• Issue front cover thumbnail

      Volume 81, Issue 5

      November 2013,   pages  727-892

    • Lag synchronization of chaotic systems with time-delayed linear terms via impulsive control

      Ranchao Wu Dongxu Cao

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      In this paper, the lag synchronization of chaotic systems with time-delayed linear terms via impulsive control is investigated. Based on the stability theory of impulsive delayed differential equations, some sufficient conditions are obtained guaranteeing the synchronized behaviours between two delayed chaotic systems. Numerical simulations on time-delayed Lorenz and hyperchaotic Chen systems are also carried out to show the effectiveness of the proposed scheme. Note that under the scheme the chaotic system is controlled only at discrete time instants, and so it reduces the control cost in real applications.

    • The integrability of an extended fifth-order KdV equation with Riccati-type pseudopotential

      Yun-Hu Wang Yong Chen

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      The extended fifth-order KdV equation in fluids is investigated in this paper. Based on the concept of pseudopotential, a direct and unifying Riccati-type pseudopotential approach is employed to achieve Lax pair and singularity manifold equation of this equation. Moreover, this equation is classified into three categories: extended Caudrey–Dodd–Gibbon–Sawada–Kotera (CDGSK) equation, extended Lax equation and extended Kaup–Kuperschmidt (KK) equation. The corresponding singularity manifold equations and auto-Bäcklund transformations of these three equations are also obtained. Furthermore, the infinitely many conservation laws of the extended Lax equation are found using its Lax pair. All conserved densities and fluxes are given with explicit recursion formulas.

    • Analytical travelling wave solutions and parameter analysis for the $(2+1)$-dimensional Davey–Stewartson-type equations

      Jianping Shi Jibin Li Shumin Li

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      By using dynamical system method, this paper considers the $(2+1)$-dimensional Davey–Stewartson-type equations. The analytical parametric representations of solitary wave solutions, periodic wave solutions as well as unbounded wave solutions are obtained under different parameter conditions. A few diagrams corresponding to certain solutions illustrate some dynamical properties of the equations.

    • A generalized exp-function method for multiwave solutions of sine-Gordon equation

      Sheng Zhang Jian Wang Au-Xue Peng Bin Cai

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      In this paper, the exp-function method is generalized to sine-Gordon (sG) equation and single-, double- and three-wave solutions are obtained. It is shown that the generalized exp-function method combined with appropriate anstaz may provide a straightforward, effective and alternative method for constructing multiwave solutions of some nonlinear partial differential equations.

    • Coupling constant in dispersive model

      R Saleh-Moghaddam M E Zomorrodian

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      The average of the moments for event shapes in $e^{+} e^{-} \rightarrow$ hadrons within the context of next-to-leading order (NLO) perturbative QCD prediction in dispersive model is studied. Moments used in this article are $\langle 1 - T \rangle, \langle \rho \rangle, \langle B_{T} \rangle$ and $\langle B_{W} \rangle$. We extract $\alpha_{s}$, the coupling constant in perturbative theory and α0 in the non-perturbative theory using the dispersive model. By fitting the experimental data, the values of $\alpha_{s} (M_{Z^{\circ}}) = 0.1171 \pm 0.00229$ and $\alpha_{0} (\mu_{I} = 2{\text{GeV}}) = 0.5068 \pm 0.0440$ are found. Our results are consistent with the above model. Our results are also consistent with those obtained from other experiments at different energies. All these features are explained in this paper.

    • Next-to-next-to-leading order calculation of the strong coupling constant $\alpha_{s}$ by using moments of event-shape variables

      Samira Shoeibi Mohsenabadi Mohammad Ebrahim Zomorrodian

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      The next-to-next-to-leading order (NNLO) quantum chromodynamics (QCD) correction to the first three moments of the four event-shape variables in electron–positron annihilation, the thrust, heavy jet mass, wide, and total jet broadening, is computed. It is observed that the NNLO correction gives a better agreement between the theory and the experimental data. Also, by using the above observables, the strong coupling constant ($\alpha_{s}$) is determined and how much its value is affected by the NNLO correction is demonstrated. By combining the results for all variables at different centre-of-mass energies $\alpha_{s} (M_{Z^{\circ}}) = 0.1248 \pm 0.0009 ({\text{exp.}})_{-0.0144}^{+0.0283} ({\text{theo.}})$ is obtained.

