Analytically derived wind-wave directional spectrum part 1. Derivation of the spectrum     

Sheng-Chang Wen  Pei-Fang Guo  Da-Cuo Zhang 《Journal of Oceanography》1993,49(2):131-147

In contrast with the usual method to obtain the wind-wave directional spectrum by multiplying the frequency spectrum with an empirical directional function, the authors attempt to derive analytically the directional spectrum by adopting proper spectral form and using effective parameters, namely, the zero order momentm ₀ of the wind-wave frequency spectrumS(), its peak frequency ₀ and the so-called peakness factorP=₀ S(₀)/m ₀, where is angular frequency. The directional spectrum is given in a form of frequency spectrum for each direction. The spectral directionality depends on, in addition to frequency, the wind-wave growth status, for the peakness factorP as introduced by the authors previously is a measure of the wave development stage. The salient features of the directional spectrum, comparison with existing formulas and the verification of the spectrum by observational data are to be given in the Part 2 of the paper.Project supported by the National Natural Science Foundation of China.  相似文献   

东海围垦滩地强夯作用下孔隙水压力响应试验研究     

霍素霞  刘涛  高振会 《海岸工程》2006,25(1):41-46

围垦滩地饱和粉土地基属于软土地基的一种,其含水量高,渗透性差,强夯加固作用使地基土中的孔隙水压力瞬时升高,且短时间内得不到消散,容易出现“橡皮土”。通过现场试验研究了饱和粉土地基在强夯作用下孔隙水压力的响应规律,确定了两遍强夯之间的间歇时间和强夯的影响深度,以便优化强夯参数,正确指导强夯施工。  相似文献   

A Numerical Study on the Structure and Dynamics of Turbulence in Oscillatory Bottom Layer Flow over A Flat or Rippled Bed     

白玉川  吴朝安黄涛 《中国海洋工程》2006,20(1):45-60

1 .IntroductionUnder the influence of surface waves ,sandripples often appear on beaches . Whenthe amplitudeof water oscillationis sufficientlylarge ,vortices are formed onthe lee of every sand ripple crest . A-mongthese vortices ,the most important are t…  相似文献   

扇贝提取物对实验性高脂血症大鼠血脂及脂质过氧化的影响     

毛文君  李翊  李八方 《海洋科学》2002,26(4):69-71

硒与心血管的结构、功能及其疾病的发生关系密切。世界卫生组织和国际原子能协会已把硒列为与冠心病发病有关的５种元素之一而加以研究。近年来 ,人们逐渐认识到脂质过氧化机理在动脉粥样硬化发生发展中的作用 ,体内血脂代谢异常及氧化损伤是动脉粥样硬化发生发展的重要原因。硒作为自由基清除剂在一定程度上 ,有调节血脂代谢及抗氧化的作用。饮食摄入一定量的硒和体内维持一定水平的硒 ,对防止高脂血症具有积极意义。扇贝提取物是以扇贝为原料提取制备的富含微量元素硒及多种微量元素、维生素和蛋白质等生理活性物质的富硒提取物。本研究利…  相似文献   

Theoretical wind wave frequency spectra in deep water——Ⅰ. Form of spectrum   总被引：1，自引：0，他引：1  

Wen Shengchang 《海洋学报(英文版)》1988,7(1):1-16

In this part ot the paper theoretical wind-wave spectra nave been derived oy (I) expressing the spectrum in series composed of exponential terms; (2) assuming that the spectrum satisfies a high order linear ordinary differential equation; (3) introducing proper parameters in the spectrum; and (4) making use of some known charateristics of wind-wave spectrum, for instance, the law governing the equilibrium range. The spectrum obtained contains the zero order moment of the spectrum m0, the peak frequency ω0 and the ratio R =ω/ω0 (ω being the mean zero-crossing frequency) as parameters. The shape of the nondimensional spectrum S(ω) = ω0S(ω)/m0(ω=ω/ω0) changes with R and theoretically reduces to a Dirac delta function δ(ω-1) when R = 1. A spectrum of simplified form is given for practical uses, in which R is replaced by a peakness factor P=S(1).  相似文献   

