rss_2.0Polish Maritime Research FeedSciendo RSS Feed for Polish Maritime Research Maritime Research 's Cover Study of Effect of Trim on Performance of 12500DWT Cargo Ship Using Ranse Method<abstract> <title style='display:none'>Abstract</title> <p>This paper deals with the results of studying the effect of trim on the performance of series cargo ship 12500DWT in full scale at two operating conditions by using the RANSE method. The Body Force Propeller method is used to simulate a rotating propeller behind the ship. The numerical predicted results at the ballast condition were verified and validated with sea trial data. The ship’s engine power curves for different trim conditions at two operating conditions were carried out to produce a data source to evaluate the effect of trim on the performance of the 12500DWT cargo ship. The results indicate that if the ship operates under optimum trim conditions, this can decrease the ship’s engine power in a range from 2.5 to 4.5% depending on different loading conditions and ship speeds. Finally, the paper also provides detailed differences in flow around the ship due to trim variation to explain the physical phenomenon of changing ship performance.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Heave Plates with Holes for Floating Offshore Wind Turbines<abstract> <title style='display:none'>Abstract</title> <p>The paper presents an innovative solution which is heave plates with holes. The long-known heave plates are designed to damp the heave motion of platforms. They are most often used for Spar platforms. The growing interest in this type of platform as supporting structures for offshore wind turbines makes it necessary to look for new solutions. Based on the available literature and the authors’ own research, it was concluded that the main element responsible for the damping of heave plates is not so much the surface of the plate, but its edge. Therefore, it was decided to investigate the effect of the holes in heave plates on their damping coefficient. Model tests and CFD calculations were performed for three different structures: a smooth cylinder, a cylinder with heave plates with a diameter of 1.4 times the diameter of the cylinder, and a cylinder with the same plate, in which 24 holes were cut (Fig. 1). Free Decay Tests (FDT) were used to determine the damping coefficient and the natural period of heave, and then the values obtained were compared. The full and punched heave-plate designs were also tested with regular waves of different periods to obtain amplitude characteristics. The results obtained are not unequivocal, as a complex motion appears here; however, it is possible to clearly define the area in which the damping of a plate with holes is greater than that of a full plate.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Prediction of Weld Deformations by Numerical Methods - Review<abstract> <title style='display:none'>Abstract</title> <p>The welding process is the basic technique of joining in the shipbuilding industry. This method generates welding distortions that cause a lot of problems during the manufacturing process due to both the time and cost of straightening as well as their influence on later stages of production. Proper preparation of welding processes plays a growing role in the shipbuilding industry and the development of calculating tools is being observed. The paper presents a review and critical analysis of numerical methods for the assessment of welding distortion.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Research on Optimal Design of Spudcan Structures to Ease Spudcan-Footprint Interactions in Clay and Comparative Analyses with Different Measures<abstract> <title style='display:none'>Abstract</title> <p>In order to ease consequences of spudcan-footprint interactions during jack-up rigs reinstalling in the vicinity of an existing seabed footprint, three new types of spudcan shapes, that is, a lotus-shaped spudcan with six circular holes, a flat-bottomed spudcan, and a concave-shaped spudcan, were proposed to perform an optimizing study of the spudcan structures, and the effectiveness of them were analyzed comparatively with other different measures. Firstly, 3D Large Deformation Finite Element (LDFE) analyses were carried out using the Coupled Eulerian-Lagrangian (CEL) method in the commercial finite element package ABAQUS. After calibrating the validity of the numerical calculation model against existing centrifuge test data and LDFE results, the differences in interaction mechanism between the novel spudcans and the generic spindle-shaped spudcan were studied when penetrating near an existing footprint with an eccentric distance of 0.5D, and the horizontal range of plastic deformation of the disturbed soils, the inclination angle of the spudcan and the offset distance of the pile legs were analyzed comparatively as well. The results show that the proposed novel spudcans can mitigate the maximum horizontal sliding force and the maximum bending moment at the top of the pile leg obviously, compared with those of the generic one, which were reduced by 32.59%, 22.47%, 28.18%, and 26.32%, 12.88%, 18.02%, respectively. It also can be seen that all novel structures can ease the adverse consequences of spudcan-footprint interactions effectively, and can improve the in -place stability of the spudcan as well. Finally, three possible measures in mitigating interactions of the spudcan-footprint were contrasted, that is, the novel spudcan (represented by the lotus-shaped spudcan with six holes), stomping method, and