燃气舵装置性能参数测试和分析

燃气舵装置性能参数的准确获得对导弹飞行控制性能设计非常重要。论述了燃气舵装置需要测试的性能参数、卧式六分力测试系统和燃气舵五分量天平测力系统的测试原理,介绍了两系统测试燃气舵性能参数的实现方法,分析了两系统影响测试精度的因素和优缺点,通过试验数据比较,指出了适合测试燃气舵各性能参数的试验方法。文中总结的测试和分析方法是合理、可行的。     

点火状态对固体火箭燃气流动影响的实验研究

结合固体火箭燃气射流的特点,开发了基于皮托管技术的多点压力参数实验测量装置,运用实验的方法,对燃气射流流场进行了研究.针对不同的发动机点火状态,在射流轴线的不同距离上对一系列测点位置的总压参数进行了测量.研究证明该试验测试装置对燃气射流流场的测试是适宜的,实验数据分析表明高低温点火状态对固体火箭燃气流场具有一定的影响作用,所得结论对固体火箭武器研究具有指导意义.     

气体发生剂高压燃气驱动液体高速喷雾的试验研究

介绍一种气体发生剂高压燃气驱动的高速液体喷洒装置,利用高速摄影和压力测试系统,研究了安装螺旋喷嘴的喷洒装置在不同装药量下的喷射初始速度和液体雾化射流的扩展过程。实验结果表明,气体发生剂装药量大于50 g时,喷洒装置可快速形成稳定的喷雾锥,随着药量的加大,喷嘴的雾化效果也显著提高。并发现气/液界面的Rayleigh-Taylor(RT)不稳定性会对喷嘴的正常工作带来不良影响。     

火炸药燃气中毒性气体评价研究

使用密闭爆发器模拟火炸药产品实际燃烧过程,并采用红外光谱法对燃气成分中的毒性气体进行检测.分别测试不同火炸药的燃气成分,对特定油田用火炸药燃气中产生HCN的机理进行分析,并提出抑制燃烧过程中产生HCN的措施.研究结果表明:发射药配方中添加KNO3、CuO、聚酯均能降低发射药燃气中CO的含量.     

定向反射膨胀装置作用特性研究

为实现冲击波尽量小的高效后坐,提出了定向反射膨胀原理,设计了相应的装置。运用一维准定常气体动力学理论,建立了气体动力学模型,根据实际情况选定模型参数进行数值分析,得到了装置减后坐效率及弹丸炮口初速等理论分析结果; 根据理论分析结果确定了实验装置的基本参数,设计实验并在某30 mm口径的火炮上进行定向反射膨胀装置的实验验证。实验测试结果表明,理论分析结果与实验测试结果基本一致,验证了定向反射膨胀装置作用特性研究的正确性,为定向反射膨胀原理及装置的继续研究打下了基础。     

流量调节装置燃气通道CFD仿真计算

为设计出流量调节装置最佳燃气通道型面,文中在简要介绍N-S方程主要算法的基础上,利用Fluent软件对燃气通道进行了CFD仿真计算,通过模拟燃气通道内的流体运动,分析了不同扩张角度对内流场的影响,获得了燃气粒子对通道的理论冲刷情况,计算结果表明带最佳扩张角的燃气通道方案能有效降低气流的出口速度,试验结果与仿真结果基本一致.     

含钾盐添加剂的火药燃烧产物导电特性研究

为提高火药燃烧产物的导电特性,基于气体热电离理论,在火药中添加电离电位较低的碳酸钾碱金属化合物以提高其电离度。通过对火药燃烧反应的化学物理过程进行分析,结合内弹道理论和等离子体理论建立火药燃气的热电离模型,数值计算了火药燃烧过程的压力、燃气温度等热力学变化过程。应用Saha方程和交错法,分析了火药力、燃烧室容积和钾盐含量变化对燃烧产物电子密度和电导率的影响规律,并采用光谱测量法试验测试了无钾盐添加剂和加入钾盐后火药燃烧产物的发射光谱强度。研究结果表明：添加电离种子碳酸钾后能够使火药燃气具有较高的导电性;火药力和药室容积的增加可以相应地提高燃气电导率。     

气体发生剂

在火箭导弹、航天飞行器以及民用装置中常常需要压缩气体作辅助能源或充气装置的气源。这导致气体发生剂的发展。可以采用压缩空气,液体燃料等作为气体发生剂。随着固体火箭推进剂的发展,促进了用固体推进剂作为燃气发生剂的研制。固体燃料气体发生器较之其它气体发生剂具有更多的优点,如体积小,重量轻,气体生成率高,气体无毒和腐蚀性小,使用方便,维修简便。因此,得到广泛地应用,例如:     

