军用飞机DSI数据采集系统的设计

由于军用飞机航空电子动态仿真与综合(DSI)系统所使用的固定采集周期的数据采集方法限定了采集速度,同时还影响到数据实时采集性能,针对该问题本文提出军用飞机DSI数据采集系统的设计方案.该方案的硬件结构基于MAX1308型AD转换器、DIO-144型采集卡,并设计了接口关系.系统的软件采用事件确认收发应答机制,并能确保在...     

波音767-300ER改装翼梢小翼的翼根翼型气动性能研究

基于波音767-300ER改装翼梢小翼的实际测量尺寸,建立了翼根翼型几何模型,并利用计算流体力学技术在波音767-300ER飞机巡航状态下分析了该翼型的气动性能,获得了在不同迎角时该翼型的压力和速度分布以及升阻比．为翼梢小翼的设计提供了一些理论依据。     

驻涡燃烧室凹腔温度变化规律及气量分配

通过对单双涡燃烧室进行热态试验研究,研究余气系数、进口气流参数对凹腔壁温分布的影响,并通过三维数值模拟对燃烧室及凹腔气流量进行计算,得到壁温分布规律,为燃烧室材料选择以及气量分配的后续优化做好铺垫.试验结果表明,单涡试验件的最高壁温出现在凹腔后壁面;燃烧室余气系数变化改变了双涡试验件最高壁温的位置;数值模拟结果比较准确的得到了驻涡燃烧室的气流量分布.     

高职院校图书馆读者到馆人数下降原因分析与对策

通过对部分高职院图书馆读者到馆情况的调查,分析图书馆读者到馆人数下降的原因,并提出相应对策。     

Evaluation and analysis on positioning performance of BDS/QZSS satellite navigation systems in Asian-Pacific region

By using the observation data and products of precise obit and clock offset from Multi-GNSS Experiment (MGEX) of the International GNSS Service (IGS) and GNSS Research Centre, Curtin University in this paper, the positioning performance of BDS/QZSS satellite navigation system has been analyzed and evaluated in aspects of the quantity of visible satellites, DOP value, multipath effect, signal-to-noise ratio, static PPP and kinematic PPP. The analysis results show that compared to BDS single system when the cutoff angle are 30°and 40°, the DOP value of BDS/QZSS combined system has decreased above 20%, and the quantity of visible satellites increased about 16–30% respectively, because of the improved spatial geometric configuration. The magnitude of satellite multipath effect of BDS system shows the trend of MEO?>?IGSO?>?GEO, which is consistent with that of QZSS satellite system, as the constellation structure of the two systems is similar. The variation tendencies of signal-to-noise ratio with respect to elevation angle of the two systems are almost the same at all frequencies, showing that at the same elevation angle the signal-to-noise ratio of MEO satellites is higher than that of IGSO satellites, as the higher obit is the lower transmitting power is obtained. For having a specially designed obit, the variation of signal-to-noise ratio of BDS system is more stable. However, the magnitude of signal-to-noise ratio of QZSS system appears the trend of frequency 3?>?frequency 2?>?frequency 1. The static PPP performance of the BDS/QZSS combination system has been improved more significantly than the BDS single system in E, N and U directions. When the cutoff angle are at 7°, 15° and 30°, the PPP accuracy is increased about 25–34% in U direction, 10–13% and 23–34% in E and N directions respectively. When the elevation angle is large (40°), compared to BDS single system at lower elevation angles (7° and 15°) the PPP accuracy of the BDS/QZSS combination system is improved above 30% in U direction. In kinematic PPP performance, compared to BDS single system, the accuracy, availability and reliability of the BDS/QZSS combination system has been improved too, especially at large elevation angles (30° and 40°), the kinematic PPP accuracy in E and U directions has been improved about 10–50%, and above 50% in U direction. It can be concluded that the combination with QZSS system can improve the positioning accuracy, reliability and stability of BDS system. In the future, with the improvement of the satellite construction of Japan’s QZSS system and the global networking of China’s BDS satellites, the QZSS satellites will contribute greatly to improve the positioning accuracy, reliability, availability and stability of GNSS systems in areas such as cities, mountains, densely-packed buildings and severely covered areas in Asian-Pacific region.     

B样条技术在RPM切片数据处理中的应用

首先介绍了RPM切片数据的处理问题,其次阐述了B样条的基本原理,最后研究了用三次B样条的反求技术对切片数据进行插值修补处理,并用弦高差方法对插值点进行取舍,生成最终的轮廓数据。     

加快中部地区对外开放的思考

对外开放是促进中部崛起的引擎.20世纪90年代以来,中部地区对外贸易快速增长,利用外资水平不断提高,对外经贸工作进展明显,投资环境得到改善,但还存在着开放度低、利用外资规模较小等问题.在对当前面临的开放环境与条件分析的基础上,提出了加快中部地区对外开放的对策建议.     

XY502胶粘剂最佳制样的选择与探讨

XY502胶粘剂的测试结果始终处于不稳定状态，通过大量的对比试验与研究，确定出XY502胶粘剂的最佳制样方法：混合甲乙组份2小时，打磨方式达到标准要求，同时在房间里配除湿机来把湿度固定在45％-55％范围内，胶接及停放温度对结果影响很大，必须把胶接及停放温度控制在25℃-30℃之间，这样XY502的测试结果才符合标准，以上方法才是最佳的制样方法。     

VLSI积木块布图设计中一种提高布通率的总体布线算法

论述了积木块布图设计中一种旨在提高布通率的总体布线算法。该算法以求解最小斯坦纳树算法为基础，采用总体布线资源动态调整，不断优化的方法，获得很高的布通率，该算法在ＶＬＳＩ－ＣＡＤ系统中应用取得很好的效果。     

空间拦截中只测量视线角速度的跟踪滤波器的可观性分析

建立了空间拦截中导弹与目标的相对运动方程。论述了卡尔曼滤波器的可观性准则，研究了跟踪滤波器的可观性，并分析了影响跟踪滤波器可观性的因素。数字仿真证实了理论的正确性。