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121.
T. S. Bastian 《Space Science Reviews》1994,68(1-4):261-274
Radio and X-ray observations of stellar flares provide the most direct probes of energy relaase particle acceleration, and energy transport on stars other than the Sun. In this review, the observational basis for our understanding of the flare phenomenon on other stars is briefly described and outstanding interpretive and theoretical issues are discussed. I shall confine my attention to objects which are solar-like, to the extent that they possess deep convective envelopes and display activity which is presumed to be magnetic in origin. These include pre-main sequence objects, classical flare stars, and close binaries. Future directions are briefly discussed. 相似文献
122.
Carlson B.D. Evans E.D. Wilson S.L. 《IEEE transactions on aerospace and electronic systems》1994,30(1):109-115
For pt.I see ibid., vol.30, no.1, (Jan.1994). This paper describes the calculation of PF and PD for the Hough transform technique when the primary threshold crossings are weighted by their power before transforming (i.e., noncoherent integration). After expressions for PF and PD are derived, we examine the question of optimal granularity of the Hough accumulator space. We also investigate the relationship between primary and secondary thresholds and its effect on detectability 相似文献
123.
Glaser J.S. Witulski A.F. Myers R.G. 《IEEE transactions on aerospace and electronic systems》1994,30(1):135-143
A constant-frequency diode-clamped series resonant converter (CFCSRC) is proposed as a solution to problems associated with frequency-controlled resonant converters. This converter has two resonant frequencies, and control is achieved by varying the relative time spent at each switching frequency. Two zero-current-switching (ZCS) modes are examined and plotted in the output plane. An equation is given for the boundary between the two ZCS modes, as well as an expression for the boundary between ZCS and non-ZCS operation; both are plotted in the output plane. The output equation for the main mode is shown to be hyperbolic. Converter peak voltages limited to the input voltages, and peak currents are less than those of the frequency-controlled clamped series resonant converter over a large operating range. Data from a prototype converter are compared with theoretical data and are shown to be in good agreement with the theoretical model 相似文献
124.
125.
F.B. Rizzato A.C.-L. Chian M.V. Alves R. Erichsen S.R. Lopes G.I. de Oliveira R. Pakter E.L. Rempel 《Space Science Reviews》2003,107(1-2):507-514
Langmuir waves and turbulence resulting from an electron beam-plasma instability play a fundamental role in the generation
of solar radio bursts. We report recent theoretical advances in nonlinear dynamics of Langmuir waves. First, starting from
the generalized Zakharov equations, we study the parametric excitation of solar radio bursts at the fundamental plasma frequency
driven by a pair of oppositely propagating Langmuir waves with different wave amplitudes. Next, we briefly discuss the emergence
of chaos in the Zakharov equations. We point out that chaos can lead to turbulence in the source regions of solar radio emissions.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
126.
J. T. Gosling S. J. Bame D. J. McComas J. L. Phillips V. J. Pizzo B. E. Goldstein M. Neugebauer 《Space Science Reviews》1995,72(1-2):99-104
Ulysses plasma observations reveal that the forward shocks that commonly bound the leading edges of corotating interaction regions (CIRs) beyond 2 AU from the Sun at low heliographic latitudes nearly disappeared at a latitude of S26°. On the other hand, the reverse shocks that commonly bound the trailing edges of the CIRs were observed regularly up to S41.5°, but became weaker with increasing latitude. Only three CIR shocks have been observed poleward of S41.5°; all of these were weak reverse shocks. The above effects are a result of the forward waves propagating to lower heliographic latitudes and the reverse waves to higher latitudes with increasing heliocentric distance. These observational results are in excellent agreement with the predictions of a global model of solar wind flows that originate in a simple tilted-dipole geometry back at the Sun. 相似文献
127.
The solar wind termination shock is described as a multi-fluid phenomenon taking into account the magnetohydrodynamic self-interaction of a multispecies plasma consisting of solar wind ions, pick-up ions and shock-generated anomalous cosmic ray particles. The spatial diffusion of these high energy particles relative to the resulting, pressure-modified solar wind flow structure is described by a coupled system of differential equations describing mass-, momentum-, and energy-flow continuities for all plasma components. The energy loss due to escape of energetic particles (MeV) from the precursor into the inner heliosphere is taken into account. We determine the integrated properties of the anomalous cosmic ray gas and the low-energy solar wind. Also the variation of the compression ratio of the shock structure is quantitatively determined and is related to the pick-up ion energization efficiency and to the mean energy of the downstream anomalous cosmic ray particles. The variation of the resulting shock structure and of the solar wind sheath plasma extent beyond the shock is discussed with respect to its consequences for the LISM neutral gas filtration and the threedimensional shape of the heliosphere. 相似文献
128.
T.L. Zhang H. Zhao C.T. Russell S.M. Petrinec K. Schwingenschun W. Riedler 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(12):1943-1946
The northward and southward orientation of the interplanetary magnetic field (IMF) is usually considered as providing the external boundary conditions in the solar wind interaction with the Earth's magnetopause but it is the magnetic field in the magnetosheath that interacts with the Earth's magnetic field. In this paper, we consider the possibility that the wave activity in the foreshock region may affect the magnetic field orientation in the magnetosheath with time scales that might be geomagnetically effective. If magnetosheath magnetic field becomes disturbed on plasma streamlines which are connected to the quasi-parallel bow shock and foreshock, the magnetic field orientation on the inner magnetosheath may differ significantly from the undisturbed IMF. We present a model of dayside reconnection which may occur when the IMF northward and illustrate its effects on the erosion of the magnetopause. 相似文献
129.
G S Nechitailo A L Mashinsky 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(10):1959-1965
The results of experiments aboard spacecraft demonstrated the dependence of the pattern of biological processes on microgravity and on the ability of biological objects to adapt themselves to new environmental conditions. This is of fundamental importance for solving theoretical and practical problems of space biology, or elaborating the theory of organism's behavior in weightlessness, and for elucidating the global mechanisms of the action of microgravity on living systems. 相似文献
130.
M. M. Freund T. Hirao T. Matsumoto S. Sato T. Watabe G. K. Brubaker L. Duband B. Grossman N. Larkin S. Lumetta A. E. Lange 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1993,13(12):505-508
We describe the design and calibration of the Far-Infrared Photometer (FIRP), one of four focal plane instruments on the Infrared Telescope in Space (IRTS). The FIRP will provide absolute photometry in four bands centered at 150, 250, 400, and 700 μm with spectral resolution λ/Δλ ≈ 3 and spatial resolution ΔΘ = 0.5 degrees. High sensitivity is achieved by using bolometric detectors operated at 300 mK in an AC bridge circuit. The closed-cycle 3He refrigerator can be recycled in orbit. A 2 K shutter provides a zero reference for each field of view. More than 10% of the sky will be surveyed during the ≈3 week mission lifetime with a sensitivity of <10−13 W·cm−2·sr−1 per 0.5 degree pixel. 相似文献