基于可靠性分析的立方星网络维护架构优化

立方星编队或星座构成分布式空间传感器网络，可提高立方星执行复杂空间任务的能力。然而立方星易发生故障，其故障时间不确定性也导致了传感器网络性能的不稳定，这凸显了对立方星网络进行在轨维护的重要性。考虑立方星传感器网络的功能维持问题，描述了一种网络维护架构，通过定期发射、在轨备份立方星以及时更换故障立方星，从而提高网络对单星随机失效事件的快速响应与恢复能力。建立了该架构的运行成本模型，包括固定成本、储存成本和短缺成本。收集整理了真实的立方星寿命数据，并使用最大化拟合优度参数估计方法得到最优立方星寿命的随机模型。采用基于蒙特卡罗仿真的遗传算法优化备用立方星的补给时刻和补给数量，在备份成本与系统性能下降所带来的损失之间进行权衡，使得系统的综合收益最优。     

An optimal selection of probability distribution functions for unsupervised land cover classification of PALSAR-2 data

Different types of classification techniques are available in the literature for the classification of Synthetic Aperture Radar (SAR) data into various land cover classes. Various SAR images are available for land cover classification such as ALOS PALSAR (PALSAR-1, PALSAR-2), RADARSAT and ENVISAT. In this paper, we have attempted to explore probability distribution function (pdf) based land cover classification using PALSAR-2 data. Over 20 different statistical distribution functions are analyzed for different classes based on statistical parameters. Probability distribution functions are selected based on Chi-squared goodness of fit test for each individual class. A decision tree based classifier is developed for classification based on the selected pdf functions and its statistical parameters. The proposed classification approach has an accuracy of 83.93%.     

单人制机组资源管理(SRM)的训练

针对SRM的背景和基本概念进行了分析和介绍,探讨了飞行员初始飞行训练中SRM的组成、训练方法和评估要点,为飞行员培养中SRM能力的训练和应用奠定了基础。     

嵌入式大气数据测量系统技术研究进展

针对高超声速飞行器大气数据测量问题，对嵌入式大气数据测量系统(FADS)技术研究背景、发展历程、国内外研究现状等进行了概括。重点围绕FADS关键技术、FADS解算算法及面向FADS/INS组合测量系统信息融合算法方面，对FADS技术进行了深入的剖析。最后，展望了FADS技术未来的发展方向及应用前景。     

Nonlinear filtering for sequential spacecraft attitude estimation with real data: Cubature Kalman Filter,Unscented Kalman Filter and Extended Kalman Filter

This article compares the attitude estimated by nonlinear estimator Cubature Kalman Filter with results obtained by the Extended Kalman Filter and Unscented Kalman Filter. Currently these estimators are the subject of great interest in attitude estimation problems, however, mostly the Extended Kalman Filter has been applied to real problems of this nature. In order to evaluate the behavior of the Extended Kalman Filter, Unscented Kalman Filter and Cubature Kalman Filter algorithms when submitted to realistic situations, this paper uses real data of sensors on-board the CBERS-2 remote sensing satellite (China Brazil Earth Resources Satellite). It is observed that, for the case studied in this article, the filters are very competitive and present advantages and disadvantages that should be dealt with according to the requirements of the problem.     

LaBr3(Ce)元件破损在线监测关键核素确定及效率校准

常用的元件破损在线监测方法受外在因素影响较大，以γ能谱中关键裂变产物核素比活度进行在线定量分析是一种可靠的元件破损监测方法。针对新型LaBr₃(Ce)元件破损监测仪，设计了元件破损模拟实验，对逸出的裂变产物采用HPGe和LaBr₃(Ce)探测器进行了对比测量。通过不同冷却时间γ能谱的核素分析，确定了¹³⁵Xe，⁸⁸Kr，¹³⁸Xe，⁸⁸Rb，¹³⁸Cs等可作为LaBr₃(Ce)元件破损γ能谱监测的关键核素。同时，制备了覆盖能量范围(250～2 400)keV，含⁶⁰Co，¹³⁷Cs，¹³³Ba；²⁴¹Am，¹⁵²Eu；¹⁰⁹Cd，⁸⁸Y，⁵⁷Co及²⁴Na的4组放射性标准溶液，在建立的效率校准系统上，校准了LaBr₃(Ce)在线监测仪的效率。在反应堆一次异常情况分析中，已校准的LaBr₃(Ce)元件破损监测仪对关键核素的现场分析结果与HPGe的取样分析结果一致，表明效率校准结果准确，校准方法可靠。     

An assessment of semi-analytical models based on the absorption coefficient in retrieving the chlorophyll-a concentration from a reservoir

Monitoring chlorophyll-a (Chl-a) concentrations in inland waters is crucial for water quality management, since Chl-a is a proxy for phytoplankton biomass and, thus, for ecological health of a water environment. Chl-a concentration can be retrieved through the inherent optical properties (IOPs) of a water system, which, in turn, can be remotely sensed obtained. Quasi-analytical algorithm (QAA), originally developed for ocean waters, can also retrieve IOPs for inland waters after re-parameterizations. This study is aimed at assessing the performance of sixteen schemes composed by QAA original and re-parameterized versions followed by models that use absorption coefficients as inputs for estimating Chl-a concentration in Ibitinga reservoir, located at Tietê River cascading system, São Paulo State, Brazil. It was verified that only QAA_V5 based schemes were able to obtain reasonable estimates for image data and that by four models tested presented similar and acceptable results for QAA_V5 outputs. The best model were applied to a Ocean and Land Colour Instrument (OLCI) image. Light absorption in the reservoir showed to be dominated by colored dissolved organic matter (CDOM), and wide spatial and temporal variability of optical and water quality properties was observed.     

试论企业变化管理体系的要素与构建

探讨了变化与企业变化管理的内涵,论述了企业变化管理体系的构成要素与构建原则,提出了企业变化管理体系的模型——＂C＂模型,阐述了企业变化管理体系构建的步骤及方法。     

Exponent及Gauss型遥测数据建模初始化算法

在对某大型航天电子设备的遥测数据建模时,经常遇到含有指数类变化规律的数据,对其进行建模可以为研究设备性能的变化规律、实际与设计的差异等提供手段。针对有指数变化趋势的遥测数据,采用Exponent模型、Gauss模型对遥测数据建模,给出了这种数据模型的表达式,研究了2种模型的参数初始化算法。通过数值实验说明模型参数初始化算法的有效性,为后续利用最优化理论求解模型精确参数提供了良好的初试点。     

飞机健康状况量化分析方法浅析

提出与飞机健康状况相关的事件参数、风险参数的概念，具体阐述了建立量化模型的思路和方法。该方法简单可靠，具有较强的可扩展性，可为飞机的技术派遣提供决策支持。