Abstract In this paper, we proposed a three-dimensional model for the tension analysis of submarine power cables during laying operations. Both flexural rigidity and axial elasticity were taken into consideration in the form of classical Euler-Bernoulli beam element theory. The governing equations were numerically solved by fourth-order Runge-Kutta methods and the derivatives of the curvature with respect to the cable element arc length can be approximately expressed by the finite difference method. Numerical examples were illustrated to study the influence of some key parameters on the cables and some significant conclusions are drawn.

ABSTRACT: This paper analyses the trends and the future projections of significant wave height in several ocean areas at different parts of the world. It uses a stochastic Bayesian hierarchical space-time model, with a regression component with atmospheric levels of CO2 as covariates in order to estimate the expected long-term trends and make future projections towards the year 2100. The model was initially developed for an area in the North Atlantic ocean, and has been found to perform reasonably well there, and it is now investigated how the model performs for other ocean areas. 11 new ocean areas have been analysed with the model, and this paper presents the results pertaining to the estimated long-term trends and future projections of monthly maximum significant wave height for each of the 12 ocean areas. INTRODUCTION The ocean wave climate is obviously important to maritime safety, as well as many other areas of society. Ships and other marine and coastal structures are designed in order to withstand normal and extreme environmental loads imposed by the forces of wind and waves at sea. However, the potential impact of climate change on the ocean wave climate is often neglected, and it is also a lack of knowledge on how the future ocean wave climate will change as a result of climate change. Recently, a Bayesian hierarchical space-time model was developed to investigate long-term trends and make future projections of the ocean wave climate for an area in the North Atlantic ocean. Results from the initial model are reported in Vanem et al. (2012a), results from a revised model with a logarithmic transformation of the data are reported in Vanem et al. (2012b) and results from an extended model with a regression component on atmospheric levels of CO2 are reported in Vanem et al. (2012c).

ABATRACT: In this paper we propose a projection based observer that can be used to estimate state vectors such as position and velocity for its motion control using non-uniform interval multi-sensor outputs. The output measurement we will use in estimating the state is a series of known multi-sensor asynchronous outputs. The idea for the proposed projection based observer is that each measurement output give us a piece of information which we can use to project the state vector onto the null space of C (output matrix) in order to reduce the error of state estimation. We will explain how to construct the projection operator in a Hilbert space and show the noise rejection of this algorithm by using Lyapunov method. The applicability of the proposed based observer to SAUV (semi-Autonomous Underwater Vehicles) navigation system is demonstrated through computational analysis with theoretical data. Its comparison with traditional Kalman filtering is assessed for computer simulations of the KRISO SAUV and experiments of the FAU Ocean Voyager II Autonomous Underwater Vehicle. INTRODUCTION There are numerous applications where the usage of an Autonomous Underwater Vehicle is desired. Born from the military requirements for stand-off weapons, remote sensing, mine field mapping and clearance, and coupled with the rapid commercialization of microcomputer technology, it is now possible to foresee some civilian use for AUVs in ocean science, offshore operations, environmental monitoring and underwater inspection. One continuing issue is the precise navigation of such vehicles underwater. While differential GPS (DGPS) is widely used for survey ships and underwater vehicle while surfaced, the navigation problem underwater requires the fusion of data from sensors such as Doppler sonar in a ground locked mode, compass data (a three axis magnetometer), acoustic systems like a SSBL and low cost inertial units.