基于矢量最优化的稳健波束形成方法

当阵列导向矢量存在误差或接收信号采样样本数较少时,标准Capon波束形成（SCB）的性能会严重退化。现有的提高稳健性的算法大都是针对导向矢量误差而提出的,很少考虑有限采样效应条件下的稳健性问题。针对以上原因,从导向矢量误差和有限采样效应两个角度出发,引入矢量最优化概念,提出了基于矢量最优化的稳健波束形成(VORB)方法,进而提高SCB算法的稳健性,并通过二阶锥(SOC)规划理论对其进行求解。文中还进一步推导了自适应权矢量的近似解析表达式,揭示了影响最优权矢量的各主要因素之间的关系,同时证明了该算法广义上属于对角加载类方法。通过理论分析和计算机仿真研究,表明了VORB方法对自适应波束形成算法的稳健性有明显的改善：在不同快拍数、信噪比(SNR)和导向矢量不确定度条件下,VORB方法的输出信干噪比(SINR)均较其他算法提高约5 dB;在典型工况条件下,VORB具有更尖锐的谱峰,更低的旁瓣级（低至-15 dB以下）。外场试验数据处理结果表明,将VORB应用于实际工程进行空间谱估计,能够得到准确而稳健的高分辨方位估计结果。     

联合协方差矩阵重构与导向矢量校正的稳健波束形成方法

针对强期望信号和导向矢量失配同时存在时,波束形成器性能会急剧下降的问题,提出联合协方差矩阵重构与导向矢量校正的稳健波束形成方法。该方法利用空间功率谱积分重构干扰加噪声协方差矩阵,排除了采样协方差矩阵中的强期望信号分量,通过空间投影方式校正导向矢量,用校正导向矢量和重构矩阵计算最优加权矢量,进而进行波束形成。仿真实验表明,相较于重构协方差矩阵,校正导向矢量等方法,该方法在强期望信号和期望信号导向矢量失配同时存在时具有更好稳健性,在不同信噪比、不同快拍数、不同失配角度时,输出信干噪比性能接近最优波束形成。     

基于最小二乘估计的声矢量阵稳健波束形成

针对存在导向矢量失配和快拍数不足时,声矢量阵标准Capon波束形成器性能急剧下降的问题,提出了一种基于最小二乘估计的声矢量阵稳健波束形成算法。鉴于声矢量阵声压通道和振速通道的导向矢量误差来源不同,分别为声矢量阵声压通道和振速通道设计了广义旁瓣对消器;利用最差性能最优化的思想,将声矢量阵标准Capon波束形成器转化为稳健最小二乘估计问题;利用二阶锥规划求解。仿真分析表明,该算法在抗导向矢量失配、快拍数不足、阵元姿态误差方面均有良好的性能。     

一种新的基于角度分布的自适应波束形成算法

文中针对自适应波束形成算法对指向误差敏感的缺点,将由先验知识得到的角度进行均匀扩展,然后将该范围内所有角度的方向矢量进行累加,得到一个新的平均导向矢量,并将该矢量代替原始的波束形成算法的导向矢量,从而得到一种较稳健的自适应算法.经过证明,文中新的导向矢量可以通过对原有导向矢量的数值计算得到,并没有增加运算量,计算机仿真的结果,证明了该算法可以有效工作于存在指向误差的环境下.算法的稳健性得到了提高.     

基于协方差矩阵重构稳健波束形成算法

提出了一种新的基于协方差矩阵重构的稳健算法.该算法基于最小化输出期望信号空间倒谱,利用多项式拟合估计期望信号的导向矢量;从数据协方差矩阵中减去期望信号部分,得到干扰加噪声协方差矩阵,通过修正方法实现对干扰加噪声协方差矩阵的准确估计,解决了低信噪比时由于信号子空间发生缠绕,导致协方差矩阵估计存在较大误差的问题;理论分析与仿真实验表明了该算法的有效性和稳健性.     

