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611.
The space-based Solar and Heliospheric Observatory (SOHO) is a joint venture of ESA and NASA within the frame of the Solar Terrestrial Science Programme (STSP), the first Cornerstone of ESA's long-term programme Space Science — Horizon 2000. The principal scientific objectives of the SOHO mission are: a) a better understanding of the structure and dynamics of the solar interior using techniques of helioseismology, and b) a better insight into the physical processes that form and heat the Sun's corona, maintain it and give rise to its acceleration into the solar wind. To achieve these goals, SOHO carries a payload consisting of 12 sets of complementary instruments which are briefly described here. 相似文献
612.
I Podolsky A Mashinsky 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(11):39-46
Aboard the orbital stations, "Salyut-7" and "Mir", investigations on the peculiarities of moisture transfer in capillary-porous bodies (CPB; that is, soil substitutes) in microgravity were conducted by the authors with a specially designed device and an original method. Water distribution in CPB-perlite (fractions 1.5... 2.5 mm) was studied, and theoretical dependances for linear capillary impregnation of CPB were determined. 相似文献
613.
Vadher V.V. Smith I.R. Williams S. 《IEEE transactions on aerospace and electronic systems》1986,(5):573-582
DC-link converters having a variable input frequency but a constant output frequency now provide a viable alternative to the constant-speed mechanical drive as a means of providing a constant frequency power supply from an aircraft generator. The ease of replacement and repair, the reduction in servicing needs, and the ability to locate the components of the electrical system throughout the aircraft all combine to bring about a considerable reduction in the maintenance time which is required. A computationally efficient technique for the mathematical modeling of a typical electrical system, in which the overall power network is torn initially into a set of convenient subnetworks, is described. Connection matrices are employed to combine the equations computed for the various subnetworks with the equations for the overall network. Typical results are presented for the overall system. The performance detail enables many important design considerations to be investigated prior to manufacture. 相似文献
614.
M.I. Pudovkin S.A. Zaitseva B.P. Besser 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(12):1909-1912
The earthward displacement of the magnetopause observed during a southward IMF (or the magnetopause erosion) and its dependence on the solar wind plasma and magnetic field parameters is studied by investigating data of about 30 magnetopause crossings by the ISEE 1 and 2 spacecraft. It is shown that the magnetopause erosion may be explained by a depression of the magnetic field intensity in the dayside magnetosphere caused by the penetration of the magnetosheath magnetic field (component perpendicular to the reconnection line) into the magnetosphere. The penetration coefficient (the ratio of the intensity of the penetrated field to the intensity of the magnetosheath magnetic field) is estimated and found to equal approximately 1. 相似文献
615.
Yu.A. Akatov T.V. Batenchuk A.M. Borodin V.E. Dudkin A.M. Marenny V.A. Sakovich G.G. Vasilev A.G. Karadjov P.P. Szab I. Fehr W. Malz G. Voigtman D. Hasheganu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(14):67-71
During the 3rd main expedition on board the “Salyut-6” orbital station in 1979 the integral characteristics of cosmic radiation were measured in various positions inside the manned modules (experiment “Integral”). Measurements were performed with thermoluminescent dosimeters, photographic films and solid state plastic detectors supplied for the experiment by specialists of the USSR, Bulgaria, Hungary, GDR and Romania. The dose gradient inside the manned modules of the station amounted to 70 % for long intervals of time. During the experimental period the dose rate inside the station was 15 to 30 mrad per day. The mean flux of particles with z 6 and LET 200 keV/μm was found to be 0.22 cm−2 day−1. 相似文献
616.
R. Hudec Z. Ceplecha J. Ehrlich J. Borovi
ka K. Hurley J.-L. Ateia C. Barat M. Niel G. Vedrenne I.V. Estulin A.K. Kuznetsov V.M. Zenchenko T.L. Cline U. Desai W.D. Evans E. Fenimore R. Klebesadel J. Laros 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
The preliminary results from optical search for light pulses associated with gamma ray bursts by means of the Czechoslovak Fireball Network plate collection at the Ondřejov observatory are given. Optical monitoring represents more than 7700 hours, but no real optical counterpart was found. Problems associated with the optical search for gamma ray bursts are discussed. 相似文献
617.
