Kuru Ratnavelu

Robust stability analysis for discrete-time uncertain neural networks with leakage time-varying delay

Abstract This paper is concerned with the stability problem for a class of discrete-time neural networks with time-varying delays in network coupling, parameter uncertainties and time-delay in the leakage term. By constructing triple Lyapunov–Krasovskii functional terms, based on Lyapunov method, new sufficient conditions are established to ensure the asymptotic stability of discrete-time delayed neural networks system. Convex reciprocal technique is incorporated to deal with double summation terms and the stability criteria are presented in terms of linear matrix inequalities (LMIs). Finally numerical examples are exploited to substantiate the theoretical results. It has also shown that the derived conditions are less conservative than the existing results in the literature.

Synchronization and an application of a novel fractional order King Cobra chaotic system.

In this paper, we design a new three dimensional King Cobra face shaped fractional order chaotic system. The multi-scale synchronization scheme of two fractional order chaotic systems is described. The necessary conditions for the multi-scale synchronization of two identical fractional order King Cobra chaotic systems are derived through feedback control. A new cryptosystem is proposed for an image encryption and decryption by using synchronized fractional order King Cobra chaotic systems with the supports of multiple cryptographic assumptions. The security of the proposed cryptosystem is analyzed by the well known algebraic attacks. Numerical simulations are given to show the effectiveness of the proposed theoretical results.

Excitation of electronic states in tetrahydrofuran by electron impact

We report on differential and integral cross section measurements for the electron impact excitation of the three lowest lying Rydberg bands of electronic states in tetrahydrofuran. The energy range of the present experiments was 15-50 eV with the angular range of the differential cross section measurements being 15°-90°. The important effects of the long-range target dipole moment and the target dipole polarizability, on the scattering dynamics of this system, are evident from the present results. To the best of our knowledge, there are no other theoretical or experimental data against which we can compare the cross section results from this study.

Positron scattering from hydrogen atom embedded in dense quantum plasma

Scattering of positrons from the ground state of hydrogen atoms embedded in dense quantum plasma has been investigated by applying a formulation of the three-body collision problem in the form of coupled multi-channel two-body Lippmann-Schwinger equations. The interactions among the charged particles in dense quantum plasma have been represented by exponential cosine-screened Coulomb potentials. Variationally determined hydrogenic wave function has been employed to calculate the partial-wave scattering amplitude. Plasma screening effects on various possible mode of fragmentation of the system e++H(1s) during the collision, such as 1s→1s and 2s→2s elastic collisions, 1s→2s excitation, positronium formation, elastic proton-positronium collisions, have been reported in the energy range 13.6-350 eV. Furthermore, a comparison has been made on the plasma screening effect of a dense quantum plasma with that of a weakly coupled plasma for which the plasma screening effect has been represented by the Debye model. ...

Positron scattering from argon: total cross sections and the scattering length

We report results from new positron–argon total cross-section (TCS) measurements. Agreement with the corresponding recent data of Jones et al (2011 Phys. Rev. A 83 032701) is found to be very good, except at the lowest energies of common measurement. Excellent qualitative agreement is also found between our measurements and an improved convergent close-coupling (CCC) calculation which was undertaken as a part of this study. This level of accord between our experimental and theoretical TCSs has enabled us to determine an experimental scattering length (a) of a = −4.9 ± 0.7 au for the positron–argon system. That value is in excellent agreement with the relativistic polarized orbital optical potential approach result of Jones et al (a = −4.7 au) and our CCC result of a = −4.3 au.

Differential cross sections for electron impact excitation of the electronic bands of phenol

We report results from a joint theoretical and experimental investigation into electron scattering from the important organic species phenol (C6H5OH). Specifically, differential cross sections (DCSs) have been measured and calculated for the electron-impact excitation of the electronic states of C6H5OH. The measurements were carried out at energies in the range 15-40 eV, and for scattered-electron angles between 10° and 90°. The energy resolution of those experiments was typically ∼80 meV. Corresponding Schwinger multichannel method with pseudo-potentials calculations, with and without Born-closure, were also performed for a sub-set of the excited electronic-states that were accessed in the measurements. Those calculations were conducted at the static exchange plus polarisation (SEP)-level using a minimum orbital basis for single configuration interaction (MOBSCI) approach. Agreement between the measured and calculated DCSs was typically fair, although to obtain quantitative accord, the theory would need to incorporate even more channels into the MOBSCI.

