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121.
日月食等天文现象使日、月球对地球的引潮力迅速增长,从而影响天气气候的变化,经分析表明,日月食与当年川东盛夏旱涝气候的发生关系密切。利用日月食出现日期、运行轨迹在若干年前就可以计算出来,信息来源特别超前的这一特点,制作出21世纪初气候预测。预计:21世纪初的前10年,川东有6年为伏旱年,4年为轻或无伏旱年。 相似文献
122.
针对地基卫星测控系统(Tracking Telemetry and Command, TT&C)系统对地球静止轨道(Geostation-\lk ary Earth Orbit, GEO)卫星在空间和时间覆盖上的局限性, 提出小倾角低地球轨道(Low Earth Orbit, LEO)多星组网天基平台对GEO卫星进行跟踪定轨的方法. 根据空间环境和光学可视条件对仿真数据进行筛选以模拟真实的观测场景, 利用光学测角数据, 使用数值方法对GEO卫星的轨道进行确定. 结果与参考轨道进行重叠对比, 在平台轨道精度5 m、测量精度5rq\rq、 定轨弧长12 h的情况下, 两颗LEO卫星对GEO卫星进行跟踪定轨的精度可达到千米量级, 4颗LEO卫星对GEO目标进行跟踪定轨的精度可达到百米量级. 随着LEO组网卫星数量的增加, 定轨精度得到了较大的提高. 相似文献
123.
124.
月海玄武岩与月球演化 总被引:6,自引:0,他引:6
月海玄武岩主要产于月球近边的盆地中,覆盖面积为月球表面的l%,其形成年龄多在39~31亿年之间,是各类月岩中最年轻的。与地球玄武岩相似,月海玄武岩由斜长石、辉石和橄榄石组成,但它们比地球玄武岩具有更低的Mg#、A1:0,、K和Na含量.高的FeO含量(大于16%)和变化范围大的TiO2含量(小于l%到大于13%)。根据TiO2含量的变化,月海玄武岩分成高Ti(〉6%),低Ti(1.5%〈TiO:〈6%)以及极低Ti(〈1.5%)三类。所有月海玄武岩都具有Eu负异常,并亏损挥发性元素和亲铁元素。月海玄武岩的同位素特征指示其至少为三个组分混合的产物:(1)高:238U/204Pb、高87Sr/86Sr和负εNd组分,可能是岩浆海分异的残余岩浆即KREEP;(2)低:238U/204Pb、低87Sr/86sr和正εNd组分,来源于原始月幔,其熔融产物为低Ⅱ玄武岩;(3)中等87Sr/86Sr和εNd组分,位于月幔的顶部,经历了岩浆海(洋)过程中形成的堆晶物质的再熔融,还可能受到了陨击事件的影响,其熔融产物是高Ti玄武岩。月海玄武岩的元素和同位素地球化学性质支持岩浆海的假说,其源区的形成与岩浆海的分异密切相关,并经历了三个阶段:(a)岩浆海阶段,通过岩浆海的结晶分异形成顶部为斜长岩月壳,中间为高Ⅱ、富钛铁矿层,底部为巨厚的硅酸盐低Ti层的三层壳幔结构;(b)富钛铁矿堆晶岩(携带少量残余熔体)因密度大而下沉至下部的硅酸盐月幔(400km以下);(C)月幔中这些不同源区的岩石发生减压熔融。早期由较浅的低熔点组分熔融形成低K高Ti玄武岩,之后形成来源较深的高Ti玄武岩和低Ti玄武岩。 相似文献
125.
基于对 2 0世纪中国大陆 7.0级以上大地震与月亮白赤交角的变化和太阳活动的研究结果 ,根据对未来 50a (年 )月亮白赤交角的值与目前太阳活动的形势 ,提出 2 1世纪中国大陆第一个大地震活动幕可能是 2 0 0 6或 2 0 0 7~ 2 0 1 5年 相似文献
126.
