基于试飞数据的涡轴发动机性能建模技术

为了实现军用涡轴发动机在装机状态下的虚拟预测试飞，通过罚函数法求解超定非线性方程组的最小二乘解，并采用回归分析对部件特性耦合因子进行曲线拟合，优化基准稳态模型，构建了某型涡轴发动机稳态性能计算模型；在此基础上，应用发动机加减速试飞数据，综合考虑部件容腔效应、转动部件的转子动力学和高温部件的传热效应，开发了涡轴发动机部件级过渡态性能计算模型。采用该模型对包线范围内不同工况的发动机稳态和过渡态工作过程进行了仿真预测，结果表明：与真实装机试验结果相比，发动机各工作参数的稳态预测精度在4.2%以内，过渡态预测精度在9.2%以内，满足工程精度要求。该模型能够满足虚拟预测试飞的技术需求，对涡轴发动机的设计、试飞和使用具有重要作用。     

Two-Dimensional Modal Curvature for Damage Detection in Plates

Mode shape has become a hotspot of vibration-based damage detection in plates.Two-dimensional(2D)modal curvature(MC2D),derived from mode shapes,is a prevailing physical quantity used to indicate damage.Unfortunately,the physical mechanism of MC2 Dfor characterizing damage in plates has not been clarified to date.In contrast,one-dimensional(1D)modal curvature(MC1D)has explicit physical mechanism to portray damage in beams.Unresolved physical mechanism of MC2 Dseverely hampers its applications for damage identification in plates.To address this deficiency,the clarification mechanism of MC2 Dis investigated to identify damage.With the clarified mechanism,numerical and experimental cases are used to demonstrate the effectiveness of MC2 Din detecting damage in plates.     

大数据分析过程中的降维方法

随着大数据时代的到来,高维数组的分析越来越困难。介绍了两种大数据线性降维的方法,通过构造计算矩阵,求解矩阵的特征值和特征向量,可以非常容易地发现数据的极小维度表示,降低后期大数据分析的复杂度。通过采用这些方法进行数据降维,可以找出数据内在的相互关系,非常有利于数据分布规律的分析。     

An erasure coding-based loss-tolerant file delivery protocol for deep spacecommunications

In deep space communications, huge delay, asymmetric bandwidth, large BER and packet loss ratio and intermittent link hinder the adoption of terrestrial transmission protocols. To decrease file delivery time, consultative committee for space data systems (CCSDS) file delivery protocol (CFDP) replaces acknowledge (ACK) by negative acknowledge (NAK) and simplifies the procedures of link establishment and link removal. However, feedback information cannot be avoided in CFDP; hence the file delivery performance cannot be further improved. Motivated by the idea of erasure coding, a one-way reliable transmission protocol named loss-tolerant file deliver protocol (LTFDP) that is suitable for deep space long-range file deliveryis proposed in this paper. For LTFDP, if a certain percent of the data segments interweaved by explorers is received, the original data can be de-interweaved successfully by Earth stations; hence reliable transmission is accomplished without NAK or ACK. Obviously, the Earth stations have enough power and memory resources for the iteration process of de-interweaving. In a shorter distance communications scenario such as from the Moon to the Earth, performance of LTFDP is greatly impacted by file size and transmission rate. In contrast, propagation delay is the main factor of file delivery time in a longer distance communication scenario, e.g. from the Mars to the Earth. This paper demonstrated that LTFDP can not only diminish file delivery time greatly and improve goodput by feedback-reduced transmission, but also improve the reliability of deep space communications.     

大型复杂构件制造过程残余应力演化与调控

归纳了残余应力的基本类型及各类残余应力的计算机仿真方法，概述了残余应力形成与演化行为及残余应力调控技术的研究现状。以机械臂基座本体淬火过程为例，展示了有限元仿真在大型复杂构件残余应力演化行为分析上的应用；以工字型材模压去应力为例，通过有限元仿真重现了变截面构件模压去应力的过程并分析了模压去应力的影响因素。讨论了残余应力仿真预测与调控技术应用于组件及其涵盖构件制造-服役全寿命周期的可行性，预测了其集成于智能制造技术体系的巨大潜力。     

空间实验室的风险识别与控制方法

以天宫一号空间实验室风险识别与控制技术需求为牵引，对风险识别与控制方法的分阶段应用提出建议。针对空间实验室的重要风险和组合体特性，提出了的相对风险识别法和降级重构风险控制法，从相对风险的角度对空间实验室重大风险进行识别，在天宫一号无法对组合体实施控制时，用载人飞船接替天宫一号对空间实验室组合体进行控制。规避了风险识别结果波动过大的问题，在不增加设备冗余和其它舱段的前提下降低了系统风险。     

基于片上网络的路由模型研究

主要探讨了片上系统网络目前的发展状况和趋势,研究了片上网络模型的拓扑结构和通信方式以及功耗.着重设计了一个片上网络的路由器模型.此路由器基于2D Mesh网络,有简洁,高效的特点.     

一种新型的体三维显示系统

利用人眼视觉暂留效应,提出了一种新型的体三维显示方式,搭建了将一系列二维切片图像融合成一幅三维立体图像的原型系统。介绍了该系统的设计思路并阐述了其主要组成元件的功能。实验证明,该系统可直接裸眼观察三维图像,而不用借助于立体眼睛等辅助工具。     

突扩燃烧室水流试验研究

对两种类型3种结构的突扩燃烧室分别进行了可视化水流模拟试验.试验结果表明,在剪切层中出现明显的旋涡结构,旋涡的产生、发展、脱落、破碎影响着燃烧室的流动状态;中心突扩燃烧室的流动状态与突扩比密切相关;在两侧突扩燃烧室中,由于两股流体的冲撞作用,导致流体周期性摆动,并在两侧卷起相对有规律的涡对,流动具有明显的低频振荡特征.