Pub Date : 2021-12-13DOI: 10.5750/ijme.v158ia4.999
J. Chen, Z. Zou, M. Chen, H. M. Wang
Ships tend to maneuver in oblique motion at low speed in situations such as turning in a harbor, or during offloading, dynamic positioning and mooring processes. The maneuverability criteria proposed by IMO are valid for ships sailing with relatively high speeds and small drift angles, which are inadequate to predict ship maneuverability in low speed condition. Hydrodynamic performance of ships maneuvering at low speed is needed to know for safety issues. A CFD-based method is employed to predict the flow around an Esso Osaka bare hull model in oblique motion at low speed, where the drift angle varies from 0° to 180°. The URANS method with the SST k-ω model is used for simulating ship flows with drift angles 0°~30° and 150°~180°, and DES method for simulating ship flows with drift angles 40°~150°. Verification and validation studies are conducted for drift angles of 0° and 70°. The vortex structures at typical drift angles of 0°, 30°, 50°, 70°, 90° and 180° are analyzed. The effects of drift angle and ship speed are demonstrated.
{"title":"CFD-BASED SIMULATION OF THE FLOW AROUND A SHIP IN OBLIQUE MOTION AT LOW SPEED","authors":"J. Chen, Z. Zou, M. Chen, H. M. Wang","doi":"10.5750/ijme.v158ia4.999","DOIUrl":"https://doi.org/10.5750/ijme.v158ia4.999","url":null,"abstract":"Ships tend to maneuver in oblique motion at low speed in situations such as turning in a harbor, or during offloading, dynamic positioning and mooring processes. The maneuverability criteria proposed by IMO are valid for ships sailing with relatively high speeds and small drift angles, which are inadequate to predict ship maneuverability in low speed condition. Hydrodynamic performance of ships maneuvering at low speed is needed to know for safety issues. A CFD-based method is employed to predict the flow around an Esso Osaka bare hull model in oblique motion at low speed, where the drift angle varies from 0° to 180°. The URANS method with the SST k-ω model is used for simulating ship flows with drift angles 0°~30° and 150°~180°, and DES method for simulating ship flows with drift angles 40°~150°. Verification and validation studies are conducted for drift angles of 0° and 70°. The vortex structures at typical drift angles of 0°, 30°, 50°, 70°, 90° and 180° are analyzed. The effects of drift angle and ship speed are demonstrated.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47546946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.5750/ijme.v158ia1.969
V. Rumawas, B. Asbjørnslett
A survey of human factors on two state-of-the-art offshore supply vessels (OSVs) operating in the Norwegian Sea was performed by means of questionnaires. The purpose of the study was to examine whether human factors had been adequately addressed in ship design, how they were regarded by the crews, and whether design decisions were believed to have an effect on incidents on-board. The concept of human factors in ship design was operationalised into eight dimensions: habitability, workability, controllability, maintainability, manoeuvrability, survivability, occupational health and safety (OHS), and system safety. Inferential statistics were applied in order to draw conclusions, including means comparisons and multivariate regression analyses. The results show that human factors were given significant importance in the ship design. The level of accomplishment of human factors differs from one dimension to another. The highest satisfactory dimension was OHS and maintainability was the lowest, but still considered adequate. Design is revealed to have an impact on human factor ratings. Further, OSV design and human factor ratings are identified as having effects on particular incidents on board.
{"title":"HUMAN FACTORS ON OFFSHORE SUPPLY VESSELS IN THE NORWEGIAN SEA – AN EXPLANATORY SURVEY","authors":"V. Rumawas, B. Asbjørnslett","doi":"10.5750/ijme.v158ia1.969","DOIUrl":"https://doi.org/10.5750/ijme.v158ia1.969","url":null,"abstract":"A survey of human factors on two state-of-the-art offshore supply vessels (OSVs) operating in the Norwegian Sea was performed by means of questionnaires. The purpose of the study was to examine whether human factors had been adequately addressed in ship design, how they were regarded by the crews, and whether design decisions were believed to have an effect on incidents on-board. The concept of human factors in ship design was operationalised into eight dimensions: habitability, workability, controllability, maintainability, manoeuvrability, survivability, occupational health and safety (OHS), and system safety. Inferential statistics were applied in order to draw conclusions, including means comparisons and multivariate regression analyses. The results show that human factors were given significant importance in the ship design. The level of accomplishment of human factors differs from one dimension to another. The highest satisfactory dimension was OHS and maintainability was the lowest, but still considered adequate. Design is revealed to have an impact on human factor ratings. Further, OSV design and human factor ratings are identified as having effects on particular incidents on board.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42845047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.5750/ijme.v159ia4.1040
M. J. Núñez Sánchez, L. Pérez Rojas
Fishing is a very dangerous sea activity with a high rate of fatalities that is difficult to deal with by Maritime and Fisheries Administrations around the world. Meanwhile the Ocean Governance requires a global approach to sustainability and safety, with overarching principles governing both of them. This paper deals for the first time with the implementation of a complete methodology to assess the safety at sea, by means of a bottom-up goal based standards with safety level approach, encompassing the national regulations and using formal safety assessment as the driver in a fishing vessel fleet below 24 m in length (L). It is concluded that such methodologies are applicable, goal based regulations can be established, flexibility in the design can be provided and have the potential to be later extrapolated to holistic approaches.
