Journal articles on the topic 'Ship and Platform Structures'
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1
Lu, Yun, Jinbo Wu, Weijia Li, and Yaozhong Wu. "A New Six-DoF Parallel Mechanism for Captive Model Test." Polish Maritime Research 27, no. 3 (September 1, 2020): 4–15. http://dx.doi.org/10.2478/pomr-2020-0041.
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AbstractIn order to obtain the hydrodynamic coefficients that can save cost and meet the accuracy requirements, a new hydrodynamic test platform based on a 6DoF (six degrees of freedom) parallel mechanism is proposed in this paper. The test platform can drive the ship to move in six degrees of freedom. By using this experimental platform, the corresponding hydrodynamic coefficients can be measured. Firstly, the structure of the new device is introduced. The working principle of the model is deduced based on the mathematical model. Then the hydrodynamic coefficients of a test ship model of a KELC tank ship with a scale of 1:150 are measured and 8 typical hydrodynamic coefficients are obtained. Finally, the measured data are compared with the value of a real ship. The deviation is less than 10% which meets the technical requirements of the practical project. The efficiency of measuring the hydrodynamic coefficients of physical models of ships and offshore structures is improved by the device. The method of measuring the hydrodynamic coefficients by using the proposed platform provides a certain reference for predicting the hydrodynamic performance of ships and offshore structures.
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Liu, Ming. "Research on Motion Analysis and Simulation Technology of Double Ship Floating Installation of Large Structures." Journal of Physics: Conference Series 2417, no. 1 (December 1, 2022): 012006. http://dx.doi.org/10.1088/1742-6596/2417/1/012006.
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The offshore platform is developing towards the trend of large-scale, complex and centralized. Compared with the single-ship floating installation, the double-ship floating installation can be applied to the installation of more complex and diversified offshore platforms and can improve the safety of installation. It is the development direction of large-scale offshore platform installation technology. In this paper, the motion analysis and simulation technology of double ship floating installation are deeply studied. Through momentum analysis, load model, and motion model establishment, the kinematics simulation is carried out under the South China Sea working condition, which provides basic kinematics data for double ship floating installation.
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Goldan, Michael, and Robert J. G. A. Kroon. "As-Built Product Modeling and Reverse Engineering in Shipbuilding Through Combined Digital Photogrammetry and CAD/CAM Technology." Journal of Ship Production 19, no. 02 (May 1, 2003): 98–104. http://dx.doi.org/10.5957/jsp.2003.19.2.98.
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Ship repair, as a technological "lesser brother" of shipbuilding, still contains major elements of manual labor. In the past years, ship repair and the conversion of ships and offshore structures came to rely increasingly on modern computer-aided design and manufacturing (CAD and CAM) information systems for speedy generation of the required engineering information. An often-encountered problem is the lack of product information in electronic form or in any other form. Such information is needed for engineering of new parts for damaged or converted ships and platforms. In such cases one needs to build the virtual product model from the existing as-built object up to an engineering-detail level; hence, the terms "as-built modeling" and "reverse engineering." The paper presents the results of a multiyear project with the code name AMORES, which focuses on improving lead time and economic efficiency in ship and offshore platform repair and conversion in the Netherlands. Existing and newly developed photogrammetric measuring techniques were used to generate as-built models of double curved three-dimensional surfaces of ships and platforms. These were fed into standard CAD/CAM systems to engineer and manufacture new ship hull or platform parts to replace damaged areas. The main advantages of the new method are savings in lead time (measurements, engineering) and the replacing of costly manual labor by modern digital photogrammetry. The paper will focus on the new developments, the experienced difficulties, and the advantages of this new technique in ship repair.
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Zhang, Jing, Qi Wang, and Fenzhen Su. "Automatic Extraction of Offshore Platforms in Single SAR Images Based on a Dual-Step-Modified Model." Sensors 19, no. 2 (January 9, 2019): 231. http://dx.doi.org/10.3390/s19020231.
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The quantity and location of offshore platforms are of great significance for marine oil spill monitoring and offshore oil-gas development. In the past, multiphase medium- and low-resolution optical or radar images have been used to remove the interference of ship targets based on the static position of a platform to extract the offshore platform, resulting in large demands and high image data costs. According to the difference in shape between offshore platforms (not elongated) and ships (elongated shapes) in SAR (synthetic aperture radar) images, this paper proposes an automatic extraction method for offshore platforms in single SAR images based on a dual-step-modified model. First, the two-parameter CFAR (constant false alarm rate) algorithm was used to detect the possible offshore platform targets; then, the Hough transform was introduced to detect and eliminate ship targets with linear structures. Finally, the final offshore platform was obtained. Experiments were carried out in four study areas in the Beibu Gulf basin and the Pearl River estuary basin in the northern South China Sea. The results show that the method has a good extraction effect in the above research area, and the extraction accuracy rate of offshore platforms is 86.75%. A single SAR image can obtain satisfactory extraction results, which greatly saves on image data cost.
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Lim, Jae-Jun, Dae-Won Kim, Woon-Hee Hong, Min Kim, Dong-Hoon Lee, Sun-Young Kim, and Jae-Hoon Jeong. "Application of Convolutional Neural Network (CNN) to Recognize Ship Structures." Sensors 22, no. 10 (May 18, 2022): 3824. http://dx.doi.org/10.3390/s22103824.
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The purpose of this paper is to study the recognition of ships and their structures to improve the safety of drone operations engaged in shore-to-ship drone delivery service. This study has developed a system that can distinguish between ships and their structures by using a convolutional neural network (CNN). First, the dataset of the Marine Traffic Management Net is described and CNN’s object sensing based on the Detectron2 platform is discussed. There will also be a description of the experiment and performance. In addition, this study has been conducted based on actual drone delivery operations—the first air delivery service by drones in Korea.
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Dong, G. H., L. Sun, Z. Zong, H. W. An, and Y. X. Wang. "Numerical Analysis of Ship-Generated Waves Action on a Vertical Cylinder." Journal of Ship Research 53, no. 02 (June 1, 2009): 93–105. http://dx.doi.org/10.5957/jsr.2009.53.2.93.