perforation drilling method. The results show that all of them can reduce adverse impacts induced by interactions of the spudcan-footprint, and also can improve the in-place stability of the spudcan during reinstallation. In addition, among them, according to the effect of reducing the additional stress of the spudcan, the effectiveness of them can be listed as follows: perforation drilling near an existing footprint &gt; the lotus-shaped spudcan with six holes &gt; stomping method. In terms of the vertical bearing capacity of the spudcan, the lotus-shaped spudcan with six holes can improve it as much as 16.33% compared with the spindle-shaped structure due to the particularity of the structure. While reducing the continuity and strength of soil foundations, the perforation drilling measure leads to the decrease of the vertical bearing capacity of the spudcan by 13.07%. It can be concluded that all the three measures have merits and demerits, so the relevant construction environment conditions and engineering practice should be fully considered when selecting measures to deal with interactions of the spudcan-footprint.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Research on Preventive Maintenance Strategies and Systems for in-Service Ship Equipment<abstract> <title style='display:none'>Abstract</title> <p>With continuous improvements in the function and performance of ship equipment, mechanisms of failure have become more and more complicated. To avoid over-maintenance or under-maintenance in existing routine ship maintenance strategies, a ship-level method for repair decisions based on the preventive maintenance concept is proposed in this paper. First, the anticipated repair demand levels of key components are calculated using an improved failure mode and effects analysis (FMEA) method; second, a Weibull distribution model is established, and the parameters are estimated using the maximum likelihood estimation (MLE) to predict the characteristic life of the equipment; then, logical decision principles and rule-based reasoning (RBR) are used to determine the ship repair level and repair timing. Finally, the feasibility and application value of the proposed repair strategy were verified by case studies, and a ship-level system for repair decisions was established.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Automated Motion Heatmap Generation for Bridge Navigation Watch Monitoring System<abstract> <title style='display:none'>Abstract</title> <p>Most ship collisions and grounding accidents are due to errors made by watchkeeping personnel (WP) on the bridge. International Maritime Organization (IMO) adopts the resolution on the Bridge Navigation Watch Alarm System (BNWAS) detecting operator disability to avert these accidents. The defined system in the resolution is very basic and vulnerable to abuse. There is a need for a more advanced system of monitoring the behaviour of WP to mitigate watchkeeping errors. In this research, a Bridge Navigation Watch Monitoring System (BNWMS) is suggested to achieve this task. Architecture is proposed to train a model for BNWMS. The literature reveals that vision-based sensors can produce relevant input data required for model training. 2D body poses belonging to the same person are estimated from multiple camera views by using a deep learning-based pose estimation algorithm. Estimated 2D poses are projected into 3D space with a maximum 8 mm error by utilising multiple view computer vision techniques. Finally, the obtained 3D poses are plotted on a bird’s-eye view bridge plan to calculate a heatmap of body motions capturing temporal, as well as spatial, information. The results show that motion heatmaps present significant information about the behaviour of WP within a defined time interval. This automated motion heatmap generation is a novel approach that provides input data for the suggested BNWMS.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00On the Use of Selected 4th Generation Nuclear Reactors in Marine Power Plants<abstract> <title style='display:none'>Abstract</title> <p>This article provides a review of the possibility of using different types of reactors to power ships. The analyses were carried out for three different large vessels: a container ship, a liquid gas carrier and a bulk carrier. A novelty of this work is the analysis of the proposal to adapt marine power plants to ecological requirements in shipping by replacing the conventional propulsion system based on internal combustion engines with nuclear propulsion. The subjects of comparison are primarily the dimensions of the most important devices of the nuclear power plant and the preliminary fitness analysis. It was assumed for this purpose that the nuclear power plant fits in the engine room compartment and uses the space left after the removal of the combustion engines. At the same time, this propulsion provides at all times sufficient energy for port, technological and shipping operations at an economically justifiable speed. For deep-sea vessels, which are supposed to reach null emissions of CO, CO2, NOx, SOx and H2O, this is one of the most reasonable solutions. Finally the paper proves that all the above-mentioned marine functions could be effectively applied in power plants equipped with 4th generation nuclear reactors.