非线性系统的右独立阶及其应用

定义非线性右可逆系统的一组结构常量, 即右独立阶. 证明右独立阶在正则静态反馈下保持不变,同时举例指出右独立阶在正则动态反馈下可以改变. 研究了右独立阶在解耦问题中的应用, 指出利用右独立阶可完全刻划正则静态反馈解耦问题,并初步讨论了右独立阶在非线性Morgan问题上的应用.     

飞机突防飞行非线性解耦控制系统的混合仿真研究

飞机低空突防作地形跟踪／回避飞行时，会出现纵向和横向运动的非线性交叉耦合，利用非疆性逆系统理论和现代最优控制理论可以设计一个飞行控制规律来解开这些耦合，主要讨论了这种线性解耦控制系统的混合仿真，给了用于仿真的数学模型以及仿真方法，对系统有无大气紊流扰动的解耦控制、系统对指令输入的跟踪、飞行品质等方面进行了探讨。结果表明，该控制规律在有无大气紊流影响时都能实现解耦，准确地跟踪期望的三维突防航迹，并具     

基于自由尾迹的共轴直升机航向/总距解耦分析

共轴式直升机的航向操纵主要依靠上下旋翼的总距差动实现,在总距和航向操纵上有较强的耦合.利用自由尾迹算法对在研小型共轴式直升机悬停时的航向和总距间的解耦进行了计算,得到了悬停时航向与总距操纵时上下旋翼的总距配合曲线,总结了解耦控制的特点并根据数值计算结果拟合出了近似的解耦函数,计算结果对飞控系统的设计具有重要的指导意义.      

奇异摄动法在考虑执行机构系统设计中的应用

针对被控对象的执行机构对控制系统的影响，采用三重时间尺度的奇异摄动方法来展示闭环跟踪系统的渐近结构特性，从而极大地方便了解耦控制律的设计和控制矩阵的确定。并以考虑执行机构及旋翼动态的某型直升机为例，进行了多重模型／解耦控制律设计和仿真。     

基于ESO的高超声速飞行器解耦控制

针对高超声速飞行器三通道具有强耦合的问题,提出一种基于扩张状态观测器的全通道解耦控制方法。该方法不需要根据耦合项特点设计耦合补偿模型,而是通过设计扩张状态观测器,将高超声速飞行器耦合项视为扰动,利用扩张状态观测器具有实时跟踪估计扰动的能力,将耦合项扰动估计出来。通过补偿控制来消除耦合的影响,从而完成解耦控制。进一步,通过LQR控制方法完成姿态控制系统的闭环反馈控制律设计,最终实现一种工程上实用的高超声速飞行器解耦控制方法,并通过数学仿真验证了该控制方法的正确性和有效性。     

惯性解耦的多体系统动力学方程

对一类含自由－自由弹性梁的多体系统动力学方程进行了研究，利用多体系统的结构特性和运动特性对其动力学方程进行了简化，使惯性质量矩阵为对角形，得到了惯性解耦的多体系统动力学方程，在方程的数值求解时，可提高计算速度和精度，为多体系统动力学的实时仿真提供方便。     

基于一维传感器的四维力测试平台设计与分析

利用一维力/力矩传感器设计可以测量升力、滚转力矩、俯仰力矩、偏航力矩的四维测试平台.通过将3个相同的拉压力传感器并联,并利用万向节作连接件,解决了多维传感器的维间耦合误差问题,可以将3个传感器输出的力通过解耦矩阵准确无误地计算出2个力矩和1个力,从原理上完全解耦,提高了多维传感器的精度.同时此种安装方式结构简单,方便拆卸.分析了测试台的各种误差来源,并求解出误差传递函数,计算出由机械平台水平度和传感器安装误差给测试平台带来的系统误差不超过0.5%,同时分析了传感器测量精度对测试系统随机误差的影响,并计算了使用某型号传感器时的随机误差对系统整体误差的影响,验证了该方案的高精度性.     

