Frequency-selective attenuation of sound propagation and reverberation in shallow water

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Effects of an Artificial Breakwater on the Distributions of Planktonic Microbial Communities

The summer distributions of planktonic microbial communities (heterotrophic and phtosynthetic bacteria, phtosynthetic and heterotrophic nanoflagellates, ciliate plankton, and microphytoplankton) were compared between inner and outer areas of Lake Sihwa, divided by an artificial breakwater, located on the western coast of Korea, in September 2003. The semienclosed, inner area was characterized by hyposaline surface water (<17 psu), and by low concentrations of dissolved oxygen (avg. 0.4 mg L¹) and high concentrations of inorganic nutrients (nitrogenous nutrients >36 μM, phosphate <4 μM) in the bottom layer. Higher densities of heterotrophic bacteria and nanoflagellates also occurred in the inner area than did in the outer area, while microphytoplankton (mainly diatoms) occurred abundantly in the outer area. A tiny tintinnid ciliate, Tintinnopsis nana, bloomed into more than 10⁶ cells L¹ at the surface layer of the inner area, while its abundance was much lower (10³-10⁴ cells L¹) in the outer area of the breakwater. Ciliate abundance was highly correlated with heterotrophic bacteria (r = 0.886, p < 0.001) and heterotrophic flagellates (r = 0.962, p < 0.001), indicating that rich food availability may have led to theT. nana bloom. These results suggest that the breakwater causes the eutrophic environment in artificial lakes with limited flushing of enriched water and develops into abundant bacteria, nanoflagellates, and ciliates.     

Strength Analysis of Turret Mooring Productive/Storage Tanker

The longitudinal strength of turret mooring productive/storage tanker is studied.A numeri-cal example has been implemented according to the method presented in this paper to give practical il-lustration.From the results of the numerical example,it is concluded that the turret hole located near theforward of the amidships has small effect on the longitudinal strength of the ship hull.As for design ex-treme value of wave bending moment of storage tanker,statistic method is a more reasonablemethodology,especially with the consideration of the servere environmental conditions.The primary esti-mation of design section modulus of turret storage tanker can be determined by this design bending mo-ment.     

北黄海盆地区域地质特征

北黄海盆地位于黄海的北部，由于勘探程度低，研究投入少，使得它成为我国迄今为止尚未发现油气的惟一海区。随着我国在南黄海盆地和朝鲜在北黄海盆地东部发现油气，如何实现北黄海盆地油气突破，成为我们研究的焦点。结合该区现有资料和前人研究成果，对北黄海盆地的地球物理场和地质构造特征进行了全面的论述，并在此基础上，对该区油气资源远景作了初步评价。     

四川椎实螺属一新种(肺螺亚纲:基眼目,椎实螺科)

作者1987年于四川省乐山市大渡河尾段发现椎实螺属一新种,现命名为乐山椎实螺(Lymnaea leshanensis sp.nov.)。该种与日本琵琶湖产的 Lymnaea onychia 相似,但贝壳的形态、齿式、齿形、两性生殖系统的诸器官、外套膜的色带、个体大小、生活环境和动物区系均有所不同。前者属东洋区系,后者属古北区系。     

沉降监测多项式回归分析与神经网络预测

使用多项式和切比雪夫(Tchebyshev)多项式分别对沉降监测数据进行回归分析以预测未来沉降值,其中切比雪夫多项式的外推效果较好;应用前向BP神经网络对两种不同的单因子输入模式进行非线性函数逼近,并进行了不同采样步长的比较,实例表明将时间点作为网络的输入对沉降进行预测效果较好。     

中国鳚亚目鱼类地理分布和区系特征

鳚亚目鱼类是鲈形目中较大的一个亚目，现知全世界有127属，700余种(Nelson，1994)。目前还不断有新种发现，多数为海洋鱼类，世界性分布。 鳚亚目鱼类大多体型较小，对它们的研究也少。随着科学技术的发展和研究方法的不断完善，人们对这一类群的认识也愈来愈深入，其种类、区系与动物地理学等方面的特点正逐渐为研究者所揭示。其中有些种类由于在海洋生态学、环境生物学和渔业生产上具有重要意义而吸引着许多鱼类学家和生态学家的注意和对其进行研究(Kotrschal，1992；Springer，1993；Stepien，1993)。 印度-西太平洋是鳚亚目鱼类种类最多的海区之一，中国及周边国家和地区在此领域已有一定的研究基础。日本学者Masuda等(1984)总结了日本沿岸鳚亚目鱼类有86属212种，菲律宾已知有36属80余种(Herre，1953)。中国是世界上海岸线最长的国家之一，适合于鳚亚目鱼类栖息的生境相当广泛，种类也相当丰富。作者根据目前已掌握的标本和文献资料，经初步分析得出中国海区现有鳚亚目鱼类33属78种。     

水样及生物体内微量锌、锰、硒的极谱催化波同时测定

本文提出了在酒石酸盐-乙二胺-高氯酸-亚硫酸钠-高碘酸钾-EDTA体系中同时测定微量锌、锰、硒的极谱催化波，波峰敏锐，波形稳定。Zn2 浓度在0．4～40μg／dm3，Mn2 浓度在1．6～80μg／dm3，Se（Ⅳ）浓度在0．02～3．0μg／dm3范围内浓度与峰电流呈线性关系。取天然水样平行12份测定，变异系数在10％以内。     

渤海、黄海强温跃层数值预报模式

文中对前人关于水温垂直结构计算、模拟和预报研究成果进行了评价，并在此基础上建立了考虑海面吸收辐射和透射辐射、地形、风、海流、界面摩擦及其引起的混合作用的强温跃层三维数值预报模式。该模式运行的驱动量仅为风和气温场资料，因而具有较好的实用性；此外，从试报的结果看，效果是令人满意的。     

波浪底摩擦力对重砂富集的影响——以鲁南近岸区为例

根据浅水波浪的底摩擦效应，对鲁南灵山湾和臼－岚山镇近岸区进行了波浪的海底摩擦力计算。波浪的海底摩擦力等值图与已知滨海锆石砂矿资料对比表明，底摩擦力大于０．１８Ｎ／ｍ＾２的动力分选区有利于重矿物砂富集。据此，进一步预测了鲁南近岸带的砂矿富集区。