G. D. Fleishman  A. V. Stepanov  Yu. F. Yurovsky 《Space Science Reviews》1994,68(1-4):205-210

The unusual event of November 17, 1991 07:04 UT, observed at 2.5 and 2.85 GHz, is analysed. The event reveals the sophisticated superfine time structure including sudden reductions and quasi-periodic pulsations. We shown that the sudden reductions (30–100 ms) can be driven by upward injected 100 keV electron beams filling the losscone of the coronal magnetic trap. The nonlinear oscillations of Langmuir waves provide the best fit for the pulsation observed. A reduced steady-state level of the pulsation phase is connected with quasi-continuous injection of electrons. The physical parameters of the radio source are found for the event.  相似文献   

    

M. Abada-Simon  A. Lecacheux  T. S. Bastian  J. A. Bookbinder  G. A. Dulk 《Space Science Reviews》1994,68(1-4):291-292

We report the first millimetric detections of the magnetic cataclysmic variable AE Aquarii, accompanied by contemporaneous microwave observations. These data show that the time-averaged spectrum is well fit by a power-law which extends to mm wavelengths. We suggest that the spectrum is consistent with that expected from a superposition of flare-like events.  相似文献   

    

Rotman  S.R. Tidhar  G. Kowalczyk  M.L. 《IEEE transactions on aerospace and electronic systems》1994,30(1):81-91

The problem of calculating an effective contrast for diffused targets in visual scenery is addressed. The effect of local variations of intensity in the vicinity of the target is modeled by considering the distribution of the intensity of the edges. The effect of global clutter is discussed from the vantage point of selecting the best model for background scenery. Generalized contrast measures are described and applied to real scenes  相似文献   

    

G. M. Simnett 《Space Science Reviews》1994,70(1-2):69-75

It is suggested that the energy input for explosive events in the transition zone comes from precipitating ions, typically of energies of a few×10² keV/nucleon, accelerated in the high corona. The energetics of the process are discussed, together with implications for coronal heating.  相似文献   

    

Landis  G.A. 《Aerospace and Electronic Systems Magazine, IEEE》2000,15(1):17-21

The surface of Mars is an environment significantly different from both the surface of the Earth and from orbit. Solar cell performance is the major constraint on the landing site latitude, on science operations, and on how long during each day and during which Mars seasons a spacecraft can operate. This article examines what we know about the environment of Mars and how it affects the selection of solar cells for Mars surface operation  相似文献   

    

Bataineh  S. Robertazzi  T.G. 《IEEE transactions on aerospace and electronic systems》1997,33(4):1189-1198

Ultimate performance limits to the aggregate processing speed of networks of processors that are processing a divisible job are described. These take the form of either closed-form expressions or numerical procedures to calculate the equivalent processing speed of an infinite number of processors. These processors are interconnected in either a linear daisy chain with load origination from the network interior or a tree topology. The tree topology is particularly general as a natural way to perform load distribution in a professor network topology with cycles (e.g., hypercube, toroidal network) is to use an embedded spanning tree. Such limits on performance are important as they provide an ideal baseline against which to compare the performance of finite configurations of processors.  相似文献   

    

Ivensky  G. Gulko  M. Ben-Yaarov  S. 《IEEE transactions on aerospace and electronic systems》1997,33(1):53-63

A novel topology, current-fed multiresonant dc-dc converter (CF-MRC) was studied theoretically and experimentally. The new topology differs from previously described current-fed push-pull parallel-resonant topologies in the fact that the output is coupled to the current of the resonant inductor and in the addition of a second capacitor across the transformer. The main features of the proposed converter are an inherent protection against a short and open circuit at the output, a high voltage gain and zero voltage switching (ZVS) over a large range of output voltage. These characteristics make it a viable choice for applications, such as a high voltage capacitor charger, that require controllable current sourcing over a wide output voltage swing.  相似文献   

    

E. G. Podruzhin  A. R. Zagidulin 《Russian Aeronautics (Iz VUZ)》2017,60(3):342-348

The paper describes a mathematical model of drop tests on the landing gear of the Ka-62 helicopter. The model is formulated using the multibody system simulation procedure based on the Lagrange equations of the first kind.  相似文献   

    

Buck  G.J. 《IEEE transactions on aerospace and electronic systems》1969,(4):606-610

A phase monopulse antenna system can be used for the high accuracy tracking of active or passive objects in space or on earth. Far-field noise sources that are present in the background of the object being tracked will introduce an offset or bias error in the determination of the angle of incidence of the coherent sinusoidal wave received from the source. The dependency of this bias error upon the nonuniformity of the noise background or equivalently upon the asymmetry of the antenna patterns about the direction to the signal being tracked is determined. Although the variance in the measurement of the sinusoidal source direction can be reduced by increasing the post detection integration time, it is shown that the bias or offset error is unaffected by this change. In order to decrease the offset or bias error the predetection bandwidth must be reduced.  相似文献   

    

Pelletier  M. Cummins  J. Delisle  G.Y. 《IEEE transactions on aerospace and electronic systems》1977,(3):318-321

The phases of the radiation fields in a multibeam antenna are analyzed and their relations to the feed network are established. A method of phase control is proposed and applied to the case of cophasal beams radiated from an array for which the feed network is a lossless Butler matrix.  相似文献