基于两坐标雷达与红外传感器的融合跟踪

针对两坐标雷达与红外传感器的融合跟踪问题,提出一套基于航迹关联事件的后验概率最大化准则和"最近邻"思想的状态信息相关与融合估计的一体化实现方法,克服了两种传感器观测数据不完整给融合处理带来的困难,通过充分利用雷达的航迹,点迹和历史信息,融合高精度的红外测角和雷达测距信息,改善系统的跟踪能力.最后的仿真实验表明了该方法的有效性.     

数字波束形成技术(DBF)在雷达中的应用

数字波束形成技术是天线波束形成原理与数字信号处理技术相结合的产物,其广泛应用于阵列信号处理领域。由于电磁工作环境的恶化和大量射频干扰的存在,在极低的信干噪比(SINR)条件下进行目标检测和信息提取十分困难。对于阵列系统,往往采用自适应数字波束形成(ADBF)技术,来抑制强干扰和方向性干扰对有用信号的影响。介绍了数字波束形成器的基本原理及其DSP的实现结构。     

反辐射无人机在电子战中的应用及其效能分析

简要讨论了反辐射无人机系统的组成和两种典型的反辐射无人机,指出了其在电子战中的应用。并针对某型反辐射无人机的系统能力,即命中概率和毁伤概率进行了理论分析和计算。     

An EOQ model with multiple suppliers and random capacity

We consider an EOQ model with multiple suppliers that have random capacities, which leads to uncertain yield in orders. A given order is fully received from a supplier if the order quantity is less than the supplier's capacity; otherwise, the quantity received is equal to the available capacity. The optimal order quantities for the suppliers can be obtained as the unique solution of an implicit set of equations in which the expected unsatisfied order is the same for each supplier. Further characterizations and properties are obtained for the uniform and exponential capacity cases with discussions on the issues related to diversification among suppliers. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

软件集群路由器体系结构的研究

分析了集群路由器的研究现状,而后提出了软件集群路由器的两个参考模型:SCR-RM(software-based cluster router reference model)和PCR-RM(parallel cluster routing reference model),给出两个参考模型的具体描述。这两个参考模型将为集群路由器的后续研究提供参照系统、实验系统和IP流处理场景。     

MIMO信道的三维互相关模型及其相关特性分析

针对频率选择性衰落MIMO移动信道,建立三维(3D)纯随机模型,并推导出3D MIMO信道模型的联合空时频相关函数。新的3D模型统一了现有的多种信道模型,新的联合空时相关函数综合考虑了信道收发两端的多普勒扩展、信号到达方向与离开方向的3D非均匀扩展与两端天线阵的配置。最后基于新的相关函数,分析了非均匀角度扩展参数以及阵元配置参数的变化对MIMO信道相关特性的影响。     

人机共融的远程态势智能感知系统

针对人与远程无人设备协同精准配合的迫切需求,以机器人操作系统为基础构建了一种人机共融的远程态势感知系统,并开展了实验与分析。该系统以视觉定位技术为基础,以人机感知共融为切入点,通过实时三维场景重建技术与场景一致性融合方法,将无人设备探测到的环境及目标信息进行三维重构,并通过增强现实设备进行显示,与人的视觉信息进行一致性融合,实现无GPS条件下远程无人设备与人所佩戴的增强现实设备之间的协同定位。实验结果表明,系统在近距离时具有较好的人机协同定位准确度,定位精度随着距离的增加而逐渐降低。所构建的系统使无人设备成为人眼的延伸,在不干扰人员正常行动的情况下实现了穿障碍、跨视距的感知能力,在未来信息化作战中可发挥重要作用。     

Research on the intermediate phase of 40CrMnSiB steel shell under different heat treatments

In this study, 40CrMnSiB steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A mid-explosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40CrMnSiB steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thick-ness and the number of the circumferential divisions. The results show that as the tempering temper-ature was increased from 350 to 600 ℃, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface.     

Static and free vibration analyses of functionally graded porous variable-thickness plates using an edge-based smoothed finite element method

The main purpose of this paper is to present numerical results of static bending and free vibration of functionally graded porous (FGP) variable-thickness plates by using an edge-based smoothed finite element method (ES-FEM) associate with the mixed interpolation of tensorial components technique for the three-node triangular element (MITC3), so-called ES-MITC3. This ES-MITC3 element is performed to eliminate the shear locking problem and to enhance the accuracy of the existing MITC3 element. In the ES-MITC3 element, the stiffness matrices are obtained by using the strain smoothing technique over the smoothing domains formed by two adjacent MITC3 triangular elements sharing an edge. Materials of the plate are FGP with a power-law index (k) and maximum porosity distributions (Ω) in the forms of cosine functions. The influences of some geometric parameters, material properties on static bending, and natural frequency of the FGP variable-thickness plates are examined in detail.     

Formation and characterization of core-shell CL-20/TNT composite prepared by spray-drying technique

The core-shell 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/2,4,6-Trinitrotoluene (CL-20/TNT) composite was prepared by spray-drying method in which sensitive high energy explosive (CL-20) was coated with insensitive explosive (TNT). The structure and properties of different formulations of CL-20/TNT composite and CL-20/TNT mixture were characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Laser particle size analyzer, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), impact sensitivity test and detonation performance. The results of SEM, TEM, XPS and XRD show that ϵ-CL-20 particles are coated by TNT. When the ratio of CL-20/TNT is 75/25, core-shell structure is well formed, and thickness of the shell is about 20–30 nm. And the analysis of heat and impact show that with the increase of TNT content, the TNT coating on the core-shell composite material can not only catalyze the thermal decomposition of core material (CL-20), but also greatly reduce the impact sensitivity. Compared with the CL-20/TNT mixture (75/25) at the same ratio, the characteristic drop height of core-shell CL-20/TNT composite (75/25) increased by 47.6% and the TNT coating can accelerate the nuclear decomposition in the CL-20/TNT composites. Therefore, the preparation of the core-shell composites can be regarded as a unique means, by which the composites are characterized by controllable decomposition rate, high energy and excellent mechanical sensitivity and could be applied to propellants and other fields.