A secured image steganography method based on ballot transform and genetic algorithm

Multimedia Tools and Applications - Rapid advances in digital technology have facilitated us to transfer a huge amount of electronic files over the internet. But in the presence of malicious...     

Radial distribution system power flow using interval arithmetic

This paper reports on the application of interval arithmetic technique for balanced radial distribution system power flow analysis. Interval arithmetic takes care of the uncertainty in the input parameters and provides strict bounds for the solution of the problem. In this paper, uncertainties only in the input load parameters are considered. The results are compared with the results obtained from repeated load-flow simulations.     

The use of interlayers in modeling interface crack propagation

Delaminations are a common mode of failure at interfaces between two material layers which have dissimilar elastic constants. There is a well-known oscillatory nature to the singularity in the stress fields at the crack tips in these bimaterial delaminations, which creates a lack of convergence in the modewise energy release rates. This makes constructing fracture criteria somewhat difficult. An approach used to overcome this is to artificially insert a thin, homogeneous, isotropic layer (the interlayer) at the interface. The crack is positioned in the middle of this homogeneous interlayer, thus modifying the original ‘bare’ interface crack problem into a companion ‘interlayer’ crack problem. Individual modes I and II energy release rates are convergent and calculable for the companion problem and can be used in the construction of a fracture criterion or locus. However, the choices of interlayer elastic and geometric properties are not obvious. Moreover, a sound, consistent, and comprehensive methodology does not exist for utilizing interlayers in the construction and application of mixed-mode fracture criteria in interface fracture mechanics. These issues are addressed here. The role of interlayer elastic modulus and thickness is examined in the context of a standard interface fracture test specimen. With the help of a previously published analytical relation that relates the bare interface crack stress intensity factor to the corresponding interlayer crack stress intensity factor, a suitable thickness and elastic modulus are identified for the interlayer in a bimaterial four-point bend test specimen geometry. Interlayer properties are chosen to make the interlayer fracture problem equivalent to the bare interface fracture problem. A suitable mixed-mode phase angle and a form for the fracture criterion for interlayer-based interface fracture are defined. A scheme is outlined for the use of interlayers for predicting interface fracture in bimaterial systems such as laminated composites. Finally, a simple procedure is presented for converting existing bare interface crack fracture loci/criteria into corresponding interlayer crack fracture loci.     

Band gap engineering in huge-gap semiconductor SrZrO3 for visible-light photocatalysis

Using SrZrO₃ (SZO, the intrinsic band gap being 5.6 eV) as an example, we have investigated the design principles for huge-gap semiconductors with band gap larger than 5 eV for the application of efficient visible-light driven photocatalysts for splitting water into hydrogen. Based on the hybrid density function calculations, the electronic structures of mono-doped and co-doped SZO are investigated to obtain design principles for improving their photocatalytic activity in hydrogen generation. The cationic–anionic co-doping in SZO could reduce the band gap significantly and its electronic band position is excellent for the visible-light photocatalysis. This work reports a new type of candidate material for visible-light driven photocatalysis, i.e., huge-gap semiconductors with band gap larger than 5 eV. Furthermore, based on the present results we have proposed the design principles for band gap engineering that provides general guideline for other huge-gap semiconductors.     

Image steganography using deep learning based edge detection

This paper introduces a deep learning-based Steganography method for hiding secret information within the cover image. For this, we use a convolutional neural network (CNN) with Deep Supervision based edge detector, which can retain more edge pixels over conventional edge detection algorithms. Initially, the cover image is pre-processed by masking the last 5-bits of each pixel. The said edge detector model is then applied to obtain a gray-scale edge map. To get the prominent edge information, the gray-scale edge map is converted into a binary version using both global and adaptive binarization schemes. The purpose of using different binarization techniques is to prove the less sensitive nature of the edge detection method to the thresholding approaches. Our rule for embedding secret bits within the cover image is as follows: more bits into the edge pixels while fewer bits into the non-edge pixels. Experimental outcomes on various standard images confirm that compared to state-of-the-art methods, the proposed method achieves a higher payload.

     

Energetic and structural analysis of N2H4BH3 inorganic solid and its modified material for hydrogen storage

Here we have exposed the electronic structure, chemical bonding of the light-weight N₂H₄BH₃ inorganic material for hydrogen storage applications and analyzed its hydrogen removal energetics using state-of-the-art first-principles method. The mechanism for the H-host bond weakening in this kind of solid has also been explored. It is shown that the electronic density of states of N₂H₄BH₃ solid near the Fermi level is mainly contributed by the B p-states, H (B) s-states, and the end N p-states. The calculated smallest hydrogen removal energy of N₂H₄BH₃ solid is 4.16 eV. One Li-modified structure has been obtained through ab initio relaxations and its hydrogen removal energies are found dramatically decreased by as much as 50% compared with those of pristine N₂H₄BH₃ solid. The B–H bond weakening is attributed to the elongation of the bond length; for the N–H bonds, the weakening is found to be due to the destabilization of N–H bonds before hydrogen removal and the stabilization of residual N–H bond after hydrogen removal. The weakening of these bonds is of great significance for the improvement of hydrogen desorption kinetics of the material. We propose this study should help to deepen understanding of properties of N₂H₄BH₃ inorganic solid and its related materials for hydrogen storage applications and guide experimentalists and engineers to develop better candidate materials for the advance of the field.     

Thermophilic dark fermentation of untreated rice straw using mixed cultures for hydrogen production

Biohydrogen production from untreated rice straw using different heat-treated sludge, initial cultivation pH, substrate concentration and particle size was evaluated at 55 °C. The peak hydrogen production yield of 24.8 mL/g TS was obtained with rice straw concentration 90 g TS/L, particle size <0.297 mm and heat-treated sludge S1 at pH 6.5 and 55 °C in batch test. Hydrogen production using sludge S1 resulted from acetate-type fermentation and was pH dependent. The maximum hydrogen production (P), production rate (R_m) and lag (λ) were 733 mL, 18 mL/h and 45 h respectively. Repeated-batch operation showed decreasing trend in hydrogen production probably due to overloading of substrate and its non-utilization. PCR-DGGE showed both hydrolytic and fermentative bacteria (Clostridium pasteurianum, Clostridium stercorarium and Thermoanaerobacterium saccharolyticum) in the repeated-batch reactor, which perhaps in association led to the microbial hydrolysis and fermentation of raw rice straw avoiding the pretreatment step.     

Polyphenol oxidase-based luminescent enzyme hydrogel: an efficient redox active immobilized scaffold

A novel, functionally potent polyphenol oxidase (10000 U)-mediated urchin-shaped composite-based luminescent enzyme hydrogel network as immobilized scaffold for oxido-reductase efficiency on phenolic substrates including phenol, resorcinol, catechol and quinol was synthesized and characterized through fluorescence spectroscopy along with scanning electron microscopy and transmission electron microscopy.