微纳米HMX基PBX力学、导热性能及药片撞击感度

为了研究微纳米尺度下颗粒尺寸对于炸药撞击感度的影响规律及作用机制,将三种奥克托今(HMX,粒径为100~300 nm,1~2μm,10~20μm)基高聚物粘接炸药(PBX)造型粉压制成表观密度分别为1.74 g·cm~(-3)与1.50 g·cm~(-3)的PBX样品,研究了HMX粒径与表观密度对PBX样品压缩力学性能、导热性能以及药片撞击感度的影响。使用扫描电镜观察了样品受落锤撞击前后的微观形貌,并通过自行设计的试验装置测试了落锤撞击加载过程中样品的受力情况。结果表明,PBX样品的压缩强度、压缩模量、导热系数及热扩散系数均随HMX粒径的减小而显著增大。在相同表观密度下,PBX样品的撞击感度随HMX粒径减小而明显降低;对于含同种粒径HMX的PBX样品,撞击感度随表观密度的增加而略微升高。撞击作用下HMX粒径较大的样品主要发生孔穴压缩与颗粒破碎,HMX粒径较小的样品主要发生颗粒层的剪切滑移。在相同撞击条件下,作用于试样力的峰值随表观密度的增大或粒径的减小而增大。认为炸药颗粒细化所带来的撞击感度降低是细化后炸药内部孔隙尺寸减小、孔隙结构均匀化程度提高以及导热性能提升等因素共同作用的结果。     

PBX炸药及其模拟材料冲击损伤的试验研究

文中利用轻气炮驱动飞片加载技术对JO-9159炸药及其模拟材料样品进行了冲击加载，使其产生损伤，利用锰铜压阻计测量了试件的冲击压力。通过扫描电镜（SEM）对回收样品进行了显微观察．分析比较了炸药和模拟材料在冲击载荷作用下的损伤破坏模式。结果表明两者都具有脆性材料的损伤破坏特征，相对于PBX炸药模拟材料具有更明显的脆性特征。在细观上，PBX和模拟材料的损伤破坏模式是以微裂纹为主的脆性损伤，模拟材料的破坏主要表现为造型粉颗粒的破裂、破碎形成裂纹，而PBX炸药主要表现为颗粒之间的脱粘，并伴有颗粒的破碎。     

低温下叠氮聚醚推进剂冲击损伤特性与动态力学性能

利用仪器化落锤冲击试验机在-40℃下对叠氮聚醚推进剂进行了冲击加载模拟实验,通过X射线微层析成像技术(X-μCT)表征了推进剂的冲击损伤特性,并采用动态力学分析研究了叠氮聚醚推进剂在不同加载频率下的动态力学性能。结果表明,叠氮聚醚推进剂动态力学参数表现出显著的加载频率依赖性,当加载频率由1 Hz增大至20 Hz时,其玻璃化转变温度由-38.1℃升高至-23.1℃;相应测试条件下,推进剂试样在冲击加载能量不低于2 J时发生断裂,未冲断推进剂无宏观裂纹产生,但其内高氯酸铵(AP)颗粒已部分破碎;被冲断试样冲击曲线中包含不稳定裂纹扩展过程,表明叠氮聚醚推进剂在低温下具有一定的脆性材料特征,推测其损伤模式为含缺陷的AP颗粒首先发生穿晶断裂,初始微裂纹扩展于基体中并相互贯通扩大,最终导致试样断裂。     

奥克托今/黑索今颗粒炸药在落锤撞击下碎片分布的实验分析

在落锤撞击过程中,奥克托今/黑索今(HMX/RDX)大颗粒的碎片大小和分布是影响热点形成以及燃烧速率的一个重要原因,因此对落锤撞击下碎片大小及其分布的分析是研究落锤撞击下热点形成的一个必要前提。用落锤撞击装置对HMX/RDX大颗粒进行破碎实验分析。运用Mastersizer 2000激光粒度分析仪对破碎后的HMX/RDX碎片样品进行粒度分析,得到了HMX/RDX在不同落锤高度下碎片的分布曲线和碎片平均尺寸。从实验结果发现,随着落锤高度的增加,碎片的尺寸不断减小,但减小的幅值在变小。另外,在同样的落高下,HMX大颗粒的碎片比RDX大颗粒的碎片尺寸大。     

低压长脉冲作用下PBX炸药的响应特性

为研究塑料粘接炸药(PBX炸药)在低压长脉冲作用下的响应特性,采用大落锤试验的方法对壳体约束下的炸药样品进行低速撞击加载; 采用薄膜式PVDF对炸药试样顶部和底部的压力-时间曲线进行测量,通过壳体外表面的应变片测试壳体的环向和轴向应变,同时采用高速相机捕捉炸药在撞击作用下的反应发光现象; 采用LS-DYNA非线性有限元软件开展数值模拟,研究大落锤冲击载荷作用下PBX炸药的动态响应特性。结果表明,落锤撞击速度为3 m/s时,炸药受撞击面的峰值压力约为100 MPa,炸药不发生反应; 落锤撞击速度为5 m/s时,炸药受撞击面的峰值压力为200 MPa,炸药发生明显的化学反应; 有限元计算结果与试验测试结果具有较高的吻合度,可以很好地模拟炸药在低压长脉冲冲击下的力学响应特性。     

