Theoretical Investigation of Magnetohydrodynamic Radiative Non-Newtonian Fluid Flow over a Stretched Surface

The aim of this study is to investigate the heat and mass transfer in magnetohydrodynamic Newtonian and non-Newtonian fluid flow over a stretched domain in the presence of thermal radiation, chemical reaction, Soret and Dufour effects. In addition to this, we also considered the aligned magnetic field (i.e. the magnetic field applied at different angles) along the flow direction and dual solutions are executed for the transverse and aligned magnetic field cases. The governing system of equations is transformed as the system of ODEs with the help of suited similarity transforms. The resulting equations are solved numerically with the aid of the shooting process. The graphical and tabular results are explored to discuss the flow, thermal and concentration behavior along with the heat and mass transfer rate. Keywords: MHD, Aligned Magnetic field, Soret and Dufour effects, Radiation, Chemical reaction

Magneto Hydrodynamic Flow of Dissipative Non-Newtonian Fluid over an Exponential Stretching Surface with Thermal Radiation

Numerical investigation is carried out to analyze the flow, heat and mass transfer behavior of magnetohydrodynamic non-Newtonian fluid (Casson) over a stretched surface with thermal radiation, chemical reaction and viscous dissipation effects. The governing PDEs are transformed as ODEs with the help of suited similarity transform. The effective Matlab package bvp5c is used to obtain the numerical solutions of the transformed equations. The impact of pertinent parameters on the common profiles (flow, temperature and concentration) is discussed in detail with the assistance of graphical illustrations for Casson and Newtonian fluid cases. Tabular results are presented to explain the nature of the wall friction, local Nusselt and Sherwood numbers. Keywords: Magnetohydrodynamics; Radiation; Dissipation; Casson; Chemical reaction

VLSI Implementation of Encoder and Decoder for Advanced Communication Systems

Forward Error Correction (FEC) schemes are an essential component of wireless communication systems.Present wireless standards such as Third generation (3G) systems, GSM, 802.11A, 802.16 utilize some configuration of convolutional coding. Convolutional encoding with Viterbi decoding is a powerful method for forward error correction. The Viterbi algorithm is the most extensively employed decoding algorithm for convolutional codes which comprises of minimum path and value calculation and retracing the path. The efficiency of error detection and correction increases with constraint length. In this paper the convolutional encoder and viterbi decoder are implemented on FPGA for constraint length of 9 and bit rate ½

Energy optimization of 6T SRAM cell using low-voltage and high-performance inverter structures

The performance of the cell deteriorates, when static random access memory (SRAM) cell is operated below 1V supply voltage with continuous scale down of the complementary metal oxide semiconductor (CMOS) technology. The conventional 6T, 8T-SRAM cells suffer writeability and read static noise margins (SNM) at low-voltages leads to degradation of cell stability. To improve the cell stability and reduce the dynamic power dissipation at low- voltages of the SRAM cell, we proposed four SRAM cells based on inverter structures with less energy consumption using voltage divider bias current sink/source inverter and NOR/NAND gate using a pseudo-nMOS inverter. The design and implementation of SRAM cell using proposed inverter structures are compared with standard 6T, 8T and ST-11T SRAM cells for different supply voltages at 22-nm CMOS technology exhibit better performance of the cell. The read/write static noise margin of the cell significantly increases due to voltage divider bias network built with larger cell-ratio during read path. The load capacitance of the cell is reduced with minimized switching transitions of the devices during high-to-low and low- to-high of the pull-up and pull-down networks from VDD to ground leads to on an average 54% of dynamic power consumption. When compared with the existing ones, the read/write power of the proposed cells is reduced to 30%. The static power gets reduced by 24% due to stacking of transistors takes place in the proposed SRAM cells as compare to existing ones. The layout of the proposed cells is drawn at a 45-nm technology, and occupies an area of 1.5 times greater and 1.8 times greater as compared with 6T-SRAM cell

Ab initio Molecular Dynamical Investigation of the Finite Temperature Behavior of the Tetrahedral Au19_{19} and Au20_{20} Clusters

