Analysis of tunneling currents in multilayer black phosphorous and $$\hbox {MoS}_{2}$$ non-volatile flash memory cells

This paper presents a theoretical study of tunneling current density and the leakage current through multi-layer (stacked) trapping layer in the gate dielectric in MOS non-volatile memory devices. Two different 2D materials (\(\hbox {MoS}_{2}\) and black phosphorous) with a combination of high-k dielectric (\(\hbox {HfO}_{2}\)) have been used for the study with differently ordered stacks i.e., as trapping layer and substrate. The material properties of 2D materials like density of states, effective mass and band structure has been evaluated using density functional theory simulations. Using the Maxwell–Garnett effective medium theory we have calculated the effective barrier height, effective bandgap, effective dielectric constant and effective mass of the gate dielectric stacks. By applying WKB approximation in the multi-layer trapping layer we have studied the effect of the direct and Fowler–Nordheim tunneling currents. The leakage current in all the different stack combinations used has also been evaluated. The results obtained have shown to match the required dynamics of a memory device.     

Synthesis and characterization of Ni-Mo catalyst using Jatropha curcas leaves as carbon support and its catalytic activity for hydrotreating of gas oil,Jatropha oil,and their blends

A novel carbon-based Ni-Mo catalyst has been synthesized successfully from Jatropha curcas leaves using boric acid as a surface modifying agent. The Ni-Mo catalyst prepared on Jatropha curcas leaves had shown BET surface area of 316 m²/g whereas the Ni-Mo catalyst prepared without boric acid activation had shown BET surface area of only 14 m²/g. XRD and SEM data have shown that the active catalyst particles such as Ni and Mo have been found to be uniformly distributed. The inventive catalyst was studied for hydrotreating of gas oil, Jatropha curcas oil and 20% Jatropha oil in gas oil at 370°C, 90 bar H₂ pressure, liquid hour space velocity of 1 h^?1, and gas-to-oil ratio of 500 Nm³/m³ and the results obtained were found to be comparable with that of the commercial Ni-Mo catalyst supported on alumina.     

An empirical correlation for estimating the viscosity of non-Newtonian waxy crude oils

Non-Newtonian fluids are the most complex ones when it comes to predicting their flow behavior. In the pre-existing models, rheological behavior in waxy crude oils is mainly affected by shear rate and thermal history of crude oils. In the present work, rheological characteristics of four different crude oils were studied by coaxial cylindrical rheometer at three different temperatures (40°C, 50°C, and 60°C) and a model was proposed keeping into consideration wax content for the first time. This model is prepared to predict the viscosity of four different crude oils with different wax content and at different temperature. The proposed model can efficiently estimate the viscosity as compared to other established models.     

PF-ID-2PAKA: Pairing Free Identity-Based Two-Party Authenticated Key Agreement Protocol for Wireless Sensor Networks

Wireless Personal Communications - To ensure secure communication between any two entities, authenticated key agreement protocol is the primary step and current research has a lot of contribution...     

Channel capacity with suboptimal adaptation technique over generalized-K fading using marginal moment generating function

In this paper we have computed the channel capacity for suboptimal adaptation technique over the generalized-K fading environment. The analytical expression for channel capacity in case of the truncated channel inversion with fixed rate (C_TCIFR) has been exploited in terms of marginal moment generating function (MMGF) and its performance is evaluated over the generalized-K faded environment. The MMGF based approach for the computation of channel capacity has been validated with the reported literature for channel capacity in case of the channel inversion with fixed rate using the suboptimal adaptive technique.     

Morphologies of Sol–Gel Derived Thin Films of ZnO Using Different Precursor Materials and their Nanostructures

We have shown that the morphological features of the sol–gel derived thin films of ZnO depend strongly on the choice of the precursor materials. In particular, we have used zinc nitrate and zinc acetate as the precursor materials. While the films using zinc acetate showed a smoother topography, those prepared by using zinc nitrate exhibited dendritic character. Both types of films were found to be crystalline in nature. The crystallite dimensions were confined to the nanoscale. The crystallite size of the nanograins in the zinc nitrate derived films has been found to be smaller than the films grown by using zinc acetate as the precursor material. Selected area electron diffraction patterns in the case of both the precursor material has shown the presence of different rings corresponding to different planes of hexagonal ZnO crystal structure. The results have been discussed in terms of the fundamental considerations and basic chemistry governing the growth kinetics of these sol–gel derived ZnO films with both the precursor materials.

Turbulent natural convection in an enclosure with localized heating from below

This study reports the results of a numerical investigation of turbulent natural convection in a square enclosure with localized heating from below and symmetrical cooling from the vertical side walls. The present study simulates the case of an accidental heat generation due to fire in a typical isolated building of a nuclear reactor or electronic components cabin. The source of fire is considered to be centrally located at the bottom wall with different heated widths, which is assumed to be either isothermal or with isoflux. For the purpose of the analysis, the source length is varied from 20 to 80% of the total width of the bottom wall. The top wall and the unheated portion of the bottom wall are considered to be adiabatic, whereas sidewalls are isothermal. Steady as well as transient forms of two-dimensional Reynolds–Averaged-Navier–Stokes equations and conservation equations of mass and energy, coupled with the Boussinesq approximation, are solved by the control volume based discretisation method employing the SIMPLE algorithm for pressure–velocity coupling. Turbulence is modeled using the standard k–ε model. Rayleigh number, Ra, based on the enclosure height is varied from 10⁸ to 10¹². Stream lines and isotherms are presented for various combinations of Ra and the heated width. A double cell flow pattern is observed with marginal loss in symmetry as Ra increases. The results are reported in the form of local and average Nusselt number on the heated floor. Correlations are developed to predict the heat transfer rates from the enclosure as a function of dimensionless heated width of the bottom wall and Ra, by least square linear regression analysis.     

In situ observations of catalyst dynamics during surface-bound carbon nanotube nucleation

We present atomic-scale, video-rate environmental transmission electron microscopy and in situ time-resolved X-ray photoelectron spectroscopy of surface-bound catalytic chemical vapor deposition of single-walled carbon nanotubes and nanofibers. We observe that transition metal catalyst nanoparticles on SiOx support show crystalline lattice fringe contrast and high deformability before and during nanotube formation. A single-walled carbon nanotube nucleates by lift-off of a carbon cap. Cap stabilization and nanotube growth involve the dynamic reshaping of the catalyst nanocrystal itself. For a carbon nanofiber, the graphene layer stacking is determined by the successive elongation and contraction of the catalyst nanoparticle at its tip.