An adaptive reservation scheme for optical network

In this paper, the various Optical Burst Switching (OBS) reservation schemes have been examined in order to reduce data loss caused by either channel scheduling or resources. A novel multi-service OBS edge node with synchronized bandwidth reservation mechanism (SRM) has been proposed, which enables high-speed network transport nodes to dynamically reserve bandwidth needed for active data burst flows. The performance of the proposed mechanism is evaluated by means of NS-2 simulation. The results show that the packet delay is kept within the constraint for each traffic flow and the performance metrics such as burst loss rate, throughput and fairness are remarkably improved.     

Formation of Gallium-induced nanostructures on single crystal HOPG surface

The room temperature growth of gallium atoms on the highly oriented pyrolytic graphite (HOPG) surface has been performed. The gallium atoms were deposited by thermal evaporation method in an ultra high vacuum system at a base pressure 5 × 10⁻¹⁰ torr. The X-ray photo electron spectroscopy (XPS) studies had been performed to confirm the presence of gallium atoms on HOPG surface. Scanning tunneling spectroscopy (STM) technique was employed to study the surface morphology of the clean HOPG surface and gallium covered HOPG surfaces which recognize the formation of gallium induced nanostructures. The deconvoluted XPS core level spectra of C (1s) and Ga (3d) demonstrate the possible interaction between substrate and the adsorbate atoms. The STM analysis revealed that the gallium deposition on HOPG led to significant change in the surface morphology. It was observed that the Ga atoms adsorbed as layer structure on HOPG surface for low coverage while quasi one-dimensional chain like nanostructure (1 ± 0.2 nm) has been formed for higher Ga coverage. The nanostructured surfaces induced by Ga deposition are found to be stable and could be used as a template for the growth of metallic nanostructures.     

Diffusion of water in molecular magnet Cu(0.75)Mn(0.75)[Fe(CN)6]·7H2O

Here we report the dynamical behaviour of water in Prussian blue analogue (PBA) Cu(0.75)Mn(0.75)[Fe(CN)(6)]·7H(2)O molecular magnet in the temperature range 260-360 K as studied using the quasielastic neutron scattering technique. While significant quasielastic broadening is observed in the hydrated sample, no broadening was observed in the dehydrated one. Data analysis showed that the observed quasielastic broadening in Cu(0.75)Mn(0.75)[Fe(CN)(6)]·7H(2)O corresponds to the dynamics of the non-coordinated water molecules at the 32f site and the coordinated water molecules at the 24e site, existing in the cavities created by the absence of Fe(CN)(6) units. The non-coordinated water molecules at 8c interstitial sites do not contribute to the broadening, suggesting that they are immobile at least within the time window of the spectrometer used. Behaviour of the elastic incoherent structure factor is consistent with the model where the water molecules undergo translational diffusion localized within the cavity of 5.1 ?. While all the non-coordinated water molecules at the 32f site are dynamic over the entire range of temperatures, the coordinated ones at the 24e site become progressively dynamic with temperature. The water molecules were found to undergo hindered (~1.16 × 10(-5) cm(2) s(-1) at 300 K) diffusion compared to bulk water and the diffusivity followed Arrhenius behaviour within the measured temperature range with an activation energy of 1.26 kcal mol(-1).     

Dielectric shielded nanoscale patch laser resonators

Dielectric shielded nanoscale patch laser resonators are introduced. Low-index dielectric shield layers surrounding a high-index core are shown to significantly reduce both metal and radiation losses. Structures suitable for both optical and electrical pumping and smaller than the vacuum wavelength in all three dimensions are shown to have a low enough threshold gain to lase at room temperature. Shifting the gain medium core provides control over the radiation pattern of the resonator and enables coupling of the laser light into a waveguide, opening opportunities for chipscale integration.     

