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151.
There is an urgent need for the development of a method that can undertake rapid, effective, and
accurate monitoring and identification of fog by satellite remote sensing, since heavy fog can cause
enormous disasters to China’s national economy and people's lives and property in the urban and coastal
areas. In this paper, the correlative relationship between the reflectivity of land surface and clouds in
different time phases is found, based on the analysis of the radiative and satellite-based spectral
characteristics of fog. Through calculation and analyses of the relative variability of the reflectivity in the
images, the threshold to identify quasi-fog areas is generated automatically. Furthermore, using the
technique of quick image run-length encoding, and in combination with such practical methods as
analyzing texture and shape fractures, smoothness, and template characteristics, the automatic
identification of fog and fog-cloud separation using meteorological satellite remote sensing images are
studied, with good results in application. 相似文献
152.
The changes in hydrological processes in the Yellow River basin were simulated by using the Community Land Model(CLM,version 3.5),driven by historical climate data observed from 1951 to 2008.A comparison of modeled soil moisture and runoff with limited observations in the basin suggests a general drying trend in simulated soil moisture,runoff,and precipitation-evaporation balance(P-E) in most areas of the Yellow River basin during the observation period.Furthermore,annual soil moisture,runoff,and P-E averaged over the entire basin have declined by 3.3%,82.2%,and 32.1%,respectively.Significant drying trends in soil moisture appear in the upper and middle reaches of the basin,whereas a significant trend in declining surface runoff and P-E occurred in the middle reaches and the southeastern part of the upper reaches.The overall decreasing water availability is characterized by large spatial and temporal variability. 相似文献
153.
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156.
A. P. Markeev 《Astronomy Letters》2005,31(5):350-356
We consider a periodic (in time) linear Hamiltonian system that depends on a small parameter. At a zero value of this parameter, the matrix of the system is constant, has two identical pairs of purely imaginary roots, and is not reducible to diagonal form. Therefore, the unperturbed system is unstable. We propose an algorithm for determining the boundaries of the instability regions for the system at nonzero values of the small parameter. This algorithm was used to analyze the stability of triangular libration points in the elliptical restricted three-body problem and in the stability problem in one special case of stationary rotation of a satellite relative to the center of mass. 相似文献
157.
In this paper we investigate the opportunities offered by the new Earth gravity models from the dedicated CHAMP and, especially, GRACE missions to the project of measuring the general relativistic Lense–Thirring effect with a new Earth’s artificial satellite. It turns out that it would be possible to abandon the stringent, and expensive, requirements on the orbital geometry of the originally prosed LARES mission (same semimajor axis a = 12,270 km of the existing LAGEOS and inclination i = 70°) by inserting the new spacecraft in a relatively low, and cheaper, orbit (a = 7500–8000 km, i 70°) and suitably combining its node Ω with those of LAGEOS and LAGEOS II in order to cancel out the first two even zonal harmonic coefficients of the multipolar expansion of the terrestrial gravitational potential J2, J4 along with their temporal variations , . The total systematic error due to the mismodelling in the remaining even zonal harmonics would amount to 1% and would be insensitive to departures of the inclination from the originally proposed value of many degrees. No semisecular long-period perturbations would be introduced because the period of the node, which is also the period of the solar K1 tidal perturbation, would amount to 102 days. Since the coefficient of the node of the new satellite would be smaller than 0.1 for such low altitudes, the impact of the non-gravitational perturbations of it on the proposed combination would be negligible. Then, a particular financial and technological effort for suitably building the satellite in order to minimize the non-conservative accelerations would be unnecessary. 相似文献
158.
O. G. Benvenuto † A. Brunini ‡ 《Monthly notices of the Royal Astronomical Society》2005,356(4):1383-1395
We present a numerical code for computing all stages of the formation and evolution of giant planets in the framework of the core instability mechanism. This code is a non-trivial adaption of the stellar binary evolution code and is based on a standard Henyey technique. To investigate the performance of this code we applied it to the computation of the formation and evolution of a Jupiter mass object from a half Earth core mass to ages in excess of the age of the Universe.
We also present a new smoothed linear interpolation algorithm devised especially for the purpose of circumventing some problems found when some physical data (e.g. opacities, equation of state, etc.) are introduced into an implicit algorithm like the one employed in this work. 相似文献
We also present a new smoothed linear interpolation algorithm devised especially for the purpose of circumventing some problems found when some physical data (e.g. opacities, equation of state, etc.) are introduced into an implicit algorithm like the one employed in this work. 相似文献
159.
三星定位性能分析及其与SINS的融合方法 总被引:1,自引:0,他引:1
针对三星定位技术,本文首先分析其定位算法,并推导其误差分布模型。同时根据输出信息的特点,给出三星定位与SINS(捷联惯性导航系统)进行组合的算法。然后,对三星定位系统的定位误差特性进行仿真试验,从而揭示该系统的误差分布特性。最后,对三星定位/SINS组合系统进行半实时的静态与动态试验,组合结果证明该组合系统定位精度良好,在中纬度区域接近于GPS的精度。 相似文献
160.