{"title":"REGULATORY APPROACHES LEADING TO HOLISTIC IMPLEMENTATION IN A FISHING VESSEL FLEET LESS THAN 24 M IN LENGTH","authors":"M. J. Núñez Sánchez, L. Pérez Rojas","doi":"10.5750/ijme.v159ia4.1040","DOIUrl":"https://doi.org/10.5750/ijme.v159ia4.1040","url":null,"abstract":"Fishing is a very dangerous sea activity with a high rate of fatalities that is difficult to deal with by Maritime and Fisheries Administrations around the world. Meanwhile the Ocean Governance requires a global approach to sustainability and safety, with overarching principles governing both of them. This paper deals for the first time with the implementation of a complete methodology to assess the safety at sea, by means of a bottom-up goal based standards with safety level approach, encompassing the national regulations and using formal safety assessment as the driver in a fishing vessel fleet below 24 m in length (L). It is concluded that such methodologies are applicable, goal based regulations can be established, flexibility in the design can be provided and have the potential to be later extrapolated to holistic approaches.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48946514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.3940/rina.ijme.2011.a2.wf9tn
M. Hajiarab, M. Downie, M. Graham
This paper presents a study on viscous roll damping of a floating box-shaped vessel in the frequency domain. The application of the discrete vortex method (DVM) for calculation of the viscous roll damping in regular seas has been validated by model tests. Equivalent roll RAOs associated with a range of regular wave amplitudes are calculated to assess behaviour of the viscous roll damping in relation to incident wave amplitude linearisation. A model test is conducted using the model test facilities of the Marine Hydrodynamics Laboratory at Newcastle University to validate the applicability of the DVM in calculating the roll RAO in regular waves and to study the application of this method to irregular waves. Results of these model tests are presented in this paper.
{"title":"A STUDY ON VISCOUS ROLL DAMPING OF A BOX-SHAPED VESSEL IN THE FREQUENCY DOMAIN USING THE DISCRETE VORTEX METHOD","authors":"M. Hajiarab, M. Downie, M. Graham","doi":"10.3940/rina.ijme.2011.a2.wf9tn","DOIUrl":"https://doi.org/10.3940/rina.ijme.2011.a2.wf9tn","url":null,"abstract":"This paper presents a study on viscous roll damping of a floating box-shaped vessel in the frequency domain. The application of the discrete vortex method (DVM) for calculation of the viscous roll damping in regular seas has been validated by model tests. Equivalent roll RAOs associated with a range of regular wave amplitudes are calculated to assess behaviour of the viscous roll damping in relation to incident wave amplitude linearisation. A model test is conducted using the model test facilities of the Marine Hydrodynamics Laboratory at Newcastle University to validate the applicability of the DVM in calculating the roll RAO in regular waves and to study the application of this method to irregular waves. Results of these model tests are presented in this paper.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46921141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.5750/ijme.v152ia1.819
I. Bačkalov
The author was previously involved in the development of the risk-based stability analysis which is now further extended, and used for the safety assessment of estuary container vessels subjected to stochastic action of beam wind and irregular waves. The study was motivated by the new set of safety regulations for estuary vessels issued by Belgian authorities in cooperation with Lloyd’s Register. These regulations introduce very innovative probabilistic ideas to ship stability regulations, and therefore present a significant step forward compared to the classical approach. Still, they do not account properly some important influences, such as wind gusts and motion nonlinearities, so considerably simplify the problem. The present investigation models the vessel motion much more realistically, analyzes the influence of beam wind and beam waves on the probability of a stability failure, and argues whether simplifications proposed by the regulations were justified. It is believed that presented method is not limited to the safety of estuary vessels only, but also gives important guidelines for a more general investigation of ship safety in wind and waves.
