特征信号检测法

本文以信号极点的不变性为基础,构造了一种用于可自设计的主动式系统在强噪声背景下的极微弱信号检测的检测器——特征信号检测器。文章在分析经典检测方法对极弱信号检测存在的问题的基础上,提出了特征信号检测的思想。讨论了该方法的基本原理及仿真实验结果。Monte carlo实验表明,这种特征信号检测器的性能对信噪比不敏感,可以在极低信噪比下检测出微弱信号。     

丁羟（HTPB）推进剂老化研究（IV）——过氯酸铵（AP）粒度对老化性能的影响

本文研究了HTPB/AP推进剂中AP粒度对推进剂老化性能的影响。实验是在90℃的空气中进行的。老化性能以推进剂的拉伸性能、邵氏硬度,失重%和燃烧速度等参数为判据,并以DSC图谱作参考。实验结果表明:HTPB/AP推进剂中AP粒度的减小,有助于推进剂贮存老化性能的提高。各种粒度AP的DSC图谱,也进一步证实了这一结论。     

多窗口谱图分析的低截获概率雷达信号识别

在当前复杂的战场环境中,低截获概率雷达信号因其具有大时宽带宽积、强干扰性能、高分辨率和低截获性特点得到了广泛应用,传统的雷达侦察手段很难对其进行有效识别.在低截获概率雷达典型调制分析的基础之上,研究基于人工智能的雷达信号分类识别方法.从低截获概率雷达信号时频特征入手,提出基于多窗口时频谱图分析方法.该算法采用Hermi...     

基于倒谱分析的低信噪比瞬态声信号检测方法

低信噪比条件下,瞬态信号能量被噪声信号能量淹没,造成传统信号检测器性能下降甚至失效。为了解决该问题,首先根据信号能量在倒谱域的衰减特点,提出了一种低信噪比条件下的瞬态声信号检测新方法;然后,分别对接收信号进行倒谱计算,将倒谱序列用EMD分解为IMF,第一阶分量中幅值最大的脉冲尖峰即对应瞬态信号到达时刻;最后,选用美国海军水下战中心给出的典型瞬态信号模型进行理论推导,并通过数值仿真及系泊实验进行了效果验证。实验结果表明,与传统瞬态信号检测方法相比,倒谱域检测方法在低信噪比条件下能取得良好的检测效果。     

围压下固体推进剂的破坏机理分析

贴壁浇筑的固体发动机推进剂药柱在点火状态下处于三向围压状态,而环向承受拉应变,亟待对围压下推进剂的破坏机理展开研究。基于自研的围压加载试验系统,通过开展推进剂在不同围压、温度和应变率下的单轴拉伸试验来研究围压、温度和应变率的耦合作用对推进剂力学行为的影响。针对围压下推进剂的力学响应特征,通过细观力学仿真进一步研究围压下推进剂的破坏形式,同时借助电镜扫描试验分析推进剂试样断面的形貌特征,通过试验和仿真相结合的手段分析了围压下推进剂的破坏机理。研究结果表明,围压下推进剂的损伤界面显著减少,且随着围压载荷的逐渐增加,推进剂的损伤形式从以颗粒脱湿为主转变为以颗粒破碎为主。     

聚氨酯型复合推进剂的性能研究

本文研究聚氨酯型复合推进剂的力学性能和燃烧性能,给出了提高推进剂力学性能的有效途径,测试了推进剂燃烧性能的基本特征参数,采用光电子能谱(ESCA)对这种复合推进剂的界面作用机理进行了微观探讨.     

雷达利用极化信息区分真假目标浅析

首先介绍了电大目标回波信号极化特征和电子假目标信号极化特征,接着探讨了理论上雷达根据极化信息区分电子假目标信号和真实目标回波信号的方法,分析了实际应用中可能存在的困难,说明了这种方法在目前和今后雷达目标识别技术发展中是有实际意义的。最后说明了无论是现在,还是今后,极化信息对于雷达目标识别来说都是一个极其重要的参数。     