定容燃烧器法热损失率不确定度分析

定容燃烧器法是一种测试高压下固体推进剂燃速特性的方法。定容燃烧器法工作过程中散热损失是影响燃速测试精度的主要因素。推导了热损失率计算方程,分析了各因素对热损失率的影响;建立了热损失率测试结果的不确定度评定方法,并对测试结果进行了不确定度评定。研究表明,推进剂试样燃面、燃气定容比热、燃气压强、燃气温度是影响热损失率不确定度的主要因素,其中燃面是影响热损失率不确定度的最大因素;后续实验中必须提高推进剂试样尺寸加工精度,减小推进剂试样燃面误差。     

固体火箭发动机燃气导流片导转特性分析研究

在固体火箭发动机喷管内采用燃气导流片技术,可以使火箭绕其纵轴旋转。文中建立了喷管内燃气导流片流场数值分析的数学和物理模型,通过数值仿真分析了导流片产生导转力矩的原因及其结构参数对火箭导转特性的影响,并采用高速旋转试验和外弹道飞行测试试验结果与理论计算结果进行比较,结果表明火箭最大转速的理论计算结果和试验结果一致性较好,从而验证了燃气导流片数值模型的可靠性。     

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.     

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.     

Design and Analysis of Test Schemes of Static Postponing Time on Shrapnels Used to Riot Control

The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and three kinds of pressures,the consumed ammunitions are more excessive. Statistic analysis and tentative checkout about a lot of test data are done,feasibility gists are put forward for optimizing of the test design scheme. The optimizing design and data analysis of test scheme of the item are done by managing uniformity design theory, two scientific and reasonable six-point test schemes are confirmed. The feasibility and reliability of the optimizing design schemes put forward above are proved ulteriorly by test validating. The gained schemes not only have good design uniformity and little ammunition wastage and meet the test demand, but also have better forecast ability for the result data of other points using the mathematic models from the actual test points.     

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.     

Design of Non-fragile Satisfactory Estimator for Linear Continuous Perturbed Stochastic Systems

The design problem of non-fragile estimator is addressed for a class of perturbed linear continuous systems. The perturbations occur on the plant and estimator parameters. The estimator designed should force the error system to achieve the desired decay rate and force the steady error variance less than the specified upper bound irrdevancy of the admissible plant perturbations and estimator perturbations. Consistency problem of the decay rate with the variance upper bound is first considered via linear matrix inequality （LMI） approach. The solution of the estimator parameter under specifications to be consistent is then discussed. The consistency condition of specifications and estimator parameter solution are transformed to feasible or minimum problems subject to a set of LMI respectively. The method is illustrated by a numerical example.     

An Improved Scene-based Nonuniformity Correction Algorithm for Infrared Focal Plane Arrays Using Neural Networks

The improved scene-based adaptive nonuniformity correction （NUC） algorithms using a neural network （NNT） approach for infrared image sequences are presented and analyzed. The retlna-like neural networks using steepest descent model was the first proposed infrared focal plane arrays （IRFPA） nonuniformity compensation method, which can perform parameter estimation of the sensors over time on a frame by frame basis. To increase the strength and the robustness of the NNT algorithm and to avoid the presence of ghosting artifacts, some optimization techniques, including momentum term, regularization factor and adaptive learning rate, were executed in the parameter learning process. In this paper, the local median filtering result of Xij （ n ） is proposed as an alternative value of desired network output of neuron Xij （ n ）, denoted as Tij （ n ）, which is the local spatial average of Xij （ n ） in traditional NNT methods. Noticeably, the NUC algorithm is inter-frame adaptive in nature and does not rely on any statistical assumptions on the scene data in the image sequence. Applications of this algorithm to the simulated video sequences and real infrared data taken with PV320 show that the correction results of image sequence are better than that of using original NNT approach, especially for the short-time image sequences （several hundred frames） subjected to the dense impulse noises with a number of dead or saturated pixels.     

Piecewise Filter of Infrared Image Based on Moment Theory

The disadvantages of IR images mostly include high noise, blurry edge and so on. The characteristics make the existent smoothing methods ineffective in preserving edge, To solve this problem, a piecewise moment filter （PMF） is put forward. By using moment and piecewise linear theory, the filter can preserve edge. Based on the statistical model of random noise, a related-coefficient method is presented to estimate the variance of noise. The edge region and model are then detected by the estimated variance. The expectation of first-order derivatives is used in getting the reliable offset of edge. At last, a fast moment filter of double-stair edge model is used to gain the piecewise smoothing results and reduce the calculation. The experimental result shows that the new method has a better capability than other methods in suppressing noise and preserving edge.     

Bistatic Sonar Localization Based on Best Linear Unbiased Estimation

A best linear unbiased estimation （BLUE） algorithm for bistatic sonar localization is proposed. The Cramer-Rao bound for bistatic Sonar and the geometrical dilution of precision （GDOP） in different conditions are given. The simulation results show that the location accuracy of BLUE algorithm is higher than the weighted least square method.     

Research on Gear-broken Fault Diagnosis in a Tank Gearbox

A fault diagnosis method of working position gear in a tank gearbox is put forward based on simulating the fault of working position gear in an actual tank, extracting the envelope of vibration signal by Hilbert transformation amplitude demodulation method, and zooming the low-frequency band to envelope signal.