Dynamics of subtidal flow in the Taiwan Strait   总被引：7，自引：0，他引：7  

Wen -Ssn Chuang 《Journal of Oceanography》1985,41(2):65-72

Two current meter moorings were deployed in the Taiwan Strait from 3 April to 5 May 1983. The data indicate that the subtidal flow in this rather wide strait can be separated into two parts: the mean flow and wind-driven flow, which make about equal contributions to the overall flow. The mean flow is probably originates from branching of the Kuroshio through Bashi Channel. The magnitude of the current is nearly 30 cm sec^–1 flowing northward, and the corresponding along-strait sea surface slope is on the order of 10^–7. The residual flow is a local wind-driven flow, and reaches a frictionally balanced state in about 4 hr. Assuming a linear drag law for the bottom stress, a hindcast scheme is constructed and the results compare well with the observations.  相似文献   

伶仃洋L＿2和L＿（16）孔第四纪有孔虫群与孢粉化石带特征及其地质意义   总被引：5，自引：0，他引：5  

陈木宏  赵焕庭  温孝胜  张乔民  宋朝景 《海洋地质与第四纪地质》1994,(1)

本文所依据的分析样品是取自珠江最大的一个河口湾伶仃洋中部的水下钻孔岩芯，其底部到达花岗岩基底。通过对第四纪有孔虫群与孢粉化石带特征的分析，阐明在相同的钻孔岩芯中，有孔虫分布变化所反映的古沉积环境特征与孢粉分析的古气候特征较为吻合，并与相应的沉积相对应，结合￣（１４）Ｃ和￣（２３０）Ｔｈ／￣（２３２）Ｔｈ比值法测年数据，从而较好地重塑本区晚更新世中期以来的地质历史。  相似文献   

浅海内波垂直模式方程的一种解析解     

胡涛  高天赋 《海洋学报》2007,29(4):148-151

给出了一些海区实测浮力频率剖面的数学模型.利用超几何函数对内波垂直模式方程进行了解析求解,得到内波模式方程的解析解和频散方程.利用得到的解析解给出了一种理想条件下内波前三阶简正模式的结构.  相似文献   

南黄海鳀鱼(Engraulis japonicus)产卵场小型桡足类的数量分布     

左涛  王荣  高尚武  王克 《海洋与湖沼》2006,37(4):330-336

2000—2002年6月在黄海西南侧、山东半岛南部鳀鱼产卵场专项调查中,由底至表垂直拖网获得浮游生物中网(网孔径160μm)浮游动物样品,作者就该产卵场内四种主要小型桡足类(体长<1mm)双刺纺锤水蚤、小拟哲水蚤、拟长腹剑水蚤和近缘大眼剑水蚤的数量分布进行分析。在连续三年的6月,测区内均以小拟哲水蚤和拟长腹剑水蚤数量最多。四种小型桡足类的数量空间分布虽有一定的种间、年间差异,但总体上来说,四种小型桡足类的密集中心大多分布于山东半岛沿岸或近苏北浅滩沿岸水域。相关性分析表明,双刺纺锤水蚤和近缘大眼剑水蚤与底层水温呈正相关,与盐度呈负相关,拟长腹剑水蚤与底层水温呈负相关,与盐度呈正相关。小拟哲水蚤与温度的相关性较大。双刺纺锤水蚤和小拟哲水蚤与鳀鱼仔、稚鱼的数量分布有着较为显著的正相关。  相似文献   

健康型牛蛙饲料养殖牛蛙的试验     

陈晓凤  王玮玮  江涛  苏永裕  刘章锦 《台湾海峡》2001,20(Z1):107-111

本研究采用5种中草药添加剂配方的膨化饲料进行了为期36d的牛蛙养殖对比试验.结果表明，饲料中添加有中草药制剂的日摄食量明显大于对照组，日增重显著比对照组的高.而且大大加快了生长速度，缩短养殖周期，同时减少了染病机率，牛蛙体色鲜艳、光泽度极佳.  相似文献