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Tytuł:
Information about dynamics of the sea surface as a means to improve safety of the unmanned vessel at sea
Autorzy:
Przyborski, M.
Powiązania:
https://bibliotekanauki.pl/articles/259934.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
hypothesis testing
nonlinearity
sea dynamics
USV
Opis:
One of the fundamental states of the sea surface is its heave. Despite of years of the intense scientific inquiry, no clear understanding of the influence of this aspect on the dynamics of the sea environment has emerged. The separation of two nearby fluid elements which one may observed for example as a free floating of small objects on the sea surface (rescuers on the rough sea or small research vessels) is caused by the interaction of different components. On the other hand one may say that the heave of the sea is also a summary interaction of a few components describing the dynamics of the sea. Therefore it is the most important aspect, which influenced the dispersion phenomenon. This observation has important consequences for many different problems as for example conducting Search and Rescue missions and using unmanned ships. We would like to present results of our experiment focused on finding the answer to question about nature of the heave of the sea and its influence on safety of Unmanned Surface Vessels (USV).
Źródło:
Polish Maritime Research; 2016, 4; 3-7
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SPH Modelling of Sea-ice Pack Dynamics
Autorzy:
Staroszczyk, R.
Powiązania:
https://bibliotekanauki.pl/articles/241351.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
sea-ice dynamics
Lagrangian description
smoothed particle hydrodynamics
moving boundary problem
Opis:
The paper is concerned with the problem of sea-ice pack motion and deformation under the action of wind and water currents. Differential equations describing the dynamics of ice, with its very distinct mateFfigrial responses in converging and diverging flows, express the mass and linear momentum balances on the horizontal plane (the free surface of the ocean). These equations are solved by the fully Lagrangian method of smoothed particle hydrodynamics (SPH). Assuming that the ice behaviour can be approximated by a non-linearly viscous rheology, the proposed SPH model has been used to simulate the evolution of a sea-ice pack driven by wind drag stresses. The results of numerical simulations illustrate the evolution of an ice pack, including variations in ice thickness and ice area fraction in space and time. The effects of different initial ice pack configurations and of different conditions assumed at the coast–ice interface are examined. In particular, the SPH model is applied to a pack flow driven by a vortex wind to demonstrate how well the Lagrangian formulation can capture large deformations and displacements of sea ice.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2017, 64, 2; 115-137
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Consequences of global warming in cryosphere
Autorzy:
Jania, Jacek A.
Powiązania:
https://bibliotekanauki.pl/articles/703326.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cryosphere
climate warming
sea ice
glacier dynamics
sea level rise
Opis:
Scale of changes of particular components of cryosphere due to global warming is presented. Cryosphere diminishes its spatial extend and the total volume of all kinds of ice is reduced. The Arctic sea ice cover has recently diminished most intensely. It reached its minimal extend (4.28 mln km2) in September 2007. One expects accelerated disintegration of sea ice of the Arctic as a result of coadjuvancy of oceanic and atmospheric factors. In consequence, more intense warming of climate coming from warmer ocean water is predicted in the Arctic basin. Increase of melting of glaciers during the last three decades results in decrease of their extend and thickness. Additionally, more meltwater is reaching bed of glaciers and is accelerating their flow velocity due to faster basal sliding. Such processes result in more intense breaking off the icebergs from fronts of glaciers terminating into the sea. Dynamic response of Greenland outlet tidewater glaciers has been detected after 2000 and it affects significantly global ocean level rise by ca 0.5 mm/yr. The Antarctic Ice Sheet is actually only insignificantly reacting to global warming. The paper discusses possible scenarios of the consequences of dynamic reaction of the West Antarctic Ice Sheet for increasing warming and slow sea level rise. Permafrost is reacting in a less distinct but detectable scale. The paper is giving not only description of consequences of climate warming for cryosphere, important impact of its spatial extend and features on atmosphere and oceans are considered either. A series of positive feedacks between  warming climate and cryosphere are listed. Described evolution of cryosphere is suggesting that distinct trend of climate warming is irreversible for the next centuries. One can also expect systematic rise of global ocean level as the consequence of glacier melting and dynamic transfer of ice masses based on land to the sea.
