| 1. |
- Lindgren, Georg, et al.
(author)
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Wave characteristics distributions for Gaussian waves - wave-length, amplitude and steepness
- 1982
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In: Ocean Engineering. - : Elsevier BV. - 1873-5258 .- 0029-8018. ; 9:5, s. 411-432
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Journal article (peer-reviewed)abstract
- In as tationary stochastic process the wave-length and amplitude are defined as the difference in time and height between a crest and the following trough. The distributions of these quantities are of great practical importance, but no closed form expressions are known at present. In previous papers we have presented an approximation which gives correct upper and lower bounds, regardless of the covariance structure under Gaussian assumptions. In this paper the suggested approximations are compared to two simpler approximations, one due to Cavanié et al. (1976) based on a cosine process and a new one, derived by replacing the model process by its regression curve.
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| 2. |
- Alexandersson, Martin, et al.
(author)
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System identification of Vessel Manoeuvring Models
- 2022
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In: Ocean Engineering. - : Elsevier Ltd. - 0029-8018 .- 1873-5258. ; 266
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Journal article (peer-reviewed)abstract
- Identifying the ship's maneuvering dynamics can build models for ship maneuverability predictions with a wide range of useful applications. A majority of the publications in this field are based on simulated data. In this paper model test data is used. The identification process can be decomposed into finding a suitable manoeuvring model for the hydrodynamic forces and to correctly handle errors from the measurement noise. A parameter estimation is proposed to identify the hydrodynamic derivatives. The most suitable manoeuvring model is found using the parameter estimation with cross-validation on a set of competing manoeuvring models. The parameter estimation uses inverse dynamics regression and Extended Kalman filter (EKF) with a Rauch Tung Striebel (RTS) smoother. Two case study vessels, wPCC and KVLCC2, with very different maneuverability characteristics are used to demonstrate and validate the proposed method. Turning circle predictions with the robust manoeuvring models, trained on zigzag model tests, show good agreement with the corresponding model test results for both ships. © 2022 The Author(s)
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| 3. |
- Anand, R. S., et al.
(author)
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A comprehensive review on Crossflow turbine for hydropower applications
- 2021
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In: Ocean Engineering. - : Elsevier BV. - 0029-8018 .- 1873-5258. ; 240
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Research review (peer-reviewed)abstract
- A Crossflow turbine is a device used to generate power from hydro, which is a renewable source of energy. The salient feature of this turbine is its simplicity in construction. In the past few decades, variables such as flow diverter, air holes, bidirectional flow were introduced in the turbine design to improve its efficiency. This paper presents a comprehensive review of the performance of the cross flow turbine. The review of literature is classified into experimental and numerical studies. The present study highlights the optimum range of geometrical variables required for the efficient design of a cross flow turbine. The study also emphasizes the importance of employing the cross flow turbine in remote places where run-of-river hydro power plants are feasible, as it provides a low-cost energy solution. The outcome of the present study will help the researchers to identify the research gap based on the present status of work done and to improve the performance of the cross flow turbine further in the future.
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| 4. |
- Andersson, C., et al.
(author)
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Fully electric ship propulsion reduces airborne noise but not underwater noise
- 2024
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In: Ocean Engineering. - Göteborg : Elsevier. - 0029-8018 .- 1873-5258. ; 302
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Journal article (peer-reviewed)abstract
- Electrification of ships offers zero-emission travel and is spreading rapidly, but the relation between electric ship propulsion and noise pollution is not generally understood. Here, three different types of diesel-electric hybrid ferries have been measured in two operating modes: running in hybrid mode with the diesel engine powering an electric generator; and running in fully electric battery powered mode. Measurements were performed to simultaneously quantify airborne and underwater radiated noise. Findings are that on-board diesel engines for electricity generation do not contribute a large extent of the underwater radiated noise, whilst a major source of airborne low-frequency radiation.
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| 5. |
- Bačkalov, I., et al.
(author)
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Improvement of ship stability and safety in intact condition through operational measures : Challenges and opportunities
- 2016
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In: Ocean Engineering. - : Elsevier. - 0029-8018 .- 1873-5258. ; 120, s. 353-361
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Journal article (peer-reviewed)abstract
- Attaining a sufficient level of safety from the point of view of stability is typically considered to be a matter of design. However, it is impossible to ensure safety only by design measures, and operational measures can then represent a complementary tool for efficiently and cost-effectively increasing the overall safety of the vessel. Time could therefore be coming for systematically considering operational measures as a recognised and regulated integral part of a holistic approach to ship safety from the point of view of stability. This paper therefore aims at capturing recent trends of research targeting operational safety measures, with specific attention to the intact ship condition. Open challenges and opportunities for research are identified, potential benefits and shortcomings of different options are discussed, and needs and possibilities for further developments in this area are explored. As an overall goal, this paper aims at providing food for thoughts as well as a ground for further proceeding towards the target of implementing a virtuous integrated approach to intact ship safety, from the point of view of stability, which gives due credit to effective and robust operational risk control options.
