mariana panaitescu | Constanta Maritime University (original) (raw)
Papers by mariana panaitescu
Journal of Marine Technology and Environment, Apr 1, 2024
Journal of marine technology and environment, Sep 30, 2023
Journal of Marine Technology and Environment, Apr 1, 2024
Journal of marine technology and environment, Apr 1, 2023
One of the main causes of accidents on board ships is fire. This is because of the presence of hi... more One of the main causes of accidents on board ships is fire. This is because of the presence of high temperature, the excess quantity of flammable oil and other combustible materials. A ship is fitted with various types of fire retardant and firefighting equipment so as to fight any kind of fire and extinguish it as soon as possible before it turns into a major catastrophic situation. Purpose: This paper presents the crisis management on ship's firefighting plant, Technical data for firefighting plant with foam, Fault Tree Analysis data, Fault tree block diagram, Failure probability and basic events of fault tree, The equations of fire analysis, The method of simulation, The simulation of a fire incident in the firefighting plant, for a ship named "Mamola Defender" which is a vessel that provides the supply of marine drilling platforms. The results are: Foam firefighting plant diagram, Locations for firefighting systems, Fire Control and Safety Plans, Fault tree block diagram, The values of probabilities, The relationship between input and output events. The results of simulation for a scenario are: radiant heat distribution of a jet fire, the heat flux, the temperature distribution on different stage of fire, the flame propagations. Conclusions: The methods which used for simulation present a possible fire incident in a plant with many hazardous materials. This method of simulation is useful to assistance plant owners and operators in different events of emergency situations. This methodology is useful to prevent human casualties and important structures.
Journal of marine technology and environment, Apr 1, 2023
Centrifugal pumps are most commonly used pumping devices in industry their being fit for pumping ... more Centrifugal pumps are most commonly used pumping devices in industry their being fit for pumping water. There are several types of centrifugal pumps, their differences in construction is due to their size and how cloggy the pumped water is. In the paper it was simulated a 2D centrifugal pump of small size used in daily activities. The simulation, performed with CFD (ANSYS-Fluent), was made for different inlet velocities of water. Different parameters, such as inlet pressure, outlet pressure, maximum velocity and flow rate, were calculated and graphically represented against inlet velocity. Also, graphical representation of pressure distribution and velocity distribution inside the impeller were presented for a better comprehension of the physical phenomena.
The purpose of this paper is to study the response time of SMA Sunny Tripower 5.5 inverters. Mate... more The purpose of this paper is to study the response time of SMA Sunny Tripower 5.5 inverters. Material and method: The photovoltaic generator consists of 21 polycrystalline photovoltaic panels totaling 5000 W, which directly feeds an STP 500TL-20-5.5kW Sunny Tripower grid inverter. Experimental research was conducted to test the possibility of using these inverters designed for solar systems coupled with wind turbines. As MPPT (maximum power point traking) inverters used for the above purpose, and delivering voltage to the national grid, they have an operating algorithm that allows them to adapt the impedance so that the group of photovoltaic panels delivers maximum power, indifferent to and the angle of incidence of the solar panels. The maximum voltage at which the panels work is 1000V, which allows the insertion of a large number of panels on the same string (virtually 1000/42=241000/42 = 241000/42=24 monocrystalline panels or 1000/37=271000/37 =271000/37=27 polycrystalline panels). The algorithm mentioned above probes the power curve at various impedances, and then positions itself on the impedance at which the calculated power was the maximum. After a while, the process is resumed, since it is possible that the power received by the Sun panels has changed. The same algorithm is also respected by wind turbine inverters, with the observation that the sweep of the power curve and the positioning to the maximum value takes much less. This is necessary because the value of the wind speed is much faster than the sun. In addition, the safety of the turbine requires this, as it could lead to a wind turbulence. In conclusion, SMA Sunnny Tripower inverters are very slow in terms of loading and calculating the optimal operating point.
Journal of marine technology and environment, 2015
The paper presents a computer simulation of an emergency situation generated from an oil spill, i... more The paper presents a computer simulation of an emergency situation generated from an oil spill, inside Odessa Harbor, using the software POTENTIAL INCIDENT SIMULATOR EVALUATION AND CONTROL SYSTEM (Pisces II), who it is especially designed for assessing the consequences of oil pollution on sea water.
