非傍轴矢量异常空心光束的传输特性

 将Cai提出的异常空心光束的理论模型推广到非傍轴范畴,推导出非傍轴矢量异常空心光束传输的解析表达式,用以研究它在自由空间中的传输特性。研究表明,异常空心光束在传输过程中光束形状会发生变化。与高斯光束不同,非傍轴异常空心光束傍轴近似成立条件依赖于传输距离,这与异常空心光束光强分布随传输距离的变化有关。非傍轴异常空心光束远场的光束质量可用桶中功率来描述,桶中功率随f参数(波长与束腰宽度的比值)的增大而减小。     

高斯光束通过像散透镜后光束参数的变化

以二阶矩和环围功率作为束宽定义,对高斯光束通过像散透镜后光束参数,包括束宽和远场发散角作了解析和数值研究。结果表明：因像散引入束宽和远场发散角的相对误差与像散因子、瑞利尺寸、透镜焦距有关。对于束宽而言,相对误差还与传输距离z有关。在几何焦面处x和y方向束宽的相对误差相等。     

HIRFL-CSRE 脉冲堆积式高频数字低电平系统

为突破传统束流堆积方式瓶颈、提高重离子流强,兰州重离子加速器冷却储存实验环（HIRFL-CSRe）将采用移动式脉冲堆积方案（Moving Barrier Bucket）。该方案要求高频系统能产生高精度的单正弦电压,然而由于Barrier Bucket（BB）电压的宽带特性以及高频系统的非线性,高频腔内的BB电压存在着严重的失真问题。针对此问题,在全面分析了BB电压波形特性以及高频系统的频率响应的基础上,设计了BB电压预失真前馈控制方案,并详细描述了该方案的原理、仿真、软硬件设计以及实际测试结果。研究成果将应用于HIRFL-CSRe的BB束流堆积实验以及十二五强流重离子加速器（HIAF）的BB堆积模式。     

像散透镜对高斯光束的变换特性

基于广义惠更斯-菲涅尔衍射积分,并考虑了像散的影响,对高斯光束通过像散透镜后的传输特性作了解析研究,以光束传输因子和桶中功率为参数分析了像散高斯光束的光束质量,并以数值计算例加以说明。     

Scheduling algorithm for the multiple rovers' access to single orbiter on the Mars relay communication links

The Mars relay communication services have played an important role on the scientific data transmission for several Mars surface exploration missions. However, such technologies based on CCSDS Proximity‐1 protocols only support one single user's access to orbiter at one relay communication session. In future deep space missions, there would be more rovers and facilities on the Mars surface, which requires a multiple access method with high efficiency and low resource occupation. In this article, we propose a distributed serial scheduling structure as "multiple leaky buckets + token bucket" and a scheduling algorithm as "queue equilibrium based proportional fair," in order to improve the multiple access performance on the comprehensive merits of fair access, data transfer throughput, and queue equilibrium. The mathematical model is constructed to validate our new scheduling structure and algorithm, and the multiple attribute decision‐making (MADM) method is used to compare our algorithm with the other three most frequently used algorithms as maximum rate, time polling, and proportional fair. Simulation results show that our scheduling structure and the new scheduling algorithm could find balance with fairness, throughput and queue equilibrium, which gets the best performance in all the four scheduling algorithms in the Mars relay communications case.     

PERFORMANCE OF ACCESS RATE CONTROL FOR CORRELATED SOURCES IN HIGH-SPEED NETWORKS: SPECTRAL ANALYSIS

In this paper we study the performance trade-offs of leaky-bucket control in a high speed network with correlated sources. The emphasis is placed on the interrelationship between access control queueing and network queueing, as affected by degrees of control in response to differing input power spectrum characterizing the source correlations. Both stochastic and deterministic analyses are developed. Whereas the stochastic analysis based on multi-state Markov modulated sources provides exact performance measures of the access rate control in random traffic environment, the deterministic analysis based on sinusoidal sources complements the stochastic analysis, leading to good engineering insights into the control performance in the complex scenarios where the stochastic analysis is intractable. Interesting observations are made between the control performance and the low-frequency input power. In the stochastic analysis, we use a novel technique to characterize a rather general class of input power spectrum and are able to derive not only the power spectrum of the leaky-bucket controlled source but also the distribution of a network queue fed by the controlled source.     

基于FPGA的多通道流量控制研究与实现

在网络通信系统中,流量控制器是实现通信业务量管制的关键电路,用于监视和控制信元的传输速率。针对多个连接共享带宽的流量控制使用需求,在分析虚调度算法的基础上,结合FPGA并行计算的特点,提出一个基于FP-GA的实时响应多通道并行流量控制IP核的实现方法,进行了仿真测试,给出了资源消耗和系统最高工作频率等结果。该IP核可应用于ATM和IP网络的流量控制。     

超高斯光束经光阑球差透镜后的光束质量评价

以桶中功率(PIB)、β参数和η参数为激光光束质量评价参数,对超高斯光束经有方环光阑球差透镜后的光束质量作了详细的研究。大量数值计算和物理分析表明,超高斯光束经有方环光阑透镜后的光束质量与方环遮拦比、透镜球差和超高斯光束的阶数等因素有关。采用适当的负球差透镜,在实际焦面上可得到最大的PIB,η值和最小的β值,从而获得比无球差透镜更好的光束质量,甚至使β1。     

矢量非傍轴厄米-拉盖尔-高斯光束的光束质量

基于矢量Rayleigh-Sommerfeld衍射积分，推导出矢量非傍轴圆偏振厄米-拉盖尔-高斯(HLG)光束的远场解析表达式.矢量非傍轴圆偏振高斯光束可作为一般公式的特例给出.将桶中功率(PIB)概念推广到非傍轴范畴，用以描述矢量非傍轴光束的远场光束质量，其中光强用时间平均坡印廷矢量的z分量取代.数值计算和分析表明，矢量非傍轴HLG光束的PIB不仅与束腰宽度与波长之比w₀/λ有关，而且还与α参数，模指数n和m以及所取桶的尺寸有关. 关键词： 矢量非傍轴厄米-拉盖尔-高斯光束 矢量Rayleigh-Sommerfeld衍射积分 桶中功率