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311.
C. Marchal 《Acta Astronautica》1979,6(9):1153-1161
Problems of Hamiltonian Mechanics can generally be simplified by some Von Zeipel transformations which reduce the influence of short period parameters and lead to very slowly variable functions: the “quasi-integrals”; however these transformations are implicit and then difficult to use.An explicit construction of the quasi-integrals is presented here and is used to integrate the motion of an artificial satellite perturbed by the zonal harmonics of the Earth gravitational potential; the quasi-integrals are also used to obtain informations on the stability of natural satellites, i.e. lower bounds on the duration of escape or capture. 相似文献
312.
313.
Exact and approximate baseband models of the DeLange frequency-modulated oscillator are derived. Exact and approximate baseband distortion equalizers, that may be used to predistort the modulation voltage so that the distortion in the output phase of the oscillator is removed, are also given. 相似文献
314.
The effect of modulation nonlinearity on the range response of FM radars with harmonic processing and ?triangle? modulation is derived. The nonlinearity may be desirable or undesirable; that is, the sidelobe level of the range response may be decreased or increased depending on the shape and amount of nonlinearity. The results of this paper may be used to predict the actual range laws of existing ?linear? FM radars; or, alternately, to specify the desired amount of modulation nonlinearity for new FM radars so that superior sidelobe suppression can be realized. 相似文献
315.
A UHF ?true logarithmic IF? which yields a carrier output proportional in amplitude to the logarithm of the carrier input has been constructed. Although this ?true? form has been known for a number of years, it appears to have been neglected in development. Good performance has been obtained over a 60-dB input signal range with rise and fall times of 2 ns per 20 dB. A high-level, detected dc coupled output without the use of any dc amplifier is obtained. Coherent signal processing of the output carrier is possible, and other important advantages to this type of logarithmic IF are described. 相似文献
316.
A detailed inaccuracy and sensitivity analysis of a long-distance air pollution detection system, using a laser measuring the resonance absorption of polluting molecules, is introduced. The noise and the dynamic range of the radiation detectors used, the atmospheric inhomogeneities, and the atmospheric propagation losses of the electromagnetic radiation are considered. In addition, the best measuring path length as a function of a molecule density and atmospheric transparency and irregularity is discussed. 相似文献
317.
Robert G. Stone 《Space Science Reviews》1973,14(3-4):534-551
The remote sensing of low frequency nonthermal radio emission is the astronomy of field and particle phenomena. Observations conducted from space lead to information about the composition and dynamic processes occurring in planetary magnetospheres as well as within the interplanetary and interstellar medium. The potential of this technique is demonstrated by considering observations obtained from Earth orbit missions.This is one of the publications by the Science Advisory Group. 相似文献
318.
319.
Joseph F. Dolan 《Space Science Reviews》1970,10(6):830-868
The variability of the X-ray spectrum of the discrete source Cyg XR-1 (α = 19h 56m δ = +35°.1) is reviewed. The variations observed in the energy region accessible to balloon borne detectors (energies greater
than 20 keV) can be explained by assuming them to be caused by the eclipsing properties of a binary system. It is suggested
that the system is composed of a source of small angular extent having a spectrum similar to that of a black body at approximately
1.5 × 108 K (kT= 12.5 keV) and a non X-radiating companion which eclipses it at intervals of 2.9850 days. The system would be surrounded
by an X-radiating plasma whose photon flux between 1 and 100 keV can be approximated by a power law spectrum whose exponent
is — 1.7. 相似文献
320.
The radar cross section of a flat plate has a sin x/x lobe structure. If a synthetic-array radar flies past the plate the resulting image is dependent upon what part of this lobe structure is sampled. When the plate is parallel to the flight path, the image is a line as wide as the plate. If the plate is not parallel, only the discontinuities at the ends of the plate are visible in the image. 相似文献