K. Torkar M. V. Veselov V. V. Afonin H. Arends M. Fehringer G. Fremuth K. Fritzenwallner Y. I. Galperin A. I. Kozlov A. Pedersen S. Perraut W. Riedler F. Rüdenauer R. Schmidt A. Smit N. Valavanoglou L. V. Zinin 《Annales Geophysicae》1998,16(9):1086-1096
The satellite INTERBALL-2 has an orbit with high inclination (62.8°), covering the altitude range between a few hundred and about 20000 km. The ambient plasma conditions along this orbit are highly variable, and the interactions of this plasma with the spacecraft body as well as the photo-electron sheath around it are considered to be interesting topics for detailed studies. The electric potential of the spacecraft with respect to the ambient plasma that develops as a result of the current equilibrium reacts sensitively to variations of the boundary conditions. The measurement and eventual control of this potential is a prerequisite for accurate measurements of the thermal plasma. We describe the purpose and technical implementation of an ion emitter instrument on-board INTERBALL-2 utilising ion beams at energies of several thousand electron volts in order to reduce and stabilise the positive spacecraft potential. First results of the active ion beam experiments, and other measures taken on INTERBALL-2 to reduce charging are presented. Furthermore, the approach and initial steps of modelling efforts of the sheath in the vicinity of the INTERBALL-2 spacecraft are described together with some estimates on the resulting spacecraft potential, and effects on thermal ion measurements. It is concluded that even moderate spacecraft potentials as are commonly observed on-board INTERBALL-2 can significantly distort the measurements of ion distribution functions, especially in the presence of strongly aniso-tropic distributions. 相似文献
127.
华北地区地震活动的月相效应及其预测意义 总被引:5,自引:0,他引:5
对华北地区1970年以来ML4.0以上地震的月相效应进行了分析。结果表明,华北地区Ms5.0以上地震活动的月相效应并不明显,而是呈现较强的随机性。但在7级以上强震发生前,中等地震的发生具有较为明显的月相效应,这对7级以上强震的发生具有中期(1~3年)预测意义。未来强震可能发生在“朔望地震”分布的地区。目前,华北地区中等地震发生没有显示明显的月相效应,因此未来1~2年内华北地区发生7级以上地震的可能性较小。 相似文献
128.
Scientific objectives and payloads of Chang’E-1 lunar satellite 总被引:1,自引:0,他引:1
Sun Huixian Dai Shuwu Yang Jianfeng Wu Ji Jiang Jingshan 《Journal of Earth System Science》2005,114(6):789-794
China plans to implement its first lunar exploration mission Chang’E-1 by 2007. The mission objectives are
To achieve the above mission goals, five types of scientific instruments are selected as payloads of the lunar craft. These
include stereo camera and spectrometer imager, laser altimeter, microwave radiometer, gamma and X-ray spectrometers and space
environment monitor system. In order to collect, process, store and transmit the scientific data of various payloads a special
payload data management system is also included. In this paper the goals of Chang’E-1 and its payloads are described 相似文献
– | • to obtain a three-dimensional stereo image of the lunar surface, |
– | • to determine distribution of some useful elements and to estimate their abundance |
– | • to survey the thickness of lunar soil and to evaluate resource of3He and |
– | • to explore the environment between the Moon and Earth. |
129.
130.
Environmental influences on temporal patterns of settlement in two littoral labrid fishes in the Mediterranean Sea 总被引:1,自引:1,他引:1
Correlations between daily fish settlement and environmental and physical parameters were examined during two consecutive years in two labrid species (Symphodus roissali and Symphodus ocellatus) in the NW Mediterranean Sea. Both these species have a short planktonic larval duration (12±0.3 and 9±0.4 days, respectively) and limited offshore larval dispersal. Time-series analysis was used to compare the daily settlement patterns with various environmental variables, and non-linear generalized additive models (GAM) were used to examine the relationship between environmental conditions averaged over larval period and daily settlement patterns. Settlement was not uniform and took place as pulses of different length. Although the analyses detected a few significant correlations between day-to-day patterns in environmental variables and settlement (e.g. solar radiation, atmospheric pressure, daytime or nocturnal wind components), these were not consistent among years. In S. ocellatus, however, wind components (daytime or nighttime) explained part of the variance in settlement intensity. The correlations (GAM outputs) observed between settlement patterns and environmental variables (averaged during the whole planktonic period) suggest that calm weather during the planktonic period usually increases settlement success. 相似文献