Magnetoconvection in a Square Enclosure with Sinusoidal Temperature Distributions on Both Side Walls

A computational study of convective flow and heat transfer in a cavity in the presence of uniform magnetic field is carried out. The side walls of the cavity have spatially varying sinusoidal temperature distributions. The horizontal walls are adiabatic. The governing equations are solved by the finite volume method. The results are discussed for different combinations of phase deviation, amplitude ratio, and Hartmann and Rayleigh numbers. It is observed that the heat transfer rate is increased with amplitude ratio. The heat transfer rate is increased first and then decreased on increasing the phase deviation. It is also found that the heat transfer rate is decreased with an increasing Hartmann number.     

Reversed signal propagation BDD based low‐power pass‐transistor logic synthesis

Binary decision diagrams (BDDs) are the most frequently used data structure for the representation and manipulation of Boolean functions in the area of Very Large Scale Integration (VLSI) CAD. In this paper, we propose the reversed‐signal‐propagation (RSP) BDD‐based low‐power pass‐transistor logic (PTL) synthesis. In RSP BDD, the signal flow direction is opposite to that of the forward BDD. So the power supply is taken as a root node and the terminal nodes 0 and 1 represent the function in its normal and complement form. We propose an efficient way to construct the multi‐output function RSP BDD and its PTL realization. Simulation results of the proposed method give lower power consumption and high performance as a result of reduced switching activity than the existing techniques. The power improvement is about 70–80% compared to the existing techniques. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

High-sensitivity, label-free DNA sensors using electrochemically active conducting polymers

Label-free oligonucleotide sensors that use a change in the electrode kinetics of the redox reaction of the negatively charged Fe(CN)(6)(3-/4-) redox couple to signal the formation of a DNA duplex with a surface-conjugated probe nucleotide are investigated. Electrochemically active conducting polymers (ECPs) can advantageously be used both as the active electrode and as the means of surface conjugation of the probe nucleotide. Here, we demonstrate that the sensitivity of the detection of the surface-complementary oligonucleotide can significantly be improved, into the low nanomolar range, by forming the ECP as a highly porous, very rough layer by growing it using electrochemical polymerization on a microelectrode. In comparison, smoother surfaces formed on macroelectrodes had detection sensitivity in the low micromolar range. We propose Donnan exclusion of the redox couple from small pores as the reason for the enhanced sensitivity. We discuss the effects using a simple patch model for the electrochemical kinetics and use the model to derive the equilibrium binding constant and binding kinetic rate constants for the surface hybridization reaction. We use the electrochemically active copolymer of pyrrole (Py) and 3-pyrrolylacrylic acid (PAA) [poly(Py-co-PAA)] as the sensing electrode and binding surface and measure the surface hybridization-induced changes in electrode kinetics of Fe(CN)(6)(3-/4-) by electrochemical impedance spectroscopy.     

An accurate and economical approach for induction motor field efficiency estimation using bacterial foraging algorithm

As the demand of electrical energy increases, it is vital to replace inefficient motors with new energy efficient ones. The first step towards achieving this goal is to estimate the existing motors efficiencies accurately to determine how much energy saving will be achieved by using energy efficient motors. This paper proposes an economical and accurate approach for motor field efficiency estimation using bacterial foraging algorithm. The approach relies on the measurement of the stator current, stator voltage, input power, stator resistance and rotor speed of the motor without conducting no-load and locked-rotor tests. The BF algorithm is used to determine the equivalent circuit parameters of the motor. The efficiency is then estimated using these parameters. The advantages of the proposed method over the existing methods are simple procedure, efficiency can be estimated accurately without conducting any invasive tests and inexpensive. The approach has been tested on a 5 HP motor and the results are compared with particle swarm optimization method, immune algorithm method, torque gauge method, equivalent circuit method, slip method, current method and segregated loss method. The results demonstrate that the proposed approach can accurately estimate the field efficiency of motor. Accordingly, it is suitable for conducting energy audits and management of the motor.     

Image analysis for detecting insect fragments in semolina

Semolina is used for the manufacture of pasta (long goods and short goods) and couscous and any contrasting colored specks adversely affect the appearance of the finished product. The specks result from wheat bran, diseased wheat, ergot or weed seeds. However, there is also the possibility that insect fragments will appear as specks. Specks are currently mostly determined by a manual process or by a speck counter in milling units. We compared the speck counts from an electronic speck counter (SPX Maztech Micrco Vision), acid hydrolysis and flotation (AOAC method 993.26), and near-infrared (NIR) hyperspectral imaging in semolina seeded with insect fragments (50-300 fragments/50 g) of Tribolium castaneum (Coleoptera: Tenebrionidae). There was a significant positive correlation between the number of insect fragments added and detected by all three methods. These results underline the importance of controlling insects in flour mills producing semolina, and also in plants producing pasta and couscous, to reduce speck counts in the finished products.     