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In this paper, the action of ship-generated waves on a nearby vertical cylinder is considered in pure theory. Intensive demands of modern sea transportation result in larger and larger ships. These ships generate high waves as they move in calm water. The ship-generated waves can travel long distances without much attenuation. They are so strong that they might cause damage to nearby marine structures (e.g., platforms, river banks, breakwaters, etc.). Therefore, it is necessary to evaluate the forces of ship-generated waves acting on nearby marine structures. The problem turns out to be composed of two problems: evaluation of waves generated by a moving ship (ship-wave problem) and evaluation of the action of ship waves on a cylinder (wave-action problem). Here the wave-action problem is computed in detail with a boundary element method in time domain. And the ship-wave problem is evaluated in the well-known Michell thin-ship theory. Thus, the problem posed in this paper is finally solved using numerical methods by combining the ship-wave and wave-action problems. The numerical analyses of the result are: The resultant forces and moments acting on the cylinder are surprisingly large, characterized by being highly oscillatory. The periods of the oscillations are proportional to ship speed. The actions of ship-generated waves on nearby structures are not negligible. This is a new factor necessary to be considered for design of both marine structures and ships. Meanwhile, the potential fatigue damage resulting from oscillations of the forces and moments should be considered, too.
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Lin, Hong, Chang Han, Lei Yang, Hassan Karampour, Haochen Luan, Pingping Han, Hao Xu, and Shuo Zhang. "Dynamic Performance and Crashworthiness Assessment of Honeycomb Reinforced Tubular Pipe in the Jacket Platform under Ship Collision." Journal of Marine Science and Engineering 10, no. 9 (August 26, 2022): 1194. http://dx.doi.org/10.3390/jmse10091194.
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The collision between the pipe legs of jacket platforms and bypassing ships is of great concern for the safety assessment of platforms. Honeycomb structures have been widely used owing to their unique deformation and mechanical properties under dynamic impact loads. In this paper, two typical honeycomb structures, namely hexagonal honeycomb and arrow honeycomb, were constructed for the impact protection of inclined pipe legs in jacket platforms, and the present study aimed to assess the dynamical performance and crushing resistance of the designed honeycomb reinforced structure under ship collision by using the numerical simulation software ANSYS/LS-DYNA. The dynamical performance of the honeycomb reinforced pipe leg was investigated considering various influential parameters, including the impact velocity and impact direction. The crashworthiness of the two types of honeycomb was evaluated and compared by different criteria, namely the maximum impact depth (δmax), specific energy absorption (SEA) and the proposed index offset sliding (OS). The results demonstrated that both the hexagonal honeycomb structure and the arrow honeycomb structure can reduce the damage of inclined pipe legs caused by ship collision, while the hexagonal honeycomb can provide the better anti-collision capacity, which can well reduce the offset sliding and better protect the pipe leg from ship collision.
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Wu, Gongxing, Xiaolong Zhao, Yushan Sun, and Linling Wang. "Cooperative Maneuvering Mathematical Modeling for Multi-Tugs Towing a Ship in the Port Environment." Journal of Marine Science and Engineering 9, no. 4 (April 4, 2021): 384. http://dx.doi.org/10.3390/jmse9040384.
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The towing operation of multi-tug-assisted ship navigation mainly relies on the experience of the captain, and there is no set of effective operation methods. Therefore, it is difficult to achieve accurate assisted navigation when multiple tugboats work in coordination. The calculation method of maneuverability of the towing system with multi-tug-assisted navigation is proposed in this paper. In view of the complexity of multi-tug-assisted large ship maneuvering, this article focuses on solving the problems of force analysis and maneuvering modeling between the multi-tug and ship systems. Firstly, a maneuvering mathematic model for towing ships is established, and the hydrodynamic force of the hull, rope force of the tugs, and force of wind interference are analyzed. The thrust and moment of the ducted azimuthal propeller are calculated, and the mathematical model of the tug’s cable tension is discussed. Then, the fourth-order Runge–Kutta method is used to solve the differential equations of the maneuvering motion of the ships and each tug. Based on the ship-towing process by multiple tugs, a multi-tug-assisted ship towing simulation platform was built by using the Visual Studio development tool. Finally, on the simulation platform, multi-tug longitudinal-towing-simulation experiments at different speeds were carried out, and the simulation of turning towing maneuvers under the influence of wind was done. The simulation results showed that as the towing speed increases, the initial towing speed fluctuates greatly. There is a significant drift effect on the ships by the wind force. And the wind will cause a fluctuation in the tug’s rope force. The simulation of the multi-tugs towing a ship entering the port was carried out in the port environment. The results showed that the multi-tug towing system and simulation platform may be used for the safety training of the tug’s crew.
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Grewal, Gage S., and Marcus M. K. Lee. "Strength of Minimum Structure Platforms Under Ship Impact." Journal of Offshore Mechanics and Arctic Engineering 126, no. 4 (November 1, 2004): 368–75. http://dx.doi.org/10.1115/1.1839883.
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This paper presents the findings of a numerical investigation into the strength of minimum structure platforms subject to a ship impact. The study has identified important design issues that should be addressed in order to improve the survivability and continued serviceability of minimum structures after a ship impact. It was found that, due to a lack of research effort, design guidelines governing ship impact on minimum structures are lacking in comparison with conventional jacket platforms. In particular, requirements governing the minimum amount of plastic energy absorption in minimum structures are not clearly defined. Ship impact analyses were therefore carried out in order to compare their structural integrity with that for a jacket under ship collision conditions and to evaluate the effects on their ultimate strength. The study not only established any degradation of system strength, but has also determined the amount of plastic energy absorption under various impact scenarios.
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Jones, J., and R. Fraser. "Ship impact on concrete offshore platform legs." Proceedings of the Institution of Civil Engineers - Structures and Buildings 162, no. 1 (February 2009): 21–25. http://dx.doi.org/10.1680/stbu.2009.162.1.21.
