共查询到20条相似文献,搜索用时 277 毫秒
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Thorsten Borrmann Horst Fichtner 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(12):2091-2101
A time-dependent, three-dimensional model of the dynamics of the heliosphere as a result of solar activity and a time-varying local interstellar medium is presented. The model is based on a recent version of the well known ZEUS code and employs parallel processing. It includes the solar and interstellar plasma components as well as neutral atoms, and contains the heliospheric magnetic field in a kinematic fashion. We study the dynamics of the heliosphere due to solar activity on periods of months to years up to the so-called Schwabe (11-year) cycle as well as due to time variations of the local interstellar medium, all of which have drawn increasing attention during recent years, as the significance of their direct or indirect effect on the Earth and its environment is under lively debate. 相似文献
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P. Morel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(6):15-20
The objectives of the World Climate Research Programme (WCRP) are expressed in terms of increasing time scales, from several weeks to several decades. The Programme calls for substantial developments in modelling the interaction of the global atmosphere with the ocean, land surface and sea-ice, as well as improved computations of radiation transfer in the presence of clouds, aerosols and absorbing gases. These developments require a large variety of space as well as surface based observations, and especially, additional efforts for systematic processing of available data to produce consistent records of significant climatological variables. The forthcoming development of a new generation of ocean observing satellites will be an essential component of the WCRP, as they will provide the data base for the large-scale oceanographic projects, the World Ocewan Circulation Experiment (WOCE) and the study of thew Tropical Ocean and the Global Atmosphere (TOGA). 相似文献
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N. Mridula Tarun Kumar PantC. Vineeth K. Kishore Kumar 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The general features of occurrence of an additional layer on the bottom side of F region, referred to as F0.5 layer in the pre noon period, over the magnetic equatorial location of Trivandrum (8.5° N; 77° E; dip lat of 0.5° N) in India during the period from 2004 to 2007 are presented using ionosonde observations. The F0.5 layer has a June (northern summer) solsticial maximum probability of occurrence with secondary maxima during December (northern winter) solstice. The seasonal as well as the day-to-day variability in the occurrence of F0.5 layer as mentioned in this paper seems to be a result of the variations in the amplitude and phases of the tides and gravity waves, and inventory of the metallic ions of meteoric origin. This study brings out an important manifestation of morning time F layer base region dynamics. 相似文献
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W. Elling H. Schwentek 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(4):33-36
Since 1958, daily temperature-height profiles have been measured up to 35–40 km at Berlin by means of radiosondes. An attempt is made here to describe these profiles as a function of the noon solar zenith angle, χ. It is shown that the basic annual variation of the measured profiles, T(h), can be presented as T(h) = To(h) cosn(h)χ. The subsolar temperature, To(h), and exponent, n(h), have been determined empirically from the summer and autumn data when the radiative balance is obviously dominant. Neither term depends on the solar cycle. Warmings in winter and coolings in spring are treated as disturbances in the annual variation, due to dynamics, and are described separately as ± ΔT(h). 相似文献
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薛立林 《北京航空航天大学学报》1998,24(6):692-694
为了给飞机提供一条能满足多种指标要求的最优飞行轨迹,针对变分最优理论难以求解多指标优化问题,提出了命名为多次优化的方法,即将多要求的优化任务分成先后相继的多次任务,每次任务中选取一种不能边界转化的要求作为最优性能指标,而其余要求转化为边界条件.利用这一方法以时间、转弯次数、转弯角度为最优性能指标给出了终端区最优飞行轨迹的一般特征. 相似文献
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M.M. Császár 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(4):309-312
Two procedure are presented for quantitative estimation of cloud cover (N), type of clouds (C), as well as base of clouds (Cb) and top of clouds (Ct) by using radiosonde data as well as satellite cloud pictures and radiation data. The data obtained in this way can be used as input data in the model for the estimation of the vertical profile of longwave radiative cooling. 相似文献
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C.T. Russell M.A. Saunders J.G. Luhmann 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(9):177-184
Despite its lack of an intrinsic magnetic field Venus has a well defined magnetotail, containing about 3 megawebers of magnetic flux in a tail about 4 RV across with perhaps a slightly elliptical cross section. This tail arises through the mass-loading of magnetic flux tubes passing by the planet. Mass-loading can occur due to charge exchange and photo-ionization as well as from the diffusion of magnetic field into the ionosphere. Various evidence exists for the mass-loading process, including the direct observation of the picked up ions with both the Venera and Pioneer Venus plasma analyzers. 相似文献
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E. Spencer S. Patra T. Asikainen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
In this paper, we have improved the capabilities of a low dimensional nonlinear dynamical model called WINDMI to determine the state of the global magnetosphere by employing the magnetotail (MT) index as a measurement constraint during large geomagnetic storms. The MT index is derived from particle precipitation measurements made by the NOAA/POES satellites. This index indicates the location of the nightside ion isotropic boundary, which is then used as a proxy for the strength of the magnetotail current in the magnetosphere. In Asikainen et al. (2010), the contribution of the tail current to the Dst index is estimated from an empirical relationship based on the MT index. Here the WINDMI model is used as a substitute to arrive at the tail current and ring current contribution to the Dst index, for comparison purposes. We run the WINDMI model on 7 large geomagnetic storms, while optimizing the model state variables against the Dst index, the MT index, and the AL index simultaneously. Our results show that the contribution from the geotail current produced by the WINDMI model and the MT index are strongly correlated, except during some periods when storm time substorms are observed. The inclusion of the MT index as an optimization constraint in turn increases our confidence that the ring current contribution to the Dst index calculated by the WINDMI model is correct during large geomagnetic storms. 相似文献
