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391.
Expressions for moving target indicator (MTI) improvement factor limitation due to pulse repetition frequency (PRF) staggering and loss of target detectability for various values of Doppler frequency in the passband are presented. It is also shown that the product of variance of stagger periods and clutter variance is an important parameter determining the performance of a staggered PRF MTI radar. 相似文献
392.
393.
The equations of motion of a momentum biased spacecraft are derived in a general form. The spacecraft is assumed to be orbiting in a near-elliptical orbit. An aerodynamic torque model which accounts for the atmospheric superrotation is assumed. The equilibrium attitude angles are obtained in terms of modified Bessel functions. Analytic expressions for the long-term motion of the momentum biased axis are derived for special cases. The analysis is applicable to the Magsat mission. 相似文献
394.
Middlebtook R.D. Kimble S.G. 《IEEE transactions on aerospace and electronic systems》1976,(2):162-172
The High Energy Astronomy Observatory (HEAO) main bus regulator contains a redundant error amplifier (REA) and a 12-section sequenced shunt transconductance amplifier (STA) in which not more than three and not less than one shunt section are in an active control mode regardless of a failure in any one of the twelve sections. The part of the work concerned with the shaping of the frequency response of the REA and STA minor feedback loops and of the teolator major feedback loop is described. Emphasis is on the application of a general design technique embodying a "design-analyze-measure iteration loop," in which a first-cut design and analysis is corrected ard improved after experimental observation of discrepancies and deficiencies. In particular, an incipient high-frequency oscillation was thereby reliably eliminated. It is demonstrated that analysis techniques involving a minimum of algebra can provide full quantitative information on an efficient and reliable system design. 相似文献
395.
There is a growing need for the scientist, engineer, and administrator to better understand the kinds of overall, across-the-board planning problems involved in the development of off-shore coastal areas. A recommended approach is to use systems analysis techniques. Principles will be set forth on maintaining and improving the quality of the ocean environment, with considerations of cost in so doing. Each proponent of an aspect of ocean technology usually believes that his field must be greatly enlarged in the near future. Along with these advances there is the likelihood of unnecessary social costs emanating from undesirable modifications of the environment. In making the analysis, an early step is to identify specific needs and appropriate roles. A next step is to lay out alternatives for achieving objectives both within a given organization and external to it. The alternatives may be appraised through their costs and benefits. But how do you make choices between goals when resources are limited? How can we gather the data, accomplish the evaluation, and do the planning that will make rational choices possible? This paper elucidates the problems involved in these kinds of questions and suggests methodology that might lead toward solutions. 相似文献
396.
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398.
Many simple radars use fact-risetime pulses, but wide bandwidth does not translate into corresponding high resolution since the spectrum is far from flat. A scheme for enhancing down- and cross-range resolution of multiple targets through a two-step partial equalization of the spectrum is illustrated by detailed computer simulation, with emphasis on the tradeoffs between resolution and signal-to-noise ratios. Three examples are treated: two equal scattering centers, two unequal scattering centers, and compound target 相似文献
399.
400.
F. M. Ipavich G. Gloeckler C. Y. Fan L. A. Fisk D. Hovestadt B. Klecker J. J. O'Gallagher M. Scholer 《Space Science Reviews》1979,23(1):93-101
We report initial measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE-1. ULECA is an electrostatic deflection — total energy sensor consisting of a collimator, deflection analyzer and an array of solid state detectors. The position of a given detector, which determines the energy per charge of an incident particle, together with the measured energy determine the particle's charge state. We find that a rich variety of phenomena are operative in the transthermal energy regime (10 keV/Q to 100 keV/Q) covered by ULECA. Specifically, we present observations of locally accelerated protons, alpha particles, and heavier ions in the magnetosheath and upstream of the Earth's bow shock. Preliminary analysis indicates that the behavior of these locally accelerated particles is most similar at the same energy per charge. 相似文献