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Li, Yan, Yaolong Li, Zhimin Zhao, Yougang Tang, Haoran Li, Yijian Zhang, and Yinan Hu. "Dynamic Responses of the Cylindrical Floating Drilling Production Storage and Offloading System with Annular Anti-Motion Structures under the Survival Sea Scenario." Journal of Marine Science and Engineering 11, no. 1 (January 14, 2023): 218. http://dx.doi.org/10.3390/jmse11010218.
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At present, dry wellheads are usually adopted on small-storage TLP and SPAR platforms to develop offshore oil and gas because of the robust hydrodynamic performance under severe-wind seas. On the other hand, FPSO and FDPSO platforms that have a larger storage capacity can hardly use this cost-saving facility due to their relatively poor vertical motion performance. Cylindrical FPSOs are proposed to improve the heave performance of ship-type FPSOs, but their behaviors are still too large to adopt the dry wellheads. In the present work, a cylindrical FDPSO platform is proposed based on the FWPSO platform, adding an extension cylinder and a new damping structure at the bottom. Their hydrodynamic performances are calculated by the potential theory and compared in the frequency domain. Taking two particular mooring systems, including both catenary and ‘chain-polyester-chain’ types, and the survival sea scenario in the South China Sea into account, a time-domain coupling analysis was adopted to simulate the dynamic performance of the platform-mooring system. The feasibility of dry wellhead adoption on the FDPSO is discussed by investigating the platform motion and the mooring tension. The results show that the FCDS platform with the ‘chain-polyester-chain’-type mooring system can meet the motion response requirements, and the mooring system can also meet the requirements of the specification.
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Mo, Zonglai, Kefeng Xie, Fengcheng Zhao, Jun Li, and Yanjun Li. "A Small Floating Platform Designed for Unmanned Defense System." Journal of Marine Science and Engineering 11, no. 2 (January 26, 2023): 278. http://dx.doi.org/10.3390/jmse11020278.
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A small floating platform designed for an unmanned short-range defense system is proposed. The structures of the proposed floating platform and weapon system are detailed and described. The floating platform is investigated via virtual prototype technology in the aspects of the platform motion under sea waves of up to Beaufort wind and Douglas sea (wind-sea) scale 5. The motion equations of the floating platform are established according to the ship motion theory, and the movement of the floating platform under different wind-sea scales are simulated and analysed via multi-body fluid dynamics analysis software. To decide the proper size of the platform, the dynamic response of the floating platforms with different sizes is analysed and evaluated under various sea conditions based on multi-body dynamics. A scaled model experiment was conducted and compared with simulation results to verify the theoretical model. A verification experiment was also conducted in a water tank for the performance of the platform via simulated wave disturbance. Results show that the designed floating platform could provide a stable platform in the horizontal direction under a wind-sea scale 3 environment for the defense weapon system, which well meets the design requirement.
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Liu, Wei-Qin, Luo-Nan Xiong, Guo-Wei Zhang, Meng Yang, Wei-Guo Wu, and Xue-Min Song. "Research on Hydroelastic Response of an FMRC Hexagon Enclosed Platform." Symmetry 13, no. 7 (June 22, 2021): 1110. http://dx.doi.org/10.3390/sym13071110.
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The numerical hydroelastic method is used to study the structural response of a hexagon enclosed platform (HEP) of flexible module rigid connector (FMRC) structure that can provide life accommodation, ship berthing and marine supply for ships sailing in the deep ocean. Six trapezoidal floating structures constitute the HEP structure so that it is a symmetrical very large floating structure (VLFS). The HEP has the characteristics of large area and small depth, so its hydroelastic response is significant. Therefore, this paper studies the structural responses of a hexagon enclosed platform of FMRC structure in waves by means of a 3D potential-flow hydroelastic method based on modal superposition. Numerical models, including the hydrodynamic model, wet surface model and finite element method (FEM) model, are established, a rigid connection is simulated by many-point-contraction (MPC) and the number of wave cases is determined. The load and structural response of HEP are obtained and analyzed in all wave cases, and frequency-domain hydroelastic calculation and time-domain hydroelastic calculation are carried out. After obtaining a number of response amplitude operators (RAOs) for stress and time-domain stress histories, the mechanism of the HEP structure is compared and analyzed. This study is used to guide engineering design for enclosed-type ocean platforms.
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Ren, Zhen, Jianhua Wang, and Decheng Wan. "Investigation of the Flow Field of a Ship in Planar Motion Mechanism Tests by the Vortex Identification Method." Journal of Marine Science and Engineering 8, no. 9 (August 24, 2020): 649. http://dx.doi.org/10.3390/jmse8090649.
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Planar motion mechanism (PMM) tests provide a means of obtaining the hydrodynamic derivatives needed to assess ship maneuverability properties. In this paper, the self-developed computational fluid dynamic (CFD) solver based on the open source code platform OpenFOAM, naoe-FOAM-SJTU, associated with the overset grid method is used to simulate the complex viscous flow field of PMM tests for a benchmark model Yupeng Ship. This paper discusses the effect of several parameters such as the drift angle and period on the hydrodynamic performance of the ship and compares the time histories of the predicted forces and moments with experimental data. To investigate the complex viscous flows with a large separation, four vortex identification methods are used to capture the vortex structures. The results show that the forces and moments are in good agreement in static drift and dynamic tests. By comparing the vortex structures, it is found that the third generation vortex identification methods, OmegaR and Liutex, are able to more accurately capture the vortex structures. The paper concludes that the present numerical scheme is reliable and the third generation vortex identification methods are more suitable for displaying the vortex structures in a complex viscous flow field.
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Xiao, Yuan, Zhi Yao, and Xu Zhang. "Comprehensive Penetration Evaluation Method in Collisions between a Supply Ship and a Semi-Submersible Platform." Processes 10, no. 6 (June 17, 2022): 1212. http://dx.doi.org/10.3390/pr10061212.