具有离解反应的推进剂高压蒸发理论探讨

文中提出了具有液相离解反应的推进剂液滴高压蒸发模型,同时还考虑了燃气中极性气体成份对液滴蒸发的影响,并以N_2O_4推进剂液滴为例分析了具有液相离解反应的推进剂蒸发规律。结果表明,此类推进剂高压蒸发并不服从非液相离解反应推进剂的t_b～(?)。规律。模型的提出为液体火箭发动机燃烧室燃烧过程分析提供了新的液滴蒸发理论数据和计算方法。     

雷达调频编码脉冲信号的设计与处理

现代雷达为获得较高的距离分辨力通常采用编码频率脉冲串信号和步进频率脉冲串信号,但都存在数据率低和较为严重的距离-多普勒耦合问题。在研究这两种信号特点的基础上,提出了调频编码脉冲信号形式并给出了相应的信号处理方法。经仿真对比可见,该信号形式及其处理方法能同时解决步进调频信号高距离-多普勒耦合、低数据率两大问题,具有较好的联合分辨力。     

嵌银丝贫氧推进剂燃烧特性

采用试验发动机法 ,对嵌银丝铝镁贫氧推进剂的燃烧特性进行了研究 ,得到了低压下嵌银丝铝镁贫氧推进剂的燃烧规律 ,研究了银丝直径和贫氧推进剂配方对嵌银丝发动机燃速的影响。结果表明 ,嵌银丝贫氧推进剂的燃烧过程由初始工作段、稳定工作段和结束段组成 ;采用较粗的银丝 (0 3mm和0 4mm)可以显著提高贫氧推进剂的燃速 ;提高贫氧推进剂的基础燃速也是提高嵌银丝贫氧推进剂燃速的有效方法之一。     

Deconsolidation and combustion performance of thermally consolidated propellants deterred by multi-layers coating

Both heating and solvent-spray methods are used to consolidate the standard grains of double-base oblate sphere propellants plasticized with triethyleneglycol dinitrate (TEGDN) (TEGDN propellants) to high density propellants. The obtained consolidated propellants are deterred and coated with the slow burning multi-layer coating. The maximum compaction density of deterred and coated consolidated propellants can reach up to 1.39 g/cm³. Their mechanic, deconsolidation and combustion performances are tested by the materials test machine, interrupted burning set-up and closed vessel, respectively. The static compression strength of consolidated propellants deterred by multi-layer coating increases significantly to 18 MPa, indicating that they can be applied in most circumstances of charge service. And the samples are easy to deconsolidate in the interrupted burning test. Furthermore, the closed bomb burning curves of the samples indicate a two-stage combustion phenomenon under the condition of certain thickness of coated multi-layers. After the outer deterred multi-layer coating of consolidated samples is finished burning, the inner consolidated propellants continue to burn and breakup into aggregates and grains. The high burning progressivity can be carefully obtained by the smart control of deconsolidation process and duration of consolidated propellants. The preliminary results of consolidated propellants show that a rapid deconsolidation process at higher deconsolidation pressure is presented in the dynamic vivacity curves of closed bomb test. Higher density and higher macro progressivity of consolidated propellants can be obtained by the techniques in this paper.     

Investigation on the foaming behaviors of NC-based gun propellants

To prepare the porous NC-based (nitrocellulose-based) gun propellants, the batch foaming process of using supercritical CO₂ as the physical blowing agent is used. The solubilities of CO₂ in the single-base propellants and TEGDN (trimethyleneglycol dinitrate) propellants are measured by the gravimetric method, and SEM (scanning electron microscope) is used to observe the morphology of foamed propellants. The result shows that a large amount of CO₂ could be dissolved in NC-based propellants. The experimental results also reveal that the energetic plasticizer TEGDN exerts an important influence on the pore structure. The triaxial tensile failure mechanism for solid-state nucleation is used to explain the nucleation of NC-based propellants in the solid state. Since some specific foaming behaviors of NC-based propellants can not be explained by the failure mechanism, a solid-state nucleation mechanism which revises the triaxial tensile failure mechanism is proposed and discussed.     

