基于模糊神经网络干扰观测器的组合体航天器姿态控制

针对非合作目标存在对抗性力矩输出情况下的组合体航天器姿态控制系统,提出了一种基于模糊神经网络干扰观测器(Fuzzy Neural Network Disturbance Observer, FNNDO)的非奇异终端滑模(Nonsingular Terminal Sliding Mode, NTSM)有限时间控制策略。首先以服务航天器为基准,建立组合体航天器姿态数学模型,然后针对包含惯量不确定性、目标对抗性力矩等的等效干扰力矩,设计了一种具有自适应能力的FNNDO,可以实现对等效干扰的有效跟踪。在FNNDO的基础上,设计NTSM控制器,利用Lyapunov理论证明闭环系统的有限时间稳定性。最后,仿真实验结果表明了控制策略的有效性和观测器在观测性能上的优越性。     

Laser Hardening of Metals

The first experiments on hardening metals by laserpeening induced residual compressive stress in the sur-face of metals for improving their resistance to cracking,stress corrosion and fatigue took place more than 30years ago. However, only today, with the development ofhigh-intensity pulse repetitive rate lasers, this methodstarts to compete to traditional peening, which use influ-ence of small metal balls.Laser peening uses pulses with high intensity 109￣1010 W/cm2 [1]. The laser energy abso…     

Pc5 Oscillation Analysis by the Satellite and Ground-Based Data

Large amplitude Pc5 event was observed in the space and on ground on August 3, 2001, about three hours after contact of the strong discontinuity in the solar wind with the magnetosphere according to data from ACE and Wind satellites. The Pc5 amplitude was as high as 15 nT in the tail of magnetosphere and about 5 nT at the ground based stations. In the magnetosphere Pc5 waves were observed by Cluster and Polar satellites, which occupied positions in the morning part of the near tail at the close field lines but were parted by distance of 11.5 Re, mainly along the x-axis of the GSM coordinate system. Both compressional and transverse components of the Pc5 wave activity were observed in the space, with the transverse component having the larger amplitude. Time delay between the Cluster and Polar satellites was about 8 minutes, which could be interpreted as a wave propagation from the geomagnetic tail to the Earth with the 150 km/s group velocity. The ground-based Pc5 activity was analysed by using data from the Image magnetometer network. Doubtless demonstrations of a field line resonant structure were found in variations of amplitude and polarization with latitude. Finnish chain of search coil magnetometers observed modulated Pc1 emission simultaneously with the Pc5 wave train. A possibility of non-linear impact of Pc5 wave energy on the plasma and waves in the magnetosphere is discussed.     

The Main Results and the Perspectives in the Researches at SSRT

In this report briefly presented the contemporary state of the experimental base of Radio Astrophysical Observatory (RAO) of the Institute of Solar-Terrestrial Physics (ISTP), the methodology of radioheliographic monitoring of the solar corona, the SSRT database, the RAO Web-pages, factors limiting the effective use of SSRT. Here are formulated the original results of the basic directions of the solar activity researches and the problems solutions on SSRT: (1) active regions at various development stages, morphology, modeling,signs of energy accumulation and flares buildup, forecast of powerful flares; (2) scenario, topology and the fine temporal picture of flares development, signs of primary energy release, radio emission mechanisms, scatter effects of radio emission in turbulent corona, energetic particles fluxes; (3) filaments; (4) CME with the localization of their initiation at the solar disk background, development scenario of filament activation + CME +flare; (5) coronal holes, and (6) bright coronal points.      

A Theoretic Interpretation of Movement of the Cusp Equatorward Boundary

A preliminary model is proposed to describe quantitatively the position and movement of cusp equatorward boundary. This integrated model, consisting of an empirical model of the magnetopause and a compressed dipolar model of Open/Closed field line, connects quantitatively the solar wind conditions, subsolar magnetopause and cusp equatorward boundary. It is shown that the increasing solar wind dynamic pressure and the increasing southward Interplanetary Magnetic Field (IMF) component drive the magnetopause to move inward and the cusp equatorward. This model is adopted to interpret quantitatively the cusp movement of August 14, 2001 observed by Cluster. The results show that the subsolar magnetopause moved earthward from 10.7 He to 9.0 Re during the period of 002300-002800 UT, and correspondingly the cusp equatorward boundary shifted equatorward. The observations of Cluster C1 and C4 show the cusp equatorward boundary that Cluster Cl and C4 were crossing during same interval moved equatorward by 4.6°. The cusp equatorward boundary velocity computed in the theoretical model (10.7km/s) is in good agreement with the observed value (9.4km/s) calculated from the data of CIS of Cluster C4 and C1.     

From the Solar Wind to the Magnetospheric Substorm

This paper gives a brief outline of the progression from the first substorm model developed in Ref.[4] and[8] based on Kennel's ideas[3], to the present views about the mechanism by which solar wind kinetic energy is converted to electromagnetic energy at the Bow Shock and by which this energy is transferred to the magnetosphere in the form of current; about the transformation of the energy of this current to gas kinetic energy of convecting plasma tubes, and, finally, the back transformation of gas kinetic energy to electromagnetic energy in secondary magnetospheric MHD generators. The questions of the formation of the magnetospheric convection system, the nature of substorm break-up, and of the matching of currents in the magnetosphere-ionosphere system are discussed.      

The Nonlinear Model of the Response of Airglow to Gravity Waves

In this paper, we develope a time-dependent, nonlinear, photochemical-dynamical 2-D model which is composed of 3 models: dynamical gravity wave model, middle atmospheric photochemical model, and airglow layer photochemical model. We use the model to study the effect of the gravity wave propagation on the airglow layer. The comparison between the effects of the different wavelength gravity wave on the airglow emission distributions is made. When the vertical wavelength of the gravity wave is close to or is shorter than the thickness of the airglow layer, the gravity wave can make complex structure of the airglow layer, such as the double and multi-peak structures of the airglow layers. However, the gravity wave that has long vertical wavelength can make large scale perturbation of the airglow emission distribution.     

孔探工作在发动机维护中的重要性

孔探越来越成为节省发动机维修成本和其日常监控的有效途径。但要圆满地完成工作,内窥镜本身的技术水平和操作者的经验是不可缺少的两大要素。     

飞行数据处理的非线性鲁棒滤波技术

研究了飞机飞行试验数据处理中的非线性鲁棒滤波技术,分析给出了实际飞行条件了一种飞机运动的新模型,它是含不确定参数项的非线性模型,同时给出了该不确定参数项的解析的表达形式,然后研究了对应于此类非线不确定系统的鲁棒滤波算法,得到了该滤波问题的充分解,并对该解进行扩展线性化处理,得么了一个较易实现的扩展鲁棒滤波算法,最后利用该算法对实际的数据进行了处理,结果表明,所提出的算法是切实可行的。