新体制导航信号下I/Q幅相不一致对接收机测距零值的影响分析

随着现代化导航信号带宽的增大,由于可以大幅降低采样率,复信号采样的优势日趋明显。由于存在I/Q幅相误差,复信号采样对导航接收机伪距测量造成了一定影响。改进了信道非理想与I/Q幅相误差共同影响BPSK/QPSK信号零值测量的分析模型;在该模型基础上,推导得到了任意I/Q误差和信道非理想特性影响BOC信号伪距零值的模型;探讨了二者在频域抗干扰应用场景下引起的零值变化;理论分析与软件接收机仿真结果高度吻合,误差在1.5×10^-4码片内,证明了分析模型的精确性。该分析方法可用于对高性能导航接收机信道特性进行事先约束及筛选,以确保干扰场景下的零值变化满足要求。     

微机上运行的多功能仿真语言GASP/PC

文中介绍了IRM-PC机上多功能仿真软件GASP/PC的开发,叙述了GASP/PC仿真语言的形成以及对于连续、离散和复合仿真模型的GASP/PC语言的结构与仿真方法。     

一种GPS数字中频信号软件模拟器的设计

为了给GPS系统中基于C/A码的卫星捕获及跟踪算法提供信号源,以GPS卫星发送信号模型为基础,分析了GP2010的工作原理,采用Matlab/Simulink以软件的方式模拟了GP2010的工作过程,完成了一种数字中频GPS信号软件模拟器的设计,最后采用一种基于C/A码的捕获和跟踪算法对软件模拟器进行了验证.仿真结果表明:设计的软件模拟器可以给基于C/A码的卫星捕获和跟踪算法提供信号源,与常规GPS信号模拟器相比,所设计的软件模拟器结构简单,设计灵活并可扩展,易于使用.     

Capacitated warehouse location model with risk pooling

In this article, we introduce the capacitated warehouse location model with risk pooling (CLMRP), which captures the interdependence between capacity issues and the inventory management at the warehouses. The CLMRP models a logistics system in which a single plant ships one type of product to a set of retailers, each with an uncertain demand. Warehouses serve as the direct intermediary between the plant and the retailers for the shipment of the product and also retain safety stock to provide appropriate service levels to the retailers. The CLMRP minimizes the sum of the fixed facility location, transportation, and inventory carrying costs. The model simultaneously determines warehouse locations, shipment sizes from the plant to the warehouses, the working inventory, and safety stock levels at the warehouses and the assignment of retailers to the warehouses. The costs at each warehouse exhibit initially economies of scale and then an exponential increase due to the capacity limitations. We show that this problem can be formulated as a nonlinear integer program in which the objective function is neither concave nor convex. A Lagrangian relaxation solution algorithm is proposed. The Lagrangian subproblem is also a nonlinear integer program. An efficient algorithm is developed for the linear relaxation of this subproblem. The Lagrangian relaxation algorithm provides near‐optimal solutions with reasonable computational requirements for large problem instances. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

准陶瓷Cf/SiC复合材料的制备

采用热重-差热(TG-DTA)、红外(IR)等分析测试手段,研究了聚碳硅烷(PCS)的裂解及化学转化过程,从理论上验证了先驱体聚碳硅烷(PCS)600℃裂解产物的准陶瓷特性.先驱体聚碳硅烷在600℃呈现一种半有机、半无机状态,其产物具有准陶瓷的特征,在大约750℃出现无机化转变高峰,固称其为准陶瓷.以碳布、准三维编织体、三维编织体为增强体,采用先驱体浸渍裂解(PIP)工艺在600℃制备了碳纤维增强碳化硅(Cf/SiC)准陶瓷基复合材料.结果表明,以三维编织体增强的准陶瓷Cf/SiC复合材料获得了较理想的结构、性能,所制备3D-Cf/SiC复合材料密度仅有1.27g/cm3,弯曲强度达到193.69MPa,室温拉伸强度为197.69MPa,600℃拉伸强度为167.33MPa.复合材料断口形貌分析表明,在低温600℃制备的准陶瓷Cf/SiC复合材料呈现明显的韧性断裂特征.     

A componentwise index of service measurement in multi‐component systems

In this paper we present a componentwise delay measure for estimating and improving the expected delays experienced by customers in a multi‐component inventory/assembly system. We show that this measure is easily computed. Further, in an environment where the performance of each of the item delays could be improved with investment, we present a solution that aims to minimize this measure and, in effect, minimizes the average waiting time experienced by customers. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 50: 2003     

利用MSC/DYTRAN程序仿真分析导弹战斗部立方体破片的侵彻威力

对反辐射导弹的破片杀伤战斗部中较为常见的立方体破片的 3种典型姿态侵彻 (尖端、棱边及正面侵彻 ) 4mm厚 94 5钢的侵彻过程进行仿真数值计算 .通过仿真计算 ,结合实验结果比较 ,得出结论 :不同初始侵彻姿态的立方体破片在侵彻过程中 ,由于旋转角速度的作用及稳定性的要求 ,破片的侵彻姿态将趋于正面侵彻 .不同姿态的侵彻 ,侵彻威力相差不大     

LabWindows／CVI环境下虚拟仪器驱动程序的开发

IVI仪器驱动程序消除了虚拟仪器系统中的测试冗余 ,提高了测试速度和测试系统中同类仪器的互换性。研究了IVI仪器驱动程序的结构、特点和工作机制 ,提出了在LabWindows/CVI环境下开发IVI仪器驱动程序的方法和步骤。     

Minimizing weighted earliness and tardiness penalties in single‐machine scheduling with idle time permitted

In this paper, a single‐machine scheduling problem with weighted earliness and tardiness penalties is considered. Idle time between two adjacent jobs is permitted and due dates of jobs could be unequal. The dominance rules are utilized to develop a relationship matrix, which allows a branch‐and‐bound algorithm to eliminate a high percentage of infeasible solutions. After combining this matrix with a branching strategy, a procedure to solve the problem is proposed. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 760–780, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10039     

一种从二维照片反求三维CAD模型的稳健方法

研究了从物体二维照片重构其三维CAD模型的算法。通过物体在不同方位的一组照片 ,选取一定数量的配准点 ,该算法能够计算出照相机的运动参数 ,进而得到物体表面的 3D几何信息及CAD模型。算法充分考虑到了CAD建模的可制造性约束 ,具有精确、稳健的特点 ,在逆向工程建模、计算机视觉、机器人领域有应用前景。