D.N. Baker T.I. Pulkkinen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(12):1923-1927
Methods are discussed to estimate energy transfer from the solar wind to the magnetosphere during substorm growth phases. Observational and modeling constraints are then used to assess quantitatively the total amount of energy stored in the magnetotail. The major avenues of energy dissipation are examined and the energy that is released in the form of plasma sheet heating, ionospheric Joule heating, plasmoids, and energetic particle production during substorms is assessed. Energy sources are evaluated to drive substorm evolution in a particularly well-observed case: stored tail-lobe energy is sufficient to drive observed substorm dissipation processes (by large margins). On the other hand, energy in the closed field lines of the plasma sheet is insufficient to supply the substorm energy. Hence, magnetic reconnection is required on energy grounds during well-observed substorm cases. 相似文献
618.
High accuracy satellite drag model (HASDM) 总被引:2,自引:0,他引:2
Mark F. Storz Bruce R. Bowman Major James I. Branson Stephen J. Casali W. Kent Tobiska 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,36(12):2497-2505
The dominant error source in force models used to predict low-perigee satellite trajectories is atmospheric drag. Errors in operational thermospheric density models cause significant errors in predicted satellite positions, since these models do not account for dynamic changes in atmospheric drag for orbit predictions. The Air Force Space Battlelab’s High Accuracy Satellite Drag Model (HASDM) estimates and predicts (out three days) a dynamically varying global density field. HASDM includes the Dynamic Calibration Atmosphere (DCA) algorithm that solves for the phases and amplitudes of the diurnal and semidiurnal variations of thermospheric density near real-time from the observed drag effects on a set of Low Earth Orbit (LEO) calibration satellites. The density correction is expressed as a function of latitude, local solar time and altitude. In HASDM, a time series prediction filter relates the extreme ultraviolet (EUV) energy index E10.7 and the geomagnetic storm index ap, to the DCA density correction parameters. The E10.7 index is generated by the SOLAR2000 model, the first full spectrum model of solar irradiance. The estimated and predicted density fields will be used operationally to significantly improve the accuracy of predicted trajectories for all low-perigee satellites. 相似文献
619.
Advanced architectures for real-time Delay-Doppler Map GNSS-reflectometers: The GPS reflectometer instrument for PAU (griPAU) 总被引:1,自引:0,他引:1
E. Valencia A. CampsJ.F. Marchan-Hernandez X. Bosch-LluisN. Rodriguez-Alvarez I. Ramos-Perez 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
In recent years Global Navigation Satellite System’s signals Reflectometry (GNSS-R) has stood as a potential powerful remote sensing technique to derive scientifically relevant geophysical parameters such as ocean altimetry, sea state or soil moisture. This has brought out the need of designing and implementing appropriate receivers in order to track and process this kind of signals in real-time to avoid the storage of huge volumes of raw data. This paper presents the architecture and performance of the Global Positioning System (GPS) Reflectometer Instrument for PAU (griPAU), a real-time high resolution Delay-Doppler Map reflectometer, operating at the GPS L1 frequency with the C/A codes. The griPAU instrument computes 24 × 32 complex points DDMs with configurable resolution (ΔfDmin = 20 Hz, Δτmin = 0.05 chips) and selectable coherent (minimum = 1 ms, maximum = 100 ms for correlation loss Δρ < 90%) and incoherent integration times (minimum of one coherent integration period and maximum not limited but typically <1 s). A high sensitivity (DDM peak relative error = 0.9% and DDM volume relative error = 0.03% @ Ti = 1 s) and stability (Δρ/Δt = −1 s−1) have been achieved by means of advanced digital design techniques. 相似文献
620.
E.?I.?ZhukovaEmail author Kh.?V.?Malova V.?Yu.?Popov E.?E.?Grigorenko A.?A.?Petrukovich L.?M.?Zelenyi 《Cosmic Research》2017,55(6):417-425
This work is devoted to studying the processes of the acceleration of plasma particles in thin current sheets that appear during magnetospheric substorms in the Earth’s magnetosphere tail. A numerical model of magnetic dipolarization accompanied by plasma turbulence has been constructed and studied. The model allows one to investigate the particle acceleration due to the action of three principal mechanisms: (1) plasma turbulence; (2) magnetic dipolarization; (3) their simultaneous action. For the given velocity kappa-distributions, we obtained energy spectra of three types of accelerated particles, i.e., protons p+, ions of oxygen O+, and electrons e–. It has been shown that the combined mechanism of dipolarization with turbulence (3) makes the largest contribution to the increase in the energy of protons and heavy ions as compared with a separate action of each of mechanisms (1) and (2); in this case, electrons accelerate less. The consideration of the joint action of acceleration mechanisms (1) and (2) can explain the apparition of particles with energies on the order of magnitude equal to hundreds keV in the Earth’s magnetosphere tail. 相似文献