The positron-hydrogen system at low energies

Calculations of low-energy positron-hydrogen and positronium-proton scattering using the close coupling method are reported at energies below the ionization threshold. The channel space included six hydrogen (1s, 2s, 2p, 3s, 3p and 3d) and six positronium (1s, 2s, 2p, 3s, 4s and 3p) states. Comparisons with more accurate calculations demonstrate that this model should give integrated cross sections accurate to 10%. Cross sections are computed with a fine energy mesh and a total of 11 resonances associated with the H(n=2) and Ps(n=2) thresholds have been identified and the resonance positions and widths determined. Calculations of the total cross section and the positronium formation cross section for positron-hydrogen scattering are consistent with the available experimental data. Cross sections for elastic scattering in the Ps(1s)-p entrance channel are dominated by a strong polarization potential and vary from 1000 pi a02 at threshold to 15 pi a02 at 1.0 Ryd. Cross sections for the Ps(1s)+p to e++H(nl) rearrangement collision are also reported since these provide baseline data relevant to experiments aimed at making antihydrogen atoms. Differential cross sections for elastic Ps(1s)-p and e+-H(1s) scattering and for electron transfer to the hydrogen atom ground state are also reported at selected energies.

Positron scattering from hydrogen atom embedded in weakly coupled plasma

The positron-hydrogen collision problem in weakly coupled plasma environment has been investigated by applying a formulation of the three-body collision problem in the form of coupled multi-channel two-body Lippmann-Schwinger equations. The interactions among the charged particles in the plasma have been represented by Debye-Huckel potentials. A simple variational hydrogenic wave function has been employed to calculate the partial-wave scattering amplitude. Plasma screening effects on various possible mode of fragmentation of the system e++H(1s) during the collision, such as 1s→1s and 2s→2s elastic collisions, 1s→2s excitation, positronium formation, elastic proton-positronium collisions, have been reported. Furthermore, a detailed study has been made on differential and total cross sections of the above processes in the energy range 13.6-350 eV of the incident positron.

Direct delay decomposition approach to synchronization of chaotic fuzzy cellular neural networks with discrete, unbounded distributed delays and Markovian jumping parameters

In this paper, the problem of synchronization of chaotic fuzzy cellular neural networks (FCNNs) with discrete, unbounded distributed delays and Markovian jumping parameters (MJPs) is investigated. Sufficient delay-dependent stability criteria are obtained in terms of linear matrix inequalities (LMIs) to ensure the chaotic delayed FCNNs to be stochastic asymptotically synchronous with the help of free-weighting matrix and some inequality techniques. The information of the delayed plant states can be taken into full consideration. Here, the delay interval is decomposed into two subintervals by using the tuning parameter ? such that 0 < ? < 1 . By developing a delay decomposition approach and constructing suitable Lyapunov-Krasovskii functional (LKF), sufficient conditions for synchronization are established for each subinterval. Numerical example and its simulations are provided to demonstrate the effectiveness and less conservatism of the derived results.

Delay-dependent H ∞ filtering for complex dynamical networks with time-varying delays in nonlinear function and network couplings

This paper investigates the H ∞ filtering problem for a class of continuous-time complex dynamical networks with time-varying delays in nonlinear function and network couplings. The aim of the addressed problem is to design a H ∞ filter against the exogenous disturbances, such that the filtering error system of complex dynamical networks is asymptotically stable and guarantees the desired H ∞ performance attenuation level. Based on the Lyapunov stability theory, suitable Lyapunov-Krasovskii functional is constructed in terms of Kronecker product, furthermore, new delay-dependent sufficient stability conditions are derived in terms of linear matrix inequalities by using reciprocal convex combination approach to obtain less conservative results. Finally, numerical examples are exploited to demonstrate the effectiveness of the proposed theoretical results. HighlightsUsing Kronecker product, novel Lyapunov-Krasovskii functionals are generated in a more compact form.Sufficient conditions on asymptotic stability of complex dynamical networks with H ∞ performance are derived.Reciprocally convex combination approach is used to provide less conservative results.Numerical simulations that are given to illustrate the designed filters are feasible and effective.