{"title":"PROBABILISTIC SAFETY OF ESTUARY VESSELS BASED ON NONLINEAR ROLLING IN WIND AND WAVES","authors":"I. Bačkalov","doi":"10.5750/ijme.v152ia1.819","DOIUrl":"https://doi.org/10.5750/ijme.v152ia1.819","url":null,"abstract":"The author was previously involved in the development of the risk-based stability analysis which is now further extended, and used for the safety assessment of estuary container vessels subjected to stochastic action of beam wind and irregular waves. The study was motivated by the new set of safety regulations for estuary vessels issued by Belgian authorities in cooperation with Lloyd’s Register. These regulations introduce very innovative probabilistic ideas to ship stability regulations, and therefore present a significant step forward compared to the classical approach. Still, they do not account properly some important influences, such as wind gusts and motion nonlinearities, so considerably simplify the problem. The present investigation models the vessel motion much more realistically, analyzes the influence of beam wind and beam waves on the probability of a stability failure, and argues whether simplifications proposed by the regulations were justified. It is believed that presented method is not limited to the safety of estuary vessels only, but also gives important guidelines for a more general investigation of ship safety in wind and waves.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48575130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.5750/ijme.v156ia4.939
M. Yoshida, H. Kihara, H. Iwashita, M. Kanda, T. Kinoshita
The speed reduction, additional resistance or slamming caused by the large amplitude ship motions, should be completely restricted for a large fast oceangoing ship because of the strict time-punctuality and the high value of the cargo. A “Resonance-Free SWATH (RFS)”, which has negative restoring moments due to the extremely small water plane area, is introduced to minimize the motion responses. A motion control system using small fins is necessary for the RFS, which has no stability during high speed cruising. Theoretical estimations and experiments to search for the optimum values of PD control gains have been performed. Unsteady characteristics of fin-generated lift such as the time lag and the interaction among the fins and lower hulls have been measured and they are taken into account in the motion equations. Then, experiments using the RFS model with controlling fins have been carried out to validate the theoretical estimation for the motion responses of the RFS in waves. The theoretical and experimental results agree well with each other. The motion responses of the RFS in regular and irregular head waves are compared with those of other hull forms, such as a mono-hull, an ordinary SWATH and a trimaran. The clear advantage of the RFS regarding the seaworthiness has been found. In summary, the heave motion response of the RFS is reduced to 1/60 and the pitch motion becomes1/8, compared with those of the existing mono-hull ship.
{"title":"SUPERIOR SEAWORTHINESS OF A RESONANCE-FREE FAST OCEANGOING SWATH","authors":"M. Yoshida, H. Kihara, H. Iwashita, M. Kanda, T. Kinoshita","doi":"10.5750/ijme.v156ia4.939","DOIUrl":"https://doi.org/10.5750/ijme.v156ia4.939","url":null,"abstract":"The speed reduction, additional resistance or slamming caused by the large amplitude ship motions, should be completely restricted for a large fast oceangoing ship because of the strict time-punctuality and the high value of the cargo. A “Resonance-Free SWATH (RFS)”, which has negative restoring moments due to the extremely small water plane area, is introduced to minimize the motion responses. A motion control system using small fins is necessary for the RFS, which has no stability during high speed cruising. Theoretical estimations and experiments to search for the optimum values of PD control gains have been performed. Unsteady characteristics of fin-generated lift such as the time lag and the interaction among the fins and lower hulls have been measured and they are taken into account in the motion equations. Then, experiments using the RFS model with controlling fins have been carried out to validate the theoretical estimation for the motion responses of the RFS in waves. The theoretical and experimental results agree well with each other. The motion responses of the RFS in regular and irregular head waves are compared with those of other hull forms, such as a mono-hull, an ordinary SWATH and a trimaran. The clear advantage of the RFS regarding the seaworthiness has been found. In summary, the heave motion response of the RFS is reduced to 1/60 and the pitch motion becomes1/8, compared with those of the existing mono-hull ship.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48998294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.5750/ijme.v160ia2.1052
S. Sindagi, R. Vijayakumar, B. K. Saxena
The reduction of ship’s resistance is one of the most effective way to reduce emissions, operating costs and to improve EEDI. It is reported that, for slow moving vessels, the frictional drag accounts for as much as 80% of the total drag, thus there is a strong demand for the reduction in the frictional drag. The use of air as a lubricant, known as Micro Bubble Drag Reduction, to reduce that frictional drag is an active research topic. The main focus of authors is to present the current scenario of research carried out worldwide along with numerical simulation of air injection in a rectangular channel. Latest developments in this field suggests that, there is a potential reduction of 80% & 30% reduction in frictional drag in case of flat plates and ships respectively. Review suggests that, MBDR depends on Gas or Air Diffusion which depends on, Bubble size distributions and coalescence and surface tension of liquid, which in turn depends on salinity of water, void fraction, location of injection points, depth of water in which bubbles are injected. Authors are of opinion that, Microbubbles affect the performance of Propeller, which in turn decides net savings in power considering power required to inject Microbubbles. Moreover, 3D numerical investigations into frictional drag reduction by microbubbles were carried out in Star CCM+ on a channel for different flow velocities, different void fraction and for different cross sections of flow at the injection point. This study is the first of its kind in which, variation of coefficient of friction both in longitudinal as well as spanwise direction were studied along with actual localised variation of void fraction at these points. From the study, it is concluded that, since it is a channel flow and as the flow is restricted in confined region, effect of air injection is limited to smaller area in spanwise direction as bubbles were not escaping in spanwise direction.
