PCB材料与电源/地层谐振阻抗关系

为降低多层高速PCB(Printed Circuit Board)电源/地谐振阻抗,根据平行平面腔体谐振模型理论推导出PCB电源/地谐振阻抗、谐振频率、谐振品质因数与构成PCB板的导体材料和绝缘材料的电磁参数的之间的函数关系式,并根据此关系式得出了从PCB材料选取角度减小电源/地谐振阻抗的两种途径,即采用高磁导率、低电导率的导体材料代替普通导体材料;采用高介电常数和损耗正切的平面间绝缘体材料.随后PCB电源/地平行平面结构的全波仿真结果证实了这两种途径的有效性.      

基于机动时间的项目工期单因素不确定性分析

为了分析单个工序结束时间的变化对项目工期的敏感性,以总时差的概念及定理为基础,利用概率分析的原理及方法,确定了工序结束时间的变化在不同条件下的概率值,构建了项目工期单因素不确定性分析的指标评价体系,简要说明了指标体系中确定相关参数的思路与方法;然后,采用单因素敏感性分析法,重点分析了关键工序结束时间的变化对项目工期的敏感性,给出了不同关键工序结束时间的变化对项目工期的敏感性的判别方法,以及如何从被考虑的多个关键工序中找出需要重点考虑的对总工期敏感性最强的工序;最后,通过算例进行验证和说明.该评价体系在实践中有助于项目进度计划与控制,重点监督与控制对总工期敏感性强的工序,为项目工期的多因素不确定性分析奠定理论基础.      

电子战特种飞机电磁兼容预设计技术

为解决飞机电磁兼容传统设计方法的不足,提出并采用自顶向下、全机系统量化的电磁兼容预设计方法,在特种飞机系统方案论证阶段构建能量传输模型和系统受扰的关联矩阵,通过数值仿真、行为级仿真、等效推算、模拟测试、数据统计等手段,分析机载设备、火工品、燃油和人员的安全性,对全机的电磁兼容进行评估、指标量化分配和优化设计,实现全机系统良好的电磁兼容设计状态;能针对分系统指标的变动随时分析全机电磁兼容性的变化,也可为实现全机电磁兼容而调整分系统指标.该方法在全机系统定型前充分暴露可能出现的电磁兼容问题,并最大程度将其解决在系统设计阶段.该方法已应用于多个特种飞机型号的电磁兼容研制中,预设计成功率高,为解决型号研制中的电磁兼容问题提供了重要的技术支撑.      

FSK副载波光纤传输的灵敏度分析

在光纤传输系统中，副载波光纤传输是一种独特的传输方式，以ＭＩＬ－ＳＴＤ－１７７３年推荐的ＦＳＫ副载波光纤传输为例，对光接收机噪声及误率进行了分析，提出在色噪声情况下常规接收机的判决门限修正，为了简化计算起见，给出一种近似计算的方法，经计算，得到了副载波ＦＳＫ在不同接收机组态及码速率情况下的灵敏度曲线，并与常见的曼彻斯特码作了对比，分析了副载波光纤传输在不同场合时的性能。     

聚二醇类淬火介质CH－202的研究

介绍了聚二醇类淬火介质ＣＨ－２０２的合成、主要性能及冷却机理，并简单介绍了该介质在航空铝与钢制零件淬火方面的应用。     

Microstructure evolution of a hypereutectic Nb–Ti–Si–Cr–Al–Hf alloy processed by directional solidification

In this work, the Nb–14Si–24Ti–10Cr–2Al–2Hf–0.1Y alloy(at.%) was processed by the liquid–metal-cooled directional solidification(DS) at 1750 C with withdrawal rates of 1.2, 6,18 mm/min and post heat treatment(HT) at 1450 C for 10 h. The microstructures of the directionally solidified and heat treated samples were investigated. The results show that the microstructure of directionally solidified alloy mainly consists of petaloid Nbss+ Nb5Si3eutectics and Ti-rich Nbss+ Nb5Si3+ Cr2Nb eutectics. With the increase of withdrawal rate, the primary Nb5Si3is eliminated, Nbss+ Nb5Si3eutectic cells turn round and connected with the microstructure refinement and Nbss+ Nb5Si3+ Cr2Nb eutectics turn to a river-like morphology. After heat treatment,Nbss+ Nb5Si3+ Cr2Nb eutectics disappeared and petaloid Nbss+ Nb5Si3eutectics turn to a specific fiber-mesh structure gradually, which is promoted by higher withdrawal rates. Furthermore,both the volume fraction of Cr2Nb and the content of Cr in Nbssof Nbss+ Nb5Si3eutectics change regularly with the increase of withdrawal rate and heat treatment at 1450 C for 10 h.     

Grinding behavior and surface appearance of（TiC_p＋ TiB_w）/Ti-6Al-4V titanium matrix composites

（TiCp＋ TiBw）/Ti-6Al-4V titanium matrix composites（PTMCs） have broad application prospects in the aviation and nuclear field. However, it is a typical difficult-to-cut material due to high hardness of the reinforcements, high strength and low thermal conductivity of Ti-6Al-4V alloy matrix. Grinding experiments with vitrified CBN wheels were conducted to analyze comparatively the grinding performance of PTMCs and Ti-6Al-4V alloy. Grinding force and force ratios, specific grinding energy, grinding temperature, surface roughness, ground surface appearance were discussed. The results show that the normal grinding force and the force ratios of PTMCs are much larger than that of Ti-6Al-4V alloy. Low depth of cut and high workpiece speed are generally beneficial to achieve the precision ground surface for PTMCs. The hard reinforcements of PTMCs are mainly removed in the ductile mode during grinding. However, the removal phenomenon of the reinforcements due to brittle fracture still exists, which contributes to the lower specific grinding energy and grinding temperature of PTMCs than Ti-6Al-4V alloy.     

指点信标结合试飞研究

民用飞机航电系统复杂,试飞科目和架次繁多,为提高试飞效率,结合试飞是一个重要途径。深入研究了指点信标系统和FAA咨询通告(AC)对于指点信标建议的试飞方法,在此基础上,提出了一种新的结合试飞方案——从飞机正常着陆中获取需要的参数作为指点信标符合性分析,相比于独立的指点信标试飞,这样不仅获得的数据量大,试飞效率也更高。     

DSO高性能显示控制系统设计

为满足数字存储示波器(DSO)大流量实时数据显示的需要,本文设计了一种以A ltera FPGA和T I C 5000DSP为核心的高性能液晶屏(LCD)显示控制系统。该系统只需主机直接提供采样数据和少量控制字,便可自动生成显示所需的各种菜单,完成对采样数据的处理,产生输出波形,并驱动LCD以恒定刷屏速率进行显示。系统减轻了主机负担,实现了LCD高速数据更新,提供了灵活的接口电路,并在测试中获得了每秒80帧的波形更新速率。