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    Tytuł:
    Application of statistical methods and artificial neural networks for approximating ships roll in beam waves
    Autorzy:
    Cepowski, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/259233.pdf
    Data publikacji:
    2005
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    ship's roll
    irregular wave
    approximation
    neural networks
    regression methods
    Opis:
    In the paper, were presented approximations of numerical calculations of ship's roll on the basis of main service parameters of the ship. This way were obtained several relationships which make it possible to approximate ship roll in regular and irregular waves by using the parameters available in the phase of voyage routing. The relationships were elaborated by means of artificial neural networks as well as linear and non-linear regression methods. A comparative analysis of the methods regarding approximation accuracy against standard data was also performed.
    Źródło:
    Polish Maritime Research; 2005, 2; 22-28
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental study of hydraulic response of smooth submerged breakwaters to irregular waves
    Autorzy:
    Mahmoudof, S.M.
    Hajivalie, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/2078821.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    submerged breakwater
    irregular wave
    experimental study
    transmission
    reflection
    coastal area
    Opis:
    This paper presents the results of a laboratory experiment on transmission, reflection, and dissipation of irregular waves over smooth impermeable submerged breakwaters. Experiments included 75 JONSWAP-based irregular waves with five different wave characteristics generated at three water depths in a 2D wave flume. The investigated breakwater sections were three rectangular breakwaters with different widths, a toothed rectangular breakwater, and a trapezoidal breakwater with a slope of 1:2. A new comprehensive dimensionless parameter (β) was proposed representing both wave hydrodynamic and breakwater geometry characteristics. This parameter could be employed as a suitable descriptive option to make an accurate estimate of the hydraulic performances of submerged breakwaters. The β parameter is composed of four conventional simple dimensionless variables. However, the results revealed that the relative submergence depth significantly affects the hydraulic responses of submerged breakwaters. The transmission, reflection and dissipation of waves show a logarithmic growth, a logarithmic reduction, and a quadratic decreasing trend against the increasing of β parameter, respectively. The verifications of results revealed the high efficiency of β parameter for data reported by Carevic et al. (2013) with R2 = 0.88 and high agreement with predictions made by Van der Meer et al. (2005) formulation with R2 = 0.93.
    Źródło:
    Oceanologia; 2021, 63, 4; 448-462
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transformation of statistical and spectral wave periods crossing a smooth low-crested structure
    Autorzy:
    Carevic, D.
    Loncar, G.
    Prsic, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/48874.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    transformation
    wave parameter
    statistical method
    spectral method
    breakwater
    empirical model
    irregular wave
    nonlinear interaction
    water depth
    Opis:
    We carried out experimental studies of a smooth submerged breakwater in a wave channel in order to study such a structure impacts on the changes of statistically and spectrally defined representative wave periods as waves cross it. We discuss the impact of relative submersion, i.e. the relationship between the breakwater crown submersion and the incoming significant wave length Rc/Ls−i, on the representative wave periods. The mean periods, estimated using statistical and spectral methods, were compared in front of and behind the breakwater: the two periods turned out to be identical. Based on the measurements of the spectral mean wave periods in front of and behind the breakwater, an empirical model is derived for estimating the reduction in mean spectral period for submerged and emerged smooth breakwaters.
    Źródło:
    Oceanologia; 2012, 54, 1
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of propeller emergence on the load of a marine engine of a ship sailing on irregular wave
    Autorzy:
    Szelangiewicz, T.
    Żelazny, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/360221.pdf
    Data publikacji:
    2013
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    ship motions on irregular wave
    propeller emergence
    decrease in torque value of a propeller
    Opis:
    When a ship is saling on waves the relative motions occur which result in propeller emergence, and as a consequence – propeller thrust reduction which results in a decrease in the ship’s speed. Propeller emergence is also accompanied by the decrease in torque values, with which the propeller affects the marine engine. The article presents both calculation results and the algorithm for calculating the decrease in torque of the propeller during ship motions on irregular wave.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2013, 35 (107); 144-148
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation of life raft motions on irregular wave - an analysis of situations leading to raft capsizing
    Autorzy:
    Kazimierska, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/260566.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    life rafts
    inflatable rafts
    circular rafts
    drift anchors
    simulations of motions on irregular wave
    raft dynamics
    wave spectrum
    Opis:
    Successful rescue action at sea is based on a. o. a correct choice of rescue means and their reliability. Operational characteristics of life-saving appliances determine their performance in a given water area. Therefore they affect duration time of rescue action and decide this way on survival time of shipwrecked persons. This paper presents impact of characteristics of circular inflatable life rafts on their dynamics in a given sea environment. Particular issues dealing with raft motion were analyzed and their solutions were then presented in the form of computer programs built into MATLAB environment. The programs operate on the open choice basis– the user is requested to introduce data of a raft to be investigated. The program clearly informs which units should be used for the data. The obtained results allow to limit survivours searching area and simultaneously form the basis for working out a model of searched object drift motion. In this work the use was made of the results obtained from the KBN research project No. 4T12C03827 in which an attempt was made to analyzing capsize probability of a raft at given sea states. The raft investigated in the project is also used as a reference raft in the computer programs developed in this work.
    Źródło:
    Polish Maritime Research; 2018, S 1; 42-50
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the geometry of ocean surface waves
    Autorzy:
    Massel, S.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/48766.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    air-sea interaction
    atmosphere-ocean interaction
    deep water
    dynamic factor
    geometry
    irregular wave
    marine environment
    ocean surface
    regular wave
    shallow water
    surface wave
    water motion
    wave breaking
    wave slope
    Opis:
    The factors influencing the atmosphere-ocean transfer of mass and momentum, as well as incipient wave breaking and the amount of energy dissipated due to breaking, are discussed in detail. In particular, the influence of directional spreading on the statistics of surface wave slopes and the area of the wind- roughened ocean surface is demonstrated. Theoretical analysis and comparison with the available experimental data show that unimodal directional spreading is not able to reproduce the observed ratio of the cross-wind/up-wind mean square slopes. Better agreement is achieved when bimodal directional spreading, consisting of two wrapped-Gaussian distributions, is applied. The bimodal form suggested by Ewans (1998) is used in the paper. Moreover, the formulae developed here show that the increase in the area due to surface waves is rather small for both regular and irregular waves.
