Browsing NTNU Open by Author "Leira, Bernt Johan"
Now showing items 1-20 of 152
-
A comparative study of the stochastic averaging method and the path integration method for nonlinear ship roll motion in random beam seas
Chai, Wei; Dostal, Leo; Næss, Arvid; Leira, Bernt Johan (Journal article; Peer reviewed, 2017)In this paper, the energy-based stochastic averaging method and the path integration method are applied to study the stochastic response of the nonlinear roll motion in random beam seas. Specifically, the Markov diffusion ... -
A global assessment of a floating bridges ability to withstand a ship collision
Jansen, Kristin Victoria (Master thesis, 2016)It is planned to exchange the ferry connections along the western coast of Norway with fixed road connections. To be able to do this, new concepts for fjord crossings have to be used. One of these alternatives is a floating ... -
A new combination of conditional environmental distributions
Horn, Jan-Tore H.; Bitner-Gregersen, Elzbieta M.; Krokstad, Jørgen R; Leira, Bernt Johan; Amdahl, Jørgen (Journal article, 2018)In this paper, a joint distribution of all relevant environmental parameters used in design of offshore structures including directional components is presented, along with a novel procedure for dependency modelling between ... -
Adaptive identification of lowpass filter cutoff frequency for online vessel model tuning
Han, Xu; Ren, Zhengru; Leira, Bernt Johan; Sævik, Svein (Peer reviewed; Journal article, 2021)Tuning of vessel models in real-time based on vessel measurements and weather information is of great interest in order to increase the safety and efficiency of marine operations. Vessel motion signals usually contain ... -
Analyse av mulige løsninger for stigerør og overflatefartøy for undervannsborerigg
Andersen, Anders Horvei (Master thesis, 2013)AbstractThis study gives an overview of the challenges that comes when petroleum activities is moving further north into an arctic environment. The arctic has new challenges, as cold hard weather, snow and ice. The marine ... -
Analyse av stigerørs-indusert belastninger på brønnhode for boring- og produksjonsfasen
Lian, Kjell Ivar (Master thesis, 2019)Utmatting av undervanns brønnhoder er et voksende problem i offshore industrien. Store krefter blir overført fra stigerørssytemet og ned til brønnhodet som forårsaker utmatting, og levetiden til en brønn øker som et resultat ... -
Analyses of Two Ice Class Rules - for The Design Process of a Container Ship
Su, Yixiang (Master thesis, 2017)The Finnish-Swedish Ice Class Rules (FSICR) has a long history. Having being tested by countless ships, it becomes the authority in Baltic Sea region. International Association of Classification Societies Polar Class (IACS ... -
Analysing the effect of hull vibration due to main engine and propeller excitation on fatigue crack growth of pipe stack support using FEA
Kleivane, Siri Kolle (Master thesis, 2021)Vibrasjons problemer i skip er et like aktuelt tema i dag som tidligere. Vibrasjoner kan forårsake lokal skade og kan lede til utmattings sprekkvekst, spesielt for sveiste komponenter. De vanligste vibrasjons kildene er ... -
Analysis of Explosion Load Effects in Pipe-racks: Explosion simulation and its respective structural response on pipe-racks on a offshore topside module
Su, Aiwei (Master thesis, 2012)An explosion on a typical offshore installation is a critical, however rare accidental event which may result in damage and loss of property, and in the worse case loss of lives. Top-side sections on an offshore installation ... -
Analysis of Hull Structure Response for a Sevan Arctic Mobile Drilling Unit in Arctic Areas subjected to Ice Loading
Haugen, Ine (Master thesis, 2014)The interest for Arctic deep water development intensifies as the worldwide demand for oil and gas continues to grow. As much as 25 % of the world s remaining hydrocarbons are assumed to be located in the Arctic area. ... -
Analysis of Riser Loads during BOP sailing.
Søgnesand, Sigmund Anders Isaac (Master thesis, 2015)Transferring a drilling rig and its subsea equipment from one location to another by conventional means tends to be time consuming. With low oil prices and increasing rig rates, operators are looking into making drilling ... -
Analysis of Riser-induced Loading on Wellhead
Lylund, André (Master thesis, 2015)When riser systems are connected to subsea wells, large forces and moments are transmitted to the wellheads. This is due to the large weight of the blowout preventer and the environmental excitation forces that are transmitted ... -
Analysis of the Hull Structure of Sevan Arctic Mobile Offshore Drilling Unit subjected to accidental Ice Loads
Bratlie, Patrick (Master thesis, 2015)Due to an increasing energy demand in the world, the interest of the Arctic region related to offshore oil and gas exploration is increasing. The demand of structures capable of operating in the harsh Arctic environment ... -
Analysis of Transportation and Installation of a Component of an Artificial Sea Bed
Kjelsaas, Camilla (Master thesis, 2016)The purpose of this Master's Thesis was to study the transportation and installation of a bundle component to be used in an Artificial Seabed. The bundle, which is composed of three pipes and close to 4 km in length, is ... -
Application of a sea surface roughness formula using joint statistics of significant wave height and spectral wave steepness
Myrhaug, Dag; Leira, Bernt Johan; Chai, Wei (Journal article; Peer reviewed, 2020)This article provides some statistical features of the sea surface roughness given as a function of the spectral wave steepness and the significant wave height suggested by Taylor and Yelland (J Phys Oceanogr 31:572–590, ... -
Application of wave runup and wave rundown formulae based on long-term variation of wave conditions
Myrhaug, Dag; Leira, Bernt Johan (Journal article, 2017)The purpose of this note is to demonstrate that it is possible to use the proposed formulae in Blenkinsopp et al. [1] to estimate runup and rundown based on long-term variation of wave conditions by using the Myrhaug and ... -
Approaches for assessment of weld fatigue and verification of the effective notch stress approach
Fagnastøl, Øyvind Sæbø (Master thesis, 2014)Fatigue of welded structures is commonly assessed in three ways. These are the nominal stress-, the structural hot spot- and the effective notch stress approach. As the applicability of the approaches differs, these ... -
Approaches for assessment of weld fatigue and verification of the effective notch stress approach
Fagnastøl, Øyvind Sæbø (Master thesis, 2014)Fatigue of welded structures is commonly assessed in three ways. These are the nominal stress-, the structural hot spot- and the effective notch stress approach. As the applicability of the approaches differs, these ... -
Assessment of Hull Response due to Impact from Falling Object
Bergstad, Andreas (Master thesis, 2014)The present study assesses ship hull response of a platform supply vessel due to impact from falling objects. This is carried out primarily by investigating the critical energy absorption and localised deformation to ... -
Assessment of Methods for Short-Term Extreme Value Analysis of Riser Collision
Fu, Ping; Leira, Bernt Johan; Myrhaug, Dag (Chapter, 2018)Risers are commonly arranged as clusters with relatively small spacing due to economic necessity. As a consequence, collision between risers becomes an essential problem. This study presents a comprehensive assessment of ...