基于马氏距离的航空发动机健康监控方法

航空发动机健康监控是实现航空发动机健康管理的关键技术之一。针对航空发动机健康监控高维计算复杂度高的问题,提出了一种基于主成分分析与马氏距离结合的计算方法。首先通过主成分分析对性能监测参数进行降维,并采用马氏距离计算发动机的健康参数,最终根据威布尔分布确定健康参数的警戒值。实例计算结果表明,方法能够较好反映航空发动机健康状态,并能检测运行过程中出现的异常点。     

Study of the ionosphere during a magnetospheric storm using data on the ground and in space

For the magnetospheric storm of May 14–16, 1997 geophysical data of satellites DMSP and IMP-8 are compared with data of radio propagation on the high-latitude HF radio path of Heiss Island – St. Petersburg and data from European ionosondes. Peculiarities of variations of the operational frequencies range MOF–LOF (maximum and lowest observed frequencies) on the path were considered. The range has been determined by the method of oblique ionospheric sounding (OIS). The latter is more informative for observations during a magnetic storm compared to the vertical sounding method. Nevertheless, an analysis of variations of the critical frequency of the ionospheric F2 layer from the chain of European ionosondes was carried out. For interpretation of results, data of magnetospheric parameters, AE-indexes and riometer data were used. The variations of both frequency range on the path and critical frequencies of the F2 layer through the ionosondes chain during the disturbed period had certain regularities of behaviour. These regularities are being explained from the physical point of view. The analysis of the satellite DMSP data has showed that a magnetospheric disturbance causes displacement equatorward of precipitation and some growth of its width and energy.     

Some peculiarities of longitudinal distribution of proton fluxes at high latitudes

Dynamical features of proton fluxes at high and middle latitudes were studied based on data measured by Sun-synchronous low-altitude (800 km height) polar-orbiting three NOAA series satellites: POES 15, 16, and 17 during the geomagnetic storm on January, 21–22, 2005. Data from three satellites that passed the Northern hemisphere along different MLTs allow reconstructing the longitudinal distribution of the proton fluxes. Measurements of protons with energies of 30–80 keV and 80–240 keV (the ring current energy range) by 0- and 90-detectors were used to evaluate and compare the longitudinal asymmetry of proton flux distribution measured in the regions equatorward and poleward of the isotropic boundary. It was found that during all the phases of the geomagnetic storm distribution of the maximum flux of precipitating protons (0-detector data) is sufficiently asymmetric. The maximal flux position along MLT is moving from pre-midnight sector in quiet time to post-midnight one before and during SSC and moving back during recovery phase. The longitudinal distribution of precipitation maxima demonstrates the local increase in afternoon sector (approximately at 13:30 MLT) and decrease in the dusk one during SSC. These features are evident consequence of the magnetosphere compression. To identify the origin of the particles, the locations of maximum fluxes have been projected to the magnetosphere. It was determined that during geomagnetic storm main and recovery phases maximum fluxes were measured at latitudes poleward of the isotropic boundary. To evaluate the trapped particle flux asymmetry, the particle fluences (90-detector data) were calculated along the satellite orbit from L = 2 to the isotropic boundary. The total fluences of trapped particles calculated along the satellite orbit show regular asymmetry between dusk and dawn during main and recovery phases. The maximal intensity of proton fluxes of both investigated populations located poleward and equatorward of the isotropic boundary is achieved during SSC. The total flux measured during crossing the anisotropic region can be considered as a proxy for ring current injection rate.     

高精度测量燃气轮机叶片前缘的三维轮廓

为了解决高精度测量燃气轮机叶片前缘三维轮廓的难题,提出了一种基于球阵列标定检验方法,直接对金属表面的叶片前缘三维轮廓进行高精度测量的相位轮廓测量系统.通过多角度数据融合算法和非线性最小二乘的递归算法,最后高精度测量出叶片前缘三维轮廓,对叶片前缘16个剖面进行拟合,得出了叶片前缘半径和前缘圆心.结果显示:叶片前缘测量系统、方法和算法的综合误差为±0.03mm.此实验装置和方法测量效率高、精度高,将叶片测量和模型化技术推进了一步.      

航空发动机健康管理云服务系统设计与实现

为提高航空公司的资源利用率和经营管理水平,设计了一个基于云计算的航空发动机健康管理系统。分析了航空公司对云服务系统的需求,介绍了系统的结构体系和系统开发和运行的环境。叙述了系统的功能模型和信息模型,并通过发动机健康管理一个模块——“水洗”的使用来说明系统的使用过程。     

飞机健康状况量化分析方法浅析

提出与飞机健康状况相关的事件参数、风险参数的概念,具体阐述了建立量化模型的思路和方法。该方法简单可靠,具有较强的可扩展性,可为飞机的技术派遣提供决策支持。     

某型飞机作动器健康现状的评判

通过结合层次分析法和专家经验综合考虑其各影响因素的权重,并通过建立模糊综合评判矩阵对某型飞机作动器作出综合性、定量的评价,由定性评价转化为客观公正的定量评价.根据评判结果对飞机作动器的健康现状作出正确的判断,并对进一步的检修提供建议.     

复合材料飞机结构健康监测系统的若干问题探讨

针对飞机复合材料结构状态监测技术,从结构健康监测系统、结构健康监测研究对象和损伤识别方法,以及复合材料飞机的结构设计和结构健康监测系统三方面之间的关系进行阐述。分析了复合材料飞机结构健康监测系统的发展趋势,并讨论了制约该技术发展的因素。     

飞机预测与健康管理体系结构浅析

飞机预测与健康管理(Prognostics and Health Management,PHM)是以美国JSF飞机为代表的新一代飞机自主后勤概念的核心.PHM技术的应用,有效地降低了飞机全寿命周期的使用维护费用,提高了飞机战备完好率和任务成功率,保证了飞机及其各系统能够安全、可靠、高效地运行.本文在分析了美国JSF飞机...     

A data-driven health indicator extraction method for aircraft air conditioning system health monitoring

Prognostics and Health Management (PHM) has become a very important tool in modern commercial aircraft. Considering limited built-in sensing devices on the legacy aircraft model, one of the challenges for airborne system health monitoring is to find an appropriate health indicator that is highly related to the actual degradation state of the system. This paper proposed a novel health indicator extraction method based on the available sensor parameters for the health monitoring of Air Conditioning System (ACS) of a legacy commercial aircraft model. Firstly, a specific Airplane Condition Monitoring System (ACMS) report for ACS health monitoring is defined. Then a non-parametric modeling technique is adopted to calculate the health indicator based on the raw ACMS report data. The proposed method is validated on a single-aisle commercial aircraft widely used for short and medium-haul routes, using more than 6000 ACMS reports collected from a fleet of aircraft during one year. The case study result shows that the proposed health indicator can effectively characterize the degradation state of the ACS, which can provide valuable information for proactive maintenance plan in advance.