A STUDY OF MOISTURE BUDGET OF A TYPHOON

This paper deals with the study of moisture budget of the typhoon No. 7507. The results show that the mass convergence produced by divergent wind has made the maximum contribution to precipitation, especially at the lower level, accounting for about 70% of the total precipitation, and that the advection term of water vapor is very small. The vertical flux term is to transport water vapor from the lower level to the middle and upper levels, resulting in the increase of water vapor accumulation at these levels. Evaporation term also plays an important role in precipitation, accounting for about 13% of the total precipitation and 23% of the horizontal moisture convergence. The moisture of the typhoon comes mainly from its southern boundary and the secondary inflow of moisture is from its western or eastern boundary. All the inflow layers of these three boundaries are very deep, reaching up to 300 hPa, while the strongest inflow occurs below 700 hPa. In the northern boundary of the typhoon, we obtained that     

登顶冰穹A

北京时间2008年1月10日凌晨，我国第24次南极考察队内陆队已行进至距中山站1172千米处，离南极内陆冰盖最高点Dome—A只剩115千米，此处海拔3910米，已经进入南极内陆Dome-A核心区域。此时，考察队员以及车辆已经出现了高原反映。     

A Time-Domain Coupled Model for Nonlinear Wave Forces on A Fixed Box-Shaped Ship in A Harbor

A 2-D time-domain numerical coupled model is developed to obtain an efficient method for nonlinear wave forces on a fixed box-shaped ship in a harbor.The domain is divided into an inner domain and an outer domain.The inner domain is the area beneath the ship and the flow is described by the simplified Euler equations.The other area is the outer domain and the flow is defined by the higher-order Boussinesq equations in order to consider the nonlinearity of the wave motions.Along the interface boundaries between the inner domain and the outer domain,the volume flux is assumed to be continuous and the wave pressures are equal.Relevant physical experiment is conducted to validate the present model.It is shown that the numerical results agree with the experimental data.Compared with the coupled model with the flow in the inner domain governed by the Laplace equation,the present coupled model is more efficient and its solution procedure is more simple,which is particularly useful for the study on the effect of the nonlinear wave forces on a fixed box-shaped ship in a large harbor.     

A New Model for Ice Forces on A Conical Structure

The ice force is an important factor to be taken into account for offshore structures in cold regions, and the calculation method of the ice force is meaningful for the offshore structure design. The cone is now used as an optimal ice-resistant structure because it can cause bending failure of the ice sheet. The interaction between an ice sheet and a conical structure is studied in this paper and Croasdale‘s model is modified based on field observations. The newly built model separates the ice sheet into the emersed part and the floating part, and the equilibrium analyses are canied out respectively. The bending moment distribution of the ice sheet is analyzed for the determination of the position of bending failure, which serves as a supplementary restraint. The analytic solution of the ice foree on a conical structure is obtained it is verified with the experimental data of previous researches.     

A STUDY OF THE WAVE FORCE UPON A VERTICAL BREAKWATER

Field measurement of waves and wave pressure in a given harbour were carried out in the years 1973 and 1977 and then the statistical analysis was made. Based on this analysis and the linear wave theory some problems concerning the total pressure spectrum and the total pressure crest value and trough value are discussed, and the method of calculating these quantities is given.     

NONLINEAR RESPONSE OF A MOORING-LINE FOR A GIVEN HARMONIC LONGITUDINAL EXCITATION

In the present paper, the resonant response of a vertical mooring-line in neutral buoyancy for a given harmonic longitudinal excitation is discussed. The law of stress-strain is nonlinear. For the above case, a nonlinear equation and corresponding boundary conditions are given. Based on the singular perturbation method, a quasi-periodic solution is obtained. There exists bifurcations through out the resonant region. The stability of the bifurcation solutions is investigated.The method in the present paper can be extended for solving the subharmonic response.     

A NUMERICAL MODEL FOR CALCULATION OF SHORELINE EVOLUTION NEAR A COASTAL STRUCTURE

- A mumerical model for the calculation of shoreline evolution of a straight beach is developed. In this model, the influence of the change of shoreline orientation during evolution on the change of wave refraction is considered. Using this model, the results of computation of the deposition period on the updrift side of a breakwater agree well with the results by a physical model. In computation of the shoreline erosion on the downdrift side of that breakwater, the influence of the variation of longshore breaker height is considered. This model can be used to predict the shoreline erosion-deposition pattern on both sides of a coastal structure on a sand beach or to evaluate the effective service period and the length of sand trapping structure.     

