Author
Xu Han
Other affiliations: DNV GL
Bio: Xu Han is an academic researcher from Norwegian University of Science and Technology. The author has contributed to research in topics: Sensitivity (control systems) & Seakeeping. The author has an hindex of 3, co-authored 7 publications receiving 26 citations. Previous affiliations of Xu Han include DNV GL.
Papers
More filters
TL;DR: The algorithm is found to be computationally efficient, robust and stable when tuning the values of hydrodynamic parameters and updating their uncertainties, within reasonable sensor noise levels.
18 citations
TL;DR: A nonparametric approach for directional wave spectrum estimation based on vessel motion responses is presented, which introduces novel smoothness constraints using Bezier surface and includes a more robust estimate using L1 optimization.
17 citations
18 Dec 2020
TL;DR: A case study is presented for identifying the most sensitive parameters in the vessel hydrodynamic model w.r.t. the vessel motion RAOs and shows that the parametric sensitivity depends on the interesting vessel response parameter, wave direction and loading condition.
Abstract:
In the recent decade, maritime and energy industries have realized the potential of using operational data in combination with a virtual replication of the real physical asset, termed the digital twin. The digital twin then serves as a platform for data management, asset monitoring, and inspection and maintenance management, featuring an improved basis for cost effective operations and future decision making in terms of e.g. life extension. The present paper deals with application of the digital twin concept in marine operations where it is essential to handle the inherent uncertainties of vessel performance by applying a model that can adapt to the real operating conditions. In this paper a case study is presented for identifying the most sensitive parameters in the vessel hydrodynamic model w.r.t. the vessel motion RAOs. The study also shows that the parametric sensitivity depends on the interesting vessel response parameter, wave direction and loading condition. A digital twin adaptive to various operational conditions may require parametric tuning of the numerical model. It is important to identify the correct parameter(s) for modification. A simplified and idealized case study is also carried out to test the requirements to a successful parameter identification for model tuning.
6 citations
TL;DR: Two different procedures for tuning the sea state dependent roll damping coefficient together with other uncertain vessel parameters are proposed, i.e., 1- step tuning and 2-step tuning procedures, and aRoll damping prediction model based on Gaussian process regression is proposed to predict the roll damped for future sea states based on historical data.
5 citations
TL;DR: A novel algorithm for simultaneous tuning of important vessel seakeeping model parameters and sea state characteristics based on onboard vessel motion measurements and available wave data is proposed, fundamentally based on the unscented transformation and inspired by the scaled unscenting Kalman filter.
5 citations
Cited by
More filters
TL;DR: The state-of-the-art research on OWT maintenance is reviewed, covering strategy selection, schedule optimization, onsite operations, repair, assessment criteria, recycling, and environmental concerns.
Abstract: Operations and maintenance of offshore wind turbines (OWTs) play an important role in the development of offshore wind farms. Compared with operations, maintenance is a critical element in the levelized cost of energy, given the practical constraints imposed by offshore operations and the relatively high costs. The effects of maintenance on the life cycle of an offshore wind farm are highly complex and uncertain. The selection of maintenance strategies influences the overall efficiency, profit margin, safety, and sustainability of offshore wind farms. For an offshore wind project, after a maintenance strategy is selected, schedule planning will be considered, which is an optimization problem. Onsite maintenance will involve complex marine operations whose efficiency and safety depend on practical factors. Moreover, negative environmental impacts due to offshore maintenance deserve attention. To address these issues, this paper reviews the state-of-the-art research on OWT maintenance, covering strategy selection, schedule optimization, onsite operations, repair, assessment criteria, recycling, and environmental concerns. Many methods are summarized and compared. Limitations in the research and shortcomings in industrial development of OWT operations and maintenance are described. Finally, promising areas are identified with regard to future studies of maintenance strategies.
154 citations
TL;DR: In this paper , a data-driven parametric model identification of a ship with 6 degrees of freedom (6DOF) exposed to waves using sparse regression according to the vessel motion measurements is proposed.
37 citations
TL;DR: The algorithm is found to be computationally efficient, robust and stable when tuning the values of hydrodynamic parameters and updating their uncertainties, within reasonable sensor noise levels.
18 citations
TL;DR: A nonparametric approach for directional wave spectrum estimation based on vessel motion responses is presented, which introduces novel smoothness constraints using Bezier surface and includes a more robust estimate using L1 optimization.
17 citations
TL;DR: Inspired by the knowledge of inverse dynamics and range-based localization, a general model-free anti-swing control scheme is proposed that has a simple form without considering state–space equations, but it can reduce the pendular payload motion regardless of the detailed system configuration.
12 citations