The paper deals with the analysis of energy consumption and power quality in wastewater treatment... more The paper deals with the analysis of energy consumption and power quality in wastewater treatment plants, during the operation of air blowers optimized for monitoring the level of oxygen in the bioreactor. The airblowers' consumption is over 68% in energy consumption of wastewater treatment plant. This consumption optimization was done using sensors of the level of oxygen in the bioreactor that partial closure for command of airblowers, maintaining oxygen levels between 1.5 and 2.5%. By closing the discharge of airblowers it reduce the air flow, the rotation frequency of airblower and its consumption. The current absorbed during the operation of these airblowers shows important harmonics.
TransNav: International Journal on Marine Navigation and Safety of Sea Transportation, 2014
IOP conference series, Sep 11, 2020
TransNav: International Journal on Marine Navigation and Safety of Sea Transportation, 2023
International Journal of Modern Manufacturing Technologies, Dec 20, 2022
In this paper are presented the results obtained from a simulation of a pollution situation with ... more In this paper are presented the results obtained from a simulation of a pollution situation with crude oil products and the efficiency of the use of hydrocarbon recovery systems. In the event of major pollution accidents, in which the oil moves and touches the sandy drum, the only way of disposing is to load the polluted sand and to bring another in place, very costly and difficult operation. So, recovering a large amount of oil offshore is highly recommended. The phenomenon that governess the dynamics of pollution has been simulated using CFD (Computer Fluid Dynamics) and involves as follows:-In the first phase, the oil stain extends as the surface and thinning as thickness (thickness);-In the second phase, the mixing of hydrocarbon with water occurs, and the mixture becomes more and more difficult and no longer floats but moves immerse, but not less dangerous for the marine flora/fauna. This second phenomenon is favored by the state of the sea (the excitement of the water due to the waves). At the same time part of the hydrocarbon is volatile in the air, proportional with the temperature of water and air. Results of simulation are: a) the evolution of the quantity of petroleum product discharged during the simulation; b) the evolution of the quantity of evaporated petroleum product; c) the variation of the maximum thickness of the oil product film; d the variation of polluted surface; e) the variation of the quantity of petroleum product recovered; f) minimizing the risks of pollution by simulating scenarios with PISCES II software. The simulations on the movement and evolution of the oil film on the water surface are necessary for assessing the environmental impact, assessing the response time of the authorities in emergencies, assessing the situation, establishing The most sustainable strategies for limiting the scattering and isolation of petroleum products and the use of the most appropriate methods of response for the removal of petroleum products from the surface of the sea water or the shoreline.
Journal of marine technology and environment, 2016
Journal of marine technology and environment, 2015
In this paper it is presented a computer simulation for a possible prediction of an oil slick nea... more In this paper it is presented a computer simulation for a possible prediction of an oil slick near Burgas Harbor. The simulation it is carried out using POTENTIAL INCIDENT SIMULATOR EVALUATION AND CONTROL SYSTEM (Pisces II) which is a software, especially designed for assessing the consequences of oil pollution on sea water. PISCES is an incident response simulator designed for preparing and conducting command centre exercises and area drills. The application is developed to support exercises focusing on oil spill response. The model takes into account the main physicochemical processes occurring in the oil slick, which include evaporation, dispersion, emulsification and viscosity variation. Simulation is carried out with regard to the following environment factors: coastline, field of currents, weather, sea state, ice conditions and environmentally sensitive areas. In addition, models of response resource application including booming and recovery have been developed.
IOP Conference Series: Materials Science and Engineering, 2018
This paper focuses on the study of local vibration occurring in the structure of the ship's navig... more This paper focuses on the study of local vibration occurring in the structure of the ship's navigation bridge wings. Research and methods: The modal shapes and own frequencies of this wings, that are designed like beam type structures with different lengths and sustaining angles, are determined with the Finite Element Analysis (FEA) in the FEMAP v11.2 software. The test patterns are [00-00] and [20-45]. The purpose of the modal analysis is to determine the shapes of own modes of vibration and their frequencies, from this we can get information about the resonance frequencies and how it can affect the structure. By changing the construction materials defined in modal analysis from SAE-AISI 1025 Carbon Steel to Grade 23 Titanium, the results obtaining are comparing. Results: From the analysis of these models we can deduct a visible decrease in natural frequency of structures with the support element, in comparison with the structure without support. We can see that natural frequencies obtained by finite element method are superior to those obtained by analytical methods. Also, we can see a visible decrease in the own frequencies of the titanium structures compared to the steel ones.