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Collisions between ships and offshore platforms frequently occur, with severe consequences. Predicting the collision depth under different conditions is very important to evaluate the severity of the consequences. Considering the time-consuming numerical simulation problem and the accuracy problems of existing approximation algorithms, this paper proposes a comprehensive approach to estimating penetration depths by obtaining two collision coefficients for specific collision structures based on the partial results of numerical simulations and simplified theoretical analysis. In this study, the collision process between a supply ship with a transverse framing stern and an offshore semi-platform was first numerically simulated based on the explicit dynamic method. The changes in ship velocity, impact force, and energy conversion before and after the collision processes were obtained through numerical simulations of the collisions with different speeds and angles. Then, by combining the external dynamics and numerical results, the analytical results of dissipated energy under other collision conditions were obtained using a simulated restitution coefficient. For the following internal dynamics analysis, according to the failure modes of specific structural components in different regions, an appropriate structural energy absorption formula was combined to obtain the relationship between the penetrations and energy absorption in a particular collision area. According to the friction energy ratio derived by the simulation, the penetration depths in the offshore platform were calculated. The results showed that the deviations between the proposed method and direct simulation results were less than 15% in the cases of a medium- to high-energy collision. It can be concluded that the restitution coefficient and friction energy ratio in different collision conditions can be approximately determined for a specific collision system by typical numerical simulations, thus quickly calculating the penetration depths of other conditions.
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Ahmed, Yaseen Adnan, Mohammed Abdul Hannan, Mahmoud Yasser Oraby, and Adi Maimun. "COLREGs Compliant Fuzzy-Based Collision Avoidance System for Multiple Ship Encounters." Journal of Marine Science and Engineering 9, no. 8 (July 22, 2021): 790. http://dx.doi.org/10.3390/jmse9080790.
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As the number of ships for marine transportation increases with the advancement of global trade, encountering multiple ships in marine traffic becomes common. This situation raises the risk of collision of the ships; hence, this paper proposes a novel Fuzzy-logic based intelligent conflict detection and resolution algorithm, where the collision courses and possible avoiding actions are analysed by considering ship motion dynamics and the input and output fuzzy membership functions are derived. As a conflict detection module, the Collision Risk (CR) is measured for each ship by using a scaled nondimensional Distance to the Closest Point of Approach (DCPA) and Time to the Closest Point of Approach (TCPA) as inputs. Afterwards, the decisions for collision avoidance are made based on the calculated CR, encountering angle and relative angle of each ship measured from others. In this regard, the rules for the Fuzzy interface system are defined in accordance with the COLREGs, and the whole system is implemented on the MATLAB Simulink platform. In addition, to deal with the multiple ship encounters, the paper proposes a unique maximum-course and minimum-speed change approach for decision making, which has been found to be efficient to solve Imazu problems, and other complicated multiple-ship encounters.
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Zhang, Zhao, and Junsheng Ren. "Locally Weighted Non-Parametric Modeling of Ship Maneuvering Motion Based on Sparse Gaussian Process." Journal of Marine Science and Engineering 9, no. 6 (June 1, 2021): 606. http://dx.doi.org/10.3390/jmse9060606.
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This paper explores a fast and efficient method for identifying and modeling ship maneuvering motion, and conducts a comprehensive experiment. Through the ship maneuvering test, the dynamics interaction between ship and the environment is obtained. Then, the LWL (Locally Weighted Learning algorithm) underlying architecture is constructed by sparse Gaussian Process to reduce the data requirements of LWL-based ship maneuvering motion modeling and to improve the performance for LWL. On this basis, a non-parametric model of ship maneuvering motion is established based on the locally weighted sparse Gaussian Process, and the traditional mathematical model of ship maneuvering motion is replaced by the generative model. This generative model considers the hydrodynamic effects of ships, and reduces the sensitivity of local weighted learning to sample data. In addition, matrix operations are transferred to the auxiliary platform to optimize the calculation performance of the method. Finally, the simulation results of ship maneuvering motion indicate that this method has the characteristics of efficiency, rapidity and universality, and its accuracy conforms to engineering practice.
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Zhou, Fan, Jing Liu, Hang Zhu, Xiaodong Yang, and Yunli Fan. "A Real-Time Measurement-Modeling System for Ship Air Pollution Emission Factors." Journal of Marine Science and Engineering 10, no. 6 (May 31, 2022): 760. http://dx.doi.org/10.3390/jmse10060760.
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The lack of techniques for monitoring ship emissions all day and in all weather conditions to obtain real-time emission factor values is the main problem in understanding the characteristics of ship emissions, and there is still no perfect solution. In this study, a real-time measurement-modeling system was designed and implemented. The system was divided into three parts: (1) a portable exhaust monitoring device, which could be mounted on a drone, aircraft, patrol boat, dock, and bridge crane, as well as on the shore, to conduct all-weather and real-time online monitoring of ship emissions; (2) a monitoring information platform for ship emissions, based on a Spring + Spring MVC + MyBatis (SSM) framework and Vue front-end technology; and (3) a cloud server that received real-time ship emission measurement data and stored it after verification and analysis to calculate the pollutant gas and particulate matter emission factors. Following development, this system was used to monitor the emissions of ocean-going and inland river ships. Analysis of the acquired data showed that the system could effectively measure the emission factors of ship exhausts full-time in a variety of weather scenarios. This system can improve the efficiency of maritime law enforcement and provide technical support for promoting the construction of ship emission control areas. It can also help researchers obtain ship emission data, as well as an improved understanding of the emission characteristics of ships.
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Palaversa, Marin, Pero Prebeg, and Jerolin Andrić. "Current State of Development of Ship Structural Design and Optimization Methods." Journal of Maritime & Transportation Science 3, no. 3 (June 2020): 171–87. http://dx.doi.org/10.18048/2020.00.13.
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This paper presents state-of-the-art methodologies and methods used in the rationally-based structural design of ships and offshore structures, namely design support system, structural optimization, surrogate modelling and sensitivity analysis. It demonstrates their application in structural design of a platform support vessel. It ends with a list of benefits that a structural designer may expect when the presented methods/methodologies are used. It also shows the obstacles to their full implementation in the engineering practice.
