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881.
Benchmark for radar allocation and tracking in ECM 总被引:4,自引:0,他引:4
882.
Estimates of drag characteristics of the space vehicles with orbit heights of 450–540 and 700–900 km before and after strong
(with a magnitude M ≥ 6.5) crust earthquakes of 2000–2006 are presented. The method of estimation of seismic orbital effects is presented using
as an example the small Mozhaets-4 spacecraft. Two weeks prior to earthquakes, variations in the drag of low-orbital spacecraft increase. 3–6 days prior to
strong crust earthquakes with epicenters on the land, the drag of low-orbit spacecraft in the upper atmosphere increases.
The effect of increased viscosity of the neutral component of the atmosphere at spacecraft heights 3–6 days prior to strong
crust earthquakes is consistent with the results of studies of disturbances in the ionization density variations in the ionospheric
F region prior to earthquakes. No anomalies are found in the day of the earthquake. In the future, it is proposed to use elements
of space debris for diagnostics of seismic orbital effects and disturbances of the upper atmosphere. 相似文献
883.
E.G. Berezhko 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(3):429-441
We analyse the results of recent measurements of nonthermal emission from individual supernova remnants (SNRs) and their correspondence to the nonlinear kinetic theory of cosmic ray (CR) acceleration in SNRs. It is shown that the theory fits these data in a satisfactory way and provides the strong evidences for the efficient CR production in SNRs accompanied by significant magnetic field amplification. Magnetic field amplification leads to considerable increase of CR maximum energy so that the spectrum of CRs accelerated in SNRs is consistent with the requirements for the formation of Galactic CR spectrum up to the energy ∼1017 eV. 相似文献
884.
M.B. Moldwin D. Fiello E. Harter G. Holman N. Nagumo A. Pryharski C. Takunaga 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
An elementary science education professional development partnership between Culver City Unified School District teachers and UCLA has been formed. The project was designed to assist teachers to comfortably present introductory space science concepts, to support them in their efforts, and to aid them in encouraging their students to develop inquiry skills related to space sciences. The project encourages teacher use of observational science techniques in their classrooms, the use of NASA solar mission images and enhanced use of astronomical observation to facilitate discovery learning. The integrated approach of the project has fostered collegial learning activities among the participating teachers and offered them opportunities for continued renewal and professional development of teacher competencies in astronomy and space science. The activities used in the classroom were developed by others, classroom tested, and specifically address National Science Education and California Science Content Standards. These activities have been sustained through on-going collaboration between the scientist and the teachers, a summer Research Experience for Teachers program, and on-going, grade-specific, district-sponsored workshops. Assessment of the value of the program is done by the school district and is used to continuously improve each workshop and program component. Culver City (California) Unified School District is a small urban school district located on the Westside of Los Angeles. This paper describes the program and the plans for incorporating IHY-themed science into the classroom. 相似文献
885.
Yihua Zheng Anthony T.Y. Lui Mei-Ching Fok Brian J. Anderson Pontus C. Brandt Donald G. Mitchell 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(8):1234-1242
One essential component of magnetosphere and ionosphere coupling is the closure of the ring current through Region 2 field-aligned current (FAC). Using the Comprehensive Ring Current Model (CRCM), which includes magnetosphere and ionosphere coupling by solving the kinetic equation of ring current particles and the closure of the electric currents between the two regions, we have investigated the effects of high latitude potential, ionospheric conductivity, plasma sheet density and different magnetic field models on the development of Region 2 field-aligned currents, and the relationship between R2 FACs and the ring current. It is shown that an increase in high latitude potential, ionospheric conductivity or plasma sheet density generally results in an increase in Region 2 FACs’ intensity, but R2 FACs display different local time and latitudinal distributions for changes in each parameter due to the different mechanisms involved. Our simulation results show that the magnetic field configuration of the inner magnetosphere is also an important factor in the development of Region 2 field-aligned current. More numerical experiments and observational results are needed in further our understanding of the complex relationship of the two current systems. 相似文献
886.
Stephen W. Bougher Pierre-Louis Blelly Michael Combi Jane L. Fox Ingo Mueller-Wodarg Aaron Ridley Raymond G. Roble 《Space Science Reviews》2008,139(1-4):107-141
Numerical modeling tools can be used for a number of reasons yielding many benefits in their application to planetary upper atmosphere and ionosphere environments. These tools are commonly used to predict upper atmosphere and ionosphere characteristics and to interpret measurements once they are obtained. Additional applications of these tools include conducting diagnostic balance studies, converting raw measurements into useful physical parameters, and comparing features and processes of different planetary atmospheres. This chapter focuses upon various classes of upper atmosphere and ionosphere numerical modeling tools, the equations solved and key assumptions made, specified inputs and tunable parameters, their common applications, and finally their notable strengths and weaknesses. Examples of these model classes and their specific applications to individual planetary environments will be described. 相似文献
887.
Algorithms for determining fixed-pitch propeller parameters and some flight characteristics of a superlight aircraft at the early stage of designing are described. 相似文献
888.
Carpi F. Tralli A. Rossi D.D. Gaudenzi P. 《IEEE transactions on aerospace and electronic systems》2007,43(1):79-92
This paper presents results of a preliminary study of feasibility for the application of electroactive polymer (EAP) based actuators to a robotic locomotion system, intended by the European Space Agency (ESA) to operate on the surface of Mars. The system is conceived as an elastic spherical rover, exploiting wind propulsion for surface motion, while adopting an active mechanism for vertical jumping over obstacles. The use of polymeric electromechanical devices is envisaged in order to provide actuation to such a jumping mechanism. Among the available EAP technologies, new contractile linear actuators based on dielectric elastomers arc proposed in this study as suitable devices and two potential solutions concerning their use are designed, modeled, and evaluated via numerical simulations. The best solution reveals interesting simulated performances, enabling jumping of obstacle heights corresponding to more than 7% of the diameter of the rover 相似文献
889.
Richard G. Lugar 《Space Policy》1985,1(3):231-236
Senator Lugar argues that a better European appreciation of the SDI is essential to try to define the roles of the US allies in the programme. A number of guidelines for allied participation should be applied, covering mode of participation, areas for participation, responsibilities under treaty provisions, technology transfer and security safeguards. Bilateral agreements are viewed as the mode for proceeding, but it is incumbent on the US government to outline the next steps it evisages to come to grips with the political considerations that will influence allied calculations on whether and under what circumstances to participate in SDI research. 相似文献
890.
J. Heise J.A.M. Bleeker A.C. Brinkman E. Gronenschild F. Paerels M. Grewing C. Wulf-Mathies K. Beuerman 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(3):61-64
EXOSAT has observed 19 hot white dwarfs with alleged strong soft X-ray emission. Positive detection of a large fraction of this sample was obtained, among these practically all hot DA dwarfs. High-resolution spectral data, acquired with the 500 1/mm grating spectrometer, indicates no traces of He in the atmosphere of HZ43, i.e. n(He)/n(H) ? 10?5 at a photospheric temperature of 60000 K (log g = 8). In contrast, the hot DA1 dwarf Feige 24 shows the presence of an appreciable He-abundance (n(He)/n(H) ? 10?3); however no simple homogeneously mixed H/He atmosphere can explain the observed spectral shape. 相似文献