基于多普勒信息的盲波束形成方法在声呐信号处理中的应用研究

本文针对水声环境和水声信号的特点，提出了一种可用于任意阵形的自适应神经网络盲波束形成方法。该方法在未知基阵响应向量的情况下，利用水声信号多普勒频率信息，估计波束形成的权矢量，采用神经网络的方法实现盲波束形成，从而避免了矩阵的求逆运算，不但减小了运算量而且易于用硬件实现。此外该算法具有收敛速度快、鲁棒性强、估计精度高等优点。通过拖曳阵和体积阵的仿真实验，验证了所提出方法的有效性和正确性。     

基于幅度响应约束的稳健自适应宽带波束形成

针对信号方向失配会导致自适应波束形成算法的性能急剧下降这一问题,提出一种基于幅度响应约束的稳健自适应宽带波束形成方法。通过对阵列波束指向附近范围内的波束幅度响应施加约束来克服对信号方向失配的敏感性,并结合频率不变技术,使阵列波束图在主瓣区域内波束图近似保持频率不变特性,然后采用参考频率上幅度响应约束的优化方法来确定最优权值。仿真结果表明:与基于最差情况性能最优的稳健方法相比,该方法复杂度低,能灵活控制稳健的方位区域宽度和幅度响应抖动值,且不仅能有效地控制波束主瓣区域内信号的畸变,还改善了阵列输出的信干噪比,使其更接近最优值。     

一种新的频域自适应波束形成算法

在分析传统自适应波束形成的基础上，提出了一种新的频域自适应波束形成算法。该波束形成算法先对输入信号进行FFT，然后在空间频域上带通滤波，最后.通过LMS(最小均方）算法实现自适应波束形成。FFT变换后信号自相关下降，LMS算法收敛速度提高；空间频域上帯通滤波可以消除带外的干扰信号，实现容易；带通滤波后的信号维数大大下降，LMS算法计算量和存储量大大降低，收敛速度进ー步提高。理论分析和仿真结果表明了该算法收敛速度很快、性能较好，且计算量和存储量较少，易于实时实现。     

双重优化的宽带聚焦波束形成算法研究

在相干信号子空间法中确定聚焦矩阵时,对初始方向估计的偏差和聚焦频率选择的偏差都会影响最终的聚焦效果,甚至会使算法失效。针对这个缺陷,提出了一种双重优化的宽带聚焦波束形成算法。该算法利用稳健Capon波束形成算法对聚焦矩阵进行修正,使宽带信号通过修正的聚焦矩阵全部聚焦在最佳聚焦频率上,再对窄带数据利用2阶锥方法实现波束形成。计算机仿真以及湖试实验结果表明,该算法在保证波束恒定的前提下,在各个频率点都具有更低的旁瓣级。     

基于遗传算法的稀疏子阵布阵优化软件

为降低相控阵雷达天线的系统复杂性及硬件成本,采用稀疏阵列和子阵技术对天线阵面进行稀疏优化布 阵。对稀疏子阵的布局优化进行分析,基于遗传算法研究优化后的稀疏子阵布局;对稀疏子阵波束形成算法进行设 计,通过采用二级加权法,先对子阵内部阵元采用固定加权法获取阵元级权矢量,再对子阵级数据采用自适应波束 形成算法求取子阵级最佳权矢量,从而实现稀疏子阵的波束形成;设计子阵优化布局与波束形成应用软件。结果表 明：该软件具有良好的人机交互界面,可对天线稀疏优化设计起到较好的辅助和验证作用,有效提高天线阵列优化 设计自动化程度。     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

A Robust Algorithm for Watermarking 2D Vector Maps with Low Shape-Distortions

The technique of watermarking has been introduced into 2D vector maps for many potential applications such as protecting the copyright of important GIS （geographical information system） data and tracing the data source of military maps. In most previous works, although the validity of the map data could be preserved during the embedding procedure, the shape-distortions of the map elements are usually neglected which would tend to degrade the invisibility of the watermarking schemes. A shape-preserving algorithm for watermarking 2D vector maps is presented in this paper. A 1D distance sequence extracted from the original map is adopted as the cover data instead of 2D coordinates. A watermark bit is represented by changing the distributions of the cover data. The embedding procedure induces lower shape-distortions than in former works. Experimental results indicate better invisibility of the proposed scheme, as well as its robustness to certain attacks such as map simplification, interpolation, additive noise and most geometric transforms.     

Open Rule-setting System Applied to Conceptual Design of Engines

Open rule-setting method advanced in this paper concentrates on providing designers of engines with a convenient way to express their design innovations and develop the expected prototypes in the early CAD stage, and constitute effective models for the following analysis process of CAE and CAPP. The problems arisen in the process of conceptual design with the traditional experience-based development method are analyzed. Based on those analyses, open rule-setting method is presented and some associated technical problems are discussed. The functional framework of open rule-setting system was built as software engineering methods. The speciality of the engine product as a kind of complex product and the requirement of the engine product based on its structural particularity to rule-setting system are considered carefully. A demonstration is supplied to illustrate how the open rule-setting method enhances the efficiency and quality of the engine conceptual design.     

