Long-Period Distribution of Wave Heights and Its Application

This paper reveals that the long-period statistic distribution of the characteristic heights of deep-water waves assumes the lognormal distribution. Thereafter, the largest wave-height which may occur in the service life of coastal structures is derived in this paper.     

罗氏沼虾育苗用水中Mg2+与Ca2+含量及Mg2+/Ca2+对出苗率的影响

１９９１年３－６月和１９９２年３－６月在南汇县东海水产养殖公司对罗氏沼虾育苗用水调配原则与不同基础水的调配方法进行试验研究。结果表明，育苗用水中Ｍｇ＾２＋与Ｃａ＾２＋含量及Ｍｇ＾２＋／Ｃａ＾２＋必须达到一定的范围，这是调配的基本原则。以鱼塘水作基础水时，需添加６种化学药品，其中Ｍｇ＾２＋与Ｃａ＾２＋含量可适范围分别为３００．０－４４０．０ｍｇ／Ｌ与１７０．０－２４４．０ｍｇ／Ｌ，Ｍｇ＾２＋／Ｃａ＾     

The second order spectrum of two-dimensional random waves

Ｔｈｅｓｅｃｏｎｄｏｒｄｅｒｓｐｅｃｔｒｕｍｏｆｔｗｏ－ｄｉｍｅｎｓｉｏｎａｌｒａｎｄｏｍｗａｖｅｓ￥ＤｉｎｇＰｉｎｇｘｉｎｇ；ＳｕｎＦｕａｎｄＹｕＺｈｏｕｗｅｎ（ＲｅｃｅｉｖｅｄＪａｎｕａｒｙ１５，１９９３；ａｃｃｅｐｔｅｄＭａｙ３１，１９９３）Ａ...     

Full-range nonlinear analysis of fatigue behaviors of reinforced concrete structures by finite element method

Ｆｕｌｌ－ｒａｎｇｅｎｏｎｌｉｎｅａｒａｎａｌｙｓｉｓｏｆｆａｔｉｇｕｅｂｅｈａｖｉｏｒｓｏｆｒｅｉｎｆｏｒｃｅｄｃｏｎｃｒｅｔｅｓｔｒｕｃｔｕｒｅｓｂｙｆｉｎｉｔｅｅｌｅｍｅｎｔｍｅｔｈｏｄ￥ＳｏｎｇＹｕｐｕ；ＺｈａｏＳｈｕｎｂｏ；ＷａｎｇＲｕｉｍ...     

The elemination of re-reflected waves by a porous medium of finite thickness

The elimination of re-reflected waves in a wave channel by installing a porous medium in front of the wavemaker is investigated. The thickness of the porous wall required to eliminate the re-reflected waves is shown to be related to th porosity, friction coefficient, and wave period, as well as to both the positions of the porous medium and the test structure. However, this study indicates that the goal of eliminating re-reflected waves can be achieved by simply varying the thickness of the porous medium according to the wave period, with all the other factors arbitrarily selected.Assuming that the oscillation amplitude of the wavemaker board is constant, the primitive wave amplitude, before reaching the porous medium, becomes smaller as the wave period is increased. In addition, the study found that the required thickness of the porous medium for eliminating the re-reflected wave becomes larger as the wave period is increased. This results in a trend which further reduces the wave amplitude after the wave passes through the porous medium. In consequence, the oscillation amplitude of a wavemaker board has to be adjusted in a larger scale if the wave period is to be increased.     

紫菜一新种——福建紫菜的研究

于1978年1月在福建莆田县乐屿岛采集紫菜属标本,进行分类研究。经鉴定表明,其中一种系新种,定名为福建紫菜Porphyra fujianensis sp.nov.。分类方法见曾呈奎等(1962)。本种特征为:藻体长带状,边缘细胞为刺缘型;雌雄同体,精子囊器与果孢子囊成条状或块状,混生或呈镶嵌式分布,形似条斑紫菜;精子囊器分裂式为(?)A_4B_4C_4,果孢子囊分裂式为♀A_2B_4c_2;藻体产生单孢子,进行无性繁殖。模式标本存放于厦门水产学院养殖系。     

海洋沉积物声速与物理参数的关系

海洋沉积声速与物理性质密切相关，特别是含水量Ｗ和孔隙度Ｎ，它们在建立回归议程和预报沉积物性质中有所贡献。中国东，南海沿海沉积物的资料和数据表明：声速和声速比可以用来预报沉积物性质。     

Effects of polynuclear aromatic hydrocarbons on lysosomal membranes in molluscs

Lysosomal sequestration of polynuclear aromatic hydrocarbons (PNAHs), a major class of environmental contaminant, is a well-established phenomenon;¹ considerably less is known about their pathological effects on lysosomes. Marine molluscs contain a number of lysosome-rich tissues and PNAHs are known to induce deleterious alterations in lysosomal structure and latency of lysosomal enzymes.² The latter are presumed to involve destabilisation of the lysosomal membrane, resulting in increased permeability and reduced enzyme latency. If lysosomal injury involves derangement of membrane-lipid structure due to the interaction of PNAHs then it would be expected that membrane damage would be closely linked to the structural characteristics of the intruding molecule. Our results show that the effects of the isomeric PNAHs phenanthrene and anthracene on digestive cell lysosomal stability were markedly different in the marine mussel (Mytilus edulis) over the same range of tissue concentrations. Lysosomal membrane stability was determined using a cytochemical test for enzyme latency.³     

The statistics of second order wave forces

A starting point in the statistical analysis of the slow drift motions of moored offshore structures is the determination of the statistical distribution of the second order exciting forces. In the past^2,6 an exponential probability density function has been used, this being the limiting case as the incident seastate becomes infinitely narrow banded. In the present note the second order force distribution is found for a general seastate and a significant deviation from an exponential distribution is found for those seastates which are likely to occur in practice. The statistical theory is based on a heuristic approximation to the second order force, which is shown to be consistent with a frequently used frequency domain approximation which has been suggested by Newman.⁸ Although Roberts² has shown that for very lightly damped systems the response statistics are independent of those of the exciting force, the present results may have a significant effect on the response statistics for higher levels of damping.     

The Ectoparasitic Gastropod Boonea (= Odostomia) impressa: Population Ecology and the Influence of Parasitism on Oyster Growth Rates

Abstract. Boonea (= Odostomia) impressa is a common ectoparasite of oysters. In the laboratory, small oysters (Crassostrea virginica) parasitized by natural densities of B. impressa produced 75 % less new shell than unparasitized oysters. Shell deposition rates of previously parasitized oysters increased significantly after all B. impressa were removed. Thus, the decrease in growth rate, although significant, apparently was not permanent. B. impressa preferentially parasitized small, living oysters (≤2.5cm) in the field, even though a higher percentage of large, living oysters (>2.5cm) was available. The snails maintained an aggregated distribution on the oyster reef. The number of B. impressa per oyster clump was positively correlated with the number of living oysters per clump, however some clumps with few or no living oysters had many B. impressa. Thus, food availability only partially explained the pattern of distribution. B. impressa was very mobile. About 50 % of the population moved in one week. Reproduction occurred throughout the year with a peak period in May. Recruitment was greatest in July, however new recruits were observed throughout the year. The reduction in growth rate of parasitized oysters, the snaiľs propensity towards parasitizing small oysters and the snail's tendency to be contagiously distributed suggests that B. impressa potentially exerts a significant influence on the population structure and health of oyster populations.