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Zhu, Renchuan, Guoping Miao, and Zhaowei Lin. "Numerical Research on FPSOs With Green Water Occurrence." Journal of Ship Research 53, no. 01 (March 1, 2009): 7–18. http://dx.doi.org/10.5957/jsr.2009.53.1.7.
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Green water loads on sailing ships or floating structures occur when an incoming wave significantly exceeds freeboard and water runs onto the deck. In this paper, numerical programs developed based on the platform of the commercial software Fluent were used to numerically model green water occurrence on floating structures exposed to waves. The phenomena of the fixed floating production, storage, and offloading unit (FPSO) model and oscillating vessels in head waves have been simulated and analyzed. For the oscillating floating body case, a combination idea is presented in which the motions of the FPSO are calculated by the potential theory in advance and computional fluid dynamics (CFD) tools are used to investigate the details of green water. A technique of dynamic mesh is introduced in a numerical wave tank to simulate the green water occurrence on the oscillating vessels in waves. Numerical results agree well with the corresponding experimental results regarding the wave heights on deck and green water impact loads; the two-dimensional fixed FPSO model case conducted by Greco (2001), and the three-dimensional oscillating vessel cases by Buchner (2002), respectively. The research presented here indicates that the present numerical scheme and method can be used to actually simulate the phenomenon of green water on deck, and to predict and analyze the impact forces on floating structures due to green water. This can be of great significance in further guiding ship design and optimization, especially in the strength design of ship bows.
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Silva-Campillo, Arturo, Francisco Pérez-Arribas, and Juan Carlos Suárez-Bermejo. "Health-Monitoring Systems for Marine Structures: A Review." Sensors 23, no. 4 (February 13, 2023): 2099. http://dx.doi.org/10.3390/s23042099.
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This paper presents a comprehensive review of the state-of-the-art developments in health monitoring of marine structures. Monitoring the health of marine structures plays a key role in reducing the risk of structural failure. The authors establish the different sensors with their theoretical foundations and applications in order to determine the optimal position of the sensors on board. Once the data were collected, it was necessary to use for subsequent treatment; thus, the authors identified the different methodologies related to the treatment of data collected by the sensors. The authors provide a historical review of the location of different sensors depending on the type of ship and offshore platform. Finally, this review paper states the conclusions and future trends of this technology.
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Li, Gaocai, Mingzheng Liu, Xinyu Zhang, Chengbo Wang, Kee-hung Lai, and Weihuachao Qian. "Semantic Recognition of Ship Motion Patterns Entering and Leaving Port Based on Topic Model." Journal of Marine Science and Engineering 10, no. 12 (December 16, 2022): 2012. http://dx.doi.org/10.3390/jmse10122012.
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Recognition and understanding of ship motion patterns have excellent application value for ship navigation and maritime supervision, i.e., route planning and maritime risk assessment. This paper proposes a semantic recognition method for ship motion patterns entering and leavingport based on a probabilistic topic model. The method enables the discovery of ship motion patterns from a large amount of trajectory data in an unsupervised manner and makes the results more interpretable. The method includes three modules: trajectory preprocessing, semantic process, and knowledge discovery. Firstly, based on the activity types and characteristics of ships in the harbor waters, we propose a multi-criteria ship motion state recognition and voyage division algorithm (McSMSRVD), and ship trajectory is divided into three sub-trajectories: hoteling, maneuvering, and normal-speed sailing. Secondly, considering the influence of port traffic rules on ship motion, the semantic transformation and enrichment of port traffic rules and ship location, course, and speed are combined to construct the trajectory text document. Ship motion patterns hidden in the trajectory document set are recognized using the Latent Dirichlet allocation (LDA) topic model. Meanwhile, topic coherence and topic correlation metrics are introduced to optimize the number of topics. Thirdly, a visualization platform based on ArcGIS and Electronic Navigational Charts (ENCs) is designed to analyze the knowledge of ship motion patterns. Finally, the Tianjin port in northern China is used as the experimental object, and the results show that the method is able to identify 17 representative inbound and outbound motion patterns from AIS data and discover the ship motion details in each pattern.
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Zhou, Junchi, Ping Jiang, Airu Zou, Xinglin Chen, and Wenwu Hu. "Ship Target Detection Algorithm Based on Improved YOLOv5." Journal of Marine Science and Engineering 9, no. 8 (August 22, 2021): 908. http://dx.doi.org/10.3390/jmse9080908.
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In order to realize the real-time detection of an unmanned fishing speedboat near a ship ahead, a perception platform based on a target visual detection system was established. By controlling the depth and width of the model to analyze and compare training, it was found that the 5S model had a fast detection speed but low accuracy, which was judged to be insufficient for detecting small targets. In this regard, this study improved the YOLOv5s algorithm, in which the initial frame of the target is re-clustered by K-means at the data input end, the receptive field area is expanded at the output end, and the loss function is optimized. The results show that the precision of the improved model’s detection for ship images was 98.0%, and the recall rate was 96.2%. Mean average precision (mAP) reached 98.6%, an increase of 4.4% compared to before the improvements, which shows that the improved model can realize the detection and identification of multiple types of ships, laying the foundation for subsequent path planning and automatic obstacle avoidance of unmanned ships.
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Dopilko, V. O., and K. O. Shchegolska. "The definition of «ship» by international and national regulations." Uzhhorod National University Herald. Series: Law, no. 67 (January 16, 2022): 307–12. http://dx.doi.org/10.24144/2307-3322.2021.67.58.
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The article analyzes the definition of «ship» by international and national regulations. It is noted that there are many examples of the legal definition of «ship». There are attempts in international law to define the term «ship».
