Semi-Probabilistic Evaluation of System Redundancy for Existing Offshore Structures

In this paper, a new definition of structure system redundancy is proposed in view of the various measures for structure redundancy. By introducing the terms of structure system failure at the mechanism level and equivalent reliability index, the safety for existing offshore platforms can be evaluated by the semi-probabilistic method presented in this paper. Some numerical examples are given and satisfactory results have been obtained.     

Behavior of Pile Groups under Lateral Load

Based on investigation and model tests, and in combination with the research work on group effect for pile groups under lateral loads relating to the code of fixed offshore platforms, a series of studies have been performed on the behavior and failure mechanism of laterally loaded pile groups, critical pile spacing inducing group effect, lateral bearing capacity of pile groups and its main influence factors, the stress-strain relationship for single piles and pile groups and so on. Some new laws about non-uniformity of load distribution in the longitudinal direction of pile groups and load-deflection (p - y) curves for pile groups have been discovered, and an empirical formula is presented in order to remedy the defect of current calculating methods at home and abroad. These results can be used for reference in the design of pile foundation under lateral loads.     

辽宁菊花岛海域沉积物中某些化学要素分布特征研究

菊花岛周围海域38个站表层沉积物的铁、锰、铝、钛、磷、有机质、氮、铜、锌、铅、镉、镍和汞等化学要素含量的Q型因子分析计算表明,本区可划分为三个化学元素沉积区:1.海流悬浮沉积区;2.近岸波浪作用区;3.波浪海流作用区。柱状沉积物中铁等化学元素的迁移、富集受氧化——还原界面的控制。     

黄河口及其邻近海域营养盐分布特征

1985年5、8月中法联合调查黄河口海域的营养盐,其样品采用常规的分光光度法测定。营养盐的分布总趋势是河口附近浓度高,外海浓度低,河口与外海浓度之比达数百倍。在河口及其邻近海域营养盐的分布梯度与盐度的分布一致。在河口控制营养盐含量的主要因素是河水和海水的混合过程。在119°30′～50′E,37°25′～38°5′N,PO_4—P,SiO_3—Si出现低值区。在此范围附近恰恰浮游植物的总量比较高。对8月份的02站进行了25h的连续观测,其结果是底层营养盐与盐度有良好的负相关性,而表层的相关性较差 黄河具有很高的氮磷比值,这很可能是农业上用氮肥量增多引起的。     

秦山核电站邻近水域浮游植物的生态研究

本文分析了秦山核电站邻近水域生态零点调查四个航次的浮游植物样品,结果表明:调查区浮游植物的种数和细胞密度在时间尺度上均存在明显的季节变化趋势:夏大于秋大于春大于冬,并且与环境因子的变化密切相关,其中最主要的影响因子是温度、盐度和径流,而影响日变化的环境因子主要是潮汐。     

An analysis on El Nino processes during 1949-1987

-In this paper, the outset, evolution and intensity of El Nino were analyzed. Different features were found in each El Nino process. The El Nino of 1986 was also analyzed and outlined.     

西沙群岛的海草

海草在世界各海域已知有12个属,其中8个属在我国有分布。在从五十年代后期开始的西沙群岛动、植物区系调查中,先后采到海龟草 Thalassia hemprichii ( Ehrenb.) Aschers.、喜盐草 Halophila ovalis (R.Br.) Hook.和无横脉喜盐草 H. beccarii Aschers.等三种海草,分隶于二属。 海草是一个热带性较强的类群,在已知的12个属中,有7属以热带为分布中心。分布在我国沿海的8属海草中,也有6属是热带性的(包括西沙群岛的2属3种),其中海龟草是纯热带种类,而喜盐草和无横脉喜盐草是热带一亚热带类型。 在我国,有关海草的研究甚少,本文首次报道西沙群岛海草。海龟草、喜盐草及无横脉喜盐草均为我国新记录。     

