The Experts below are selected from a list of 75 Experts worldwide ranked by ideXlab platform
Przemyslaw Krata - One of the best experts on this subject based on the ideXlab platform.
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3d cdf modeling of Ship s heeling moment due to liquid sloshing in tanks a case study
Journal of KONES, 2010Co-Authors: Przemyslaw Krata, J JachowskiAbstract:Modeling of liquid sloshing inside partly filled Ships’ tanks can be carried out by a variety of methods. The simplest and perhaps the less reliable is a quasi-static approach which is, however, recommended in the Intact Stability Code by the International Maritime Organization. Hence the only advantage of the static estimation of liquid sloshing is simplicity of calculations, the research into the application of CFD (Computational Fluid Dynamics) was performed in Department of Ship Operation at Gdynia Maritime University. The paper presents results of numerical simulations of a liquid sloshing phenomenon performed by means of a code Fluent. The research was focused on a computation of the heeling moment affecting stability of a vessel, especially on the dynamic effects, which are omitted in obligatory intact Ship’s stability regulations nowadays. The computed distributions of dynamic pressures on tank walls were carried out for large oscillation amplitude which is characteristic for stormy sea conditions. All the simulations were computed in 3D mode and they provide high accuracy results. A case study described in the paper enables realistic comparison of the results of CFD liquid sloshing simulations and the simple statics-based computations. The study reveals some weaknesses of the contemporary quasi-static approach towards the free surface effect and it might be the contribution to the more sophisticated estimation of the Ship’s stability than it is achieved nowadays.
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Ship s heeling moment due to liquid sloshing in tanks 3d attitude
Journal of KONES, 2009Co-Authors: J Jachowski, Przemyslaw KrataAbstract:The matter of the paper refers to the dynamic stability of a vessel as an important factor affecting her safety at seaway. Ship’s seakeeping behaviour, which comprises the notion of her stability, is one of the researched key issues leading to the increase in understanding of the safety qualifying factors. Liquid sloshing phenomenon is a result of partly filled tank motions. As a tank moves, it supplies the energy to induce and sustain the fluid motion. The dynamic behaviour of a vessel at seaway is considerably affected by the dynamics of free liquid surfaces, therefore the influence of fluid movement taking place in partly filled tanks on the safety of Ship’s exploitation process is emphasized. The paper presents the results of the experimental research and the numerical simulation of the sloshing phenomenon. The research was focused on the computation of the heeling moment affecting the stability of a vessel, especially dynamic effects, which are omitted in obligatory intact Ship’s stability regulations nowadays. The experiment performed in the course of the research was carried out in Department of Ship Operation at Gdynia Maritime University. The unique test apparatus was designed and built. It enables to measure dynamic pressures on model tank walls for large oscillation amplitudes, which are characteristic for stormy sea conditions. The numerical simulations of liquid sloshing phenomenon, took into account the viscosity of liquid and the turbulence of considered flows. All the simulations were computed in 3D mode and they provide high accuracy results. The spatial distribution of dynamic pressures on model tank walls enables computation of heeling moment due to liquid sloshing which affects Ship’s stability. Further analysis of obtained moments was carried out. The study may be the contribution to the more sophisticated estimation of the Ship’s stability than it is achieved nowadays.
J Jachowski - One of the best experts on this subject based on the ideXlab platform.
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3d cdf modeling of Ship s heeling moment due to liquid sloshing in tanks a case study
Journal of KONES, 2010Co-Authors: Przemyslaw Krata, J JachowskiAbstract:Modeling of liquid sloshing inside partly filled Ships’ tanks can be carried out by a variety of methods. The simplest and perhaps the less reliable is a quasi-static approach which is, however, recommended in the Intact Stability Code by the International Maritime Organization. Hence the only advantage of the static estimation of liquid sloshing is simplicity of calculations, the research into the application of CFD (Computational Fluid Dynamics) was performed in Department of Ship Operation at Gdynia Maritime University. The paper presents results of numerical simulations of a liquid sloshing phenomenon performed by means of a code Fluent. The research was focused on a computation of the heeling moment affecting stability of a vessel, especially on the dynamic effects, which are omitted in obligatory intact Ship’s stability regulations nowadays. The computed distributions of dynamic pressures on tank walls were carried out for large oscillation amplitude which is characteristic for stormy sea conditions. All the simulations were computed in 3D mode and they provide high accuracy results. A case study described in the paper enables realistic comparison of the results of CFD liquid sloshing simulations and the simple statics-based computations. The study reveals some weaknesses of the contemporary quasi-static approach towards the free surface effect and it might be the contribution to the more sophisticated estimation of the Ship’s stability than it is achieved nowadays.
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Ship s heeling moment due to liquid sloshing in tanks 3d attitude
Journal of KONES, 2009Co-Authors: J Jachowski, Przemyslaw KrataAbstract:The matter of the paper refers to the dynamic stability of a vessel as an important factor affecting her safety at seaway. Ship’s seakeeping behaviour, which comprises the notion of her stability, is one of the researched key issues leading to the increase in understanding of the safety qualifying factors. Liquid sloshing phenomenon is a result of partly filled tank motions. As a tank moves, it supplies the energy to induce and sustain the fluid motion. The dynamic behaviour of a vessel at seaway is considerably affected by the dynamics of free liquid surfaces, therefore the influence of fluid movement taking place in partly filled tanks on the safety of Ship’s exploitation process is emphasized. The paper presents the results of the experimental research and the numerical simulation of the sloshing phenomenon. The research was focused on the computation of the heeling moment affecting the stability of a vessel, especially dynamic effects, which are omitted in obligatory intact Ship’s stability regulations nowadays. The experiment performed in the course of the research was carried out in Department of Ship Operation at Gdynia Maritime University. The unique test apparatus was designed and built. It enables to measure dynamic pressures on model tank walls for large oscillation amplitudes, which are characteristic for stormy sea conditions. The numerical simulations of liquid sloshing phenomenon, took into account the viscosity of liquid and the turbulence of considered flows. All the simulations were computed in 3D mode and they provide high accuracy results. The spatial distribution of dynamic pressures on model tank walls enables computation of heeling moment due to liquid sloshing which affects Ship’s stability. Further analysis of obtained moments was carried out. The study may be the contribution to the more sophisticated estimation of the Ship’s stability than it is achieved nowadays.
