藏南白垩系黑-红层沉积岩有机质组成分布特征   总被引：1，自引：0，他引：1  

傅培刚  宋之光  胡修棉  王成善 《地质学报》2008,82(1):85-91

对藏南江孜县床得剖面白垩系黑层和红层沉积岩进行的有机地球化学研究表明,黑层有机碳含量高于红层5～10倍,红层和黑层饱和烃主峰碳数分别为nC25和nC23;黑层和红层沉积有机质的母质来源都以水生植物和菌藻类等低等生物为主,陆源有机质的输入非常有限;但饱和烃的分布和主峰碳数的差异可能反映了有机母源物质在种群方面的差异,而这种差异可能主要是水体温度存在差异造成的,即红层发育时期水体温度可能高于黑层沉积时期.而在高温度条件下,水生生物和陆生植物的生长发育受到限制,造成原始有机质产率和有机质沉积保存量低可能是红层沉积岩形成的主要原因.  相似文献   

Monitoring Large-Scale Tests for Nuclear Waste Disposal     

Eduardo E. Alonso  Sarah M. Springman  Charles W. W. Ng 《Geotechnical and Geological Engineering》2008,26(6):817-826

Two large-scale “in situ” demonstration experiments and their instrumentation are described. The first test (FEBEX Experiment) involves the hydration of a compacted bentonite barrier under the combined effect of an inner source of heat and an outer water flow from the confining saturated granite rock. In the second case, the progressive de-saturation of Opalinus clay induced by maintained ventilation of an unlined tunnel is analyzed. The paper shows the performance of different sensors (capacitive cells, psychrometers, TDR’s) and a comparison of fill behaviour with modelling results. The long term performance of some instruments could also be evaluated specially in the case of FEBEX test. Capacitive sensors provide relative humidity data during long transient periods characterised by very large variations of suction within the bentonite.  相似文献   

PSO-RBFNN模型及其在岩土工程非线性时间序列预测中的应用   总被引：1，自引：0，他引：1  

梁桂兰  徐卫亚  何育智  赵延喜 《岩土力学》2008,29(4):995-1000

岩土工程受力变形演化是一个典型的非线性问题,其演化的高度非线性和复杂性,很难用简单的力学、数学模型描述,但可用粒子群优化径向基神经网络对岩土工程应力、位移非线性时间序列进行动态实时预测。网络径向基层的单元数通过均值聚类法确定后,所有其它参数：中心位置、形状参数、网络权值,均通过粒子群优化算法在全局空间优化确定。工程实例应用表明,该模型预测结果准确、精度高,有良好的应用前景。  相似文献   

Effect of Cyclic Loading Frequency on Undrained Behaviors of Undisturbed Marine Clay   总被引：2，自引：0，他引：2  

陈云敏  姬美秀黄博 《中国海洋工程》2004,18(4):643-651

Based on a series of cyclic triaxial tests, the effect of cyclic frequency on the undrained behaviors of undisturbed marine clay is investigated. For a given dynamic stress ratio, the accumulated pore water pressure and dynamic strain increase with the number of cycles. There exists a threshold value for beth the accumulated pore water pressure and dynamic strain, below which the effect of cyclic frequency is very small, but above which the accumulated pore water pressure and dynamic strain increase intensely with the decrease of cyclic frequency for a given number of cycles. The dynamic strength increases with the increase of cyclic frequency, whereas the effect of cyclic frequency on it gradually diminishes to zero when the number of cycles is large enough, and the dynamic strengths at different frequencies tend to the same limiting minimum dynamic strength. The test results demonstrate that the reasons for the frequency effect on the undrained soil behaviors are beth the creep effect induced by the loading rate and the decrease of sample effective confining pressure caused by the accumulated pore water pressure.  相似文献   

不同年度收存的褶皱臂尾轮虫休眠卵的孵化及滞育胚胎“激活”效果的研究   总被引：3，自引：0，他引：3  

周利  相建海  郑严 《海洋与湖沼》2002,33(6):648-656

比较了 1 985— 1 998年间由同一褶皱臂尾轮虫 (Brachionusplicatilis)种群在实验室内历年产生并收存的休眠卵的孵化效果 ,并初步探讨了胚胎“激活”处理对孵化的影响。结果表明 ,休眠卵的收存年度或时间对其在一定孵育期内的总孵化率 (THR)和日孵化率 (DHR)有极显著影响 (x2 检验 ,p<0 .0 0 1 ) ,但THR和DHR与储存时间间均无显著的相关性 ,而是呈极大波动。同时发现“激活”作用具有促使孵化高峰提前到来、增强孵化同步性的双重功效 ,从而可明显缩短孵育时间 ,提高孵化速率。但“激活”前后多数卵样的总孵化率无显著变化 (p >0 .0 5 )。详细讨论了可能导致孵化率波动的多种因素 ,例如遗传变异、培养历史、储存及孵化的环境条件等。  相似文献   

