HOVERING ORBITS DESIGN FOR PERTURBED ASTEROIDS WITH PARAMETRIC EXCITATION RESONANCE 1)

本文将太阳引力摄动视为受摄不规则小行星系统的组成部分,借鉴非线性振动理论中参数激励共振的概念,创新性地设计了不规则小行星平衡点附近稳定的悬停观测轨道.为了同时考虑不规则小行星引力和太阳引力, 本文采用受摄粒杆模型描述系统.通过对未扰系统平衡点以及固有频率的分析, 给出系统存在参激共振轨道的条件.再以第二类参激主共振和1:3内共振为例,采用多尺度方法求得参数激励共振轨道的稳态解, 并对稳态解的稳定性进行判断.通过受摄小行星系统的幅频响应曲线以及力频响应曲线分析了系统的非线性特性以及参数激励效应.此外, 对内共振引起的长短周期能量转移现象进行了分析.本文的研究成果可以拓展现有小行星系统周期轨道族设计方法.     

Simulation of beam optics for ~(12)C+~(12)C scattering of RCNP by using Monte Carlo method

The Monte Carlo method is used to simulate the beam optics of the WS beam line of RCNP, Osaka University in order to know the effect of collimators on the beam line to control the beam spot. According to the simulation, we do not need to use the collimator to cut the beam and the beam angular resolution can be better than 0.05° in achromatic mode. In the present paper, the actual beam condition during the beam adjustment is listed. The accelerator can provide a 12 C beam in achromatic mode and the angular resolution σ=0.7775 mrad ±0.0030 mrad.     

Mechanical analogues of spin Hamiltonians and dynamics

Bloch et al. mapped the precession of the spin-half in a magnetic field of variable magnitude and direction to the rotations of a rigid sphere rolling on a curved surface utilizing SU(2)–SO(3)$\mathit{SU}(2)\text{–}\mathit{SO}(3)$ isomorphism. This formalism is extended to study the behaviour of spin–orbit interactions and the mechanical analogy for Rashba–Dresselhauss spin–orbit interaction in two dimensions is presented by making its spin states isomorphic to the rotations of a rigid sphere rolling on a ring. The change in phase of spin is represented by the angle of rotation of sphere after a complete revolution. In order to develop the mechanical analogy for the spin filter, we find that perfect spin filtration of down spin makes the sphere to rotate at some unique angles and the perfect spin filtration of up spin causes the rotations with certain discrete frequencies.     

Effects of the spin–orbit coupling on the vacancy-induced magnetism on the honeycomb lattice

The local magnetism induced by vacancies in the presence of the spin–orbit interaction is investigated based on the half-filled Kane–Mele–Hubbard model on the honeycomb lattice. Using a self-consistent mean-field theory, we find that the spin–orbit coupling will enhance the localization of the spin moments near a single vacancy. We further study the magnetic structures along the zigzag edges formed by a chain of vacancies. We find that the spin–orbit coupling tends to suppress the counter-polarized ferrimagnetic order on the upper and lower edges, because of the open of the spin–orbit gap. As a result, in the case of the balance number of sublattices, it will suppress completely this kind of ferrimagnetic order. But, for the imbalance case, a ferrimagnetic order along both edges exists because additional zero modes will not be affected by the spin–orbit coupling.     

Effects of Rashba spin–orbit coupling interface on the orientation-dependent conductance in ferromagnet/spin-triplet superconductor junction

We study theoretically the tunneling charge conductance in ferromagnet/spin-triplet superconductor junction with the spin–orbit coupling interface. It is shown the symmetry of the conductance about the relative angle between the magnetization in ferromagnet and the d-vector in superconductor is broken due to the presence of the interfacial Rashba spin–orbit coupling. We present the conductance for various cases of the angle. For each angle, the spin-active mechanism provided by the interface is investigated. The interface effects for different spin polarization in the ferromagnet is also considered.     

Analysis of queuing delay in optical space network on LEO satellite constellations

Low earth orbit (LEO) satellite constellations using laser inter-satellite links (ISLs) are recognized as a promising technology to provide global broadband network services. In this paper, the queuing delay model of an optical space network built on LEO satellite constellations is established. It is assumed that the optical space network employs wavelength division multiplexing ISLs with wavelength routing technology to communication satellites and makes routing decisions. With consideration of the network task characterizations such as distribution of task arrival time and task holding duration, simulation experiment results are analyzed and the expression of optical space network queuing delay is given. Both theoretical analysis and simulation results show that features of queuing delay vary with distribution characterizations of the network tasks. It is hoped that the study can be helpful to evaluate the design of constellation networking.     

Nonreciprocal scattering by stacked nonlinear magneto-active semiconductor layers

The combinatorial frequency generation by the periodic stacks of magnetically biased semiconductor layers has been modelled in a self-consistent problem formulation, taking into account the nonlinear dynamics of carriers. It is shown that magnetic bias not only renders nonreciprocity of the three-wave mixing process but also significantly enhances the nonlinear interactions in the stacks, especially at the frequencies close to the intrinsic magneto-plasma resonances of the constituent layers. The main mechanisms and properties of the combinatorial frequency generation and emission from the stacks are illustrated by the simulation results, and the effects of the individual layer parameters and the structure arrangement on the stack nonlinear and nonreciprocal response are discussed.     

束流诊断虚拟加速器环境开发

为了更好的测试控制方法和开发上层控制软件,本文提出了一种基于ELEGANT和SDDS Toolkit的虚拟加速器环境。在这个虚拟环境下,可以将底层物理模拟软件与上层控制软件通过EPICS控制通道及Matlab脚本进行数据分析及处理。本文描述了在该虚拟加速器环境中束流参数测量和轨道控制等软件的开发和测试,并探讨了该虚拟加速器的设计理念和未来可能的应用。