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1
Content available remote The distribution and tapping tidal energy
100%
Kowalik Z.
Oceanologia
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2004
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tom No. 46 (3)
291-331
EN
Tidal power along tidal shores has been used for centuries to run small tidal mills. Generating electricity by tapping tidal power proved to be very successful only in the last century through the tidal power plant constructed in 1967 in La Rance, France. This used a large barrier to generate the sea level head necessary for driving turbines. Construction of such plants evolved very slowly because of prohibitive costs and concerns about the environmental impact. Developments in the construction of small, efficient and inexpensive underwater turbines admit the possibility of small scale operations that will use local tidal currents to bring electricity to remote locations. Since the generation of such electricity is concerned with the tidal energy in local water bodies, it is important to understand the site-specific energy balance, i.e., the energy flowing in through open boundaries, and the energy generated and dissipated within the local domain. The question is how to tap the tidal energy while keeping possible changes in the present tidal regimes to a minimum. The older approach of constructing barrages may still be quite useful in some locations. The basics of such tidal power plants constructed in a small bay are analyzed in order to understand the principal parameter for tidal plant evaluation, i.e., the power produced. The new approach is to place turbines - devices similar to windmills - in the pathway of tidal currents. Theoretically, the amount of power available by such turbines for electricity generation is proportional to the water density and velocity cubed of the tidal flow. The naturally dissipated tidal power due to bottom friction forces is also proportional to the cube of the velocity. Because of this similarity, the exploitation of tidal energy can be directed to reinvesting the naturally dissipated power into tidal power for the generation of electricity. This approach to tidal power exploitation is better tuned towards preservation of the natural tidal regime. To answer the many questions related to tidal regime changes, it is important to develop a new branch of tidal dynamics which will help to better understand the interaction between a natural tidal regime and future changes caused by tapping into tidal energy.
2
Content available remote Analiza błędu w modelu matematycznym przetwornika elektromechanicznego wykorzystującym równania Hamiltona
63%
Burlikowski W. , Kowalik Z.
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tom Nr 4(104)
131--136
PL
W artykule przedstawiono metodykę analizy błędu w modelu matematycznym przetwornika elektromechanicznego, wykorzystującym równania Hamiltona w opisie przemiany elektromechanicznej. Jako podstawową wielkość w algorytmie obliczeniowym użyto koenergię pola magnetycznego Ecm. Wykorzystano w tym celu jednoznaczność określenia wartości koenergii dla danej wartości zmiennych stanu, wynikającą z pominięcia w modelu prądów wirowych oraz zjawiska histerezy.
EN
The paper presents a methodology of error analysis in mathematical model of an electromechanical actuator using Hamiltonian equations in the description of energy conversion. As the basic quantity in numerical algorithm the coenergy of magnetic field Ecm is employed. The reason for application of coenergy as a state function is the explicitness of its value for a given set of state variables, resulting from neglecting Eddy currents and hysteresis phenomenon in the model.
3
Influence of water exchange between the Baltic Sea and the North Sea on storm surges in the Baltic
63%
Chilicka Z. , Kowalik Z.
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tom 19
4
Content available remote Error analysis in mathematical model of electromechanical actuator using Hamiltonian equations
63%
Burlikowski W. , Kowalik Z.
Czasopismo Techniczne. Elektrotechnika
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2015
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tom Y. 112, iss. 1-E
119--128
EN
This paper presents a methodology of error analysis in a mathematical model of an electromechanical actuator using Hamiltonian equations in the description of energy conversion. As the basic quantity in numerical algorithms, the coenergy of magnetic field Ecm is employed. The reason for the application of coenergy as a state function is the explicitness of its value for a given set of state variables, resulting from neglecting eddy currents and hysteresis phenomenon in the model.
PL
W artykule przedstawiono metodykę analizy błędu w modelu matematycznym przetwornika elektromechanicznego wykorzystującym równania Hamiltona w opisie przemiany elektromechanicznej. Jako podstawowej wielkości w algorytmie obliczeniowym użyto koenergii pola magnetycznego Ecm. Wykorzystano w tym celu jednoznaczność określenia wartości koenergii dla danej wartości zmiennych stanu, wynikającą z pominięcia w modelu prądów wirowych oraz zjawiska histerezy.
5
Content available Development of a topology-based current-flux characteristic approximation in a Hamiltonian model of a reluctance machine
63%
Burlikowski W. , Kowalik Z.
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tom Vol. 64, nr 2
277--289
EN
The paper presents an algorithm for the construction of an approximation of a highly nonlinear current-flux characteristic of a synchronous reluctance machine. Such an approximation is required in a Hamiltonian model of an electric machine and the constructed approximation is suited to be used in such a model. It employs a simplicial approximation based on irregular points sets in the spaces of currents and fluxes. The sets are constructed by the iterative insertion of new points. Initially the sets contain an arbitrarily small number of elements. The insertion is based on an approximation error calculation. Based on the sets containing possibly small number of elements, the proposed procedure leads to smooth and precise approximation. Due to the nonlinearity of the approximated characteristics, ambiguities can occur. A method for the triangulation refinement of the sets of currents and fluxes that eliminates them is also presented. In the paper, a reluctance machine model using the constructed approximation is described and compared with a model using the approximation based on regular sets.
6
Consltruction of a numerical model of storm surges with a refined grid
51%
Chilicka Z. , Kowalik Z. , Wierzbicki Z.
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tom 16
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