Sustainable Drilling of Nano SiC Reinforced Al Matrix Composites Using MQL and Cryogenic Cooling for Achieving the Better Surface Integrity

Silicon - Metal Matrix Nano Composites (MMNCs) are progressive alternatives of formal metal materials, are presently accomplishing a growing inclination of research and engineering approaches for...     

Development of topical gel containing aceclofenac-crospovidone solid dispersion by “Quality by Design (QbD)” approach

This article describes the development, optimization, and evaluation of Carbopol 940 topical gel containing aceclofenac-crospovidone (1:4) solid dispersion using “Quality by Design (QbD)” approach based on 2³ factorial design. The effect of crospovidone, tri-ethanolamine, and ethyl alcohol amount on the drug permeation profile of the topical gel containing aceclofenac-crospovidone solid dispersion was optimized by 2³ factorial design. The optimized gel showed improved permeation profile with cumulative drug permeation of 26.262 ± 2.157%, and permeation flux of 0.059 ± 0.011 μg/cm²/h. These gels were characterized by pH, viscosity, gel strength and FTIR study. The in vivo anti-inflammatory activity of the optimized gel was evaluated in rats using carrageenan-induced rat-paw oedema model and found excellent anti-inflammatory comparable with a marketed gel without producing any skin irritation.     

Impact of zonal wind on latitudinal variation of total columnar ozone over the Indian Peninsula

Latitudinal and seasonal variability of total columnar ozone from September 2007 to August 2008 across the Indian longitude sector within 10.5° N to 34.5° N and 70.5° E to 94.5° E using satellite data obtained from Aura Ozone Monitoring Instrument (OMI) of National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) is presented. The total column ozone (TCO) over the area of study shows a gradually varying pattern throughout the year. In the post-monsoon (autumn) and winter months, maximum TCO is observed in the north-western part of the subcontinent while the minimum is often observed towards the east at about the same latitudes. A west–east spatial gradient is clearly observed in autumn months. As winter approaches, a north–south spatial gradient becomes more prominent than the east–west gradient. It has been further observed that TCO does not vary significantly over the entire subcontinent in monsoon.     

A computer simulation approach to evaluating bowl versus inverted bowl assembly line arrangement with variable operation times

A computer simulation model was used to evaluate a bowl versus inverted bowl assembly line arrangement for normal and exponential distributions and variances equal to 1 and 16. The model was developed on the basis of a realistic case problem and applied to a six-station assembly line. The results show that the inverted bowl is superior to the bowl arrangement for a normal distribution in terms of the total elapsed time evaluation criterion; however, with an exponential distribution, the bowl was found better than the inverted bowl for the same criterion. On the basis of the average percentage of working time and the average time in the system evaluation criteria, the bowl was found superior to the inverted bowl for a normal distribution. Similar results were obtained for an exponential distribution with a variance equal to 1, but no definitive inference could be made with a variance equal to 16.     

Security enforcement in wireless sensor networks: A framework based on non-cooperative games

This paper focuses on the design of security enforcement mechanisms for the prevention of denial of service (DoS) attacks in wireless sensor networks. In the first part, we identify the requirement for security enforcement using auction theory, which allows us to detect non-cooperative nodes. Our novel scheme for preventing DoS attacks is called Secure Auction based Routing (SAR). In the proposed protocol, nodes prefer to participate in forwarding incoming packets and gaining reputation in the network. Nodes willing to do so must compete against each other, and the competition is based on auction theory. The amount of bid that each node offers is equal to its utility value; and the price that a winner of a bid pays is a reduction in its original battery power. Since a node’s truthful bidding is shown to be a dominant strategy, in order to prevent DoS attack, nodes that do not bid truthfully should be isolated.In the second part, we formulate the attack–defense problem as a non-cooperative, two-player, non-zero-sum game between an attacker and a wireless sensor network. We show that this game achieves Nash equilibrium, thus leading to a defense strategy for the network. We propose two novel schemes. The first one is called Utility based Dynamic Source Routing (UDSR), which incorporates the total utility of each en-route node in data packets, where utility is the difference between gain and cost for each node. The second scheme is based on a watch-list, where each node earns a rating from its neighbors, based on its previous cooperation in the network. Simulation results show that the proposed game theoretic framework significantly increases the chance of success in defense strategy for the wireless sensor network.     

Estimation of Elastic Properties of Porous Ceramic Using Ultrasonic Longitudinal Wave Velocity Only

A method for estimation of the elastic moduli of porous ceramics solely based on ultrasonic longitudinal wave velocities is proposed. The method is based on a polynomial correlation between ultrasonic shear wave and longitudinal wave velocities of a given porous material. It is also shown that variations of Poisson's ratios for porous material with longitudinal wave velocities agree with the predictions of Mori-Tanaka mean field approach. The method provides a simplified route to quantitative non-destructive evaluation of the elastic moduli of porous material.     

Synthesis and Characterization of Nanoparticles,Nanotubes, Nanopans,and Graphene-like Structures of Boron Nitride

By heating H₃BO₃ with urea in 1 : 6 molar ratio, nanoparticles and nanotubes of BN are obtained. The urea–boric acid reaction can also be exploited to obtain graphene analogues of BN, with the number of layers depending on the relative proportions of the two reactants. Synthesis with a high proportion of urea yields a product containing graphene analogues of BN with an average of 2 layers. The surface area of BN increases with the decreasing number of layers, and the high-surface-area BN also exhibits high CO₂ adsorption. Few-layer BN can be solubilized by interaction with Lewis bases. Nanopans and nanosheets formed by graphene-like BN are generated by the vapor phase reaction of NH₃ and BBr₃ at 1223 K. Nanopans of BN, being reported for the first time, have a bottom comprising single-layer BN and a wall of 0.7 nm height. The average inner volume of the nanopan is around 400 nm³.     

151Eu Mössbauer studies on Zn-doped EuBa2Cu3O7−y

¹⁵¹Eu Mössbauer studies have been performed on the compounds EuBa₂(Cu_1?x Zn _x )₃O_7?y withx=0·0, 0·025, 0·05, 0·075 and 0·1. The parent compound, EuBa₂Cu₃O_7?y is superconducting with a transition temperature (T _c ) of 88 K.T _c is depressed as Zn is substituted for Cu in this system and the compounds withx>0·05 do not show superconductivity down to 12 K.¹⁵¹Eu Mössbauer studies at 295 K show a single Mössbauer line in all the compounds (whether superconducting or not) with isomer shift value typical of Eu^{3 +} ion. Further, the isomer shift values are nearly independent ofx and the temperatures down to 10 K. These observations imply that the Cu-O network responsible for superconductivity is very weakly coupled to the Eu sublattice.