Semiunitary Transforrnation and Isospectral Hamiltonians in Arbitrary Dimensional Space

By means of the complex Clifford algebra, a new realization of multi-dimensional semiunitary transformation is put forward and then applied to studying the isospectrality of nonrelativistic Hamiltonians of multi-dimensional quantum mechanical systems, in which the generalized Pauli coupling interaction and spin-orbit coupling interaction appear naturally. Moreover, it is shown that the semiunitary operators, together with the Hamiltonian of quantum mechanical system, satisfy the polynomially-deformed angular momentum algebra.``     

A New Method for the Atomic Ground-State Energy in the Screened Coulomb Potential

The new method proposed recently by Friedberg,Lee and Zhao is applied to the derivation of the atomic ground-state energy with the inclusion of the screening effect.The present results are compared with those obtained in the pure Coulomb potential and by the variational approach.The overall good results are obtained with this new method.     

Semiunitary Transformation and Isospectral Hamiltonians in Arbitrary Dimensional Space

By means of the complex Clifford algebra, a new realization of multi-dimensional semiunitary transformation is put forward and then applied to studying the isospectrality of nonrelativistic Hamiltonians of multi-dimensional quantum mechanical systems, in which the generalized Pauli coupling interaction and spin-orbit coupling interaction appear naturally. Moreover, it is shown that the semiunitary operators, together with the Hamiltonian of quantum mechanical system, satisfy the polynomially-deformed angular momentum algebra.     

Spin-Flip and Elastic Processes in Slow Collisions of Mesic Atoms

The reduced adiabatic hyperspherical (RAHS) basis suggested previously is used for the calculation of elastic and spin-flip cross sections in the processes (aμ) _F + a → (aμ) _F′ + a, a = (p, d, t), for collision energies 10⁻³ ≤ ε ≤ 10² eV. The rapid convergence of the method is demonstrated. A comparison of the obtained results with previous ones is presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

漂浮基空间机械臂关节空间轨迹的鲁棒自适应跟踪控制

本文讨论了具有不确定系统参数的漂浮基空间机械臂系统的控制问题,由于截体的位置与姿态均不变控制,空间机械臂系统的控制方程失去了关于系统惯性参数的线性性质,给控制系统设计带来极大的困难,基于增广变量的思想,我们克服了上述难点,保持了控制方程关于系统惯性参数的线性关系;在此基础上,针对系统中机械臂参数不确定,载荷参数未知的情况,提出了关节空间轨迹追踪的鲁棒自适应控制方案,并应用Lyapunov直接方法对上述控制方案的渐近稳定性条件作了证明,提出的控制方案适用于空间站舱内机械手控制系统设计,仿真运算证实了该方法的有效性。     

非线性问题的参数迭代求解法

提出一种对非线性问题的参数迭代求解法,算例表明,其一次迭代解便有很好的精度.     

Modelling of rib waveguide bends for sensor applications

Wave propagation through curved bends in integrated optical waveguides is governed by the evanescent field and the radiation loss of the eigenmodes. Since these parameters are influenced by the refractive index of the surrounding medium, circular bends in rib waveguides have been successfully employed as chemical sensors for liquids and gases. In this paper the electromagnetic field, the refractive index and the radiation loss of the eigenmodes are precisely determined by a fully vectorial approach based on the method of lines. An axial discretization and Bessel functions of complex order are employed for the rigorous computation of the evanescent field. The intensity distributions of the first modes in a rib waveguide are presented. The influence of the rib height on the sensitivity of the modal index to the refractive index of the surrounding medium is investigated. The results are useful for the optimization of the sensor design.     

The role of meson retardation in the NN interaction above pion threshold

A model is developed for the hadronic interaction in the two-nucleon system above pion threshold which is based on meson, nucleon and Δ degrees of freedom and which includes full meson retardation in the exchange operators. For technical reasons, the model allows maximal one meson to be present explicitly. Thus the Hilbert space contains besides NN and NΔ also configurations consisting of two nucleons and one meson. For this reason, only two- and three-body unitarity is obeyed, and the model is suited for reactions in the two-nucleon sector, where only one pion is produced or absorbed. Starting from a realistic pure nucleonic retarded potential, which had to be renormalized because of the additional π and Δ degrees of freedom, a reasonable fit to experimental NN-scattering data could be achieved.     

Thermodynamical irreversible approach for the stellar pulsation problem

In this paper, the stellar pulsation theory is reformulated following an irreversible thermodynamic approach (Lavenda, Thermodynamics of Irreversible Processes, Denver, New York, 1993). A general stability criterion and a thermodynamic Langrangian for the pulsating star problem are obtained using a variational method (Sicardi and Ferro Fontán, Phys. Lett. 113A (1958) 263; Sicardi et al., J. Math. Phys. 32 (1991) 1350). This formulation, based on the calculation of a free energy excess function, is applied to the adiabatic, non-adiabatic, radial and non-radial cases and, as a result, the already known energy principles are obtained as particular cases of the general stability criterion mentioned above. Eigenvectors and eigenvalues can be calculated in a systematic way from the thermodynamic Lagrangian obtained for the general dissipative case (being independent of the adiabatic one). This allows a better determination of periods and oscillation frequencies.     

具有物理背景的高维Painlevé可积模型

提出了一种求解任意维数非线性模型的“M?bious”变换下不变的渐进展开方法,并可同时获得许多新的与原模型有着相同维数的Painlevé可积模型.取(2+1)维KdV-Burgers(KdVB)方程和Kadomtsev-Petviashvili(KP)方程为具体例子,获得了一些新的具有Painlevé性质的高维“M?bious”变换下不变的方程及原模型的近似解.在某些特殊情况下,某些近似解可以成为精确解 关键词： 高维可积模型 “M?bious”不变 近似方法