Optical and hydrophobic properties of co-sputtered chromium and titanium oxynitride films

The chromium and titanium oxynitride films on glass substrate were deposited by using reactive RF magnetron sputtering in the present work. The structural and optical properties of the chromium and titanium oxynitride films as a function of power variations are investigated. The chromium oxynitride films are crystalline even at low power of Cr target (≥60 W) but the titanium oxynitride films are amorphous at low target power of Ti target (≤90 W) as observed from glancing incidence X-ray diffraction (GIXRD) patterns. The residual stress and strain of the chromium oxynitride films are calculated by sin² ψ method, as the average crystallite size decreases with the increase in sputtering power of the Cr target, higher stress and strain values are observed. The chromium oxynitride films changes from hydrophilic to hydrophobic with the increase of contact angle value from 86.4° to 94.1°, but the deposited titanium oxynitride films are hydrophilic as observed from contact angle measurements. The changes in surface energy were calculated using contact angle measurements to substantiate the hydrophobic properties of the films. UV-vis and NIR spectrophotometer were used to obtain the transmission and absorption spectra, and the later was used for determining band gap values of the films, respectively. The refractive index of chromium and titanium oxynitride films increases with film packing density due to formation of crystalline chromium and titanium oxynitride films with the gradual rise in deposition rate as a result of increase in target powers.     

On some new m-spotty Lee weight enumerators

One of the objectives of coding theory is to ensure reliability of the computer memory systems that use high-density RAM chips with wide I/O data (e.g. 16, 32, 64 bits). Since these chips are highly vulnerable to m-spotty byte errors, this goal can be achieved using m-spotty byte error-control codes. This paper introduces the m-spotty Lee weight enumerator, the split m-spotty Lee weight enumerator and the joint m-spotty Lee weight enumerator for byte error-control codes over the ring of integers modulo ? (? ≥  2 is an integer) and over arbitrary finite fields, and also discusses some of their applications. In addition, MacWilliams type identities are also derived for these enumerators.     

Determination of selenomethionine by high performance liquid chromatography-direct hydride generation-atomic absorption spectrometry

A simple, reliable, trace determination of selenomethionine (Semet) based on a direct hydride generation atomic absorption spectrometric method was developed using sodium tetrahydroborate (0.3% in 0.2% NaOH) and hydrochloric acid (3 M). The method excluded any chemical pretreatment prior to hydride generation (HG). The optimized HG system was successfully coupled with the HPLC system. The detection limit (3σ of blank; n=5), reproducibility (R.S.D. of three successive analyses/day, performed on three different days), and repeatability (R.S.D. of three successive analyses) of the method were 1.08 ng ml⁻¹, 9.8% for 9.04 ng ml⁻¹ and 2.1–9.5% for 30.0–1.27 ng ml⁻¹ Semet as Se (standards prepared in Milli-Q water). Calibration graph was linear up to 30 ng ml⁻¹. This HPLC-HG-AAS method is very promising and successfully determined Semet (spiked) in human urine.     

A hybrid FVM–LBM method for single and multi‐fluid compressible flow problems

The lattice Boltzmann method (LBM) has established itself as an alternative approach to solve the fluid flow equations. In this work we combine LBM with the conventional finite volume method (FVM), and propose a non‐iterative hybrid method for the simulation of compressible flows. LBM is used to calculate the inter‐cell face fluxes and FVM is used to calculate the node parameters. The hybrid method is benchmarked for several one‐dimensional and two‐dimensional test cases. The results obtained by the hybrid method show a steeper and more accurate shock profile as compared with the results obtained by the widely used Godunov scheme or by a representative flux vector splitting scheme. Additional features of the proposed scheme are that it can be implemented on a non‐uniform grid, study of multi‐fluid problems is possible, and it is easily extendable to multi‐dimensions. These features have been demonstrated in this work. The proposed method is therefore robust and can possibly be applied to a variety of compressible flow situations. Copyright © 2009 John Wiley & Sons, Ltd.     

An eco-safe approach to benzopyranopyrimidines and 4H-chromenes in ionic liquid at room temperature

An environmentally benign, ionic liquid promoted multicomponent protocol to benzopyrano(2,3-d)pyrimidines and 4H-chromenes has been developed at room temperature. Results of the reaction depend on the nature of the nucleophile used in the reaction. Secondary amines result in the formation of benzopyrano(2,3-d)pyrimidines, whereas thiols give rise to 4H-chromenes under the same set of reaction conditions.