Źródło:
Nauka; 2008, 3
1231-8515
Pojawia się w:
Nauka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Holocene climate dynamics in Sumba Strait, Indonesia: a preliminary evidence from high resolution geochemical records and planktonic foraminifera
Autorzy:
Putra, Purna Sulastya
Nugroho, Septriono Hari
Powiązania:
https://bibliotekanauki.pl/articles/2024720.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
climate dynamics
planktonic foraminifera
Holocene deep-sea sediment
Sumba Strait
Opis:
The dynamics of climatic conditions during the Holocene in the Sumba Strait is not well known, compared with in the Indian Ocean. The aim of this paper is to identify the possible Holocene climate dynamics in Sumba Strait, eastern Indonesia by using deep-sea core sediments. A 243 cm core was taken aboard RV Baruna Jaya VIII during the Ekspedisi Widya Nusantara 2016 cruise. The core was analyzed for elemental, carbonate and organic matter content, and abundance of foraminifera. Based on geochemical and foraminifera data, we were able to identify at least six climatic changes during the Holocene in the Sumba Strait. By using the elemental ratio of terrigenous input parameter, we infer to interpret that the precipitation in the Sumba Strait during the Early Holocene was relatively higher compared with the Mid to Late Holocene.
Źródło:
Studia Quaternaria; 2020, 37; 91-99
1641-5558
2300-0384
Pojawia się w:
Studia Quaternaria
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Field study of film spreading on a sea surface
Autorzy:
Korinenko, A.E.
Malinovsky, V.V.
Powiązania:
https://bibliotekanauki.pl/articles/49188.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
oil spill
film spreading
sea surface
sea pollution
field study
coastal zone
Baltic Sea
wind speed
temporal dynamics
hydrometeorological parameter
Źródło:
Oceanologia; 2014, 56, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of propeller emergence on hull, propeller, engine, and fuel consumption performance in regular head waves
Autorzy:
Ghaemi, Mohammad Hossein
Zeraatgar, Hamid
Powiązania:
https://bibliotekanauki.pl/articles/32898210.pdf
Data publikacji:
2022
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship dynamics
ship propulsion system
propeller ventilation
propeller emergence
sea waves
Opis:
In this study, the impact of propeller emergence on the performance of a ship (speed), propeller (thrust, torque, and RPM), a diesel engine (torque and RPM) and fuel consumption are analysed under severe sea conditions. The goal is to describe the variation in the system variables and fuel consumption rather than analysing the motion of the ship or the phenomenon of propeller ventilation in itself. A mathematical model of the hull, propeller, and engine interactions is developed in which the propeller emergence is included. The system parameters are set using model experiments, empirical formulae, and available data for the engine. The dynamic response of the system is examined in regular head waves under submerged and emerged conditions of the propeller. The pulsatility and the extent of variation of 20 selected variables for the coupled system of hull, propeller, and engine are elaborated using quantitative and qualitative terms and absolute and relative scales. The simulation begins with a ship moving on a straight path, in calm water, with a constant speed for the ship, propeller and engine under steady conditions. The ship then encounters regular head waves with a known time series of the total resistance of the ship in waves. Large motions of the ship create propeller emergence, which in turn reduces the propeller thrust and torque. This study shows that for a specific ship, the mean ship speed, shaft angular velocity, and engine power were slightly reduced in submerged conditions with respect to calm water. We compared the mean values of the variables to those in the emerged condition, and found that the shaft angular velocity was almost the same, the ship speed was considerably reduced, and the engine power significantly dropped with respect to calm water. The ratios of the amplitude of fluctuation to the mean (Amp/Mean) for the ship speed and angular velocity of the shaft under both conditions were considerable, while the Amp/Mean for the power delivered by the engine was extremely high. The outcomes of the study show the degree of influence of propeller emergence on these variables. We identify the extent of each change and categorise the variables into three main groups based on the results.
Źródło:
Polish Maritime Research; 2022, 4; 56-76
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
State equations in the mathematical model of dynamic behaviour of multihull floating unit
Autorzy:
Królicka, A.
Powiązania:
https://bibliotekanauki.pl/articles/259453.pdf
Data publikacji:
2010
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
dynamics of multihull floating unit
sea waves
stochastical processes
wave spectra
Opis:
This paper concerns dynamic behaviour of multihull floating unit of catamaran type exposed to excitations due to irregular sea waves. Dynamic analysis of multihull floating unit necessitates, in its initial stage, to determine physical model of the unit and next to assume an identified mathematical model. Correctly elaborated physical models should contain information on the basis of which a mathematical model could be built. Mathematical models describe mutual relations between crucial quantities which characterize a given system in time domain. The dynamic analysis of multihull unit was performed under assumption that the unit’s model has been linear and exposed to action of irregular sea waves. Mathematical model of such dynamic system is represented by state equations. The formulated equations take into account encounter of head wave which generates symmetrical motions of the unit, i.e. surge, heave and pitch. For solving the equations the following three wave spectra were taken into consideration: - ISSC (International Ship Structures Congress) spectrum - Pierson-Moskowitz spectrum - Paszkiewicz spectrum.
