Autonomous coupled oscillators with hyperbolic strange attractors

We propose several examples of smooth low-order autonomous dynamical systems which have apparently uniformly hyperbolic attractors. The general idea is based on the use of coupled self-sustained oscillators where, due to certain amplitude nonlinearities, successive epochs of damped and excited oscillations alternate. Because of additional, phase sensitive coupling terms in the equations, the transfer of excitation from one oscillator to another is accompanied by a phase transformation corresponding to some chaotic map (in particular, an expanding circle map or Anosov map of a torus). The first example we construct is a minimal model possessing an attractor of the Smale-Williams type. It is a four-dimensional system composed of two oscillators. The underlying amplitude equations are similar to those of the predator-pray model. The other three examples are systems of three coupled oscillators with a heteroclinic cycle. This scheme presents more variability for the phase manipulations: in the six-dimensional system not only the Smale-Williams attractor, but also an attractor with Arnold cat map dynamics near a two-dimensional toral surface, and a hyperchaotic attractor with two positive Lyapunov exponents, are realized.     

Analytical and numerical study of coupled atomistic-continuum methods for fluids

The stability and convergence rate of coupled atomistic-continuum methods are studied analytically and numerically. These methods couple a continuum model with molecular dynamics through the exchange of boundary conditions in the continuum-particle overlapping region. Different coupling schemes, including velocity–velocity, flux–velocity, velocity–flux and flux–flux, are studied. It is found that the velocity–velocity and flux–velocity schemes are stable. The flux–flux scheme is weakly unstable. The stability of the velocity–flux scheme depends on the parameter T_c which is the length of the time interval between successive exchange of boundary conditions. It is stable when T_c is small and unstable when T_c is large. For steady-state problems, the flux–velocity scheme converges faster than the other coupling schemes.     

On a comparison principle for delay coupled systems with nonlocal and nonlinear boundary conditions

This paper is concerned with delay coupled systems of parabolic equations with nonlocal and nonlinear boundary conditions. For them, a new and general comparison principle is established, which is more general and useful than the existing results.     

Entanglement in Coupled Mesoscopic Circuits

A common two-mode squeezed state is one of the most important resources in quantum information processing of continuous variables. In this paper, a two-mode squeezed rotation-entangled state is obtained in coupled mesoscopic circuits. It is shown that instantaneously switching on the external sources may result in a two-mode squeezed state of the system, which actually arises from the coupling effect. The entanglement of the squeezed rotation-entangled state is studied. The degree of entanglement for coupled mesoscoipc circuit was calculated by using the technique of integration within an ordered product of operators. It is shown that the entanglement of the two-mode squeezed rotation-entangled state is different from that of the common squeezed state, for example, the degree of entanglement of the system, which is in the squeezed state, exist maximum value at a very low temperature.     

Improved analysis of an algorithm for the coupled task problem with UET jobs

The coupled task problem is to schedule n jobs, each one consisting of two subtasks with exact delay times between them, on a single machine. We derive a new lower bound for the problem variant with unit execution times and correct a previously published analysis.     

多光束全息互连元件效率的理论分析

多光束全息互连元件往往需要大量的耦合波方程才能描述。本文通过分析记录时生成的互调制光栅的性质及其对衍射的影响,对问题进行适当的简化。通过解不同条件下的耦合波方程、分别给出了多光束全息图在各种不同情况下的衍射效率的近似解析表达式,展示了衍射效率与各实验参量之间的关系。为进一步研究多光束全息互连元件的性质、比较各种条件下的效率以及各参量对总体效率的影响,提供了方便。     

Asymmetric transfer hydrogenation using amino acid derivatives; further studies and a mechanistic proposal

A series of investigations into the use of amino acid derivatives for the asymmetric catalysis of the transfer hydrogenation of ketones are presented. Based on the results observed, a mechanistic suggestion for the origin of the enantioselective induction is proposed.     

Investigation of phase-equivalent potentials by a halo transfer reaction

Using the supersymmetric quantum mechanics, we investigate the wave function-sensitive properties of the supersymmetric potentials which have received a lot of attention in the literature recently. We show that a superdeep potential and its phase-equivalent shallow-partner potential give very similar rms radius values for the weakly bound systems such as the deuteron and ¹¹Be nuclei. Although the corresponding eigenstates differ in the node-number, our investigation on the ¹¹Be(p, d )¹⁰Be single nucleon halo transfer reaction at 35 MeV show that also other physical quantities such as the cross-section angular distributions calculated using these wave functions reflect the nodal structure rather weakly. This lends support to two nearly equivalent treatments of the Pauli principle. Received: 15 May 2000 / Accepted: 14 September 2000