高能硝胺推进剂的压强指数分析

从高能硝胺推进剂配方组成入手 ,深入研究了各组分参数的变化对该推进剂燃烧性能的影响 ,认为 :高硝胺 ( HMX或 RDX)含量和高硝酸酯增塑剂含量是高能硝胺推进剂 ( NEPE)高压强指数的根本原因。同时指出该类推进剂的燃烧性能的调节将不再仅仅局限于硝胺的催化 ,而应针对硝胺和硝酸酯及 AP的特殊作用进行综合调节     

Formulation development and characterization of cellulose acetate nitrate based propellants for improved insensitive munitions properties

Cellulose acetate nitrate (CAN) was used as an insensitive energetic binder to improve the insensitive munitions (IM) properties of gun propellants to replace the M1 propellant used in 105 mm artillery charges. CAN contains the energetic nitro groups found in nitrocellulose (NC), but also acetyl functionalities, which lowered the polymer's sensitivity to heat and shock, and therefore improved its IM properties relative to NC. The formulation, development and small-scale characterization testing of several CAN-based propellants were done. The formulations, using insensitive energetic solid fillers and high-nitrogen modifiers in place of nitramine were completed. The small scale characterization testing, such as closed bomb testing, small scale sensitivity, thermal stability, and chemical compatibility were done. The mechanical response of the propellants under high-rate uni-axial compression at, hot, cold, and ambient temperatures were also completed. Critical diameter testing, hot fragment conductive ignition (HFCI) tests were done to evaluate the propellants' responses to thermal and shock stimuli. Utilizing the propellant chemical composition, theoretical predictions of erosivity were completed. All the small scale test results were utilized to down-select the promising CAN based formulations for large scale demonstration testing such as the ballistic performance and fragment impact testing in the 105 mm M67 artillery charge configurations. The test results completed in the small and large scale testing are discussed.     

少烟推进剂配方优化设计

本文报道了关于降低固体火箭发动机喷气羽烟对微波、激光制导信号的干扰和衰减的研究成果——一种少烟HTPB推进剂。它具有低压点火性能良好,燃烧稳定,能提高排气羽烟对微波和激光透过率三倍以上。     

非壅塞固体火箭冲压发动机及其贫氧推进剂

研究了非壅塞固体火箭冲压发动机的工作特性。研制出了能量高、燃速高、燃速压强指数高、低压燃烧性能好的铝镁贫氧推进剂配方。采用连管式试验与数值分析相结合的方法 ,对非壅塞固体火箭冲压发动机性能进行了系统的研究     

点火瞬态过程对复合固体推进剂力学响应特性的影响

根据一个有效的非线性粘弹模型,导出复合固体推进剂微分形式本构方程和应变速率关系式。分析表明点火瞬态过程中压强与推进剂应变、升压速率与推进剂应变速率之间呈线性关系,线性系数均为推进剂初始模量。     

Recent advances in catalytic combustion of AP-based composite solid propellants

Composite solid propellants (CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust velocity, specific impulse, thrust, burning rate etc., are measured to assess and control the performance of rocket motors. The burn rate of solid propellants has been considered as most vital parameter for design of solid rocket motors to meet specific mission requirements. The burning rate of solid propellants can be tailored by using different constituents, extent of oxidizer loading and its particle size and more commonly by incorporating suitable combustion catalysts. Various metal oxides (MOs), complexes, metal powders and metal alloys have shown positive catalytic behaviour during the com-bustion of CSPs. These are usually solid-state catalysts that play multiple roles in combustion of CSPs such as reduction in activation energy, enhancement of rate of reaction, modification of sequences in reaction-phase, influence on condensed-phase combustion and participation in combustion process in gas-phase reactions. The application of nanoscale catalysts in CSPs has increased considerably in recent past due to their superior catalytic properties as compared to their bulk-sized counterparts. A large surface-to-volume ratio and quantum size effect of nanocatalysts are considered to be plausible reasons for improving the combustion characteristics of propellants. Several efforts have been made to produce nanoscale combustion catalysts for advanced propellant formulations to improve their energetics. The work done so far is largely scattered. In this review, an effort has been made to introduce various combustion catalysts having at least a metallic entity. Recent developments of nanoscale combustion catalysts with their specific merits are discussed. The combustion chemistry of a typical CSP is briefly discussed for providing a better understanding on role of combustion catalysts in burning rate enhancement. Available information on different types of combustion nanocatalysts is also presented with critical comments.     

利用化学键能评估火箭推进剂的能量特性

本文介绍利用化学键能评估火箭推进剂的能量特性的方法