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| 6. |
- Bačkalov, I., et al.
(author)
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Ship stability, dynamics and safety : Status and perspectives from a review of recent STAB conferences and ISSW events
- 2016
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In: Ocean Engineering. - : Elsevier. - 0029-8018 .- 1873-5258. ; 116, s. 312-349
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Research review (peer-reviewed)abstract
- In Naval Architecture, the concept of "stability" has a very wide meaning, embracing ship stability fundamentals with ship dynamics and ultimately ship safety. As such, the subject is of paramount importance for its wide implications on design and operation of ships and floating units. Research in this field has, therefore, an important impact on the fleet safety, and the International Conferences on Stability of Ships and Ocean Vehicles (STAB Conferences) and the International Ship Stability Workshops (ISSW) are certainly the venues where expertise and contemporary developments in this specific field tend to be collected and thoroughly debated. With the aim of analysing the current status and possible future perspectives of research in the field of ship stability, dynamics and safety, this paper provides an extensive review of the findings presented at STAB Conferences and ISSW events in the period 2009-2014. The reviewed material is organised according to a set of identified macro-topics of research. On the basis of the reviewed material, consolidated research topics as well as emerging subjects are laid out, and ideas for possible future research are also brought forward. Discussion is also provided regarding the link between research and educational aspects.
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| 7. |
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| 8. |
- Baxevani, Anastassia, et al.
(author)
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Maxima for Gaussian seas
- 2006
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In: Ocean Engineering. - : Elsevier BV. - 1873-5258 .- 0029-8018. ; 33:7, s. 895-911
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Journal article (peer-reviewed)abstract
- The probability distribution of the height of global maximum for a Gaussian random field evolving in time is studied. In particular, the effect of spreading is studied and the role of the wave kinematics is discussed. It is observed that taking into account time dynamics of spatial characteristics results in distributions different from those obtained for the static case. The results are illustrated by computing the derived distribution for different Gaussian seas for three distinct sampling schemes. The resulting distributions are also used to compute return periods for rogue waves. (c) 2005 Elsevier Ltd. All rights reserved.
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| 9. |
- Begovic, Ermina, et al.
(author)
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Experimental modelling of local structure responses for high-speed planing craft in waves
- 2020
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In: Ocean Engineering. - : Elsevier Ltd. - 0029-8018 .- 1873-5258. ; 216
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Journal article (peer-reviewed)abstract
- The modelling of planing craft dynamics in waves and related fluid-structure interaction is a hard challenge due to the highly nonlinear, transient and stochastic nature of the whole process. This paper explores the prospectives of detailed experimental modelling of the local structure responses for high-speed planing craft in waves. A novel experimental setup is presented where a well-defined model structure is integrated into the hull bottom of a typical planing craft model. The model is instrumented for measuring strains in the model structure, related slamming pressures, craft rigid body motions and accelerations. The experimental setup is thoroughly described and motivated and crucial aspects of the setup are verified through testing in idealized static loading conditions and by modal analysis. The capabilities of the experimental setup are demonstrated through systematic experiments in regular waves. The most indicative results are presented and discussed in relation to corresponding results from time-domain simulations The presented experimental modelling approach is concluded to enable uniquely detailed studies of the complete slamming related fluid-structure interaction process and provides a good tool for further research and development towards establishment of first principles-based methods for hydrodynamic and structure design of high-speed planing craft.
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| 10. |
- Bilandi, R. N., et al.
(author)
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Hydrodynamic study of heeled double-stepped planing hulls using CFD and 2D+T method
- 2020
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In: Ocean Engineering. - : Elsevier Ltd. - 0029-8018 .- 1873-5258. ; 196
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Journal article (peer-reviewed)abstract
- In the current paper, we have developed a method, based on 2D+T theory, to model the performance of doubled-stepped planing hulls in asymmetric conditions. We have performed Computational Fluid Dynamics (CFD) simulations to evaluate the difference between the results of the 2D+T method and CFD. We have validated 2D+T and CFD simulations. The quantitative comparison between the results of both methods shows they predict almost similar heeling moment, resistance and trim angle for a doubled-stepped planing hull. Results of non-stepped and doubled-stepped planing hulls are compared against each other, demonstrating that an increase in heel angle has less influence on the performance of the doubled-stepped planing hull. The heeling moment of a double-stepped planing hull is found to be smaller than a heeling moment of a non-stepped planing hull at early planing speeds, but, by the increase in speed, heeling moment of doubled-stepped planing hulls becomes slightly larger.
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