Search results for "Ocean"
showing 10 items of 2919 documents
Improving and enhancing NWP based wind power forecasts under Norwegian conditions
2015
Doktorgradsavhandling i ingeniørvitenskap, Universitetet i Agder, 2015 This thesis studies methods for improving and enhancing NWP based wind power forecasts for cases from the Western coast of Norway. This is an area with excellent wind conditions, but where the installed wind power capacity at present is limited. The area is characterized by a rugged coastline and complex terrain, which have earlier been shown to lead to high wind power forecast errors. The overall aim of the thesis is to study how this kind of conditions influence wind power forecast errors and to investigate how wind power forecast models can be made more resistant to the challenges these conditions pose. The data basis…
Nonlinear air dynamics of a surface effect ship in small-amplitude waves
2022
In many existing works, the seakeeping motions and air dynamics of a surface effect ship (SES) were assumed to be linear under small-amplitude waves (wave amplitude to wave length ratio ≤ 5%) to enhance the computational efficiency. However, according to SES model test results, it was found that even in small-amplitude waves, the fluctuating air cushion pressure shows significantly nonlinear effects. To precisely reveal this distinctive feature, the origin of nonlinearity was carefully investigated and the air leakage was considered as the main source of nonlinearity based on mathematical analysis in this paper. The reason is that the variance of clearance height under seals is comparable t…
Analysis of spar and semi-submersible floating wind concepts with respect to human exposure to motion during maintenance operations
2022
Floating offshore wind turbines (FOWTs) are expected to experience onsite maintenances and inspections during their lifetimes. To carry out offshore maintenance activities, a crew will be transferred to an FOWT and spend several hours on board. A challenge may arise if the motions of a floating platform affect the crew's comfort level and further jeopardise their work performance or even health. To address this challenge, this paper analyses the motion characteristics and dynamic properties of a spar and two semi-submersible FOWTs, all exhibiting very different motion characteristics. The impact of the platform motions and accelerations on the workability of the FOWTs are investigated. We c…
Extended Environmental Contour Methods for Long-Term Extreme Response Analysis of Offshore Wind Turbines
2020
Author's accepted manuscript. Environmental contour method is an efficient method for predicting the long-term extreme response of offshore structures. The traditional environmental contour is obtained using the joint distribution of mean wind speed, significant wave height, and spectral peak period. To improve the accuracy of traditional environmental contour method, a modified method was proposed considering the non-monotonic aerodynamic behavior of offshore wind turbines. Still, the modified method assumes constant wind turbulence intensity. In this paper, we extend the existing environmental contour methods by considering the wind turbulence intensity as a stochastic variable. The 50-ye…
BUSINESS VALUE CREATED BY MANAGEMENT ACCOUNTING
2018
Porter stated in his value chain concept that business support activities are contributing to the value creation process of a business organization. In the “classical view” business support activities are considered as indirect productive and not having a clear and direct contribution to the business organization value chain. The information age has enabled and leveraged business support activities to become decisive contributors to the value creation process of any business. Can this value contribution be somehow determined or quantified? Management accounting is a classical business support activity that contributes to the business organization value chain. Through usage of value manageme…
AN EMPIRICAL VIEW ON VALUE THEORY AND VALUE-BASED MANAGEMENT
2016
The main economic purpose of a business organization is to create value for its owner. The value concept is a complex notion that has developed alongside human history and reflects the concerns of human society through time. As a result of the value theory, the management of value has also emerged as an essential and accompanying activity. Value-based management emerged as a management philosophy rather than a management method. It consists of a change in mindset from managing resources or output quantities to value creation. The challenge is to identify or create the value flows and act upon these within the specific business organization to have proper value management. Value creation and…
Macro-elements in the mixed boundary value problems
2000
The symmetric Galerkin boundary element method (SGBEM), applied to elastostatic problems, is employed in defining a model with BE macro-elements. The model is governed by symmetric operators and it is characterized by a small number of independent variables upon the interface between the macro-elements.
Sun-induced chlorophyll fluorescence II: Review of passive measurement setups, protocols, and their application at the leaf to canopy level
2019
Imaging and non-imaging spectroscopy employed in the field and from aircraft is frequently used to assess biochemical, structural, and functional plant traits, as well as their dynamics in an environmental matrix. With the increasing availability of high-resolution spectroradiometers, it has become feasible to measure fine spectral features, such as those needed to estimate sun-induced chlorophyll fluorescence (F), which is a signal related to the photosynthetic process of plants. The measurement of F requires highly accurate and precise radiance measurements in combination with very sophisticated measurement protocols. Additionally, because F has a highly dynamic nature (compared with othe…
Temporal dynamic of biofilms enhances the settlement of the central-Mediterranean reef-builder Dendropoma cristatum (Biondi, 1859).
2021
Abstract Research on marine invertebrate settlement provides baseline knowledge for restoration technique implementation, especially for biogenic engineers with limited dispersion ability. Previously, we determined that the maturity of a biofilm strongly enhances the settlement of the vermetid reef-builder Dendropoma cristatum. To elucidate settlement-related biofilm features, here we analyse the structure and composition of marine biofilms over time, through microscopic observations, eukaryotic and prokaryotic fingerprinting analyses and 16S rDNA Illumina sequencing. The vermetid settlement temporal increase matched with the higher biofilm coverage on the substratum and the reduction of th…
Regionalizing rainfall at very high resolution over la Réunion island using a regional climate model.
2014
Abstract Regional climate models (RCMs) should be evaluated with respect to their ability to downscale large-scale climate information to the local scales, which are sometimes strongly modulated by surface conditions. This is the case for La Réunion (southwest Indian Ocean) because of its island context and its complex topography. Large-scale atmospheric configurations such as tropical cyclones (TCs) may have an amplifying effect on local rainfall patterns that only a very high-resolution RCM, forced by the large scales and resolving finescale processes, may simulate properly. This paper documents the capability of the Weather Research and Forecasting Model (WRF) RCM to regionalize rainfall…