Searched for: author%3A%22Vrijdag%2C+A.%22
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Huijgens, L.J.G. (author), Vrijdag, A. (author), Hopman, J.J. (author)
The interaction between ship propulsion machinery, propellers and the highly dynamic environment which is the sea is a complex yet highly relevant subject. During a storm, for example, waves and ship motions may cause the propeller to draw air, or ventilate, resulting in rapid changes in propeller thrust and load torque. These fluctuations...
journal article 2022
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Huijgens, L.J.G. (author), Vrijdag, A. (author), Hopman, J.J. (author)
Standards for environmental impact, safety and operational performance of ships are becoming increasingly strict. In order to meet these standards, the performance of new ship designs must be predicted with an increasing level of detail and confidence. As present prediction methods lack realistic, dynamic behaviour of the ship's propulsion plant...
journal article 2021
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Vrijdag, A. (author), Martelli, M. (author)
Simulation models of the ship propulsion system play an increasingly important role, for instance in controller design and condition monitoring. However, creation of such simulation models requires significant time and effort. In this paper, the application of deterministic identification techniques on a DC-electric ship drive train is explored...
journal article 2021
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van der Kolk, N.J. (author), Bordogna, G. (author), Mason, J.C. (author), Desprairies, P. (author), Vrijdag, A. (author)
In this paper, a vessel model for the performance of wind-assisted ships is combined with a routing tool to assess the fuel savings available from the installation of both one and two Flettner rotors when travelling along a Great Circle Route path. This is combined with an economic analysis to assess commercial viability for these hybrid...
conference paper 2019
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Vrijdag, A. (author), Schuttevaer, D. (author)
Dramatic increases in the underwater acoustic signature of ships have been observed during full scale trials in a seaway, compared to calm water conditions. The observed behaviour can be explained by the interaction of waves, wake field and ship propulsion system dynamics in combination with rudder action and ship motions. This paper explores...
journal article 2019
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Vrijdag, A. (author), Sang, Yueming (author)
In this paper the concept of ship propulsion system “fingerprinting” is explored as an alternative for data driven models that require extensive measured datasets collected over long periods of ship operation. As a first exploratory step a model of a ship in bollard pull conditions is linearised and its transfer functions are determined....
conference paper 2018
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Kok, R. (author), Vrijdag, A. (author), van 't Veer, A.P. (author), Abbink, D.A. (author)
Crew of small fast ships often experiences excessive vertical accelerations when sailing in waves, leading to discomfort and injuries. In an attempt to avoid this, experienced operators reduce speed voluntarily when they anticipate that the next vertical peak acceleration will be unacceptably large. However, at night and during excessive spray,...
conference paper 2018
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Vrijdag, A. (author), Boonen, Erik-Jan (author), Lehne, Markus (author)
Results of trade-off studies aiming to compare different ship power and propulsion configurations inherently contain uncertainty. This is true for both the technical part and for the financial part of the trade-off study. The technical part typically includes the system characteristics of the vessel as inputs, resulting in predicted fuel...
journal article 2018
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Huijgens, L.J.G. (author), Vrijdag, A. (author), Hopman, J.J. (author)
Regulatory demands on ship designs, such as emission and manoeuvrability requirements, are becoming increasingly stringent, raising the need for advanced methods to predict and assess dynamic propulsion plant behaviour of a new design. At present, model scale experiments and numerical simulations are not able to predict this behaviour in full...
conference paper 2018
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Stapersma, D. (author), Vrijdag, A. (author)
The understanding, modelling and analysis of the behaviour of a non-linear ship propulsion plant are of great importance for conceptual system design, component selection, selection of control strategy and for propulsion control system tuning. Conceptual propulsion system design activities, such as deciding the combinator curve, require a...
journal article 2017
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Vrijdag, A. (author)
Traditionally, model scale tests of ships are carried out without taking into account the dynamics of the shipboard systems that are involved in the operation under consideration. An example of this is the way that model scale free sailing tests in waves are carried out. The ship model is mounted with an electric motor, shaft and propeller...
conference paper 2016
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Vrijdag, A. (author)
conference paper 2015
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Vrijdag, A. (author)
conference paper 2012
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Vrijdag, A. (author), de Vos, P. (author)
An important aspect for a new-built vessel is the contract speed. Not reaching the contract speed can lead to penalties for the shipbuilder and dissatisfaction for the customer, while an under-predicted contract speed can lead to non-competitive design and a lower income for the shipbuilder. The performance of a new-built vessel is uncertain due...
conference paper 2012
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Vrijdag, A. (author), Stapersma, D. (author), van Terwisga, T.J.C. (author)
journal article 2010
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Giles, W. (author), Dinham-Peren, T. (author), Amaratunga, S. (author), Vrijdag, A. (author), Partridge, R. (author)
conference paper 2010
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Vrijdag, A. (author)
Off design conditions can have a severe impact on ship propulsion system behaviour. Resistance increase for instance leads to a higher engine loading, and can also easily lead to a decrease of cavitation inception speed with respect to calm water conditions. Wakefield variations due to ship motions, waves and manoeuvres also have effect on...
doctoral thesis 2009
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Vrijdag, A. (author)
conference paper 2009
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