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101.
F. Capitanio A. Bazzano P. Ubertini G. De Cesare M. Del Santo A. Tarana A. Joinet 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2816-2819
On March 2003, IBIS, the γ-ray imager on board the INTEGRAL satellite, detected an outburst from a new source, IGR J17464-3213, that turned out to be an HEAO-1 transient, namely H1743-322. The spectral and temporal evolutions of the source were observed by INTEGRAL in different periods. Also RXTE observed the source for the first time on 2003 March 29 during a PCA Galactic bulge scan. The source flux decayed below the RXTE PCA sensitivity limit in November 2003, then in April 2004 it was again detected by INTEGRAL. On July 3, 2004 the source was again detected by RXTE/PCA at a 2–10 keV intensity of 16 mCrab and on July 7, reached 69 mCrab. Recently, a new outburst was observed on August 2005. We briefly summarise here the behaviour of the source observed by INTEGRAL from March 2003 to August 2005. The new outbursts of the source and the analysis of all the data collected (now public) give a global view of the spectral and time behaviour of this X-ray transient. 相似文献
102.
Kacelenga R. Erickson D. Palmer D. 《Aerospace and Electronic Systems Magazine, IEEE》2003,18(8):13-19
This paper presents a voting fusion application for use with a remotely controlled multisensor vehicle platform for antitank landmine detection. Data from three landmine detection sensors mounted at the front of the vehicle enhance the probability of detection and, when combined via data fusion, limit the false alarm density to practical levels. The performance of the voting fusion scheme presented in this paper is contrasted with a heuristic data fusion approach developed by General Dynamics Canada. 相似文献
103.
C Lindberg G Horneck 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(3):277-280
The ESA MarsNet mission proposal consists most probably of a trio of Mars landers. These landers each contain a variety of scientific equipment. The network of stations demands for a definition of its planetary protection requirements. With respect to the MarsNet mission only forward contamination problems will be considered. Future involvement of European efforts in planetary exploration including sample returns will also raise the problem of back contamination. A tradeoff study for the overall scientific benefit with respect to the approximative cost is necessary. Planetary protection guide-lines will be proposed by an interdisciplinary and international board of experts working in the fields of both biology and planetary science. These guide-lines will have to be flexible in order to be modified with respect to new research results, e.g. on adaptation of microorganisms to extreme (space) conditions. Experiments on the survival of microorganisms at conditions of simulated Mars surface and subsurface will have to be conducted in order to obtain a baseline data collection as a reference standard for future guide-lines. 相似文献
104.
Robert J. HaydukWalter S. ScottGerald D. WalbergJames J. ButtsRichard D. Starr 《Acta Astronautica》1996,39(9-12):677-686
The Small Satellite Technology Initiative (SSTI) is a National Aeronautics and Space Administration (NASA) program to demonstrate smaller, high technology satellites constructed rapidly and less expensively. Under SSTI, NASA funded the development of “Clark,” a high technology demonstration satellite to provide 3-m resolution panchromatic and 15-m resolution multispectral images, as well as collect atmospheric constituent and cosmic x-ray data. The 690-Ib. satellite, to be launched in early 1997, will be in a 476 km, circular, sun-synchronous polar orbit. This paper describes the program objectives, the technical characteristics of the sensors and satellite, image processing, archiving and distribution. Data archiving and distribution will be performed by NASA Stennis Space Center and by the EROS Data Center, Sioux Falls, South Dakota, USA. 相似文献
105.
Pulse chasing is a technique implemented by a bistatic or multistatic radar system that allows rapid and efficient search of a desired volume of space whereby the receiving antenna is made to follow or “chase” the transmitted pulse as it travels radially outward from the transmitter antenna. An expression for receiver antenna scan rate requirements is derived that corrects an error in the prior literature. The results give significantly reduced scan rates in the forward scatter region near the baseline showing that pulse chasing is more easily implemented using conventional analog beamformer phased array technology than was suggested by prior work 相似文献
106.
Hwu S.U. Loh Y.C. Dobbins J.A. Kroll Q.D. Sham C.C. 《Aerospace and Electronic Systems Magazine, IEEE》2005,20(10):9-14
Computational investigations and experimental measurements were performed to evaluate the Space Shuttle UHF communication system performance for payload bay antenna at the proposed new location. To insure adequate communication coverage at relocated new location, the link margin for the Extravehicular Activity (EVA) astronauts and between Space Shuttle Orbiter and International Space Station (SSO-ISS) during rendezvous were analyzed. The multipath effects from the vehicle structures surrounding the antenna were investigated. The Radio Frequency (RF) electromagnetic radiation to the Orbiter Docking System (ODS) pyrotechnics was also analyzed to ensure the EMC/EMI compliances. 相似文献
107.
Closed-form expressions are derived for the output noise response of an ?-?-? filter in steady-state operation with constant measurement noise statistics. To the author's knowledge such expressions have been unavailable until now. These formulas are useful for target tracking applications. 相似文献
108.
109.
110.
D.I. Kosenko S.I. Blinnikov K.A. Postnov P. Lundqvist E.I. Sorokina 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(12):2705-2710
Time-dependent thermal X-ray spectra are calculated from physically plausible conditions around GRB. It is shown that account for time-dependent ionization processes strongly affects the observed spectra of hot rarefied plasma. These calculations may provide an alternative explanation to the observed X-ray lines of early GRBs afterglows (such as GRB 011211). Our technique will allow one to obtain independent constraints on the GRB collimation angle and on the clumpiness of circumstellar matter. 相似文献