The definition of «ship» under the International Convention for the Prevention of Pollution from Ships contains a tautology, as the term «ship» is defined as «ship». Thus, for this Convention, a ship is understood to mean not only ships in the usual sense of the term but also «stationary or floating platforms». In other international legal acts, there is also no unambiguous (universal) interpretation of the concept of «ship». And in one of the most important sources of international maritime law - the comprehensive universal The United Nations Convention on the Law of the Sea 1982, although the term «ship» is often used, there is no norm-definition that should explain it. Based on the study, several features that are inherent in the vessel, namely: the concept of the vessel, is applied only to the Merchant shipping code of Ukraine, and the vessel is understood as a «self-propelled or non-self-propelled floating structure». However, the restriction of the vessel as a «floating structure» from other «floating objects» can be carried out for their intended purpose. Thus, «floating objects», in contrast to ships, are not intended for permanent stay in a floating state but are brought into such a state for their one-time movement or specific work. Therefore, they should not be considered as vessels - rafts, sealed tanks, which are towed to the place of their installation (pipes, tanks, pontoons), delivered on a tug in a floating state of metal structures (oil rigs, bridge spans, etc.).
Based on the study, it was concluded that the Merchant shipping code of Ukraine uses concepts of the same meaning: ship (so-called section II Merchant shipping code of Ukraine and this concept is used in the title of many articles), merchant ship (Part 1 of Article 15 of the Merchant shipping code of Ukraine), sea vessel (Part 1 of Article 13 of the Merchant shipping code of Ukraine). Therefore, to improve the Merchant shipping code of Ukraine, it should be borne in mind that the concepts of «ship», «merchant ship», «sea vessel» are differentiated and have different meanings and relate to each other as general and special.
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Millick, Sujata S. "Design Considerations for Oceanographic Research Vessels." Marine Technology Society Journal 35, no. 3 (September 1, 2001): 8–13. http://dx.doi.org/10.4031/002533201788057937.
Full textAbstract:
As the oceanographic research vessel community prepares for updating its fleet of research vessels, they must consider vessel designs that improve the capability of the fleet to support science in the near and long-term. Advances in informational technologies have changed the "instruments" of science and resulted in the ability to study ocean processes in smaller time and space scales than before. While, networked structures on the ocean floor, remote sensing, and autonomous vehicles will allow oceanographers to synoptically measure the environment, ships will remain the "host-platforms" for such research. However, deployment and recovery of such systems, requires that future designs incorporate capabilities for increased speed, seakeeping, acoustic quietness, efficient power management systems, and lifecycle considerations. Consideration of such issues in the design phases will allow for the development of a technologically advanced ship that can serve the research community in the near and long-term.A major aspect of oceanography through the decades has been the availability of research vessels for science. However, the access to and the capability of such vessels under the University-National Oceanographic Laboratory System (UNOLS) must not be taken for granted. Changes in the oceanographer's ability to make measurements at smaller and smaller sampling scales are brought on by advents in computational and information technologies. These changes necessitate that the researcher's "host-platform" evolves to handle these new observing systems. This evolution can include, but is not limited to speed, seakeeping, efficient ship power arrangements, and acoustic quietness. While each subject can be the focus of detailed individual papers, this article presents a general discussion on four elements of oceanographic research vessel design—hull concepts, power systems, acoustics, and life cycle management.
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Liang, Guo Ming, Zhao Yang Zhang, Yong Ming Chen, and Zhi Min Xu. "Investigation of Laser Shock Processing on the Key Weld Zone of Offshore Platform." Key Engineering Materials 464 (January 2011): 532–36. http://dx.doi.org/10.4028/www.scientific.net/kem.464.532.
Full textAbstract:
Effects of laser power and spot diameter on residual stress and micro-hardness of the welding of ship plate (ASTM A 131) by laser shock processing (LSP) has been investigated. While laser power is 45.9J, spot diameter less thanφ3 mm, the distribution of residual stress in welding line occurs obvious variation, which residual stress compressive increase obviously with spot diameter decrease. When power density is bigger than 1.2×1010 W/cm2, the surface residual stresses and micro-hardness of the welded specimen occur change by LSP. The results show that mechanical properties of the welded joints will be improved by LSP. Laser shock processing produced a residual compressive stress layer on the surface of the target, which is an effective method for protecting the welded steel structures against stress corrosion.
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Wei, Naying, Zhen Zhang, Xu Xu, and Wenjuan Yao. "Stability Analysis of a TLP with Inclined Tension Legs under Different Marine Survival Conditions." Journal of Marine Science and Engineering 10, no. 8 (July 31, 2022): 1058. http://dx.doi.org/10.3390/jmse10081058.
Full textAbstract:
To verify that inclined tension legs can improve the stability of the tension leg platform, this paper established the dynamic equation of a tension leg platform (TLP) under marine environmental loads by using the modified Morrison equation considering the influence of ocean currents on wave forces. Additionally, the velocity and acceleration of random wave water particles were simulated via the JONSWAP spectrum. In addition, a three-dimensional model of a tension leg platform with inclined tension legs was established by AQWA, and its dynamic responses under variable survival conditions were compared and analyzed. The results showed that the surge and heave were more sensitive to the sea current, while the pitch was more sensitive to the wind. There is a significant difference in tendon tensions between the atypical TLP with inclined tension legs established in this study and the typical International Ship and Offshore Structures Committee (ISSC) TLP.
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Hu, Wenqing, Qianming Shang, Xiangrui Bian, and Renjie Zhu. "Energy management strategy of hybrid energy storage system based on fuzzy control for ships." International Journal of Low-Carbon Technologies 17 (December 29, 2021): 169–75. http://dx.doi.org/10.1093/ijlct/ctab094.
