误差方差二次型估计模型的转化

研究一般的回归模型中误差方差的二次型估计的容许性，研究方法是模型的整体转化和局部转化，结果有：（１）二次约束下的线性模型等价于相应的无约束的线性模型。（２）线性（齐次或非齐次）等式约束下的线性模型等价于某个无约束的线性模型。（３）单个非齐次不等式约束下的线性模型等价于某个无约束的线性模型。（４）通过例子证明了多个线性不等式约束的线性模型不能等价于某个无约束的线性模型。（５）某类非齐次二次型估计的容许性等价于相应的齐次二次型估计的容许性     

SPH Numerical Modeling for the Wave-Thin Structure Interaction

In this paper, a numerical model of 2D weakly compressible smoothed particle hydrodynamics (WCSPH) is developed to simulate the interaction between waves and thin structures. A new color domain particle (CDP) technique is proposed to overcome difficulties of applying the ghost particle method to thin structures in dealing with solid boundaries. The new technique can deal with zero-thickness structures. To apply this enforcing technique, the computational fluid domain is divided into sub domains, i.e., boundary domains and internal domains. A color value is assigned to each particle, and contains the information of the domains in which the particle belongs to and the particles can interact with. A particle, nearby a thin boundary, is prevented from interacting with particles, which should not interact with on the other side of the structure. It is possible to model thin structures, or the structures with the thickness negligible with this technique. The proposed WCSPH module is validated for a still water tank, divided by a thin plate at the middle section, with different water levels in the subdomains, and is applied to simulate the interaction between regular waves and a perforated vertical plate. Finally, the computation is carried out for waves and submerged twin-horizontal plate interaction. It is shown that the numerical results agree well with experimental data in terms of the pressure distribution, pressure time series and wave transmission.     

SPH Numerical Modeling for the Wave–Thin Structure Interaction

In this paper, a numerical model of 2D weakly compressible smoothed particle hydrodynamics (WCSPH) is developed to simulate the interaction between waves and thin structures. A new color domain particle (CDP) technique is proposed to overcome difficulties of applying the ghost particle method to thin structures in dealing with solid boundaries. The new technique can deal with zero-thickness structures. To apply this enforcing technique, the computational fluid domain is divided into sub domains, i.e., boundary domains and internal domains. A color value is assigned to each particle, and contains the information of the domains in which the particle belongs to and the particles can interact with. A particle, nearby a thin boundary, is prevented from interacting with particles, which should not interact with on the other side of the structure. It is possible to model thin structures, or the structures with the thickness negligible with this technique. The proposed WCSPH module is validated for a still water tank, divided by a thin plate at the middle section, with different water levels in the subdomains, and is applied to simulate the interaction between regular waves and a perforated vertical plate. Finally, the computation is carried out for waves and submerged twin-horizontal plate interaction. It is shown that the numerical results agree well with experimental data in terms of the pressure distribution, pressure time series and wave transmission.     

非结构网格生成法在二维潮流数学模型中的应用

文章基于Delaunay三角化的思想实现了非结构化数值网格生成技术,并LOP(Local Optimization Procedure)算法对网格进行了优化。用有限体积法在非结构三角形网格上对平面二维潮流方程进行了数值求解。实例应用分析表明,文中的数值网格生成技术和有限体积方法相结合用于求解具有复杂几何边界区域内的潮流问题能取得很好的结果。     

考虑摩擦的绕岛理论及在印尼贯穿流流量估算中的应用

基于Godfrey绕岛理论,在正压、线性模型下同时考虑了底摩擦和侧摩擦,得到带有摩擦的绕岛理论。根据两个岛屿的经向长度不同,将其分为3种情况;通过积分动量方程,分别得到了各自的带有摩擦的岛屿流函数解析解,从而得到两岛屿间流量公式。当忽略侧摩擦或底摩擦中的一个时,可得Wajsowicz的带有摩擦的绕岛理论。利用CCMP的风场数据,计算了印尼贯穿流的流量,通过比较发现,当只考虑侧摩擦时,流量会增加;当只考虑底摩擦时,流量会减少;当同时考虑底摩擦和侧摩擦时,流量会减少,减少的幅度较只考虑底摩擦时更大。与不考虑摩擦时相比,同时考虑摩擦和侧摩擦时的流量减少量不超过25%。     

