无线电引信双源辐照效应研究

为了探索复杂电磁环境对无线电引信的作用规律,提出双辐射源电磁环境构建方法和试验方法,试验研究了无线电引信的双辐射源电磁环境效应,找到了使无线电引信意外起爆的双辐射源辐照频率组合方式和敏感阈值。发现双辐射源使无线电引信意外起爆的作用机理:引信天线及弹体接收到差频为多普勒频率的复合连续波信号,经自差机振荡器混频、检波管检波并滤波后,输出信号幅度较大的正弦波信号,经低频电路放大、信号整流积分及抗干扰惯性支路的共同作用,通过增幅速率选择电路,触发执行级电路误动作导致引信意外起爆。     

基于FPGA的海底泥浆举升泵控制系统设计与实现

目前,采用先进控制理论和先进控制器控制海底泥浆举升泵作为深水双梯度钻井的关键技术之一,是成功进行井控的关键;提出了针对双梯度钻井系统中海底泥浆举升泵的控制方案,选择FPGA作为系统控制器,给出了控制系统硬件构成,基于VHDL语言编制程序,分别实现对A/D、D/A的时序控制;根据海底泥浆举升泵控制系统特点,基于FPGA设计完成模糊PI控制算法,并将基于FPGA的模糊PI算法应用于对举升泵的控制,试验结果表明,设计的控制系统实现了海底泥浆举升泵入口压力为恒定值的控制要求;模糊PI控制器对系统具有较好的控制性能,为双梯度钻井作业提供了指导。     

HNS—IV为基的PBX配方性能

按照美军标《引信安全设计准则》MIL-STD-1316E的规定，HNs是直列式爆炸序列许用传爆药。从国外公开文献可以看出只有高纯度、高比表面积的HNS—IV作为起爆装药正式应用于武器的起爆序列。但单质的HNS—IV炸药由于成型性能较差，不能直接装药，文中开展了HNS—IV为基的PBX配方设计，对其性能进行了表征。     

基于LabVIEW激光引信回波模拟装置设计

激光引信回波模拟装置是激光引信测试设备的重要组成部分。介绍了激光引信回波模拟装置的组成,设计了用于该装置的硬件电路和软件控制系统。硬件电路采用单片机完成控制指令的接收和控制信号的产生,使用串行扩展芯片GM8125将单片机AT89S52的串行口扩展成5个,满足了激光引信回波模拟装置串口资源要求。软件控制系统基于LabVlFⅣ设计,主要包括串口通信程序和控制指令的产生程序,控制指令经串口通信传送给硬件电路。实验结果表明,该装置满足激光引信测试设备的要求。     

无刷直流电动机矢量控制系统的研究

针对方波驱动的无刷直流电动机有输出转矩脉动较大的问题,根据无刷直流电动机非线性、多变量、强耦合的特点,建立了以id=0为控制策略的无刷直流电动机矢量控制系统。把传统PI控制与模糊控制相结合,对速度环设计了一种模糊PI控制器, 利用模糊控制对PI控制器参数进行自整定。利用MATLAB/Simulink搭建了无刷直流电动机矢量控制系统仿真模型,分别对传统PI控制器和模糊PI控制器作用下的矢量控制系统进行仿真研究。仿真结果表明模糊PI控制器性能的优越性,提高了控制系统的动态性能和静态精度。以SH79F1611为控制核心,搭建了无刷直流电动机矢量控制系统的硬件实验平台,实验结果验证了控制方案的可行性。     

激光引信探测技术研究

分析了激光引信探测技术发展状况及工作原理。针对目前在研的激光引信探测的关键问题,即激光引信的前倾探测和伪随机码探测技术进行了分析。得出两个结论:激光引信对目标的45°前倾探测获得了一定的探测提前量,更有利于识别目标,也可以获得最佳起爆参数;伪随机码体制激光引信探测技术在保密性和抗有源干扰性能等方面比普通脉冲体制激光引信都有本质的提高。     

定向起爆部脉冲激光方位探测引信系统时间空间匹配特性

根据定向起爆部对引信提出的时间匹配和空间匹配的要求,针对弹目交会相对运动环境,在惯性坐标系下3个相互垂直的2维平面内,建立了弹目相对速度下脉冲激光方位探测引信系统的最佳起爆延时和最佳起爆方位角模型,并对相关时间匹配和空间匹配特性进行了量化及数值仿真分析。结果表明:模型与弹目交会角、目标初始方位角、发射激光束与弹丸速度夹角、引信中心至目标尾部距离、目标外型参数、目标速度、破片飞散速度、弹丸内部结构参数、弹丸速度等目标区环境信息有关     

基于PWM整流器双闭环控制的超导电磁储能功率调节器的研究

本文基于电压型超导电磁储能系统(Superconducting Magnet Energy Storage,简称SMES)的基本结构和工作原理,结合脉冲宽度调制(Pulse Width Modulation,简称PWM)整流器的应用,建立了三相电压型PWM整流器控制的超导电磁储能系统的数学模型.设计了具有前馈解耦控制的PWM整流器双闭环控制系统,并运用Mat-lab/Simulink仿真分析软件对基于PWM整流器的超导电磁储能双闭环控制系统进行了仿真研究.仿真结果表明PWM整流器双闭环控制策略应用于SMES电压型SMES功率控制器比直接电流控制等传统的控制策略反应速度更快,向电网注入谐波电流更小,有利于提高了电网的稳定性.     

多旋翼无人机位置控制系统设计

摘要：为解决小型无人机位置控制系统成本高、控制精度低以及控制性能不稳定等缺点,以自主研发的多旋翼无人植保机作为研究对象来设计位置控制器。设计过程中,飞行器的位置建模误差,模型参数变化、GPS定位精度以及外部扰动（如风速）成为有待解决的难题。为解决上述问题,首先设计了卡尔曼滤波器对反馈所得速度和位置信息进行滤波,并采用参考模型滑模控制理论（Model Reference Sliding Mode Control,MRSMC）设计位置控制器,提高控制系统的鲁棒性。为了验证位置控制器的性能,进行了户外飞行实验,实验结果表明,无论是在悬停还是目标点追踪情况下,所设计控制系统都具有良好的跟踪性与鲁棒性     

针对调频引信的窄带扫频式干扰优化方法

扫频式干扰是调频体制引信的主要威胁之一,但其干扰效果具有一定随机性。为了提高其干扰效率,在理论分析扫频式干扰作用下调频引信失效机理的基础上,提出了一种针对单通道调频多普勒引信的窄带扫频式干扰优化方法,可以获取最优的扫频频率步进点数,并依此进行非等间隔频率步进的窄带扫频式干扰。仿真与实测结果表明,该方法可以提高扫频式干扰的干扰效率,同时该方法也可以为成功干扰采用多通道等抗干扰措施的调频引信提供理论设计依据。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.