    Źródło:
    Oceanologia; 2011, 53, 2
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Approximating the added resistance coefficient for a bulk carrier sailing in head sea conditions based on its geometrical parameters and speed
    Autorzy:
    Cepowski, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/258482.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    bulk carrier
    resistance
    added wave resistance
    added resistance coefficient
    regular wave
    irregular wave
    ship designing
    preliminary design stage
    artificial neural networks
    approximation
    forecasting
    speed
    waterplane area
    waterplane coefficient
    sample case
    task
    designing
    Opis:
    The article presents the mathematical function to calculate the added wave resistance transfer function for bulk carriers. Based on this function, the statistical mean added wave resistance generated by an irregular head wave with arbitrary statistical parameters can be forecasted. The input parameters are: waterplane area, waterplane coefficient, ship speed, and frequency of the regular wave. The model has been developed based on the theory of artificial neural networks. The presented function can be used in design analyses, and for planning shipping routes in situations when basic geometrical parameters of the hull are only available and not the full technical documentation. The article presents sample cases of use of this function to calculate the added wave resistance transfer function and the statistical mean added wave resistance. Another presented application refers to waterplane coefficient optimisation taking into account the added wave resistance at the stage of preliminary bulk carrier design.
    Źródło:
    Polish Maritime Research; 2016, 4; 8-15
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Aproksymacja kołysań bocznych kontenerowca S-175 na fali nieregularnej oparta na parametrach eksploatacyjnych statku
    Approximation of Roll Amplitudes of a S-175 Containership in Irregular Waves on the Basis of Main Service Parameters
    Autorzy:
    Cepowski, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/906314.pdf
    Data publikacji:
    2005
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    Inżynieria Ruchu Morskiego 2005
    właściwości morskie
    kołysania boczne
    sztuczne sieci neuronowe
    aproksymacja
    parametry eksploatacyjne
    fala nieregularna
    seakeeping
    roll
    artificial neural networks
    approximation
    service parameters
    irregular wave
    Opis:
    Przedstawiono aproksymację kołysań bocznych kontenerowca S-175 na fali nieregularnej opartą na parametrach eksploatacyjnych statku. Wartości wzorcowe kołysań bocznych obliczono dokładnymi metodami numerycznymi za pomocą programu SEAWAY. Funkcję aproksymacyjną opracowano za pomocą sztucznych sieci neuronowych i przedstawiono w postaci analitycznej. Prezentowana metodyka może pozwolić na prognozowanie rzeczywistych wartości kołysań bocznych, opartych na danych zarejestrowanych na statku.
    The paper presents approximations of roll amplitudes of a S-175 containershipoccurring in irregular waves on the basis of main service parameters. Standard values of ship's roll were determined by means of exact numerical methods by using the SEAWAY software. The relationships were elaborated by means of artificial neural networks and presented as an analytical function. The proposed approach may be used to approximate real values of roll angle amplitude on the basis of data recorded onboard the ship during its service.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2005, 6 (78); 65-75
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact of waves on dangerous stability of vessels on the oceanic route
    Autorzy:
    Szelangiewicz, T.
    Żelazny, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/27315945.pdf
    Data publikacji:
    2018
    Wydawca:
    STE GROUP
    Tematy:
    nieregularna fala
    toczenie się statku
    stabilność na belce i podążanie za falami
    zmienny moment prostujący
    irregular wave
    rolling of a vessel
    stability on beam and following waves
    variable righting moment
    Opis:
    Stability is one of the most important properties of the ship. The greatest influence on stability and thus on the possibility of loss of stability have the rolling of the ship on the wave. Mathematical models describing rolling on wave are complicated, and their solution, especially in the irregular wave, is only possible with numerical methods in the time domain. Large rolling, until the ship capsize, formation not only on the beam wave, but also on the following wave. Various models describing rolling (linear and nonlinear, regular and irregular wave, and constant or variable restoring moment) are presented. The predicted level hazard of stability of the ship depends on the direction of the wave and the cases where the level of hazard will be greatest.
    Źródło:
    New Trends in Production Engineering; 2018, 1, 1; 469-477
    2545-2843
    Pojawia się w:
    New Trends in Production Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation of irregular waves in a numerical wave tank
    Autorzy:
    Li, Z-F.
    Shi, Y. Y.
    Ren, H. L.
    Li, H.
    Ashraf, M. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/260392.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    open boundary condition
    multi transmitting formula
    irregular waves
    boundary element method
    numerical wave tank
    Opis:
    The time domain boundary element method was utilized to simulate the propagation of the irregular waves in a numerical wave tank. The problem was solved in a time-marching scheme, upon the irregular waves being fed through the inflow boundary, in which the theoretical solution was obtained from the wave energy spectrum. The open boundary condition was modeled by the multi transmitting formula (MTF), in which the phase velocity was calculated according to the Sommerfeld’s condition. The velocity potential and wave elevation were directly obtained by integrating the free surface condition twice, with respect to time. The accuracy of the developed numerical scheme was verified by simulating the propagation of irregular waves. The numerical results show good agreements with the analytical solutions, which prove that the proposed scheme is a promising way to the simulation of wave-body interactions.
    Źródło:
    Polish Maritime Research; 2015, S 1; 21-25
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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