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Dynamic Motions of the Cabin Mounted on the Mono-Hull Planing Boat Using Suspension System in Waves<abstract> <title style='display:none'>Abstract</title> <p>The necessity for higher speed and appropriate seakeeping performance of boats has led to extensive research. Hence, this research mainly discusses the optimal behavior of the boat against motions. From an economic point of view, reducing motions of the boat minimizes the damage caused by shock and vibration to the boat and equipment. Other benefits include comfort and safety and, as a result, improved human operating ability. Suspension systems are rarely used as motion controller in a boat. In multi-hull boats, the hull is an inseparable part of the vessels, so the wave will affect crew and equipment. This paper proposes and evaluates a novel concept boat equipped with a suspended cabin. The hull and superstructure (cabin) are separated in this new form by a simple passive suspension system. This study used numerical analysis to examine the seakeeping performance of the planing boat Fridsma model equipped with a passive suspension system under regular wave conditions. The hydrodynamics of the planing hull were modeled using commercial software, STAR-CCM+. For simulation of the passive suspension system between boat and cabin, MATLAB software was used. Results showed that the motion of the cabin, which is where the crew and equipment are located, decreased in regular waves.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00An Acoustic Sea Glider for Deep-Sea Noise Profiling Using an Acoustic Vector Sensor<abstract> <title style='display:none'>Abstract</title> <p>An acoustic sea glider has been developed for ambient sea noise measurement and target detection through the deployment of an acoustic vector sensor (AVS). The glider was designed with three cabins connected in sequence and it can dive to depths exceeding 1200m. The AVS fixed on the glider measure acoustic pressure and particle velocities related to undersea noise, and the inner attitude sensors can effectively eliminate the estimation deviation of the direction of arrival. The inherent self-noises of the acoustic sea glider and AVS are presented respectively in respect to the Knudsen spectra of sea noise. Sea trial results indicate that the AVS could work well for undersea noise measurement when the glider is smooth sliding, and the target azimuth estimated by AVS after correction is remarkably consistent with the values measured by the GPS, and direction-finding errors are less than 10 degrees. The research in this paper shows that the acoustic sea glider is able to undertake tasks such as a wide range of underwater acoustic measurement and detection.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Study on Dynamic Response of Offshore Wind Turbine Structure Under Typhoon<abstract> <title style='display:none'>Abstract</title> <p>Floating offshore wind turbines are easily affected by typhoons in the deep sea, which may cause serious damage to their structure. Therefore, it is necessary to study further the dynamic response of wind turbine structures under typhoons. This paper took the 5MW floating offshore wind turbine developed by the National Renewable Energy Laboratory (NREL) as the research object. Based on the motion theory of platforms in waves, a physical model with a scale ratio of 1:120 was established, and a hydraulic cradle was used to simulate the effect of waves on the turbines. The dynamic response characteristics of offshore wind turbines under typhoons are systematically studied. The research results clarified that the turbine structure is mainly affected by wave loads under typhoons, and its motion response reaches its maximum value under the action of extreme wave loads. The research results of this paper can provide reference value for the design of offshore wind turbine structures under typhoons.</p> </abstract>ARTICLE2022-04-26T00:00:00.000+00:00Application of Computer Identification and Location Algorithm in Small far Infrared Target Recognition of Ship Under Surge Interference<abstract><title style='display:none'>Abstract</title><p> The small far infrared target of ship in surge interference is easy to have visual deviation causing the low accuracy of target positioning and the bad target identification performance. In order to improve the accuracy of far small infrared targets recognition of ship under surge interference, this paper proposed far small infrared target recognition algorithm of ship based on distributed target position estimation and DOA location in computer vision model for constructing coherent distributed source array model of far small infrared target distribution of ship. This algorithm used MUSIC algorithm for the beamforming processing of far small infrared target echo model of ship. Combined with the adaptive filtering algorithm we carried out the surge interference suppression and the estimation of central direction of arrival and angle spread of far small infrared target of ship through multidimensional spectrum peak searching algorithm, realizing the joint estimation of distance of ship target, DOA and frequency parameters, so as to realize the accurate positioning and recognition of targets. Simulation results show that using this method for the far small infrared target recognition of ship under surge interference, the spectral peak sharpness of spectral peak search of target position is high, side-lobe suppression performance is good, which shows the high accuracy of target position estimation and location, the accuracy and anti-interference performance of far small infrared target recognition of ship is good, and has superior performance.