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991.
Software Techniques for Detecting False SSR Tracks 总被引:1,自引:0,他引:1
The problem of detecting false secondary surveillance radar (SSR) tracks due to electromagnetic reflections is discussed. An approach via software is considered and some algorithms for the SSR tracks detection are proposed. Some experimental results are reported. 相似文献
992.
In a dense detection environment track-while-scan algorithms will introduce many false tracks when processing is performed on a scan-by-scan basis. The maximum likelihood solution involving all detections on all scans is formulated and evaluated for the initiation problem consisting of false alarms, missed detections, and unresolved detections. A comparison is made between the maximum likelihood solutions including and not including the resolution likelihood and it is shown that the resolution likelihood must be included if the data contain unresolved detections. While the maximum likelihood method (with unresolved detections) does not appear to be implementable in real time without very high speed integrated circuit (VHSIC) technology, it can be used as a standard to which more implementable methods can be compared. 相似文献
993.
994.
Curves are presented showing the additional constant false-alarm rate (CFAR) loss which results when a "greatest of" logic is imple mented between the leading and lagging sets of reference cells. Thee analytical results for a square law detector and a Swerling case 1 fluctuating target are supplemented by simulation results for a nonfluctuating target, and envelope and logarithmic detector laws. 相似文献
995.
V. A. Yaroshevskii 《Cosmic Research》2001,39(1):38-45
Using the method of averaging, the condition is derived of the regime of plane autorotation for an axisymmetric spacecraft at its initial stage of reentry into the atmosphere, where one can assume the velocity head to be an exponential function of time. The results obtained by this method are compared with the results of numerical calculations. Special attention is given to the regimes of long spacecraft hovering in the vicinity of an unstable equilibrium position. Analytical estimates are made for these regimes. 相似文献
996.
Telemedicine has the potential to have a greater impact on the future of medicine than any other modality and will profoundly alter the medical landscape of the twenty-first century. In the most remote areas, it can bring high-quality health care where none is now available. In global health care, it can enhance and standardize the quality of medical care, including developing countries. In the realm of space flight, it can provide a lifeline to medical expertise and monitoring. Through its mobility, it can provide urgently needed health care in instances of natural disaster. However, a number of challenges exist in its coordination and implementation on a global scale, specifically in the international and remote disaster scenarios. In the area of spaceflight, telemedicine capability will remain a consultation/information ‘lifeline’, but additional onboard medical capability and expertise will become crucial complements as missions become more advanced and remote from Earth. 相似文献
997.
L A Somova N S Pechurkin V I Polonsky T I Pisman A B Sarangova M Andre G M Sadovskaya 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(10):1939-1943
The effect has been studied of inoculation of seeds of wheat with two species of rhizospheric microorganisms--Pseudomonas fluorescens and Pseudomonas putida--on young plant growth with complete and with nitrogen deficit mineral nutrition. With complete mineral medium, plants grown from seeds inoculated with bacteria of Pseudomonas genus (experiment plants) have been found to have better growth over plants not inoculated with these bacteria (control plants). The experiment plants had increased transpiration and their biomass had higher organic nitrogen content. With nitrogen deficit medium, the plants inoculated with bacteria and those without them, have not revealed changes in growth. Neither case demonstrated competition of microorganisms with plants for nitrogen sources. 相似文献
998.
I. Apáthy I. Szemerey P. Bencze K. Kovács V. Afonin V. Bezrukih K. Gringauz N. Shutte 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(12):101-105
Ion temperature and total ion concentration measured on 25th October 1977 during the flight of the geophysical rocket “Vertical-6” are analyzed. The solar EUV fluxes determined in five wave-length bands with a photoelectron analyzer are also given. The observed anomalous variation of ion temperature between 700 and 900 km and the measured ion concentration can be explained, if the charge exchange reactions H+ ? O+ and diffusion are taken into account. 相似文献
999.
In a phased array antenna, the phase shifters (or T/R modules in an active aperture phased array) with their beam-steering control circuitry along with the feed network account for the major hardware cost. This paper presents two antenna array configurations that use simpler feed, simpler phase-shifting and simpler beam-steering control circuitry for realizing low-cost phased arrays. Both are lens configurations. The first one uses a Radant lens, which provides a medium that is loaded with diodes and provides the needed phase shift by switching the diodes on and off. The other configuration employs a ferroelectric dielectric material whose dielectric constant can be varied with an applied DC bias voltage. It is shown that the ferroelectric lens may have further advantages of smaller thickness, simpler beam-steering controls and lower cost 相似文献
1000.
V.L. Barsukov C.P. Florensky 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(8):41-47
On the base of the comparative planetologic study of the Moon and terrestrial planets two fundamental features of their history and structure have been established.Firstly, shell-like structure of the terrestrial planets could be understood only in the terms of the heterogeneous accretion theory. At the final stages of major terrestrial planet formation the leading role belonged to the planetosimals of carbonaceous chondritic composition. Secondly, there are two types of the crust on the planetary surface. Their formation are considered to be independent and differing in the geological time. The primary planetary crust of predominantly feldspathic composition is considered to form during the pregeologic period at the final stage of planetary formation due to the impact-explosive processes. The hydrosphere and atmosphere is thought to appear contemporaneously. The basaltic planetary crust is forming later due to the radioactive decay and superimposed on the primary feldspathic crust. 相似文献