LAGFD-WAM numerical wave model——Ⅰ. Basic physical model

The LAGFD-WAM wave model is a third generation wave model. In the present paper the physical aspect of the model was shown in great detail including energy spectrum balance equation, complicated characteristics equations and source functions.     

An oceanic reverberation model

A simple model of the surface, volume, and bottom reverberation received by a moving platform as a function of time following the tranmission of a narrow-band pulsed signal is described. Both the time-varying power level and the underlying power spectrum are predicted. The model includes the effects of platform motion, transmit signal windowing, transmit and receive beam patterns, and the environment (surface, volume, and bottom backscattering strengths, the scatterer velocity distributions for surface waves and current layers, and sound absorption). An isospeed sound speed profile is assumed and reflections at the surface and bottom boundaries are not permitted. Also described is a matched filter-envelope detector receiver model for post processing of the reverberation spectra.     

General longshore transport model

In the present paper a general longshore transport (LT) model is proposed after a re-calibration of the model originally introduced by Lamberti and Tomasicchio (1997) based on a modified stability number, N_s^⁎⁎, for stone mobility at reshaping or berm breakwaters. N_s^⁎⁎ resembles the traditional stability number (Ahrens, 1987; van der Meer, 1988) taking into account the effects of a non-Rayleighian wave height distribution at shallow water (Klopman and Stive, 1989), wave steepness, wave obliquity, and nominal diameter of the units. Nine high-quality data sets from field and laboratory experiments have been considered to extend the validity of the original model for a wider mobility range of the units: from stones to sands. The predictive capability of the proposed model has been verified against the most popular formulae in literature for the LT estimation of not cohesive units at a coastal body. The comparison showed that the model gives a better agreement with the physical data with respect to the other investigated formulae.The proposed transport model presents a main advantage with respect to other formulae: it can represent an engineering tool suitable for a large range of conditions, from sandy beaches till reshaping breakwaters.     

基于空间自回归和空间聚类的渔情预报模型

作者针对远洋渔场渔情预报精度偏低的问题,提出一种基于空间自回归和空间聚类的渔情预报模型。该模型利用空间自回归对收集到的渔业历史数据进行预处理,然后通过空间聚类将所有数据样本根据地理位置分划成若干个区域,最后研究每个区域中环境数据与渔获数据之间的数学关系,各自建立栖息地适宜性指数模型(Habitat Suitability Index,HSI),并以印度洋大眼金枪鱼(Thunnus obesus)为例进行验证。结果表明,本模型的均方差为0.1742,与传统线性回归方法的均方差0.2363相比,能更好地表达海洋环境数据与渔获量之间的关系,预测精度显著提高。     

渤海冰-海洋耦合模式——I．模式和参数研究

在国内外冰-海洋耦合模式研究基础上，根据渤海水文、气象和冰情特点，以国家海洋环境预报中心的渤海海冰预报模式和POM海洋模式为基础，开发了一个冰-海洋耦合模式．在该耦合模式中，冰和海洋之间的动量和热量交换是双向的，冰厚和冰密集度的变化不仅由冰表面和冰底的热收支决定，还由开阔水的表面热收支决定．侧重阐述了耦合模式的动力和热力学过程的耦合，并对模式中一些热力参数进行了讨论．     

The synchronous coupling of a third-generation wave model and a two-dimensional storm surge model

The interaction of waves and currents is studied by the dynamical coupling of a third generation wave model and a two-dimensional storm surge model. The coupling process of the two models is implemented synchronously. To estimate the effects of waves on the generation of storm surges, the theory of Janssen is used. The effects of the wave radiation stress on surge levels and the effects of storm-induced currents on waves are also investigated.The coupled wave and storm surge models have been tested by hindcasting two storm events in the northern South China Sea. The use of the Simth and Banke stress relation underestimates the surges by 10%. The inclusion of the radiation stress improves the accuracy of the computed results slightly by 2%. The introduction of a wave-dependent surface drag gives a significant improvement. The storm-induced currents clearly affect the wave characteristics at the peak stage. However, as far as the prediction of wave height is concerned, it is better not to consider the wave radiation stress in the storm surge model unless this is accompanied by a wave-dependent surface drag.     

