Quantifying lunar soil composition with partial least squares modeling of reflectance

Retrieval of lunar soil composition is commonly achieved through optical remote sensing in which spectral characteristics of returned lunar samples are related to their constituents. Partial least squares (PLS) and principal component regression (PCR) were applied to the dataset characterized by the Lunar Soil Characterization Consortium (LSCC) to estimate the content of FeO, Al₂O₃ and TiO₂ in the soils. The goal of this study was to test whether the conversion of reflectance to single scattering albedo (SSA) via Hapke’s radiative transfer model is able to improve the performance of PLS and PCR. Results from PLS and PCR modeling of SSA spectra indicate that the conversion does not necessarily improve the performance of PLS and PCR, and this depends on the chemical considered, the way to select the number of optimal factors, and how the data were pretreated. The conversion failed to accommodate the large deviation of highland samples with low FeO, TiO₂ and high Al₂O₃.     

数字化技术在波音737飞机尾段制造中的应用

论述了沈阳飞机工业(集团)有限公司(简称沈飞)在新一代波音737飞机尾段上数字化技术的研究与应用,以及实施数字化技术的理念和成果。着重论述了数字传递过程、工艺、工装设计制造方面的应用。     

一种单站无源定位原理与目标跟踪算法研究

基于辐射源的信号到达方向(DOA)及其变化率信息,提出了一种对机动目标进行单站无源定位与跟踪的方法。根据建立的目标机动模型和测量方程,分别用扩展卡尔曼滤波(EKF)和修正协方差扩展卡尔曼滤波(MVEKF)算法实现对机动目标的定位与跟踪,并给出了算法模型。仿真结果表明,该法正确有效,定位精度较高、收敛速度快。     

采用单轴双太阳帆板空间站的一种姿态定向模式

采用单轴双帆板供电和单框架控制力矩陀螺(SGCMG)作为执行机构的倾斜轨道空间站,当太阳方向与轨道面夹角较大时,帆板的光照条件不易保证,为此本文针对这种类型的空间站设计了一种姿态定向模式以保证帆板的光照条件,并通过在阴影区姿态机动,利用重力梯度力矩对SGCMG进行卸载。仿真结果表明,该姿态定向模式满足太阳帆板的光照条件,重力梯度力矩卸载方法保证了SGCMG中的角动量不超出给定的范围。     

微小卫星星地数据链路层通讯协议的研究和开发

卫星和地面之间的交流通过它们之间的数据通讯来实现。为了实现星地通讯,必须选定双方都要遵守的协议。考虑到星地通信的可靠性和效率,在选择通讯协议时需遵循实用且最简单的原则。参考CCSDS的相关建议和Ax．25协议,开发了一种星地链路层通信协议。纳星一号飞行试验的运行结果表明,该协议具有较高的数据传榆效率和良好的可靠性,可以满足微小卫星的实际通信要求。     

Validation of the new trapped environment AE9/AP9/SPM at low Earth orbit

The completion of the international space station (ISS) in 2011 has provided the space research community an ideal proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the validation of radiation environmental models, nuclear transport codes and nuclear reaction cross sections. Indeed, prior measurements on the space transportation system (STS; shuttle) provided vital information impacting both the environmental models and the nuclear transport code developments by indicating the need for an improved dynamic model of the low Earth orbit (LEO) trapped environment. Additional studies using thermo-luminescent detector (TLD), tissue equivalent proportional counter (TEPC) area monitors, and computer aided design (CAD) model of earlier ISS configurations, confirmed STS observations that, as input, computational dosimetry requires an environmental model with dynamic and directional (anisotropic) behavior, as well as an accurate six degree of freedom (DOF) definition of the vehicle attitude and orientation along the orbit of ISS.     

碳纳米管气体传感器在空间站在轨检漏中的应用

空间站在轨检漏技术对维护空间站安全起着至关重要的作用。未来空间站检漏技术要求能更加快速、准确地确定微小泄漏点的位置。碳纳米管表面积大,对气体吸附反应灵敏,利用碳纳米管制备的气体传感器具有灵敏度高、响应快、重量轻、体积小、功耗低等特点,可以用于微量气体检测。据此,文章提出可以将碳纳米管气体传感器技术用于空间站的在轨检漏,并探讨了该技术在空间站检漏应用中面临的关键问题和解决方案。碳纳米管气体传感器技术的研究和发展有望提高空间站在轨检漏技术水平,为空间站的安全可靠运行提供保障。     

Accuracy and coverage of the modernized Polish Maritime differential GPS system

The DGPS navigation service augments The NAVSTAR Global Positioning System by providing localized pseudorange correction factors and ancillary information which are broadcast over selected marine reference stations. The DGPS service position and integrity information satisfy requirements in coastal navigation and hydrographic surveys. Polish Maritime DGPS system has been established in 1994 and modernized (in 2009) to meet the requirements set out in IMO resolution for a future GNSS, but also to preserve backward signal compatibility of user equipment. Having finalized installation of the new technology L1, L2 reference equipment performance tests were performed.     

A rendezvous navigation algorithm for orbit determination, based on visual measurements by space vehicle crew members

At present, various radio navigation systems are employed during the automated approach of a transport vehicle to a space station. Experience has shown that emergency situations can occur in which it is necessary to revert to manual override of the automatic approach.Such situations have indeed occurred during flight operations of the space station Mir. The crews of the transport vehicles and the Mir used manual steering more than 30 times for successful docking, and four times for approach to the station.Successful manual steering demands absolute understanding of the relative orbit parameters. The decisive task of the crew is to determine these relative parameters. This is possible using visual observations from either the transport vehicle or the station using simple and reliable instruments. This article explains the algorithm for determining the relative orbits from visual crew observations, based on similarities of relative orbit families.     

自适应光学技术在欧美激光通信地面站应用现状

自适应光学技术是提高激光通信地面站单模光纤耦合效率、增加接收信号信噪比、提升激光通信可靠性的一种重要手段。对欧美将自适应光学技术应用于激光通信地面站的情况进行了详细阐述与分析，主要内容包括自适应光学系统的组成、参数和部分实验结果，为激光通信地面站及其自适应光学系统的设计提供有益的参考。