伞形端头光源-光纤耦合器

大功率、高能量、窄脉冲激光与光纤之间的耦合对激光的应用有着重要的作用.但是,由于光纤端面具有一定的损伤阈值,利用透镜实现上述耦合是十分困难的.本文通过分析光纤端面的损伤机理,设计了一种伞形端头光源-光纤耦合器,实现了大功率(10MW),高能量(20mJ),窄脉冲(20ns),高频电光调Q Nd∶YAG激光与光纤之间的耦合,耦合效率达到80%以上.     

一种短波宽带定向耦合器的设计

根据变压器串并联同时耦合的原理，提出了一种利用三线变压器魔T和传输线变压器构成定向耦合器的方法，给出了设计原理，设计制作了一种短波宽频带、大功率定向耦合器。并对其参数进行了理论计算和实际测量，测试结果与理论分析吻合，满足设计要求。经过实际应用，验证了设计方法的可行性。     

激光驱动飞片系统结构及参数设计

激光驱动飞片是一种获得动高压的新兴技术。激光与飞片的能量耦合效率、飞片的平整性是影响激光驱动飞片性能的关键因素,而激光参数、飞片结构及参数是能量耦合和飞片平整性的主要影响因素。分析了激光驱动飞片的原理,激光驱动飞片的结构和参数设计,提出了进一步研究所面临的问题。     

激光化学微推进推力性能的实验研究

影响激光化学微推进推力性能的主要因素为激光和推进工质的参数。对不同厚度的自研制双基药复合工质进行了推力性能的实验研究。实验中,激光焦斑为50 μm,激光功率密度为4.74×10⁴ W/cm². 实验发现随着工质厚度的增加,工质的冲量耦合系数有渐增的趋势,而比冲有渐减的趋势。将激光功率提高近1倍,选用功率为1.80 W的半导体激光器,25 μm厚的双基药复合工质的冲量耦合系数和比冲分别达到了130.8 dyne/W和493.0 s,此时,名义上的激光能量利用率高达316.4%,是聚氯乙烯（PVC）工质的6.46倍,化学能的释放更加充分。     

皮秒激光对电荷耦合器件多脉冲损伤效应研究

为了研究短脉冲激光对光电系统的作用机理,开展了高重频皮秒激光对行间转移Wat-902B型电荷耦合器件（CCD）的损伤实验研究,并对损伤机理进行了分析。调整皮秒激光指向相机光学系统入瞳位置,并使用电动转台方法控制激光与光学系统的交汇时间,从而控制到达光电探测器的脉冲个数。采用激光传输的二阶矩理论获得了激光到达CCD靶面的光斑能量分布,光斑测试精度优于20.3%. 考虑到实验误差,1.5 ns、400 ps千赫兹高重频激光条件下,转台转速201°/s,器件功能性损伤阈值为13.6~121.0 mJ/cm²,显著小于单脉冲损伤阈值263~1 146 mJ/cm². 单脉冲器件功能性失效机理为垂直转移电路电极间短路,多脉冲激光条件下的器件功能性失效机理与单脉冲损伤显著不同,表现为多线损伤的积累过程。     

单模光纤定向耦合器

对于具有信息容量大及单模干涉优点的单模光纤通讯和各种光纤传感器来说,都必须采用高效率的耦合器,为了降低连接损耗,提高耦合功率,Sheem和Giallorenzi共同研究出一种腐蚀——研磨技术,采用这项技术可以保证耦合器中的两块石英块(包括光纤芯)之间的严密接触,用这种方法制造的光纤耦合器具有连续可调、传输损耗低,不受偏振影响及高导向性等优点。可作为串联系统中可调的发送/接收耦合器及并联系统中的功率分束器及光纤     

激光多点均匀点传火技术实验研究

使用大功率Ｎｄ：ＹＡＧ激光器产生激光,通过光学玻璃窗和光纤能量传到金属点火器中点燃点火药,从而达到在点火管内实现多点同时点火的作用。实验用激光成功的点燃了点火药,并且把激光单点点火,不同直径光纤多点激光点火实验结果与普通的电点火实验结果进行了比较,发现使用激光确定能实现多点同时点火达到     

S波段宽带定向耦合器的设计

介绍了宽带高方向性S波段10 dB定向耦合器的设计方法,并采用平行线直接耦合器结构设计了(2~3)GHz定向耦合器,设计的耦合器通带内直通传输系数为(-0.58~-0.69)dB,耦合系数为(9.27~9.57)dB,隔离端口隔离度大于等于20 dB。     

高功率半导体激光器光纤耦合线阵技术

研究高功率半导体激光器的光纤耦合和光纤输出端密排成线阵的技术。论述了微柱面透镜对高功率半导体激光器椭圆光束的准直原理,计算了剩余发散角,设计了光纤耦合器件和光纤输出端密排成线阵的夹具。这种方法耦合效率高,线阵中各激光元地址可设定,并可对各激光元输出功率进行调制。它作为能量型器件,可在激光显示技术(LDT)和选择性激光烧结快速成型(SLS RP)技术中应用。     

