水流作用下渔网养殖空间变化的计算方法

渔网的动力分析是养殖网箱设计和优化的基础。通过把一系列杆相互铰接在一起,建立网的模型,模拟网在来流作用下的变形。作用在杆上的水动力可以通过Morison公式来计算,采用有限单元的离散方法,并利用网目合并的方法来减少总的自由度数目。模型的计算结果同试验成果做了对比,计算与试验在柔性网的变形方面,结果吻合良好。     

波浪计算可视化的研究

文章讨论了波浪场可视化实现过程中的一些关键的算法。文中针对表示波浪面的数据集的特性,采用了一种简单的节点法矢量算法。绘制结果表明,用这种简单算法取代二维和三维的数据场节点法矢量的常用算法,能够保持波浪场三维图形的光照效果。利用层次模型算法进行波浪的动态演示,比较了相同面积的波浪场在不同网格密度情况下图形的显示质量,提出波浪场图形质量有与特征波长相匹配的最佳经验网格密度。     

Laboratory study of the dynamics of a layer of turbulence excited by standing surface waves

The evolution of a turbulent layer excited by standing surface parametric waves is studied experimentally. The time dependence of the depth of the turbulized region is obtained. It is found that the thikness of the layer is described by a nonlinear dependence as distinguished from the previously obtained theoretical results. The dynamics of turbulent-layer embedding is described on the basis of a semiempirical theory and the assumption that the outer scale of turbulence is constant. Satisfactory agreement with experimental data is obtained. In the context of the proposed model, a relationship is found between the quantities characterizing the turbulence and surface waves. The dependence of the steepness of surface waves on the acceleration of the bottom is obtained experimentally. The data obtained in this study can be used for estimation of turbulence generation during a submarine earthquake.     

栉孔扇贝成熟卵形态与超微结构的研究

实验研究栉孔扇贝成熟卵的形态与超微结构。观察表明卵子表面呈蜂窝状,无卵极标志。受精前质膜形态模糊,属非典型单位膜。卵质内含有线粒体、内质网、高尔基体等细胞器,但缺乏中心粒复合体。皮层内含有皮层颗粒。卵黄形态不同,来源于多种细胞器。卵子的成熟核相为第一次成熟分裂中期。     

Solution of the problem of propagation of water waves over a pair of asymmetrical rectangular trenches

The problem of propagation of obliquely incident surface water waves over a pair of asymmetrical rectangular trenches in a channel of finite depth is examined for its solution. The mathematical problem is handled for its numerical solution with the aid of a system of singular integral equations of first kind. The resulting integral equations are solved numerically by using suitably designed polynomial approximations of the unknown functions. System of linear algebraic equations is obtained by utilizing the zeros of Chebyshev polynomial of first kind as collocation points and hence the occurrence of ill-conditioned matrix is avoided. The effectiveness of the pair of trenches is studied by analyzing the physical quantities namely the reflection and transmission coefficients. As a special limiting case, the results for a single trench problem are derived and are found to be in excellent agreement with the results available in the literature. The effect of various parameters are analyzed through different graphs for a pair of asymmetrical trenches. The energy balance relation is derived and used to check the accuracy of numerical results.     

AUV定位信号检测延时的蒙特卡洛模拟分析

在简要介绍AUV声学定位声纳接收机原理基础上,分析了CW脉冲信号在极性相关检测电路中的传输过程,建立了极性相关积分检测延时仿真分析模型。提出采用蒙特卡洛模拟方法获取检测延时的分布特征和统计参数的观点。实验结果表明蒙特卡洛模拟实验与硬件电路实验结果一致,对于解决随机性检测延时问题具有很强的能力。获得的结果可为AUV定位声纳检测门限的设定、声学测距和定位精度分析以及水声通信延时分析提供参考。     

尼罗罗非鱼对两种网目定置网片反应特性的比较

本文就尼罗罗非鱼对两种网目(12.6和8.4cm)定置网片的反应特性进行了比较研究。结果表明:在两网片邻近区域内的分布尾次数较中间区域为少;随着时间推移,其分布重心有移向大网目网片一侧的倾向。此外,罗非鱼对两种网目网片的趋网、碰网、穿网尾次数及趋网、碰网、穿网时刻也有一定的差异。     

Nonlinear effects in the process of propagation of internal waves in the presence of turbulence

In the Boussinesq approximation, we study the nonlinear effects observed in the process of propagation of internal waves in the presence of turbulence. The space damping factor of the waves is evaluated. The Stokes drift velocity and the Euler velocity of the mean current induced by waves due to the presence of nonlinearity are determined. It is shown that the principal contribution to the wave transfer is made by the horizontal velocity of the induced current. The Stokes drift is significant only near the bottom. The vertical component of the Stokes drift velocity obtained with regard for the turbulent viscosity is nonzero.     