Gjermund Gravir - One of the best experts on this subject based on the ideXlab platform.
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emission from international sea transportation and environmental impact
Journal of Geophysical Research, 2003Co-Authors: Oyvind Endresen, Eirik Sorgard, Jostein K Sundet, Stig B Dalsoren, Ivar S A Isaksen, Tore F Berglen, Gjermund GravirAbstract:[1] Emission generated by the international merchant fleet has been suggested to represent a significant contribution to the global anthropogenic emissions. To analyze the impacts of these emissions, we present detailed model studies of the changes in atmospheric composition of pollutants and greenhouse compounds due to emissions from cargo and passenger Ships in international trade. Global emission inventories of NOx, SO2, CO, CO2, and volatile organic compounds (VOC) are developed by a bottom-up approach combining Ship-type specific engine emission modeling, oil cargo VOC vapor modeling, alternative global distribution methods, and Ship Operation data. Calculated bunker fuel consumption is found in agreement with international sales statistics. The Automated Mutual-assistance Vessel Rescue system (AMVER) data set is found to best reflect the distributions of cargo Ships in international trade. A method based on the relative reporting frequency weighted by the Ship size for each vessel type is recommended. We have exploited this modeled Ship emissions inventory to estimate perturbations of the global distribution of ozone, methane, sulfate, and nitrogen compounds using a global 3-D chemical transport model with interactive ozone and sulfate chemistry. Ozone perturbations are highly nonlinear, being most efficient in regions of low background pollution. Different data sets (e.g., AMVER, The Comprehensive Ocean-Atmosphere Data Set (COADS)) lead to highly different regional perturbations. A maximum ozone perturbation of approximately 12 ppbv is obtained in the North Atlantic and in the North Pacific during summer months. Global average sulfate loading increases with 2.9%, while the increase is significantly larger over parts of western Europe (up to 8%). In contrast to the AMVER data, the COADS data give particularly large enhancements over the North Atlantic. Ship emissions reduce methane lifetime by approximately 5%. CO2 and O3 give positive radiative forcing (RF), and CH4 and sulfate give negative forcing. The total RF is small (0.01–0.02 W/m2) and connected with large uncertainties. Increase in acidification is 3–10% in certain coastal areas. The approach presented here is clearly useful for characterizing the present impact of Ship emission and will be valuable for assessing the potential effect of various emission-control options.
A P Teixeira - One of the best experts on this subject based on the ideXlab platform.
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incorporation of human factors into Ship collision risk models focusing on human centred design aspects
Reliability Engineering & System Safety, 2016Co-Authors: Panagiotis Sotiralis, Nikolaos P Ventikos, Rainer Hamann, P Golyshev, A P TeixeiraAbstract:This paper presents an approach that more adequately incorporates human factor considerations into quantitative risk analysis of Ship Operation. The focus is on the collision accident category, which is one of the main risk contributors in Ship Operation. The approach is based on the development of a Bayesian Network (BN) model that integrates elements from the Technique for Retrospective and Predictive Analysis of Cognitive Errors (TRACEr) and focuses on the calculation of the collision accident probability due to human error. The model takes into account the human performance in normal, abnormal and critical Operational conditions and implements specific tasks derived from the analysis of the task errors leading to the collision accident category. A sensitivity analysis is performed to identify the most important contributors to human performance and Ship collision. Finally, the model developed is applied to assess the collision risk of a feeder operating in Dover strait using the collision probability estimated by the developed BN model and an Event tree model for calculation of human, economic and environmental risks.
Ali Mosleh - One of the best experts on this subject based on the ideXlab platform.
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human system concurrent task analysis for maritime autonomous surface Ship Operation and safety
Reliability Engineering & System Safety, 2020Co-Authors: Marilia Abilio Ramos, Christoph Alexande Thieme, Ingrid Bouwe Utne, Ali MoslehAbstract:Abstract Maritime Autonomous Surface Ships (MASS) are the subject of a diversity of projects and some are in testing phase. MASS will probably include operators working in a shore control center (SCC), whose responsibilities may vary from supervision to remote control, according to Level of Autonomy (LoA) of the voyage. Moreover, MASS may operate with a dynamic LoA. The strong reliance on Human-Autonomous System collaboration and the dynamic LoA should be comprised on the analysis of MASS to ensure its safety; and are shortcomings of current methods. This paper presents the Human-System Interaction in Autonomy (H-SIA) method for MASS collision scenarios, and illustrates its application through a case study. H-SIA consists of an Event Sequence Diagram (ESD) and a concurrent task analysis (CoTA). The ESD models the scenario in a high level and consists of events related to all system's agents. The CoTA is a novel method to analyse complex systems. It comprises of Task Analysis of each agent, which are preformed concurrently, and uses specific rules for re-description. The H-SIA method analyses the system as whole, rather than focus on each component separately, allowing identification of dependent tasks between agents and visualization of propagation of failure between the agents’ tasks.