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831.
Measurements made with the charged particle spectrometer of the Max-Planck-Institut für Aeronomie onboard GEOS-1 were used to investigate the behaviour of energetic electrons and ions in the dusk sector of the magnetosphere. During substorms the integral ion flux ( 24 KeV) increased whereas the integral electron flux ( 20 KeV) first decreased and later on also increased. The dependences of these flux variations on pitch-angle and particle energy are described and discussed in terms of particle drift in the geomagnetic and geoelectric fields and adiabatic energy variations. The results also provide some information on the source region of the drifting particles. 相似文献
832.
The relative abundances of low energy ions (0.6–2.0 MeV/n) in solar energetic particle (SEP) and corotating interaction region (CIR) events have been measured by the EPAC experiment aboard Ulysses since launch in October 1990 until the present time. We give an overview of the abundances of heavy ions (He, C, Ne, Fe) relative to oxygen during energetic particle events lasting longer than 5 days during the in- and out-of-ecliptic phase of the mission. While the period Oct. 1990 to Aug. 1992 was dominated by high solar activity the Ulysses out of ecliptic passage at solar latitudes up to 45° went parallel to the declining phase of solar activity. Thus a very clear structure of corotating interaction regions was observed. While the in-ecliptic composition is in general agreement with measurements made near the Earth, the development of the CIR-composition shows two phases: From Aug. 1992 to May 1993 the C/O-ratio is 0.55–0.70, afterwards it increases to 0.8–0.9. This increase is correlated to the disappearance of the current sheet at 30° solar latitude reported by Smithet al. (1993). 相似文献
833.
HIGH TEMPERATURE MOIRE INTERFEROMETRY TECHNOLOGYZhangGuozhou;ZhuangYunan;B.S.J.Kang,WangFengxiang(Faculty403,BeijingUniversit... 相似文献
834.
N.U. Crooker J.T. Gosling V. Bothmer R.J. Forsyth P.R. Gazis A. Hewish T.S. Horbury D.S. Intriligator J.R. Jokipii J. Kóta A.J. Lazarus M.A. Lee E. Lucek E. Marsch A. Posner I.G. Richardson E.C. Roelof J.M. Schmidt G.L. Siscoe B.T. Tsurutani R.F. Wimmer-Schweingruber 《Space Science Reviews》1999,89(1-2):179-220
Corotating interaction regions (CIRs) in the middle heliosphere have distinct morphological features and associated patterns
of turbulence and energetic particles. This report summarizes current understanding of those features and patterns, discusses
how they can vary from case to case and with distance from the Sun and possible causes of those variations, presents an analytical
model of the morphological features found in earlier qualitative models and numerical simulations, and identifies aspects
of the features and patterns that have yet to be resolved.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
835.
O. Moullard R.G. Marsden T.R. Sanderson C. Tranquille R.J. Forsyth B.E. Goldstein 《Space Science Reviews》2001,97(1-4):289-292
We present and compare observations of energetic protons during the two first transits of the Ulysses spacecraft from low to high latitudes in the southern heliosphere. Protons in the energy range 1.8–3.8 MeV from the COSPIN
experiment are studied for global trends and in relation to some ambient structures in the solar wind (corotating interaction
region, forward/reverse shock). The global trends show the large dependence on the heliospheric condition and solar activity,
including indications of a larger ambient particle population during the rising phase of solar activity and more efficient
solar wind particle accelerators during the declining phase. More enhancements in the proton flux intensity are time associated
with forward shocks than reverse contrary to first pass. Recurrent structures are found even during the second transit. Some
latitude dependent periodicities are observed that could relate to the differential solar rotation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
836.
C. S. Fish C. M. Swenson G. Crowley A. Barjatya T. Neilsen J. Gunther I. Azeem M. Pilinski R. Wilder D. Allen M. Anderson B. Bingham K. Bradford S. Burr R. Burt B. Byers J. Cook K. Davis C. Frazier S. Grover G. Hansen S. Jensen R. LeBaron J. Martineau J. Miller J. Nelsen W. Nelson P. Patterson E. Stromberg J. Tran S. Wassom C. Weston M. Whiteley Q. Young J. Petersen S. Schaire C. R. Davis M. Bokaie R. Fullmer R. Baktur J. Sojka M. Cousins 《Space Science Reviews》2014,181(1-4):61-120
Funded by the NSF CubeSat and NASA ELaNa programs, the Dynamic Ionosphere CubeSat Experiment (DICE) mission consists of two 1.5U CubeSats which were launched into an eccentric low Earth orbit on October 28, 2011. Each identical spacecraft carries two Langmuir probes to measure ionospheric in-situ plasma densities, electric field probes to measure in-situ DC and AC electric fields, and a science grade magnetometer to measure in-situ DC and AC magnetic fields. Given the tight integration of these multiple sensors with the CubeSat platforms, each of the DICE spacecraft is effectively a “sensor-sat” capable of comprehensive ionospheric diagnostics. The use of two identical sensor-sats at slightly different orbiting velocities in nearly identical orbits permits the de-convolution of spatial and temporal ambiguities in the observations of the ionosphere from a moving platform. In addition to demonstrating nanosat-based constellation science, the DICE mission is advancing a number of groundbreaking CubeSat technologies including miniaturized mechanisms and high-speed downlink communications. 相似文献
837.