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00Multi-Auv Distributed Task Allocation Based on the Differential Evolution Quantum Bee Colony Optimization Algorithm<abstract><title style='display:none'>Abstract</title><p> The multi-autonomous underwater vehicle (AUV) distributed task allocation model of a contract net, which introduces an equilibrium coefficient, has been established to solve the multi-AUV distributed task allocation problem. A differential evolution quantum artificial bee colony (DEQABC) optimization algorithm is proposed to solve the multi-AUV optimal task allocation scheme. The algorithm is based on the quantum artificial bee colony algorithm, and it takes advantage of the characteristics of the differential evolution algorithm. This algorithm can remember the individual optimal solution in the population evolution and internal information sharing in groups and obtain the optimal solution through competition and cooperation among individuals in a population. Finally, a simulation experiment was performed to evaluate the distributed task allocation performance of the differential evolution quantum bee colony optimization algorithm. The simulation results demonstrate that the DEQABC algorithm converges faster than the QABC and ABC algorithms in terms of both iterations and running time. The DEQABC algorithm can effectively improve AUV distributed multi-tasking performance.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00Marine Search and Rescue of UAV in Long-Distance Security Modeling Simulation<abstract><title style='display:none'>Abstract</title><p> Long-distance safety of Marine search and rescue using drones can improve the searching speed. The current method is based on the long distance security classification of UAV.The degree of accuracy is low. A long-distance security modeling approach based on ArduinoMiniPro’s Marine search-and-rescue applying UAV is proposed. The method puts the fault tree analysis and relevant calculation for risk identification into use. The main factors affecting the safety of unmanned aerial vehicle (UAV) are long-distance searching and rescuing. The experimental results show that the proposed method can effectively build modeling for the long-distance safety of the Marine search and rescue UAV</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00A Conceptual Model of Excellent Performance Mode of Port Enterprise Logistics Management<abstract><title style='display:none'>Abstract</title><p> Port as one of the key hubs of international logistics, which has become the main part and the base of global logistics management. The port enterprises, plays an important role in the global supply chain. However, due to the lack of understanding in port supply chain management, coordination between the port enterprises, the integration of business process is not perfect, the lack of information sharing between various organizations, ports enterprises usually failed to fully play its positive role. Based on this, the paper makes the port enterprises as the research object, and introduces the excellent performance mode into the port enterprises. In order to study the port enterprises how to carry out effective quality management, and formation the coordination and integration of upstream and downstream of enterprises, so as to realize the competitive advantage in port logistics.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00A Positioning Lockholes of Container Corner Castings Method Based on Image Recognition<abstract><title style='display:none'>Abstract</title><p> This article proposes a method of locating and recognizing lockholes in shipping container corner castings. This method converts the original image of the containers captured by a camera into the HSV (Hue, Saturation, Value) color space. To reduce the influence of the surface color of the containers and lights from the environment on the locating and recognizing algorithm, most noisy points of the image are filtered by binarization and a morphology opening operation to make the features of the containers clearer in the image. Thus, the container body can be separated from the total image. Then, the position and size of the corner castings are defined through calculation based on the international standard of the shipping container size. Lastly, by using this method, we can locate the corner casting in the image by using the General Hough Transform fitting algorithm onto ellipses.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00Nonlinear PTO Effect on Performance of Vertical Axisymmetric Wave Energy Converter Using Semi-Analytical Method<abstract><title style='display:none'>Abstract</title><p> The wave energy, as a clean and non-pollution renewable energy sources, has become a hot research topic at home and abroad and is likely to become a new industry in the future. In this article, to effectively extract and maximize the energy from ocean waves, a vertical axisymmetric wave energy converter (WEC) was presented according to investigating of the advantages and disadvantages of the current WEC. The linear and quadratic equations in frequency-domain for the reactive controlled single-point converter property under regular waves condition are proposed for an efficient power take-off (PTO). A method of damping coefficients, theoretical added mass and exciting force are calculated with the analytical method which is in use of the series expansion of eigen functions. The loads of optimal reactive and resistive, the amplitudes of corresponding oscillation, and the width ratios of energy capture are determined approximately and discussed in numerical results.