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排序方式: 共有1028条查询结果,搜索用时 375 毫秒
441.
Gillmann Cedric Way M. J. Avice Guillaume Breuer Doris Golabek Gregor J. Höning Dennis Krissansen-Totton Joshua Lammer Helmut O’Rourke Joseph G. Persson Moa Plesa Ana-Catalina Salvador Arnaud Scherf Manuel Zolotov Mikhail Y. 《Space Science Reviews》2022,218(7):1-21
Space Science Reviews - The BepiColombo Environment Radiation Monitor (BERM) on board the European Space Agency’s Mercury Planetary Orbiter (MPO), is designed to measure the radiation... 相似文献
442.
A study is made to define a procedure of cooperative processing of goniometric and range difference measurements in multilateral system of passive radiolocation. As a result, we worked out the computational algorithms, which implement this procedure. The accuracy characteristics are estimated. 相似文献
443.
V. A. Afanas’ev G. L. Degtyarev V. I. Kiselev A. S. Meshchanov 《Russian Aeronautics (Iz VUZ)》2016,59(3):324-330
We resolve a problem how to control the longitudinal angular motion of flight vehicles (FV) having a system to displace the center of mass in the transverse direction. A structure is determined and a control law is established to start up and shutdown the engines. Formulas to determine the control parameters are obtained. 相似文献
444.
In practice, some sensors of aircraft engines naturally fail to obtain an acceptable measurement for control propose, which will severely degrade the system performance and even deactivate the limit protection function. This paper proposes an adaptive strategy for the limit protection task under unreliable measurement. With the help of a nominal system, an online estimator with gradient adaption law and low-pass filter is devised to evaluate output uncertainty. Based on the estimation result, a sliding mode controller is designed by defining a sliding surface and deriving a control law. Using Lyapunov theorem, the stability of the online estimator and the closed-loop system is detailedly proven. Simulations based on a reliable turbofan model are presented, which verify the stability and effectiveness of the proposed method. Simulation results show that the online estimator can operate against the measurement noise, and the sliding controller can keep relevant outputs within their limits despite slow-response sensors. 相似文献
445.
The results of numerical studying the influence of inertially deposited particles of the condensed phase on the efficiency
of a gas screen in a supersonic dispersed flow are presented. The possibility of realizing the Leont’ev paradox on the adiabatic
surface region streamlined by a supersonic dispersed flow, involved in attaining the temperature of the surface being protected
smaller than the coolant temperature on the permeable section of screen formation is specified. 相似文献
446.
A technique for constructing the observers to evaluate a linear combination of state variables is considered. We propose an algorithm for analytical synthesis of the minimum-order functional observers based on the nondegenerate transformation of the object model in the state space using the matrix canonization technology. The applicability limits of the technique and the conditions of problem solvability are defined. 相似文献
447.
V. N. Kuril’chik 《Cosmic Research》2011,49(6):500-503
The auroral kilometric radio emission (AKR) is the most powerful sporadic radio emission of the terrestrial magnetosphere.
It was discovered in 1965 by Soviet scientists in the experiment onboard the Electron-2 satellite [1]. The AKR still continues to stay an object of a large interest and detailed study (see, for example, a review
by Gurnett [2]). The mechanism of cyclotron maser instability proposed by Wu and Lee [3] is a commonly accepted mechanism
of AKR generation. We have demonstrated the presence of powerful AKR simultaneously in both hemispheres of the Earth in the
period from August 1995 to August 1997, including summer-winter periods, on particular examples of registration of this emission
in [4] where the directivity and mechanism of the emission were studied. Since in that period AKR was observed in the vicinity
of perigees of the satellite orbit in both hemispheres almost at every orbit (3.8 days), we have a possibility to trace in
more detail the changes in the emission power from one orbit to another in 1996 during a deep minimum of solar activity. 相似文献
448.
I. V. Bychkov V. A. Voronov E. I. Druzhinin R. I. Kozlov S. A. Ul’yanov B. B. Belyaev P. P. Telepnev A. I. Ul’yashin 《Cosmic Research》2014,52(2):145-152
The paper presents the second part of the results of search studies for the development of a combined system of high-precision stabilization of the optical telescope for the designed Spectr-UF international observatory [1]. A new modification of the strict method of the synthesis of nonlinear discrete-continuous stabilization systems with uncertainties is described, which is based on the minimization of the guaranteed accuracy estimate calculated using vector Lyapunov functions. Using this method, the synthesis of the feedback parameters in the mode of precise inertial stabilization of the optical telescope axis is performed taking the design nonrigidity, quantization of signals over time and level, and errors of orientation meters, as well as the errors and limitation of control moments of executive engine-flywheels into account. The results of numerical experiments that demonstrate the quality of the synthesized system are presented. 相似文献
449.
Two criteria for the applicability of a gas-dynamic approximation of continuous medium to describing the dispersion of combustion products of rocket propellants at high altitudes are formulated. Related numerical estimates are given for different launch vehicles and one upper stage with fairly extended boost phases. The use of a continuous medium approximation is shown to have a clear altitude restriction. 相似文献
450.
刘昕 《西安航空技术高等专科学校学报》2008,26(3):6-8
当代大型喷气式客机的机载辅助动力装置(APU)是飞机中一个重要系统,为了提高飞机维修的经济性、减少延误,开发出了APU状态监控和故障诊断系统。该系统有极大的创新性,为飞机系统的状态监控故障诊断领域奠定了基础。 相似文献