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921.
Hassanali Akbari Asti Bhatt Cesar La Hoz Joshua L. Semeter 《Space Science Reviews》2017,212(1-2):249-294
Space plasmas are host to the electrostatic Langmuir waves and a rich range of processes associated with them. Many of such processes that are of interest in micro-scale plasma physics and magnetosphere-ionosphere physics are open to investigation via incoherent scatter plasma lines—i.e., a pair of resonant peaks in the incoherent scatter radar (ISR) spectrum, symmetrically displaced from the radar transmitting frequency by about the plasma frequency, as the signature of Langmuir waves in the ISR spectrum. There now exists a large body of literature devoted to the investigation of a number of topics in ionospheric physics via plasma line theory and observation. It is the goal of this work to provide a comprehensive review of this literature, from the early theoretical works on oscillations in magnetized plasma to the recent advances in plasma line measurements and applications. This review includes detailed theoretical discussions on the intensity and frequency displacement of plasma lines. It reviews the experimental observations of plasma lines enhanced by various sources of energy and discusses the implications of the observations in the context of ionospheric physics. The review also covers the practical aspects of plasma line measurements, from measurement techniques to the applications of plasma lines in estimating the bulk parameters of the ionosphere. 相似文献
922.
S. A. Mikhailov L. V. Korotkov S. A. Alimov D. V. Nedel’ko 《Russian Aeronautics (Iz VUZ)》2011,54(3):247-253
A technique is suggested for calculating the helicopter spatial motion and the stress-strain state of a skid landing gear
in the course of landing with regard for the second landing impact; geometric, material and design nonlinearity of undercarriage
springs deformation is taken into account. The comparison between the analysis results and experimental data is presented. 相似文献
923.
W.D. Apel J.C. Arteaga L. Bähren K. Bekk M. Bertaina P.L. Biermann J. Blümer H. Bozdog I.M. Brancus P. Buchholz S. Buitink E. Cantoni A. Chiavassa K. Daumiller V. de Souza F. Di Pierro P. Doll M. Ender R. Engel H. Falcke M. Finger D. Fuhrmann H. Gemmeke C. Grupen A. Haungs D. Heck J.R. Hörandel A. Horneffer D. Huber T. Huege P.G. Isar K.-H. Kampert D. Kang O. Krömer J. Kuijpers K. Link P. Łuczak M. Ludwig H.J. Mathes M. Melissas C. Morello S. Nehls J. Oehlschläger N. Palmieri T. Pierog J. Rautenberg H. Rebel M. Roth C. Rühle A. Saftoiu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
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926.
Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments 总被引:1,自引:0,他引:1
Paul B. Niles David C. Catling Gilles Berger Eric Chassefière Bethany L. Ehlmann Joseph R. Michalski Richard Morris Steven W. Ruff Brad Sutter 《Space Science Reviews》2013,174(1-4):301-328
Ongoing research on martian meteorites and a new set of observations of carbonate minerals provided by an unprecedented series of robotic missions to Mars in the past 15 years help define new constraints on the history of martian climate with important crosscutting themes including: the CO2 budget of Mars, the role of Mg-, Fe-rich fluids on Mars, and the interplay between carbonate formation and acidity. Carbonate minerals have now been identified in a wide range of localities on Mars as well as in several martian meteorites. The martian meteorites contain carbonates in low abundances (<1 vol.%) and with a wide range of chemistries. Carbonates have also been identified by remote sensing instruments on orbiting spacecraft in several surface locations as well as in low concentrations (2–5 wt.%) in the martian dust. The Spirit rover also identified an outcrop with 16 to 34 wt.% carbonate material in the Columbia Hills of Gusev Crater that strongly resembled the composition of carbonate found in martian meteorite ALH 84001. Finally, the Phoenix lander identified concentrations of 3–6 wt.% carbonate in the soils of the northern plains. The carbonates discovered to date do not clearly indicate the past presence of a dense Noachian atmosphere, but instead suggest localized hydrothermal aqueous environments with limited water availability that existed primarily in the early to mid-Noachian followed by low levels of carbonate formation from thin films of transient water from the late Noachian to the present. The prevalence of carbonate along with evidence for active carbonate precipitation suggests that a global acidic chemistry is unlikely and a more complex relationship between acidity and carbonate formation is present. 相似文献
927.
Test requirements, which are generally collected in multiple disparate formats throughout the life cycle of an electronic product, could be used in various applications that reduce test and development cycle times and increase the confidence in the final test program. Unfortunately, test requirements are seldom captured in a consistent format that may be processed by a computer, thus eliminating the possibility of using such requirements in an engineering application. Additionally, such an approach disallows test requirements captured in one segment of the product life cycle to be reused in subsequent life cycle stages. This paper describes a model-based methodology, specifically the Test Requirements Model (TeRM), which can be shown to facilitate the transfer of test-related product information between various stages of the life cycle. This transportability, in conjunction with an exchange format that can be processed by a computer, permits test requirement information to support value-added applications in the engineering process throughout the life cycle of a product 相似文献
928.
Performance of 10- and 20-target MSE classifiers 总被引:2,自引:0,他引:2
Novak L.M. Owirka G.J. Brower W.S. 《IEEE transactions on aerospace and electronic systems》2000,36(4):1279-1289
MIT Lincoln Laboratory is responsible for developing the ATR (automatic target recognition) system for the DARPA-sponsored SAIP program; the baseline ATR system recognizes 10 GOB (ground order of battle) targets; the enhanced version of SAIP requires the ATR system to recognize 20 GOB targets. This paper presents ATR performance results for 10- and 20-target mean square error (MSE) classifiers using high-resolution SAR (synthetic aperture radar) imagery. 相似文献
930.