Browsing Institutt for marin teknikk by Author "Nielsen, Ulrik Dam"
Now showing items 1-20 of 27
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A brute-force spectral approach for wave estimation using measured vessel motions
Nielsen, Ulrik Dam; Brodtkorb, Astrid H.; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2018)The article introduces a spectral procedure for sea state estimation based on measurements of motion responses of a ship in a short-crested seaway. The procedure relies fundamentally on the wave buoy analogy, but the wave ... -
Automatic sea state estimation with online trust measure based on ship response measurements
Brodtkorb, Astrid Helene; Nielsen, Ulrik Dam (Peer reviewed; Journal article, 2022)The ever-changing sea state constitutes an integral part of situational awareness for vessels at sea. In this paper, a computationally efficient sea state estimation algorithm is extended by (1) automatic gain and tolerance ... -
Bayesian Estimation of Non-Stationary Ship Response Spectra
Møgster, Christian (Master thesis, 2015)The main topic of this master thesis is to obtain spectral information of non-stationary ship responses, with the motive of facilitating improvement of sea state estimation methods, that are using the wave buoy analogy. ... -
Deriving spatial wave data from a network of buoys and ships
Mounet, Raphaël Emile Gilbert; Chen, Jiaxin; Nielsen, Ulrik Dam; Brodtkorb, Astrid H.; Pillai, Ajit C.; Ashton, Ian G.C.; Steele, Edward C.C. (Peer reviewed; Journal article, 2023)The real-time provision of high-quality estimates of the ocean wave parameters at appropriate spatial resolutions are essential for the sustainable operations of marine structures. Machine learning affords considerable ... -
Deriving the absolute wave spectrum from an encountered distribution of wave energy spectral densities
Nielsen, Ulrik Dam (Journal article; Peer reviewed, 2018)The objective of ship motion-based wave spectrum estimation is to provide the distribution of wave energy densities in absolute domain. However, as a ship generally advances relative to the progressing waves, any spectrum ... -
Estimating waves via measured ship responses
Nielsen, Ulrik Dam; Bingham, Harry B.; Brodtkorb, Astrid H.; Iseki, Toshio; Jensen, Jørgen Juncher; Mittendorf, Malte; Mounet, Raphaël Emile Gilbert; Shao, Yanlin; Storhaug, Gaute; Sørensen, Asgeir Johan; Takami, Tomoki (Peer reviewed; Journal article, 2023)Optimisation of energy efficiency and operational performance as well as assessment of safety levels and emissions of marine operations require detailed information about the acting wave system. It is possible—with an ... -
Estimation of autocorrelation function and spectrum density of wave-induced responses using prolate spheroidal wave functions
Takami, Tomoki; Nielsen, Ulrik Dam; Jensen, Jørgen Juncher (Peer reviewed; Journal article, 2021)Predicting the wave-induced response in the near-future is of importance to ensure safety of ships. To achieve this target, a possible method for deterministic and conditional prediction of future responses utilizing ... -
Estimation of Extreme Roll Motion Using the First Order Reliability Method
choi, ju-hyuck; Jensen, Jørgen Juncher; Nielsen, Ulrik Dam (Chapter, 2021)Extreme value statistics can often be based on the assumption that exceedance events of a high threshold level are statistically independent and identically distributed (i.i.d. process), which further implies the Poisson ... -
Evaluation of Shipboard Wave Estimation Techniques Through Model-scale Experiments
Nielsen, Ulrik Dam; Galeazzi, Roberto; Brodtkorb, Astrid H. (Chapter, 2016)The paper continues a study on the wave buoy analogy that uses shipboard measurements to estimate sea states. In the present study, the wave buoy analogy is formulated directly in the time domain and relies only partly on ... -
How good is the stw sensor? An account from a larger shipping company
Ikonomakis, Angelos; Nielsen, Ulrik Dam; Holst, Klaus; Dietz, Jesper; Galeazzi, Roberto (Journal article; Peer reviewed, 2021) -
Hybrid Control of Marine Vessels: Dynamic Positioning in Varying Conditions
Brodtkorb, Astrid H. (Doctoral theses at NTNU;2017:351, Doctoral thesis, 2017)The next generation marine control systems will, as a step towards increased autonomy, have more automatic functionality in order to cope with a set of complex operations in unknown and varying environments, while maintaining ... -
Indirect Measurements of Added-Wave Resistance on an In-Service Container Ship
Nielsen, Ulrik Dam; Johannesen, Jacob R.; Bingham, Harry B.; Blanke, Mogens; Joncquez, Soizic (Chapter, 2021)This paper investigates a semi-empirical model used to estimate added-wave resistance on a ship sailing in waves. The model relies on measurements from a continuous monitoring system, and produces an estimate - the indirect ... -
Ocean wave spectrum estimation using measured vessel motions from an in-service container ship
Nielsen, Ulrik Dam; Dietz, Jesper (Peer reviewed; Journal article, 2020)This article is about the use of measured wave-induced vessel motions for estimation of ocean wave spectra by application of the wave buoy analogy. In the study, data from a larger, in-service container ship is considered. ... -
Online wave estimation using vessel motion measurements
Brodtkorb, Astrid H.; Nielsen, Ulrik Dam; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2018)In this paper, a computationally efficient online sea state estimation algorithm is proposed for estimation of the onsite sea state. The algorithm finds the wave spectrum estimate from motion measurements in heave, roll ... -
Parameterised transfer functions with associated confidence bands
Nielsen, Ulrik Dam; Mounet, Raphaël Emile Gilbert; Brodtkorb, Astrid H. (Peer reviewed; Journal article, 2022)This paper presents a method that can be used to obtain the motion transfer functions of a ship when the detailed hull geometry is not available. In the method, any parameterised transfer function can be optimised from a ... -
Prediction of ships’ speed-power relationship at speed intervals below the design speed
Berthelsen, Frederik H.; Nielsen, Ulrik Dam (Peer reviewed; Journal article, 2021) -
Preliminary assessment of increased main engine load as a consequence of added wave resistance in the light of minimum propulsion power
Holt, Philip; Nielsen, Ulrik Dam (Journal article; Peer reviewed, 2021)This paper addresses the connection between added wave resistance and required propulsion power of ships, having focus on the early stage of new ship designs, notably tankers and bulk carriers. The paper investigates how ... -
Real-time deterministic prediction of wave-induced ship responses based on short-time measurements
Takami, Tomoki; Nielsen, Ulrik Dam; Jensen, Jørgen Juncher (Peer reviewed; Journal article, 2021)This paper studies real-time deterministic prediction of wave-induced ship motions using the autocorrelation functions (ACFs) from short-time measurements, namely the instantaneous ACFs. The Prolate Spheroidal Wave Functions ... -
Response predictions using the observed autocorrelation function
Nielsen, Ulrik Dam; Brodtkorb, Astrid H.; Jensen, Jørgen Juncher (Journal article; Peer reviewed, 2018)This article studies a procedure that facilitates short-time, deterministic predictions of the waveinduced motion of a marine vessel, where it is understood that the future motion of the vessel is calculated ahead of time. ... -
Sea state estimation using model-scale DP measurements
Brodtkorb, Astrid H.; Nielsen, Ulrik Dam; Sørensen, Asgeir Johan (Chapter, 2015)Complex marine operations are moving further from shore, into deeper waters, and harsher environments. The operating hours of a vessel are weather dependent, and good knowledge of the prevailing weather conditions may ...