Full textAbstract:
Abstract Lithium-ion batteries have high-energy density, but they cannot respond quickly to power fluctuations; supercapacitors (SCs) can quickly respond to power fluctuations, but their energy density is low. The hybrid energy storage system (HESS) that uses both lithium-ion batteries and SCs can take into account the advantages of both, making the system perform better; however, the energy distribution between lithium-ion batteries and SC is difficult. This paper takes ships as the research object, analyzes the power changes of ships during operation, and finds that high-power fluctuations are always only a minority. This paper uses a fuzzy control strategy, based on the actual operating conditions of the ship, except that the ship’s power fluctuation is very small; the SC will provide energy for the ship to make full use of the SC instead of waiting for the arrival of high-power fluctuations. This paper builds an experimental platform and uses the Arbin tester to simulate the operation of the ship. The experimental data show that the SC can have enough time to adjust its state of charge to deal with the power fluctuations at the next moment even if it keeps charging and discharging. The research results of this paper have certain significance for the energy distribution and capacity configuration of HESS.
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Remadevi, M., Gilu K. Abraham, R. Rajesh, and N. Sureshkumar. "Adaptive Tow Ship Noise Cancellation Using Deep Regression Neural Network." Advances in Military Technology 17, no. 2 (August 28, 2022): 179–93. http://dx.doi.org/10.3849/aimt.01522.
Full textAbstract:
This paper investigates the problem of cancellation of noise generated by own platform in shallow water scenario. In the case of underwater acoustics, the target signal detection and tracking in the presence of tow ship noise is a challenging task. A computationally intensive technique is necessary for tow ship noise suppression. In this paper, an algorithm using deep regression neural network (DRNN) along with minimum variance distortionless response (MVDR) beamformer is presented for tow ship noise cancellation. Nine DRNN’s each with different weight initialization techniques and activation functions are designed for effective tow ship noise cancellation. The designed DRNNs is tested using the simulated data and further validated using the real data collected during the trials from Arabian Sea.
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Chen, Hao, Jinke Xie, Jingang Han, Weifeng Shi, Jean-Frédéric Charpentier, and Mohamed Benbouzid. "Position Control of Heave Compensation for Offshore Cranes Based on a Particle Swarm Optimized Model Predictive Trajectory Path Controller." Journal of Marine Science and Engineering 10, no. 10 (October 4, 2022): 1427. http://dx.doi.org/10.3390/jmse10101427.
Full textAbstract:
The wave compensation system can be very useful in several naval applications. It can greatly reduce the relative irregular motion between the two ships when replenishment operations are performed, or between the ship and the offshore platform, which is caused by the waves. It is widely used in offshore operations, offshore cargo transfer, oil and gas exploitation, deep-sea mining, the hoisting and recovery of submersibles, etc. However, when a crane is used in a ship or moving platform, due to the influence of the hull, the crane load movement is similar to a space ball pendulum, which causes the heave displacement to show significant nonlinear motion characteristics. Moreover, the time delay of the detection mechanism and control error could result in untimely compensation, which deteriorates the performance. Consequently, this paper proposes one advanced prediction compensation method, namely Particle Swarm Optimized Model Predictive Trajectory Path controller (PSO−MPTP), which can improve the heave compensation performance. This method, which is based on Model Predictive Control (MPC), is firstly applied to the position servo system and takes into account the heave prediction and control effects simultaneously. The heave displacement of the crane load could be predicted in multiple steps in advance and used as the input of the position loop of the compensation machine. The achieved simulations show that the proposed controller has better prediction ability, higher control accuracy, and stronger robustness.
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Li, Wen, Craig Hancock, Yusong Yang, Jian Wang, and Xiaolin Meng. "Dynamic deformation monitoring of an offshore platform structure with accelerometers." Journal of Civil Structural Health Monitoring 12, no. 2 (December 16, 2021): 275–87. http://dx.doi.org/10.1007/s13349-021-00542-4.
Full textAbstract:
AbstractIn this paper, structural characteristics are evaluated by displacement and frequency indicators that indicate the real-time health status of offshore platforms. This paper uses an accelerometer to collect the dynamic response of the platform in the event of a ship collision. The main contributions of this research are reflected in three aspects. Firstly, based on Empirical Mode Decomposition (EMD) multiscale decomposition, the noise range is determined according to the scale and the average value of the standardized accumulation mode, and the original acceleration sequence is denoised. Secondly, two impact tests were carried out to understand the platform's structural characteristics under an external load. Combined with the FFT algorithm and Hilbert Huang transform, the three-dimensional information of the time, frequency, and energy is analyzed. Finally, a method of high-frequency dynamic displacement reconstruction is proposed. According to the extracted vibration frequency information, the parameters for the filter are reasonably set, and the denoised acceleration time sequence is processed with bandpass filtering and quadratic integration to obtain the high-frequency dynamic displacement of the structure. The results show that the high-frequency dynamic displacement of the accelerometer reconstruction is 1.5 mm. Two collision event frequencies, 1.477 Hz and 1.483 Hz, were successfully extracted from the north direction.
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Dymarski, Czesław, Paweł Dymarski, and Jędrzej Żywicki. "Technology Concept of TLP Platform Towing and Installation in Waters with Depth of 60 m." Polish Maritime Research 24, s1 (April 25, 2017): 59–66. http://dx.doi.org/10.1515/pomr-2017-0022.
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Abstract The article is part of the design and research work conducted at the Gdansk University of Technology, Faculty of Ocean Engineering and Ship Technology, in cooperation with a number of other research centres, which concerns offshore wind farms planned to be built in the Polish zone of the Baltic sea in the next years. One of most difficult tasks in this project is building suitable foundations for each power unit consisting of a tower and a wind turbine mounted on its top. Since the water regions selected for building those wind farms have different depths, there was need to study different possible technical variants of this task, with the reference to both the foundation structures themselves, and the technology of their transport and setting, or anchoring. The article presents the technology of towing, from the shipyard to the setting place, and installation of the foundation having the form of a floating platform of TLP (Tension Leg Platform) type, anchored by tight chains to suction piles in the waters with depth of 60 m.
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Belyaev, Nikolay Dmitrievich, Vladimir Valintinovich Lebedev, Anastasy Valerjevna Mishina, Igor Sergeevich Nudner, Konstantin Konstantinovich Semenov, and Dmitry Igorevich Schemelinin. "Experimental Study of Tsunami-Type Waves Impact on Soil near Foundation of Offshore Gravitational-Type Platforms." Applied Mechanics and Materials 725-726 (January 2015): 306–16. http://dx.doi.org/10.4028/www.scientific.net/amm.725-726.306.
