飞机结构数字孪生关键建模仿真技术

飞机结构安全性设计思想经历了从静强度设计、安全寿命设计、损伤容限与耐久性设计到单机追踪的演变,未来有进一步向结构数字孪生的方向发展的趋势。飞机结构数字孪生是数字线程驱动的,多学科、多物理、多尺度、多保真度、多概率的模拟仿真系统,采用在线传感器监测、离线地面检查、飞机运行历史等多源数据,反映并预测对应飞机结构实体在全寿命周期内的行为和性能,有望革新现有的飞机结构使用和维护模式。面向疲劳寿命管理,提出飞机结构数字孪生的5项关键建模仿真技术,分别是载荷和损伤的数据获取技术、多尺度建模和力学分析技术、含裂纹复杂结构的精确高效仿真技术、基于降阶的数字孪生高效建模技术和考虑不确定性与多源异构数据的剩余寿命评估技术,并详细探讨这五项关键技术的研究现状与发展方向,为飞机结构数字孪生的系统研究与工程应用提供参考。     

多目标模糊决策模型及其在载人航天中应用的探讨

为了探讨在与载人航天相关问题中进行优化决策的方法,根据模糊数学理论,首先提出模糊接近度的概念;然后计算模糊关系矩阵和相对广义加权接近距离,据此建立了多目标模糊决策模型。最后,以确定中长期载人航天器座舱内航天员的人数为实例,进行了具体的模糊决策,所得结果具有参考价值。     

涡轮集气腔出流流量分配和温度特性研究

采用模型实验和数值方法,针对特定的涡轮集气腔结构进行了出流特性研究。首先,在实验室条件下,进行全尺寸基准涡轮集气腔的模型实验研究并验证数值模拟方法;其次,在接近发动机真实气-热参数条件下进行系列的数值模拟,分析进出口压比、腔室高度、出流孔孔径和出流孔轴向位置等对出流孔流量分配和温度分布的影响。研究表明,除了集气腔出流流量分配的不均匀性之外,气流与热壁面之间的对流换热也导致明显的出流温度不均匀性;改变出流孔轴向位置距离、增加集气腔腔室高度是在不影响集气腔通流能力下改善出流均匀性的有效技术措施,当出流孔轴向偏置距离或集气腔腔室高度达到一定值后,其对改善出流流量分配均匀性的作用趋于微弱,但对于改善出流温度分布均匀性依然有较好的作用。     

通信卫星平台热分析建模方法研究及温度预示

对通信卫星平台进行热分析 ,用热平衡试验结果对计算结果进行比对和修正 ,达到计算误差与试验误差基本在± 5℃范围内的效果 ,确立该平台热分析建模方法 ,该方法也可为其它卫星平台所借鉴     

神舟飞船项目管理成熟度模型研究

在综合分析国际上典型的项目管理成熟度模型的基础上,结合神舟飞船项目及其组织环境的特点,建立了神舟飞船项目管理成熟度模型(SZ-PMMM)。该模型由面向企业级组织和面向项目级组织的两个项目管理成熟度模型组成。在SZ-PMMM中引入“文化”等关键领域,关注企业级组织中多项目间管理能力的差异性,拓展了项目管理成熟度的内涵,对各级组织项目管理能力的评价与改进有重要意义。     

基于dSPACE的频率特性测试与模型辨识研究

为了满足伺服控制系统设计需要,提出了一种利用dSPACE系统对被测对象进行频率特性测试与模型辨识的方法,对该方法所使用的激励信号与响应数据处理进行了研究。利用dSPACE硬件平台产生离散正弦扫频信号,利用软件合成的方法实现相关分析运算,使用Matlab进行数据处理,完成被测对象频率特性曲线绘制,采用Levy方法进行了模型辨识。应用结果表明,该方法使用方便,对传递函数具有较高的辨识精度,可以为控制算法设计提供理论依据。     

基于频响函数模型修正影响因素的仿真

首先推导了基于频响函数模型修正的理论公式,在此基础上通过平面桁架模型修正的仿真算例,比较研究了基于频响函数模型修正方法具体实现过程中数据测量噪声、频率点选择以及频段选择等因素对修正结果的影响。研究表明,频率点的选择是基于频响函数模型修正的关键因素,合理的频率点选择既能够减小计算量,降低修正方程的条件数,同时还能够抑制测量噪声的影响;此外,提高实测数据的精度,增加修正频段的宽度也是改善模型修正效果的有效手段。     

Impact of loading effects on determination of the International Terrestrial Reference Frame

The International Terrestrial Reference Frame (ITRF), as a realization of the International Terrestrial Reference System (ITRS), is represented by a set of station positions and linear velocities. They are intended to be used as regularized coordinates to which some corrections should be added to access instantaneous coordinates. The latest ITRS realization is the ITRF2005, which has integrated time series of station positions to form long-term solutions for the four space geodetic techniques. Currently, a purely linear model is used to parameterize station displacements in the estimation process, plus occasional discontinuities in case of earthquakes or equipment changes. However the input data have been derived without applying surface loading models and so surface loading effects are supposed to be embedded in the coordinates as measured quantities. We evaluate the effect of applying a posteriori loading corrections, which include the effect of atmospheric, non-tidal ocean, and continental water loading, to time series of positions estimated from Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), and Global Positioning System (GPS) data. We notice that they reduce about 50% or more of the annual signals in the translation and scale parameter time series of the SLR and VLBI techniques, except in SLR Z translation. In general, the estimated secular frame definition is negligibly affected and estimated positions and velocities are not significantly modified for stations that have accumulated a large number of observations. A multi-technique combination of such derived frames allows concluding that, for some cases, loading model corrections might degrade co-located station coordinates almost as much as they benefit them. However, most significant improvement of the estimated secular coordinates is observed for stations with less than 100 estimated positions as demonstrated with a multi-technique combination.     

基于多模型滚动时域估计的卫星故障诊断

研究了卫星姿态控制系统故障诊断问题, 将滚动时域估计与交互式多模型(IMM)方法相结合, 利用滚动时域估计方法对系统状态进行估计, 系统转换概率也相应地利用了一个时间段的估计误差作为依据, 而不是只考虑一个时刻的估计误差, 因此有效减少了大噪声以及个别错误测量对诊断结果的影响. 最后的仿真结果证明了该算法的有效性.      

Integrating Non-Tidal Sea Level data from altimetry and tide gauges for coastal sea level prediction

The main objective of this paper is to integrate Non-Tidal Sea Level (NSL) from the joint TOPEX, Jason-1 and Jason-2 satellite altimetry with tide gauge data at the west and north coast of the United Kingdom for coastal sea level prediction. The temporal correlation coefficient between altimetric NSLs and tide gauge data reaches a maximum higher than 90% for each gauge. The results show that the multivariate regression approach can efficiently integrate the two types of data in the coastal waters of the area. The Multivariate Regression Model is established by integrating the along-track NSL from the joint TOPEX/Jason-1/Jason-2 altimeters with that from eleven tide gauges. The model results give a maximum hindcast skill of 0.95, which means maximum 95% of NSL variance can be explained by the model. The minimum Root Mean Square Error (RMSe) between altimetric observations and model predictions is 4.99 cm in the area. The validation of the model using Envisat satellite altimetric data gives a maximum temporal correlation coefficient of 0.96 and a minimum RMSe of 4.39 cm between altimetric observations and model predictions, respectively. The model is furthermore used to predict high frequency NSL variation (i.e., every 15 min) during a storm surge event at an independent tide gauge station at the Northeast of the UK (Aberdeen).