A note on using the accelerated convergence method in climate models

Application of the accelerated convergence (or asynchronous integration) method of Bryan (1984) to climate problems with time‐dependent forcing is investigated using an ocean general circulation model (GCM), with an idealized box ocean and forced with an idealized seasonal restoring surface temperature. Numerical experiments consist of a control experiment, which is integrated synchronously for 9000 years, and 2 experiments with asynchronous integration, one with depth dependent acceleration and one with depth independent acceleration. The latter 2 cases were integrated synchronously for 9000 years after asynchronous equilibria are reached. It is found that a few thousand years of synchronous integration is needed to reach a new equilibrium after asynchronous equilibrium is obtained, consistent with a scaling argument. However, at the new equilibrium, temperature in the deep ocean only differs from that of the early stage of synchronous adjustment by about 0.01°C. So for practical purposes, 50 years of synchronous integration beyond asynchronous equilibrium is sufficient. A simple interpretation of the accelerated convergence method of Bryan is also presented.     

基于GF-1卫星遥感影像的海岸线生态化监测与评价研究——以营口市为例

海岸线是海洋与陆地的分界线,也是重要的生态交错线。本文采用GF-1卫星遥感影像,通过监测大潮高潮时刻和小潮低潮时刻海岸水陆边界线,构建了潮间带完整性系数,以此为依据将海岸线划分为自然海岸线、具有基本生态功能的人工海岸线、具有部分生态功能的人工海岸线、具有有限生态功能的人工海岸线、具有少量生态功能的人工海岸线和无生态功能的人工海岸线。在此基础上,结合潮间带完整性系数及其毗邻海岸线长度,构建了海岸线生态化指数,用以评价区域海岸线的生态化程度。营口市海岸线以无生态功能的人工海岸线、自然海岸线和具有少量生态功能的人工海岸线为主,分别占到海岸线总长度的45.74%、18.31%和15.53%。营口市总体海岸线生态化指数为0.29,其中西城区、老边区、盖州北、鲅鱼圈区和盖州南分别为0.55、0.17、0.40、0.10和0.55。     

黄河口新口门海域流场分析

1996年9月在黄河口新口门附近海域设置3个断面9个站位,对海流、水温、盐度和含沙量进行了连续2个潮周期多层次同步观测。结果表明：新口门属不正规的半日潮型。流速口门前大于两侧,左侧最小,深水区大于浅水区,流速垂向分布呈不均匀现象,表层大于底层频率最高。含沙量垂向分布为上小下大,泥沙输移方向口门处与径流方向一致,其它部位与潮汐相对应。泥沙扩散范围达500km^2。     

Sea ice growth at nonstationary ocean-atmosphere heat exchange

A thermodynamic model of sea snow-ice cover growth under the influence of heat flows on its upper and lower surfaces is presented. The growing is described with an extended region of phase transition (a two-phase region) with a linear temperature distribution. The temperature of the upper surface is calculated with the use of a heat-balance equation on the basis of determinable meteorological observation data. The comparison of the model results with freezing experimental data is performed.     

开孔沉箱在斜向入射波作用下受力研究

应用透空壁内流体速度与壁两侧的压力差成正比的线性模型,研究了斜向波与无限多个开孔沉箱的相互作用.依照结构物的几何形状,把整个流域分成无限多个子域,在每个子域内应用特征函数展开法对速度势进行展开.对于沉箱内的波浪运动,引入相位差概念;在构造反射波模型时,考虑了结构物的几何形状影响.列举出物理模型实验结果与数值实验结果的比较,可以看出两者吻合较好.进一步的数值计算验证表明,当孔隙系数无限大时,开孔墙前后的速度非常接近.在低频入射波作用下,垂直于沉箱的水平力随角度的变大而减小,平行于沉箱排列方向的力则变大.     