某RDX基含Al炸药发射安全性

用400 kg大型落锤实验和一级轻气炮实验研究了某RDX基含Al炸药(R-Al炸药)的发射安全性,获得了炸药装药在两种实验条件下的应力-时间曲线。进行了R-Al炸药与铸装B炸药发射安全性的比较。结果表明:R-Al炸药在大型落锤加载应力1.47 GPa、加载时间3.04 ms及一级轻气炮加载应力660 MPa、加载时间41μs条件下未发生点火;铸装B炸药在大型落锤加载应力840 MPa,加载时间2.10 ms及一级轻气炮加载应力394 MPa、加载时间40μs条件下发生点火,显示R-Al炸药的发射安全性优于铸装B炸药。     

两种典型炸药装药的撞击试验研究

通过小落锤对JO-8和B炸药装药进行撞击加载,并对撞击过程和试验后样品分别进行了高速摄影和扫描电镜分析。撞击试验发现JO-8炸药比B炸药具有更高的抗撞击能力;高速摄影发现两种炸药装药均经历冲击、塑性流动、飞散、反应等过程,装药的反应发生在装药损伤后;扫描电镜表明B炸药在低速撞击下的损伤模式以界面脱粘、沿晶断裂为主,JO-8炸药装药则以剪切变形和穿晶断裂为主。上述研究表明:粘结剂能够改善炸药装药的抗撞击能力,炸药装药工艺决定了炸药在撞击加载下的损伤模式。     

RDX晶体特性对冲击感度的影响规律

采用标准隔板和落锤撞击试验方法分别研究了RDX的晶体内部空隙(用晶体表观密度表征)、颗粒度和形貌对包括冲击波感度和撞击感度在内的冲击感度的影响规律。冲击波感度测试采用隔板试验,药柱配方为RDX/食用油(质量比为76/24),药柱采用液体填充方式制备。隔板试验研究表明:随着RDX晶体表观密度在1.7961~1.7983 g.cm-3范围内增加,炸药配方的冲击波感度降低,隔板厚度从14 mm降到12.2 mm,晶体表观密度与隔板厚度基本成线性关系;当晶体表观密度为1.7976 g.cm-3时,在50~600μm粒度范围内,随着颗粒度的增加,RD X炸药配方的冲击波感度降低,隔板厚度从13.5 mm降到12.3 mm;当晶体表观密度和颗粒度相近时,晶体颗粒的外观形貌对炸药冲击波感度影响不大。落锤撞击试验表明:RD X颗粒度对撞击感度影响较大,当平均颗粒直径在16.7~337.9μm范围时,随着粒径的增加,特性落高从75 cm降到35.8 cm,颗粒越大撞击感度越高;当颗粒度相近时,在1.7961~1.7983 g.cm-3范围内,RDX晶体表观密度对撞击感度几乎无影响。     

NEPE含能组份冲击响应细观对比分析

制备NEPE含能组分AP（III）、AP（IV）、HMX（200目筛下物）、HMX（6）、RDX（5）、RDX（7）粉体样品,通过落锤仪对样品进行落锤冲击实验,并对冲击前样品和冲击过程中具有典型现象的样品做电镜扫描观测,对比冲击前后样品细观层次上的变化,分析各类型样品受冲击载荷后细观层次上的响应。     

复杂应力动态加载下颗粒增强复合材料失效模式研究

为解决战斗部颗粒增强复合材料因装药损伤引起局部"热点"而发生提前起爆问题,对颗粒增强复合材料在复杂应力动态加载下的损伤特性进行研究。基于一级轻气炮,对颗粒增强复合材料在三轴向冲击载荷作用下的损伤失效模式进行试验研究,分析轴向和径向边界约束条件对颗粒增强复合材料宏观损伤形式的影响,利用扫描电子显微镜(SEM)探索冲击载荷与细观损伤模式的内在关联。结果表明:颗粒增强复合材料宏观损伤特性主要表现为挤压变形;晶体颗粒表面与黏结剂剪切脱黏强度约为0.3 MPa,在较小冲击载荷作用下,颗粒表面与黏结剂已产生剪切脱黏,随冲击载荷的增大,出现晶体颗粒"孪晶带",大尺寸颗粒易受到应力集中影响,先于小尺寸颗粒发生断裂破坏,急剧冲击波能量迫使颗粒表面微裂纹发生断裂,从而演变成整个颗粒破碎情况,甚至部分出现融化现象。     

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.