卫星电视授时系统及精度估计   总被引：1，自引：0，他引：1  

宋金安 《时间频率学报》1994,(Z1)

我国已建成短波、长波授时台，进行毫秒级、微秒级的时间服务．随着现代科技和经济的发展，上述方法已不能满足国家及国际交流的需要．本文提出卫星电视授时系统，同步卫星定位精度小于１１０ｍ，卫星授时精度为亚微秒。两原子钟利用卫星进行时刻同步，其精度与两原子钟的距离有关，相距３千多公里的两钟同步精度小于３５ｎｓ，相距数百公里的两原子钟同步精度小于２０ｎｓ  相似文献   

“气候跃变”对气候要素统计相关的影响     

李存强 《高原气象》1991,10(3):332-336

  相似文献   

海洋湍流的测量及相关分析     

李文娟  冷秀华  魏泽勋  沈宁  方国洪 《海洋科学》1996,20(5):34-38

对海洋湍流速度脉动的一维概率密度作了测量，并把测量结果与高 斯分布进行了比较。比较的结果表明，一个接近于高斯分布而另一个却差别较 大。计算到直至五阶湍流相关函数并与网格湍流进行了比较，结果都表明小时 间间隔中测量结果与网格湍流的结果近似一致，而大时间间隔中却相差很大。 以上结论说明了较长的测量时间的必要性。  相似文献   

南黄海表层沉积物天然湿容重和含水量的分布及其与粒度之间的关系   总被引：2，自引：0，他引：2  

徐善民 《海洋科学》1991,15(3):38-41

本文论述了南黄海表层沉积物天然湿容重和含水量的分布,并利用回归分析的方法讨论了容重和含水量与粒度之间的关系。结果表明,容重和含水量与粘土粒级相关性最好,容重与粘土粒级含量(相似文献   

海洋沉积物声速与物理参数的关系   总被引：4，自引：0，他引：4       下载免费PDF全文

卢博  梁元博 《海洋科学》1993,17(6):54-57

海洋沉积声速与物理性质密切相关，特别是含水量Ｗ和孔隙度Ｎ，它们在建立回归议程和预报沉积物性质中有所贡献。中国东，南海沿海沉积物的资料和数据表明：声速和声速比可以用来预报沉积物性质。  相似文献   

相空间反演方法在表层水温预报中的应用   总被引：4，自引：1，他引：4  

魏恩泊  田纪伟  李凤歧  苏育嵩 《海洋与湖沼》1997,28(3):315-319

利用相空间理论及方法对渤、黄、东海共4个站位近十几年的旬平均SST进行分析。结果表明：表层水温具有混饨特性，其吸引子关联维数平均约为1．23、嵌入相空间维数为6（渤、黄海）和7（东海178号站位）、二阶Renyi熵平均约为3．7×10-4（1／d）及平均可预报时间尺度平均为27个点；基于以上分析结果运用相空间反演方法建立了旬平均SST的反演模型，并且在试预报的前5旬的最大相对误差约为4．2％。  相似文献   

千里岩的气温变化特征及其与西北太平洋副热带高压的关系     

贾瑞丽  郭可彩 《海洋预报》1997,14(4):67-72

本文根据１９６０～１９９４年千里岩和青岛月平均气温资料，分析了千里岩与青岛３５年来气温的年、季变化特征及差别，发现３５年来，千里岩和青岛的年、季平均气温均呈变暖趋势，但千里岩增温幅度较青岛小。从分析中发现，与气温变暖趋势相对应，西北太平洋副热带高压（以下简称副高）面积、强度指数的年、季变化也呈明显的增强、增大趋势。且年平均气温与冬季副高面积指数相关最显著。最后依此关系建立回归方程，并预测了１９９６年千里岩年平均气温的变化趋势。  相似文献   

南极海冰与西北太平洋台风     

张林  薛振和 《海洋预报》1996,13(1):34-40

本文利用最大熵谱分别计算了南极４个区海冰和西北太平洋台风发生频数的变化周期，并对前３年的南极海冰强弱和当年的台风发生频率数进行了逐月时间序列相关分析。  相似文献   

Groundwater flow modeling for effective implementation of landslide stability enhancement measures     

H. K. Shrestha  R. Yatabe  N. P. Bhandary 《Landslides》2008,5(3):281-290

This paper deals with groundwater hydrology at a prominent fracture zone landslide slope (Nuta–Yone landslides) in Japan with an objective to explore an efficient method for the application of landslide stability enhancement measures. The correlation analyses between the hydrological parameters and ground surface movement data at this landslide resulted in low correlation values indicating that the geological formation of the area is extremely complex. For the purpose of understanding the groundwater flow behavior in the landslide area, a three-dimensional transient groundwater flow model was prepared for a part of the landslide slope, where the levels of effectiveness of applied landslide stability enhancement measures (in the form of multilayered deep horizontal drains) are different, and was calibrated against the measured water surface elevations at different piezometer locations. The parameter distributions in the calibrated model and the general directions of the groundwater flow in terms of flow vectors and the results of particle tracking at the model site were interpreted to understand the reasons for variations in effectiveness of existing landslide stability enhancement measures and to find potentially better locations for the implementation of future landslide stability enhancement measures. From the modeling results, it was also understood that groundwater flow model can be effectively used in better planning and locating the landslide stability enhancement measures.  相似文献   

Correlations in aftershock and seismicity patterns     

Robert Shcherbakov  Jordan Van Aalsburg  John B. Rundle  Donald L. Turcotte   《Tectonophysics》2006,413(1-2):53

Correlations in space and time play a fundamental role in earthquake processes. One direct manifestation of the effects of correlations is the occurrence of aftershocks due to the stress transfer in the vicinity of a main shock. Less obvious and more speculative changes in correlations may occur in the background seismicity before large earthquakes. Using statistical physics it is possible to introduce a measure of spatial correlations through a correlation length. This quantity characterizes how local fluctuations can influence the occurrence of earthquakes over distances comparable with the correlation length. In this work, the physical basis of spatial correlations of earthquakes is discussed in the context of critical phenomena and the percolation problem. The method of two-point correlation function is applied to the seismicity of California. Well defined variations in time of the correlation length are found for aftershock sequences and background seismicity. The scaling properties of our obtained distributions are analyzed with respect to changes in several scaling parameters such as lower magnitude cutoff of earthquakes, the maximum time interval between earthquakes, and the spatial size of the area considered. This scaling behavior can be described in a unified manner by utilizing the multifractal fit. Utilizing the percolation approach the time evolution of clusters of earthquakes is studied with the correlation length defined in terms of the radius of gyration of clusters. This method is applied to the seismicity of California.  相似文献