Low ionization lines in high luminosity quasars: The calcium triplet

In order to investigate where and how low ionization lines are emitted in quasars we are studying a new collection of spectra of the CaII triplet at λ8498, λ8542, λ8662 observed with the Very Large Telescope (VLT) using the Infrared Spectrometer And Array Camera (ISAAC). Our sample involves luminous quasars at intermediate redshift for which CaII observations are almost nonexistent. We fit the CaII triplet and the OI λ8446 line using the Hβ profile as a model. We derive constraints on the line emitting region from the relative strength of the CaII triplet, OI λ8446 and Hβ.     

Boundary condition modelling and identification for cantilever-like structures using natural frequencies

The actual boundary conditions of cantilever-like structures might be non-ideally clamped in engineering practice, and they can also vary with time due to damage or aging. Precise modelling of boundary conditions, in which both the boundary stiffness and the boundary mass should be modelled correctly, might be one of the most significant aspects in dynamic analysis and testing for such structures. However, only the boundary stiffness was considered in the most existing methods. In this paper, a boundary condition modelling and identification method for cantilever-like structures is proposed to precisely model both the boundary stiffness and the boundary mass using sensitivity analysis of natural frequencies. The boundary conditions of a cantilever-like structure can be parameterized by constant mass, constant rotational inertia,constant translational stiffness, and constant rotational stiffness. The relationship between natural frequencies and boundary parameters is deduced according to the vibration equation for the lateral vibration of a non-uniform beam. Then, an iterative identification formulation is established using the sensitivity analysis of natural frequencies with respect to the boundary parameters. The regularization technique is also used to solve the potential ill-posed problem in the identification procedure.Numerical simulations and experiments are performed to validate the feasibility and accuracy of the proposed method. Results show that the proposed method can be utilized to precisely model the boundary parameters of a cantilever-like structure.     

具有周期性薄膜热源的多层介质非稳态传热数值仿真

为分析具有薄膜热源的多层介质非稳态传热问题,以某型飞机层合电加温风挡为例,构建了一种热流密度-温度边界条件,实现了薄膜热源热流和温度属性向多层介质内外两个方向上的实时传递,再现了薄膜热源温度对临近多层介质表面温度的影响,为具有薄膜热源的多层介质传热问题分析和加温控制规律设计提供了一种可行方法.     

第21,22周峰年太阳射电爆发中毫秒级精细结构的分析

本文对第21周的2840MHz及22周峰年的2545MHz，2645MHz和2840MHz波段上所观测到的285个快速事件进行分析，发现两个峰年的快速事件具有多种多样的快速活动（快速精细结构）．它们与耀斑的对应关系也做了统计分析．     

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.     

复合材料钻削刀具状态集成学习分类技术

刀具状态监测关系到工件加工质量,因此实时掌握刀具的磨损状态具有重要的意义。针对单一模式识别分类器的局限性,提出了基于异态集成学习模型的刀具状态监测系统。在该系统中,根据集成学习基分类器选择原则,选取了支持向量机(SVM)、隐马尔科夫模型(HMM)以及径向基神经网络(RBF)这3个单分类器作为基分类器。为了验证监测系统的有效性,进行了复合材料钻削实验,提取了加工过程中的钻削力信号、振动信号的时域特征并利用局部保持法(LPP)进行了特征选择。通过与单分类器和集成学习分类效果的对比,表明了集成学习模型相比于单一基分类器具有更高的分类精度和更好的稳定性。     

综合热管理在先进战斗机系统研制中的应用

分析了国外先进战斗机的发展情况，对比了需求的变化和发展趋势，阐述了综合热管理思想的内涵。结合中国先进战斗机的研制，论证了综合热管理的必要性和可行性。结合中国实际情况，提出了热收集、热传输、热排散等综合优化设计方法，采用了多路径高效热收集传输手段、基于隐身的热排散等工程实现途径。综合应用基于温度控制的流量调节、内外循环热综合控制、多模式重构技术等手段，实现了热沉与制冷量的管理，满足了不同状态的热管理需求。针对未来的发展方向以及战斗机热管理面临的难题，提出了一定的见解。     

基于数据挖掘的航空发动机状态参数离群点分析

利用机载数据采集系统和传感器获得的发动机状态参数往往存在粗大误差，影响故障诊断的准确性。采用数据挖掘算法中基于统计学的离群点分析，并与厂家系统的分析结果相比较，结果表明，该方法能够有效地剔除粗大误差且不会误删有用数据。     

On bandwidth of solar subsecond bursts in cm-range

The goal is to study parameters of drifting type III bursts, and find out the emission mechanism of these bursts and understand what factors affect instantaneous spectral bandwidth of these bursts.