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Volume 224 (2022): Edizione 1 (March 2022)

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Volume 219 (2019): Edizione 4 (December 2019)

Volume 218 (2019): Edizione 3 (September 2019)

Volume 217 (2019): Edizione 2 (June 2019)

Volume 216 (2019): Edizione 1 (March 2019)

Volume 215 (2018): Edizione 4 (December 2018)

Volume 214 (2018): Edizione 3 (September 2018)

Volume 213 (2018): Edizione 2 (June 2018)

Volume 212 (2018): Edizione 1 (March 2018)

Volume 211 (2017): Edizione 4 (December 2017)

Volume 210 (2017): Edizione 3 (September 2017)

Volume 209 (2017): Edizione 2 (June 2017)

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Volume 206 (2016): Edizione 3 (September 2016)

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Volume 204 (2016): Edizione 1 (March 2016)

Dettagli della rivista
Formato
Rivista
eISSN
2720-4286
Pubblicato per la prima volta
30 Mar 2016
Periodo di pubblicazione
1 volta all'anno
Lingue
Inglese

Cerca

Volume 222 (2020): Edizione 3 (September 2020)

Dettagli della rivista
Formato
Rivista
eISSN
2720-4286
Pubblicato per la prima volta
30 Mar 2016
Periodo di pubblicazione
1 volta all'anno
Lingue
Inglese

Cerca

5 Articoli
Open Access

Controlling the Operation of a Ship’s Electric Power Supply Using Fuzzy Controllers

Pubblicato online: 23 Oct 2020
Pagine: 1 - 13

Astratto

Abstract

The paper presents dynamical models of controlling voltage and frequency of ship’s electric supply set. The simulation model of synchronous generator, implemented in Matlab/Simulink, was described. For the developed simulation model, developed control systems using fuzzy controllers type P and PD were presented. Simulation research for resistance, inductive and capacitive loads were carried out for these regulators. Sample results of simulation tests are presented in the form of voltage waveforms at the output of the generator and rotational speed of the internal combustion engine for various load conditions. The conducted tests allow to assess the quality of the control process using fuzzy controllers and thus ensure the selection of the optimal solution.

Parole chiave

  • Control
  • fuzzy controller
  • electric power supply
Open Access

The Effect on Constant Heel on Circulation of a Vessel Calculated on the Basis of Investigations of M/S “Ziemia Zamojska” Model

Pubblicato online: 23 Oct 2020
Pagine: 14 - 28

Astratto

Abstract

The article presents modeling research on the M/S “Ziemia Zamojska” reduced model, carried out in an open fresh water area by a team of employees of the Department of Operating of Floating Vessels, Polish Naval Academy, Gdynia. The research involved circulating the model with constant angle of heel on the selected side, and the main engine set to full speed ahead. Using a real ship to carry this type of investigations is risky. It may lead to some failures like e.g. rudder failure, steering gear malfunction, overload and in some circumstances even main engine seizure. For this reason, ships are not tested with the rudder put to starboard or to port at the full speed ahead setting, even during a “Crash Stop” maneuver. However, based on the analysis of accidents at sea, and practical experience, it appears that during real operating conditions of vessels, there may occur situations when, for the sake of safety, the maneuver mentioned above must be carried out. Therefore, the authors had to conduct model tests of a floating vessel for the described case of ship operation

Parole chiave

  • Ship maneuvering
  • tests of maneuvering properties
  • reduction model
Open Access

Nonhomogeneus Generalisations of Poisson Process in the Modeling of Random Processes Related to Road Accidents

Pubblicato online: 23 Oct 2020
Pagine: 29 - 42

Astratto

Abstract

The stochastic processes theory provides concepts, and theorems, which allow to build the probabilistic models concerning accidents. “Counting process” can be applied for modelling the number of road, sea, and railway accidents in the given time intervals. A crucial role in construction of the models plays a Poisson process and its generalizations. The nonhomogeneous Poisson process, and the corresponding nonhomogeneous compound Poisson process are applied for modelling the road accidents number, and number of people injured and killed in Polish roads. To estimate model parameters were used data coming from the annual reports of the Polish police.

