An efficient and modular modeling for launch dynamics of tubed rockets on a moving launcher

This paper develops a modular modeling and efficient formulation of launch dynamics with marching fire (LDMF) using a mixed formulation of the transfer matrix method for multibody systems (MSTMM) and Newton-Euler formulation. Taking a ground-borne multiple launch rocket systems (MLRS), the focus is on the launching subsystem comprising the rocket, flexible tube, and tube tail. The launching subsystem is treated as a coupled rigid-flexible multibody system, where the rocket and tube tail are treated as rigid bodies while the flexible tube as a beam with large motion. Firstly, the tube and tube tail can be elegantly handled by the MSTMM, a computationally efficient order-N formulation. Then, the equation of motion of the in-bore rocket with relative kinematics w.r.t. the tube using the Newton-Euler method is derived. Finally, the rocket, tube, and tube tail dynamics are coupled, yielding the equation of motion of the launching subsystem that can be regarded as a building block and further integrated with other subsystems. The deduced dynamics equation of the launching subsystem is not limited to ground-borne MLRS but also fits for tanks, self-propelled artilleries, and other air-borne and naval-borne weapons undergoing large motion. Numerical simulation results of LDMF are given and partially verified by the experiment.     

基于改进鲸鱼优化算法的武器目标分配

针对鲸鱼优化算法寻优搜索精度低、易早熟问题,提出一种改进的鲸鱼优化算法,并将其用于对多约束的武器目标分配模型的求解.在鲸鱼寻找猎物阶段,通过引入差分进化算法的变异策略改善鲸鱼位置更新方式,提高算法全局寻优能力;引入自适应变量调整鲸鱼位置更新过程,平衡算法的全局探索和局部寻优能力,并在迭代过程中筛选并保留优秀个体;通过仿真结果表明,改进算法与其他算法相比,提高了武器目标分配收益和分配速度.     

一种弹道外测数据的野值处理方法

为抑制弹道外测数据中异常值的影响,设计了一种基于最小二乘趋势项建模与一阶差分还原的联合野值处理方法.该方法基于最小二乘原理建立了外测数据趋势项多项式的一般模型;利用一阶差分处理化斑点型野值为孤立型野值,在简化野值类型的同时又降低了野值的处理难度;最后引入肖维涅准则进行野值检验剔除,并积分还原得到便于后续分析的外测数据.仿真算例结果对比表明,该方法简便易行,在不破坏原始数据有用信息前提下,可抑制复杂类型野值的影响,取得较好的处理效果.     

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.     

正交频分复用水声通信自适应调制算法

分析预估信道长度对信道估计算法的影响规律,提出利用水声通信均衡恢复信号统计量对信道估计质量评估的方法。通过信道长度自适应修正机制,实现对未知水声信道的高精度估计。针对水声信道造成的正交频分复用子载波特性差异,基于信道估计结果,提出在码元总速率、能量约束条件下,各个正交频分复用子载波速率、功率优化分配的自适应调制算法。与传统的等功率、速率分配算法相比,新算法能够显著提升水声通信系统的误码率性能,通过仿真和实地试验,验证了研究内容的有效性。     

火控系统BIT设计与实现

采用层级BIT设计架构,建立了系统级和模块级BIT系统设计模型。设计了PBIT、CBIT、IBIT测试项探测函数、恢复函数等节点属性的统一数据结构。引入故障树理论设计了PBIT、CBIT、IBIT通用自动遍历故障树测试算法,可以实现多种火控系统的"自下而上"的节点测试和"自上而下"的故障诊断。在某火控系统预研项目的应用表明,本BIT系统的设计方案合理可行,易于维护,可显著提高通用火控系统的测试性和可靠性。     

基于HHT军用电源逆变器电力谐波检测分析

电能逆变器是军用电源系统的核心,为提高军用电源输出电压电力谐波分析效果,提出改进型希尔伯特-黄变换(HHT)方法的检测分析方法,并设计基于LabVIEW平台的电压谐波检测和分析装置。在研究双闭环控制策略的基础上,针对模态混叠问题,先使用数字滤波器对输出电压信号进行预处理,再进行改进HHT分析,得到输出电压谐波分量的幅频分布,并利用MATLAB对军用电源逆变器模型进行仿真。结果表明该方法可以对军用电源变换器输出谐波分量实时检测和分析,计算精度高,分析效果好,为下一步的谐波抑制方法研究提供有力支持。     

功率循环下IGBT模块电热参数变化规律分析

为了分析IGBT模块老化过程中电热参数的变化规律,对IGBT模块进行了功率循环加速老化试验,并基于单脉冲测试方法在加速老化试验进程中每间隔1 000次功率循环,测取一次IGBT的结温、集电极电流与饱和压降三维关系曲面、开关能耗、热阻抗以及瞬态热阻抗曲线。IGBT模块老化失效时,其饱和压降、开通能耗、关断能耗以及热阻较其初始值分别增大了3.92%、12.05%、18.87%和22.65%,试验结果表明随着IGBT模块功率循环次数的增多,相同工作条件下IGBT饱和压降的增幅逐渐加大,而饱和压降、结温和集电极电流三者间的内在关系没有明显变化;IGBT瞬态热阻抗曲线暂态部分几乎不变,稳态部分向上移动的幅度逐渐加大;测取的IGBT模块电热参数中饱和压降增幅最小,开关能耗增幅较大,模块热阻的增幅最为明显。     

战术移动自组织网络路由方法

战术移动自组织网络(Mobile Ad Hoc Network,MANET)作为网络中心战的重要组成,有望解决未来战场上传统作战力量与新型无人作战平台之间高效组网通信问题。战术MANET作为MANET在战场环境下的应用,可在基础设施缺乏或遭破坏的地域快速展开,具有节点自由出入、移动性高、抗毁伤性强等特点。综述了战术MANET路由协议和仿真方法,对研究方法和面临的挑战作了简要评述。     

新疆少数民族双语教师信息化教学能力现状及培训策略研究

如何提高新疆少数民族双语教师利用信息技术开展教学的能力,是双语教育的一个难题.国家和自治区投入了大量的时间和精力来提升少数民族双语教师的信息化教学能力,但始终没有收到显著效果.本研究采用调查研究法,对参加石河子大学“一年制”少数民族双语培训的教师进行问卷调查和访谈,通过研究新疆少数民族双语教师的信息化教学能力现状及存在的问题,提出针对少数民族双语教师的信息技术培训策略,为新疆少数民族地区的教育信息化建设以及少数民族双语教师的专业发展提供参考.