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1.
The history of the definition of salinity and the methods of computing It are traced from the beginning of the twentieth century until the present. Difficulties that have arisen in existing practices are discussed, in particular, the situation regarding reduction of in-situ CTD observations. The Practical Salinity Scale 1978 is an attempt to remove the shortcomings; it has been recommended for international acceptance. The basis for this new scale is an equation relating the ratio of the electrical conductivity of the seawater sample to that of a standard potassium chloride solution (KCI) at15deg C atmospheric pressure. The samples used were prepared from standard seawater diluted with distilled water or evaporated by weight. Finally, the set of new equations for CTD data reduction is given, based upon the work of authors whose papers are appearing elsewhere in this volume. 相似文献
2.
The VOF method and the k–ε model, combined with the equation of state of air at constant temperature, have been used to calculate the total horizontal wave force caused by monochromatic waves acting on a perforated caisson with a top cover. From comparison of various parameters, such as the total horizontal force, the pressure difference on the front wall, the pressure on the back wall and the pressure on the top cover, between the numerical results and test data, it can be seen that the numerical results agree well with the test data. It is concluded that the method described in this paper can be utilized to calculate wave forces acting on perforated caissons with a top cover in the case of nonovertopping, nonbreaking waves. A simplified method to calculate the total horizontal force has been developed, based on test data, using a least-squares method. A comparison between the numerical results and the values calculated from the simplified equations shows good agreement. Therefore the simplified equations can be used in engineering applications to evaluate the total horizontal force on a perforated caisson with a top cover. 相似文献
3.
In the first part of our studies, the unified solutions of existing waves have been obtained by using the linear wave equations without making the assumptions of irrotation and hydrostatic pressure. In this paper, the second part of our studies, we shall devote to linear long wave equations without the assumption of hydrostatic pressure. All the solutions in the case of ω=f are found. A set of solutions is also obtained, with a similarity to the unified solutions of the Sverdrup waves and the Poincare waves, but the corresponding waves represented by such a set have a different vertical structure of velocities. The set is not included in the solutions of linear long wave equations under the assumption of hydrostatic pressure and, therefore, is regarded as possible waves filtered out by the assumption of hydrostatic pressure. 相似文献
4.
A numerical model for the simulation of typhoon surge has been developed for the coastal areas of the northern Taiwan. Results from the model outputs are then used as a typhoon surge data bank for 7 main estuary areas in this region. The data bank consists of the historical typhoon events from 1980 to 2004. Both characteristic and frequency analyses of the typhoon surge in the coastal region have been studied. Using these data, a relation between the surge height and pressure distribution is obtained. It is shown that, either the numerical model, or the statistical equations presented in this paper, can be used to predict possible surge heights in the estuary areas with sufficient accuracy. 相似文献
5.
CTD是测量海水温度、电导率和压力的仪器,在海洋科学考察、海洋资源调查开发、海洋环境监测预报和海洋军事研究中应用广泛。SZC15-4型多参数CTD是国产SZC15系列CTD最新型号,用于测量海水的温度、电导率、深度和叶绿素浓度,适用于近岸海洋调查。文中介绍了SZC15-4型多参数CTD剖面仪的性能、工作原理、系统组成和工作流程。并通过海上试验,与SBE19CTD在相同环境条件、相同采样速率下作比测,通过对实验数据做相关运算得出SZC15-4型CTD与SBE19在温度、盐度相关性优于0.999 9,表明两种仪器具有很高的相关特性。 相似文献
6.
A Vertical Two-Dimensional Model to Simulate Tidal Hydrodynamics in A Branched Estuary 总被引：1，自引：1，他引：1
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. 相似文献
7.
采用熔体旋甩法结合放电等离子烧结技术(MS-SPS)制备了p型填充式方钴矿化合物Ce0.3Fe1.5Co2.5Sb12,研究了熔体旋甩工艺对微结构以及热电性能的影响规律.结果表明,较高的铜辊转速和较低的喷气压力有利于提高熔体的冷却速率,使带状产物晶粒细化.薄带经SPS烧结后得到致密、基本单相、晶粒尺寸均匀细小(150—300 nm)的块体.与传统方法制备的试样相比,MS-SPS试样虽然电导率有所降低,但因具有较大的Se 相似文献
8.
The practical (Sp) and reference (SR) salinities do not account for variations in physical properties such as density and enthalpy. Trace and minor components of seawater, such as nutrients or inorganic carbon affect these properties. This limitation has been recognized and several studies have been made to estimate the effect of these compositional changes on the conductivity–density relationship. These studies have been limited in number and geographic scope. Here, we combine the measurements of previous studies with new measurements for a total of 2857 conductivity–density measurements, covering all of the world׳s major oceans, to derive empirical equations for the effect of silica and total alkalinity on the density and absolute salinity of the global oceans and to recommend an equation applicable to most of the world׳s oceans. The potential impact on salinity as a result of uptake of anthropogenic CO2 is also discussed. 相似文献
9.