A hysteresis current-controlled pulsewidth modulation (PWM) scheme is simple and robust in switching control, but it is subject to not constant switching frequency. However, since its harmonic spectrum is not randomly distributed like those yielded by the random PWM (RPWM) scheme, the annoying harmonic effects still exist. A random switching control strategy is proposed here to let the harmonic spectrum of the hysteresis current-controlled PWM inverter be randomly distributed. First, the effect of varying band on the harmonic distribution characteristic of a hysteresis current-controlled PWM scheme is analyzed. Then a random hysteresis PWM scheme and its quantitative design procedure are proposed. Finally, a robust spectrum shaping technique is devised such that the desired harmonic distribution pattern can be achieved. In the resulting frequency spectrum, the magnitudes of lower frequency harmonics are shaped and reduced. Hence the inverter output with a better harmonic attribute is obtained. Validity of the proposed random hysteresis PWM scheme is verified by some simulated and measured results 相似文献
838.
An asymptotic analysis is presented for the ignition of a solid fuel that gasifies endothermically then reacts exothermically in the gas phase through a one-step Arrhenius process. The endothermic gasification was analyzed in an earlier paper; the present paper employs those results in treating the gas-phase reaction. It is shown that depending on values of the chemical parameters, the gas-phase ignition reaction may begin either at the time that gasification begins or during the later stage of transport-controlled gasification. In the former case, results for the gas-phase ignition time are similar to those for condensed-phase ignitions. In the latter case, a mixing layer develops in the gas-phase and moves away from the surface, the exothermic reaction being negligible until thermal runaway occurs somewhere within the mixing layer. Both early-time and late-time ignitions within the mixing layer are analyzed by solving partial differential equations derived from perturbations for large activation energies and a small ratio of gas to solid thermal responsivity. The theory serves to indicate how ignition by gas-phase reactions may be distinguished experimentally from ignition by condensed-phase or heterogenous reactions. 相似文献
839.
G. Tobie B. Giese T. A. Hurford R. M. Lopes F. Nimmo F. Postberg K. D. Retherford J. Schmidt J. R. Spencer T. Tokano E. P. Turtle 《Space Science Reviews》2010,153(1-4):375-410
The surface morphology of icy moons is affected by several processes implicating exchanges between their subsurfaces and atmospheres (if any). The possible exchange of material between the subsurface and the surface is mainly determined by the mechanical properties of the lithosphere, which isolates the deep, warm and ductile ice material from the cold surface conditions. Exchanges through this layer occur only if it is sufficiently thin and/or if it is fractured owing to tectonic stresses, melt intrusion or impact cratering. If such conditions are met, cryomagma can be released, erupting fresh volatile-rich materials onto the surface. For a very few icy moons (Titan, Triton, Enceladus), the emission of gas associated with cryovolcanic activity is sufficiently large to generate an atmosphere, either long-lived or transient. For those moons, atmosphere-driven processes such as cryovolcanic plume deposition, phase transitions of condensable materials and wind interactions continuously re-shape their surfaces, and are able to transport cryovolcanically generated materials on a global scale. In this chapter, we discuss the physics of these different exchange processes and how they affect the evolution of the satellites’ surfaces. 相似文献
840.
M.N. Gousheva R.P. Glavcheva D.L. Danov P.L. Hristov B.B. Kirov K.Y. Georgieva 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
The problem of earthquake prediction has stimulated the search for a correlation between seismic activity and ionospherical anomalies. We found observational evidence of possible earthquake effects in the near-equatorial and low latitude ionosphere; these ionospheric anomalies have been proposed by Gousheva et al. [Gousheva, M., Glavcheva, R., Danov, D., Angelov P., Hristov, P., Influence of earthquakes on the electric field disturbances in the ionosphere on board of the Intercosmos-Bulgaria-1300 satellite. Compt. Rend. Acad. Bulg. Sci. 58 (8) 911–916, 2005a; Gousheva, M., Glavcheva, R., Danov, D., Angelov, P., Hristov, P., Kirov, B., Georgieva, K., Observation from the Intercosmos-Bulgaria-1300 satellite of anomalies associated with seismic activity. In: Poster Proceeding of 2nd International Conference on Recent Advances in Space Technologies: Space in the Service of Society, RAST ‘2005, June 9–11, Istanbul, Turkey, pp. 119–123, 2005b; Gousheva, M., Glavcheva, R., Danov, D., Angelov, P., Hristov, P., Kirov, B., Georgieva, K., Satellite monitoring of anomalous effects in the ionosphere probably related to strong earthquakes. Adv. Space Res. 37 (4), 660–665, 2006]. This paper presents new results from observations of the quasi-static electric field and ion density on board INTERCOSMOS-BULGARIA-1300 satellite in the mid latitude ionosphere above sources of moderate earthquakes. Data from INTERCOSMOS-BULGARIA-1300 satellite and seismic data (World Data Center, Denver, Colorado, USA) for magnetically quiet and medium quiet days are juxtaposed in time-space domain. For satellite’s orbits in the time period 15.09–01.10.1981 an increase in the horizontal and vertical components of the quasi-static electric field and fluctuations of the ion density are observed over zones of forthcoming seismic events. Some similar post effects are observed too. The emphasis of this paper is put on the anomalies which specify the mid latitude ionosphere. The obtained results contain important information because they confirm our previous results for near-equatorial and low latitude regions. 相似文献