串馈微带天线阵的增益和方向图计算

应用有耗传输线理论推出串馈微带阵各阵元电流的递推公式 ,给出了增益和方向图的计算曲线 ,与实验结果比对吻合良好 ,这表明串馈微带阵方向图计算必须计入微带线损耗才有可靠精度。还分析了微带天线阵的阵元数目变化与增益之间的关系 ,给出了计算曲线     

一种三维小基阵无源声测定向算法

无源声测定向是声学监视技术的重要研究内容。为了实现对低空运动目标的声学监视,提出了一种小基阵定向方法,并用线性回归分析原理导出了定向算法,对定向误差进行了理论分析和数值仿真。不仅适用于随机布阵的三维小基阵情况,也可应用到二维小基阵对声源的定向。理论分析和仿真表明,这种定向算法正确可行,且有较大的实用价值。     

Quantity discount pricing policies for heterogeneous retailers with price sensitive demand

Although quantity discount policies have been extensively analyzed, they are not well understood when there are many different buyers. This is especially the case when buyers face price‐sensitive demand. In this paper we study a supplier's optimal quantity discount policy for a group of independent and heterogeneous retailers, when each retailer faces a demand that is a decreasing function of its retail price. The problem is analyzed as a Stackelberg game whereby the supplier acts as the leader and buyers act as followers. We show that a common quantity discount policy that is designed according to buyers' individual cost and demand structures and their rational economic behavior is able to significantly stimulate demand, improve channel efficiency, and substantially increase profits for both the supplier and buyers. Furthermore, we show that the selection of all‐units or incremental quantity discount policies has no effect on the benefits that can be obtained from quantity discounts. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

扇区内插法设计虚拟均匀线列阵的研究

目前许多高分辨算法只适用于均匀线列阵的方位估计.在不规则阵列条件下,需将实际阵列等效为虚拟均匀线列阵.文中通过对基于扇区内插法设计虚拟均匀线列阵的研究,给出了设计的具体步骤,并提出一个简单且准确的虚拟线列阵阵元间隔的计算公式.     

无伞末敏子弹大攻角非线性空气动力和力矩模型

以无伞末敏子弹为背景,分析了描述大攻角飞行弹丸横向运动和角运动的运动变量,建立了大攻角情况下弹丸所受非线性空气动力和空气动力矩的模型,推导出了复数形式的弹丸横向运动与角运动方程。数值积分计算表明,弹丸在特定非线性空气动力和力矩作用下,能够形成所需形式的扫描运动,证明所建力学模型正确合理,可以用于无伞末敏子弹动力学特性的分析与计算。     

双圆阵模式空间二维解相干

提出一种相干信号二维波达方向(Direction of Arrival,DOA)估计算法——模式空间波达方向矩阵(Mode-Space DOA Matrix,MS-DOAM)法。算法基于双圆阵,利用模式空间转换将圆阵转换为虚拟双平行线阵,计算虚拟线阵阵元间的互相关信息,构造两个等效协方差矩阵,进而构造波达方向矩阵,对该波达方向矩阵特征分解,利用得到的特征值与特征矢量求得入射信号的仰角和方位角。算法无需二维搜索,实现估计参数自动配对。仿真结果表明,算法在低信噪比和短快拍条件下,估计误差低于虚拟空间平移算法。     

电化学极化状态对潜艇螺旋桨扰动电场模型的影响

潜艇服役期间涂层性能退变影响潜艇电场分布,以材料电化学极化状态为边界条件,应用边界元法建立潜艇涂层性能下降、涂层渗透腐蚀、涂层局部破损极化三种潜艇腐蚀静电场模型,从时域和频域特征对螺旋桨扰动电场模型进行分析。研究结果表明：电化学极化状态对螺旋桨扰动电场的电位信号特征及电场谐波频段影响显著。恒电位、线性极化、非线性极化三种边界条件下,螺旋桨以相同频率旋转扰动静电场时,各模型的频率成分占比差异明显。非线性边界条件下的扰动频率和2倍扰动频占比相差最大,线性边界条件下的扰动频率和2倍扰动频占比相差最小。三种边界条件下电场模型的3倍扰动频以上的谐波范围会发生改变,恒电位边界下模型谐波范围最小,非线性边界条件下谐波范围最大。     

低空复杂场景红外弱小目标快速精准检测

针对低空复杂场景下红外弱小动目标检测难度大、虚警率高等问题,面向探测系统中高帧频图像实时处理应用需求,提出基于全卷积网络的弱小目标精准检测方法和基于现场可编程逻辑门阵列(field programmable gate array, FPGA)的低时延并行处理方法。采用轻量化全卷积网络对红外图像中弱小目标进行空域检测,对相邻图像帧疑似目标进行时域轨迹关联以进一步降低虚警率。实验结果表明:上述方法相比于五种传统方法在检测率和虚警率性能方面均有显著提升,并在单片FPGA上完成100 Hz图像实时处理,处理时延低于1.8 ms,实现低空复杂场景弱小目标高精度高鲁棒快速实时检测。     

Three-dimensional coordinates test method with uncertain projectile proximity explosion position based on dynamic seven photoelectric detection screen

To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test method, which is made up of six plane detection screens and a flash photoelectric dynamic detection screen. The three-dimensional coordinates calculation model of the projectile proximity explosion position based on seven plane detection screens with dynamic characteristics is established. According to the relation of the dynamic seven photoelectric detection screen planes and the time values, the analytical function of the projectile proximity explosion position parameters under non-linear motion is derived. The projectile signal filtering method based on discrete wavelet transform is explored in this work. Additionally, the projectile signal recognition algorithm using an improved particle swarm is proposed. Based on the characteristics of the time duration and the signal peak error for the projectile passing through the detection screen, the signals attribution of the same projectile passing through six detection screens are analyzed for obtaining precise time values of the same projectile passing through the detection screens. On the basis of the projectile fuze proximity explosion test, the linear motion model and the proposed non-linear motion model are used to calculate and compare the same group of projectiles proximity explosion position parameters. The comparison of test results verifies that the proposed test method and calculation model in this work accurately obtain the actual projectile proximity explosion position parameters.     

数组越界软件测试系统的设计与实现

软件测试系统的研制是现阶段软件测试领域研究的一个热点.首先针对C/C 语言常见数组越界错误类型进行了分析,介绍了软件测试的一些基本概念,而后给出了软件测试系统设计,对系统设计的各个阶段进行了说明,并且给出了一种错误类型检查的算法设计,它在软件测试检测中具有通用性和代表性,最后给出了软件测试的实验结果.