Effects of Thermal‐Diffusion,Diffusion‐Thermo,and Space Porosity on MHD Mixed Convective Flow of Micropolar Fluid in a Vertical Channel with Viscous Dissipation

This paper examines thermal‐diffusion and diffusion‐thermo effects on the fully developed MHD flow of a micropolar fluid through a porous space in a vertical channel with asymmetric wall temperatures and concentrations. The homotopy analysis method (HAM) is adopted to obtain the approximate analytical solution for the velocity, micro‐rotation, temperature, and concentration field. The convergence and the accuracy of the solutions are discussed. The role of pertinent parameters on the heat and mass transfer characteristics of the flow are presented graphically. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(6): 561–576, 2014; Published online 11 November 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21100     

BST Varactor Loaded Frequency Agile Stacked Circular Microstrip Radiator

A new frequency agile BST varactor loaded stacked circular microstrip antenna is presented. The antenna is analysed using extended cavity model. One of two bands of antenna is tunable with the help of BST varactor. The upper band is useful for WiMAX and lower band for other wireless communication systems. Various antenna parameters like return loss, resonant frequency, frequency agility etc. have been investigated. The simulated results agree well with the numerical data. A frequency agility of 60.64 % is achieved, which is better than simple Varactor diode loaded antenna. Lowest resonant frequency of 0.866 GHz is obtainable that shows a significant physical area reduction. The group delay of S $_{11}$ remains constant for entire band of operation.     

Ultra-Wideband L-Strip Proximity Coupled Slot Loaded Circular Microstrip Antenna for Modern Communication Systems

An analysis and design of a novel ultra wideband L-strip proximity coupled slot loaded circular microstrip antenna is proposed. The theoretical model is developed using circuit theoretic approach and obtained results are validated by MoM based IE3D simulation software. Theoretical results show a good agreement with simulated results. The patch is designed on a thick substrate of thickness 11 mm for a design frequency of 3.74 GHz and provides ultra wide band operation. The parametric study is carried out for return loss, radiation pattern, antenna efficiency, radiation efficiency and gain. It is observed that the bandwidth of the antenna depends on slot parameter and L-strip feed dimensions. An ultra bandwidth of 2.82 GHz is achieved with consistent radiation characteristics.     

Development of poly(dimethylsiloxane)–titania nanocomposites with controlled dielectric properties: Effect of heat treatment of titania on electrical properties

Polymer–ceramic composites were prepared using poly(dimethylsiloxane) as base matrix and normal as well as heat‐treated titania as fillers. Dielectric and mechanical properties of the composites were measured and found that dielectric constant of the composites was increased dramatically with the addition of filler, whereas resistivity was decreased. Hardness and modulus were found to increase but tensile strength, % elongation at break, and tear strength were decreased with the filler loading. Neat titania contains some moisture (physisorbed and chemisorbed) as revealed from thermogravimetric analysis. Both electrical and mechanical properties of the composites were affected by filler heat treatment. Further, untreated titania contains Ti³⁺ and Ti⁴⁺, which on heat treatment, increases the concentration of Ti⁴⁺, as a result electrical properties were affected. Filler dispersion in the composites was studied by field emission scanning electron microscopy and high resolution transmission electron microscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of SBS Content on Low Temperature Impact Strength,Morphology and Rheology of PP-cp/SBS Blends

Izod impact strength of PP impact copolymer/Styrene-Butadiene-Styrene blends were evaluated at varied sub-zero temperatures and demonstrated 12 times enhancement in impact strength of 40% SBS containing blend over pure PP-cp at ?40°C. SBS content played a vital role in morphology development as it changes from droplet morphology to elongated ellipsoid to a seemingly networked structure leading towards different fracture mechanisms. Rheological properties of blends evaluated on capillary rheometer showed pseudoplastic behavior at varied shear rates (50 ? 10⁴ s^?1) at 220°C and good agreement between experimental shear viscosity and theoretical values as per log additivity principle at high shear rates.     

