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91.
对DATH在复合改性双基推进剂中应用及配装浇 出工艺制DATH-CMDB推进剂药柱过程中出现的较强固化放气问题做了探讨,得出了若干结论。  相似文献   
92.
Capturing a non-cooperative space target is a tremendously challenging research topic. Effective acquisition of motion information of the space target is the premise to realize target capture. In this paper, motion prediction of a free-floating non-cooperative target in space is studied and a motion prediction algorithm is proposed. In order to predict the motion of the free-floating non-cooperative target, dynamic parameters of the target must be firstly identified (estimated), such as inertia, angular momentum and kinetic energy and so on; then the predicted motion of the target can be acquired by substituting these identified parameters into the Euler’s equations of the target. Accurate prediction needs precise identification. This paper presents an effective method to identify these dynamic parameters of a free-floating non-cooperative target. This method is based on two steps, (1) the rough estimation of the parameters is computed using the motion observation data to the target, and (2) the best estimation of the parameters is found by an optimization method. In the optimization problem, the objective function is based on the difference between the observed and the predicted motion, and the interior-point method (IPM) is chosen as the optimization algorithm, which starts at the rough estimate obtained in the first step and finds a global minimum to the objective function with the guidance of objective function’s gradient. So the speed of IPM searching for the global minimum is fast, and an accurate identification can be obtained in time. The numerical results show that the proposed motion prediction algorithm is able to predict the motion of the target.  相似文献   
93.
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   
94.
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   
95.
某型飞机起落架故障诊断专家系统设计研究   总被引:2,自引:0,他引:2  
给出了飞机起落架故障诊断专家系统的构成、体系结构以及功能,引入了正向推理、不精确推理两种推理机制,研究了基于数据库技术的知识库构建方法,并用此构建方法完成了软件测试.仿真试验表明,应用此系统可以提高起落架故障智能诊断的效率和准确性,具有较强的实用性.  相似文献   
96.
Gaseous cavity at the base of an underwater projectile   总被引:1,自引:0,他引:1  
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   
97.
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   
98.
阐述了实验室认可前应做好的基础工作,提出了实验室认可后进一步完善的建议。  相似文献   
99.
崔德刚  吴广茂 《航空学报》1993,14(12):583-587
 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   
100.
田志学  李军  谭金安 《航空学报》2001,22(4):373-375
 回顾了成本管理理论的发展,分析了目标成本管理和作业成本管理的共性和不同之处以及两者集成的可行性,从理论上建立了目标成本管理与作业成本管理集成的成本管理体系,并对该成本管理体系实施的保证机制进行了探讨。  相似文献   
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