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181.
Capturability of the pure proportional navigation (PPN) guidance law against a target executing bounded piecewise continuous time-varying manoeuvres is investigated. A qualitative analysis is carried out to obtain a set of sufficient conditions for capture defined on the engagement parameters and initial conditions. These conditions are significantly less restrictive than the ones obtained previously by others using the Lyapunov method. It is shown that the actual capture region for time-varying target manoeuvres, obtained by using the conditions derived, is much larger than that obtained from the Lyapunov technique. We also show that though a bounded tine varying target manoeuvre does change the constant target manoeuvre capture region to some extent, it does not reduce it drastically. Further, we show that the worst case capture region is obtained when the target executes a constant manoeuvre equal to the bound on the manoeuvre level. Some bounds on the missile lateral acceleration are also obtained for certain regions in the engagement plane. These results are generalizations and extensions of existing results on the capturability of the PPN guidance law against targets executing constant or time-varying target manoeuvres 相似文献
182.
183.
V. A. Grigoriev 《Space Science Reviews》1989,49(1-2):151-155
The scintillation time-of-flight triggering system of the Gamma-1 gamma-ray telescope provides for both the time-of-flight discrimination and the pulse height discrimination of the secondary particles. The paper gives some experimental results for energy dependence of the instrument efficiency in 30–300 MeV energy range for different trigger logics. 相似文献
184.
185.
Moyer L.R. Morgan C.J. Rugger D.A. 《IEEE transactions on aerospace and electronic systems》1989,25(4):584-587
An exact expression for the bistatic resolution-cell area (A B) is developed for the special case in which either the transmit or receive antenna has a broad azimuth beamwidth or is omnidirectional. Quantitative examples are presented to illustrate the variation of A B with location. A comparison is made with the performance of a commonly used approximation formula 相似文献
186.
Krishna M. V. Apparao 《Space Science Reviews》1994,69(3-4):255-329
Observations of X-ray emission from Be star/X-ray binaries are reviewed. Some optical characteristics of these binaries are also presented. Theoretical aspects pertaining to the X-ray emissions are given. 相似文献
187.
Parameters of expanding magnetic loops and arches and of mass flows generated by them in the corona have been computed in a 1D two-fluid approximation. Two possible trigger mechanisms of the coronal transients have been considered: (i) sudden increase of the background magnetic field strength, and (ii) heating and compression plasma inside these magnetic structures. We discuss the formation of shock waves and their dependence on dynamics and geometry of the magnetic structures. 相似文献
188.
The nonlinear modeling and analysis of dc-dc converters has been done by averaging and discrete-sampling techniques. The averaging technique is simple, but inaccurate, as the modulation frequencies approach the theoretical limit of one-half the switching frequency. The discrete technique is accurate even at high frequencies, but is very complex and cumbersome. An improved model is developed by combining the aforementioned techniques. This new model is easy to implement in circuit and state variable forms and is accurate to the theoretical limit. 相似文献
189.
Jovanovic M.M. Lee F.C. Chen D.Y. 《IEEE transactions on aerospace and electronic systems》1986,(2):138-145
Reverse-bias safe operating area (RBSOA) of high-power Darlington transistors is characterized using a 120 A/1000 V nondestructive reverse-bias second breakdown tester designed and fabricated at Virginia Polytechnic Institute and State University. Elaborate RBSOA characteristics are generated with different forward/reverse base drives and collector current levels. The effects of elevated case temperature and second-base drive on RBSOA of four-terminal Darlington devices are also discussed. 相似文献
190.
J. P. Cox J. C. Wheeler C. J. Hansen D. S. King A. N. Cox S. W. Hodson 《Space Science Reviews》1980,27(3-4):529-535
The radial pulsations of very luminous, low-mass models (L/M 104, solar units), which are possible representatives of the R CrB stars, have been examined. These pulsations are extremely nonadiabatic. We find that there are in some cases at least one extra (strange) mode which makes interpretation difficult. The blue instability edges are also peculiar, in that there is an abrupt excursion of the blue edge to the blue for L/M sufficiently large. The range of periods of the model encompasses observed periods of the Cepheid-like pulsations of actual R CrB stars. 相似文献