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We propose a cylindrical conformal transmitted metasurface for orbital angular momentum vortex wave generation. Formulas for calculating the phase distributions of cylindrical conformal transmitted metasurface is presented. A prototype of the proposed conformal transmitted metasurface is designed, fabricated and measured. Measured results shows that the proposed conformal transmitted metasurface can effectively generate vortex waves, which verifies the effectiveness of our method. The proposed method may pave the way of vortex wave generation with cylindrical conformal devices.

In this paper, we study lag synchronization between two coupled networks and apply two types of control schemes, including the open-plus-closed-loop (OPCL) and adaptive controls. We then design the corresponding control algorithms according to the OPCL and adaptive feedback schemes. With the designed controllers, we obtain two theorems on the lag synchronization based on Lyapunov stability theory and Barbalat's lemma. Finally we provide numerical examples to show the effectiveness of the obtained controllers and see that the adaptive control is stronger than the OPCL control when realizing the lag synchronization between two coupled networks with different coupling structures.

In this paper, we study anti-synchronization between two coupled networks where the node dynamics has an unknown system parameter. By designing adaptive and pinning control schemes, we realize the anti-synchronization. By Lyapunov stability theory, we obtain two theorems on the appearance of anti-synchronization. In addition, we derive a criterion for the pinning number of nodes. Finally we provide two numerical examples to show the effectiveness of our proposed control schemes. When the anti-synchronization is achieved, we successfully identify the unknown system parameter.

This paper discusses the conformal invariance by infinitesimal transformations of canonical Hamilton systems. The necessary and sufficient conditions of conformal invariance being Lie symmetrical simultaneously by the action of infinitesimal transformations are given. The determining equations of the conformal invariance are gained. Then the Hojman conserved quantities of conformal invariance by special infinitesimal transformations are obtained. Finally an illustrative example is given to verify the results.

We study the dynamics of the cubic–quintic nonlinear Schrodinger equation by the symplectic method. The behaviors of the equation are discussed with harmonically modulated initial conditions, and the contributions from the quintic term are discussed. We observe the elliptic orbit, homoclinic orbit crossing, quasirecurrence, and stochastic motion with different nonlinear parameters in this system. Numerical simulations show that the changing processes of the motion of the system and the trajectories in the phase space are various for different cubic nonlinear parameters with the increase of the quintic nonlinear parameter.

The low-frequency relaxation internal friction spectrum of La2CuO4+δ has been measured from -170 to 200°C in an automatic torsion apparatus at frequencies between 0.1 and 5.0 Hz. Three new relaxation processes are found with maxima, which are attributed to thermally activated diffusive jumps of oxygen atoms or vacancies in the oxygen sublattice, according to various activation enthalpies of three experimental runs. It is shown that the content of oxygen defect have important influences on the physical properties of La2CuO4+δ.

In this paper, we present a new integration algorithm based on the discrete Pfaff—Birkhoff principle for Birkhoffian systems. It is proved that the new algorithm can preserve the general symplectic geometric structures of Birkhoffian systems. A numerical experiment for a damping oscillator system is conducted. The result shows that the new algorithm can better simulate the energy dissipation than the R-K method, which illustrates that we can numerically solve the dynamical equations by the discrete variational method in a Birkhoffian framework for the systems with a general symplectic structure. Furthermore, it is demonstrated that the results of the numerical experiments are determined not by the constructing methods of Birkhoffian functions but by whether the numerical method can preserve the inherent nature of the dynamical system.

We investigate the effect of an external periodic modulation on the one-dimensional (1D) Bose—Einstein condensate with harmonic trapping potential. By numerically solving the Gross—Pitaevskii equation with symplectic algorithm, the nonlinear resonance phenomenon is shown and the corresponding Fourier spectrum is given. The autoresonance phenomenon is also presented under almost periodic external modulation, and it shows that the condensate eventually evolves into quasi-periodic oscillation.

The problem of transforming autonomous systems into Birkhoffian systems is studied. A reasonable form of linear autonomous Birkhoff equations is given. By combining them with the undetermined tensor method, a necessary and sufficient condition for an autonomous system to have a representation in terms of linear autonomous Birkhoff equations is obtained. The methods of constructing Birkhoffian dynamical functions are given. Two examples are given to illustrate the application of the results.

The variational integrators of autonomous Birkhoff systems are obtained by the discrete variational principle. The geometric structure of the discrete autonomous Birkhoff system is formulated. The discretization of mathematical pendulum shows that the discrete variational method is as effective as symplectic scheme for the autonomous Birkhoff systems.

This paper constructs an almost-Poisson structure for the non-self-adjoint dynamical systems, which can be decomposed into a sum of a Poisson bracket and the other almost-Poisson bracket. The necessary and sufficient condition for the decomposition of the almost-Poisson bracket to be two Poisson ones is obtained. As an application, the almost-Poisson structure for generalised Chaplygin's systems is discussed in the framework of the decomposition theory. It proves that the almost-Poisson bracket for the systems can be decomposed into the sum of a canonical Poisson bracket and another two noncanonical Poisson brackets in some special cases, which is useful for integrating the equations of motion.

The local temperature effect on strangeness enhancement in relativistic heavy ion collisions is discussed in the framework of the thermal model in which the K+/h+ ratio becomes smaller with increasing freeze-out temperature. Considering that most strangeness particles of final-state particles are from the kaon meson, the temperature effect may play a role in strangeness production in hot dense matter where a slightly different temperature distribution in different areas could be produced by jet energy loss. This phenomenon is predicted by thermal model calculation at RHIC energy. The Ξ−/ ratio in central Au+Au collisions at 200 GeV from the thermal model depends on the freeze-out temperature obviously when γS is different. It should be one of the reasons why strangeness enhancements of Ξ and are different though they include two strange quarks. These results indicate that thermodynamics is an important factor for strangeness production and the strangeness enhancement phenomenon.