Superimposed long period fiber grating-based refractive index sensor

A superimposed long period fiber grating design proposed for refractive index sensing is shown to be superior to conventional dual resonance and turnaround point gratings and can operate at any chosen wavelength region by appropriate design. Numerical simulations carried out on standard single mode fibers show that such sensors can operate over a wide refractive index range (1.33–1.42) exhibiting a high sensitivity of ～500–1545?nm/RIU, yielding ～10^?6–10^?7 refractive index change corresponding to the resonance relative shift of 1?pm with potential applications to chemical and biological industries. The proposed scheme can also discriminate between refractive index and temperature changes.     

Broadband parametric amplification in Bragg reflection waveguide

A novel scheme for enhancing the bandwidth of optical parametric amplification using asymmetric Bragg reflection waveguides is presented. The unique dispersion characteristics exhibited by the Bragg reflection waveguides are exploited for countering the rapidly falling signal gain as one moves away from the phase-matching wavelength. The role of the periodic cladding on the gain and bandwidth of optical parametric amplification in a lithium niobate based Bragg reflection waveguide is analysed. Such an idea could be used in any nonlinear up conversion or down conversion process for enhancing the bandwidth significantly and for easing fabrication tolerances.     

Polarization characteristics of elliptic-core fibers with stress induced anisotropy

We present a simple analytical method to study birefringence and polarization mode dispersion (PMD) of elliptic-core fibers with uniform or differential stress in the fiber cross section. The model takes account of both geometrical and stress birefringence, simultaneously. It is found that neglecting the geometrical birefringence, even under the weakly guiding approximation, can lead to significant errors in the calculation of PMD and the zero PMD wavelength. It is also found that one can obtain zero PMD in the single-mode region even by applying a suitable differential stress along the major axis. This is very attractive since then the geometrical and stress birefringences add up to give increased total birefringence.     

A Unified Architecture for the Design and Evaluation of Wireless Fair Queueing Algorithms

Fair queueing in the wireless domain poses significant challenges due to unique issues in the wireless channel such as location-dependent and bursty channel errors. In this paper, we present a wireless fair service model that captures the scheduling requirements of wireless scheduling algorithms, and present a unified wireless fair queueing architecture in which scheduling algorithms can be designed to achieve wireless fair service. We map seven recently proposed wireless fair scheduling algorithms to the unified architecture, and compare their properties through simulation and analysis. We conclude that some of these algorithms achieve the properties of wireless fair service including short-term and long-term fairness, short-term and long-term throughput bounds, and tight delay bounds for channel access.     

MULTI-OBJECTIVE RECONFIGURABLE OUTPUT FEEDBACK CONTROLLER FOR MIMO SYSTEM USING MOEAS

This article deals with the design of a parametric eigenstructure assignment (PEA)-based multi-objective reconfigurable output feedback controller for a multiple-input multiple-output (MIMO) system against partial actuator failure. The significance of the PEA technique is that it provides more design degrees of freedom to obtain multi-objective functions, namely robust stability and improved transient response. Robust stability and transient response are ensured by a minimum condition number of the eigenvector and a minimum norm of controller gain. These two objectives are conflicting in nature, and, hence, the main aim is to minimize both objectives simultaneously by means of a multi-objective evolutionary algorithm (MOEA). In this study, a multi-objective optimization problem is formulated and is solved by non-dominated sorting genetic algorithm-II (NSGA-II) and strength Pareto evolutionary algorithm-II (SPEA-II). Four indicators are used to evaluate each algorithm performance: spacing, error ratio, generational distance, and hypervolume. Then a reconfigurable controller is designed using PEA against actuator failure, which guarantees closed-loop stability. The effectiveness of the proposed controllers is demonstrated by implementing them in an interacting three-tank benchmark system.     

Rapid-onset dystonia-parkinsonism in a second family

Rapid-onset dystonia-parkinsonism (RDP), first described in a large Midwestern family, is now reported in a second, apparently unrelated, family in which four individuals have this same syndrome. All four developed sudden onset of dysarthria, dysphagia, severe dystonic spasms, bradykinesia, and postural instability over less than 1 hour to a few days. Three of the four had stable limb dystonia for several years preceding the onset of combined dystonia-parkinsonism. Treatment with levodopa/carbidopa provided little benefit. We propose diagnostic criteria for RDP and further define the spectrum of this unusual disease.     

Analysis and design of a novel leaky YIG film guided wave opticalisolator

A guided wave optical isolator using a four layered leaky yttrium iron garnet (YIG) waveguide with a YIG guiding layer is proposed and analyzed through a transfer matrix formulation. The dependence of isolation characteristics on different waveguide parameters are discussed. It is shown that for four layered structures an isolation ratio of about 24 dB can be achieved with YIG films having large gyrotropy. It is also shown that by replacing the single guiding YIG film with multilayers of YIG with compensated walls and proper permittivity, high isolation ratio can be achieved even with currently available YIG films having low gyrotropy     

Effect of argon dilution on the pre-ignition oxidation kinetics of benzene

Experimental and modelling studies on the high-temperature oxidation of benzene have been done to study the effect of argon dilution on its pre-ignition thermochemical kinetics. The ignition delay times of stoichiometric C₆H₆/O₂ mixtures are measured behind reflected shock waves at a total pressure of 4 bar with varying argon dilution (0–95%) for a wide range of temperatures (650–2200 K). A kinetic scheme with 60 elementary reactions among 23 reacting species is proposed which is able to predict the experimental results obtained in this as well as earlier studies. The model was subjected to a sensitivity analysis to identify the significant reactions. The effects of diluent concentration on the reaction rates and energy release history in the vicinity of the induction times are reported. Correlations are deduced to predict the ignition delay times. The thermal and kinetic effects of argon concentration on the ignition activation energy and induction times are examined.     

A parallel elliptic curve crypto-processor architecture with reduced clock cycle for FPGA platforms

The Journal of Supercomputing - The Elliptic curve cryptosystem is a public-key cryptosystem that receives more focus in recent years due to its higher security with smaller key size when compared...     

Spectral Measurement of the Film-Substrate Index Difference in Proton-Exchanged LiNbO(3) Waveguides

We report the spectral characterization of proton-exchanged lithium niobate (PE:LiNbO(3)) waveguides in terms of the variation of the refractive-index difference between the waveguiding layer and the substrate. The dispersion of the extraordinary refractive-index increase (deltan(e)) is measured from 405 to 1319 nm with several light sources. Two types of proton-exchanged waveguide, prepared under different conditions, are studied. These measurements should be of use in the optimization of PE:LiNbO(3) waveguides for nonlinear optical applications, particularly in second-harmonic generation in the blue-green wavelength region.