基于动态故障树分析的民用飞机辅助动力装置系统安全性评估

在民用航空工业领域,传统的故障树分析方法广泛运用于系统安全性评估。然而,包含系统/子系统运行的时序阐述以及备份、冗余表达在内的动态特性不能通过传统故障树呈现。另一方面,民用飞机辅助动力装置(APU)经常作为一个冗余系统运作,因而其行为可以通过运用动态故障树进行适当的描述。所以APU的这种特性激发了动态故障树分析在APU系统安全性评估上应用的关注。首先介绍了两种动态门(优先与门和冷备件门),其定量计算通过施用马尔可夫模型来呈现;然后分别通过传统故障树以及动态故障树分析了APU系统安全性评估的两个典型案例;最后进行了两种故障树分析(FTA)的比较,其结果显示出通过合理的应用,动态故障树(DFTA)方法达到了对于真实情况来说相当高的精度,并且对指数分布函数施用二阶近似后,其运算成本也是可以接受的。     

基于BLUE的多窗口谱估计

文章提出了一种基于BLUE的多窗口功率谱估计算法。该算法是在无偏估计的约束条件下，使其方差最小化而得到的特征谱的最佳线性组合。通过仿真实例分析得到，与自适应的MTM相比，该算法的计算量大大减小了。由于正弦窗具有解析的表达式，不需要进行特征值分解，并且有良好的统计性能，因此，使用正弦窗的MTM可以进一步降低计算量并改善估计性能。     

模糊层次分析法在机场备用电源选择中的应用

传统观念认为只有柴油发电机组才适合作机场备用电源，其实国际民航组织并没有对备用电源采用何种设备做出具体限制，备用电源的选择面很广。结合当前新兴的微型燃气轮机发电技术和燃料电池发电技术，采用模糊层次分析法(Fuzzy AHP)，对这三种电源进行综合性能评价，把难以量化的因素数字化，做出了具体的方案排序向量，为设计人员在实际工程中选用备用电源提供了参考。     

A tentative statistical analysis of flare events observed by NoRH and NoRP

In this paper, we report the statistical analysis of flare events observed by NoRH during 1992–2005 and NoRP during 1994–2005. We give the power law indices for the frequency distribution of peak brightness temperature which is 1.87 ± 0.05 for 17 GHz observation and is 1.64 ± 0.04 for 34 GHz observation. We also present the frequency variation of power law indices for peak flux and total energy of flare for NoRP observation, which is mono-increasing from 1 to 17 GHz.     

Two freedom linear parameter varying μ synthesis control for flight environment testbed

To solve the problem of robust servo performance of Flight Environment Testbed(FET)of Altitude Ground Test Facilities(AGTF) over the whole operational envelope, a two-degree-offreedom μ synthesis method based on Linear Parameter Varying(LPV) schematic is proposed, and meanwhile a new structure frame of μ synthesis control on two degrees of freedom with double integral and weighting functions is presented, which constitutes a core support part of the paper. Aimed at the problem of reference command's rapid change, one freedom feed forward is adopted, while another freedom output feedback is used to meet good servo tracking as well as disturbance and noise rejection; furthermore, to overcome the overshoot problem and acquire dynamic tuning,the integral is introduced in inner loop, and another integral controller is used in outer loop in order to guarantee steady errors; additionally, two performance weighting functions are designed to achieve robust specialty and control energy limit considering the uncertainties in system. As the schedule parameters change over large flight envelope, the stability of closed-loop LPV system is proved using Lyapunov inequalities. The simulation results show that the relative tracking errors of temperature and pressure are less than 0.5% with LPV μ synthesis controller. Meanwhile, compared with non-LPV μ synthesis controller in large uncertainty range, the proposed approach in this research can ensure robust servo performance of FET over the whole operational envelope.     

Empirical analysis of airport network and critical airports

Air transport network, or airport network, is a complex network involving numerous airports. Effective management of the air transport system requires an in-depth understanding of the roles of airports in the network. Whereas knowledge on air transport network properties has been improved greatly, methods to find critical airports in the network are still lacking. In this paper, we present methods to investigate network properties and to identify critical airports in the network. A novel network model is proposed with airports as nodes and the correlations between traffic flow of airports as edges. Spectral clustering algorithm is developed to classify airports. Spatial distribution characteristics and intraclass correlation of different categories of airports are carefully analyzed. The analyses based on the fluctuation trend of distance-correlation and power spectrum of time series are performed to examine the self-organized criticality of the network. The results indicate that there is one category of airports which dominates the self-organized critical state of the network. Six airports in this category are found to be the most important ones in the Chinese air transport network. The flights delay occurred in these six airports can propagate to the other airports, having huge impact on the operation characteristics of the entire network. The methods proposed here taking traffic dynamics into account are capable of identifying critical airports in the whole air transport network.     

平均电流型功率因子校正电路的研究

研究一种新的功率因子校正器件ＵＣ３８５４的基本原理，技术特点，着重讨论功率因子校正电路物工作原理及设计要点，并给出一个２ｋＷ样机的验证结果。     

STS2111A模块式DC＼DC转换器测试仪的研制

介绍了主要适用于各种直流电源变换器的STSZllIA测试仪的硬件、软件组成以及系统测试的主要性能技术指标，并着重讨论了参数测试时的两个关键问题的解决。该测试仪性能优良、操作简单、使用方便、适用范围广，具有较好的准确度和稳定性，是保证DC／DC电路产品质量的重要检测手段。     

小卫星技术的若干进展

本文评述了国际上应用小卫星在结构、电源和操作系统等领域新近的若干进展.在结构方面侧重于新材料、新器件和新工艺的介绍;在新型电源方面包括了有关太阳电池和蓄电池的内容;在操作系统方面强调了自主控制领域中的新观念和新方案.      

直流电源输出阻抗测量技术

直流电源输出阻抗是新的特性参数,一些电源产品开始把它列入技术指标手册中。本文分析了电源阻抗的定义,总结了电源阻抗的特点,综述了当前电源阻抗测量技术的现状,提出了基于数字电桥的一种测量方法,提出了直流电源阻抗测量中的技术难点和尚待解决的技术问题。