Density functional molecular dynamics simulations have been carried out to understand the finite temperature behavior of Au$_{19}$ and Au$_{20}$ clusters. Au$_{20}$ has been reported to be a unique molecule having tetrahedral geometry, a large HOMO-LUMO energy gap and an atomic packing similar to that of the bulk gold (J. Li et al., Science, {\bf 299} 864, 2003). Our results show that the geometry of Au$_{19}$ is exactly identical to that of Au$_{20}$ with one missing corner atom (called as vacancy). Surprisingly, our calculated heat capacities for this nearly identical pair of gold cluster exhibit dramatic differences. Au$_{20}$ undergoes a clear and distinct solid like to liquid like transition with a sharp peak in the heat capacity curve around 770 K. On the other hand, Au$_{19}$ has a broad and flat heat capacity curve with continuous melting transition. This continuous melting transition turns out to be a consequence of a process involving series of atomic rearrangements along the surface to fill in the missing corner atom. This results in a restricted diffusive motion of atoms along the surface of Au$_{19}$ between 650 K to 900 K during which the shape of the ground state geometry is retained. In contrast, the tetrahedral structure of Au$_{20}$ is destroyed around 800 K, and the cluster is clearly in a liquid like state above 1000 K. Thus, this work clearly demonstrates that (i) the gold clusters exhibit size sensitive variations in the heat capacity curves and (ii) the broad and continuous melting transition in a cluster, a feature which has so far been attributed to the disorder or absence of symmetry in the system, can also be a consequence of a defect (absence of a cap atom) in the structure.Comment: 7 figure

Structural Analysis and Optimization of Nozzle Attachment on Channel Shell Design

In Channel shells, Nozzles are required for inlet and outlet purposes either to carry fluids or for providing multipurpose connections. If these nozzles present on peak of the dish end do not disturb the symmetry of the shell. However sometimes process requires that nozzles to be placed on the periphery of the shell. These nozzles disturb the symmetry of the shell. Geometrical parameters of nozzle connections may significantly vary even in one channel shell. These nozzles cause geometric discontinuity of the shell wall. So a stress concentration is created at the junction. Hence a detailed analysis is required. If nozzles are placed on the periphery of a channel shell, they disturb the axis symmetry of the system and cause eccentricity. Sometimes this cause generation of a couple & lead to a structural imbalance. So that it need to analysed in FEA to understand effects of nozzle on Stress attributes of the shell. This work also studies the effect of eccentricity of the nozzles under varying thickness of shell and reinforcement pad. The effect of material concession for nozzle and Shell on the stress induced is also studied. From the results obtained by ANSYS, optimum study was performed by response surface methodology to obtain optimum shell thickness and reinforcement pad thickness for different class of materials

Relation between reversal dominance time and carrying capacities in multiplex ecological ammensalism - A numerical study

The paper aims to investigate a mathematical model of multiplex Ecological Ammensalism with the help of classical RK-method of fourth order in view of reversal dominance time. The mathematical model constitutes of Ammensal-enemy species pair with cover protection for Ammensal species, alternative resources for enemy species and both the species are immigrated. In addition to this, harvesting variable rates are also incorporated. The model is characterized by a couple of first order non linear ordinary differential equations. The relation between the carrying capacity of Ammensal /enemy species with the reversal dominance time is investigated numerically. Some conclusions are derived from the relationships.  AMS Classification: 92 D 25, 92 D 4

Stability of binary complexes of Pb(II), Cd(II) and Hg(II) with maleic acid in TX100-water mixtures

Binary complexes of maleic acid with toxic metal ions such as Pb(II), Cd(II) and Hg(II) have been studied in 0.0-2.5% v/v tritonX-100 (TX100) - water media at 303 K  at an ionic strength of 0.16 M. The active forms of the ligand are LH2, LH- and L2-. The derived ‘best fit’ chemical speciation models are based on crystallographic R-factors, χ2 and Skewness and Kurtosis factors. The predominant species formed are of the type ML2, ML2H and ML3. The trend in variation of complex stability constants with change in the mole fraction of the medium is explained on the basis of prevailing electrostatic and non-electrostatic forces. The species distribution as a function of pH at different compositions of TX100-water mixtures and plausible speciation equilibria are presented and discussed. KEY WORDS: Maleic acid, TritonX-100, Toxic metal ions, Mole fraction, Binary complexes Bull. Chem. Soc. Ethiop. 2014, 28(3), 383-391.DOI: http://dx.doi.org/10.4314/bcse.v28i3.

A Rare Association of Giant Cell Arteritis with Recurrent Corneal Ulcer

We report a rare case of association of temporal arteritis with recurrent central corneal ulcer. A 91-year-old male with a remote history of clinically diagnosed giant cell arteritis (GCA) and penetrating keratoplasty (PK) for corneal edema in 1990’s in the left eye presented with irritation and severe dry eye. He progressively developed central corneal ulcer regardless of treatment with aggressive lubrication and patching. The clinical course, blood tests and temporal artery biopsy results yielded the diagnosis of recurrent GCA. The clinical course improved after starting oral steroids. The case report illustrates the importance of ruling out GCA in patients with recurrent corneal ulcers and history of GCA. It also highlights the significance of shared understanding between primary care physicians and specialists to handle common and chronic diseases to make efficient diagnoses and plan treatment regimens. This is the first plausible case of reported GCA association with central corneal ulcer in the United States