Parole chiave

  • road accident
  • nonhomogeneous Poisson process
  • nonhomogeneous compound Poisson process
Open Access

Pilot Symbol Error Re - Orthogonalization in 2 × 2 MIMO Systems of Wireless Communication

Pubblicato online: 23 Oct 2020
Pagine: 43 - 67

Astratto

Abstract

A 2×2 MIMO wireless communication system with channel estimation is simulated, in which two transmit, and two receive antennas are employed. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting. Data are modulated by coherent binary phase-shift keying, whereupon an orthogonal space-time block coding subsystem encodes information symbols by using the Alamouti code. Based on the simulation, it is ascertained a possibility to decrease the bit-error rate by substituting the Hadamard sequences for the sequences having irregular structures, and constituting the eight known orthogonal bases. Considering a de-orthogonalization caused by two any pilot sequence symbol errors, the bit-error rate is decreased by almost 2.9 %. If de-orthogonalizations are caused by two repeated indefinite, and definite pilot sequence symbol errors, the decrements are almost 16 % and 10 %, respectively. Whichever sequences are used for piloting, the 2×2 MIMO system is ascertained to be resistant to the de-orthogonalization if the frame is of 128 to 256 symbols piloted with 32 to 64 symbols, respectively.

Parole chiave

  • wireless communication
  • channel estimation
  • MIMO
  • orthogonal pilot sequences
  • bit-error rate
Open Access

Ice Drift in the Arctic Ocean

Pubblicato online: 23 Oct 2020
Pagine: 68 - 85

Astratto

Abstract

The paper presents results of research based on analysis of historical and present studies of the Arctic ice drift. Current information about Arctic ice drift comes from the scientific expedition organized by the Alfred-Wrgener-Institut Helmholtz Centre for Polar and Marine Research (AWI) from Bremerhaven (Germany) in the Arctic Ocean, as a part of the Multidiscipli-nary drifting Observatory for the Study of Arctic Climate (MOSAiC), coming from the deck of the icebreaker RV “Polarstern”. The main purpose of the article was to collect and illustrate information on the phenomenon of ice drift in the Arctic Ocean, considering data from ongoing research during the MOSAiC expedition. The average movement speed of the icebreaker RV “Polarstern” frozen in Arctic ice during the first three legs of the expedition was over 5 Nm/day, which is characteristic of the current data relating to the speed of the Arctic ice drift in the place of research. On the other hand, the article is popular science, and presents the overall characteristics of Arctic ice drift with an indication of the general directions, and speed of its movement. Ice drift speeds in the Arctic can reach exceptionally high values under favorable conditions. The drift of sea ice reaching at its intensity/intensity values close to the limit (dangerous criterion) in these extreme cases is called the “ice river”. The speed of “ice rivers” can reach up to 1–2 knots, however, in extreme conditions up to 9 knots. Based on data from the AWI, correlation points were identified between the speed of Arctic ice drift and the speed of winds and atmospheric pressure values.

Parole chiave

  • sea ice drift
  • Arctic ice drift
  • MOSAiC
5 Articoli
Open Access

Controlling the Operation of a Ship’s Electric Power Supply Using Fuzzy Controllers

Pubblicato online: 23 Oct 2020
Pagine: 1 - 13

Astratto

Abstract

The paper presents dynamical models of controlling voltage and frequency of ship’s electric supply set. The simulation model of synchronous generator, implemented in Matlab/Simulink, was described. For the developed simulation model, developed control systems using fuzzy controllers type P and PD were presented. Simulation research for resistance, inductive and capacitive loads were carried out for these regulators. Sample results of simulation tests are presented in the form of voltage waveforms at the output of the generator and rotational speed of the internal combustion engine for various load conditions. The conducted tests allow to assess the quality of the control process using fuzzy controllers and thus ensure the selection of the optimal solution.

Parole chiave

  • Control
  • fuzzy controller
  • electric power supply
Open Access

The Effect on Constant Heel on Circulation of a Vessel Calculated on the Basis of Investigations of M/S “Ziemia Zamojska” Model

Pubblicato online: 23 Oct 2020
Pagine: 14 - 28

Astratto

Abstract

The article presents modeling research on the M/S “Ziemia Zamojska” reduced model, carried out in an open fresh water area by a team of employees of the Department of Operating of Floating Vessels, Polish Naval Academy, Gdynia. The research involved circulating the model with constant angle of heel on the selected side, and the main engine set to full speed ahead. Using a real ship to carry this type of investigations is risky. It may lead to some failures like e.g. rudder failure, steering gear malfunction, overload and in some circumstances even main engine seizure. For this reason, ships are not tested with the rudder put to starboard or to port at the full speed ahead setting, even during a “Crash Stop” maneuver. However, based on the analysis of accidents at sea, and practical experience, it appears that during real operating conditions of vessels, there may occur situations when, for the sake of safety, the maneuver mentioned above must be carried out. Therefore, the authors had to conduct model tests of a floating vessel for the described case of ship operation