上海沿岸海域灾害性大风特征研究与预报检验

选取2011-2017年上海沿岸海域5个浮标站点的风场和海浪数据,分析了大风过程的时间和空间特征;对海浪成长过程进行风向分类,运用滑动相关分析统计了8个风向的海浪滞后时间;计算了大风起风时间的预报提前和滞后量,进行了风速风向的误差和准确率检验。结果表明:越往东部海域,大风时数越多,长江口区东部风速较大;大风极值主要出现在8月份台风过程,出现时段都为傍晚到半夜,大浪极值浪向以东北到东南向为主;秋冬季大风时数多,5-6月大风时数最少;大风风向以西北到东北风为主;海浪成长过程风向分布是东南-西北走向,海浪对风的响应滞后时间平均为3~4 h;大风起风时间预报较实况略有滞后,风速预报的准确率总体在70%以上,预报值较实况值偏小,口外浮标偏小最为明显,偏强率都为0;风向预报准确率低,误差大。     

防振锤对深水导管架圆管风致涡激振动抑制研究

研究了阻尼防振锤对深水导管架圆管风致涡激振动的抑制。建立了防振锤动力学模型,分析了防振锤的动力学特性;将在建深水导管架圆管简化为固支梁,建立了结构有限元模型,通过瞬态分析计算了圆管的振动幅值;在圆管中部添加防振锤,分析了防振锤对圆管振动的抑制效果;进行了现场测试,对比了数值模拟和实际测试管道的振动响应。研究表明,文中设计的防振锤可以有效地抑制圆管的涡激共振;数值模拟结果与测试结果非常接近,验证了数值分析方法的有效性。     

A study of hydrodynamics of three-dimensional planing surface

The hydrodynamic problem of 3D planing surface is studied by a finite element approach. The planing surface is represented by a number of pressure patches whose strengths are constant at each element. The unknown pressure strength is obtained by using the free surface elevation condition under the planing surface and Kutta condition at the transom stern. Previous studies indicate that, when the constant pressure distribution method is used, the number of buttocks should be less than five or six, otherwise the calculated pressure distribution will start to oscillate and even become divergent. In the present study, after careful examination of the influence coefficients, it is found that the accuracy of the influence coefficients matrix is very important to the convergence of the solution, especially when the number of elements is relatively high. The oscillation of the pressure distribution can be avoided by constant element method if the influence coefficients are sufficiently accurate. The predicted results of the present paper with more number of buttocks are in good agreement with other researchers'. It is concluded that the irregularity of the pressure distribution found in previous studies is most likely caused by the low accuracy in their calculation of the influence coefficients, not by the method itself.     

Sediment movement characteristics of coast and analysis of seabed evolution

The rotary ring flume is used to study the silty sand movement in a periodic alternating current.Characteristics of sediment movement of different coasts in the tidal current are summarized.More detailed analysis of erosion-sedimentation function in a numerical simulation is made.The equilibrium sediment concentration is advanced.Based on the equilibrium sediment concentration,the seabed erosion-sedimentation index is derived and the seabed erosion-sedimentation calculation is analyzed.The seabed erosion-sedimentation index is used to calculate the seabed evolution of Yangshan sea area and a good agreement with field measurements is obtained.     

Radar studies of the distribution of the formation zones of the first radar echo of hail clouds

The results of studying the regions of hail-cell formation in the North Caucasus are considered. The optimal range of the underlying surface heights for their generation is determined based on an analysis of 392 hail cells. It is shown that the majority of hail cells are formed in the zone where the heights of the underlying surface vary from 900 to 2400 m. The most favorable conditions for the formation of hail clouds are recorded in the northern slopes of the Skalistyi (Rocky) ridge. This region accumulates the main maxima of the frequency of first radar echo recording. The second group of the frequency maxima is located over the Pastbishchnyi (Pasturable) and the Lesistyi (Woody) ridges. The generalized scheme for the region under study is constructed of three zones of generation of the first radar echo of the hail cells. It is shown that approximately 70% of hail clouds are formed over submontane and mountainous regions in the central North Caucasus (zones 2 and 3). The directions of motion of hail cells are quantified for each identified zone.     

