利用非GEO卫星进行地面站时间同步研究

根据地球静止轨道（GEO）卫星转发同步信号的双向时间比对法实现站间时间同步的基本原理,提出了利用拟合非GEO卫星转发信号的伪距实现时间同步的新方法。拟合伪距法消除了传播路径延迟和只能使用GEO卫星作为信号转发器的限制,扩大了双向时间比对的应用范围。仿真结果表明：该法有较高的精度,满足工程要求。     

主成份估计的特征根因子筛选方法

线性回归模型的主成份估计具有模型紧致和减弱病态的作用,并提高参数估计效果,但是如何筛选特征根却是主成份估计的重要问题。本文找到了主成份估计的特征根与残差平方和之间的确定关系,并根据模型拟合优度和减弱测量随机噪声对参数估计的影响,提出主成份估计筛选特征根的准则。由于特征根与残差平方和具有确定关系,使用这个准则就极为方便,它既可以选到最优组合,又大大减少了计算量,这就具有实际使用价值。     

基于等效介质理论的电磁晶体带隙分析

根据等效介质理论的基本原理和一维电磁晶体的矩量法分析模型,将二维方格子电磁晶体等效为一维结构,用等效介电常数求解公式求解不同周期波长比和填充率的等效介电常数,由一维电磁晶体的矩量法分析模型求解二维电磁晶体的带隙结构。分析结果表明：该等效模型适于分析小填充率的二维方柱电磁晶体。     

基于接收机钟差的GPS完好性自主检测算法

传统的基于最小二乘法和奇偶矢量的接收机自主完好性检测（Receiver Autonomous Integrity Monitoring, RAIM）算法均是利用冗余观测量进行一致性检验实现的,其检测统计量均由伪距残差构造得到。本文采用接收机钟差作为RAIM算法的判据,基本思想是根据钟差历史解算值建立接收机钟差二次多项式模型,从而得到当前时刻的钟差预测值。同时解算当前时刻的钟差值,将这两者之差与钟差门限值进行比较来判断系统当前时刻是否存在故障。本文首先分析了伪距偏移量对接收机钟差的影响,然后给出确定钟差门限值的方法。结合用户解算位置和接收机钟差利用子集比较法实现了故障识别的功能。因本文给出的故障检测算法不是基于冗余观测量的,故该方法在四颗可见星下就可进行故障检测,与传统的RAIM算法相比降低了RAIM算法对可见星个数的要求,该点在实验部分进行了仿真验证。另外还对可用星多于四颗的基于接收机钟差的RAIM算法进行了故障检测和故障识别部分的仿真,验证了本文方法的可行性。
     

高速采样测量数据处理方法研究

探讨在新一代高精度测速体制下,外测数据原有处理方法应用到高采样率数据时的缺陷,提出将原始采样数据分段、分层进行多次处理,结合二步最小二乘、等距样条拟舍和区间长度自适应的时间多项式中心平滑技术,可降低每次处理的数据量,并逐步滤除周期噪声与色噪声,提高了处理结果的精度。     

基于FAA25-131修正案的飞机告警系统适航问题分析

FAA25.1322规定了飞机警告灯、戒备灯和提示灯颜色的使用要求。FAA25-131修正案在原有14CFR25.1322条款的基础上,对飞行显示与机组告警系统提出了新的要求。本文对该修正案进行分解与分析,明确了修正案要求的重点考虑事项,简单、客观地呈现了与这些条款项关联的技术问题的矛盾性争辩过程,进行了基于型号研制实践的符合性方法总结,为验证民用飞机飞行显示与机组告警系统对FAR25-131修正案的符合性提供了有效途径,具有工程实践意义。     

鸭翼的雷达散射截面影响研究

针对鸭翼对鸭式布局战斗机整机的雷达散射截面（RCS）影响进行了较详细的研究与分析。首先，分析了鸭翼的散射机理，然后运用多层快速多极子方法（MLFMM）进行特定模型的整机外形RCS计算，通过鸭式布局和常规布局的RCS对比，分析了鸭翼散射对整机RCS的影响，包括鸭翼偏转状态下对整机的影响。然后，通过试验方法研究了鸭翼边缘散射和对缝散射的影响以及相应的抑制措施。研究结果表明，对鸭翼散射进行抑制或消除之后，鸭式布局完全可以应用于高隐身飞机的布局设计，其隐身性能与常规布局相当。最后，总结得出鸭翼隐身设计的指导性原则。     

Correlation-weighted least squares residual algorithm for RAIM

The Least Squares Residual (LSR) algorithm, one of the classical Receiver Autonomous Integrity Monitoring (RAIM) algorithms for Global Navigation Satellite System (GNSS), presents a high Missed Detection Risk (MDR) for a large-slope faulty satellite and a high False Alarm Risk (FAR) for a small-slope faulty satellite. From the theoretical analysis of the high MDR and FAR cause, the optimal slope is determined, and thereby the optimal test statistic for fault detection is conceived, which can minimize the FAR with the MDR not exceeding its allowable value. To construct a test statistic approximate to the optimal one, the Correlation-Weighted LSR (CW-LSR) algorithm is proposed. The CW-LSR test statistic remains the sum of pseudorange residual squares, but the square for the most potentially faulty satellite, judged by correlation analysis between the pseudorange residual and observation error, is weighted with an optimal-slope-based factor. It does not obey the same distribution but has the same non-central parameter with the optimal test statistic. The superior performance of the CW-LSR algorithm is verified via simulation, both reducing the FAR for a small-slope faulty satellite with the MDR not exceeding its allowable value and reducing the MDR for a large-slope faulty satellite at the expense of FAR addition.     

Closed form algorithm of double-satellite TDOA+AOA localization based on WGS-84 model

In this paper, we consider the double-satellite localization under the earth ellipsoid model of the Wideband Geodetic System(WGS-84) using the Time Difference of Arrival(TDOA)and the Angle-of-Arrival(AOA).Several closed-form solution algorithms via the pseudolinearization of the measurement equations are presented to efficiently estimate the location.These algorithms include the Weighted Least Squares(WLS), the Constrained Total Least Squares(CTLS), and the Taylor-Series Iteration(TSI).Performance comparison of the proposed methods with the Cramér-Rao Lower Bound(CRLB) in the simulation is shown to demonstrate that the proposed algorithms are feasible and have stable performance.     

Catching spiral – S0 transition in groups. Insights from SPH simulations with chemo-photometric implementation

We are investigating the co-evolution of galaxies within groups combining multi-wavelength photometric and 2D kinematical observations. Here we focus on S0s showing star formation in ring/arm-like structures. We use smooth particle hydrodynamical simulations (SPH) with chemo-photometric implementation which provide dynamical and morphological information together with the spectral energy distribution (SED) at each evolutionary stage. As test cases, we simulate the evolution of two such S0s: NGC 1533 and NGC 3626.