热带气旋气候数学模型的预报应用 总被引：5，自引：2，他引：3
使用西太平洋海温格点资料,选取若干个因子,组成多个复合因子,建立权重方程,使得单因子的相关系数信度检验0．05提高到复合因子的信度检验0．01,权重方程的信度检验提高到0．001。用权重方程产生的突变的高阶非线性预报方程,其Y与X的相关系数比1阶线性方程提高5％左右。自1999年至今,热带气旋年、月频数气候预测的模型投入到实际预报应用,其预报准确律达到75%～90％。使用非线性预报模型作了逐日气压、逐日雨量的气候预测。将沿海气压场、雨量场的气候预测结果用于分析、制作热带气旋登陆中国以及广东地区的时段、地段的气候预报,准确率达80％～90％。 相似文献
10.
The conductivity ratio of diluted and concentrated standard seawater has been measured very accurately in a salinity range from 0 to42permil and at temperature from -1 to30deg C. All the data have been fitted into polynomials which are compared with previous data. The specific conductance of seawater is deduced and a polynomial for the full range of salinity and temperature is proposed. Data presented in this paper have been used, with those of Dauphinee presented in this issue, to elaborate the new "Practical Salinity Scale 1978." 相似文献
11.
为满足水下滑翔器连续获取海洋剖面水文动力高质量数据的应用需求,利用自主研制的电磁感应式电导率传感器,集成快速响应的热敏电阻与压力传感器,以PIC18F2520单片机为电路系统的核心控制器,设计出一种适用于水下滑翔器搭载的微型化、低功耗、重量轻的SZQ1-1新型CTD传感器。该CTD测量仪经实验室多次标定,数据质量达到海试要求。2016年10月,该CTD传感器与海鸟SBE19 Plus在青岛胶州湾进行了海试比测。海试结果证明,该CTD传感器与SBE19 Plus测量结果相近,实时获取的温、盐、深剖面数据精度满足水下滑翔器的搭载要求。 相似文献
12.
On transformation of the near-surface atmospheric boundary layer in the ocean temperature front area
A two-dimensional, quasi-analytical model for the formation of the internal atmospheric boundary layer in the ocean temperature front area is described, developed on the basis of integral relations for motion and thermal conductivity equations. The computed data are matched with wind speed observations, as well as with direct and indirect dynamic velocity measurements in the air, obtained across the Gulf Stream frontal zone.Translated by V. Puchkin. 相似文献
13.
走航式海洋多参数剖面测量系统(MVP)是一种集成程度和自动化程度都较高的海洋调查设备,能对多要素进行同时观测,获得高水平空间分辨率的数据资料。MVP由于温度和电导率传感器响应时间的不匹配,下放速度过快(峰值速度4m/s)而造成非常严重的盐度尖峰现象。本研究通过结合F法、GM法和Grose法提出的盐度尖峰订正方案,提出了一种新的方法Match conductivity and temperature response times法,对压力、温度和电导率传感器三者进行响应时间的匹配来减弱盐度尖峰。与SBE-9型CTD资料进行对比发现订正后的资料误差比订正前减小80%,与CTD盐度曲线互相关程度为0.917。对比35N断面修正前后的盐度资料发现订正后温盐跃层处出现的低盐区域消失,与CTD断面资料对比结果显示MVP资料比CTD资料在细结构上更具有优势。 相似文献
14.
Numerical study for waves propagating over a porous seabed around a submerged permeable breakwater: PORO-WSSI II model 总被引：1，自引：0，他引：1
The phenomenon of the wave, seabed and structure interactions has attracted great attentions from coastal geotechnical engineers in recent years. Most previous investigations have based on individual approaches, which focused on either flow region or seabed domain. In this study, an integrated model (PORO-WSSI II), based on the Volume-Averaged/Reynolds-Averaged Navier-Stokes (VARANS) equations and Biot's poro-elastic theory, is developed to investigate the mechanism of the wave-permeable structure-porous seabed interactions. The new model is verified with the previous experimental data. Based on the present model, parametric studies have been carried out to investigate the influences of wave, soil and structure parameters on the wave-induced pore pressure. Numerical results indicated: (i) longer wave period and larger wave height will obviously induce a higher magnitude of pore pressure at the leading edge of a breakwater; (ii) after a full wave-structure interaction, the magnitude of pore pressure below the lee side of a breakwater decreases with an increasing structure porosity while it varies dramatically with a change of structure height; and (iii) the seabed thickness, soil permeability and the degree of saturation can also significantly affect the dynamic soil behaviour. 相似文献
15.
