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151.
Bacteria abundance, chlorophyll a, ATP and POC concentrations and respiration rates of microorganisms in the Changjiang Estuary and the plume were determined in July 1986. The high values of bacteria abundance occurred in the river mouth in association with suspended matter. It is assumed that bacteria were the major contributor to ATP and the main consumer of dissolved oxygen, and that the relationship between ATP and POC was present in that area. In the dilution zone (salinity; 25-30), instead of bacteria, phytoplankton was the major contributor to ATP and respiration rates, due to diatom bloom. Close relationships between Chi a and ATP, and ATP and POC were observed. Contribution of microbial carbon to POC was also estimated. 相似文献
152.
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
153.
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
154.
提出一种基于BP神经网络的结构破损诊断方法,该方法以结构破损前后柔度的变化作为破损诊断网络输入,为了解决由于系统响应样本数据空间分布不均匀对网络收敛速度及网络诊断影响问题,对网络训练样本采用广义空间格点进行了交换,模拟算例及应用实例均表明,本文方法能准确诊断结构破损位置与破坏程度,是一种有效的结构破损诊断方法. 相似文献
155.
鲽形目3亚目8科51属142种。鲀形目2亚目9科57属143种。海蛾鱼目1科2属3种,鮟鱇目3亚目11科23属41种。 相似文献
156.
Tiago M. Alves Vasilios Lykousis Dimitris Sakellariou Stamatina Alexandri Paraskevi Nomikou 《Geo-Marine Letters》2007,27(1):41-61
Bathymetric, 9.5-kHz long-range sidescan sonar (OKEAN), seismic reflection and sediment-core data are used in the analysis
of two tectonic troughs south of Crete, Eastern Mediterranean Sea. Here, up to 1.2 s two-way travel time (TWTT) of strata
have accumulated since the Middle Miocene in association with extension in the South Aegean region. The study area comprises
>100-km- long by >25-km-wide basins filled by sediments subdivided into two seismic units: (1) an upper Unit 1 deposited in
sub-basins which follow the present-day configuration of the southern Cretan margin; (2) a basal Unit 2, more than 500 ms
(TWTT) thick, accumulated in deeper half-graben/grabens distinct from the present-day depocentres. Both units overlap a locally
stratified Unit 3 comprising the pre-Neogene core complex of Crete and Gavdos. In this work, the interpreted seismic units
are correlated with the onshore stratigraphy, demonstrating that denudation processes occurring on Crete and Gavdos in response
to major tectonic events have been responsible for high sedimentation rates along the proximal southern Cretan margin. Consequently,
topographically confined sedimentary units have been deposited south of Crete in the last 12 Ma, including turbidites and
other mass-flow deposits fed by evolving transverse and axial channel systems. Surface processes controlling facies distribution
include the direct inflow of sediment from alluvial-fan systems and incising mountain rivers onto the Cretan slope, where
significant sediment instability processes occur at present. In this setting, seismic profiles reveal eight different types
of stratigraphic contacts on basin-margin highs, and basinal areas show evidence of halokinesis and/or fluid escape. The acquired
data also show that significant changes to the margin’s configuration occurred in association with the post-Alpine tectonic
and eustatic episodes affecting the Eastern Mediterranean. 相似文献
157.
史重光 《中国海洋大学学报(自然科学版)》1994,(Z2)
提出用于十二相可控整流器的8098单片机控制系统的电路原理和软件策略。包括自适应控制算法和触发相序计算在内的多种操作全部用软件实现.与通常的方法相比,此系统的成本更低,动态性能和静态性能更好。 相似文献
158.
Qiu Dahong Zang Jun Jia Ying
Academician of the Chinese Academy of Sciences Professor the State Key Laboratory of Coastal Offshore Engineering 《中国海洋工程》1996,(2)
Based on the 2nd order cnoidal wave theory, the characters of shallow water standing waves and their action on vertical walls are studied in this paper. The theoretical expressions of the wave surface elevation in front of and the wave pressure on the vertical wall are obtained. In order to verify the theoretical results, model tests were made in the State Key Laboratory of Coastal and Offshore Engineering at DUT. For the wave surface elevation in front of the wall and the wave forces on the wall at the moment when the wave surface at the wall surface goes down to the bottom of the wave trough, the calculated results coincide quite well with the experimental results. For the wave forces on the wall at the moment when the wave surface at the wall surface goes up to the top of the wave crest, the theoretical expressions are modified by the experimental results. For the convenience of practical use, calculations are made for the wave conditions which usually occur in enginering practice by use of the inves 相似文献
159.
研究了风浪频谱JONSWAP谱的峰度因子γ、尖度因子Pj和N谱尖度因子PN,参变量p,q间的关系;并在此关系上给出了由这两种谱计算的几个对应参量间的关系,在使用不同的谱形进行特征量的计算时,应注意不同频谱间的成长因子致性,以免引起计算结果的错误。 相似文献
160.
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