    • The asymptotic D-state to S-state ratio of triton

      Hossen Sadeghi Reza Pourimani Hassan Khalili

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      At low energies, an effective field theory (EFT) with only contact interactions as well as three-body forces allow a detailed analysis of renormalization in a non-perturbative context and uncovers novel asymptotic behaviour. Triton as a three-body system, based on the EFT have been previously shown to provide representative binding energies, charge radii, S-wave scattering amplitude and asymptotic normalization constants for the 3H bound state system. Herein, EFT predictions of the asymptotic D-state to S-state ratio of triton are calculated to more fully evaluate the adequacy of the EFT model. Manifestly model-independent calculations can be carried out to high orders, leading to high precision.

    • Fission characteristics of $^{216}$Ra formed in heavy-ion induced reactions

      Hadi Eslamizadeh

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      A Kramers-modified statistical model is used to calculate the cross-section of the evaporation residue, fission cross-section, average pre-fission multiplicities of protons and $\alpha$-particles for $^{216}$Ra formed in $^{19}{\text{F}} + ^{197}{\text{Au}}$ reactions and results are compared with the experimental data. To calculate these quantities, the effects of temperature and spin $K$ about the symmetry axis have been considered in the calculations of the potential energy surfaces and the fission widths. It is shown that the results of the calculations using values of the temperature coefficient of the effective potential $k = 0.008 \pm 0.003$ MeV$^{−2}$ and scaling factor of the fission-barrier height $r_{s} = 1.004 \pm 0.002$ are in good agreement with the experimental data.

    • Fundamental modes of new dispersive SH-waves in piezoelectromagnetic plate

      A A Zakharenko

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      Fundamental modes of new dispersive shear-horizontal (SH) acoustic waves propagating in the (6 mm) piezoelectromagnetic plate are studied. These SH-waves can propagate when the following boundary conditions are exploited for both the upper and lower surfaces of the plate: (1) when the surfaces are mechanically free, electrically and magnetically closed and (2) when the surfaces are mechanically free, electrically and magnetically open. The SH-waves depend on the electromagnetic wave speed $V_{\text{EM}} = 1/\sqrt{(\varepsilon \mu)}$ and can only exist when the electromagnetic constant $\alpha \neq 0$. The calculations (first evidence) were performed for the PZT-5H–Terfenol-D which is a composite with a large value of $\alpha$. The limit cases of large values of $\alpha (\alpha^{2} = 0.5\varepsilon \mu, \alpha^{2} = 0.9\varepsilon \mu)$, and $\alpha^{2} = 0.99\varepsilon \mu$) are studied because they satisfy the limitation condition of $\alpha^{2} < \varepsilon \mu$.

    • Development of online quasimonochromatic X-ray backlighter for high energy density physics studies

      S Chaurasia P Leshma D S Munda

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      Monochromatic X-ray backlighting has been employed with great success in various laser plasma experiments including inertial confinement fusion (ICF) research. However, implementation of a monochromatic backlighting system typically requires extremely high quality spherically bent crystals which are difficult to manufacture and are also expensive. In this paper, we present a quasimonochromatic X-ray backlighting system using flat thallium acid pthalate (TAP) crystal. The detailed characterization of the system is discussed. The X-ray backlighter spectral range is caliberated using Cu spectrum in the spectral range 7–9 Å (1.38–1.77 keV). Gold plasma produces continuous X-ray spectrum (M band) in this range. The spectral, spatial and temporal resolutions of the system measured are 30 mÅ, 50 $\mu$m and 1.5 ns respectively. The spectral width of the X-ray pulse is 2 Å ($\Delta E$ = 0.39 keV).

