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1.
Ocean current forecasting is still in explorative stage of study. In the study, we face some problems that have not been met before. The solving of these problems has become fundamental premise for realizing the ocean current forecasting. In the present paper are discussed in depth the physical essence for such basic problems as the predictability of ocean current, the predictable currents, the dynamical basis for studying respectively the tidal current and circulation, the necessity of boundary model, the models on regions with different scales and their link. The foundations and plans to solve the problems are demonstrated. Finally a set of operational numerical forecasting system for ocean current is proposed. 相似文献
2.
作用于平台桩腿的海冰屈曲破坏冰压力随机过程模型及其参数确定 总被引:2,自引:1,他引:2
冰对结构的作用过程是典型的随机过程。本文在冰压力过程为平稳过程的假设下,从渤海海冰对平台桩腿作用的大量实测冰压力数据中,选取了21条冰屈曲破坏时的冰压力时程曲线,对它们进行谱分析后,得到了单点冰屈曲破坏的压力随机过程的谱密度,并确定了谱参数及其跟环境要素的关系,依据文献[1]中冰压力沿圆柱面的空间分布,建立了绕桩腿的冰压力随机场模型,并得到了作用于桩腿的总冰力随机过程及其谱密度。本文的研究成果为平台结构冰激随机振动和疲劳累积损伤分析提供了荷载基础 相似文献
3.
Practical implementation of Hilbert-Huang Transform algorithm 总被引:12,自引:0,他引:12
Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationary time series analysis. The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the wide application among the scientific community. Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition. The implementation of the HHT is realized in detail to widen the application. The detailed comparison of the results from two methods with that from Huang et al. (1998, 1999), and the comparison between two methods are presented. Generally, both methods reproduce faithful results as those of Huang et al. For mirror periodic method (MPM), the data are extended once forever. Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric waveform. The extrema extending method (EEM) behaves as good as MPM, and it is better t 相似文献
4.
Wu Jinping 《海洋学报(英文版)》1990,9(1):151-158
-Sediment from Xiamen industrial area was added to marine ecosystem enclosures to test the effects on the planktonic communities in Xiamen Bay, China, in April, 1985. Sediments were added at two concentrations, 11.2 and 112 ppm dry wt. respectively. The species of phytoplankton did not change as compared with the control, but the number of diatoms markedly decreased in the sediment treated enclosures. A suppression of photosynthesis was presumed to be due to light attenuation by the added sediment. Microflagellates, zooplankton and bacteria were resistant to sediment increase in water column. 相似文献
5.
在初步估算永城煤矿区的环境成本的基础上,对该矿区某矿井经济环境综合价值进行了评价和分析。当考虑矿区煤炭环境成本时,煤炭资源开采的净现值变小,该矿井煤炭资源开采的经济环境综合价值变小。进一步计算了不同环境成本和贴现率时的净现值,为动态决策服务。 相似文献
6.
Spatial-temporal Frame,Evolution and Mineralization of the Northern Qilian Metallogenic Province 总被引:1,自引:0,他引:1
Sun Haitian Wu Jieren Li Jinping Institute of Mineral Deposits Chinese Academy of Geological Sciences Beijing Xi''an Institute of Geology Mineral Resources Chinese Academy of Geological Sciences Xi''an Shaanxi Institute of Mineral Deposits Chinese Academy of Geological Sciences Beijing 《《地质学报》英文版》1997,71(2):204-216
Four metallogenic epochs occurred in different tectonic environments during theevolution of the Northern Qilian metallogenic province through the geological time. The Mid-dle Proterozoic metallogenic epoch witnessed the tectonic environment of crustal breakupcaused by mantle diapirism, in which ultramafic-mafic rocks were intruded along beep faultbelts and the superlarge Jinchuan magmatic Cu-Ni sulphide deposit was formed. In theMiddle-Late Proterozoic metallogenic epoch the crust was further broken to form anintracontinental rift, in which the Chenjiamiao style massive Cu-Fe sulphide deposits hosted bybasic volcanic tuff were formed in the lower volcano-sedimentary sequence, while the largesedex type Jingtieshan style Fe-Cu deposits were formed within the upper abyssal carbon-richargillaceous sedimentary sequence. The Early Palaeozoic saw the aulacogen environment, with-in which the Baiyinchang style superlarge massive base and precious metal sulphide depositshosted by quartz keratophyric tuff were formed in the Middle-Late Cambrian rifted island arcand the massive Cu-Zn sulphide deposits and magmatic chromite deposits associated with theophiolite suite were formed in the Early-Middle Ordovician, and the Honggou style massiveCu-Fe sulphide deposits hosted by spilite were formed in the Late Ordovician back-arc basinenvironment. In the Late Palaeozoic-Meso-Cenozoic, the metallogenic province went into anintracontinental orogenic stage characterized by compressive tectonic environment, in whichthere occurred carbonate-quartz vein type and tectono-alteration gold deposits associated withductile-shear structures. 相似文献
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9.
Although Eddy Covariance (EC) technique is one of the best methods for estimating the energy and mass exchanges between underlying surface and atmosphere in micrometeorology, errors and uncertainties still exist without necessary corrections. In this paper, we will focus on the effect of coordinate system on the eddy fluxes. Based on the data observed over four sites (one farmland site, one grassland site and two forest sites), the effects of three coordinate system transforming methods (Double Rotation-DR, Triple Rotation-TR and Planar Fit-PF)on the turbulent fluxes are analyzed. It shows that (i) the corrected fluxes are more or less than the uncorrected fluxes, which is related mainly to the sloping degree of surface, wind speed and wind direction; and (ii) pitch angle has a sinusoidal dependence on wind direction, especially in the regular sloping terrain; and (iii) PF method is something like the simplification of TR or DR,and there are not obvious distinctions in correction in sloping grassland and flat farmland, but PF method is not suitable for uneven and irregular forest sites. 相似文献
10.
A simulated experimental reduction of U^v1 and the synthesis of uraninite by a sulfate-reducing bacteria,Desulfovibrio desulfuricans DSM 642, are first reported. The simulated physicochemical experimental conditions were:35℃, pH=7.0-7.4, corresponding to the environments of formation of the sandstone-hosted interlayer oxidation-zone type uranium deposits in Xinjiang, NW China. Uraninite was formed on the surface of the host bacteria after a one-week‘s incubation. Therefore, sulfate-reducing bacteria, which existed extensively in Jurassic sandstone-producing environments,might have participated in the biomineralization of this uranium deposit. There is an important difference in the orderdisorder of the crystalline structure between the uraninite produced by Desulfovibrio desulfuricans and naturally occurring uraninite. Long time and slow precipitation and growth of uraninite in the geological environment might have resulted in larger uraninite crystals, with uraninite nanocrystals arranged in order, whereas the experimentally produced uraninite is composed of unordered uraninite nanocrystals which, in contrast, result from the short time span of formation and rapid precipitation and growth of uraninite. The discovery has important implications for understanding genetic significance in mineralogy, and also indicates that in-situ bioremediation of U-contaminated environments and use of biotechnology in the treatment of radioactive liquid waste is being contemplated. 相似文献