沉积含Si过渡层对于不锈钢上沉积的DLC薄膜的性能影响

本文介绍了采用RF-PECVD法在3Cr13不锈钢基体圆片上沉积制备类金刚石多层膜,其内层薄膜为掺Si的过渡层,外层为不同厚度的在50～1000 nm之间的类金刚石薄膜（DLC）。实验结果表明沉积过渡层可以有效提高薄膜与基体的结合力。类金刚石薄膜的摩擦系数和薄膜在摩擦过程中的损坏情况都与外层薄膜的厚度有关。     

基于视觉生理的民机应急出口标志字体研究

民用飞机客舱应急出口标志为乘客在紧急撤离时提供指引作用,但究竟选用哪种字体更为合适却没有统一的规定,从视觉生理的角度对比分析了几种常用的印刷字体,从而选出最佳的字体。     

弧形燕尾榫结构设计及形状优化

为了设计弧形燕尾榫结构,对弧形燕尾型榫及叶片/榫头连接部位的三角过渡段进行研究,设计一种新的叶根型线.在上述工作基础上,建立了叶根型线与榫头顶面的尺寸约束关系,利用ANSYS软件建立叶片/榫头参数化模型,并开展榫头结构及叶根型线的优化设计,结果表明优化后的新结构叶背处的应力为827.11MPa,比原结构下降6.51%;...     

空间近程高速相对运动方程的状态转移矩阵

分析了空间近程高速相对运动的特点,建立了描述近程高速相对运动的线性微分方程组,并给出了状态转移矩阵与解析解。仿真结果表明:对于HEO-GEO近程高速相对运动,所建方程的相对距离计算误差仅为16 cm,不足Hill方程计算误差的15%。所给出的状态转移矩阵对于实现空间目标拦截等任务的实时高精度相对导航和制导算法具有一定的应用价值。     

Improved local amplification factor transport equation for stationary crossflow instability in subsonic and transonic flows

Transition prediction is a hot research topic of fluid mechanics. For subsonic and transonic aerodynamic flows, e^N method based on Linear Stability Theory (LST) is usually adopted reliably to predict transition. In 2013, Coder and Maughmer established a transport equation for Tollmien-Schlichting (T-S) instability so that the e^N method can be applied to general Reynolds-Average-Navier-Stokes (RANS) solvers conveniently. However, this equation focuses on T-S instability, and is invalid for crossflow instability induced transition which plays a crucial role in flow instability of three-dimensional boundary layers. Subsequently, a transport equation for crossflow instability was developed in 2016, which is restricted to wing-like geometries. Then, in 2019, this model was extended to arbitrarily shaped geometries based on local variables. However, there are too many tedious functions and parameters in this version, and it can only be used for incompressible flows. Hence, in this paper, after a large amount of LST analyses and parameter optimization, an improved version for subsonic and transonic boundary layers is built. The present improved model is more robust and more concise, and it can be applied widely in aeronautical flows, which has great engineering application value and significance. An extensive validation study for this improved transition model will be performed.     

适于RTM 的氰酸酯树脂制备及性能

采用流变仪、DSC、DMA、TGA和介电性能测试方法研究了用于RTM工艺的改性氰酸酯树脂的流变、固化反应特性、耐热性和介电性能。结果表明:改性氰酸酯树脂在90~170℃温度范围内黏度500 m Pa·s,90℃时黏度为280 m Pa·s,适用期10 h;固化反应活化能为39.5 k J/mol,反应级数为0.89;树脂固化后玻璃化转变温度为294℃,热分解温度为420℃;9.375 GHz的介电常数为2.85,损耗角正切5×10-3。     

砷化镓异质外延薄膜的近红外光致发光研究

本文通过在硅衬底上用ＭＯＣＶＤ方法生长的砷化镓外延薄膜的变激发强度的近红外光致发光，研究了在液氮温度下峰值为１．１３与１．０４ｅＶ两个发光带的发光特性。     

飞行控制系统CAN总线优化方法研究

控制器局域网(CAN)作为一种可有效支持分布式控制和实时控制的多主串行通信总线,因具有纠错能力强、电磁兼容性好,实时性好、以及成本低等特点,正逐渐在航空航天领域得到广泛应用.本文从对总线性能影响显著的总线位定时入手,深入分析了通信波特率、位周期的取样位置等参数对网络通信性能的影响;并采用该方法对某型号CAN总线应用进行了优化,通过实时监听记录,检测数据传输波形,捕捉错误帧等手段,结合眼图分析,解决了错误帧的问题,并给出了结论.     

Prediction of Boundary Layer Transition Based on Modeling of Laminar Fluctuations Using RANS Approach

This article presents a linear eddy-viscosity turbulence model for predicting bypass and natural transition in boundary layers by using Reynolds-averaged Navier-Stokes (RANS) equations. The model includes three transport equations, separately, to compute laminar kinetic energy, turbulent kinetic energy, and dissipation rate in a flow field. It needs neither correlations of intermittency factors nor knowledge of the transition onset. Two transition tests are carried out: flat plate boundary layer under zero ...