3D MHD cross flow over an exponential stretching porous surface

The present study aims to investigate the effects of thermal‐diffusion and diffusion‐thermo onan magnetohydrodynamic convective flow of viscous fluids over an exponentially stretching sheet. Thermal radiation effects are also considered in the study. This analysis is carried out in three dimensions and a similarity transformation is adopted to get a set of ordinary differential equations from a set of partial differential equations. And the Fourth‐order Runge‐Kutta method and shooting technique along with the secant method are employed to find out an iterative solution. We also analyze here the influence of the variable magnetic field, nonuniform permeability and variable chemical reaction on the fluid flow. The impact of various pertinent parameters of interest has extensively been explored through graphs and tables. The major findings of the present study are that resistive Lorentz force diminishes the fluid velocity and uplifts the thermal as well as concentration fields. Inclusion of porous matrix improves the viscous drag force which in turn augments wall shear stresses and peters out the heat and mass transfer rates from the sheet. In addition, the thermal expansion coefficient has an inverse relation with temperature.     

Analysis of hard turning process:thermal aspects

In manufacturing sector,hard turning has emerged as a vital machining process for cutting hardened steels.Besides many advantages of hard turning operations,one has to implement to achieve close tolerances in terms of surface finish,high product quality,reduced machining time,low operating cost and environmental friendly characteristics.In the study,three dimensional(3D) computer aided engineering(CAE) based simulation of hard turning by using commercial software DEFORM 3D has been compared to the experimental results of stresses,temperatures and tool forces in machining of AISI D3 and AISI H13 steel using mixed ceramic inserts(CC6050).In the following analysis,orthogonal cutting models are proposed,considering several processing parameters such as cutting speed,feed and depth of cut.An exhaustive friction modelling at the tool-work interface is carried out.Work material flow around the cutting edge is carefully modelled with adaptive re-meshing simulation capability of DEFORM 3D.The process simulations are performed at constant feed rate(0.075 mm/r) and cutting speed(155 m/min),and analysis is focused on stresses,forces and temperatures generated during the process of machining.Close agreement is observed between the CAE simulation and experimental values.     

Wear of Plasma Sprayed Conventional and Nanostructured Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and Cr<Subscript>2</Subscript>O<Subscript>3</Subscript>, Based Coatings

An ever increasing demand for high-performance ceramic coatings has made it inevitable for developing techniques with precise control over the process parameters to enable the fabrication of coatings with the desired microstructure and improved structural properties. The literature on plasma sprayed nanostructured ceramic coatings such as of Al₂O₃, Cr₂O₃, and their composites obtained using reconstituted nano sized ceramic powders has been reviewed in this study. Ceramic coatings due to their enhanced properties are on the verge of replacing conventional ceramic coatings used for various applications like automotive systems, boiler components, power generation equipment, chemical process equipment, aircraft engines, pulp and paper processing equipment, land-based and marine engine components, turbine blades etc. In such cases, the advantage is greater longevity and reliability for realizing the improved performance of ceramic coatings. It has been observed that the plasma sprayed nanostructured ceramic coatings show improvement in resistance to wear, erosion, corrosion, and mechanical properties as compared to their conventional counterparts. This article reviews various aspects concerning the plasma sprayed ceramic coatings such as (i) the present understanding of formation of plasma-spray coatings and factors affecting them, (ii) wear performance of nanostructured Al₂O₃, Cr₂O₃ and their composite ceramic coatings in comparison to their conventional counterparts, and (iii) mechanisms of wear observed for these coatings under various conditions of testing.     

Environmental radioactivity studies in the proposed Lambapur and Peddagattu uranium mining areas of Andhra Pradesh, India

The present work was aimed at the establishment of baseline radioactive data in the proposed Lambapur and Peddagattu uranium mining areas in the Andhra Pradesh state, India. The background concentrations of naturally occurring radioactivity in the near-surface soils of the study areas were estimated and the results were analysed. The (238)U concentration in the near-surface soil of the study area was found to vary from 100 to 176 Bq kg(-1), with a mean of 138±24 Bq kg(-1). (232)Th in the study area soils was found to vary between 64 and 116 Bq kg(-1), with a mean of 83±15 Bq kg(-1). The (40)K concentration was found to vary between 309 and 373 Bq kg(-1), with a mean of 343±20 Bq kg(-1). The mean natural background radiation levels were also measured with thermoluminescence (TL) dosimetry technique and with a μR-survey meter, in the villages of the study area. Dose rates measured by TL are found to vary from 1287 to 3363 μGy y(-1), with a mean of 2509 ± 424 μGy y(-1). The dose rates measured in the same villages with a μR-survey meter were found to be in the range of 1211-3255 μGy y(-1), with a mean of 2524 ± 395 μGy y(-1). The mean radiation levels in the study area are found to be relatively high when compared with (Indian) national and international averages. Correlations among radon, thoron and gamma dose rates were found to be poor. The pre-operational data produced in this work will be useful for comparison with future radiation levels during the proposed uranium mining operations.     