In the present study,a semi-implicit finite difference model for non-bydrostatic,free-surface flows is analyzed and discussed.The governing equations are the three-dimensional free-surface Reynolds-averaged Navier-Stokes equations defined on a general,irregular domain of arbitrary scale.At outflow,a combination of a sponge layer technique and a radiation boundary condition is applied to minimize wave reflection.The equations are solved with the fractional step method where the hydrostatic pressure component is determined first,while the non-hydrostatic component of the pressure is computed from the pressure Poisson equation in which the coefficient matrix is positive definite and symmetric.The advectiou and horizontal viscosity terms are discretized by use of a semi-Lagrangian approach.The resulting model is computationally efficient and unrestricted to the CFL condition.The developed model is verified against analytical solutions and experimental data,with excellent agreement. 相似文献
16.
Measurements of full-scale wave impact pressures on seawalls have been made over a period of four years, up to and including the winter of 1980/1981, on seawalls in the South and West of England. This investigation is the first of its kind to be carried out in the U.K. using modern measuring and recording techniques and has produced significantly more wave impact pressure data than all previous full-scale investigations.Poor correlation was found between the semi-empirical equations at present used to estimate wave impact pressures and the prototype data obtained during this investigation. A rational expression for the estimation of wave impact pressures on coastal structures has thus been derived based on the local wave parameters at impact and includes a coefficient related to the percentage of air entrained in the incident wave. 相似文献
17.
Vikram Singh 《Marine Georesources & Geotechnology》2018,36(5):505-514
Although the uplift behavior of offshore plate anchors under undrained conditions has been investigated well in the past, studies on the behavior of anchors under long-term sustained loading are in relatively few numbers. The time required for consolidation under sustained load is important because the shear strength of soil changes after dissipation of excess pore pressure. In this paper, small strain finite-element analyses have been performed to investigate the consolidation time history above and beneath strip anchors. The modified cam clay plasticity constitutive model is used for modeling coupled pore fluid stress analysis. The effects of magnitude of preloading with embedment level have been studied. As expected, the FE results have shown that excess pore pressure dissipation time for soil above the anchor increased with the increase in embedment depth and the magnitude of preload. Rapid dissipation of negative excess pore pressure beneath the anchor was observed with increasing embedment depth, if the preload magnitude is equal to or more than 60% of the undrained capacity. Observed consolidation responses are presented as nondimensional design charts and simplified equations for ease of practice. 相似文献
18.
A seabed instrument called Lancelot has been developed to measure pore pressure characteristics within potentially unstable marine sediment deposits, in any water depth. An estimate of the coefficient of consolidation can be obtained from the sediment pore pressure dissipation response that occurs following penetration into the seabed. This data can be used to calculate the coefficient of hydraulic conductivity, which is useful in analyzing the seepage velocity of pore fluids moving within the sediment mass. Pore-water pressures in excess of the normal hydrostatic profile are detected and used in static and dynamic liquefaction analyses, with a view toward understanding the origin of unusual seabed features such as pockmarks, as well as short-term instability caused by wave loading. An example of static liquefaction due to seepage stress is given for sites in and adjacent to the well-known 1929 Grand Banks debris flow, along with an example of incomplete liquefaction caused by dynamic wave loading within Miramichi Inner Harbor, New Brunswick. The adoption of in situ measurement techniques is shown to produce data of a quality not normally obtainable from recovered core samples, due to pressure relief and sampling disturbance effects. 相似文献
19.
Laboratory equipment has been built which will measure the permeability and thermal conductivity of deep-sea sediments at their in-situ conditions of hydrostatic pressure, temperature, and void ratio. The apparatus has the capability of uniaxially consolidating a sediment sample to simulate compaction within the sediment column, while exposing the specimen to hydrostatic pressures ranging from atmospheric to 62 MPa and to temperatures from 22 to 220°C. The equipment includes a hypodermic needle mounted vertically through the base of the pressure vessel from which thermal conductivity is determined by the needle probe method. The system also features a combination of dead-weight testers which produces a small hydraulic gradient across the sample and permits the measurement of sediment permeability at large hydrostatic pressures.The physical property data generated from this apparatus will be important in understanding the mechanisms of heat transfer through the ocean floor and in analysing the coupled flow of heat and pore fluid in the vicinity of a heat source, such as a radioactive waste canister, buried in the seabed. 相似文献
20.
应用经CSPM法和黎曼解修正后的光滑粒子流体动力学(SPH)方法,建立了主动吸收无反射数值波浪水槽,研究波浪作用下多孔介质结构的水动力特性。流体运动控制方程采用N-S方程,多孔渗水结构内流体的运动控制方程考虑渗流力的影响。数值计算结果给出了水槽内不同位置测点的波面历时曲线和越浪量随时间变化曲线,并同试验结果和Philip Liu的数值计算结果进行了比较。并对一个波浪周期内斜坡堤多孔介质结构内外的速度场和压力分布进行了讨论分析。计算分析表明,数值计算波面较Philip Liu的计算结果与试验结果吻合更好。说明应用SPH方法建立的二维数学模型能够较好地模拟破碎波在多孔渗水斜坡上的爬坡和越浪。 相似文献