Design and analysis of text document clustering using salp swarm algorithm

The Journal of Supercomputing - In the technological era, exponential increase of unorganized text documents offers increased difficulties retrieving the most relevant data. The document clustering...     

Secure Key Management Based Mobile Authentication in Cloud

Authentication is important to the security of user data in a mobile cloud environment. Because of the server’s user credentials, it is subject to attacks. To maintain data authentication, a novel authentication mechanism is proposed. It consists of three independent phases: Registration, login, and authentication and key agreement. The user registers with the Registration Center (RC) by producing a secret number that isn’t stored in the phone, which protects against privileged insider attacks. The user and server generate a nonce for dynamic user identity and agree on a session secret key for safe communication. The passwords are not stored on the computer or provided in plain text, they are resistant to replay, guessing, and stolen verification attacks. The suggested protocol uses a one-way hash function and XOR operations, with the client having remote access to a large number of servers over a secure communication channel. Concentrates on HMAC and SHA3 for Collision Free Hashing and to overcome length extension attacks. HMACs are substantially less affected by collisions than their underlying hashing algorithms alone. So adding an HMAC to an MD5 or SHA hash would make it substantially more difficult to break via a rainbow table.     

Investigation of process parameters influence in abrasive water jet cutting of D2 steel

In the present experimental study, abrasive water jet (AWJ) cutting tests were conducted on D2 steel by different jet impingement angles and abrasive mesh sizes. The experimental data was statistically analyzed using the simos–grey relational method and ANOVA test. In addition, the outcome of influencing cutting parameters, namely jet pressure, jet impingement angle, and abrasive mesh size on the different response parameters, namely, the jet penetration, material removal rate, taper ratio, roughness, and topography, were studied. Micro-hardness test and surface morphology analysis were employed to examine the D2 cut surfaces at different AWJ cutting conditions. The chemical element study was performed to determine the abrasive particle contamination in the AWJ kerf wall cut surfaces. The ANOVA test result indicated the jet pressure and jet impingement angle as the influencing process parameters affecting the various performance characteristics of AWJ cutting. The overall AWJ cutting performance of the D2 steel has been improved through proper identification of the optimal process parameter settings, namely jet pressure 225?MPa, abrasive mesh size #100, and jet impingement angle 70° by the simos–grey relational analysis.     

Surface integrity studies on abrasive water jet cutting of AISI D2 steel

This article investigates the 3D surface topography and 2D roughness profiles, and micrographs were analyzed in the abrasive water jet (AWJ) cutting of AISI D2 steel kerf wall cut surfaces by varying water jet pressures and jet impact angles. In 3D surface topography, roughness parameters such as Sq, Ssk, Sp, Sv, Sku, Sz, and Sa were improved by various jet impact angles with different water jet pressures. However, the roughness parameters Ssk and Sku strongly depend on the water jet pressure and jet impact angle. This is confirmed by kerf wall cut profile structures. Fine irregularities of peaks and valleys are found on the AWJ cut surfaces, as evident from 2D roughness profiles. The scanning electron microscope micrographs confirm the production of an upper zone not very much damaged and a lower striation free bottom zone, by using the jet impact angle of 70° with a water jet pressure of 200?MPa. Finally, the results indicate a jet impact angle of 70° maintaining the surface integrity of D2 steel better than normal jet impact angle of 90°. The results are useful in mating applications subjected to wear and friction. This has resulted in enhancement of the functionality of the AWJ machined D2 steel components.     

A comprehensive review on bioinspired solar photovoltaic cells

Researchers have derived inspiration from the biophotosynthetic structures in nature and have started to synthesize the modified bioinspired solar cells copying the evolved organic and inorganic material properties. One of the highlighted examples of bioinspired photo voltaic (PV) cells is the astonishing achievement of an increase in the absorption of integrated sunlight waves in unpatterned solar cells simulated from the wings of the butterfly. Further, deployment possibilities of incorporating flexible cells on flat or curved surfaces for optimizing performance are also under progress. This article mainly discusses the recent concepts of bioinspired solar cells at the research and development level with the prospects and challenges that lie ahead in the upcoming field of photovoltaic renewable energy cell technology. Different potential materials found suitable for bioinspired solar cells construction are reviewed with their particular challenges.     