Numerical Experiment on Two-Dimensional Line Thermal

The time evolution of a two-dimensional line thermal-a turbulent flow produced by an initial element with signifi-cant buoyancy released in a large water body, is numerically studied with the two-equation k - e model for turbulence closure. The numerical results show that the thermal is characterized by a vortex pair flow and a kidney shaped concentra-tion structure with double peak maxima; the computed flow details and scalar mixing characteristics can be described by self-similar relations beyond a dimensionless time around 10. There are two regions in the flow field of a line thermal: a mixing region where the concentration of tracer fluid is high and the flow is turbulent and rotational with a pair of vortex eyes, and an ambient region where the concentration is zero and the flow is potential and well-described by a model of doublet with strength very close to those given by early experimental and analytical studies. The added virtual mass coeffi-cient of the thermal motion is found to be approximat     

深潜器大开口球形耐压操纵舱结构模型的力学性能

结合模型试验和数值计算对大潜深、带大开口的球形耐压结构静态力学性能进行了研究。研究中考虑到材料非线性、非弹性的因素,通过对材料拉伸试验曲线的分析,得到了材料应力-应变的近似表达式;并且利用超声测厚仪对结构模型的几何缺陷进行了测量。同时基于参数化设计语言建立了有随机几何缺陷的有限元模型,并利用接触单元考虑了大开口观察窗与耐压结构的联系。试验验证表明论文提出的利用有限元软件分析大潜深、大开口耐压壳体力学性能的计算方法和计算策略是准确可靠的,所获得的结果可供设计使用。     

A numerical study of second-order springing of an elastic body using higher-order boundary element method (HOBEM)

Second-order springing on an elastic body with forward speed is analyzed by numerical simulations. The boundary-value problem for the velocity potential is solved by means of the direct time-domain higher-order boundary element method (HOBEM). The free-surface boundary condition in the boundary-value problem is approximated on the mean surface up to second order by use of perturbation and Taylor-series expansion methods. The body boundary condition for an elastic body is derived with various quantities which are redefined in the generalized mode. These variables such as mode shape, normal vector, etc. are obtained by using directional derivative and continuum mechanics, and the same mathematical expressions are used to obtain several second-order generalized forces. To validate the numerical results, the second-order hydrodynamic force on the bottom-mounted rigid/elastic cylinders without forward speed is compared with other semi-analytic results. The property of second-order forces on an elastic ship is studied by changing the flexural rigidity and forward speed with elastic response. It is confirmed that the second-order velocity potential is important for a body with forward speed and investigation should be made more on numerical methods for accurate computation of the second-order velocity-potential force with forward speed.     

Analysis of seabed instability using element free Galerkin method

Wave-induced seabed instability, either momentary liquefaction or shear failure, is an important topic in ocean and coastal engineering. Many factors, such as seabed properties and wave parameters, affect the seabed instability. A non-dimensional parameter is proposed in this paper to evaluate the occurrence of momentary liquefaction. This parameter includes the properties of the soil and the wave. The determination of the wave-induced liquefaction depth is also suggested based on this non-dimensional parameter. As an example, a two-dimensional seabed with finite thickness is numerically treated with the EFGM meshless method developed early for wave-induced seabed responses. Parametric study is carried out to investigate the effect of wavelength, compressibility of pore fluid, permeability and stiffness of porous media, and variable stiffness with depth on the seabed response with three criteria for liquefaction. It is found that this non-dimensional parameter is a good index for identifying the momentary liquefaction qualitatively, and the criterion of liquefaction with seepage force can be used to predict the deepest liquefaction depth.     

An iterative method for boundary element solution of large offshore structures using the GMRES solver

The GMRES approach is used to solve complex matrix solution arising from boundary element analysis of large offshore structures. This makes it possible to solve problems with large numbers of panels on a workstation with a much smaller memory than typical high performance computers. The speed of the solver is compatible with direct solvers when the enough RAM is available. Otherwise, an iteration procedure can be used. By using an out-of-core treatment, typical RAM requirement is reduced to a size approximately linearly proportional to the panel number n instead of being proportional to n². The code is first verified with direct solver for cases with small number of panels. The applicability to large offshore structure of the model is demonstrated for a TLP case.     