相控阵大功率T/R模块关键技术分析

本文介绍了大功率T/R模块的功能和原理。针对大功率T/R模块自身的特点,结合工程经验,详细分析了在设计和应用中功放调制电路设计、功放芯片残余能量释放、接收支路设计和储能电容计算等关键技术。     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Expert Systems Aimed at General Design of Projectiles

Expert systems aimed at the general design of projectiles can implement a series of intelligent designs, such as the design of HE shell, the scheme expounded and proved, the emulation analysis and calculation, etc. Aiming at the product design feature, the expert system adopts the object-oriented knowledge representation and all kinds of inference control engines to describe and reason the relevant knowledge regarding the product through the microcomputer. It embodies the foundation of emulation analysis and simulated manufacturing of the shell. It makes use of the method that knowledge expression is combined with condition of inference to carry out the overall design and emulation and reference.The paper gives the ways through which the functions can be achieved, gives the modularization of reference and the design methods of systematization, puts forward the method of knowledge expression and working interface, and supplies a platform for similar products of the shell category that can be quickly designed.     

Parameter Identification for the Valve Control Cylinder System of a Hydraulic Manipulator

In mechanical, hydraulic and electronic systems, the determination of system parameters is often challenging because liquid parameters often change significantly, due to variations in working and environmental conditions. Therefore, it is of significant practical importance to identify those parameters through experimental procedures. A systematic approach to identifying parameters in the valve controlling cylinder system of hydraulic manipulators is provided. It first derives the transfer function of the system, and then uses P control of PID control to predict system parameters. The predicted parameters are further validated using PID control. The prediction through simulation using MatLab language is utilized, which agrees well with experimental results.     

Three-dimensional Numerical Simulation of Combustion Field in the Combustion Chamber

In order to study the effect of rotation on the combustion in the underwater vehicle, a two-phase turbulent combustion process is described with Reynolds stress turbulence model, eddy-dissipation turbulent combustion model, P-1 radiation model and particle tracking model of liquid. The flow in the rotating combustion chamber is simulated at two different working speeds, 0 r/min and 1 000 r/min by Fluent software. The temperature, gas velocity, static pressure of wall and fuel concentration are computed and compared. The results show that the combustion in rotating combustor is faster and more effective.     

Software Communication Architecture Implementation and Its Waveform Application

This paper attempts to do a research on the development of software defined radio（SDR） based on software communication architecture（SCA）. Firstly, SCA is studied and a whole reference model of SCA3.0 core framework （CF） is realized; Secondly, an application-specific FM3TR waveform is implemented on the platform of common software based on the reference model; Thirdly, from the point of view of real-time performance and software reuse, tests and validations are made on the above realized CF reference model and FM3TR waveform. As a result, the SCA-compliant SDR has favorable interoperability and software portability and can satisfy the real-time performance requirements which are not too rigorous.     

Dynamic Simulation of the Tank Gun Recoil Response

By using the ATV module of MSC. ADAMS, the dynamic simulation of recoil response of tank gun is analyzed.How the recoil force affects the bodywork and the suspension during gun firing, as well as the changing status of the gun muzzle‘s velocity are gained. All results and analyzing methods are offered for the designing basis of optimizing tank vehicle-gun match. The constructive exploration is beneficial to improving the general capability of tank.     

Survey of Controllable Suspension System for Off-road Vehicles

The controllable suspension system can improve the performances of off-road vehicles both on road and cross-country. So far, four controllable suspensions, that is, body height control, active, semi-active and slow-active suspensions, have been developed. For off-road vehicles, the slow-active suspension and the semi-active suspension which have controllable stiffness, damping and body height are more appropriate to use. For many years, some control methodologies for controllable suspension systems have been developed along with the development of modern control theory, and two or more original control methods are integrated as a new control method. Today, for military or civilian off-road vehicles, the R&D of controllable suspension systems is ongoing.     

Passive Acoustic Radar for Detecting Supersonic Cruise Missile

A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the ““acoustic fingerprint““ character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model, the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.     

Super-resolution Restoration of Remote-sensing Images

A novel image restoration scheme, which is super-resolution image restoration algorithm Poisson-maximum-afterword-probability based on Markvo constraint （MPMAP） combined with evaluating image detail parameter D, has been proposed. The advantage of super-resolution algorithm MPMAP incorporated with parameter D lies in the fact that superresolution algorithm MPMAP model is discrete, which is in accordance with remote-sensing imaging model, and the algorithm MPMAP is proved applicable to linear and non-linear imaging models with a unique solution when noise is not severe. According to simulation experiments for practical images, super-resolution algorithm MPMAP can retain image details better than most of traditional restoration methods; at the same time, the proposed parameter D can help to identify real point spread function （PSF） value of degradation process. Processing result of practical remote-sensing images by MPMAP combined with parameter D are given, it illustrates that MPMAP restoration scheme combined PSF estimation has a better restoration result than that of Photoshop processing, based on the same original images. It is proved that the proposed scheme is helpful to offset the lack of resolution of the original remote-sensing images and has its extensive application foreground.     

Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.