东亚和东南亚第四系时间界面的建议

在东亚和东南亚第四系对比中,有关的几条界限,本文建议如后。采用Globorotalia truncatulinoides的初现位作为本区海相第四系的下界,其位置大致在古地磁Olduvai亚时的下界,时间约为距今1.9Ma。在南中国海、东海及沿岸地区,发现了以G.truncatulinoides的初现位为代表的一系列有意义的生物事件,如Pulleniatina finalis的初现位,Globigerinoides obliquus和Globoquadrina altispira的灭绝位,以及Globorotalia menardii和Pulleniatina obliquloculata壳体旋向的变化。此界限在东亚和东南亚也是相当稳定的。在陆相地层中,以泥河湾组为代表,狭义的泥河湾动物群(相当于晚维拉方动物群)所在地层的底界,其古地磁位置为Olduvai亚时的底界。以此作为陆相第四系的下界,与上述海相第四系底界一致。 以古地磁布容/松山界线作为中更新世和早更新世的界限,其年代为0.73MaB.P.。中国中更新世的标准地层周口店组,其底界恰为布容/松山的转换面,北京猿人的年代为0.60—0.23MaB.P.。在洛川黄土剖面上,布容/松山界线为古土壤S_7的底界。雷琼地区中更新统下部的北海组的底界也是布容/松山界线,所产的玻璃陨石的裂变径迹年龄为0.687—0.733MaB.P.。在黄海,布容/松山界线是第Ⅶ海侵层的顶界。通过岩石地层标志,以及动物群、古人     

多管藻内生真菌Chaetomium globosum.苯甲醛类次生代谢成分研究

从采自青岛近海的红藻多管藻(Polysiphonia urceolata)中分离到一株毛壳霉属真菌球毛壳菌(Chaetomium globosum.),对其发酵代谢产物的化学成分进行了研究。采用溶剂提取、分配,硅胶柱层析、葡聚糖凝胶柱层析以及制备薄层层析等技术已分离获得6个单体化合物,通过一维、二维超导核磁共振技术、质谱技术等鉴定了其中4个化合物的结构,均为苯甲醛类衍生物,分别为2-(1-庚烯基)-3、6-二羟基-5-(3-甲基-2-丁烯基)苯甲醛(Ⅰ)、2-庚基-3、6-二羟基-5-(3-甲基-2-丁烯基)苯甲醛(Ⅱ)、2-(3、5-庚二烯基)-3、6-二羟基-5-(3-甲基-2-丁烯基)苯甲醛(Ⅲ)、2-(1、3、5-庚三烯基)-3、6-二羟基-5-(3-甲基-2-丁烯基)苯甲醛(Ⅳ)。     

A climatology of mesoscale model simulated low-level wind jets over Cook Inlet and Shelikof Strait, Alaska

Weather in the North Gulf of Alaska is characterized by a high frequency of deep synoptic-scale low-pressure systems, especially during the cold season. The strong pressure gradients of these storms interact with the extremely rugged terrain of the coastal mountains to produce a variety of channeled flows. These surface wind regimes are not well documented in the scientific community, due to the paucity of observations. Modeling of these phenomena in regions of complex terrain is of great interest to those working with hydrodynamic, wave, and pollutant transport models in coastal and shelf areas. Such models, when coupled with ocean and coastal-ecology counterparts, give a broad view of the role surface winds play in shaping local coastal marine ecosystem in this region. This paper presents a climatology of simulated low-level wind jets over the domain of Cook Inlet and Shelikof Strait along Alaska's south-central coast. Daily simulations using the RAMS model were conducted in a 36-h forecast mode for the cold-season period 10/1/03 to 3/31/04. Systematic analysis of the resulting simulated low-level wind field makes it possible to characterize these jets and gap flows in spatial and temporal detail. The comparison between the RAMS winds and the Synthetic Aperture Radar (SAR)-derived winds when available verifies the existence of these wind jets and the capability of the model to simulate these cases. Clearly, the results of a study in this region depend on the fidelity of the model at these scales (O[5 km]). The SAR comparisons attempt to help establish this. From the 6 months of simulations over Cook Inlet and Shelikof Strait, the low-level wind jets are classified into 10 different regimes by location and orientation. These regimes are categorized into four more general groups: cross-channel westerly, easterly, and up and down Inlet flows. The nature of a particular regime is largely a function of pressure gradient orientation and local topography. Jets in the same group have a similar occurrence distribution with time. Some form of jet occurred in the study region almost daily each month of the period, with December 2003 having the highest frequency of wind jets.