Wyniki wyszukiwania - BazTech

1

Methods of determination of C coefficient for period of rolling vessel in calm water for example of pax cargo ship

Królicka A.

TTS Technika Transportu Szynowego

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2013

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R. 20, nr 10

3531--3539

EN

This article presents a different approach to calculate the C coefficient needed to determine the period of own rolling vessel in calm water Tϕ = C·B / √GM. The C coefficient is usually adopted as the approximate value from the available literature, usually depending on the type of vessel, and less dependent on the loading condition. In experimental studies of marine properties (seakeeping) often have a problem with the selection of the correct value of the C coefficient, especially when we are dealing with an unusual type of ship, such as passenger and freight ship. In this article three approaches have been presented to determining the C coefficient. The difference in the obtained values of the C coefficient is about 10%, depending on the calculation method.

PL

W artykule zaprezentowano różne podejście do wyliczenia współczynnika C potrzebnego do wyznaczenia okresu kołysań własnych statku na wodzie spokojnej Tϕ = C·B / √GM. Współczynnik C zostaje najczęściej przyjęty jako przybliżona wartość z dostępnej literatury, najczęściej w zależności od typu statku, a słabiej zależy od stanu załadowania. Przy badaniach eksperymentalnych właściwości morskich bardzo często występuje problem z doborem prawidłowej wartości współczynnika C, zwłaszcza gdy mamy do czynienia z nietypowym rodzajem statku jak np. statek pasażersko-towarowy. W niniejszej pracy zaprezentowane zostały trzy podejścia do wyznaczania współczynnika C. Różnice w uzyskanych wartościach współczynnika C wynoszą około 10% w zależności od zastosowanej metody obliczeniowej.

2

Modelling of seakeeping qualities of open-top container carriers in the preliminary design phase

Cepowski T.

Polish Maritime Research

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2011

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nr 2

19-27

EN

In this paper are presented problems of modelling seakeeping qualities of open-top container carriers in the preliminary design phase. Approximations of accelerations and occurrence rate of green water ingress to holds are presented in function of main ship design and wave parameters. The approximations have been elaborated by applying theory of artificial neural networks in the wide range of ship hull dimensions and forms, while ship motion and wave parameters have been limited to real operational conditions described by means of the so called operational scenario. Such approach has made it possible to reach high accuracy of approximation and simple structure of mathematical model simulatneously.

3

Approximation of added resistance in waves based on ro-ro ferry main dimensions and wave parameters

Cepowski T.

Archives of Transport

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2011

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Vol. 23, iss. 4

435-445

EN

The methods herein described deal with predicting the added resistance in waves and may be useful in the preliminary stage of ro-ro ferry design. The research was aimed at replacing the complex numerical model with an approximating model based on the principal design parameters. To achieve this aim the author uses the methods of linear regression and theory of artificial neural networks. The resulting mathematical relationships allow to predict the added resistance in waves by utilizing the basic design parameters of the ship and wave parameters. The research results lead to a comparison of applicability of the linear regression and artificial neural networks theory in prediction of the added resistance in waves at the stage of ship parameters design.

PL

W pracy przedstawiono metody prognozowania dodatkowego oporu na fali przydatne na wstępnym etapie projektowania promów ro-ro. Celem badań było zastąpienie skomplikowanego modelu numerycznego prostym modelem aproksymacyjnym bazującym na podstawowych parametrach projektowych. Do osiągnięcia tego celu wykorzystano metody regresji liniowej oraz teorię sztucznych sieci neuronowych. W rezultacie opracowano zależności matematyczne pozwalające na przewidywanie dodatkowego oporu na fali na podstawie podstawowych parametrów projektowych statku i parametrów falowania. Uzyskane wyniki badań pozwoliły na porównanie możliwości wykorzystania regresji liniowej i teorii sztucznych sieci neuronowych do przewidywania dodatkowego oporu na fali na etapie parametrycznego projektowania statku.

4

The modeling of seakeeping qualities of Floating Production, Storage and Offloading (FPSO) sea-going ships in preliminary design stage

Cepowski T.

Polish Maritime Research

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2010

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nr 4

3-12

EN

This paper presents an analysis of a presently applied approach to accounting for seakeeping qualities of FPSO sea-going ships and possible using it in preliminary design stage. Approximations of heaving, pitching, green water ingress on the deck and slamming of FPSO ships, based on main ship design and wave parameters, are presented. The approximations were elaborated with the use of the linear regression method and theory of artificial neural networks for a very wide range of FPSO ship dimensions and hull forms. In the investigations ship operational conditions were limited to those occurring in real service of FPSO ships, described by means of the so called operational scenario. Such approach made it possible to reach simultaneously high approximation accuracy and simple structure of mathematical model.

5

Approximation of pitching motion of S-175 containership in irregular waves on the basis of ship's service parameters

Cepowski T.

Polish Maritime Research

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2006

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nr 1

22-25

EN

This paper presents approximations of pitching motion of S-175 containership in irregular waves within the full range of ship's service parameters. It continues the research described in [1] dealing with application of artificial neural networks to predict ship's motions. Reference pitch values were calculated by means of SEAWAY software based on accurate numerical methods. Approximating function was elaborated by using the artificial neural networks.