A nearshore wave breaking model

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Management of the coastal-sea-zone-ecosystem model

We present a model of the processes of development in the ecosystem of the coastal zone of the sea constructed by the method of adaptive balance of causes (ABC-method). The model contains nine variables (phyto- and zooplankton, fish larvae, fishes, oxygen, carbon dioxide, salinity, biogenic elements, and detritus) affected by the solar radiation, surface wind, sea temperature, and river discharge. The equations of the model contain control agents governing the dependences of the elements of the food chain on the vitally important resources and environmental conditions. The scenarios of the processes of development are constructed for the simulated annual courses of external actions. The possibility of management of fish resources by regulating the flows of biogenic elements and detritus with river discharge is discussed. A mechanism of management based on the monitoring of the concentration of dissolved oxygen in seawater is proposed. The numerical experiments show that the ABC-model of the processes of development in the ecosystem of the coastal zone of the sea makes it possible to simulate the scenarios of regulation of the flows of biogenic elements and detritus into the sea with an aim of preservation of of fish resources. Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 36–49, January–February, 2009.     

一种近岸区波浪破碎模型

从波浪破碎的能量关系入手,以紊流能量方程为基础,考虑破碎区内单个波在不同破碎阶段所提供的紊动能量强度的变化过程,提出了一种波浪破碎模式.通过将这一模型引入Boussinesq方程中,初步建立了一种近岸区波浪变形数学模型,并用波浪水槽实验资料对模型模拟波高和平均水位的情况进行了初步验证,得到了良好的结果.     

A model for Meddy formation

A particular feature of “Meddies” is that the water within them has stable gradients of salinity and temperature. In this paper a model for a dense turbulent plume falling in a stationary, linearly-stratified environment is described. The density of the plume is assumed to be a linear function of two components, while the ambient density gradient is due to a gradient in only one of these components (labelled component one). The ratio of the contributions to the source buoyancy flux of the two components within the plume is identified as the important parameter for this type of flow. After deriving the steady equations for the plume, a simplified model for the filling process which creates the Meddy is described, which shows how a layer of fluid may be formed with stable gradients in both components in the lower part of the intrusion. The intrusion is shown to be less stratified than the surrounding fluid, with relatively weak gradients in component one (identified with temperature in the Meddy) that vary from unstable at the top to stable at the bottom of the intrusion and a fairly constant (stable) gradient in the second component (salinity for a Meddy). If the stable gradients in a Meddy are due solely to the filling process then, during formation, the top of the Meddy must become cooler than the surrounding water at the same level. The observed stable temperature gradient in Meddies is likely to be due to mixing processes after their formation, whereas the stable salanity gradient is mainly due to the filling process during formation.     

Limitations of the streamtube model

A common feature of one-dimensional streamtube models is that the pressure gradient includes only the effect of the density difference between the plume and the ambient water on a sloping bottom. Variations of the streamtube height and density along the flow path are thus neglected. In the present paper a streamtube model is used to highlight the assumptions underlying the simplification and to obtain the limitations this prerequisite presents. The results indicate that the parameter range for which the simplification is applicable is largest when the initial outflow is parallel to the isobaths. More specific limits are given for three major outflows — the Mediterranean, the Faroe Bank Channel and the Denmark Strait outflow.     

超细长三体船耐波性试验研究

通过三体船模型耐波性试验,包括横摇试验,规则波中的迎浪试验,研究了侧体布置位置和舭龙骨对三体船横摇运动的影响以及在波浪中的纵摇和垂荡运动特点。     

土壤-地雷共振系统模型解析

在研究土壤-地雷共振系统模型的基础上,提出一种共振与反共振相结合的声波探雷模型.根据地雷顺性大及低频声学的特征,把地雷与其上方的土壤分别等效为弹簧和质量块,构成质量-弹簧共振系统,通过对系统频响函数的解析,讨论模型的共振与反共振现象.通过实验发现有、无地雷的地表振动速度比值存在大于1的极大值频率点和小于1的极小值频率点交替出现的现象,与理论预测符合.表明土壤-地雷共振系统同时存在共振与反共振现象,可用于地雷成像的研究.     

