长期非平稳荷载调谐质量减振阻尼器优化设计

研究外荷载为长期非平稳随机过程。考虑长期荷载的特性 ,采用 1个概率谱密度函数来反映长期非平稳随机荷载及其特征 ;概率谱密度函数是基于大量的一般谱密度函数的统计特性获得。以延长结构的抗疲劳使用寿命为目标函数 ,提出了调谐质量减振阻尼器的优化设计方法 ,这在实际工程中有着极为广阔的应用前景。本文旨在从理论上发展长期非平稳随机荷载作用下调谐质量减振阻尼器的优化设计方法 ;文中采用长期波浪实测数据 ,给出了 1个数值算例说明整个设计过程。     

关于海域面积精确计算的若干问题探讨

海域面积精确计算是实现海洋功能区划的基础和关键之一。本文通过对江苏省海洋功能区划工作中误差的分析 ,并针对其产生原因 ,在地图投影的选择和坐标的变换、扫描精度的控制、配准精度的控制、图象的数字化和图形编辑等方面 ,提出了相应的优化处理方法 ,提高了海域面积计算的精度 ,将其中误差控制在估计值范围内 ,从而在实际工作中有一定的应用价值。     

渤海南部表层沉积的相特征

通过海上调查及实验室分析,查明渤海南部表层沉积物在结构类型、矿物组合、生物组分及沉积构造等相特征方面具有明显的分区性。渤海南部存在五种沉积相:黄河水下三角洲相、陆架盆地相、海湾相、潮流浅滩相及古滨岸相。黄河水下三角洲相从河口延至水深15—20米处,沉积速率很高,沉积物富含碎屑云母及CaCo_3。陆架盆地相的沉积为粉砂质粘土,具有生物扰动构造。     

Investigation of the hydrate reservoir production under different depressurization modes

Abstract

Large reserves of natural gas hydrates exist, and the depressurization method has the greatest potential for gas hydrate reservoir recovery. Currently, the most commonly adopted depressurization simulation method is a constant bottom-hole pressure production scheme. This study proposes a new depressurization mode with decreasing bottom-hole pressure. The production characteristic was numerically investigated using this method. The results show the following: (1) As the depressurization exponent (n) decreases, the development effect improves, and production indexes including cumulative gas production/dissociation and gas-water ratio increase. However, the reservoir energy consumption is higher and the hydrate reformation is more severe. (2) Compared to the proposed depressurization mode, the hydrate production index of the constant bottom-hole pressure production (n?=?0) is better. However, the hydrate reservoir energy consumption is higher and the hydrate reformation is more severe using constant bottom-hole pressure production. (3) To achieve a balance between production and reservoir energy consumption during depressurization production, the bottom-hole pressure should be controlled by selecting a suitable depressurization exponent between n_min and n_max, which can be determined through numerical simulations.     

红海湾水域溶解氧、pH值、盐度和营养盐分布特征及相互关系研究

通过１９９８年６月对广东省红海湾海水养殖水域环境因子的调查,阐述了海水中溶解氧、盐度、ｐＨ值和营养盐的分布特征及其变化规律,并讨论了它们之间的相互关系,结果表明,溶解氧及海水ｐＨ值随温度由北（除１５￣１７号站）向南（除６号站）增高而增高。同时证实了光合作用是导致溶解氧含量和ｐＨ值增高的主要原因。而营养盐与盐度呈密度的负相关,浮游植物总量随营养盐由北向南降低而明显增高。     

烟台市污水处理深海排放工程设计方案研究与选择

沿海城市污水处理深海排放工程在我国起步较晚，烟台市污水处理深海排放工程我国目前规模最大的同类工程，且已进入施工阶段，本文详细阐述了该工程及水工设计方案，在我国城市污水２深海排放工程领域作了积极有益的探索。     

黄海溶解氧垂直分布最大值的成因

本文对黄海溶解氧垂直分布中最大值的成因进行了探讨．认为：浮游植物春花期光合作用产生的大量氧，是溶解氧垂直分布最大值得以在春季（5月）形成的基础；而良好的温、密跃层的存在是氧最大值得以形成的必要条件，夏季叶绿素最大值层中较强的光合作用，是氧最大值在夏季得以维持甚至增强的主要原因．提出：黄海春、夏季溶解氧垂直分布中的最大值并非主要由冬季保持而来．     

浙北潮下带（0——5m）大型底栖生物生态

首次对浙北潮下带（０～－５ｍ）水域生物学调查表明：共鉴定底栖生物２２２种，隶属１０３科１７０属；该区生物数量较高（生物量为８０．８８ｇ／ｍ２，栖息密度为６５５个／ｍ２），以软体动物为主要类群；群落结构可划分为五个类型。底栖生物的分布与水域盐度、温度、底质性质、海湾屏蔽度有密切的关系。     

Improved form of wind wave frequency spectrum

The lower frequency part of the theoretical wind wave spectrum proposed by the authors (Wen et al. , 1988a, b,c) has been improved and the form of spectrum is appreciably simplified. In addition to the field data collected in the Bohai Sea region and used in the previous papers, those obtained in the Huanghai Sea, the East China Sea and the South China Sea have been employed so that the improved spectra can be verified on a more extensive observational basis. Computed results agree with the observations well. Further comparisons have been made between the proposed spectra and the JONSWAP spectrum. Though the two types of spectrum are close to each other in form, the former shows, as a whole, better agreement with the observation than the latter. By introducing an improved relation between the peak-ness factor and significant wave steepness, the spectrum contains only significant wave height and period as parameters. For spectra given in this form, the computed peak frequencies coincide approximately wit     

Effect of dispersion on impulsive waves

The generation and propagation of surface waves resulting from suddenly created disturbances over water surfaces is investigated. The initial boundary conditions defining the disturbance are given either by a velocity of the free surface, an initial elevation of the free surface or a pressure impulsively applied on the free surface. It is shown that the corresponding three forms of solutions are related by a simple time derivative. Linear solutions are obtained in the cases where the wave motion is assumed to be nondispersive, mildly dispersive and fully dispersive, as well as in the case where the motion is given by the method of stationary phase. Criteria are established to indicate the limit of validity of each method.