    • Boson bound states in the $\beta$-Fermi–Pasta–Ulam model

      Xin-Guang Hu Ju Xiang Zheng Jiao Yang Liu Guo-Qiu Xie Ke Hu

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      The bound states of four bosons in the quantum $\beta$-Fermi–Pasta–Ulam model are investigated and some interesting results are presented using the number conserving approximation combined with the number state method. We find that the relative magnitude of anharmonic coefficient has a significant effect on forming localized energy in the model, and the wave number plays an important role in forming different bound states. The signature of the quantum breather is also set up by the square of the amplitudes of the corresponding eigenvectors in real space.

    • Effective thermal conductivity of condensed polymeric nanofluids (nanosolids) controlled by diffusion and interfacial scattering

      M R Nisha M S Jayalakshmy J Philip

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      Thermal properties of polymeric nanosolids, obtained by condensing the corresponding nanofluids, are investigated using photothermal techniques. The heat transport properties of two sets of polyvinyl alcohol (PVA) based nanosolids, TiO2/PVA and Cu/PVA, prepared by condensing the respective nanofluids, which are prepared by dispersing nanoparticles of TiO2 and metallic copper in liquid PVA, are reported. Two photothermal techniques, the photoacoustic and the photopyroelectric techniques, have been employed for measuring thermal diffusivity, thermal conductivity and specific heat capacity of these nanosolids. The experimental results indicate that thermal conduction in these polymer composites is controlled by heat diffusion through the embedded particles and interfacial scattering at matrix–particle boundaries. These two mechanisms are combined to arrive at an expression for their effective thermal conductivity. Analysis of the results reveals the possibility to tune the thermal conductivity of such nanosolids over a wide range using the right types of nanoparticles and right concentration.

    • Magnetic field effect on state energies and transition frequency of a strong-coupling polaron in an anisotropic quantum dot

      Wei Xiao Jing-Lin Xiao

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      By employing a variational method of the Pekar-type, which has different variational parameters in the $x–y$ plane and the $z$-direction, we study the ground and the first excited state energies and transition frequency between the ground and the first excited states of a strong-coupling polaron in an anisotropic quantum dot (AQD) under an applied magnetic field along the $z$-direction. The effects of the magnetic field and the electron–phonon coupling strength are taken into account. It is found that the ground and the first excited state energies and the transition frequency are increasing functions of the external applied magnetic field. The ground state and the first excited state energies are decreasing functions, whereas transition frequency is an increasing function of the electron–phonon coupling strength. We find two ways of tuning the state energies and the transition frequency: by adjusting (1) the magnetic field and (2) the electron–phonon coupling strength.

    • Phase transition properties of a cylindrical ferroelectric nanowire

      Wang Ying Yang Xiong

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      Based on the transverse Ising model (TIM) and using the mean-field theory, we investigate the phase transition properties of a cylindrical ferroelectric nanowire. Two different kinds of phase diagrams are constructed. We discuss systematically the effects of exchange interactions and the transverse field parameters on the phase diagrams. Moreover, the cross-over features of the parameters from the ferroelectric dominant phase diagram to the paraelectric dominant phase diagram are determined for the ferroelectric nanowire. In addition, the polarizations of the surface shell and the core are illustrated in detail by modifying the TIM parameters.

    • Elastic and piezoelectric properties, sound velocity and Debye temperature of (B3) boron–bismuth compound under pressure

      S Daoud N Bioud N Lebgaa

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      Pseudopotential plane-wave method (PP–PW) based on density functional theory (DFT) and density functional perturbation theory (DFPT) within the Teter and Pade exchangecorrelation functional form of the local spin density approximation (LSDA) is applied to study the effect of pressure on the elastic and piezoelectric properties of the (B3) boron–bismuth compound. The phase transition, the independent elastic stiffness constants, the bulk modulus, the direct and converse piezoelectric coefficients, the longitudinal, transverse, and average sound velocities, and finally the Debye temperature under pressure are studied. The results obtained are generally lower than the available theoretical data (experimental data are not available) reported in the literature.

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