冰与结构的耦合振动模型

针对冰与结构的相互作用问题进行了分析研究。在Ｓｏｄｈｉ模型的基础上提出一种新的冰与结构的耦合振动模型。通过引入冰板破坏长度的特征参数,将冰与结构的耦合作用分为加载、穿透和分离三种典型状态,给出了各种状态下的运动方程和求解方法及不同状态间的转化关系,从而获得结构冰致振动的稳态周期响应,并运用这一模型对结构与冰的各种参数的影响作了系统研究。结果表明,本模型适用于相当宽的冰和结构的参数范围及冰板弯曲的屈     

Implementation of state-dependent plasticity model in strain wedge model for laterally loaded piles in sand

ABSTRACT

The strain wedge model effectively performs nonlinear analyses of the lateral response of piles by using a nonlinear stress-strain relationship to describe soil behavior in the strain wedge. In this study, a state-dependent plasticity model has been implemented in the strain wedge model to calculate the stress-strain relationship for sand in the strain wedge. To complement this implementation, the effect of dilatancy on the shear strain is considered in the strain wedge. A full-scale test and a 45 g centrifuge model test on laterally loaded piles are used to validate the proposed method. The results show that the deflections and moments predicted by the proposed method accord well with those measured from full-scale and centrifugal model pile tests. Moreover, the combination of the state-dependent plasticity model and the strain wedge model allows for analyzing the lateral response of single piles using a unique set of model parameters for different relative densities of sands. In addtion, the stress-strain response in the strain wedge, not the dilatancy, dominates the soil resistance in the strain wedge and thus the lateral response of piles.     

A coupled ice-ocean model for the Bohai Sea I. Study on model and parameter

1 IntroductionAs an important compartment of global cli-mate system, the development and variation ofsea ice directly affect the global atmosphere andocean environment, especially the deep watersformation and circulation. Therefore, it be-comes one of the keys of the global climatestudy to explore the coupling physical processof sea ice to atmosphere and ocean in the cli-mate system and to set up the global coupledairiceocean system. The studies on the in-teraction of iceocean and its coupled…     

涡分辨率海洋模式及其海气耦合模式中吕宋海峡处的黑潮入侵

比较了准全球涡分辨率海洋模式（简记为LICOMH）及其海气耦合模式（简记为LICOMHC）中的黑潮入侵南海与观测中黑潮入侵的差异。我们发现在单独海洋模式中黑潮入侵与观测相比过强,而在其海气耦合模式中这一差异得到了改善。冬季的吕宋海峡输送（LST）在LICOMH中为-8.8×10⁶ m³s^-1,而在LICOMHC中则下降到-6.0×10⁶ m³s^-1 。进一步的研究表明是大尺度风场,局地风应力和吕宋海峡以东中尺度涡旋的共同作用导致了黑潮入侵在两个模式中的不同。LICOMH中吕宋岛东北部相对较强的气旋导致了较弱的黑潮输送及吕宋海峡处较强的黑潮入侵。以上三者共同作用造成的LST差异大约是2.0×10⁶ m³s^-1,与两个模式间的LST差异大小基本相当。进一步对LICOMH与LICOMHC中的EKE收支进行分析表明,LICOMH中更强的EKE输送及斜压转换项导致了黑潮以东存在更强的气旋,而海表风场对两个模式中的涡旋差异贡献极小。     

Applications of sediment sudden deposition model based on the third-generation numerical model for shallow water wave

The existing numerical models for nearshore waves are briefly introduced, and the third-generation numerical model for shallow water wave, which makes use of the most advanced productions of wave research and has been adapted well to be used in the environment of seacoast, lake and estuary area, is particularly discussed. The applied model realizes the significant wave height distribution at different wind directions. To integrate the model into the coastal area sediment, sudden deposition mechanism, the distribution of average silt content and the change of sediment sudden deposition thickness over time in the nearshore area are simulated. The academic productions can give some theoretical guidance to the applications of sediment sudden deposition mechanism for stormy waves in the coastal area. And the advancing directions of sediment sudden deposition model are prospected.     

基于致动线模型的错列式两风机尾流场数值模拟

风电场中风机之间存在十分复杂尾流相互干扰现象,尾流相互干扰效应对风机的功率输出、叶片载荷等产生十分显著的影响。采用致动线模型以及计算流体力学方法,研究两风机之间的复杂尾流干扰效应。在保持两风机纵向间距一样的情况下,考虑两风机在不同横向间距下,数值模拟两风机的部分尾流相互干扰现象,分析两风机的气动功率输出特性、尾流速度变化特性、风轮平面附近轴向诱导因子分布特性,尾涡结构以及尾流干扰效应。数值模拟结果表明:在上下游风机在沿着流向方向距离保持不变的情况下,随着横向间距的变化,上下游风机的尾流存在十分复杂的尾流相互干扰效应,对下游风机的气动功率输出以及两风机风电场的整体流场产生了显著的影响。