关于一类非线性仿射系统的开环解耦问题

考虑非线性开环控制解耦问题。对予Isidori引入的一类非线性仿射系统,给出了最大能控性分布的一种开环解释。由此,对于这类系统,解决了开环控制解耦问题。     

飞轮控制的欠驱动刚体航天器姿态控制器设计

针对"三正交加斜装"反作用轮系统中某两个本体轴上的飞轮失效的欠驱动情况,研究了航天器的姿态控制问题.在系统初始角动量为零的条件下,设计分段解耦控制律,实现了姿态稳定.采用欧拉角描述法建立了欠驱动航天器的姿态动力学方程和运动学方程.在系统初始角动量为零的条件下,通过分析方程的解耦特性,设计了分段解耦控制律.该方法经过6次机动控制,可实现姿态稳定.数值仿真验证了方法的有效性.     

一种求非线性规划全局最小解的算法

在评述了近２０年来发展的全局最优化方法之后，提出了一种求解全局最优化问题的算法，即从一个求得的局部最小解点出发，去解一个最大化问题，这个最大化问题是构造一个辅助函数去寻求一个更好的局部最优解，这样就产生一个局部最小解序列，得后得到全局最小解，另外还有了全局收敛性定理，也给出了数值例子。     

New line profiles of Li–H2 for brown dwarfs

In order to calculate the opacity of a gas it is necessary to consider how its constituent atoms are perturbed by the surrounding medium. This is required both in order to calculate the equation of state, and in order to determine the profiles of the spectrum lines. In this work we report new theoretical Li line profiles perturbed by H₂ and their dependence with temperature.     

MPLS流量工程体系结构优化研究

对支持流量工程的各种显式路由算法进行了比较,提出了在线分布实施MPLS(Multi-Protocol Label Switch)流量工程的优化体系结构.通过引入扩展LSA(Link State Advertisement)发布机制,采用分布和集中相结合的方式,使最小干涉路由算法的性能得到优化,同时提高了系统的可扩展性.      

Comprehensive data reduction package for the Immersion GRating INfrared Spectrograph: IGRINS

We present a Python-based data reduction pipeline package (PLP) for the Immersion GRating INfrared Spectrograph (IGRINS), an instrument that covers the complete H- and K-bands in one exposure with a spectral resolving power of 40,000. The reduction steps carried out by the PLP include flat-fielding, background removal, order extraction, distortion correction, wavelength calibration, and telluric correction using spectra of A type standard stars. As the spectrograph has no moving parts, the PLP automatically reduces the data using predefined functions for the processes of order extraction, distortion correction, and wavelength calibration. Before the telluric correction of the target spectra, the intrinsic hydrogen absorption features of the standard A star are removed with a Gaussian fitting algorithm. The final result is the flux of the target as a function of wavelength. Users can customize the predefined functions for the extraction of the spectrum from the echellogram and adjust the parameters for the fitting functions for the spectra of celestial objects, using “fine-tuning” options, as necessary. Presently, the PLP produces the best results for point-source targets.     

四元数微分方程最小参数解法研究

对一种求解正交矩阵微分方程的三阶最小参数方法进行改造 ,将其用于四元数微分方程求解 ,并对其在捷联惯性导航系统姿态矩阵实时求解中的应用进行了仿真。结果表明 ,其计算精度比经典的三阶Peano Baker数值解法提高 35倍 ,而浮点运算次数则仅为后者的一半 ,对于提高捷联惯性导航系统姿态计算的精度具有重要意义。     

Improved orbital parameters of accreting millisecond pulsar SAX J1808.4-3658

We analyze the three outbursts of the X-ray millisecond pulsar SAX J1808.4-3658 that occurred in 1998, 2000, and 2002 observed with RXTE. With a technique based on epoch folding search we find an unique orbital solution valid over the five years of high temporal resolution data available. We revise the estimate of the orbital period, P_orb = 7249.1569(1) s and of its error, which we decrease by one order of magnitude. We also give the first constraint on the orbital period derivative, . We find that in 2002 the pulse profile shape is clearly asymmetric, showing a secondary peak at about 145° from the main pulse, which is different from the sinusoidal shape reported at the beginning of the 1998 outburst.     