Hydrodynamic Coefficients and Wave Excitation Forces for A Ship near A Quay

In this paper,the effects of a quay or a solid jetty on hydrodynamic coefficients and vertical wave excitation forces on a ship woth or without forward speed are discussed.A modified simple Green function technique is used to calculate the 2D coefficients while the strip theory is used to calculate the 3D coefficients. Wave excitation forces are also calculated with the strip theory. Numerical results are provided for hydrodynamic coefficients and vertical wave excitation forces on a 200000 DWT tanker ship. It is found that the quay has a considerable effect on the hydrodynamic coefficients and wave excitation forces for a ship.     

A Vertical Two-Dimensional Model to Simulate Tidal Hydrodynamics in A Branched Estuary

A vertical (laterally averaged) two-dimensional hydrodynamic model is developed for tides, tidal current, and salinity in a branched estuarine system. The goveming equations are solved with the hydrostatic pressure distribution assumption and the Boussinesq approximation. An explicit scheme is employed to solve the continuity equations. The momentum and mass balance equations are solved implicitly in the Cartesian coordinate system. The tributaries are govemed by the same dynamic equations. A control volume at the junctions is designed to conserve mass and volume transport in the finite difference schemes, based on the physical principle of continuum medium of fluid. Predictions by the developed model are compared with the analytic solutions of steady wind-driven circulatory flow and tidal flow. The model results for the velocities and water surface elevations coincide with analytic results. The model is then applied to the Tanshui River estuarine system. Detailed model calibration and verification have been conducted with measured water surface elevations,tidal current, and salinity distributions. The overall performance of the model is in qualitative agreement with the available field data. The calibrated and verified numerical model has been used to quantify the tidal prism and flushing rate in the Tanshui River-Tahan Stream, Hsintien Stream, and Keelung River.     

A Study on Crack Detection with Modal Parameters of A Jacket Platform

Crack detection procedures by different modal parameters are analyzed for identitying a crack and its location and magnitude in a jacket plafform. The first ten natural frequencies and modal shapes of the jacket models are obtained by numerical experiments based on NASTRAN Code. A crack at different locations and of different magnitudes is imposed in the model at the underwater beams. Then, the modal evaluation parameters are calculated numerically, to illustrate the evaluation of modal parameter criteria used in jacket crack detection. The sensitivities of different modal parameters to different cracks are analyzed. A new technique is presented for predicting the approximate location of a breakage in the absence of the data of an intact model. This method can be used to detect a crack in underwater menbers by use of incomplete mode shapes of the top members of the jacket.     

A Numerical Study on the Asymmetric Water Entry of A Wedge Section

The effect of the asymmetric water entry over a submerged part of a ship on the hydredynamic impact is investigated numerically. A wedge hotly is considered and the problem is assumed to be two-dimensional. The results of symmetric and asymmetric impacts are compared. The effect is found significant in the numerical simulation. The maximum hydrodynamic pressure at a heel angle of 10 degrees becomes about 95% more than that of the symmetric entry. The result of the present work proves the importance of asymmetrical hydrodynamic impact loading for structural design of a ship. Besides, the numerical procedure is not limited to a wedge type cross section and it is possible to apply it for any real geometry of ships and high-speed craft.     

Dynamic Analysis of A Pontoon-Separated Floating Bridge Subjected to A Moving Load

1 .Introduction Since the most significant feature of a movingloadisits mobility,the interaction betweenthe ve-hicle and bridge is very complicated,which can be classified as a coupled vibration problem.There-fore ,much attention has been paid to the dyna…     

The Structure of A Turbulent Jet in A Crossflow-Effect of Jet-Crossflow Velocity

A comprehensive numerical study on the three-dimensional structure of a turbulent jet in crossflow is performed. The jet-to-crossflow velocity ratio (R) varies in the range of 2 - 16; both vertical jets and inclined jets without excess streamwise momentum are considered. The numerical results of the Standard two-equation k-ε model show that the turbulent structure can be broadly categorised according to the jet-to-crossflow velocity ratio. For strong to moderate jet discharges, i.e. R> 4, the jet is characterized by a longitudinal transition through a bent-over phase during which the jet becomes almost parallel with the main freestream, to a sectional vortex-pair flow with double concentration maxima; the computed flow details and scalar mixing characteristics can be described by self-similar relations beyond a dimensionless distance of around 20-60. The similarity coefficients are only weakly dependent on R. The cross-section scalar field is kidney-shaped and bifurcated, vvith distinct double concentr     

