Evaluation on the two filling functions for the recovery of forest information in mountainous shadows on Landsat ETM + Image   总被引：1，自引：0，他引：1  

SHAHTAHMASSEBI Amir reza  MOORE Nathan 《山地科学学报》2011,8(3):414-426

In general,topographic shadow may reduce performance of forest mapping over mountainous regions in remotely sensed images.In this paper,information in shadow was synthesized by using two filling techniques,namely,roifill and imfill,in order to improve the accuracy of forest mapping over mountainous regions.These two methods were applied to Landsat Enhanced Thematic Mapper (ETM +) multispectral image from Dong Yang County,Zhejiang Province,China.The performance of these methods was compared with two conventi...  相似文献   

Hawking radiation from rotating AdS black holes in conformal gravity     

Shuang-Qing Wu  Gao-Ming Deng  Di Wu 《Astrophysics and Space Science》2014,352(2):751-762

We extend to study Hawking radiation via tunneling in conformal gravity. We adopt Parikh-Wilczek’s semi-classical tunneling method and the method of complex-path integral to investigate Hawking radiation from new rotating AdS black holes in conformal gravity. In this paper, the research on Hawking radiation from the rotating black holes is done in a general system, not limited in dragging coordinate systems any longer. Moreover, there existed some shortcomings in the previous derivation of geodesic equations. Different from the massless case, they used a different approach to derive the geodesic equation of the massive particles. Even the treatment was inconsistent with the variation principle of action. To remedy the shortcoming, we improve treatment to deduce the geodesic equations of massive and massless particles in a unified and self-consistent way. In addition, we also recover the Hawking temperature resorting to the complex-path integral method.  相似文献   

Some tests and improvements to the VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager     

Fei Teng  Yuan-Yong Deng 《中国天文和天体物理学报》2014,(11)

Some experimental tests and improvements to the Very Fast Inversion of the Stokes Vector program, which is designed for the inversion calculation used by the Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory,are given. On one hand, the interpolation for calculating the Voigt function is not smooth, which may occasionally cause the iteration process to converge to different minima although they are very close to initial values. This problem can be solved by a smoother interpolation. On the other hand, in order to improve the performance of this program, we have tried to abandon the randomly-jump-out strategy and set the initial value properly to avoid non-global minima. The resulting method costs only1/4 of the computational time, and will be very competitive when the users are only interested in the vectorial magnetic fields and the velocities along the line of sight.  相似文献   

江西省中小水电智慧气象服务技术研究及应用效果检验          下载免费PDF全文

谢克勇  张勇平  邓德文  毕晨  李三角 《气象与减灾研究》2021,44(2):152-158

基于高精度DEM及水系数据的流域集雨区划分,研究了江西省中小水电站集雨区划定技术方法;通过对水库集雨区上降水预报和观测站点的实况两者对比分析,建立了基于库区的多模式本地化水库面雨量预报方法;通过模式参数化率定方法以及雨洪耦合来水量预报方法的研究,建立了水库来水量预报模型.利用2007—2020年水文数据以及降水实况和模式数据,检验了七一水库2020年逐7 d面雨量预报效果.检验结果表明,面雨量预报模型在0—3 d的平均预报准确率为70.1％;中雨和大雨量级的降水预报准确率分别为30.7％和28.3％,暴雨、大暴雨预报具有一定的指示意义;改进后的流量模拟效果进一步提升,强降水过程的流量预报效果明显改善.  相似文献   

High-velocity features in the spectra of the Type Ia supernova SN 1999ee: a property of the explosion or evidence of circumstellar interaction?     

P. A. Mazzali  S. Benetti  M. Stehle  D. Branch  J. Deng  K. Maeda  K. Nomoto  M. Hamuy 《Monthly notices of the Royal Astronomical Society》2005,357(1):200-206

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GS型重力仪的静电反馈与静电标定     

邓涛  罗星辉 《大地测量与地球动力学》1993,(3)

本文介绍了静电反馈及静电标定技术在GS型重力仪上的具体应用,着重阐述了它的工作原理。应用结果表明,装配有静电反馈及静电标定系统的重力仪,不但观测资料精度大大提高,而且仪器的标定既简单又准确。  相似文献   

独立变量频率法计算P—T大气稳定度频率及其误差分析与订正     

孟庆珍  邓新民  郭宇宏  吴桂先 《成都信息工程学院学报》1992,(1)

本文把确定大气稳定度的因子:太阳高度角、云量和风速看作相互独立的变量,并用韦伯分布拟合风频,通过计算三个独立变量的频率的方法计算大气稳定度频率。成都地区实例计算表明,该法与传统的P-T法统计结果十分吻合,但却具有所需资料少,计算工作量小等明显优点,通过对该法的误差进行分析,提出合理的订正方法,得出精确的订正结果。并提出更精确的三参数风频拟合设想。通过与传统P-T法比较,指出了传统P-T法风速分级与实测风速整数取值之间的矛盾,给出了切实可行的解决方法。  相似文献   

大质量恒星演化的若干问题(英文)     

邓李才 《紫金山天文台台刊》2003,(2)

大质量恒星由于其高光度、短寿命和质量损失 ,对星系的积分光谱能量分布和重元素增丰起主导作用 ,从而在研究星系的形成和演化上具有特殊的意义。特别是随着天文设备的长足进展 ,我们可以回溯宇宙演化的历史 ,得到形成初期时星系的观测性质。那时 ,大质量恒星主导星系的辐射性质 ,这更加突出了对大质量恒星进一步了解的迫切性。但是大质量恒星的演化性质相对中小质量恒星而言 ,有很多不确定性。本文通过对比现有恒星模型与实测结果 ,对现有大质量恒星演化理论中存在的几个与对流和质量损失相关的问题进行了评述 ,并对从理论上 ,特别是通过数字模拟方法对这些问题进行诊断提出了展望。  相似文献   

Large-scale two-dimensional distribution of extragalactic IRAS faint sources     

Liu Bin  Wang Gang  Xia Xiao-yang  Deng Zu-gan   《Chinese Astronomy and Astrophysics》1994,18(4):383-392

For four selected fields in the Catalogue of IRAS Faint Sources we have calculated the two-point correlation function of the galaxies and the correlation fractal dimension. The results show that the galaxies in all the fields are clustered on small angular scales. On larger scales, the distribution can be well expressed by a multi-level fractal. On still larger scales, possible typical scales can be detected using un-normalized pair counts. The average results for the four fields are consistent with previous results for the all-sky IRAS point sources and other sky surveys.  相似文献   

Structural analysis of FAST reflector supporting system     

Y.F. Luo  C.G. Deng  G.Q. Li  Y.M. He 《Astrophysics and Space Science》2001,278(1-2):231-236

According to the deformation and movement requirements of the FAST reflector, a multi-purpose analysis, including the load-bearing behavior, deformation, construction costs of the reflector supporting structure and its model, is presented in this paper. The advantages and disadvantages of steel and aluminum alloy structures are also discussed and compared through detailed design calculations under load-bearing capacity and normal working conditions. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献