Efficiency tests for estimating the gas and stellar population parameters in Type 2 objects

We investigated the efficiency of estimating characteristics of stellar populations (SP) and Active Galactic Nuclei (AGN) emission using ULySS code. To analyze simultaneously AGN and SP components in the integrated spectrum of Type 2 active galaxies, we modeled the featureless continuum (FC) and emission lines, and we used PEGASE.HR stellar population models provided by ULySS. In order to validate the method, we simulated over 7000 integrated spectra of Seyfert 2 galaxies. Spectra were generated using different characteristics of the featureless AGN continuum, signal-to-noise ratio (SNR), spectral ranges, properties of emission lines and single stellar population (SSP) model whose initial mass function (IMF) and abundance pattern is similar to the solar neighborhood. Simulated spectra were fitted with ULySS to evaluate the ability of the method to extract SP and AGN properties. We found that the analysis with ULySS can efficiently restore the characteristics of SP in spectra of Seyfert 2 AGNs, where signal-to-noise ratio is higher than 20, and where SP contributes with more than 10% to the total flux. Degeneracies between AGN and SP parameters increase with increasing the AGN continuum fraction, which points out the importance of simultaneous fitting of the FC and SP contributions.     

基于可诊断性约束的测点优化配置研究

为提高卫星的安全性和可靠性,适应在设计阶段对故障诊断进行考虑的需求,以动量轮为例,将故障可诊断性作为优化目标,提出基于DM分解技术的测点优化配置方法,并给出故障可诊断性评价的相关定义.分析动量轮模型和故障,建立动量轮的结构模型;采用DM技术对动量轮的结构模型进行分解,并分析动量轮模型的解析冗余关系;在对各故障的可检测性和可分离性进行分析的基础上,根据结构模型的偏序关系,获得使故障具有可检测性和可分离性的最小传感器集合;给出故障可诊断性评价的定义,并针对两种传感器配置情况,进行可诊断性分析.本文所提方法为设计阶段开展故障诊断的研究提供了借鉴和参考.     

Are Boltzmann plots of hydrogen Balmer lines a tool for identifying a subclass of S1 AGN?

It is becoming clear that we can define two different types of nearby AGN belonging to the Seyfert 1 class (S1), on the basis of the match of the intensities of their Broad Balmer Lines (BBL) with the Boltzmann Plots (BP). These two types of S1 galaxies, that we call BP-S1 and NoBP-S1, are characterized, in first approximation, by Broad Line Regions (BLR) with different structural and physical properties. In this communication, we show that these features can be well pointed out by a multi-wavelength analysis of the continuum and of the broad recombination Hydrogen lines, that we carry out on a sample of objects detected at optical and X-ray frequencies. The investigation is addressed to verify whether BP-S1 are the ideal candidates for the study of the kinematical and structural properties of the BLR, in order to derive reliable estimates of the mass of their central engine and to constrain the properties of their nuclear continuum spectrum.     

Statistical study of electrostatic solitary waves associated with reconnection: Geotail observations

The role of waves in the dynamics of the magnetotail has long been a topic of interest in magnetospheric physics. The characteristics of Electrostatic Solitary Waves (ESWs) associated with reconnection have been studied statistically in the magnetotail by surveying the large amounts data obtained from Waveform Capture (WFC) which is an important component of Plasma Wave Instrument (PWI) on the Geotail spacecraft. About 150 reconnection events with WFC data available are selected, and approximately 10 thousands of ESW waveforms are picked up by hands for statistical study. The ESWs are observed near diffusion region and near the plasma sheet boundary layer (PSBL). Two kinds of waveforms of ESWs are observed: bi-polar and tri-polar pulses. It is found that the pulse width of the ESWs is in the order of 1–5 ms and the peak-to-peak amplitude is in the order of 0.1–5 mV/m. The amplitudes of ESWs are larger in the near-earth tail region than that in deep tail region. ESWs have been observed with or without guide magnetic field 〈By〉. The characteristics of ESWs in different reconnection region and under different strength of guild magnetic field, their possible generation mechanism will be discussed.