A hybrid evolutionary approach to the registration area planning problem

The last two decades have witnessed a phenomenal growth in the number of cellular wireless network users which in turn stressed the need to utilize the limited network bandwidth in an efficient manner. The network bandwidth is consumed not only by user traffic, but also by control traffic needed for ensuring the mobility of users. As we don’t have any control over the volume of user traffic, all attempts to efficiently use bandwidth are based on frequency reuse and minimizing the control traffic. The registration area planning (RAP) problem seeks a partition of the cells of the network into contiguous areas called registration areas so that the bandwidth consumed by control signals is minimized. RAP problem in an \(\mathcal {NP}\) -Hard problem. In this paper, we present a steady-state grouping genetic algorithm with local search to solve this problem. We have compared our approach with the state-of-the-art approaches reported in the literature. Computational results show the effectiveness of our approach.     

Interpolation of images using discrete wavelet transform to simulate image resizing as in human vision

This paper presents discrete wavelet transform (DWT) and its inverse (IDWT) with Haar wavelets as tools to compute the variable size interpolated versions of an image at optimum computational load. As a human observer moves closer to or farther from a scene, the retinal image of the scene zooms in or out, respectively. This zooming in or out can be modeled using variable scale interpolation. The paper proposes a novel way of applying DWT and IDWT in a piecewise manner by non-uniform down- or up-sampling of the images to achieve partially sampled versions of the images. The partially sampled versions are then aggregated to achieve the final variable scale interpolated images. The non-uniform down- or up-sampling here is a function of the required scale of interpolation. Appropriate zero padding is used to make the images suitable for the required non-uniform sampling and the subsequent interpolation to the required scale. The concept of zeroeth level DWT is introduced here, which works as the basis for interpolating the images to achieve bigger size than the original one. The main emphasis here is on the computation of variable size images at less computational load, without compromise of quality of images. The interpolated images to different sizes and the reconstructed images are benchmarked using the statistical parameters and visual comparison. It has been found that the proposed approach performs better as compared to bilinear and bicubic interpolation techniques.     

Graphene oxide reinforced polyvinyl alcohol/polyethylene glycol blend composites as high-performance dielectric material

Novel flexible dielectric composites composed of polyvinyl alcohol (PVA), polyethylene glycol (PEG), and graphene oxide (GO) with high dielectric constant and low dielectric loss have been developed using facile and eco-friendly colloidal processing technique. The structure and morphology of the PVA/PEG/GO composites were evaluated using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The dielectric behavior of PVA/PEG/GO composites was investigated in the wide range of frequencies from 50 Hz to 20 MHz and temperature in the range 40 to 150 °C using impedance spectroscopy. The dielectric constant for PVA and PVA/PEG (50/50) blend film was found to be 10.71 (50 Hz, 150 °C) and 31.22 (50 Hz, 150 °C), respectively. The dielectric constant for PVA/PEG/GO composite with 3 wt% GO was found to be 644.39 (50 Hz, 150 °C) which is 60 times greater than the dielectric constant of PVA and 20 times greater than the dielectric constant of PVA/PEG (50/50) blend film. The PVA/PEG/GO composites not only show high dielectric constant but also show low dielectric loss which is highly attractive for practical applications. These findings underline the possibilities of using PVA/PEG/GO composites as a flexible dielectric material for high-performance energy storage applications such as embedded capacitors.     

Dynamic mechanical analysis and broadband electromagnetic interference shielding characteristics of poly (vinyl alcohol)-poly (4-styrenesulfonic acid)-titanium dioxide nanoparticles based tertiary nanocomposites

ABSTRACT

Novel tertiary nanocomposite films comprising of poly (vinyl alcohol) (PVA), poly (4-styrenesulfonic acid) (PSSA) and titanium dioxide (TiO₂) nanoparticles (NP_S) were prepared using simple solvent casting method. The structural, thermal, morphological, thermo-mechanical and electromagnetic interference (EMI) shielding properties of PVA/PSSA/TiO₂ nanocomposite films were investigated. The EMI shielding effectiveness (SE) of PVA/PSSA/TiO₂ nanocomposite films in the X and Ku band was found to be 12 dB and 13 dB respectively at 25 wt% TiO₂ NPs loading. These results demonstrate the possible applications of PVA/PSSA/TiO₂ nanocomposite films as low cost, lightweight and flexible material for EMI shielding.     

