Showing papers in "Ocean Engineering in 1999"

TL;DR: In this paper, a theoretical model is developed to simulate the energy conversion from wave to turbine shaft of an oscillating-water-column (OWC) plant equipped with a Wells air-turbine and with a valve (in series or in parallel with the turbine) for air-flow control.

TL;DR: In this paper, an analytical model of dry suit systems, both conventional and those containing Comfortemp materials, is developed to predict their thermal performances in simulated ocean environments, and to assess the relative thermal performances of candidate Comfortemp foams, including those interspersed with different weight percentages of micro-encapsulated PCMs, in an effort to maximize thermal storage capabilities.

TL;DR: In this article, an attempt has been made to delineate the rupture surfaces of anchors embedded in submerged and dry sand beds at various depths, and the results exhibited two different modes of failure depending on the embedment ratio, namely, shallow and deep anchor behaviour.

TL;DR: In this paper, the authors studied reactive control of wave energy devices in irregular waves and showed that reactive control is not optimal, but would enhance efficiency at low peak frequencies where energy-rich swells predominate, and allow significantly smaller devices to fulfill a given power requirement.

TL;DR: In this article, the effects of axial preloading on the dynamic properties of cylindrical members, the extent of damage and propagation of dynamic instability in the tubular members have also been investigated.

TL;DR: In this paper, the steady rolling response in a regular beam sea of a 1 : 50 scale model of a destroyer in the bare hull condition has been studied, and the experimental evidence of bifurcations with jump in amplitude and phase during the tests at two different wave frequencies.

TL;DR: In this paper, a third transformation is proposed, which combines the better features of the two earlier ones and which is appropriate for simulation work, which is demonstrated with an example of a series from Figueira da Foz, a location of the Portuguese Coast.

TL;DR: In this article, a new form of Boussinesq-type equations accurate to the third order are derived to improve the linear dispersion and nonlinearity characteristics in deeper water.

TL;DR: In this article, the influence of stern shape on the parametric stability of fishing vessels is studied, both analytically and experimentally, and the analytical method takes into consideration the effects of the heave and pitch motions and wave passage and shows good agreement with experimental results.

TL;DR: In this paper, the long-term distribution of significant wave height with the Gamma, Beta and second kind models is modeled as a maximum likelihood estimation problem, and three different tail types of Extreme Value Theory are used simultaneously as a means of assessing the uncertainty effects that result from choosing equally plausible models with different tails.

TL;DR: A numerical time-simulation algorithm for analysing highly nonlinear solitary waves interacting with plane gentle and steep slopes is described by employing a mixed Eulerian-Lagrangian method.

TL;DR: Transformations are developed for applying the advanced methods and working with directional wave information stored in the WMO's FM 65 WAVEOB code, the FWGP's Wave Data Analysis Standard (WDAS) format, and similar codes and formats.

TL;DR: In this article, a three-layered neural network whose units of input layer are h/L, H/h, d/h and BM/h was employed to predict whether impact wave force will act on the upright section of a composite breakwater.

TL;DR: In this article, the generalized Krylov-Bogoliubov asymptotic method was used to model the nonlinear roll motion of a ship under the influence of a sinusoidal exciting force.

TL;DR: In this paper, perforated hollow piles in two rows were conducted in a two dimensional wave flume and the influence of water depth, incident wave steepness, clear spacing between the piles and the spacing of pile rows on transmission coefficient have been studied.

TL;DR: In this paper, the dynamic stability of the heave motion of marine cable-body systems operating in alternating taut-slack conditions is considered, based upon a single-degree-of-freedom model.

TL;DR: In this article, a set of Boussinesq equations were used to study the transformation of waves before, during and after wave breaking provided the bed slope is relatively gentle, and the ability of the developed model to compute wave-induced setdown and setup of regular waves propagating onto a submerged coral reef consisting of relatively steeper slopes.

TL;DR: In this article, simple prediction methods are proposed to estimate the wave induced pressures on smooth impermeable seawalls based on the physics of the wave structure interaction, the sloped seawall is divided into a total of five zones (zones 1, 2 and 3 during run-up and zones 4 and 5 during rundown) and the negative wave pressures are due to partial reflection and phase shift effects.

TL;DR: In this paper, the uncertainty of some commonly used spectral wave parameters resulting from the spectral estimation procedure is assessed and it is observed that the methods of spectral estimation produce a significant uncertainty for all parameters examined, but this is of considerable importance only for the peak period, which is one of the most important parameters to model the wave climate.

TL;DR: This work shows how to calculate the encountered wave period distribution for a ship traveling with constant speed on a Gaussian random sea with a directionally distributed frequency spectrum.

TL;DR: In this article, a set of Boussinesq-type equations with improved linear frequency dispersion characteristics in deeper water is proposed to simulate the transformation of waves before, during and after wave breaking.

TL;DR: In this paper, a potential flow-based time domain panel method was formulated to predict the performance of a lunate and rectangular planform in large amplitude, unsteady motion, and the results showed that the lunate tail gave higher propulsive efficiency than the rectangular tail.

TL;DR: In this paper, the authors provided a detailed analysis for the second-order diffraction of monochromatic waves and proposed a forward prediction method for computing the integration on the free surface.

TL;DR: In this article, the authors present an analytical solution for the dynamic behavior of both the platform and tethers in the tension leg platform system when the platform system is subjected to the wave-induced surge motion and the flow-induced drag motion.

TL;DR: In this article, model tests were performed on a shallow water breakwater concept of this type to determine the reflection and transmission coefficients, and it was found that the breakwater design was effective at certain wave characteristics.

TL;DR: In this article, the surface drift of an inextensible film due to a series of progressive gravity waves is investigated both analytically and experimentally, and a second approximation of the conformal mapping that transforms the progressive sinusoidal surface to the horizontal axis is applied, thus allowing the analysis to formally accommodate a boundary layer thickness that is much less than the wave height.

TL;DR: In this paper, a closed-form solution is presented for any eddy viscosity which is separable in time and space, allowing for the derivation of an analytic expression for the temporal and vertical structure of the cross-shore velocity under an arbitrary wave field.

TL;DR: The boundary integral element method based on Green's formula is applied to the analysis of transient flow problem in corrugated bottom tanks as discussed by the authors, which is formulated as a two-dimensional linear, initial boundary value problem in terms of a velocity potential.

TL;DR: In this article, the authors report on a theoretical and an experimental study into the collapse of three thick-walled circular conical shells, which were tested to failure under external hydrostatic pressure.

TL;DR: This paper summarizes experimental results of the testing of composite panels stiffened with preform frames under in-plane uniaxial compressive loads and shows promise in the reduction of fabrication costs for large ship construction.