An optimized method for automated analysis of algal pigments by HPLC   总被引：3，自引：0，他引：3  

M.A. van Leeuwe  L.A. Villerius  J. Roggeveld  R.J.W. Visser  J. Stefels 《Marine Chemistry》2006,102(3-4):267-275

A recent development in algal pigment analysis by high-performance liquid chromatography (HPLC) is the application of automation. An optimization of a complete sampling and analysis protocol applied specifically in automation has not yet been performed. In this paper we show that automation can only be successful if the various methodological aspects of the sampling and analysis protocol are considered in coherence. We introduce an optimized protocol that involves freeze-drying of the sample, subsequent extraction in 90% acetone and the application of water-packing during analysis. The method was evaluated on both natural plankton populations and a broad spectrum of microalgal cultures: Thalassiosira weisflogii (Bacillariophyceae), Emiliania huxleyi (Prymnesiophyceae), Phaeocystis globosa and Phaeocystis antarctica (Prymnesiophyceae) and Pyramimonas sp. (Prasinophyceae). Whereas pigment extracts were unstable in methanol, with recorded chlorophyll a losses from 10% to 60% per day, pigment degradation rates in acetone were generally less than 1% over 18 h storage in the autosampler (4 °C). In addition, it was found that the extraction efficiency of acetone significantly increased upon freeze-drying prior to extraction. Increases as high as 50–60% were measured in P. antarctica. The application of water-packing of the sample during injection resulted in improved peak shape and peak separation, without diluting the pigment concentrations. Automation is especially beneficial for application in the field, when mixed algal assemblages and low biomass put a high demand on the sensitivity as well as reproducibility of the method.  相似文献   

钢筋混凝土梁结构断裂损伤诊断方法     

周尚志  王丽华刘瑛 《海洋工程》2005,23(4):47-51

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   

1999年渤海浮游植物生物量的数值模拟   总被引：6，自引：1，他引：6  

高会旺  王强 《中国海洋大学学报(自然科学版)》2004,34(5):867-873

以浮游植物量、浮游动物量、营养盐浓度 (包括无机氮和无机磷 )以及碎屑量为生态变量 ,在HAMSOM水动力学模式的基础上构建了 1个三维浮游生态动力学NPZD模型。采用此模型研究了渤海 1999年浮游植物量和初级生产力的变化情况 ,模拟结果与实测基本相符。模拟结果表明 :1999年渤海浮游植物量的变化大致呈双峰分布 ,春季水华出现在4,5月份 ,秋季水华出现在 9,10月份 ;受透明度和局地水深的影响 ,渤海湾和辽东湾北部浮游植物量的年变化呈夏季大、冬季小的单峰分布。 1999年渤海不同海区初级生产力的变化特征是 :除莱州湾一年中有春、夏 2个峰值外 ,其它 3个海区都是夏季高、冬季低的单峰分布 ;1999年整个渤海年平均的初级生产力为 2 5 7mgC/m2 /d。  相似文献   

近海环境地球化学调查研究历史与现状   总被引：1，自引：0，他引：1  

叶思源  周永青  刘兆茂  刘建霞 《海洋地质与第四纪地质》2003,23(4):121-126

近海环境地球化学的研究是一支新兴的发展中的边缘性分支学科，由于环境问题的日益突出，该学科发展较为迅速。通过回顾我国近海环境地球化学调查的历史和综述当今国外该学科的研究现状，概括了该学科的主要进展，并指出存在的问题和今后的发展方向。  相似文献   

Neural Network-Based Active Control for Offshore Platforms     

周亚军  赵德有 《中国海洋工程》2003,17(3)

1 .IntroductionWiththedevelopmentofoceantechnology ,moreandmoreextremelylargeandlongflexibleoff shoreplatformsusedforoilexplorationanddrillingoperationarebuiltinhostileoceanenvironments .Ingeneral,thiskindofplatformsisanonlineardistributedparametersystemanditsnaturalfrequencyfallsclosertothedominantwavefrequencieswiththeincreaseofwaterdepth .Besides ,itsstructureisverycomplexandtheexternalwaveforceontheplatformisuncertain .Thus ,theseplatformsarepronetoexcessivewave inducedoscillationsunderbot…  相似文献