CFAR data fusion center with inhomogeneous receivers

Detection systems with distributed sensors and data fusion are increasingly used by surveillance systems. A system formed by N inhomogeneous constant false alarm rate (CFAR) detectors (cell-averaging (CA) and ordered statistic (OS) CFAR detectors) is studied. A recursive formulation of an algorithm that permits a fixed level of false alarms in the data fusion center is presented, to set the optimum individual threshold levels in the CFAR receivers and the optimum `K out of N' decision rule in order to maximize the total probability of detection. The algorithm also considers receivers of different quality or with different communication channel qualities connecting them with the fusion center. This procedure has been applied to several hypothetical networks with distributed CA-CFAR and OS-CFAR receivers and for Rayleigh targets and interference, and it was seen that in general the fusion decision OR rule is not always the best     

Improved strapdown coning algorithms

Three improved algorithms for strapdown attitude computation utilizing accumulated gyro increments from the previous and current update are developed and evaluated analytically under classical coning motion. The error criterion of Miller is derived directly from the rotation vector concept. The accuracy of updating rotation vector estimation can be improved at least two orders of magnitude as compared with those of conventional algorithms. The proposed algorithm is equivalent to increasing the number of gyro samples used in the conventional method and it requires less computer loading     

Modification of the SAR step transform algorithm

When the basic step transform algorithm is used to compress synthetic-aperture radar (SAR) signals in azimuth, the linear FM rate and sampling rate must satisfy certain tight constraints. In practice, these constraints cannot be satisfied and errors are introduced into the compressed SAR image. A modification is described of the basic step transform which incorporates interpolation and resampling into the algorithm. These changes allow the removal of the constraints and make the step transform more useful for the compression of real data. An autofocusing capability is also included, without introducing much additional complexity     

俄罗斯铝锂合金的研制和应用概况

本文介绍了俄国1420,1430,1450等铝锂合金的研制过程和性能,并与西方类似合金进行了对比,同时还列举了铝锂合金在战斗机、运输机、民航机和直升机上作为结构元件和应用情况。     

采用多级优化技术进行复合材料结构可靠性优化设计

在可靠性基础上将结构体系可靠性优化设计方法发展至复合材料结构,并采有多级优化技术提出了复合材料结构可靠性优化设计方法。系统级优化以结构总重最小为目标函数,以满足结构体系可靠性指标要求为约束条件;元件级优化以元件可靠度最大为目标函数,以层板或元件重量在一次迭代中保持不变为约束条件,从而导出了相应的优化准则和迭代式。算例表明该方法的效率高、收敛性好,能推广应用于大型复合材料结构。     

高超音速后掠激波与边界层干扰流场特性

应用表面油流和液晶温度显示、表面热流率和压力测量四种测试技术,在Ma_∞=7.8、单位长度雷诺数尺Re_∞=3.5×10~7/m条件下,研究了30°迎角尖前缘翼面诱导激波和湍流边界层干扰流场特性。结果表明:表面流动是准锥型,在强相互作用下,流动发生了二次分离和再附,导致表面油流线的流向角、温度、热流率和压力分布均出现明显的凹坑。     

铝锂合金的铸锭冶金（Ⅱ）

介绍了俄罗斯铝锂合金铸锭熔炼和铸造方法的发展和改进，评述了铝锂合金熔铸特点，熔体氧化，防护添加剂，熔剂和氩气防护，氧、碳、氮和氢等非金属夹杂，铸造裂纹（冷裂和热裂）敏感性，结晶状态，不均匀组织等方面的研究结果。     

惯性导航系统各种传递对准方法讨论

 本文按对准基本原理将惯性导航系统各种传递对准方法分为两大类,一类可称为计算参数匹配法,它包括速度匹配和位置匹配;另一类可称为测量参数匹配法,它包括加速度匹配、姿态匹配和角速度匹配。文中详细讨论了这两类方法的性质,指出:计算参数匹配法类似静基座自对准和空间率对准,在载体无机动动作时对准时间较长。测量参数匹配法对准时间短,但受载体挠性变形的影响大。     

The autocorrelation of m-sequences over nonprime finitefields

Nonbinary m-sequences (maximal length sequences) for spread-spectrum communication systems that have a two-level autocorrelation are presented. The autocorrelation function of an m -sequence over the Galois field of q elements GF(q), where q=p^k, for p a prime and k an integer greater than 1, is developed and shown to be bilevel when the elements of GF(q) are expressed as elements of a vector space over the pth roots of unity