低空无线电扩频引信的测距算法研究

研究分析了扩频技术在低空无线电引信应用中的相关问题,给出了引信回波模型,提出了基于软件无线电扩频引信的接收机结构和相应的测距算法,并对其性能进行了软件仿真,证明了在引信中应用的可行性。     

无线电导航系统扩频码的优选与仿真

针对无线电测距对扩频码的特殊要求,通过对传统的扩频码的比较分析,提出在无线电导航系统中引入移位序列作为扩频地址码。并对其相关特性进行仿真,通过仿真可知,它改进了测距扩频码 m 序列的互相关特性和 Gold 序列的自相关特性,从而提高了系统的性能,成为无线电导航系统扩频码的最优选择。     

多频脉冲测距技术在引信中的应用研究

提出了一种应用在大炸高无线电引信中的多频脉冲测距算法。建立了多频脉冲测距模型;提出了基于相位比对的多频脉冲测距算法,给出了该算法的参数选择方法;从理论上对算法的性能进行了分析;对测距算法进行了软件仿真。仿真结果表明了该算法的可行性和有效性。     

高动态中频直扩接收机的设计与实现

简要说明了空战环境中的数据链系统工作原理,介绍了基于软件无线电的中频数字化扩频接收机设计方案。它采用AD6645加FPGA构成核心单元,通过不同的软件配置可实现对不同扩频信号的解扩解调     

序列分割技术在无线电定位中的研究

文中研究了一种无线电定位的新方法，该方法首先将直接序列的扩频信号分成两路低速的窄带信号，然后每路窄带信号再调制互相正交的载波发射，在接收端恢复出原来的高速直扩信号，再使用常规方法得到传输时延，测量出目标的距离。通过分析和仿真，将常规直扩系统的性能和该扩频测距系统的性能做了比较，结果证明在码噪声可忽略的情况下，该方法在带宽仅占常规直扩系统一半的情况下，能够达到与常规直扩测距系统几乎完全相同的测距不确定性，有效地利用了频谱。     

毫米波双频比相定距引信

单频多普勒体制无线电引信在对地面作用时,由于存在不具备测距能力,炸高散布大等缺点,故采用双射频收发回路的多普勒体制无线电引信。通过对双路射频回波的多普勒信号进行相位比较,完成了作用距离的测量。针对引信对地作用的需要,论述了采用双频比相探测体制的测距、测速毫米波引信的测量原理、系统构成方法、系统的关键技术及系统特点等。     

一种16APSK 信号的载波恢复方案设计

针对多幅度高阶 APSK 信号对多普勒频偏的敏感性和载波恢复算法的复杂性,为了探索适用于 APSK 的载波恢复方案,借鉴高阶 QAM调制系统的载波恢复算法,提出了一种对16APSK 信号三次方非线性变换后联合使用极性判决算法和面向判决算法的载波恢复方案;仿真结果表明：该方案频偏捕获范围大,能达到系统符号率的5．4％,稳态抖动方差较小为0．6,具有较强的实用价值。     

GPS软件接收机相关技术研究

随着卫星导航接收机的发展,软件定义的接收机因其设计的灵活性成为下一代导航接收机的发展趋势。研究了基于GPS软件接收机结构方案;采用基于FFT的并行码相位搜索算法处理卫星信号的捕获问题;分析基本锁相环的原理,并设计可用于软件接收机的码跟踪环和载波跟踪环;根据GPS完好性的要求,设计GPS自主监测算法。实验表明,所设计的软件接收机能较好地对卫星信号进行捕获,可准确跟踪含有多普勒频移的载波,并能正确解调出导航数据,同时可对接收机的完好性进行监测。     

基于软件无线电平台的低轨卫星扩频通信的信号快速捕获和跟踪

本文针对低轨卫星直接序列扩展频谱(DSSS)通信中的信号同步问题,提出了基于软件无线电平台的处理方法.采用了二维联合搜索的快速算法,同时捕获扩频信号的载频和码起点.在持续跟踪中,利用匹配滤波器的相关重构,并采用频率、相位细分和多帧叠加处理的抗噪算法,较好地解决了大动态范围多普勒频移的跟踪难题,同时也对码起点的持续漂移进行了良好的同步处理.最后,给出了试验数据和分析、改进,为低信噪比下的扩频通信提供了重要的技术参考.     

高动态扩频信号捕获的多普勒补偿

分析了多普勒效应对扩频信号捕获的影响,介绍了对载波多普勒和伪码多普勒频率的补偿方法,研究了对于多普勒变化率的补偿方法,并对该方法进行了相应的仿真。仿真结果表明,引入补偿之后,能够有效减少多普勒频移和变化率对于扩频信号捕获的影响,提高捕获门限。     

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.     

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.     

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。     

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.