Źródło:
Polish Maritime Research; 2010, 1; 33-38
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polish coastal dunes : affecting factors and morphology
Autorzy:
Łabuz, T. A.
Powiązania:
https://bibliotekanauki.pl/articles/294657.pdf
Data publikacji:
2013
Wydawca:
Stowarzyszenie Geomorfologów Polskich
Tematy:
dune coast
dune types
dune dynamics
factors impact
Polish Baltic Sea coast
Opis:
This article describe Polish coastal dunes and the factors influencing their development. The Polish coast is 500 km long and mainly exposed for a northerly direction. It is a part of the southern Baltic shore. The Polish coast is composed of mostly loose sand, till and peat. Because the coast hardiness is so weak, it is under constant threat from storm surges as well as human impact caused by rapid infrastructure development and the coastal protection measures put in place to try and protect it. These protection measures destabilize the natural coast dynamics and rebuilding process. Almost 85% of the shoreline is built up by sandy aeolian deposits and covered by different dune types. Among them are typical foredunes or inland dunes in eroded coastal areas. The second type of dune coasts are built up by land dunes, which appear on the coast as a result of sea erosion causing land regression. Sometimes dunes can be found over moraine deposits or in front of moraine old cliffs. Nowadays these habitats are heavily threatened by storm surges and human activity. In some places there is an accumulation that leads to new ridge developments. This article describes these issues with an emphasis on the present dynamics of Poland’s coastal areas.
Źródło:
Landform Analysis; 2013, 22; 33-59
1429-799X
Pojawia się w:
Landform Analysis
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Virtual ship’s roll decay test with the use of CFD technique
Autorzy:
Krata, P.
Jachowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/243570.pdf
Data publikacji:
2016
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
sea transport
ship stability
roll simulation
roll decay test
computational fluid dynamics
Opis:
Since safety of navigation is related to the stability performance of a ship, the transverse stability is routinely calculated and measured. One of the crucial experimental approach is a roll decay test. Although, an obtained result of the roll decay test carried out on the full-scale ship needs to be compared to a benchmark enabling an estimation of the relevant stability. Nowadays such a benchmark is just based on the simplified GM-based IMO-recommended formula. This research aims at the more sophisticated method of ship’s natural period of roll estimation and thus her stability assessment. The CFD (computational fluid dynamics) technique is applied and the result of the free roll simulation is compared to the solution of a roll equation. The one degree-of-freedom roll equation is applied with regard to the nonlinear ship righting moment and the nonlinear damping moment obtained according to Ikeda’s method. The six degrees-of-freedom simulation of ship’s roll decay test was carried out by the use of FlowVision code utilizing the Reynolds-averaged Navier–Stokes equation with regard to the turbulent flows based on the eddy viscosity concept. The semi-empirical k-ε turbulence model was applied. Thereby, the CFD-based approach allows to get rid of any assumptions regarding the value of the damping coefficient, which is an advantage over the roll equation based approach.
Źródło:
Journal of KONES; 2016, 23, 2; 215-221
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Danger of pollution of the water area due to the peculiarities of the coastal dynamics of the temryuk gulf of the azov sea
Autorzy:
Bogdanov, N.
Paranina, A. N.
Paranin, R.
Powiązania:
https://bibliotekanauki.pl/articles/116185.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
pollution of the water area
temryuk gulf
azov sea
peculiarities of coastal dynamics
kerch strait
coastal dynamics
coastal Zone
ecology
Opis:
Danger of pollution of water areas of the Sea of Azov and the Kerch Strait from possible technogenic catastrophes is diagnosed as a result of comparison of wind power calculations and the current state of coast of the gulf. Ideas of a uniform West Temryuk stream of deposits are disproved. Three dynamic systems in the east and in the center of a coastal arch and the unidirectional alongshore stream of pollutants and energy in the western segment of the Temryuk gulf are revealed.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2018, 12, 1; 167-172
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
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