非线性波传播的新型数值模拟模型及其实验验证

以一种新型的Boussinesq型方程为控制方程组,采用五阶Runge-Kutta-England格式离散时间积分,采用七点差分格式离散空间导数,并通过采用恰当的出流边界条件,从而建立了非线性波传播的新型数值模拟模型.通过对均匀水深水域内波浪传播的数值模拟说明,模型能较好地模拟大水深水域和强非线性波的传播.通过设置不同的入射波参数来进行潜堤地形上波浪传播的物理模型实验,并将数值解与物理模型实验结果进行了比较.     

一种浅水型海流定点观测系统布放方法

介绍了采用座底式轻型仪器架进行30 m以内浅水深海流观测的两种系统布放方法:先锚后仪器架法和先仪器架后锚法。其中,详细介绍了先锚后仪器架法的布放过程,对先仪器架后锚法作了简要介绍。     

浅海有限面积源的噪声场空间相关特性研究

本文对有限面积噪声源产生的噪声场的空间相关特性作了讨论。分别研究了接收器处于源区域里面和外面的情形。对一浅海典型声速剖面和 Baltic海区的噪声场相关特性及噪声场强度进行了计算 ,并与无限大噪声源平面的噪声场特性作了比较。同时 ,为把连续谱考虑在内 ,引入一虚假深海底 ,用复模式和来近似计算分支割线的贡献。但当接收器远离源区域时 ,连续谱经过在下介质中的长程传播 ,衰减迅速 ,故其对噪声场的贡献可以忽略 ,而仅考虑离散简正波场的贡献。结果发现 ,有限面积源的噪声场结构无论是水平结构 ,还是垂直结构均是不均匀的 ,都依赖于接收场点的绝对位置。这与无限大噪声源平面所形成的噪声场的特性是不一样的     

海上某油田防膨剂的筛选与评价

针对海上油田储层特点筛选黏土防膨剂,对控制储层水敏伤害和保障整个油田的持续高效开发有非常重要的意义。综合多种防膨剂评价方法的长处,采用静态与动态相结合的实验评价方法,筛选了适用于海上某油田注水开发的黏土防膨剂。对于优选出质量分数为1％的FP一3A黏土防膨剂,静态评价离心法防膨率为79．1％,X．射线衍射法防膨率为54．6％,膨胀仪法防膨率为80．7％,岩心线性膨胀率为0．73％,每100g静态吸附量0．29g;动态评价渗透率保留率大于70％,最佳注入浓度0．5％～1．0％,且渗透率波动范围小,防膨效果稳定且作用时间长,适于海上某油田注水开发应用。     

中西太平洋金枪鱼围网渔场聚类及其原因分析

本文根据1995-2010年我国中西太平洋金枪鱼围网生产统计数据,按年和月不同时间空间分辨率对金枪鱼围网渔场进行聚类分析,划定不同渔场类型;同时结合海表温度（SST）及Niño3.4区指数,探讨其渔场类型形成的原因。研究表明,在月为时间尺度下气候异常事件（El Niño和La Niña事件）发生频次与渔场聚类结果类别相关联,在1-12月发生气候异常事件频数分布可划分为以下几个阶段:1-3月、4-6、7-9月、10-12月,与月时间尺度下金枪鱼围网中心渔场4种聚类结果的时间范围具有一致性。通过渔场重心聚类结果和El Niño和La Niña事件分类统计对比发现,在年时间尺度下,气候异常事件的类型与聚类结果相关联,聚类结果同一类别包含的年份发生的气候异常事件具有一致性,即在同一类别下1995年、1997年为强El Niño年;1998年、2007、年、2009年为正常年份;2010年为强La Niña年;1999年、2000年、2001年为La Niña年;1996年、2008年为La Niña年;2002年、2004年为El Niño年。研究认为,中心渔场的年际聚类变化与El Niño、La Niña事件的发生分布具有很强的相关性,因此可以利用El Niño、La Niña指标来预测渔场的年间和月份间的变化。