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981.
982.
Recent developments in the physics input for iron core collapse models of type II supernovae are reviewed. The effect of these developments on collapse calculations is also discussed. The inner core collapses homologously, with little change in specific entropy, bounces in the neighborhood of nuclear density, and sets up an outward moving shock. In adiabatic models an explosion may result. The Inclusion of neutrino effects may produce substantial shock damping. Current results indicate that core collapse, bounce and shock propagation does not produce an explosion when neutrino effects are included. 相似文献
983.
The defruiter that is employed in the Air Traffic Control Radar Beacon System (ATCRBS) to prefilter asynchronous replies has a complex impact on the detection, estimation and validation properties of the detection subsystem. Its positive and negative effects are quantitatively enumerated via a simulation of the beacon processing subsystem of the Automated Radar Terminal System (ARTS III). It is concluded that the disadvantages of using the present-day defruiter in the ARTS III digital processing channel outweigh the advantages when fruit rates are below several thousand per scan. As an alternative to the total elimination of the defruiter a more general class of preprocessors is defined and their input-output relationships are derived using a Markov Chain formulation. These are found to represent an improvement over the current defruiter in that the positive effects of defruiting are retained while some of the negative effects are reduced. 相似文献
984.
Accurate solutions of minimal time Earth-Mars and Earth-Venus heliocentric trajectories are calculated with a shooting-Newton method. The flight times are less and the steering histories are diferent than those presented in [1], thus contradicting the optimality claims in [1]. 相似文献
985.
The resolution and tracking of radar targets which are close to. gether is a classical problem which is receiving increased attention. Improving the angular resolution by sampling the received wave front along the aperture and then applying modern "high resolution" spectrum estimation techniques (e. g., maximum likelihood and maximum entropy processing) to the spatial sample data is discussed. Experimental results are presented for the application ion of these techniques to field data from a L- band line array. 相似文献
986.
R.B. Stoltzfus S.A. Bowhill L.G. Smith 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(6):143-146
The Langmuir-probe technique for measurement of electron concentration in the mesosphere is capable of excellent altitude resolution, of order 1 m. Measurements from nine rocket flights frequently show small-scale ionization structures in the altitude region 60–90 km. These are believed to be identical with regions of strong coherent backscatter seem by VHF radars at Jicamarca, Peru and Urbana, Illinois. They are believed to represent intermittent turbulence attributable to nonlinear interaction of waves in the mesosphere. Parameters of the turbulent regions are estimated. 相似文献
987.
lt is possible that usable combination codes can be obtained if Barker and Huffman sequences are chosen as the inner and outer codes. lt is shown that an improvement in either energy efficiency or time sidelobe structure will result either from a modification of a Huffman sequence or from a modification of a Barker sequence. Results are given for a combination code of length 91, with inner and outer codes of length 7 and 13. 相似文献
988.
Charles F. Lillie Charles W. Hord Kevin Pang David L. Coffeen James E. Hansen 《Space Science Reviews》1977,21(2):159-181
The Voyager Photopolarimeter Experiment is designed to determine the physical properties of particulate matter in the atmospheres of Jupiter, Saturn, and the Rings of Saturn by measuring the intensity and linear polarization of scattered sunlight at eight wavelengths in the 2350–7500 Å region of the spectrum. The experiment will also provide information on the texture and probable composition of the surfaces of the satellites of Jupiter and Saturn and the properties of the sodium cloud around Io. During the planetary encounters a search for optical evidence of electrical discharges (lightning) and auroral activity will also be conducted. 相似文献
989.
Frederick L. Scarf 《Space Science Reviews》1974,15(6):933-950
A study has been carried out to identify the controlled space physics and plasma physics experiments that can be performed from the space shuttle on sortie missions of 7 to 30-day duration. An experiment facility of this type appears to be well-matched to the sortie missions capability, and a technically feasible laboratory can provide a base for an extensive and significant research program to be carried out during the 1980–1990 time period. The laboratory, known as PPEPL, consists of a 33-ft pallet of instruments connected to a 25-ft pressurized control module. Two deployable 50-m booms, two subsatellites, a high power transmitter, a multipurpose high-power accelerator array, a set of deployable canisters for releases, and a gimbaled platform for pointing instruments are the primary systems mounted on the pallet. 相似文献
990.
Cole S.N. Sjoberg E.S. Fanuele M.A. Rittenbach O.E. Olesch R.G. 《IEEE transactions on aerospace and electronic systems》1979,(5):594-599
The environment and radar operation simulator (EROS) is a hardware system whose function is to produce realistic synthetic radar backscatter, incorporating both target and clutter. The simulator is electrically connected to a subject radar and responds in real time to the radar's antenna scan angle by producing the correct composite video signal. 相似文献