Electrical characteristics of ZrN metallised metal-oxide-semiconductor and metal-insulator-metal devices

The electrical properties of DC reactive sputtered zirconium-nitride metallized metal-oxide-semiconductor (MOS) and metal-insulator-metal (MIM) devices on TiO₂/p-Si and TiO₂/ZrN films were studied using capacitance-voltage (C-V) and current-voltage (I-V) measurements at room temperature. Capacitances of the ZrN/TiO₂/p-Si MOS device were measured in accumulation mode and inversion mode, from which flat band capacitance was found to be 2.86pF, which corresponds to flat band voltage of −1.7 V. Fixed oxide charged density and interface state density was found to be 1.63× 10¹⁰ cm⁻² and 6.3× 10¹¹ cm⁻² eV⁻¹. I-V characteristics revealed that the leakage current density was of 0.5 mA/cm² in accumulation mode and 2 mA/cm² in inversion mode at a field of 0.12 MV/cm, respectively. Dielectric breakdown of ZrN/TiO₂/p-Si device was found to be 0.12 MV/cm in accumulation mode. Based on the C-V and I-V characteristics, the ZrN/TiO₂/ZrN structure showed no variation in the capacitance value as the bias voltage was changed.     

Interdependency Analysis of Inter-Site-Distance on Configuration of Handover Control Parameter in LTE-A HetNets

Wireless Personal Communications - Handover (HO) is the procedure performed to maintain the ongoing session of mobile User Equipment (UE). In Long Term Evolution-Advanced (LTE-A) network, the...     

Synthesis and Surface Modification of LiCo1/3Ni1/3Mn1/3O2 for Lithium Battery Applications

In an attempt to prepare phase-pure LiCo_1/3Mn_1/3Ni_1/3O₂ compound, the sol–gel method with precursors containing different ratios of lithium and transition-metal ions such as Li:M = 1:1, 1.05:1, 1.10:1, 1.15:1, 1.20:1, and 1.25:1 has been deployed. Properties such as phase purity, perfect layeredness, good cation ordering, and acceptable charge–discharge behavior were observed only when LiCo_1/3Ni_1/3Mn_1/3O₂ was prepared using a Li:M ratio of 1.15:1.0, leading to the recommendation of this as the optimum precursor ratio to prepare active LiCo_1/3Ni_1/3Mn_1/3O₂ cathodes for batteries. Further, with a view to suppress the capacity fade behavior of native LiCo_1/3Mn_1/3Ni_1/3O₂ cathodes observed in high-voltage (4.6 V) regions, selected HF-scavenging metal oxide (Al₂O₃) or metal hydroxide [Al(OH)₃] was deployed as a surface modifier. Interestingly, LiCo_1/3Ni_1/3Mn_1/3O₂ cathode modified with Al(OH)₃ exhibited significantly improved electrochemical properties such as lower charge-transfer resistance (42 Ω), higher specific capacity (158 mAh/g), and excellent capacity retention (99%). This study demonstrates the superiority of Al(OH)₃ over Al₂O₃ in modifying the electrochemical properties of native LiCo_1/3Ni_1/3Mn_1/3O₂ cathodes, as desired for practical lithium battery applications.     

Scanned Pipette Techniques for the Highly Localized Electrochemical Fabrication and Characterization of Conducting Polymer Thin Films,Microspots, Microribbons,and Nanowires

The limited toolbox for conducting polymer (CP) microscale fabrication and characterization hampers the development of applications such as sensors and actuators. To address this issue, a robust and integrated methodology is presented, capable of electrochemical fabrication and characterization of CPs in a highly localized manner, allowing for CP patterning and spatial mapping of voltammetric response. This is enabled by scanning probe microscopy (SPM) tipped with a single‐barreled micropipette to electrochemically polymerize CP microspot arrays, demonstrated for 3,4‐ethylenedioxythiophene and aniline monomers. Stationary electropolymerization produces individual microspots; lateral movement produces long microribbons; retraction produces extruded microstructures. Subsequently the same SPM setup is tipped with a double‐barreled micropipette to carry out localized cyclic voltammetry. The micropipettes are filled with saline solutions in contact with Ag/AgCl electrodes, forming a thin meniscus of solution at the micropipette tip, which enable an automated approach in air and subsequent contact with the surface. The flexibility of this novel technique is demonstrated by application to 2D poly(3,4‐ethylenedioxythiophene) (PEDOT) microspots, microribbons and nanowires, plus polyaniline (PANI) microstructures and self‐assembled thin films. Finally, setting up a dynamic electrochemical cell allowed for voltammetric–amperometric imaging, simultaneously mapping the morphology and current response of CPs. Future refinements towards the nanoscale through smaller‐tipped pipettes should open up new opportunities for voltammetric response mapping of individual CP nanostructures.