金属桥箔水中电爆炸流场数值模拟研究

研究金属桥箔水中电爆炸等离子体特征及其流场变化规律,建立了桥箔水中电爆炸过程的多相流数值计算模型和计算方法。采用相变分数,实现了金属从固相到气相的质量传递计算。利用Saha电离平衡方程计算了等离子体的电离度,给出了考虑粒子数目变化及粒子间库仑作用的等离子体状态方程。对桥箔水中电爆炸过程进行了数值模拟计算,获得了桥箔电爆炸等离子体及冲击波形状特征,给出了桥箔水中电爆炸流场压力、温度、密度及速度等重要参数的变化规律。     

桥丝电爆炸过程中的电磁脉冲效应

金属桥丝爆炸实验中,金属桥丝是否完全电起爆对火工品能否正常发火十分重要,为此,提出了一种通过电磁脉冲辐射效应来判断桥丝起爆状态的方法,利用天线探测金属桥丝在起爆中的电磁脉冲信号,并对其进行分析以判断桥丝起爆状态。研究结果表明,完全电起爆和不完全电起爆状态产生的电磁脉冲在持续时间和辐射频谱上存在显著差异。当桥丝完全电起爆时,金属桥丝初始加热阶段的电磁效应和本征爆炸阶段的电磁效应产生的电磁信号持续时间短,等离子体阶段的电磁效应产生的电磁信号持续时间长,电磁脉冲信号中包括90～100 MHz高频电磁辐射;当桥丝没有完全电起爆时,金属桥丝初始加热阶段的电磁效应和本征爆炸阶段的电磁效应产生的电磁信号持续时间长,等离子体阶段的电磁效应产生的电磁信号持续时间短,电磁脉冲信号的频率主要集中在40 MHz以下的低频区域。     

桥箔电爆炸过程数值计算分析

为了研究金属电爆炸特征,编制了计算金属导体电爆炸放电回路的程序,对桥箔爆炸物理过程进行了数值计算,得到了金、铜、金-铂合金及铝四种金属桥箔爆炸的爆发电流和动态电阻.分析了起爆回路电参数和金属桥箔几何参数变化对爆发电流的影响规律.     

介电式AI/CuO复合薄膜点火桥的电爆性能

提出了“介电式复合薄膜点火桥”的概念,并以AI膜作电极,CuO膜作电介质层,用微细加工技术制备了介电式Al/CuO复合薄膜点火桥样品,尺寸为2000μm x2000 μm x2.6 μm,电阻值约4Ω.用60 V以上恒压源可激发点火桥发生电爆炸,电爆过程中Al/CuO复合薄膜发生了氧化还原反应,生成的单质Cu使点火桥产生了延迟放电效应.用原子发射光谱双谱线法测试了60 V和80 V激发时点火桥的电爆炸温度和持续时间.60 V激发时点火桥电爆炸温度主要分布在2500 ～3500 K,持续时间约0.35 ms;80 V激发时点火桥电爆炸温度主要分布在3500 ～4000 K,持续时间约0.55 ms.     

电爆炸桥箔电导率模型研究

电爆炸桥箔是冲击片雷管的重要组成部分，其电导率是电爆炸过程中的重要参数。在分析桥箔状态变化的物理原理基础上，提出了将电导率分3个阶段来讨论：桥箔加热初始阶段、本征爆炸阶段和等离子体阶段。根据各个阶段的特点，建立了电爆炸过程桥箔电导率的计算模型。用此模型模拟的结果与实验结果具有很好的一致性。     

可储能电装甲箔电极爆炸温度的一种计算方法

可储能电装甲作为一种新型的电装甲,其防护性能与箔电极爆炸时等离子体温度密切相关。从电装甲的电爆炸机理出发,对其核心脉冲电容器爆炸时的箔电极的电流、电阻和表面积的计算进行了分析求解,进而提出了其箔电极爆炸时产生的等离子体温度的一种计算方法。     

光谱辐射测量金属薄膜桥电爆炸温度

采用光谱辐射法测量了Ni-Cr金属薄膜桥的电爆炸温度。通过六通道瞬态光学高温计测量金属薄膜桥电爆炸时在514nm、631nm、692nm、715nm、910nm、1068nm波长处的辐照强度，根据黑体辐射理论计算温度值。研究表明，金属薄膜桥在50V、100μF条件下电爆炸时的最高温度在5000K左右，4000K以上持续时间为300ns。     

高压脉冲功率源等效参数对桥箔电爆性能影响规律

为了降低冲击片雷管起爆能量,优化高压脉冲功率源等效参数,研究了高压脉冲功率源等效参数如等效电感、等效电阻、电容量、电压等参数对金属桥箔电爆特性规律的影响,测试了金属桥箔在不同的等效参数条件下,其电爆性能的变化规律参数,计算了金属桥箔的能量利用率,实验结果表明:当高压脉冲功率源储能电容容量为0.2μF,放电回路等效电感为57 n H,等效电阻为68 mΩ时,在加载电压为2.0 k V放电条件下,桥区厚度为5.0μm,尺寸为0.5 mm×0.5 mm的铜箔其爆发性能最优,有效能量利用率达到最高,为54.8%,此时桥箔的爆发时间与峰值时间最为接近,时差最小。     

爆炸箔起爆器作用机理研究进展

从金属桥箔电爆炸、电爆炸驱动飞片和飞片冲击起爆炸药三个方面,综述了爆炸箔起爆器作用机理的研究进展。认为:爆炸箔起爆器在分段式电阻率模型、先进飞片测速技术、基于能量转化系数的电爆炸驱动飞片速度计算模型和基于临界起爆判据的感度预测等方面取得了重要进展,获得了一些规律性认识,一定程度上促进了其低能化设计。指出:小尺寸条件下电爆炸驱动飞片过程中的能量耗散及飞片烧蚀的定量描述、飞片在飞行中的瞬时形态、爆炸箔起爆器小尺寸装药的非理性爆轰性能预测、波阵面后微流场观测技术将成为爆炸箔起爆器未来研究的重点。     

桥丝式电火工品热点火理论

定义了热点火温度,将桥丝式电火工品的热点火过程分为升温阶段和爆炸阶段.在升温阶段建立桥丝电热升温模型,分别求解恒定电流点火升温时间和电容放电点火升温时间.在爆炸阶段建立绝对超临界化学放热模型,求解爆炸时间.根据热点火温度的定义,求解出热点火温度的表达式.根据本理论,应用MATLAB的数组运算进行桥丝式电火工品的设计,并给出了一个算例.     

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.