Electrochemically synthesized nanocrystalline spinel thin film for high performance supercapacitor

Spinels are not known for their supercapacitive nature. Here, we have explored electrochemically synthesized nanostructured NiCo₂O₄ spinel thin-film electrode for electrochemical supercapacitors. The nanostructured NiCo₂O₄ spinel thin film exhibited a high specific capacitance value of 580 F g⁻¹ and an energy density of 32 Wh kg⁻¹ at the power density of 4 kW kg⁻¹, accompanying with good cyclic stability.     

Antibacterial properties of silk fabric treated with Aloe Vera and silver nanoparticles

Silk is one of the important textile fibres used in apparel application. Since it is hygroscopic proteinous fibre, it is affected by microbes during usage and storage. Hence, antimicrobial treatment is desired to contain with this problem. Antimicrobial treatment is done using natural and synthetic agents. Nanoparticles have been added as antimicrobial agent for the application. In the present work, composite treatment of silk with Aloe Vera– a natural product and silver nanoparticles is done through crosslinking of 1,2,3,4-butane tetra carboxylic acid (BTCA) with silk in the presence of sodium hypophosphite (SHP). Effect of varying the concentration of BTCA, Aloe Vera and silver nanoparticles has been investigated. Untreated and treated silk fabrics have been characterized by FTIR, SEM and XRD to elucidate the effect of the treatment in terms of binding of Aloe Vera and silver nanoparticles, morphological changes and degree of crystallinity. Mechanical properties have been evaluated and analysed to illustrate the effect of the treatment. Further, the antimicrobial properties of the treated samples were evaluated against S. aureus (gram positive) and K. pneumoniae (gram negative) bacteria and the antimicrobial activity is found to be excellent. In order to assess the durability of the treatment, dry-cleaning has been done and subsequently antimicrobial properties have been assessed. Treated silk fabric samples after dry-cleaning upto 5 cycles exhibited satisfactory antimicrobial activity indicating that the treatment is durable in all the recipes. It is inferred that Aloe Vera chemically binds with silk through BTCA crosslinking while silver nanoparticles get adhesively bound or entrapped in the fibre matrix resulting in durable antimicrobial activity.     

Processing of Alumina-Rich Iron Ore Slimes: Is the Selective Dispersion–Flocculation–Flotation the Solution We Are Looking for the Challenging Problem Facing the Indian Iron and Steel Industry?

Beneficiation of alumina rich iron ore slimes is a major challenge for the Indian iron ore industry. Considering the limits of gravity and magnetic separation processes in the relatively finer size range in terms of achieving adequate separation efficiency, selective flotation (with and without selective flocculation) of iron ore slimes, which is being used commercially in several countries for the beneficiation of iron ores, is worth exploring for the beneficiation of Indian iron ores. Based on the extensive work carried out in our laboratories, we have concluded that the design and development of highly selective reagents to achieve satisfactory separation of hematite and goethite from alumina containing minerals (gibbsite or kaolinite) in the ore and ore slimes, is the key to solving the challenging problem of processing alumina rich iron ores. Accordingly our research work has been focused on finding/designing selective reagents for iron oxide–gibbsite–kaolinite separation based on a molecular modeling computational approach developed by us for the design of mineral processing reagents. We present in this paper the results of our density functional theory computations to evaluate the interaction energies of a wide variety of different reagent functional groups such as carboxylic acid, hydroxamic acid, phosphonic acid, iminobismethyl phosphoric acid, xanthate and starch with hematite, gibbsite and kaolinite surfaces. Among all the reagents investigated so far, starch exhibits the highest selectivity towards the hematite surface with a difference in interaction energy of ~63 kcal/mol between hematite and gibbsite surfaces. Based on our earlier work which indicated polyvinyl pyrrolidone (PVP) to be more selective dispersant for kaolinite compared to conventional sodium silicate and sodium hexametaphosphate, we have investigated selective flocculation–dispersion of natural iron ore slimes (three different samples obtained from three different mines in India) with PVP and starch reagent combination. The results are promising. While the work is still in progress, the implications of our recent results are discussed in the context of the challenging problem of processing of alumina rich iron ore slimes in India.     

Supply chain risk management and its mitigation in a food industry

We create a model which analyses the various risks involved in a food supply chain with the help of interpretive structural modelling (ISM). The various types of risks were identified based on a review of the literature and in consultation with experts in the food industry. The types of risks are clustered into five categories and risk mitigation is discussed. The model developed is validated with the help of a case study involving a food products manufacturing firm.     

The effect of processing conditions on microstructure of Pd-containing activated carbon fibers

Palladium-doped activated carbon fibers are being evaluated as candidate materials for enhanced hydrogen storage at near ambient conditions. Pd-doped fibers were spun using a Pd salt mixed with an isotropic pitch precursor. Experimental techniques such as in situ X-ray analysis, thermogravimetric studies, scanning transmission electron microscopy and gas adsorption were employed to understand how processing conditions for the production of Pd-doped activated carbon fibers affect the microstructure, pore development, and dispersion of metal particles throughout the fibers. The results showed that PdO phase is present in the stabilized fibers and that this oxide phase is stable up to about 250 °C. The oxide phase transforms into Pd metal with increasing heat treatment temperature, going through the formation of an intermediate carbide phase. Sintering of Pd particles was observed with heat treatment at temperatures over 750 °C. It was also found that pore development during physical activation with CO₂ was not significantly affected by the presence of Pd particles within the fibers.