一种用于RM不稳定性研究的竖直环形激波管的设计与验证

设计并加工了一套竖直环形同轴无膜激波管,可用于环形汇聚激波诱导下的Richtmyer-Meshkov不稳定性实验研究。与前人工作相比,本文在流体界面的形成以及流场的观测方法上做了较大的改进。通过实验和数值方法,对该竖直激波管产生的环形柱状汇聚激波的参数进行测量和分析,验证了同轴激波管形成柱状汇聚激波方法的可行性和可靠性。在界面形成方面,采用细丝约束肥皂膜技术形成正八边形气体界面,并利用数值方法考察了细丝对界面发展的影响。结果表明在界面发展的前期,细丝的影响几乎可以忽略。利用连续激光片光结合高速摄影相机对流场进行观测,获得了正八边形air/SF6气体界面在环形汇聚激波及其反射激波冲击下的演化过程,并与数值结果进行了对比,获得了较好的一致性,进一步验证了汇聚激波的对称性以及细丝约束肥皂膜技术用于形成多边形气体界面的可靠性。     

基于双通道外部总线接口的LCD显示设计

以带有双通道外部总线接口的AT91SAM9263芯片为例,提出一种新的利用双通道外部总线接口实现LCD显示的方法。给出硬件电路、bootloader和Linux kernel等的具体实现,并测试系统性能,说明了双通道外部总线接口在提升系统性能方面的重要作用。     

自动换档频率计

该文介绍了利用AT89C2051设计的自动换档频率计，该频率计具有精度高，测频范围较宽，自动换档，价格低等优点，具有很高的性能价格比。     

基于ARM-Linux平台的机载数据采集记录装置设计

为适应现代飞行试验的要求,介绍了一种自主研发的基于ARM-Linux平台设计的机载数据采集记录装置,该装置能实时地获取飞机飞行时的各种参数,为飞机试飞的状况分析提供基本的数据和信息,并详细地介绍了该装置的软硬件构成。     

Corrosion Resistance of Ni-P Composite Coating on Mg Alloy： Critical Role of the Intermediate Phosphate Conversion Coating Layer for Suppressing Galvanic Couple Formation

Electroless nickel (EN) plating can give rise to the severe galvanic corrosion of the magnesium (Mg) alloy matrix, owing to its nobler electrochemical potential than Mg alloy. To hinder the formation of galvanic couple, an intermediate phosphate conversion coating (PCC) layer is introduced between the EN layer and the Mg alloy matrix. Since the ceramic-like PCC layer cannot be catalyzed, a low-cost Ag-activation technique is used to process the PCC layer before electroless plating. The cross-section morphology and element distribution of the PCC-EN composite coating indicate that the PCC intermediate layer can effectively separate the Mg alloy from the EN layer. Moreover, the results of electrochemical tests suggest that the PCC-EN composite coating has a better corrosion resistance in comparison with the EN coating and AZ91D Mg alloy.     

基于AT89S52的移动机器人控制系统设计

本文介绍了三轮结构型移动机器人的运动控制系统的结构和工作原理,采用分级式控制的方法,以AT89S52作为底层控制系统的核心控制器,介绍了系统的硬件和软件设计。经过实验测试,能够满足移动机器人运动控制要求。     

基于单片机的LXI总线接口模块设计

文中设计了一款基于单片机的网络接口卡,用于仪器间的总线通讯。设计采用常见的RTL8019AS为网络控制器,它可以提供一个即插即用的适配器方案。主控电路的设计采用MCU／DSP＋前后台应用软件方式。文章从硬件和软件两个方面详细叙述了设计思路与过程。     

Hot Tearing Behavior of Mg-Gd-Y-X Alloys

Mg-Gd-Y-Zr alloy castings are widely used in the aerospace field owing to their high strength and excellent creep resistance. The castability of these alloys is also an important consideration for engineering application. Thus， the hot tearing susceptibilities (HTSs) of Mg-10Gd-1Y-1Zn-0.5Zr (VW91) alloy and Mg-10Gd-2Y-1Zn-0.5Zr (VW92) alloy are investigated with a constrained rod casting (CRC) mold. The microstructures and fracture surface are characterized by optical microscope and scanning electron microscope. The results unveil that the HTS of VW92 alloy is lower than that of VW91 alloy. The microstructures indicate that obvious tears can be observed in VW91 alloy， while the tears in VW92 alloy are tiny. The tear feeding and healing by eutectic are also observed in VW91 and VW92 alloys. Therefore， the lower hot tearing susceptibility of VW92 alloy is mainly attributed to the high amount of eutectic which feeds and heals tears. Besides， the effects of the coefficient of thermal expansion (CTE) and the fluidity of VW91 and VW92 alloys on their HTSs are discussed.