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目前综合飞行/火力控制主要研究从瞄准到武器投放的攻击过程,对进入段研究较少。采用手动控制为机翼非水平甩投轰炸方式创造攻击过渡点是非常困难的。进入段自动控制将会为其提供良好的攻击过渡点,并减轻飞行员操纵负担。它的核心问题是轨迹生成,因此,提出一种简化飞机质点运动模型和最短时间优化控制相结合的方法,生成进入段期望轨迹。该方法能够得到解析表达的期望轨迹参数,并能够满足轨迹生成的实时计算要求。数学仿真表明 相似文献
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H. Peter 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2007,39(12):1814-1825
The atmosphere of the Sun is highly structured and dynamic in nature. From the photosphere and chromosphere into the transition region and the corona plasma-β changes from above to below one, i.e., while in the lower atmosphere the energy density of the plasma dominates, in the upper atmosphere the magnetic field plays the governing role – one might speak of a “magnetic transition”. Therefore the dynamics of the overshooting convection in the photosphere, the granulation, is shuffling the magnetic field around in the photosphere. This leads not only to a (re-)structuring of the magnetic field in the upper atmosphere, but induces also the dynamic reaction of the coronal plasma, e.g., due to reconnection events. Therefore the (complex) structure and the interaction of various magnetic patches is crucial to understand the structure, dynamics and heating of coronal plasma as well as its acceleration into the solar wind.
The present article will emphasize the need for three-dimensional modeling accounting for the complexity of the solar atmosphere to understand these processes. Some advances on 3D modeling of the upper solar atmosphere in magnetically closed as well as open regions will be presented together with diagnostic tools to compare these models to observations. This highlights the recent success of these models which in many respects closely match the observations. 相似文献
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Borys Dabrowski Marek Banaszkiewicz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
The paper presents a method of determination an accurate position of a target (rover, immobile sensor, astronaut) on surface of the Moon or other celestial body devoid of navigation infrastructure (like Global Positioning System), by using a group of self-calibrating rovers, which serves as mobile reference points. The rovers are equipped with low-precision clocks synchronized by external broadcasting signal, to measure the moments of receiving radio signals sent by localized target. Based on the registered times, distances between transmitter and receivers installed on beacons are calculated. Each rover determines and corrects its own absolute position and orientation by using odometry navigation and measurements of relative distances and angles to other mobile reference points. Accuracy of navigation has been improved by the use of a calibration algorithm based on the extended Kalman filter, which uses internal encoder readings as inputs and relative measurements of distances and orientations between beacons as feedback information. The key idea in obtaining reliable values of absolute position and orientation of beacons is to first calibrate one of the rovers, using the remaining ones as reference points and then allow the whole group to move together and calibrate all the rovers in-motion. We consider a number of cases, in which basic modeling parameters such as terrain roughness, formation size and shape as well as availability of distance and angle measurements are varied. 相似文献
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S Grinfeld F Foulquier V Mitashov N Bruchlinskaia A M Duprat 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,17(6-7):237-240
In Urodele amphibians, the tail regenerates after section. This regeneration, including tissues as different as bone (vertebrae), muscle, epidermis and central nervous system (spinal cord), was studied in adult Pleurodeles sent aboard the russian satellite Bion 10 and compared with tail regeneration in synchronous controls. Spinal cord, muscle and cartilage regeneration occurred in space animals as in synchronous controls. One of the most important differences between the two groups was the pigmentation of the blastemas: it was shown in laboratory, to be not due to a difference in light intensity. 相似文献
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Exploring the Dynamic X-ray Universe:Scientific Opportunities for the Einstein Probe Mission 下载免费PDF全文
Time-domain astrophysics will enter a golden era towards the end of this decade with the advent of major facilities across the electromagnetic spectrum and in the multi-messenger realms of gravitational wave and neutrino. In the soft X-ray regime, the novel micro-pore lobster-eye optics provides a promising technology to realise, for the first time, focusing X-ray optics for wide-angle monitors to achieve a good combination of sensitivity and wide field of view. In this context Einstein Probe, a soft X-ray all-sky monitor mission, was proposed and selected as a candidate mission of priority in the space science programme of the Chinese Academy of Sciences. This paper reviews the most important science developments and key questions in this field towards 2020 and beyond, and how to achieve them technologically. It also introduces the Einstein Probe mission, including its key science goals and mission definition, as well as some of the key technological issues. 相似文献
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本文基于电离层突然骚扰对强太阳活动的依赖关系,用开环门限自回归分析方法,以每日最大2800MHz射电爆发峰值流量为预报因子,探讨短波衰退事件(SWF)的预报.通过对1980.1—6月和1980.1—2月的短波衰退事件作中、短期预报的检验,表明,用此方法作中期预报的效果优于经验方法的预报;用于短期预报(3天)效果较好. 相似文献
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