNN, RF and SVM are used for matching. It is observed that the proposed algorithm has better performance parameters compared to existing algorithm. © 2011 IEEE