NSMTSEP: Neighbor Supported Modified Threshold Sensitive Stable Election Protocol for WSN

The way by which we select a cluster head critically affects the overall futuristic structure in the network. Cluster head wastes more energy for long distance transmission in the network. Sometimes, due to incomplete information of neighbor nodes, a proper cluster head is not selected and deplete energy quickly. This paper, presents a clustering protocol (NSMTSEP) based on neighbor support. Support of the neighbor node is used to calculate the threshold. Neighbor nodes are labeled based on dynamically changing parameters. The total energetic value of different nodes, cluster heads degree, the summative information of distances of member nodes, etc. is dynamically changing parameters. The label of a node is used to calculate the weight of that particular node. Weight is finally used to formulate equations for threshold calculation. The fundamental target is to increase the stable time, throughput, and network lifespan by reducing the cost incurred in intra-cluster communication. Neighbor supported labeled method is suitable for increasing longevity in the network. NSMTSEP upgrades stability by 8.6%, 36.9% as compared to enhanced threshold sensitive stable election protocol (ETSSEP) and threshold sensitive stable election protocol (TSEP). NSMTSEP is three times more stable than stable election protocol (SEP) and low energy adaptive clustering hierarchy protocol (LEACH). Improvement in the lifespan of NSMTSEP is recorded by 11.98%, 3.43% and 24.9% over ETSSEP, TSEP, and LEACH respectively whereas more than twice in comparison with SEP. The throughput enhanced by 32.2% and 55.7% respectively over TSEP and LEACH, twice over SEP and ETSSEP respectively.

     

A robust salient object detection using edge enhanced global topographical saliency

Multimedia Tools and Applications - Complex salient object detection is the most challenging task in clutter background images. In this prevailing problem, global contrast-based methods are...     

Unsteady squeezing flow of magnetic hybrid nanofluids within parallel plates and entropy generation

Nowadays, due to the novel thermal effectiveness, a new class of fluid, named “hybrid nanofluid,” is used. It has significant applications in domestic and industrial fields. In this study, we investigated the entropy generation and heat transfer of unsteady squeezing magnetic hybrid nanofluid flow between parallel plates by considering heat source/sink and thermal radiation. In this analysis, carbon nanotubes (CNTs) (single‐walled carbon nanotube and multiwalled carbon nanotube) are considered as nanoparticles that are dispersed in water‐ethylene glycol (EG) mixtures (ie, 70%W + 30%EG and 50%W + 50%EG). For the analysis of the physical behavior of hybrid nanofluids, new models related to hybrid nanofluids are incorporated. From this study, it has been observed that as the hybrid nanofluids moved away from the surface, the entropy generation outlines accelerated with an increase in magnetic field values. Moreover, an increase in the volume fraction of CNTs, the thermal conductivity of 50%W + 50%EG + CNTs hybrid nanofluid is greater than 70%W + 30%EG + CNTs hybrid nanofluid.     

The role of rheological premonitory of hydrogels based on cellulose nanofibers and polymethylsilsesquioxane on the physical properties of corresponding aerogels

Cellulose nanofibers (CNFs) and polymethylsilsesquioxane (PMSQ)-based aerogels (CNF/PMSQ aerogels) have been prepared by the sol–gel method. The extraction of CNFs from pine wood and formation of composite aerogel with PMSQ were confirmed by Fourier transform infrared spectroscopic and field emission scanning electron microscopic analyses. The rheological premonitory of hydrogel has been performed to predict the physical properties (i.e., density, mechanical properties) of aerogels. The variation in the precursor (methyltrimethoxysilane [MTMS]) and urea content has shown a considerable effect on the storage modulus and phase angle of the hydrogel. The variation in urea content showed a 4–8% increment in the density with a pronounced difference in aerogel's morphology. The increment in the MTMS concentration demonstrated a 10–20% enhancement in density with a minor change in morphology. The van Gurp–Palmen plot of hydrogel has represented a relationship between complex modulus and phase angle. This study establishes that hydrogel's premonitory analysis could compare aerogel's physical properties without going through drying and further analysis.