基于推力器的组合航天器质量特性辨识方法研究

组合航天器的质量特性辨识对提高其姿态轨道控制的精度和快速性有至关重要的作用。对基于推力器的总质量、质心位置和惯量矩阵的在轨辨识进行了研究。基于推力作用下的平动方程可得到质心位置和总质量的耦合辨识方程,基于转动方程可得到转动惯量和质心位置的耦合辨识方程,通过对角速度和线加速度进行多次采样,利用最小二乘法求解这2类辨识方程可完成总质量、质心位置和惯量矩阵的在轨辨识。基于上述辨识原理,提出一种闭环稳定的解耦质量特性辨识方法,通过设计合适的推力器工作策略,实现总质量、质心位置和惯量矩阵的解耦辨识,并采用一种不依赖于转动惯量的控制算法,使组合航天器的姿态在辨识结束后恢复到稳定状态。仿真表明,采用闭环稳定的解耦质量特性辨识方法,可保证组合航天器在推力器激励后的姿态稳定性。在仿真采用的动力学干扰、推力器误差和敏感器误差下,总质量、质心位置和惯量矩阵的辨识精度可达到10-3量级。     

破片式反导导弹引战配合仿真与效率计算

为研究破片式反导导弹的引信、战斗部、弹目交会参数和背景干扰等对引战配合效率的影响,构建了超低空反导导弹引战配合仿真与效率计算工作平台,给出仿真及效率计算模型。在不同导弹、目标和背景干扰等参数条件下,模拟导弹的引战配合过程并计算其效率,获得了引信启动点散布、延迟时间、战斗部破片初速、飞散角、脱靶量以及背景干扰等系统参数对导弹引战配合效率的影响规律。     

基于DPSA的几种全极化RWR前端升级方案

现代高技术战争条件下，电子战任务和电磁环境中威胁信号形式变得更加多样复杂，要求电子战支援系统（ESM）天线传感器能够接收和检测各种不同极化的威胁信号，即具有全极化接收能力。本文首先简要的介绍了一种性能优良的天线一双极化曲折天线（DPSA），然后提出了利用单个双级化曲折天线，将现有机载雷达告警接收机升级为全极化接收机系统的四种解决方案，其中重点介绍了基于极化组合/分解思想的第四种方案。     

深空通信天线组阵关键技术及其发展趋势

天线组阵是未来深空通信中的重要发展方向之一。本文介绍了天线组阵的发展历程,重点讨论了组阵中的关键技术,包括阵址选择、阵元口径和数量设计、阵构型设计以及信号处理的方法,分析了上述技术对组阵性能的影响。最后,探讨了天线组阵的发展趋势。
     

基于产学研模式的飞机机务维修实训平台建设

目的探索构建校内生产性实训基地;方法以飞机结构腐蚀与控制实训平台的建设为例;结果阐述校内实现以产学研相结合模式来进行实训平台建设;结论对其它机务维修专业课程的实训平台建设起到引导的作用。     

Data fusion algorithm based on state and attribute parameter

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一类基于四面体组合单元的模块化构架式可展开天线机构

针对现有基于四面体单元的构架式天线机构结构复杂、收拢率低、运动副数量多等问题，基于3RR-3RRR四面体组合单元和基于3RR-3URU四面体对称组合单元分别提出了两种新型模块化可展结构。以3个组合单元组成的模块化结构为分析对象，首先，详细介绍了模块化结构的组成及虎克铰轴线布置，并利用组合单元本身的自由度数目及性质，采用拆杆-等效-复原的思想，应用螺旋理论和G-K公式分别对提出的两种模块化结构进行了自由度分析，得到了自由度数目及性质。其次，应用Adams动力学仿真软件对两种模块化结构进行运动仿真，仿真结果验证了自由度分析的正确性。以完全展开和完全收拢时机构所占的空间体积比值表征该机构的收拢率，计算现有基于四面体单元的非模块化机构与提出的模块化机构的收拢率。最后，对比分析非模块化机构与模块化机构的自由度数目、运动副数目及收拢率。分析结果表明，基于3RR-3URU四面体对称组合单元的模块化结构既能实现较大收拢率，自由度及运动副数目也相对减少，且组成大型天线时杆件类型较少。研究结果为该类模块化构架式可展天线结构的设计与分析提供一定理论依据。     

