A Nonlinear Model of Surf Beat

A nonlinear short-wave-averaged (surf beat) model is presented. The model is based on that of Roelvink (1993), but the numerical techniques used in the solution are based on the so-called weighted-averaged flux (WAF) method (eg Watson et al., 1992), with time-operator splitting used for the treatment of some of the source terms. This method allows a small number of computational points to be used, and is particularly efficient in modelling breaking long waves. The short-wave (or primary-wave) energy equation is solved using a more traditional Lax-Wendroff technique. Results of validation indicate that the model performs satisfactorily in most respects.     

辽宁西部八家子多金属矿田控矿构造型式

本文分析了八家子多金属矿田的地质构造特征,提出该区的构造型式为一个滑脱—逆冲推覆构造。它是在北西问南东方向的侧向挤压作用下,由八家子附近的中上元古界与古生界地质块体,沿着与基底花岗岩的界面自北西向南东滑移造成的。主要表现特征是:在前缘形成了呈铲式的收缩型滑脱断层、逆冲断层等挤压性构造,在后缘则出现张裂带并陷落成盆地,两侧发育具有转换断层性质的走滑断层。逆冲断层及边界走精断层是区内主要控矿构造。八家子滑脱—逆冲推覆构造的主要活动时期为三叠纪晚期,结束于早侏罗世。     

Red-light districts and Toleration Zones: geographies of female street prostitution in England and Wales

Summary Although female street prostitution is widely acknowledged to occur in specific spaces, characteristically referred to as 'red-light' districts, geographers have been remarkably reticent in examining the nature and location of these spaces. Against a backdrop of mounting debate surrounding the legal status of prostitution in England and Wales, this paper considers the importance of such areas in the regulation and containment of street prostitution, and speculates as to how changing social and legal attitudes might result in very different geographies of prostitution.     

Wave Reflection Coefficient Spectrum

1 .IntroductionWavereflectionfromstructuresisanimportantfactorforthedesignofthestructures .Therehavebeenmanyresearchesonwavereflectionwithregularwavesandmonochromaticirregularwaves .Miche( 1 951 )proposedanon dimensionalMichenumberMfornormallyincidentirregularwavesconsideringwavebreakingbecauseofthedeepeningofwavesteepnessontheslopeofbreakwaters .ThereflectioncoefficientisproportionaltoM ,i.e .,Kr ∝M =4g( 2π) 5/ 2tan5/ 2 α(Hsf2p) ( 1 )wheregisthegravitationalacceleration ,Hsthesignifican…     

Relativistic Information Entropy on Uncertainty Analysis

- in this paper, a new approach to relativistic information entropy is used to assess some relative uncertainties in structural reliability assessment. This approach is composed of the information theory and the relativistic theory, and can be used to measure the relativity of parameter uncertainty and system uncertainty in structural reliability theory based on the same generalized relativistic reference system. Therefore, the structural reliability assessment can be assessed reasonably by the approach.     

Behavior of Deformation and Strength of Concrete Under Biaxial Stresses

The study of the behavior of concrete under biaxial stresses is essential to the design of offshore concrete platforms. Using the multiaxial test apparatus developed by the authors, the deformation and strength of concrete under biaxial stresses are studied experimentally. Based on the test data, an endochronic damage constitutive model and a failure criterion are proposed. According to the above model, an incremental nonlinear iterative programme is developed, and a plate sample in plane stress state is analyzed.     

Vertical 2D Modeling of Free Surface Flow with Hydrodynamic Pressure Using SIMPLE Arithmetic in σ Coordinates

A numerical model for shallow water flow has been developed based on the unsteady Reynolds-averaged Navier-Stokes equations with the hydrodynamic pressure instead of hydrostatic pressure assumption. The equations arc transformed into the a-coordinate system and the eddy viscosity is calculated with the standard k -ε turbulence model. The control volume method is used to discrete the equations, and the boundary conditions at the bed for shallow water models only include vertical diffusion terms expressed with wall functions. And the semi-implicit methed for pressure linked equation arithmetic is adopted to solve the equations. The model is applied to the 2D vertical plane flow of a current over two steep-sided trenches for which experiment data are available for comparison and good agreement is obtained. And the model is used to predicting the flow in a channel with a steep-sided submerged breakwater at the bottom, and the streamline is drawn.     

Long-Term Joint Distribution of One-Tenth Large (or Significant) Wave Height with Average Period

- In this paper, by using the wave data from a few oceanographic observation stations in the coastal zone of the Yellow Sea, the East China Sea and the South China Sea, the long-term joint distribution of the one-tenth large (or significant) wave height with average period is studied. The statistical data demonstrate that the long- term distribution of the one- tenth wave height or average period fits the log-normal distribution, thus the joint distribution also fits the two-dimensional log-normal distribution. Then the conditional probability distribution of the average period is derived, and the range as well as the mode of the average wave period corresponding to a certain return period of wave height can be calculated easily.     

Redundancy Measure and Its Application to the Design and Maintenance of Marine Structures

This paper is a survey of the state-of-the-art knowledge in structural redundancy measure andits application.The existing deterministic and probabilistic measures of structural redundancy are summa-rized.Emphasis is given to the discussion of their advantages and limitations.The application of damagetolerance concept in the design and maintenance of marine structures is also reviewed.Some most criticalproblems in structural redundancy are proposed for future research.     

Comparisons of Computational and Experimental Results of Solitary Wave Breaking

- In this paper, the solitary wave deformation along a gentle slope and the impact pressure, on the wall are investigated experimentally and the results are compared with numerical results obtained based on the volume of fluid (VOF) method. The topography used in the experiment consists of three segments. The left segment is a 1:4 slope, the middle segment 1 :SO slope and the right segment a horizontal bed. Both the wave heights and breaking points obtained from numerical simulation and experiments are in good agreement. Numerical results give reasonable pressure distributions of breaking waves on the wall.