Advances in Marine Navigation, 2013
Journal of Marine Technology and Environment, Apr 1, 2024
Journal of marine technology and environment, Sep 30, 2023
Journal of Marine Technology and Environment, Apr 1, 2024
Journal of marine technology and environment, Apr 1, 2023
One of the main causes of accidents on board ships is fire. This is because of the presence of hi... more One of the main causes of accidents on board ships is fire. This is because of the presence of high temperature, the excess quantity of flammable oil and other combustible materials. A ship is fitted with various types of fire retardant and firefighting equipment so as to fight any kind of fire and extinguish it as soon as possible before it turns into a major catastrophic situation. Purpose: This paper presents the crisis management on ship's firefighting plant, Technical data for firefighting plant with foam, Fault Tree Analysis data, Fault tree block diagram, Failure probability and basic events of fault tree, The equations of fire analysis, The method of simulation, The simulation of a fire incident in the firefighting plant, for a ship named "Mamola Defender" which is a vessel that provides the supply of marine drilling platforms. The results are: Foam firefighting plant diagram, Locations for firefighting systems, Fire Control and Safety Plans, Fault tree block diagram, The values of probabilities, The relationship between input and output events. The results of simulation for a scenario are: radiant heat distribution of a jet fire, the heat flux, the temperature distribution on different stage of fire, the flame propagations. Conclusions: The methods which used for simulation present a possible fire incident in a plant with many hazardous materials. This method of simulation is useful to assistance plant owners and operators in different events of emergency situations. This methodology is useful to prevent human casualties and important structures.
Journal of marine technology and environment, Apr 1, 2023
Centrifugal pumps are most commonly used pumping devices in industry their being fit for pumping ... more Centrifugal pumps are most commonly used pumping devices in industry their being fit for pumping water. There are several types of centrifugal pumps, their differences in construction is due to their size and how cloggy the pumped water is. In the paper it was simulated a 2D centrifugal pump of small size used in daily activities. The simulation, performed with CFD (ANSYS-Fluent), was made for different inlet velocities of water. Different parameters, such as inlet pressure, outlet pressure, maximum velocity and flow rate, were calculated and graphically represented against inlet velocity. Also, graphical representation of pressure distribution and velocity distribution inside the impeller were presented for a better comprehension of the physical phenomena.
The purpose of this paper is to study the response time of SMA Sunny Tripower 5.5 inverters. Mate... more The purpose of this paper is to study the response time of SMA Sunny Tripower 5.5 inverters. Material and method: The photovoltaic generator consists of 21 polycrystalline photovoltaic panels totaling 5000 W, which directly feeds an STP 500TL-20-5.5kW Sunny Tripower grid inverter. Experimental research was conducted to test the possibility of using these inverters designed for solar systems coupled with wind turbines. As MPPT (maximum power point traking) inverters used for the above purpose, and delivering voltage to the national grid, they have an operating algorithm that allows them to adapt the impedance so that the group of photovoltaic panels delivers maximum power, indifferent to and the angle of incidence of the solar panels. The maximum voltage at which the panels work is 1000V, which allows the insertion of a large number of panels on the same string (virtually 1000/42=241000/42 = 241000/42=24 monocrystalline panels or 1000/37=271000/37 =271000/37=27 polycrystalline panels). The algorithm mentioned above probes the power curve at various impedances, and then positions itself on the impedance at which the calculated power was the maximum. After a while, the process is resumed, since it is possible that the power received by the Sun panels has changed. The same algorithm is also respected by wind turbine inverters, with the observation that the sweep of the power curve and the positioning to the maximum value takes much less. This is necessary because the value of the wind speed is much faster than the sun. In addition, the safety of the turbine requires this, as it could lead to a wind turbulence. In conclusion, SMA Sunnny Tripower inverters are very slow in terms of loading and calculating the optimal operating point.
Journal of marine technology and environment, 2015
The paper presents a computer simulation of an emergency situation generated from an oil spill, i... more The paper presents a computer simulation of an emergency situation generated from an oil spill, inside Odessa Harbor, using the software POTENTIAL INCIDENT SIMULATOR EVALUATION AND CONTROL SYSTEM (Pisces II), who it is especially designed for assessing the consequences of oil pollution on sea water.