Parole chiave

  • Ship maneuvering
  • tests of maneuvering properties
  • reduction model
Open Access

Nonhomogeneus Generalisations of Poisson Process in the Modeling of Random Processes Related to Road Accidents

Pubblicato online: 23 Oct 2020
Pagine: 29 - 42

Astratto

Abstract

The stochastic processes theory provides concepts, and theorems, which allow to build the probabilistic models concerning accidents. “Counting process” can be applied for modelling the number of road, sea, and railway accidents in the given time intervals. A crucial role in construction of the models plays a Poisson process and its generalizations. The nonhomogeneous Poisson process, and the corresponding nonhomogeneous compound Poisson process are applied for modelling the road accidents number, and number of people injured and killed in Polish roads. To estimate model parameters were used data coming from the annual reports of the Polish police.

Parole chiave

  • road accident
  • nonhomogeneous Poisson process
  • nonhomogeneous compound Poisson process
Open Access

Pilot Symbol Error Re - Orthogonalization in 2 × 2 MIMO Systems of Wireless Communication

Pubblicato online: 23 Oct 2020
Pagine: 43 - 67

Astratto

Abstract

A 2×2 MIMO wireless communication system with channel estimation is simulated, in which two transmit, and two receive antennas are employed. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting. Data are modulated by coherent binary phase-shift keying, whereupon an orthogonal space-time block coding subsystem encodes information symbols by using the Alamouti code. Based on the simulation, it is ascertained a possibility to decrease the bit-error rate by substituting the Hadamard sequences for the sequences having irregular structures, and constituting the eight known orthogonal bases. Considering a de-orthogonalization caused by two any pilot sequence symbol errors, the bit-error rate is decreased by almost 2.9 %. If de-orthogonalizations are caused by two repeated indefinite, and definite pilot sequence symbol errors, the decrements are almost 16 % and 10 %, respectively. Whichever sequences are used for piloting, the 2×2 MIMO system is ascertained to be resistant to the de-orthogonalization if the frame is of 128 to 256 symbols piloted with 32 to 64 symbols, respectively.

Parole chiave

  • wireless communication
  • channel estimation
  • MIMO
  • orthogonal pilot sequences
  • bit-error rate
Open Access

Ice Drift in the Arctic Ocean

Pubblicato online: 23 Oct 2020
Pagine: 68 - 85

Astratto

Abstract

The paper presents results of research based on analysis of historical and present studies of the Arctic ice drift. Current information about Arctic ice drift comes from the scientific expedition organized by the Alfred-Wrgener-Institut Helmholtz Centre for Polar and Marine Research (AWI) from Bremerhaven (Germany) in the Arctic Ocean, as a part of the Multidiscipli-nary drifting Observatory for the Study of Arctic Climate (MOSAiC), coming from the deck of the icebreaker RV “Polarstern”. The main purpose of the article was to collect and illustrate information on the phenomenon of ice drift in the Arctic Ocean, considering data from ongoing research during the MOSAiC expedition. The average movement speed of the icebreaker RV “Polarstern” frozen in Arctic ice during the first three legs of the expedition was over 5 Nm/day, which is characteristic of the current data relating to the speed of the Arctic ice drift in the place of research. On the other hand, the article is popular science, and presents the overall characteristics of Arctic ice drift with an indication of the general directions, and speed of its movement. Ice drift speeds in the Arctic can reach exceptionally high values under favorable conditions. The drift of sea ice reaching at its intensity/intensity values close to the limit (dangerous criterion) in these extreme cases is called the “ice river”. The speed of “ice rivers” can reach up to 1–2 knots, however, in extreme conditions up to 9 knots. Based on data from the AWI, correlation points were identified between the speed of Arctic ice drift and the speed of winds and atmospheric pressure values.

Parole chiave

  • sea ice drift
  • Arctic ice drift
  • MOSAiC

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