基于迎风型有限体积法的非结构化网格流场格心数据高质量体绘制方法

在计算流体力学领域,对复杂流场进行数值模拟时常用非结构化网格划分空间,并广泛采用迎风型有限体积法求解流场.该方法将数值解存储在非结构化网格单元(控制体)中心,产生格心数据,并假设物理量在相邻单元邻接面上形成"间断".然而,在可视化此类数据时,目前的重构方法破坏了间断约束,导致"流间断"信息丢失,严重制约了绘制质量.为此...     

极性基团对环氧树脂基体力学性能及吸水特性的影响

研究了CYD- 128/THPA/DMP- 30 (CTD)、TDE- 85/THPA/DMP- 30(TTD)、CYD- 128/IPDA(CI)与TDE- 85/IPDA (TI)4种环氧树脂基体浇铸体的拉伸、弯曲和耐海水性能,分析了树脂、固化剂类型和分子结构对树脂基体性能的影响.结果表明,使用相同固化剂时,TDE...     

舰艇信息系统基础设施发展回顾及展望

在分析三代舰艇信息系统基础设施发展过程的基础上,总结了其演进规律,从需求牵引、技术推动等角度分析展望了舰艇信息系统基础设施发展趋势,指出标准化仍是信息系统基础设施发展的内在动力,平台化将成为重点,进一步分析了现有设备可能存在的问题,给出了解决思路.     

Quasi-steady aerodynamic characteristics of Terminal Sensitive Bullets with short cylindrical portion

The aerodynamic characteristics are vital for short cylindrical Terminal Sensitive Bullets(TSB)with low aspect ratio,especially in terminal trajectory.Currently,there is little research in terms of the TSB and short cylinder with two free ends,and particularly in this trajectory,where the scanning angle β and roll angle α vary over a broad range between 0° and 180°.In this work,wind tunnel experiments are first conducted to learn the effects of Reynolds number and scanning angle on aerodynamic parameters for short cylinder with aspect ratio L/D = 1.Similar to infinite cylinder,for the short cylinder with two free ends,the drag crisis phenomenon still exists in the critical regime 1.7 × 105 ≤ Re ≤ 6.8 × 105.Then 3D simulations are performed to demonstrate the aerodynamic characteristics of short cylinder and TSB over a broad range of Re,L/D,α and β.The sensitivity analysis of time step and grid are presented as well.When β=0°,for short cylinder,the drag crisis phenomenon was also observed in the simulation,but not as obvious as in the wind tunnel test.In some attitudes,there is an obvious Kármán vortex in the wake of short cylinder and TSB.The correlation between time-averaged aerodynamic coefficients and L/D,Re,α&β is discussed.The vortex shedding frequency and shear layer behavior are obtained for quasi-steady and unsteady flow.Finally,the effect of end's shape on drag reduction and vortex shedding frequency is analyzed.     

冲激信号SAR反向投影成像方法I、Q 实现

本文在分析冲激信号成像特点的基础上，说明了线阵模型是解释冲激信号ＳＡＲ成像过程的有效方法，给出了冲激信号ＳＡＲ反向投影（ＢＰ）方法，针对系统实现问题，提出了对Ｉ、Ｑ两路信号分别积累，求模的ＢＰＩＱ法，并以计算机仿真及与常规的ＢＰ作比较，最后给出了一些有用的结论。     

一种有效的UWB-SAR成像方法

在简要总结大处理角ＵＷＢ－ＳＡＲ成像处理有关难点后，本文提出将波数域成像算法（Ω－Ｋ算法）应用于ＵＷＢ－ＳＡＲ成像处理；然后介绍了Ω－Ｋ算法的原理并对其中存在的Ｓｔｏｌｔ插值等问题进行了详细分析和深入探讨；最后结合所建立的ＵＷＢ－ＳＡＲ回波模型对Ω－Ｋ算法进行了仿真，研究表明这种成像方法具有较好的聚焦效果。     

线性调频基带数字产生的关键技术研究

介绍超宽带线性调频信号基带的数字产生方法及其实现技术。首先对线性调频信号的两种主要数字产生方法进行了简要阐述和比较，然后根据波形存储直读法提出了一种超宽带线性调频信号产生方案，分析了基带数字产生的主要关键技术，并进行了系统实现和测试。测试结果表明本文所提出的方法是可行的。     

高超声速飞行器多目标复杂约束滑翔弹道优化

针对气动热、过载、动压、控制量、航路点、禁飞区以及终端状态等复杂约束条件,提出高超声速飞行器多目标滑翔弹道优化方案。建立换极运动模型,简化部分约束条件的处理,并规避了传统运动模型的奇异问题;在此基础上,引入物理规划方法将多目标优化问题转换为反映设计者不同偏好的单目标优化问题;进一步基于分段Gauss伪谱方法将弹道单目标优化的最优控制问题转换为非线性规划问题进行求解。仿真结果表明,该方法获得的滑翔优化弹道能满足复杂约束要求,同时能够反映设计者的不同偏好。     

基于群体协同的驱护编队中近程防空的系统效能

针对中近程反导的具体要求,分析了典型的驱护编队反导模式下编群队形特点,研究了指挥舰与护卫舰的队形关联性,探讨了基于信息化作战模式的抗饱和攻击能力,建立了基于多目标优化的最保守与最乐观情况下的抗饱和攻击模型,得到舰艇编队协同防空的系统效能,对驱护编队防空反导指挥决策具有很强的参考价值。     

The interrelationship between defence spending,public expenditures and economic growth: evidence from China

This study examines the relationship between defence spending, other components of public spending and economic growth for the 1952–2012 period in China using Granger causality tests and generalised impulse response functions based on vector error correction models. The empirical results reveal two long-run equilibrium relationships among the variables and also show that defence spending inversely and unidirectionally Granger impacts economic growth. Furthermore, empirical findings point to a trade-off relationship between defence spending and public expenditures in China. From a policy maker’s perspective, the findings reported herein imply that a decrease in defence spending may stimulate economic growth.