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561.
T. Hirayama 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(6):914-925
In this paper we present a new mechanism of the main energy conversion of the solar flare. Since a flare inducing prominence (flux tube) rises Vz ? 300 km s−1, the plasmas below it cannot continuously eject with Alfvén speeds of VA = 3000 km s−1 but probably with Vz ≈ ±100 km s−1. Plasma up and downflows with VA will within a short duration be blocked between the chromosphere where reconnected flux tubes are piling up, and the slowly rising flux rope. Hence the Petschek slow shock mechanism is difficult to be realized as a major energy converting mechanism. 相似文献
562.
T.K. Yeoman H.C. Scoffield D.M. Wright L.J. Baddeley A.N. Vasilyev N.V. Semenova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
A brief review is provided of recent progress in understanding the ionospheric Alfvén resonator (IAR) at high latitude. Firstly, naturally occurring resonances of the IAR as detected by pulsation magnetometers in the auroral zone at Sodankylä and in the polar cap at Barentsburg are considered. The characteristics of the IAR in the two regions are broadly similar, although the effects of solar illumination are less clear at the higher latitudes. Secondly we review recent attempts to stimulate the IAR through high-power radio frequency experiments both in the auroral zone at Tromsø with the European Incoherent SCATter (EISCAT) heater, and within the polar cap at Longyearbyen with the Space Plasma Exploration by Active Radar (SPEAR) facility. In the auroral zone at, Tromsø the stimulated IAR has been observed by ground-based magnetometers, and through electron acceleration observed on the FAST spacecraft. At SPEAR in the polar cap, the stimulated IAR has been investigated, with ground magnetometers, with the first results indicative of a positive detection. 相似文献
563.
Sven Kühl Janis Pukite T. Deutschmann Ulrich Platt Thomas Wagner 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) measures scattered sun light also in limb viewing mode (i.e. tangential to Earth’s surface and its atmosphere), which allows determining vertical profiles of atmospheric trace gases. First results on the retrieval of NO2, BrO and OClO profiles from the SCIAMACHY Limb measurements are presented and compared to independent satellite and balloon borne observations. 相似文献
564.
R.C. Elphic T.J. Kelly C.T. Russell 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(4):131-134
Magnetic field measurements obtained in the nightside magnetosphere by the co-orbiting ISEE-1 and 2 spacecraft have been examined for signatures of field-aligned currents (FAC). Such currents are found on the boundary of the plasma sheet both when the plasma sheet is expanding and when it is thinning. Plasma sheet boundary layer current structure and substorm associated dynamics can be determined using the two spacecraft, although for slow traversals of the FAC sheet the spatial/temporal ambiguity is still an issue. We often find evidence for the existence of waves on the plasma sheet boundary, leading to multiple crossings of the FAC sheet. At times the boundary layer FAC sheet orientation is nearly parallel to the X-Z GSM plane, suggesting ‘protrusions’ of plasma sheet into the lobes. The boundary layer current polarity is, as expected, into the ionosphere in the midnight to dawn local time sector, and outward near dusk. Current sheet thicknesses and velocities are essentially independent of plasma sheet expansion or thinning, having typical values of 1500 km and 20–40 km/s respectively. Characteristic boundary layer current densities are about 10 nanoamps per square meter. 相似文献
565.
There have been two new algorithms of fairly recent origin offered for the calculation of the matrix pseudoinverse. Unfortunately, nonpathological counterexamples can be constructed, as offered herein, that demonstrate the questionable nature of these two algorithms; however, a resolution is offered here to help prevent possible uncritical propagation of the questionable algorithms. As a rigorous alternative, a well-established technique (endorsed by numerical analysts) is reviewed for calculating the correct matrix pseudoinverse using a computer. Additionally, this technique possesses existent independently verified/validated and assessible software code for a convenient implementation. However, historical loose ends in calculating the associated condition number are singled out here as cause for concern and as a topic for future resolution and refinement. Finally, as the primary motivation for considering these issues, an application example is offered from estimation theory in the implementation and analysis of a minimum variance reduced-order (MVRO) filter having proper performance that critically hinges on the correct computation of the matrix pseudoinverse. While examples of applying MVRO to navigation applications were provided almost a decade ago, a clear indication of the somewhat restrictive conditions of applicability were wanting and so are elucidated here since there appears to be a resurgence of interest in this analytic technique. Another contribution is in providing a tally of the drawbacks to be incurred in using MVRO as well as its previously publicized benefits. 相似文献
566.
Hardware-in-the-loop testing technology for automatic control, condition monitoring and diagnostics systems of gas turbine engines is described. The technology proposed makes it possible to simulate combinations and chains of unexpected and gradual failures of engines, transducers and actuators. 相似文献
567.
I. Sh. Sharafeev 《Russian Aeronautics (Iz VUZ)》2009,52(2):255-258
A set of systems for labor standard computer-aided design is described, namely, initial developments, advance and state-of-the art. 相似文献
568.
Some experimental data on the process of impulsive ultrasonic machining are presented. Also given are the data on variations in the impulsive vibration frequency of a workpiece and a tool. 相似文献
569.
T Takakura E Goto M Tanaka 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(4-5):255-258
An axis clinostat was constructed to create micro and negative gravity also a rotated flat disk was constructed with different rotation rates to give increased gravity, by centrifugal force up to 48 g. Rice seeds were grown on agar in tubes at the constant air temperature of 20 degrees C under an average light condition of 110 micromol/m2/sec(PPF). Humidity was not controlled but was maintained above 90%. Since the tube containers were not large enough for long cultivation, shoot and root growth were observed every 12 hours until the sixth day from seeding. The lengths of shoots and roots for each individual plant were measured on the last day. The stem lengths were increased by microgravity but the root lengths were not. Under the negative gravity, negative orthogeotropism and under microgravity, diageotropism was observed. No significant effect of increased gravity was observed on shoot and root growth. 相似文献
570.
Miller D.L. Wolfman G.J. Volanth A.J. Mullins R.T. 《Aerospace and Electronic Systems Magazine, IEEE》1996,11(4):22-26
Tower air traffic control is currently performed using several unintegrated systems. While each of these systems supports performing an isolated task, the compilation of tools presents a number of challenges. This paper reports ways in which the Tower Control Computer Complex (TCCC) will support and enhance user management of numerous systems. Areas that will be notably improved include the consistency in the user interface of the air traffic control toolset, the task of manually integrating tools and information, toolset alert management, and toolset organization and administration 相似文献