海洋观测浮标体水中平衡性分析

海洋观测浮标系统应用广泛,浮标体的平衡性能是影响海洋观测浮标使用的重要因素之一(着重观测波浪等水文参数除外)。以一种主体直径为2.3 m的浮标体为例,运用动力学平衡理论,通过数学分析法进行推演计算,分析后得到了此浮标体的重心和浮心的位置。其中,重心位于主浮体的中轴线偏下位置;按照浮标体倾斜一定角度的情况下,推算出浮标体浮心位置,并由此得出其稳心的位置。依据计算,得出浮标体倾斜20°的情况下,此浮标体依然处于稳态平衡,理论结果表明此浮标体设计具有一定的可行性。通过海上实际测试,验证了理论计算分析的正确性。文中对浮标体平衡性的研究采用了理论分析与实验印证相结合的方法,其分析计算方法具有普适性,适用于其他型号的海洋观测浮标体,乃至所有水面浮体的平衡性分析,可为水面浮体设计提供借鉴。     

《航海图书目录》编制设计研究

分析了《航海图书目录》的编制现状及存在的主要问题,针对其在世界海洋范围的可扩展性,提出了按地理区域单元划分的编制思路,设计了新版目录的基本框架,使得图书检索更为科学,方便用户查阅使用。依据目录索引图的特点,定制了基于数据库驱动的制图流程,有利于生产效率和质量的提升。     

Influence of the discharge of rivers on the formation of level of a closed sea

Within the framework of a two-layer model, we consider the process of, formation of livel in a closed basin under the action of a source with constant flow rate located on its boundary in the upper layer. The response of the level of the basin to the inflow of liquid is observed in the form of the baroclinic and barotropic modes. The baroclinic mode, has the form of an edge wave for which the deviation of level is positive for the upper layer and negative for the lower layer. The barotropic component of the level is almost spatially homogeneous and its intensity increases with time. The increase in the volume of the upper layer caused by the inflow of liquid on the boundary is almost completely attained in the barotropic mode. In the lower layer, the increase in the volume attained in the barotropic mode is completely compensated by the baroclinic edge wave. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

红鳍东方鲀精子形态的研究

实验研究红鳍东方精子形态的超微结构：红鳍东方精子分头部和尾部等两部分。头部似炮弹状,无顶体;核内有空隙,空隙中有或无少量电子致密小颗粒;细胞膜与核膜间的原生质有向外鼓起的单个小液泡;中心粒复合体位于植入窝内,由近端中心粒、中心粒间体和基体等组成。袖套位于核后端,内含７～８个环列的线粒体球。尾部近核端部分鞭毛的一侧有小囊泡群聚的囊泡鞘;远核端部分有侧鳍;囊泡鞘和侧鳍与轴丝的中央微管同在“Ｙ”轴上;轴丝为“９＋２”结构。     

沟纹巴非蛤精子发生过程的超微结构观察

利用透射电镜观察沟纹巴非蛤(Paphia exarataPhilippi)精子的发生和精子的超微结构,揭示了从精原细胞逐渐发育成精子过程中超微结构的变化。其过程主要包括核逐步拉长、染色质浓缩、顶体形成、线粒体逐渐融合、胞质减少以及中心粒演变为轴丝等。精细胞的分化可分为五个时期。成熟精子属原生型,由头部、中段和尾部三部分组成。头部顶体呈圆锥状,其中的顶体物质分布不均匀,基部密度较其他区域高;亚顶体腔呈倒V字型,内含均匀的低密度物质。细胞核卵圆形。中段由4~5个椭圆形线粒体和2个相互垂直的中心粒组成。尾部为典型的“9 2”型结构。     

三种贝类的核型分析

采用体内注射PHA和秋水仙素的方法,利用成体的鳃组织,对毛蚶(Scapharca subcrenata)、长竹蛏(Solen strictus)和菲律宾蛤仔(Ruditapes philippinarus)的核型进行了研究.结果表明毛蚶的2倍体数目为2n=38,核型为18m+16sm+2st+2t,NF=72.长竹蛏的2倍体数目为2n=38,核型为30m+6sm+2t,NF=74.菲律宾蛤仔的2倍体数目为2n=38,核型为28m+10sm,NF=76.     

利用JPL行星/月球星历计算遥感水汽中的地球固体潮改正

简要介绍GPS遥感水汽的原理,详细讨论了计算地球固体潮改正模型的理论公式。介绍获取JPL星历的方法,以及如何利用JPL行星/月球星历来计算太阳和月亮的坐标,并逐步计算出地球固体潮改正。举例计算了地球固体潮改正,分析了其对水汽的影响,比较了太阳距离、月亮距离与地球固体潮改正的关系。