Experimental investigation on wire electric discharge machining (WEDM) of Nimonic C-263 superalloy

Nimonic C-263 superalloy offers a wide range of outstanding properties, namely, high-temperature resistance, high specific strength, high thermal fatigue, and hot corrosion resistance. The concern of the present study is mainly focused on the effect of wire electrical discharge machining (WEDM) process parameters namely, spark energy, spark frequency, and peak current on surface roughness, average cutting rate, and surface integrity aspects of Nimonic C-263 superalloy by using one-parameter-at-a-time (OPAT) approach. Surface roughness and average cutting rate were showing the increasing trend with the spark energy and peak current and reverse trend with the spark frequency. Surface integrity aspects of Nimonic C-263 such as surface topography, surface morphology, recast layer thickness, elemental composition, and phase analysis have been also considered in this study. Scanning electron microscope (SEM) micrograph of the machined surface shows the presence of micro-voids, discharge craters, micro-globules, and droplets of molten material. A recast layer of minimum thickness, with less transfer of foreign atoms (Mo, C, and O) from dielectric fluid and molybdenum wire, has been formed at lower spark energy compared to higher spark energy. The various compounds of Ni, Fe, Al, and Ti such as Fe_1.2Ni_0.8, Fe_1.5Ni_0.5, Co_0.06Fe_0.94, and Al_o.29Ni_0.27Ti_0.44 were formed on the machined surface identified through analysis of XRD peaks.     

Modelling time-dependent aggregate traffic in 5G networks

Telecommunication Systems - Future wireless networks like 5G will carry an increasingly wide variety of data traffic, with different QoS requirements. In addition to conventional data traffic...     

Anthracene removal from water onto activated carbon derived from vehicular tyre

The present study focuses on adsorptive removal of anthracene by application of activated carbon developed from waste vehicular tyres (VTAC). Different experimental parameters were varied to examine their influence on anthracene adsorption. The results reveal that concentration of anthracene in aqueous phase reduces continuously with enhancement in shaking time. After a period of 75 min, the adsorption of anthracene on VTAC was observed to be in equilibrium. The adsorption of anthracene was >99% in presence of 14–20 mg and an adsorbent dose of 8 mg was used to analyse the effect of other parameters in the present study. As pH of solution is lowered, rise in adsorption capacity of VTAC was observed. The obtained data were applied to Langmuir and Freundlich isotherms for studied PAH adsorption. The second order kinetics was suggested to be better fitted with R² values >0.95. Intra-particle diffusion and Boyd-Reichenberg model were applied for investigating the mechanism of adsorption.     

Numerical study of activation energy and thermal radiation effects on Oldroyd-B nanofluid flow using the Cattaneo–Christov double diffusion model over a convectively heated stretching sheet

This paper investigates a theoretical model of a mixed convective Oldroyd-B nanofluid with thermal radiation and activation energy effects. A thorough analysis is done by employing the nonhomogeneous Buongiorno model in the presence of velocity slip and suction. The surface is porous in nature, and nanoparticle mass flux is maintained passively at the surface. The thermal and concentration equations are modeled with the Cattaneo–Christov theory of heat and mass flux, respectively. Proper transformations are utilized for the conversion of transport equations and boundary conditions. The similarity solution is obtained through a numerical approach by utilizing the Runge–Kutta–Fehlberg method and shooting technique. The vital outcomes of this study and the influence of controlling parameters on the flow field, temperature, and concentration profiles are discussed graphically and in a tabular manner. Furthermore, a detailed discussion is provided to explain the results physically. The velocity of the nanofluid increases when the porosity parameter is increased, and temperature decreases with increasing thermal relaxation parameter. The outcomes elucidate that the suction parameter, thermal radiation parameter, and thermal relaxation parameter are positively correlated with the heat transfer coefficient. The result of passive control of nanoparticles at the surface is that the Brownian motion parameter has no influence on the temperature of the Oldroyd-B nanofluid flow and rate of heat transfer at the surface.     

Numerical solution for Sisko nanofluid flow through stretching surface in a Darcy–Forchheimer porous medium with thermal radiation

The heat transfer assessments in a Sisko nanofluid flow over a stretching surface in a Darcy–Forchheimer porous medium with heat generation and thermal radiation are studied. The numerical analysis technique is used to assess the governing nonlinear equations of the model. The influence of Forchheimer number, porosity, heat generation, radiation, and material parameters is examined. The outlines of Nusselt number and skin friction coefficient corresponding to pertinent parameters are revealed. The comparison of Nusselt number outlines of working fluid and Newtonian fluid is depicted. From the analysis, it has been examined that with the increase in Forchheimer number and material parameter values, heat transfer function decreases, whereas heat transfer characteristics of Sisko nanofluid increase with heat generation and material parameters. Moreover, working fluid velocity outlines depreciate when there is an increase in porosity parameter for both shear-thinning and shear-thickening. The comparison of this study with previous research has been conducted.     

YOLOv4 algorithm for the real-time detection of fire and personal protective equipments at construction sites

Multimedia Tools and Applications - Many difficulties are encountered during evacuation from construction sites in hazardous situations, which may lead to severe fatalities. These fatalities,...     

An Improved Attention and Hybrid Optimization Technique for Visual Question Answering

Neural Processing Letters - In Visual Question Answering (VQA), an attention mechanism has a critical role in specifying the different objects present in an image or tells the machine where to...     

Optimum Trans–Receiver Scheme Using Cross Layer Design for Acoustic Communication

The main objective of this work is to reduce the packet loss due to packet error rate and buffer overflow for under water sensor network. In this work, a system is mapped into various states based on channel condition, buffer space, and available energy level. The set of policies are defined in terms of transmission power level, adaptive modulation scheme, and various transmission rate. We have proposed Optimum Trans–Receiver Scheme (OTRS), in which the problem is formulated as per Markov decision process model and solution is sought in terms of optimum policy identification for an individual state of the system. We have evaluated the performance of OTRS by extensive simulation with existing Adaptive Modulation Power Adaption, Power Adaption with 2 Ary Frequency Shift Keying and Power Adaption with 8 Ary Frequency Shift Keying for various performance matrices like Net Bit Rate and number of packet loss for various state of the system.

     

Nanoindentation behaviour of nano BiFeO3

Bismuth ferrite (BiFeO₃) is a unique magnetoelectric multiferroic that exhibits the coexistence of ferroelectricity and antiferromagnetism at room temperature. This unique combination of properties has pumped a huge surge in current research on BiFeO₃ as a future material for very important technological applications such as magnetic detectors and as an active layer in magnetoelectric memories. For such applications involving miniaturized components and devices, it is essentially important to have an idea of the mechanical integrity of the system at the scale of the microstructure. In spite of the wealth of the literature, however, the attempt to evaluate the mechanical integrity of nano BiFeO₃ at a scale comparable with the local microstructural length scale was almost non-existent. Here we report, possibly for the first time the nanoindentation behaviour of a sol-gel process derived nano BiFeO₃ having particle size of 5-25 nm. The nanoindentation studies were conducted at 100-1000 μN loads on a green pellet annealed at a low temperature of only 300 °C to avoid particle coarsening. The results showed interesting dependence of nanohardness and Young's modulus on the nanoindentation load which could be explained in terms of elastic recovery and plastic deformation energy concepts.