The paper deals with the analysis of energy consumption and power quality in wastewater treatment... more The paper deals with the analysis of energy consumption and power quality in wastewater treatment plants, during the operation of air blowers optimized for monitoring the level of oxygen in the bioreactor. The airblowers' consumption is over 68% in energy consumption of wastewater treatment plant. This consumption optimization was done using sensors of the level of oxygen in the bioreactor that partial closure for command of airblowers, maintaining oxygen levels between 1.5 and 2.5%. By closing the discharge of airblowers it reduce the air flow, the rotation frequency of airblower and its consumption. The current absorbed during the operation of these airblowers shows important harmonics.
TransNav: International Journal on Marine Navigation and Safety of Sea Transportation, 2014
IOP conference series, Sep 11, 2020
TransNav: International Journal on Marine Navigation and Safety of Sea Transportation, 2023
International Journal of Modern Manufacturing Technologies, Dec 20, 2022
In this paper are presented the results obtained from a simulation of a pollution situation with ... more In this paper are presented the results obtained from a simulation of a pollution situation with crude oil products and the efficiency of the use of hydrocarbon recovery systems. In the event of major pollution accidents, in which the oil moves and touches the sandy drum, the only way of disposing is to load the polluted sand and to bring another in place, very costly and difficult operation. So, recovering a large amount of oil offshore is highly recommended. The phenomenon that governess the dynamics of pollution has been simulated using CFD (Computer Fluid Dynamics) and involves as follows:-In the first phase, the oil stain extends as the surface and thinning as thickness (thickness);-In the second phase, the mixing of hydrocarbon with water occurs, and the mixture becomes more and more difficult and no longer floats but moves immerse, but not less dangerous for the marine flora/fauna. This second phenomenon is favored by the state of the sea (the excitement of the water due to the waves). At the same time part of the hydrocarbon is volatile in the air, proportional with the temperature of water and air. Results of simulation are: a) the evolution of the quantity of petroleum product discharged during the simulation; b) the evolution of the quantity of evaporated petroleum product; c) the variation of the maximum thickness of the oil product film; d the variation of polluted surface; e) the variation of the quantity of petroleum product recovered; f) minimizing the risks of pollution by simulating scenarios with PISCES II software. The simulations on the movement and evolution of the oil film on the water surface are necessary for assessing the environmental impact, assessing the response time of the authorities in emergencies, assessing the situation, establishing The most sustainable strategies for limiting the scattering and isolation of petroleum products and the use of the most appropriate methods of response for the removal of petroleum products from the surface of the sea water or the shoreline.
Journal of marine technology and environment, 2016
Journal of marine technology and environment, 2015
In this paper it is presented a computer simulation for a possible prediction of an oil slick nea... more In this paper it is presented a computer simulation for a possible prediction of an oil slick near Burgas Harbor. The simulation it is carried out using POTENTIAL INCIDENT SIMULATOR EVALUATION AND CONTROL SYSTEM (Pisces II) which is a software, especially designed for assessing the consequences of oil pollution on sea water. PISCES is an incident response simulator designed for preparing and conducting command centre exercises and area drills. The application is developed to support exercises focusing on oil spill response. The model takes into account the main physicochemical processes occurring in the oil slick, which include evaporation, dispersion, emulsification and viscosity variation. Simulation is carried out with regard to the following environment factors: coastline, field of currents, weather, sea state, ice conditions and environmentally sensitive areas. In addition, models of response resource application including booming and recovery have been developed.
IOP Conference Series: Materials Science and Engineering, 2018
This paper focuses on the study of local vibration occurring in the structure of the ship's navig... more This paper focuses on the study of local vibration occurring in the structure of the ship's navigation bridge wings. Research and methods: The modal shapes and own frequencies of this wings, that are designed like beam type structures with different lengths and sustaining angles, are determined with the Finite Element Analysis (FEA) in the FEMAP v11.2 software. The test patterns are [00-00] and [20-45]. The purpose of the modal analysis is to determine the shapes of own modes of vibration and their frequencies, from this we can get information about the resonance frequencies and how it can affect the structure. By changing the construction materials defined in modal analysis from SAE-AISI 1025 Carbon Steel to Grade 23 Titanium, the results obtaining are comparing. Results: From the analysis of these models we can deduct a visible decrease in natural frequency of structures with the support element, in comparison with the structure without support. We can see that natural frequencies obtained by finite element method are superior to those obtained by analytical methods. Also, we can see a visible decrease in the own frequencies of the titanium structures compared to the steel ones.
Advances in Marine Navigation, 2013