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961.
962.
963.
We review the details of the glint (angular scintillation) problem in electromagnetic scattering. These results are employed to develop a statistical glint and radar cross section (RCS) target model featuring the correct glint probability density function, the correct time correlations of RCS and glint, and the correct cross correlation between RCS and glint. This model is suitable for simulation applications, and an implementation scheme for a glint/RCS signal generator is included. 相似文献
964.
Krishnamoorthy B.M. Krishnamurthy M.R. 《IEEE transactions on aerospace and electronic systems》1983,(1):103-113
Analytical investigation based on limiting nonlinear theory presented here for the asychronous performance of a slitted solid iron rotor reluctance machine include the effect of rotor iron saturation. Characteristic curves depicting nondimensional expressions developed for the rotor impedance factor and the power factor enable a visualization of the effects of 1) ratio of depth of saliency to depth of penetration, 2) slit number and depth, and 3) effective resistivities and saturation flux densities of different regions of the rotor on rotor parameter variations. Further predicted values are compared with experimental values and conclusions are drawn. 相似文献
965.
966.
L. Barbareschi C. La Padula M. Mastropietro F. Perotti G. Villa A. Bazzano L. Boccaccini R. Patriarca V.F. Polcaro P. Ubertini R.C. Butler G. Di Cocco G. Spada J.N. Carter P. Charalambous A.J. Dean J.B. Stephen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(4):91-93
In order to improve the low energy capability (15 ÷ 150 KeV) of the balloon borne “ZEBRA” low energy gamma imaging telescope (150 KeV-20 MeV), a large area, high spectral resolution (5% at 60 KeV), low background detector has been designed and is now under development.It consists of two MultiWire Spectroscopic Proportional Counter (SPC), escape gated, that have a sensitive area of 6000 cm2, and are placed above the large area array of sodiumiodide position sensitive elements. 相似文献
967.
L.E. Link W.B. Krabill R.N. Swift 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(2):309-322
Airborne laser systems have demonstrated enormous potential for topographic and bathymetric mapping. Both profiling and scanning systems have been evaluated for terrain elevation mapping, stream valley cross-section determination, and nearshore bottom profiling. Performance of the laser systems has been impressive and for some applications matches current operational accuracy requirements. Determining the position of individual laser measurements remains a constraint for most applications. Laser technology constrains some terrain and bathymetric applications, particularly for water penetration and frequency of measurements for high-spatial resolution over large areas. 相似文献
968.
D.L. DeVincenzi P.D. Stabekis J.B. Barengoltz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(8):13-21
In order to control contamination of planets by terrestrial microorganisms and organic constituents, U.S. planetary missions have been governed by a planetary protection (or planetary quarantine) policy which has changed little since 1972. This policy has recently been reviewed in light of new information obtained by planetary exploration during the past decade and because of changes to, or uncertainties in, some parameters used in the existing quantitative approach. On the basis of this analysis, a new planetary protection policy, with the following key features, is proposed: deemphasizing the use of mathematical models and quantitative analyses; establishing requirements for target planet/mission type (i.e., orbiter, lander, etc.) combinations; considering sample return missions a separate category; simplifying documentation; and imposing implementing procedures (i.e., trajectory biasing, cleanroom assembly, spacecraft sterilization, etc.) by exception, i.e., only if the planet/mission combination warrants such controls. Interpretation of the new policy for missions like Galileo, Mars Surface Sample Return, Saturn Orbiter with Twin Probes, and missions to comets are considered. In general, the new policy proposes elimination of all but documentation requirements for most planetary missions and simplification of the remaining compliance procedures. 相似文献
969.
D S Bergtold A B Cox C M Su J T Lett 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(8):221-229
Skin biopsies were taken from the central regions of the ears of New Zealand white rabbits following localized exposure of one ear of each rabbit to 530 MeV/amu Ar or 365 MeV/amu Ne ions. The unirradiated ears served as controls. Biopsies were taken also from the chests and inner thighs of rhesus monkeys after whole-body exposure to 32 MeV protons and from unirradiated control animals. The linear energy transfers (LET infinity's) for the radiations were 90 +/- 5, 35 +/- 3, and approximately 1.2 keV/micrometer, respectively. In the rabbit studies, explants were removed with a 2 mm diameter dermal punch at post-irradiation times up to five years after exposure. Similar volumes of monkey tissue were taken from skin samples excised surgically 16-18 years following proton irradiation. Fibroblast cultures were initiated from the explants and were propagated in vitro until terminal senescence (cessation of cell division) occurred. Cultures from irradiated tissue exhibited decreases in doubling potential that were dependent on radiation dose and LET infinity and seemed to reflect damage to stem cell populations. The implications of these results for astronauts exposed to heavy ions and/or protons in space include possible manifestations of residual effects in the skin many years after exposure (e.g. unsatisfactory responses to trauma or surgery). 相似文献
970.