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00An Application of 24Model to Analyse Capsizing of the Eastern Star Ferry<abstract><title style='display:none'>Abstract</title><p> In the present study, the Eastern Star ferry accident was analyzed via 24Model. 24Model, as an accident causation model based on system thinking, holds that all causations of the accident are hazards and all hazards in the system need to be identified and comprehensively controlled in accident prevention. The result showed that five factors were the main causes of the accident. First, the direct causes: bad weather, the bad condition of the hull and the unsafe acts of the captain. Second, the indirect cause: the lack of safety awareness and safety knowledge of both the captain and the company’s senior management. Third, there were loopholes in safety management system, including the training, supervision and execution of the company. Forth, the root cause: the company didn’t establish a good safety culture. Last, the external causes: the severe market pressure, excessive regulatory authorities with puzzled relations and responsibilities-seriously hindered effective supervision. In order to prevent this kind of accident and to secure shipping system, the shipping companies and the relevant regulatory units should draw lessons from the five factors mentioned above, and take measures to identify and control those hazards.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00Experimental and Optimization Design of Offshore Drilling Seal<abstract><title style='display:none'>Abstract</title><p> Three-cone bit is the key equipment in the exploration of the oil in offshore drilling and exploration, the bearing system and the seal system are the critical components for the bit. Especially in the offshore drilling environment, the seal design need to be carefully considered. A multi-objective optimization design including orthogonal design method and F-test with finite element analysis for a three-cone bit seal is proposed. Firstly, the calculation method of optimization targets are given, including the minimization of maximum contact pressure and leakage rate analyzed by ANSYS and MATLAB respectively, to maximize seal life and reliability. Then, an orthogonal experiment approach is used to investigate the effects of the eleven parameters on the seal performance, and the influence degrees of the seal factors on the optimization targets have been confirmed by F-test, and the reasonable factors can be determined by the trend of the targets. Finally, in order to validate the analysis results, a new seal was designed and tested on a seal tester compared to the previous seal. In this test, the seal maximum interface temperature that reflects the position of maximum contact pressure can be obtained by using three high precision thermocouples. Both the experiment results and the numerical analyses proved that the maximum contact pressure and leakage rate of the improved seal have been reduced compared to the previous.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00Evolution of Hierarchical Structure and Spatial Pattern of Coastal Cities in China – Based on the Data of Distribution of Marine-Related Enterprises<abstract><title style='display:none'>Abstract</title><p> In this paper, a comprehensive research of the evolution of the hierarchical structure and spatial pattern of coastal cities in China was conducted based on the data of distribution of the headquarters and subsidiaries of marine-related enterprises in 1995, 2005 and 2015 using the city network research method proposed by Taylor. The results of the empirical research showed: China’s coastal city network had an obvious hierarchical characteristics of “national coastal cityregional coastal city-sub-regional coastal city-local coastal city”, in the 20 years of development process, the hierarchies of coastal cities in China showed a hierarchical progressive evolution; in past 20 years, the spatial pattern and network structure of coastal cities in China tended to be complete, and the city network was more uniform, forming a “three tiers and three urban agglomerations” network structure; the strength of connection among the cities was obviously strengthened, and the efficiency of urban spatial connection was improved overall.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00Risk of the Maritime Supply Chain System Based on Interpretative Structural Model<abstract><title style='display:none'>Abstract</title><p> Marine transportation is the most important transport mode of in the international trade, but the maritime supply chain is facing with many risks. At present, most of the researches on the risk of the maritime supply chain focus on the risk identification and risk management, and barely carry on the quantitative analysis of the logical structure of each influencing factor. This paper uses the interpretative structure model to analysis the maritime supply chain risk system. On the basis of comprehensive literature analysis and expert opinion, this paper puts forward 16 factors of maritime supply chain risk system. Using the interpretative structure model to construct maritime supply chain risk system, and then optimize the model. The model analyzes the structure of the maritime supply chain risk system and its forming process, and provides a scientific basis for the controlling the maritime supply chain risk, and puts forward some corresponding suggestions for the prevention and control the maritime supply chain risk.</p></abstract>ARTICLE2017-11-22T00:00:00.000+00:00en-us-1