Enhancement of Flux Pinning in YBa2Cu3O7−δ + Ag Nanocomposites

YBa₂Cu₃O_7?δ /Ag thin film is prepared through pulsed laser deposition. The presence of Ag brings about significant inter- and intragranular modification in the microstructure of the composites. The resistive broadening in the tail part is suggested to be associated with the link between the grains and to be extremely sensitive to magnetic fields. It is assumed that the zero resistance state at the T _c0 region of the above high temperature superconductor is governed by the excitations in the weak link network. Invoking Beans critical state model, enhancement in critical current density J _c is observed.     

Improved direct torque control of induction motor with dither injection

In this paper, a three-level inverter-fed induction motor drive operating under Direct Torque Control (DTC) is presented. A triangular wave is used as dither signal of minute amplitude (for torque hysteresis band and flux hysteresis band respectively) in the error block. This method minimizes flux and torque ripple in a three-level inverter fed induction motor drive while the dynamic performance is not affected. The optimal value of dither frequency and magnitude is found out under free running condition. The proposed technique reduces torque ripple by 60% (peak to peak) compared to the case without dither injection, results in low acoustic noise and increases the switching frequency of the inverter. A laboratory prototype of the drive system has been developed and the simulation and experimental results are reported.     

Aspects of signal-dependent noise characterization

An automated method is presented for analyzing signal-dependent noise. Signal-dependent noise is present in many types of data-acquisition processes and has been investigated by other researchers with various methods. Regardless of the noise analysis methods, often the starting point is based on a particular signal-dependent noise model, which also forms the basis for our study. The approach determines whether the estimated noise variance is dependent on the signal by approximating the functional relation within the constraints of the assumed signal-noise model. The method relies on the Fourier attributes of the signal and noise and uses the wavelet expansion for separating these components. The technique does not rely on the underlying noise and signal probability distributions. Two-dimensional simulations as well as mammography data are used to illustrate the merits of the approach.     

Lanolin‐based organogels as a matrix for topical drug delivery

The current study deals with the development of lanolin‐based emulsion gels by hot emulsification method. Bright‐field, phase contrast, and fluorescent micrographs of the gels have shown the uniform distribution of circular water droplets in the formulations. Coalescence of water droplets was observed in gels containing higher proportion of water. Fourier transform infrared spectrophotometric studies indicated absence of Ln‐drug chemical interactions. X‐ray diffraction studies suggested an increase in amorphousness of the gels with the incorporation of water into the gel structure. The salicylic acid (SA), model drug, release from the gels was found to follow Higuchi kinetics. Krossmeyer–Peppas model fitting indicated non‐Fickian release of the drug. As the water content of the gels increased, there was a corresponding increase in the rate of release of the drug. The gels showed non‐Newtonian and thixotropic flow behavior. The gel to sol transition and melting temperatures of the gels were identified by differential scanning calorimetric (DSC) thermal analysis and falling ball method. DSC thermograms indicated an increase in thermal stability with the increase of water content in the gels. The gels showed sufficient spreadability and biocompatibility characteristics to be used as topical formulations. SA loaded gels showed good antimicrobial efficacy against Bacillus subtilis, a Gram‐positive bacterium. Based on the preliminary studies, the developed gels may be regarded as carriers in topical drug delivery. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Controlling of Floating-Body and Thermal Conductivity in Short Channel SOI MOSFET at 30 nm Channel Node

Silicon - Ultra low-power Silicon-on-Insulator (SOI) transistor makes it possible to lower the supply voltage and reduce the power dissipation. However, these SOI MOSFET are still suffering from...     

Study of combined effect of natural convection and radiation heat transfer from annular finned vertical cylinder

The present numerical study reports the combined effect of natural convection and radiation heat from a vertical cylinder with annular fins. The study involves simulation for laminar as well as turbulent regimes. For the present study, Rayleigh's number is varied in the range ${10}^8-{10}^{12}$, emissivity in the range $0.2-0.8$, and the fin spacing ratio (s/d) in the range $0.1-10$. The radiation heat transfer has been found to share a considerable amount in the total heat transfer of the system for the laminar regime, but in the turbulent regime, its effect is minimal and can be neglected. When the fin spacing ratio is reduced, the total heat transfer increases for both the turbulent and laminar flow conditions. But the radiation heat increases with a reduction in fin spacing ratio for laminar and in case of turbulent flow radiation heat rate reduces with a reduction in s/d ratio. For the range of Rayleigh numbers considered in the present study, the Nusselt number increases with the increment of the fin spacing ratio. Thus, it can be concluded that there is a remarkable enhancement in the heat transfer rate in laminar cases with the fins. For turbulent cases, the fin efficiency lies between 40% and 50%.