HP8350B扫频仪射频插件单元故障修理三例

针对HP8350B系列微波扫频仪射频插件单元的三例典型故障。介绍了其修理方法，同时就该类微波测量仪器在修理过程中应该注意的几个问题阐述了作者的意见。     

基于ArcGIS的公路沿线三维地形的建立和应用分析

以勉宁高速公路为例，在1：2000的公路沿线地形平面图的基础上，利用AutoCAD和R2V软件对其进行预处理，然后在ArcGIS中建立高精度的DEM，通过DEM和公路沿线平面图的叠加，生成公路沿线单个三维地形，建立Oracle数据库存储二维和三维地形数据，并对其中三维数据进行了缓冲区、面积和体积计算等三维应用分析。     

现代电视中音响技术的应用

本文介绍了电视机中伴音系统的发展,从传统的伴音系统发展成“双伴音/立体声”方式,出现了丽音系统,形成了同保真立体声效果。然后又引入了环绕声技术,以及全数字处理方式,达到了真正的音响效果。文中给出了实现其功能的典型电路,以及今后的伴音发展趋势。     

一类中立型泛函微分大系统的稳定性

本文考查了一类中立型泛函微分大系统，得出了平凡解的稳定性、渐近稳定性，指数稳定性等价定理。     

弓高弦长法测量圆直径的研究

弓高弦长法测圆直径的一个重要问题，是如何选取最佳测量点。本文从误差的传递着手，严密推证了弓高及弦长测量的标准差取不同值时最佳测量点的位置。     

实际检定工作中重复性引起不确定度的计算

论述采用合并样本标准差和B类不确定度评定方法计算重复性引起的不确定度，使可以在符合检定规将规定的较少测量次数中得到比较可靠的标准不确定度．     

220B协议中网络接入控制的分析与研究

文章叙述了M IL-STD-188-220B协议的网络接入控制过程,对220B协议中的5种网络接入控制技术算法(R-NAD,P-NAD,H-NAD,RE-NAD,DAP-NAD)做了详细的介绍,并将它们进行了比较,分析了各自的优缺点。     

GJB5000 A与DO-178 B／C的综合应用研究

针对软件研制单位目前存在的型号软件研制必须同时满足GJB5000 A与适航软件研制标准的要求,通过对GJB5000 A与DO-178 B／C的对比分析,提出一种将GJB5000 A与DO-178 B／C相互融合的方法,并对方法实际工程实践时应注意的问题进行了说明。     

Comparison between African equatorial station ground-based inferred vertical E × B drift,Jicamarca direct measured drift,and IRI model

The Incoherent Scatter Radar measurement over Jicamarca, together with the IRI model-2007 measurements were compared with ground-based digisonde inferred E × B drift over Ilorin in the African region during year of solar minima (F10.7 = 81). Seasonally, Ilorin pre-reversal enhancement (PRE) had peak drift velocities of 7.2, 3.7 and 7.9 m/s for March equinox, September equinox and December solstice respectively, while Jicamarca drifts indicated 13.0, 10.5 and 5.2 m/s; as well as the IRI model with 14.3, 8.4 and 0.7 m/s in similar order. PRE value was insignificant during June solstice. The PRE magnitude of the IRI-model during the equinoxes is twice the value obtained at Ilorin. The daytime E × B drift peaked over Ilorin 1–2 h earlier than both the modeled and Jicamarca observations. This could be due to the difference in sunset time at the conjugate points corresponding to the altitude of the observation. During the evening time PRE, the respective correlation coefficients (R) for Vz–F10.7 relation over Jicamarca, Ilorin and the modeled observations are −0.5559, 0.4796 and −0.4979. Similarly, the Vz–Ap relation exhibit excellent anti-correlation coefficient (R = −0.8637) for the IRI-model, −0.4827 over Jicamarca and 0.3479 for Ilorin. Annual mean drift velocities over Jicamarca, Ilorin and IRI model measurements respectively are 10, 5.6 and 10 m/s for the peak PRE observation; 15, 16 and 21 m/s for the daytime pre-sunrise peak values; and −21, −9 and −16 m/s for the nighttime downward reversals. The root-mean square (RMS) deviation between IRI-model and the Ilorin drift between 2000 and 0500 h is 4.37, 2.03, 3.71 and 2.42 m/s for March equinox, June solstice, September equinox and December solstice respectively. For Jicamarca–Ilorin drift relation, RMS deviation is 5.48, 2.30, 3.47 and 1.27 m/s in the same order respectively. Annual hmF2 inferred drift over Ilorin during daytime is higher by a factor of ≈2 and 3 at Jicamarca and IRI model measurements respectively; and by a factor of ≈5 for both during the night-time period. The limitations in using hmF2 to infer drifts are discussed.     

CFM56—5B发动机冬季运行燃油渗漏故障分析

介绍了7CFM56—5B发动机冬季运行中的燃油渗漏故障情况．根据冬季运行特点分析了燃油渗漏的原因，并提出相应的预防措施。