{"title":"FRICTIONAL DRAG REDUCTION: REVIEW AND NUMERICAL INVESTIGATION OF MICROBUBBLE DRAG REDUCTION IN A CHANNEL FLOW","authors":"S. Sindagi, R. Vijayakumar, B. K. Saxena","doi":"10.5750/ijme.v160ia2.1052","DOIUrl":"https://doi.org/10.5750/ijme.v160ia2.1052","url":null,"abstract":"The reduction of ship’s resistance is one of the most effective way to reduce emissions, operating costs and to improve EEDI. It is reported that, for slow moving vessels, the frictional drag accounts for as much as 80% of the total drag, thus there is a strong demand for the reduction in the frictional drag. The use of air as a lubricant, known as Micro Bubble Drag Reduction, to reduce that frictional drag is an active research topic. The main focus of authors is to present the current scenario of research carried out worldwide along with numerical simulation of air injection in a rectangular channel. Latest developments in this field suggests that, there is a potential reduction of 80% & 30% reduction in frictional drag in case of flat plates and ships respectively. Review suggests that, MBDR depends on Gas or Air Diffusion which depends on, Bubble size distributions and coalescence and surface tension of liquid, which in turn depends on salinity of water, void fraction, location of injection points, depth of water in which bubbles are injected. Authors are of opinion that, Microbubbles affect the performance of Propeller, which in turn decides net savings in power considering power required to inject Microbubbles. Moreover, 3D numerical investigations into frictional drag reduction by microbubbles were carried out in Star CCM+ on a channel for different flow velocities, different void fraction and for different cross sections of flow at the injection point. This study is the first of its kind in which, variation of coefficient of friction both in longitudinal as well as spanwise direction were studied along with actual localised variation of void fraction at these points. From the study, it is concluded that, since it is a channel flow and as the flow is restricted in confined region, effect of air injection is limited to smaller area in spanwise direction as bubbles were not escaping in spanwise direction.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49059441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.5750/ijme.v157ia2.953
O. Uğurlu, U. Yildirim, E. Yüksekyıldız, R. Nisanci, E. Köse
This study focuses on marine accident data regarding accidents that occurred between the years 1998-2010 for ships within the oil tanker category. Data in the study include accident reports, which are recorded in the Global Integrated Shipping Information System (GISIS) and country reports. Textual accident data in the GISIS database were tabulated, thus creating a systematic database. By using accident data from this database, a marine accidents map for oil tankers was developed via the ArcGIS 10 program, the areas with the highest accident incident rates were determined, and reasons for oil tanker accidents were revealed through the assessment of factors such as accident type, accident incident number, accident scope, ship tonnage, navigational sea area type, and accident’s impacts on the environment, economy and personnel. The study showed that very high risk areas for oil tanker marine accidents include the Singapore Strait and Oresund, and high risk areas are the Bristol Channel, Suez Channel, Strait of Hormuz, Great Belt, Piraeus, Hull, İstanbul Strait, and Amsterdam, respectively. The study also established that oil tanker accidents are related to ship tonnage and navigational sea area type.
