一种改进的阵列天线方向图主波束快速赋形算法

改进的基于自适应天线阵理论的主波束赋形快速算法,可对任意阵列快速完成主波束赋形和旁瓣电平的控制.该算法通过局域权函数的迭代来减小综合方向图和期望方向图在主波束上的差别,旁瓣电平的控制可以通过在旁瓣峰值区域处加干扰来快速达到.该方法对主波束方向、宽度、形状和增益的控制非常成功.给出了一些算例说明这种算法的有效性.     

基于脉冲整形的激发双重态间的相干布局操控

为了实现红外飞秒脉冲的整形及调控,采用4f系统相位控制技术,实验搭建了脉冲整形装置,并利用整形脉冲对铷原子体系中激发双重态间的相干布居转移进行操控。结果表明,控制抽运脉冲的附加相位,可实现双重态中上激发态的饱和布居,通过修改附加相位函数可将上、下激发态的布居数反转。整形脉冲同样适用于其它的原子和分子系统的相干布居转移的操控。     

抑制OFDM信号PAPR的改进脉冲整形

脉冲整形(PS)技术是一种有效可行的针对OFDM信号的PAPR抑制方法,它可以对发射信号进行频谱整形,降低系统误码率(BER),还可以用来抑制信号的峰均比,但不同的整形脉冲波形具有不同峰均比(PAPR)抑制性能和系统BER。提出一种改进的奈奎斯特脉冲,可以提高OFDM信号PAPR的抑制性能,同时不降低系统的BER,频带利用率高。仿真结果表明,其综合性能明显优于传统的升余弦和反转指数脉冲,是一种低复杂度的有效解决方案。     

利用集成光学调制器实现ICF固体激光驱动器中激光脉冲任意整形 Ⅱ.集成光学调制器

本文利用集成光学和光纤技术制作了集成光学调制器,驱动调制器的电压仅为４伏,配之以高稳定的、ＬＤ泵浦的单纵模振荡源和任意整形电脉冲源,大大提高了ＩＣＦ固体激光驱动器前级整形系统对激光脉冲整形的稳定性和灵活性．     

雷达信号成形规律的样本体系描述方法

针对多功能雷达工作在搜索方式时,其工作模式的转换以及同一模式下的脉冲信号均有规律可循的工作特点,提出一种基于雷达信号成形规律的样本体系描述技术。该方法利用多功能雷达工作模式的转换规律和脉冲本身的时频域参数变化规律,建立搜索模式转换样本、脉冲样本图和样本脉冲的层级数学模型,对多功能雷达脉冲信号成形规律进行提取和准确描述。仿真实验表明,样本体系描述技术不仅能够提取其对应的复杂体制雷达工作模式和脉冲信号,而且对噪声环境具有较好的适应能力。     

Control of an overlap-type proportional directional control valve using input shaping filter

In a hydraulic control system (herein, termed a major control loop), a proportional directional control (PDC) valve with spool position feedback may work in a minor (or inner) control loop. In this study the authors propose control designs to improve the performance of the PDC valve control loop (a minor control loop). At first, the mathematical model for the PDC valve is developed through an experimental identification process. Then, a dead-zone compensator that facilitates jumping of the overlap zone in spool/sleeve combination is devised and applied. A reference input following controller (including PI-D and feed-forward controller) that enables robust control of the PDC valve under disturbances is devised using the pole placement method and the zero placement method. Subsequently, an input shaping filter is incorporated into the devised control system to improve the reference following characteristic in high frequency range. Finally, the effectiveness of the proposed control design is verified experimentally.     

Influence of Shaping Condition on Etherification Performance of Hβ Zeolite

Etherification reaction of FCC light gasoline over Hβ zeolite was investigated to decrease the light olefins in motor gasoline while enhancing octane. Etherification activity of several molecular sieve catalysts for FCC light gasoline was studied in a fixed-bed reactor. The influence of pore-enlarging agent (PEG) with different molecular weight, binder (γ-Al₂O₃), and peptizing agent (HNO₃) in the shaping process on etherification activity of Hβ zeolite was studied. The impregnating ways of precursor of oxides and the order of extruding and impregnating were also investigated. The results show that the activity of extruded Hβ zeolite before impregnating precursor of oxides is higher than the reverse order. The best shaping condition obtained was PEG-4000 10%, γ-Al₂O₃ 20%, and HNO₃ 10%. At the optimal reaction condition, the conversion of tert-olefins reached the peak. 62.93%, the yield of TAME, is also high and the technology can be applied to industry as well.     

一种对任意线阵天线的主波束赋形方法

基于自适应天线阵理论,给出了一种用于任意线阵天线的主波束赋形算法.该方法通过迭代获得一组最优权值,用来减小加权赋形方向图和期望方向图在主波束上的差别,同时将旁瓣电平降低到期望值.一些算例充分说明了这种算法的有效性.该算法可以有效的控制主波束方向、宽度、形状和旁瓣电平.     

基于Rayleigh衰落信道下LDPC编码的星座成形

针对消息在信道传输过程中的成形损耗问题,提出了一种在Rayleigh衰落信道下基于低密度奇偶校验(Low-Density Parity-Check, LDPC)编码的星座成形系统。该方法基于脉幅调制(Pulse Amplitude Modulation, PAM)下的星座图,通过在发送端加入一个成形编码器(作用是提高输出比特为0的概率),使得星座图中低能量的符号比高能量的符号更容易被选中,从而提高成形增益。并且在解调器和译码器之间进行迭代译码,进一步提高了系统的性能。理论分析和仿真结果表明,在独立Rayleigh衰落信道下,与不采用星座成形的系统相比,该方案大大提高了系统的误差性能和成形增益。     

变发散角半导体激光器光束整形发射系统设计

变发散角半导体激光束具有重要的应用意义.根据光线传输的基本原理,从理论上推导了变发散角半导体激光器光束整形发射系统的设计公式,在推导过程中,为了更准确地设计系统,保证出射光束质量,需考虑半导体激光器的固有像散.讨论了最佳的系统结构形式,推导了半导体激光器光束整形的变发散角公式,根据该公式设计了一个变发散角半导体激光器光...