Climate Change Impact Assessment on Blue and Green Water by Coupling of Representative CMIP5 Climate Models with Physical Based Hydrological Model

Water Resources Management - Climatic changes have altered hydrological and climatic parameters worldwide, and climate projections suggest that such alterations will continue. In order to maintain...     

Effects of veratridine on the action potentials and contractility of right and left ventricles from normo- and hypertensive rats

Induction of nitric oxide synthase and generation of nitric oxide in pancreatic islet beta-cells may mediate cytokine-induced dysfunction leading to insulin-dependent diabetes mellitus. Nitric oxide generation can be regulated by availability of arginine substrate which, in turn, may be affected by substrate utilization in competing pathways such as the arginase-catalysed formation of ornithine and urea. In this study we have investigated the activity of arginase in the rat insulinoma-derived cell line RINm5F and the effect on this of interleukin 1beta, the nitric oxide synthase reaction intermediate NG-hydroxy-l-arginine and the nitric oxide-generating compounds 3-morpholinosydnonimine and S-nitrosoglutathione. Cytosols from RINm5F cells treated with or without interleukin 1beta (0.1nM, 18h) were incubated (45min, 37 degrees C) with [U-14C]arginine. Radiolabelled products ([14C]citrulline from nitric oxide synthase, [14C]ornithine and [14C]urea from arginase) were separated by high-performance liquid chromatography or ion-exchange chromatography. Interleukin 1beta increased citrulline production (from 0.01+/-0.002 to 0.58+/-0.03 pmol/microg cell protein), indicating induction of nitric oxide synthase, and significantly decreased production of both ornithine (from 4.60+/-0.20 to 3.40+/-0.20 pmol/microg) and urea (0.93+/-0.05 to 0.69+/-0.04 pmol/microg) (P<0.001), indicating decreased activity of arginase. Arginase was significantly inhibited by NG-hydroxy-l-arginine (IC50=50 microM), S-nitrosoglutathione (500 microM: 69+/-7% of control) and 3-morpholinosydnonimine (1 mM: 57+/-7% of control) (P<0.05). We conclude that during cytokine-directed beta-cell assault nitric oxide synthase-catalysed production of NG-hydroxy-l-arginine and nitric oxide may inhibit arginase thereby increasing the availability of arginine for nitric oxide production.     

Solid‐state NMR study of spin finish of thermally treated PAN and PAN/CNT precursor fibers

Dry‐jet wet‐spun polyacrylonitrile (PAN) and PAN/carbon nanotubes (CNTs) precursor fibers coated by spin finishes were characterized using the solid‐state ¹H nuclear magnetic resonance technique. Series of fiber samples were prepared upon thermal treatment at different temperatures (room temperature to 180°C). Using the Hahn echo sequence, relatively mobile components were identified and the effect of the heat treatment on those components was studied. It was observed that the mobile components are mainly the spin finishes. Heat treatment caused loss of one of the spin finishes (Type B) to a great extent (～80%), whereas the other two spin finishes (Type A and Type C) were more stable. Additional information regarding the change in molecular mobility due to heat treatment was obtained by the spin‐lattice relaxation time ( T₁ ) analysis. It was found that the presence of CNT affects the T₁ relaxation time of the polymer in the composite fiber, however, that of relatively mobile components remains unaffected. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40734.     

Atomic Friction Investigations on Ordered Superstructures

We review recent friction measurements on ordered superstructures performed by atomic force microscopy. In particular, we consider ultrathin KBr films on NaCl(001) and Cu(001) surfaces, single and bilayer graphene on SiC(0001), and the herringbone reconstruction of Au(111). Atomically resolved friction images of these systems show periodic features spanning across several unit cells. Although the physical mechanisms responsible for the formation of these superstructures are quite different, the experimental results can be interpreted within the same phenomenological framework. A comparison between experiments and modeling shows that, in the cases of KBr films on NaCl(001) and of graphene films, the tip-surface interaction is well described by a potential with the periodicity of the substrate which is modulated or, respectively, superimposed with a potential with the symmetry of the superstructure.