The role of environmental factors and medium composition on bacteriocin production by an aquaculture probiotic Enterococcus faecium MC13 isolated from fish intestine

The aim of this study was to optimize medium composition for higher yield of total viable cells and bacteriocin by Enterococcus faecium MC13. The factors such as peptone, meat extract, yeast extract, lactose, glycerol, tween 80, triammonium citrate and K₂HPO₄ were selected based on the Lactobacillus MRS medium composition. Two level factorial designs (FD) and steepest ascent path were performed to identify vital factors among the variables. Through the 2^?8 FD, peptone, yeast extract and lactose were found to be significant factors involved in the enhanced production of viable cells and bacteriocin. Therefore, these three foremost factors were further optimized by central composite design to achieve efficient yield. The optimum MRS composition was found to be peptone (40.0 g/L), meat extract (30.0 g/L), yeast extract (40.0 g/L), lactose (24.0 g/L), glycerol (5.8 g/L), Tween 80 (3.0 g/L), triammonium citrate (1.0 g/L), K₂HPO₄ (2.5 g/L), MgSO₄·7H₂O (0.10 g/L), MnSO₄·7H₂O (0.05 g/L) and dipotassium PO₄ (2.0 g/L). The optimized growth medium allowed higher amount of bacteriocin activity (36,100 AUml^?1) and total viable cells (14.22 LogCFUml^?1) production which were two-times higher than the commercial MRS medium.     

Ionic liquid mediated synthesis of silica/polystyrene core–shell composite nanospheres by radical dispersion polymerization

This report describes the novel preparation of silica/polystyrene (SiO₂/PS) core–shell composite nanospheres by in situ radical dispersion polymerization in an ionic liquid (IL). Silica nanoparticles were first surface modified by the silane coupling agent methacryloxypropyltrimethoxysilane (MPTMS), which is capable of copolymerizing with styrene and provided a reactive CC bond. Transmission electron microscopy (TEM) revealed core–shell morphology with smooth surfaces. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that almost all of the SiO₂ nanoparticles were encapsulated by the polymer. The composite particles were also analyzed by FT-IR spectroscopy and thermogravimetric analysis (TGA). In principle, this simple and environmentally-friendly synthetic procedure can be employed to prepare other inorganic oxide-containing polymer composites.     

Secret Image Communication Scheme Based on Visual Cryptography and Tetrolet Tiling Patterns

Visual cryptographic scheme is specially designed for secret image sharing in the form of shadow images. The basic idea of visual cryptography is to construct two or more secret shares from the original image in the form of chaotic image. In this paper, a novel secret image communication scheme based on visual cryptography and Tetrolet tiling patterns is proposed. The proposed image communication scheme will break the secret image into more shadow images based on the Tetrolet tiling patterns. The secret image is divided into 4×4 blocks of tetrominoes and employs the concept of visual cryptography to hide the secret image. The main feature of the proposed scheme is the selection of random blocks to apply the tetrolet tilling patterns from the fundamental tetrolet pattern board. Single procedure is used to perform both tetrolet transform and the scheme of visual cryptography. Finally, the experimental results showcase the proposed scheme is an extraordinary approach to transfer the secret image and reconstruct the secret image with high visual quality in the receiver end.     

Machinability study of abrasive aqua jet parameters on hybrid metal matrix composite

The present work involves investigation of the abrasive aqua jet (AAJ) machining of hybrid metal matrix which consists of Al 6063 reinforced with boron carbide (B₄C) and zirconium silicate (ZrSiO₄) in the form of particulates in the proportion of 5% B₄C and 5% ZrSiO₄. The Response surface method using a central composite design was adopted for conducting experiments by changing the aqua jet pressure, abrasive flow rate, and traverse rate. The results were taken with different types of abrasives of various mesh sizes in this study, which were analyzed using response surface graphs. The striation effect on the bottom-machined surfaces was also examined using the striation length and its frequency. Surface topography and morphology were analyzed on the AAJ-machined composite kerf wall cut surfaces. The machined surface exhibited the inherent characteristics of AAJ which included wear tracks, and contamination generated in the metal surface. The experimental results revealed that higher abrasive flow rate (400 g/min), lower traverse rate (30 mm/min), and higher aqua jet pressure (300 MPa), the production of a higher material removal rate, lower surface roughness and kerf taper angle.     

Multivariate Adaptive Regression Splines Model to Predict Fracture Characteristics of High Strength and Ultra High Strength Concrete Beams

This paper presents Multivariate Adaptive Regression Splines (MARS) model to predict the fracture characteristics of high strength and ultra high strength concrete beams. Fracture characteristics include fracture energy (GF), critical stress intensity factor (KIC) and critical crack tip opening displacement (CTODc). This paper also presents the details of development of MARS model to predict failure load (Pmax) of high strength concrete (HSC) and ultra high strength concrete (UHSC) beam specimens. Characterization of mix and testing of beams of high strength and ultra strength concrete have been described. Methodologies for evaluation of fracture energy, critical stress intensity factor and critical crack tip opening displacement have been outlined. MARS model has been developed by establishing a relationship between a set of predicators and dependent variables. MARS is based on a divide and conquers strategy partitioning the training data sets into separate regions; each gets its own regression line. Four MARS models have been developed by using MATLAB software for training and prediction of fracture parameters and failure load.MARS has been trained with about 70% of the total 87 data sets and tested with about 30% of the total data sets. It is observed from the studies that the predicted values of Pmax, GF, KIC and CTODC are in good agreement with those of the experimental values.