天线罩相关参数的改变对天线方向图影响

天线罩在保护雷达天线不受环境影响的同时,又会对天线的电磁辐射产生某些干扰,改变天线的电气性能。利用电磁场数值计算方法研究了在因气动、机械强度和耐热性等因素而需改变天线罩的厚度或材料的介电常数等相关参数时对天线方向图的影响,作为天线和天线罩的电磁相容性研究的参考。     

某机载VHF天线布局优化仿真分析

某研制机在飞机背部增加了卫星通信天线及天线罩,势必对安装于天线罩后方的VHF天线的辐射特性产生影响。通过对VHF天线辐射特性的仿真分析,给出了天线的最佳布局方案。布局方案及分析方法可以为其它机载天线布局优化设计提供参考。     

一种改进的天线罩瞄准线误差计算方法

基于对带罩天线的辐射方向图数据进行处理,提出了一种改进的天线罩瞄准线误差计算方法。该方法以单脉冲天线差方向图在电轴附近的对称性为理论基础,借助等电平平均法计算天线辐射方向图的零值位置,获取天线罩瞄准线误差,降低了测试场地对天线方向图的影响,有效提高了天线罩瞄准线误差的测试准确度。     

表面波对收发天线隔离度的影响及其解决方法

表面波引起的收发天线耦合是影响天线接收性能的重要因素。天线表面覆盖天线罩后,耦合信号能量明显增强,通过分析天线罩对表面波的激励作用,找到敏感参数,进而提出了降低耦合的方法,并通过仿真和实测验证。     

离散天线罩曲面电性能分析的方法及数值实现

研究了离散曲面天线罩的电性能分析方法．求解由天线方程与天线罩表面曲面样条函数联立的非线性方程组,得出天线罩表面积分的积分区域．使用平面波谱一表面积分方法,计算出带罩天线的远场方向图,得到较好的计算结果．为对天线罩外形进行修磨处理提供了依据．     

一种天线罩瞄准线误差测试的动态寻零方法

瞄准线误差的测试是评价天线罩电气性能必不可少的环节.文中提出了一种自动电轴跟踪的快速寻零方法.通过自动控制发射天线在扫描架上水平移动,跟踪接收天线在天线罩影响下的波束指向偏转,并记录移动距离.利用文中提出的方法对天线罩瞄准线误差进行测试,结果显示,天线的扫描范围减小了77％,测试时间仅为传统方法的0.36倍.可以看出,文中提出的动态寻零方法可有效缩短发射天线的扫描范围,提高测试速度.     

主被动复合天线罩瞄准线误差分析

在主被动复合的制导体制中，主动导引头和被动导引头分别采用幅度比较单脉冲系统和相位比较单脉冲系统情况下，天线罩所引起的瞄准线误差有一定的区别。从二种单脉冲天线的工作体制出发，分别分析了天线罩产生瞄准线误差的机理。采用这种天线罩瞄准线误差的分析方法，能评价主被动复合体制天线罩的电气性能。     

NURBS曲面拟合技术在三维天线罩分析中的应用

文中将NURBS技术引入不规则形状天线罩的罩面拟合中．提出了利用射线寻迹-表面积分法分析天线罩电性能的方法。通过对罩内阵列天线的计算证明．相对于三角面元拟合，应用NURBS分析获得了更准确的结果。     

多基线比相单脉冲雷达天线罩电性能测试技术

阐述了雷达天线罩的测试是天线罩研制中不可缺少的重要环节 ,其测试结果与测试天线关系极为密切 ,因此多基线比相单脉冲雷达的天线罩的测试必须使用相应的天线进行 .根据多基线比相单脉冲雷达天线的特点 ,提出了通过跟踪等相位线来测试瞄准误差的方法 .在寻零测试系统的基础上 ,采用单刀多掷开关进行时分接入各路信号的方式将天线接收信号轮流接入接收机 ,从而解决了天线的多路输出与接收机的单路输入的矛盾     

基于FEKO的天线罩瞄准误差分析

文中采用FEKO软件对天线罩的瞄准误差进行了仿真分析.直接对真实带罩天线进行仿真,计算量过于巨大,通常工作站难以支持,因此采用等效源方法进行仿真.仿真步骤如下:首先仿真天线口面附近的等效近场;然后将等效近场作为激励源放入天线罩模型中,计算带罩天线远场差方向图;对比带罩与无罩远场差方向图零点位置的变化得出天线罩的瞄准误差.仿真结果与实测结果吻合很好,验证了仿真方法的准确性.     

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.     

Method for Measuring Velocity of Warhead Fragments Based on Photoelectric Detection

For measuring velocity and impacting position of single fragment of warhead, a non-contact measuring method is proposed, in which a six-light-screen array, a position indicator, a multi-channel chronograph and a computer are used.The principle of measurement is described. The key device of the system is a light screen array sensor which consists of six light screens allocated with certain geometrical parameters. When the fragment flies through the light screen array, the time of passing through each of the screens is recorded by the multi-channel chronograph. According to the time data and the geometrical parameters of the array, the velocity vector and the location of the fragment can be calculated immediately. The presented method can be used to locate the fragment and to measure the real velocity on its flying direction. It can also be used to measure the velocity of a fragment swarm after the system is engineered further.     

数码电子雷管中影响点火头性能因素分析

阐述了数码电子雷管中,点火药剂细结晶三硝基间苯二酚铅（LTNR）的制备工艺;从点火药剂的种类、加入黏合剂的质量分数、桥丝直径、点火头的电阻值、防潮漆的蘸涂等方面对点火头性能的影响因素进行了探讨;通过震动试验、并联起爆试验、延期精度检测与考核,试验结果表明：一次性合成的细结晶LTNR是制造数码电子雷管点火头较为理想的点火药剂,按技术要求生产的点火头性能指标能够满足行业标准要求。     

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.