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321.
Recently, some results have been acquired with the Monte- Carlo statistical experiments in the design of ocean en gineering. The results show that Monte-Carlo statistical experiments can be widely used in estimating the parameters of wave statistical distributions, checking the probability model of the long- term wave extreme value distribution under a typhoon condition and calculating the failure probability of the ocean platforms. 相似文献
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By analysing the scatter diagrams of characteristic the wave height H and the period T on the basis of instrumental data from various ocean wave stations, we found that the conditional expectation and standard deviation of wave period for a given wave height can be better predicted by using the equations of normal linear regression rather than by those based on the log- normal law. The latter was implied in Ochi' s bivariate log-normal model(Ochi. 1978) for the long-term joint distribution of H and T. With the expectation and standard deviation predicted by the normal linear regression equations and applying proper types of distribution, we have obtained the conditional distribution of T for given H. Then combining this conditional P(T / H) with long-term marginal distribution of the wave height P(H) we establish a new parameterized model for the long-term joint distribution P(H,T). As an example of the application of the new model we give a method for estimating wave period associated with an extreme w 相似文献
324.
In this study the zinc exchange process and the reason for the non-additive exchange of δ-MnO2/montmorrillonite have been investigated. The results suggest that with pH increasing from 2 to 8, the stepwise exchange of zinc occurs on δ-MnO. and montmorrillonite in their mixture.At low pH zinc ions are bound on δ-MnO2, while at high pH, the exchange on montmorrillonite dominates the surface interaction in the mixture. The study demonstrates that the stepwise exchange and the heterogeneity of the binding sites on δ-MnO2 surface are the reason for the non-additive exchange. It is also shown that when δ-MnO2 amounts to 5 %, zinc exchange on sea sediments is controlled by 8-MnO2. 相似文献
325.
The vertical migration of diatoms in mud-flats was studied in littoral of Xibian, Longhai County and Xiao'ao, Lianjiang County, the dominant species being Gyrosigma spencerii and Hantzschia virgata respectively. Both light and tide are important factors affecting the vertical migration of diatoms. With the advent of tide, the diatom community disappears from the surface. It reappears gradually when exposed to light. In the dark, the diatoms never appear in great quantity on the surface in laboratory or in littoral. Whether in the light or in the dark, the diatoms aggregate in maximum numbers in the upper 2 mm of the sediment. But when the tide has covered the sediments for 4 hr, Hantz. virgata penetrates the mud down to a depth of 14 mm, Gy. spencerii, 12 mm. We have found that Gy. spencerii posseses phototaxis, but no tide rhythm and no day-night rhythm in our laboratory. 相似文献
326.
By using occanographic data (luring 1955-1978, we have analysed aspects of volume transport variation of the Kuroshio tor PN-linc in the East China Sea, and relationships between volume transport variation of the Kuroshio and the subtropical high pressure (SHP) of the Pacific. We have found that volume transport of the Kuroshio is closely related to the long-period oscillations of the subtropical high pressure for 8-9 years and 2-3 years, respectively. The subtropical high pressure has a phase lag behind compared with volume transport of the Kuroshio. In addition, the seasonal volume transport of the Kuroshio is closely related to the subtropical high pressure, too. The results show that volume transport variation of the Kuroshio has certain influence on future variation of the subtropical high pressure. Therefore, the volume transport of the Kuroshio may be an important parameter lor long-period forecasting of the subtropical high pressure. 相似文献
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研究了2003年10月采于珠江口5个站位的沉积物剖面酸挥发性硫化物(AVS)和同时提取的重金属(SEM:Pb,Zn,Cu,Cd,Ni)。其中,站位1、2位于中滩,其沉积物的AVS含量变化范围较小,为0.25—4.06μmol.g-1;站位3、4位于西滩,其沉积物的AVS含量变化范围较大,为0—26.09μmol.g-1。中滩和西滩沉积物的AVS含量均随深度增加。西滩表层沉积物的AVS含量接近于零,这可能与该水域较强的底层流和沉积物的再悬浮作用有关。站位5位于珠江口外侧,其表层沉积物的AVS含量相对较高,且垂向变化较小,可能是还原性沉积物间歇性再悬浮后重新沉积的结果。站位1、2和5沉积物中同时提取的重金属含量大体在0.95±0.2μmol.g-1范围内,随深度增加略呈下降趋势;而西滩沉积物重金属含量相对较高,为1.43—2.42μmol.g-1,且在一定深度范围内随深度增加呈明显下降的趋势,表明珠江口西滩沉积物中的重金属污染有加重的趋势。对AVS/SEM摩尔比值和单个金属的毒性效应研究显示,珠江口内尤其是西滩的表层沉积物存在重金属污染,对其中生活的底栖生物具有潜在的毒性效应。 相似文献
330.
Environmental control of growth and BChl a expression in an aerobic anoxygenic phototrophic bacterium, Erythrobacter longus (DSMZ6997) 总被引:1,自引:0,他引:1
1Introduction Aerobic anoxygenic phototrophic bacteria(AAPB) are facultative heterotrophs that can utilizelight for photosynthesis. These unique-functioningbacteria are widely distributed in marine environ-ments, such as coastal waters (Shiba et al., 1991… 相似文献