基于试验的电动舵机模型辨识

目前电动舵机模型的建立基本上是基于理论的数学推导,所建立的舵机模型与实际舵机模型存在一定的误差。针对此问题,提出一种基于试验实测数据建立舵机模型的方法,搭建自动数据采集试验平台,采用组合窗法对实测数据进行频域转换,得到舵机的频率响应函数并采用非线性最小二乘法辨识舵机模型。对辨识得到的数学仿真结果与实际舵机响应比较,在频域,整个频段内幅频特性最大绝对误差1.9 dB;在时域,仿真模型跟踪实际舵机角度的最大误差1.5°,延迟时间10 ms。结果表明,基于试验数据建立的舵机仿真模型能很好地模拟实际舵机。     

Categorical Bias in Line Angle Judgments: Sex Differences and the Use of Multiple Categories

According to the Category Adjustment (CA) model, spatial estimates (e.g., of location) involve Bayesian combination across multiple, hierarchical pieces information, each weighted by its relative certainty. Recent work, though, has shown that men and women differ in terms of their certainty regarding fine-grained and categorical information in location memory. Here we demonstrate that this reflects a more general sex difference in visuospatial processing by examining bias patterns in a line angle judgment task (JLAP-15). In addition, the data suggest that multiple, hierarchical levels of categorical information influenced spatial judgments. These results imply that the hierarchical combination outlined by the CA model extends beyond two levels, and that men and women apply differential weighting to these representations.     

IDS contribution to ITRF2008

For the first time, the International DORIS Service (IDS) has produced a technique level combination based on the contributions of seven analysis centers (ACs), including the European Space Operations Center (ESOC), Geodetic Observatory Pecny (GOP), Geoscience Australia (GAU), the NASA Goddard Space Flight Center (GSFC), the Institut Géographique National (IGN), the Institute of Astronomy, Russian Academy of Sciences (INASAN, named as INA), and CNES/CLS (named as LCA). The ACs used five different software packages to process the DORIS data from 1992 to 2008, including NAPEOS (ESA), Bernese (GOP), GEODYN (GAU, GSC), GIPSY/OASIS (INA), and GINS (LCA). The data from seven DORIS satellites, TOPEX/Poseidon, SPOT-2, SPOT-3, SPOT-4, SPOT-5, Envisat and Jason-1 were processed and all the analysis centers produced weekly SINEX files in either variance–covariance or normal equation format. The processing by the analysis centers used the latest GRACE-derived gravity models, forward modelling of atmospheric gravity, updates to the radiation pressure modelling to improve the DORIS geocenter solutions, denser parameterization of empirically determined drag coefficients to improve station and EOP solutions, especially near the solar maximum in 2001–2002, updated troposphere mapping functions, and an ITRF2005-derived station set for orbit determination, DPOD2005. The CATREF software was used to process the weekly AC solutions, and produce three iterations of an IDS global weekly combination. Between the development of the initial solution IDS-1, and the final solution, IDS-3, the ACs improved their analysis strategies and submitted updated solutions to eliminate troposphere-derived biases in the solution scale, to reduce drag-related degradations in station positioning, and to refine the estimation strategy to improve the combination geocenter solution. An analysis of the frequency content of the individual AC geocenter and scale solutions was used as the basis to define the scale and geocenter of the IDS-3 combination. The final IDS-3 combination has an internal position consistency (WRMS) that is 15 to 20 mm before 2002 and 8 to 10 mm after 2002, when 4 or 5 satellites contribute to the weekly solutions. The final IDS-3 combination includes solutions for 130 DORIS stations on 67 different sites of which 35 have occupations over 16 years (1993.0–2009.0). The EOPs from the IDS-3 combination were compared with the IERS 05 C04 time series and the RMS agreement was 0.24 mas and 0.35 mas for the X and Y components of polar motion. The comparison to ITRF2005 in station position shows an agreement of 6 to 8 mm RMS in horizontal and 10.3 mm in height. The RMS comparison to ITRF2005 in station velocity is at 1.8 mm/year on the East component, to 1.2 mm/year in North component and 1.6 mm/year in height.