装填参数对大口径中心爆管式子弹抛撒速度影响

为研究大口径子母弹的抛撒机理,探讨了中心爆管式子母弹抛撒的几何模型;根据其结构特点,提出了燃气做功时子弹推力面积修正系数的计算方法,建立了内弹道抛撒模型并进行数值仿真,获得燃气压力、子弹速度和子弹加速度等内弹道性能曲线,采用正交试验法分析了抛撒药装药量、中心管炸裂压力及中心管药室容积对子弹抛撒速度的影响,结果表明中心管炸裂压力是最敏感的的影响因素,为中心爆管式大口径子母弹抛撒机构设计提供了依据。     

子母弹内燃式气囊抛撒模型及计算机仿真

子母弹内燃式气囊子弹抛撒系统是一种具有广泛应用前景的抛撒技术,它包括了抛撒药燃烧,燃气囊充气和各子弹运动的变化过程,本文描述了子母弹内燃式气囊子弹的抛撒过程,建立了弹抛撒过程的数学模型,并给出了地面仿真试验和计算机仿真结果。     

中心爆管子母弹抛撒内弹道过程的数值模拟

为得到中心爆管子母弹准确的抛撒结果,对子弹进行了动力学分析,将抛撒分为4个时期,结合经典内弹道理论,建立了完整的内弹道模型.利用此模型对某型火箭弹中心爆管子母弹战斗部的抛撤内弹道过程进行了模拟计算.结果表明,抛撒后外圈子弹的过载略低于内圈子弹,其子弹速度略高于内圈子弹.这与试验结果也十分接近.所建立的模型可以较为准确地描述抛撒内弹道的全过程.     

子母弹中心燃气式抛撒定容阶段试验及仿真

为研究子母弹中心燃气式抛撒过程中推弹装置在由定容向变容阶段转换瞬间的受力状态对子弹最终抛速和姿态的影响,设计了中心燃气式抛撒定容阶段试验装置;建立了燃气发生器内的零维火药燃烧模型和推弹装置内定容流场的二维两相流模型。数值仿真结果与试验结果的对比分析验证了模型的可行性;分析了不同的燃气发生器小孔分布和几种扰流装置对推弹装置受力状态的影响,结果表明：改变小孔分布使边界所受合力矩呈振幅衰减的周期性振荡,造成子弹抛撒姿态的不确定性;不同类型、不同大小和位置的扰流机构对抛撒性能有重要影响。     

子母弹燃气囊静态抛撒气囊破裂射流流场仿真分析

针对子母弹燃气囊抛撒试验中出现的气囊破裂对子弹运动特性的影响,建立了气囊抛弹的三维动力学模型。基于计算流体力学Fluent软件,通过编译自定义程序将六自由度刚体动力学方程与流体控制方程进行耦合,对气囊破裂自由射流流场结构特性及子母弹抛撒过程中气囊破裂射流流场结构特性进行对比,获得了气囊内压力变化规律。对不同破口位置的气囊射流流场进行仿真分析,获得了不同破口位置气囊内压力变化规律及对子弹的运动特性影响。计算结果表明:与气囊破裂自由流场结构相比,存在子弹时对气囊破裂射流流场结构有很大的影响;在中心位置破裂时对气囊内压力变化影响最大,破口在中心位置及短边侧时对子弹姿态的影响最大。该研究结果对预估子弹飞行弹道,了解气囊破射流流场对子弹运动的作用机理和影响规律,提高子母弹分离时的可靠性和安全性具有参考价值。     

子母弹内燃式气囊抛撒内弹道建模及数值仿真

为研究子母弹内燃式气囊抛撒的内弹道过程, 探讨了内燃式气囊抛撒系统的结构和工作原理;根据内燃式气囊膨胀过程的特点,提出了气囊容积和有效推力面积的计算方法,建立了内燃式抛撒机构的抛撒内弹道模型.利用数值计算方法,获得了燃气压力、子弹速度和子弹加速度等内弹道性能曲线,并对计算结果进行了分析.数值仿真及地面试验结果验证了模型的合理性,为子母弹内燃式抛撒系统结构设计提供了理论研究方法.     

子母弹抛撒技术综述

子母弹是以均匀散布的子弹覆盖目标，提高有效的杀伤范围的一类武器。子母弹的战术技术要求决定了子弹在目标区上空要呈现均匀的散布状态，而能否达到要求的散布就离不开抛撒技术。子母弹抛撒技术十分复杂，它涉及到许多问题，本文介绍了子母弹抛撒一些主要方法，对燃气推动式抛撒进行了重点介绍，并对我军子母弹抛撒技术的发展提出了一些建议。     

瓦片抛撒式子母弹子弹落点散布影响因素分析

针对子母弹已有开舱抛撒方式落区中心形成较大盲区的问题,提出了一种"瓦片式"抛撒机构.这种机构作用可靠性高.结构简单,且成本较低,加工方便.仿真计算结果表明,采用瓦片式抛撒机构的子母弹子弹散布呈星形,落点减少了中间盲区,抛撒高度和抛撤速度越低,盲区越小,适合于攻击轻型装甲目标.     

中心炸管内调速挡板对子弹抛撒速度影响的研究

基于ANSYS/LS-DYNA非线性动力有限元方法对内置调速挡板型中心炸管式子母弹的抛撒进行数值模拟分析是高效的。为了研究调速挡板对各方向上的子弹抛撒速度及其载荷分布的影响,基于某航空子母弹模型,将挡板的覆盖区域作为研究对象,设置了3种不同工况。数值模拟结果表明,在中心管内设置挡板会对子弹抛撒速度产生显著的影响,且子弹抛撒速度与挡板覆盖的方向有关,各方向子弹抛撒速度的分布范围在17～37 m/s之间。其中在未设置挡板的方向上子弹抛撒速度最大,在35 m/s左右。数值模拟结果对差异化目标打击类型子母弹的子弹散布规律研究有一定参考价值。     

波纹管式抛撒动力学模型及影响因素研究

针对波纹管式抛撒,基于经典内弹道理论和典型双层子弹排布波纹管结构关系式,建立了抛撒过程的动力学模型。用四阶龙格-库塔方法编写了数值计算程序,对某典型的子弹排布方式进行了内弹道性能计算,获得了抛撒过程中药管压力、波纹管内压力、内外层子弹速度、加速度、火药燃烧百分数随时间的变化曲线。在此基础上,计算分析了药量和波纹管周长等因素对抛撒过程的影响,获得了压力、子弹速度、加速度随上述因素的变化规律。计算结果符合实际变化规律,对子母战斗部波纹管式抛撒机构设计具有借鉴和指导意义。     

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.