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101.
Real-time and accurate fault detection is essential to enhance the aircraft navigation system’s reliability and safety. The existent detection methods based on analytical model draws back at simultaneously detecting gradual and sudden faults. On account of this reason, we propose an online detection solution based on non-analytical model. In this article, the navigation system fault detection model is established based on belief rule base (BRB), where the system measuring residual and its changing rate are used as the inputs of BRB model and the fault detection function as the output. To overcome the drawbacks of current parameter optimization algorithms for BRB and achieve online update, a parameter recursive estimation algorithm is presented for online BRB detection model based on expectation maximization (EM) algorithm. Furthermore, the proposed method is verified by navigation experiment. Experimental results show that the proposed method is able to effectively realize online parameter evaluation in navigation system fault detection model. The output of the detection model can track the fault state very well, and the faults can be diagnosed in real time and accurately. In addition, the detection ability, especially in the probability of false detection, is superior to offline optimization method, and thus the system reliability has great improvement. 相似文献
102.
J. Kozicka 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(1):129-137
Technical and architectural problems of a Martian base have been arised in many publications. Usually there is one solution described in detail or general classification is presented. In this paper, a recognition of low-cost solutions for Martian architecture is analyzed. The overview through various building techniques based on previous concepts of extraterrestrial architecture is summarized. Several solutions taking advantages of the shape of terrain, aiming for cost decreasing of human settlement on Mars are proposed. 相似文献
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Gaseous cavity at the base of an underwater projectile 总被引:1,自引:0,他引:1
A Dyment J.P Flodrops J.B Paquet D Dupuis D Marchand 《Aerospace Science and Technology》1998,2(8):489-504
The problem of the behavior of the gaseous cavity which is formed at the base of an underwater launched projectile is treated using different approaches. Asymptotic analysis is used to yield expressions for similarity parameters and a simplified hydrodynamic model of the initial stretching phase. A laboratory facility is described, in which launches can be simulated and analyzed by means of pressure measurements and high speed visualizations. Complete calculations are also performed using a numerical “Volume of Fluid” model solving the unsteady Navier-Stokes equations. Results from the three approaches are presented and compared during the cavity stretching phase. Finally, the thermodynamic aspects of the problem are examined. 相似文献
105.
Dmitri Nikolaevich Severov Valentina Pshennikov Alexsandr Vasilievich Remeslo 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Fronts and thermohaline structure of the Brazil–Malvinas Confluence System (BMCS) are studied from climatic data, “Marathon Exp. Leg.8, 1984” data, and Sea surface temperature (SST) data base “ds277-Reynolds” (1981–2000). The South Atlantic Central Water (SACW) is divided in two main types: tropical (TW) and subtropical water (ST). Water masses, Fronts, Inter-Frontal and Frontal Zones are analysed and classified: (a) the water masses: Tropical Low-Salinity Water, Tropical Surface Water, Tropical Tropospheric Water, Subtropical Low-Salinity Water, Subtropical Surface Water, Subtropical Tropospheric Water. T,S characteristics of intermediate, deep and bottom water defined by different authors are confirmed and completed; (b) the Inter-Frontal Zones: Tropical/Brazil Current Zone, Subtropical Zone and Subantarctic Zone; (c) the Frontal Zones: Subtropical, Subantarctic and Polar, and (d) the Fronts: Subtropical Front of the Brazil Current, Principal Subtropical Front, North Subtropical Front, Subtropical Surface Front, South Subtropical Front, Subantarctic Surface Front, Subantarctic Front and Polar Front. Several stable T–S relationships are found below the friction layer and at the Fronts. The maximum gradient of the oceanographic characteristics occurs at the Brazil Current Front, which can be any of the subtropical Fronts, depending on season. Minimum mean depth of the pycnocline coincides with the Fronts of the BMCS, indicating the paths of low-salinity shelf waters into the open ocean. In the work it is shown how to recover the horizontal and vertical thermohaline structure of waters from satellite data RSMAS SST. 相似文献
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应用数据库技术、文档管理系统和通用数据文件格式实现大型计算机辅助设计集成系统的数据管理、信息交换,在统一执行控制系统的操作下,实现程序流的运行和数据流的管理,同时为用户提供良好的用户界面,这样形成了CIEM集成系统框架。在此基础上集成了飞机设计的大量应用程序和图形软件,形成程序流和数据流,即CIEM集成系统的集成技术。 相似文献
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