A SMGCS滑行道冲突预测与避免控制

针对先进机场场面引导与控制系统(Advanced surface movement guidance and control system,A-SMGCS)滑行道冲突预测与避免控制,提出基于事件反馈的闭环控制框架,并重点解决对头冲突预测与避免控制问题。建立滑行道受控着色Petri网模型。提出航空器可控滑行路段概念,并给出其对应子模型的生成规则。利用子模型中环路和环路链,给出无对头冲突的充分必要条件。提出对头冲突避免控制策略,以及适合实时控制的对头冲突预测与避免控制算法。算例表明本文能根据场面状态及时识别对头冲突并实现冲突避免。     

动载下热防护系统典型组件防热有效性研究

在给定热环境及动态随机载荷条件下,对某航天飞行器大面积热防护系统进行了力热耦合及随机振动分析,得出在该条件下的块间开缝位移.随后建立缝隙内的热传导模型,并依据开缝位移值,分析了它对大面积背温的影响.同时,还研究了在不同参数对防热有效性的影响规律.     

FJ44发动机关键性能参数趋势分析

以FJ44型发动机为研究对象,选择采集该型发动机的几个关键性能参数,对数据平滑处理后进行趋势分析,监控发动机状态,并为其故障诊断提供参考。     

地磁导航的迭代评价匹配算法

针对现有地磁匹配基本算法在数据批处理上实时性能的不足和需要预先指定匹配数据序列长度的困难,提出了一种用于地磁导航的迭代评价匹配算法(Iterative evaluation matching algorithm,IEMA)。基于迭代求解思想,将算法时间分散在各个采样时刻,同时采用实时评价方式,在每一步迭代求解后根据实际情况来判断是否可以输出匹配定位结果。试验结果表明,迭代评价匹配算法应用于地磁导航是有效可靠的,并且它能够自适应调整匹配数据序列的长度。     

特征加权的阴影C均值聚类新算法(英文)

将特征加权的划分聚类方法应用在阴影集的框架中阴影聚类产生的核心区和边界区的样本对每一个类的质心有不同的影响。通过集成特征权重,加权计算的公式引入到聚类算法中。权重指数的选择对于好的聚类结果非常关键,而且权重随着每次迭代划分而更新。文中给出了算法的收敛性,并且使用了可行的聚类有效性指标。在合成数据集和真实数值数据集上的不同特征权重的实验结果表明,该加权算法优于其他不加权算法。     

协同决策机制下的时隙二次指派

随着中国民航的快速发展,航班不正常变得越来越严重。由空管、航空公司与机场三方构建的协同决策机制成为应对该局面的重要手段。本文研究航空公司在协同决策机制下,当时隙资源发生严重不足时,对时隙进行二次指派的方法。文中建立了一种基于航班波运行方式的航班时隙指派模型,针对模型的特点与实时决策要求采用模拟退火算法求解。最后通过实例证明了采用本文的方法可以大幅度减少旅客总延误时间。     

V-BLAST BASED LDPC-CODED RELAY COOPERATION

An efficient LDPC-coded multi-relay cooperation architecture is proposed based on virtual vertical Bell Labs layered space-time （V-BLAST） processing for uplink communication, where minimum-mean-square-error （MMSE） and BP-based joint iterative decoding based on the introduced muhi-layer Tanner graph are effectively de- signed to detect and decode the corrupted received sequence at the destination. By introducing V-BLAST transmis- sion to the coded multi-relay cooperation, relays send their streams of symbols simultaneously, which increases the data rate and significantly reduces the transmission delay. The theoretical analysis and numerical results show that the new LDPC coded cooperation scheme outperforms the coded non-cooperation under the same code rate, and it also achieves a good trade-off among the performance, signal delay, and the encoding complexity associated with the number of relays. The performance gain can be credited to the proposed V-BLAST processing architecture and BP-based joint iterative decoding by the introduced multi-layer Tanner graph at a receiver-side.     

Libration point orbit rendezvous using PWPF modulated terminal sliding mode control

The near-range rendezvous problem of two libration point orbit spacecraft in the Earth–Moon system is studied using the terminal sliding mode control which enables a time-fixed process with the flight time prescribed a priori. The underlying dynamics are the full nonlinear equations of motion for a complete Solar System model. For practical purposes, two means of pulse-width pulse-frequency (PWPF) modulation are employed to realize the theoretical continuous control with a series of thrust pulses. Extensive simulations with major errors taken into account show that the sliding mode controller can successfully guide the chaser to a given staging node with the final position and velocity errors, on average, lower than 20 m and 1 mm/s, respectively. Compared with the glideslope guidance previously studied, the proposed approach outperforms the former by saving approximately 50–60% of total delta-v.     

Epistemic uncertainty quantification in flutter analysis using evidence theory

Aimed at evaluating the structural stability and flutter risk of the system, this paper manages to quantify epistemic uncertainty in flutter analysis using evidence theory, including both parametric uncertainty and method selection uncertainty, on the basis of information from limited experimental data of uncertain parameters. Two uncertain variables of the actuator coupling system with unknown probability distributions, that is bending and torsional stiffness, which are both described with multiple intervals and the basic belief assignment(BBA) extricated from the modal test of actuator coupling systems, are taken into account. Considering the difference in dealing with experimental data by different persons and the reliability of various information sources, a new combination rule of evidence––the generalized lower triangular matrices method is formed to acquire the combined BBA. Finally the parametric uncertainty and the epistemic uncertainty of flutter analysis method selection are considered in the same system to realize quantification. A typical rudder of missile is selected to examine the present method, and the dangerous range of velocity as well as relevant belief and plausibility functions is obtained. The results suggest that the present method is effective in obtaining the lower and upper bounds of flutter probability and assessing flutter risk of structures with limited experimental data of uncertain parameters and the belief of different methods.     

贝叶斯网络在飞控系统可靠性评估中的应用

把一种基于贝叶斯网络的故障树分析法应用于飞控系统俯仰控制功能的可靠性评估中,突破传统故障树分析法的局限性——各部件独立、状态为二值,不但可以计算系统的可靠性指标,而且可以定量给出某个事件或某几个事件在系统可靠性中所占的地位,找出系统的薄弱环节。