Research on Linux Network Device Driver

By analyzing the working principle of Linux network device driver, discussing the Linux network driver structure and its key technologies, the general network driver structure and its design methodologies in Linux system are summarized. Through modifying the network device driver of Linux device driver 3rd version snull, c and improving the COW technology, the Zero-Copy technology in Linux （kernel version 2.6.11 ） is implemented. In the end, the success test tells us that the thorough analysis of network device driver is the foundation of many applications, and it also provides a certain improvement to a lot of real applications, even to military application development.     

Improvement and Experiment of the Reamer in Vibra Cutter Against Wave Edge of Titanium Sheet Alloy Parts

By analyzing the influencing factors of part quality making of sheet alloy of titanium by vibra cutter, the shape of upper reamer is set as cylinder and wedge-shaped form, and the lower reamer as plain and hemicycle form, and its main structural parameters are defined as well. Then it is validated further that such improved vibra cutter reamer can be used to process curve-edged parts of titanium alloy sheet. The experimental result shows that the titanium alloy sheet parts processed by above equipment have no sharpen angles for convex parts and evident crevasse of concave-edged part. In summary, such improvement can eliminate the free-waved edge and improve the manufacture quality of titanium alloy sheet parts greatly.     

Experimental Study on the Small Flyer Initiating Behavior of Fine-grained Explosives

The initiating behavior of fine-grained explosives by small flyer is studied. The diameter of small flyer in this device is 1 ram. The test results indicate that the granularity of explosives has great effect on its flyer initiating sensitivity.The flyer initiating sensitivity of the fine-grained explosives is higher and the critical initiating energy is lower than that of common explosives. For common explosive, the flyer initiating sensitivity increases as the density is reduced. But for the fine-grained explosive, the test results are exactly opposite.     

Algorithm for Multi-laser-target Tracking Based on Clustering Fusion

Multi-laser-target tracking is an important subject in the field of signal processing of laser warners. A clustering method is applied to the measurement of laser warner, and the space-time fusion for measurements in the same cluster is accomplished. Real-time tracking of multi-laser-target and real-time picking of multi-laser-signal are introduced using data fusion of the measurements. A prototype device of the algorithm is built up. The results of experiments show that the algorithm is very effective.     

Influence of Installing Error on the Surface Shape Precision of the Axial Symmetry Aspheric Workpiece in Lapping

A method to calculate the surface shape error, which is caused by the installing error between the workpiece and the lapping tool in the process of form lapping, is proposed. The mathematical model which the installing translation error influences on the workpiece surface shape error is established. The changing rule of the error is simulated through the calculating example of the paraboloid workpiece. The results indicate that the surface shape error of the workpiece is increasing with the increase of the installing translation error, it is also increasing gradually along the center point of the curve surface to the edge, and the influence is severer to the curve surface with great curvature than that of the small curvature when the translation error is the same.     

Experimental Research on Output Performances of Giant Magnetostrictive Actuator

The paper introduces the performances of magnetostrictive actuators and its applications, discusses the design methods for the structure and internal magnetic circuit of a giant magnetostrictive actuator, and makes tests on the output displacement and force characteristics for an actuator using homemade magnetostrictive material. The experimental result shows that the actuator has satisfactory output precisions and ranges in transient and stable states, and can be used in lowfrequency vibration control system of precise equipment.     

Robust Graded Sliding Mode Tracking Control for Low Speed Spinning Ballistic Missiles

The nonlinear dynamic model of spinning ballistic missiles is established during the first boosting phase of the missile. Based on the conventional backstepping sliding mode control and the assumption of a two time-scale separation of missile dynamics, a graded sliding mode controller is designed with two sub-sliding surfaces which have invariability to external disturbances and parameter perturbations, and a matrix which comprises three first order low pass filters is introduced to prevent ＂explosion of terms＂. Owing to the upper bounds of the uncertainties are difficult to obtain in advance, adaptive laws are introduced to estimate the values of the uncertainties in real-time. Eventually, the numerical simulation results given to show the proposed controller can ensure the steady flight of missiles.