{"title":"INVESTIGATION OF OIL TANKER ACCIDENTS BY USING GIS","authors":"O. Uğurlu, U. Yildirim, E. Yüksekyıldız, R. Nisanci, E. Köse","doi":"10.5750/ijme.v157ia2.953","DOIUrl":"https://doi.org/10.5750/ijme.v157ia2.953","url":null,"abstract":"This study focuses on marine accident data regarding accidents that occurred between the years 1998-2010 for ships within the oil tanker category. Data in the study include accident reports, which are recorded in the Global Integrated Shipping Information System (GISIS) and country reports. Textual accident data in the GISIS database were tabulated, thus creating a systematic database. By using accident data from this database, a marine accidents map for oil tankers was developed via the ArcGIS 10 program, the areas with the highest accident incident rates were determined, and reasons for oil tanker accidents were revealed through the assessment of factors such as accident type, accident incident number, accident scope, ship tonnage, navigational sea area type, and accident’s impacts on the environment, economy and personnel. The study showed that very high risk areas for oil tanker marine accidents include the Singapore Strait and Oresund, and high risk areas are the Bristol Channel, Suez Channel, Strait of Hormuz, Great Belt, Piraeus, Hull, İstanbul Strait, and Amsterdam, respectively. The study also established that oil tanker accidents are related to ship tonnage and navigational sea area type.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44006731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.5750/ijme.v156ia1.918
W. Luo, C. Guedes Soares, Z. Zou
A study is presented of the effect of a pier on ship trajectories in currents. The current flow field around the pier is investigated. Experiments on ship manoeuvring and drift motion in the vicinity of a rectangular pier were carried out in a tank. Different current velocities and current angles were taken into account. The characteristics of the deviations of the ship trajectories from the initial course around the pier are investigated. Experimental findings indicate that the minimum required distance for safety navigation becomes larger with an increase of the current velocity. To obtain the details of continuous three-dimensional flow field around a pier, numerical simulation based on CFD calculations is conducted. The validity of the numerical simulation is demonstrated by comparison with experimental results.
{"title":"EXPERIMENTAL AND NUMERICAL STUDY OF THE EFFECT OF A PIER ON SHIP TRAJECTORIES IN CURRENTS","authors":"W. Luo, C. Guedes Soares, Z. Zou","doi":"10.5750/ijme.v156ia1.918","DOIUrl":"https://doi.org/10.5750/ijme.v156ia1.918","url":null,"abstract":"A study is presented of the effect of a pier on ship trajectories in currents. The current flow field around the pier is investigated. Experiments on ship manoeuvring and drift motion in the vicinity of a rectangular pier were carried out in a tank. Different current velocities and current angles were taken into account. The characteristics of the deviations of the ship trajectories from the initial course around the pier are investigated. Experimental findings indicate that the minimum required distance for safety navigation becomes larger with an increase of the current velocity. To obtain the details of continuous three-dimensional flow field around a pier, numerical simulation based on CFD calculations is conducted. The validity of the numerical simulation is demonstrated by comparison with experimental results.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43656285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.5750/ijme.v161ia3.1095
Shaik Yaseen Baba, P. Avadhani
For the cost effective & safe operation of ships and other marine assets it is mandatory to develop software solution tool which helps in timely maintenance with priority based to avoid both financial losses and operational downtime. Our idea is to propose concept to develop combined protection mechanisms system for Planned Maintenance system. The research is IDENTIFYING AND SCHEDULING DDOS-APPLICATION LAYER ATTACKS on onboard systems. Countering Distributed Denial of Service (DDOS) attacks are becoming ever more challenging with the vast resources and techniques increasingly available to attackers. In this paper, we consider sophisticated attacks that are protocol- compliant, non-intrusive, utilize legitimate. Application-layer requests to overwhelm system resources. We characterize application layer resource attacks on the basis of the application workload parameters that they exploit. Request flooding, asymmetric, repeated one-shot. To protect marine software-based servers from these attacks, we propose a counter-mechanism that consists of a suspicion assignment mechanism and a DDOS-resilient scheduler, DDOS Shield. In contrast to prior work, our suspicion mechanism assigns a continuous value as opposed to a binary measure to each client session, and the scheduler utilizes these values to determine if and when to schedule a session’s requests. This will be done through an integrated working of PMS and Inventory. PMS and Inventory, while performing definite tasks independently, will seamlessly integrate with each other. Further the installations will reside in the vessel, office and other office nodes, where information can be viewed and updated depending on your network of vessels. In office, the Inventory-PMS package will function in a client –server mode and in a single terminal on the ship with LAN for the purpose of accessing Internet. All the database updating and back-up maintenance shall be shown into the system to enable the user to do the database management without incurring exorbitant annual maintenance bills, which normally comes with all similar systems in the market.
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