基于接收机跟踪性能的GPS压制干扰效果分析

随着抗干扰技术的发展,为了更准确地分析P(Y)码与C/A码GPS接收机的压制干扰效果,在分析现有GPS接收机压制干扰效果研究方法和评价指标的基础上,提出了一种基于接收机跟踪性能的可用于同时分析P(Y)码与C/A码GPS接收机压制干扰效果的方法.与传统的压制干扰效果研究方法相比,该方法更接近于实际试验结果.     

Henry Nock,Walter Dick and Charles Lennox,The Duke of Richmond,and the Journey to the Final Designs of the Nock screwless lock

This paper introduces the Duke of Richmond’s Muskets and their precursors as made by Henry Nock and others. It particularly explores the development pathway for Nock’s Screwless locks by examining the production variants, the known prototype and experimental versions and in particular the prototype breech loading muskets. There are now known to be three breech loading prototypes, two very similar guns with locks marked by Henry Nock and a similar gun that appears by comparison to locks known to be by Walter Dick to have a lock made by Dick. This examination indicates that Nock was likely to have been instructed to make the production lock smaller than the prototype and that a key design step that enabled this was the use of a small double-ended mainspring linked to the cock and actuating the steel (frizzen) via a lever as developed by Dick.     

信息化条件下基于大数据的后装一体化保障构想

由于契约的不完全性、专用性资产的存在,导致民企参军的谈判过程中,一方可能利用另一方因专用性资产投资的锁定效应,而采取机会主义行为将另一方套牢,攫取可占用专用性准租金。这种套牢风险不是单向的,而是双向的,双向套牢风险的存在不仅会降低军品科研生产项目建设质量,而且还会严重挫伤民营企业承担军品科研生产任务的积极性。为有效防范双向套牢风险,本文将从博弈论的角度,建立民营企业与军队采办部门的期望收益与专用性资产投资的函数关系和博弈矩阵,分阶段讨论民营企业与军队采办部门所面临的套牢风险大小及各自的最佳行为选择。以降低民企参军面临的套牢风险,引导更多优势民营企业进入军品科研生产与维修领域,推动军民融合的深度发展。     

基于CompactPCI的共享内存通信研究与实现

文中介绍了CompactPCI总线的地址映射机制,分析了基于VxMP实现多处理机间通信可能存在的问题,重点讨论了利用互访共享内存实现通信的方法,给出了测试结果,并作了理论分析。     

一种基于VXI总线有精确时延的方波发生器

时钟源是为一个系统提供时间基准的单元设备,它的准确程度直接影响整个电路工作的稳定性。基于VXI总线的精密时钟源模块可以为系统提供任意分频的时钟信号以及精确的相位延时,其延时最小时基为6 25ns,并可精细调节,用锁相环实现的这种相位延时精度高,性能稳定,大大提高了整个电路系统的工作效率。     

相位非线性畸变对GPS伪距测量的影响

基于直接序列扩频体制的伪距测量在卫星导航、雷达、航天测控、深空探测等领域获得了广泛应用.射频链路、电缆多径等引入的相位非线性畸变会对扩频信号的传输时延产生影响,进而影响延迟锁定环(DLL)的伪距测量结果.传统群时延的定义难以描述一定带宽内的相位畸变,也难以与扩频信号时延建立对应关系.在对相频曲线进行Taylor展开的基础上给出了群时延的新定义,利用零阶群时延、线性群时延和抛物线群时延等来描述相位畸变,并定量研究各阶群时延对DLL伪距测量的影响.所得结论表明抛物线(二阶)群时延对伪距测量的影响最大.     

某火箭炮高低行军固定器设计与仿真分析

根据某火箭炮的特点和行军固定器的设计要求,对比各种锁紧方式的优缺点,为其设计了机械式高低行军固定器,通过计算初步确定了楔形块和驻钩上斜面的倾角、回复弹簧的刚度系数等主要参数。在Adams中仿真行军固定器的锁紧、解锁和受冲击载荷作用的过程,检验其是否能满足使用要求。根据动力学仿真结果得到的载荷数据,在Abaqus中对行军固定器的关键部件支臂进行有限元分析。仿真和计算结果表明:行军固定器可实现自动锁紧,解锁过程所需的手柄力符合设计要求,在冲击载荷作用下锁紧可靠,支臂的刚强度满足要求。     

Research and development of training pistols for laser shooting simulation system

Firearm shooting simulators are effective means for training the personnel in armed forces, police and shooting athletes. Shooter–weapon is a complex biomechanical system, therefore the best training quality is achieved when the process of a weapon shot is reconstructed in a training simulator and its training weapon mimics the (feeling) perception of the real weapon usage. Dynamics of motions of a handgun simulator held in the hand of a shooter by its grip during the shot is analysed theoretically and experimentally. Breech lock mechanism of the simulator is actuated pneumatically by supplying compressed air in pulses from external pressure source. Analysis of the obtained simulation results and experimentally recorded motion parameters of the training weapon body reveals that application of pneumatic drives is a reasonable option to simulate recoil perception of a pistol.     

鹤管气阻与泵汽蚀分析

鹤管气阻与泵汽蚀所指的对象不同,但两者具有相同的物理意义,都是指当液体介质的绝对压力小于其实时饱和蒸气压时所体现的物理现象。阐述了鹤管气阻的原因及目前解决的措施,分析了离心泵汽蚀方程的物理意义。根据能量平衡方程,推导出吸入系统管道不发生气阻的安装高度方程,并与泵不发生汽蚀的安装高度方程进行了对比分析。最后得出结论,要保证离心泵正常工作,必须同时满足吸入系统工艺管道安装高度要求以及泵安装高度要求。     

Design and analysis of a scheme for the naval gun test shell entering the bore

The test shell without projectile belt is widely used in the teaching, inspection and maintenance of modern automatic naval guns. In order to ensure the normal work of each mechanism, it is very important to design the buffer and limit of the test shell during the process of entering the bore. Taking a certain type of medium caliber naval gun as the research object, the design of colloidal fluid damper and cartridge lock was proposed to ensure the reliability of entering the bore and closing the breechblock. By combining the simulation methods of computational fluid dynamics (CFD) and multibody system dy-namic (MBD), it was analyzed whether the structural design can meet the engineering requirements. The research results show that the colloidal fluid damper can dissipate a large amount of kinetic energy of the shell, and the cartridge lock can limit the rebound movement. The combination of the two ensures the smooth process of closing the breechblock. The research provides a design method for the process of the test shell entering the bore, and provides theoretical support for the feasibility of the method.