Diffraction of Water Waves by A Vertically Floating Cylinder in A Two-Layer Fluid

In this paper, the diffraction of water waves by a vertically floating cylinder in a two-layer fluid of a finite depth is studied. Analytical expressions for the hydrodynamic loads on the vertically floating cylinder are obtained by use of the method of eigenfunction expansions. The hydrodynamic loads on the vertically floating cylinder in a two-layer fluid inelude not only the surge, heave and pitch exciting forces due to the incident wave of the surface-wave mode, but also those due to the incident wave of the internal-wave mode. This is different from the case of a homogenous fluid. Some given examples show that, for a two-layer fluid system with a small density difference, the hydrodynamic loads for the surface-wave mode do not differ significantly from those due to surface waves in a single-layer fluid, but the hydrodynamic loads for the internal-wave mode are important over a wide range of frequencies. Moreover, also considered are the free surface and interface elevations generated by the diffraction wave due to the incident wave of the surface-wave and interhal-wave modes, and transfer of energy between modes.     

A水道反舰作战

一、整体情况红方(L 国)所属 L 岛发生受到蓝方支持的武装叛乱,蓝方海军组建了一支援助 L 岛的部队,其中一部分已在近日空运到达 L 岛,载有重装备和弹药的护航运输队已进至 X 国海域,正向 L 岛驶去。L 国北部与 X 国的 K 岛之间水道为蓝方护航运输队必经航线。为粉碎蓝方叛乱分子的支援企图,红方决     

附录A SWAMP参加者

模 式名研 究 单 位D 研 究 者MR本气象厅气象研究apan Tsukuba)Takeshi U 【二盯1雹**0*en0 引u口10*川la Ulll*口01*a 0引18 br口1101 皿**目*。D 乙010 乙a可*三er 一 一【IweD1*e.且雹幼yJ 可_至_皙气__L_J”———一’一‘”LliC1818b6ttO IrtSSOC1821Olls STtiQIO 卜Oft6lltl oDQ6.(YSQli ltslyjlSA大西洋悔洋学和气象学实验室,美国国家海洋大气局(Miami,Florida USA)yincent CordoneLiada LawsonArthur Gree口 woodRof)ert Long I__。,____、,_,。__。,I、、.1。。t..__..TT,A、【T…     

A Model for the Calculation of Velocity Reduction Behind A Plane Fishing Net

1 .IntroductionOpen oceanaquacultureis becominga newfisheriesindustryasthe human demandfor seafoodin-creases .Consideringthe requirement of environmental protection,thelackof suitable shelteredsitesisforcingfishfarmers to move to more exposed offshore loc…     

A Three-Point Method for Separating Incident and Reflected Waves over A Sloping Bed

This study presents a three-point method for separating incident and reflected waves to explain normally incident waves' propagating over a sloping bed. Linear wave shoaling is used to determine changes in wave amplitude and phase in response to variations of bathymetry. The wave reflection coefficient and incident amplitude are estimated from wave heights measured at three fixed wave gauges with unequal spacing. Sensitivity analysis demonstrates that the proposed method can predict the reflection and amplitude of waves over a sloping bed more accurately than the two-point method.     

A new family of polychaeta-Euniphysidae

Euniphysa, originally a genus of the family Eunicidae, was erected by Wesenberg-Lund in 1949, and for a longtime there has been only one species in this genus. The present report is based on our samples collected from the South China Sea, and we consider that the differences between Euniphysa and Eunice are very significant: Five occipital tentacles distributed unequidistantly; the jaw consists of 6 pairs of maxillary plates; the body may be divided into anterior region and posterior region, etc. Therefore we suggest that Euniphysa should be separated from Eunicidae, and become a new family Euniphysi-dae. At present this family includes 3 genera, namely, Euniphysa , Paraeuniphysa and 1 new genira Heterophysa; Totally there are 7 species, including 3 new species and 1 new combination species.