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The need to study the problem of seabed local scour near offshore platforms has arisen in Russian Federation in connection with the activation of oil and gas production from fields located in coastal areas of seas (in accordance with the Energy Strategy for the period up to 2030, approved by the Government of the Russian Federation on November 13, 2009, No1715-p). Operation of offshore platforms is characterized by a number of features: shallow water areas; severe storm conditions; large transverse dimensions of structures that cause waves diffraction; the variety of used structure forms; the way of platform mounting on the seabed. During platform operation in the shallow waters, its basement soil is under an intense impact of sea waves, currents, as well as jets from engine of coming and berthing ships. The structure disturbs the natural wave flow. Near the platform, flow velocity increases, there are vortexes breakaway from platform corner edges. Scour holes appear and progress near platform foundation. Their location and measure depend on the parameters of external impacts, on the water depth, on the shape and dimensions of the foundation block.
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Lei, Chuan, Ming Hong, and Hong Yu Cui. "Modal Parameters Identification of Time-Varying System Based on Hilbert-Huang Transform." Applied Mechanics and Materials 668-669 (October 2014): 1081–85. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.1081.
Full textAbstract:
Mass distribution of floating structures will change due to such factors as ballast water management during ship sailing or inward and outward port, crane movement during construction, and the loading and unloading of cargoes on the offshore platform structures, which will then make its natural frequency change with time. While traditional modal identification cannot deal with the issues of non-stationary of time-varying system, Hilbert-Huang transform is quite effective for the processing and analysis of non-stationary signal. Therefore, this paper investigates the identification of linear time-varying system using the Hilbert-Huang transform, and conducts a numerical simulation of the two degrees-of-freedom time-varying system. In addition, this paper designs a cantilever beam subjected to a moving mass, and then makes a comparison of the identification results between the present identification method and those from finite element method (FEM) and eigensystemrealization algorithm (ERA), which shows a higher accuracy of the present method for modal identification of time-varying system.
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Murawski, Lech, Wieslaw Ostachowicz, Szymon Opoka, Magdalena Mieloszyk, and Katarzyna Majewska. "Practical Application of Monitoring System Based on Optical Sensors for Marine Constructions." Key Engineering Materials 518 (July 2012): 261–70. http://dx.doi.org/10.4028/www.scientific.net/kem.518.261.
Full textAbstract:
The paper presents structural health monitoring (SHM) system, dedicated to marine structures. The considered system is based on the fibre optic technique with Fibre Bragg Grating (FBG) sensors. The aim of this research is recognition of possible practical applications of the fibre optic techniques in selected elements of marine structures. SHM and damage detection techniques have a great importance (economical, human safety and environment protection) in the wide range of marine structures, especially for ships and offshore platforms. In the paper monitoring system of the Horyzont II and Dar Młodzieży ships and offshore oil platform is presented. Practical implementation of safety system based on optical sensors meets several difficulties. There has been installed the FBG system and its measurement results have been compared with classical techniques, e.g. piezoelectric accelerometers. The investigations have been performed for undamaged and damaged structure. Different types of failures have been modelled and tested. Damage detection ability has been specifying on the base of static and dynamic structural characteristics.
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Zheng, Kai, Zengshen Ye, Fanchao Wang, Xi Yang, and Jianguo Wu. "Custom software development of structural dimension optimization software for the buckling of stiffened plates." Electronic Research Archive 31, no. 2 (2022): 530–48. http://dx.doi.org/10.3934/era.2023026.
Full textAbstract:
<abstract> <p>Existing structural optimization software tools only integrate the Euler buckling function of rods and plates and do not consider the buckling strength constraint of stiffened plates, thus failing to meet the optimization design requirements of thin-walled structures such as ship hulls. In this study, according to the buckling strength specifications for stiffened plates of ships, the custom software development of a structural optimization program with "buckling constraints of stiffened plates" was performed using the HyperMesh optimization design software. The finite-element grid of the stiffened plate was divided; the average stress, stress gradient and other parameters associated with the buckling of stiffened plates were determined; the DRESP3 card was set; the external OML function file was linked and the buckling strength of the stiffened plates was introduced into the dimensional optimization design model as a constraint. The proposed method was used to optimize the structure scantlings of a platform, achieving a reduction of 8.96% compared with the original scheme, while also meeting the requirements of structural strength, deformation and buckling strength. The results demonstrated that the dimensional optimization software with buckling constraints is operable and can aid in the rapid structural optimization design of stiffened plates.</p> </abstract>
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Roman, Chris, David S. Ullman, Dave Hebert, and Stephen Licht. "The Wire Flyer Towed Profiling System." Journal of Atmospheric and Oceanic Technology 36, no. 2 (January 29, 2019): 161–82. http://dx.doi.org/10.1175/jtech-d-17-0180.1.
Full textAbstract:
Abstract The Wire Flyer towed vehicle is a new platform able to collect high-resolution water column sections. The vehicle is motivated by a desire to effectively capture spatial structures at the submesoscale. The vehicle fills a niche that is not achieved by other existing towed and repeat profiling systems. The Wire Flyer profiles up and down along a ship-towed cable autonomously using controllable wings for propulsion. At ship speeds between 2 and 5 kt (1.02–2.55 m s−1), the vehicle is able to profile over prescribed depth bands down to 1000 m. The vehicle carries sensors for conductivity, temperature, depth, oxygen, turbidity, chlorophyll, pH, and oxidation reduction potential. During normal operations the vehicle is typically commanded to cover vertical regions between 300 and 400 m in height with profiles that repeat at kilometer spacing. The vertical profiling speed can be user specified up to 150 m min−1. The high-density sampling capability at depths below the upper few hundred meters makes the vehicle distinct from other systems. During operations an acoustic modem is used to communicate with the vehicle to provide status information, data samples, and the ability to modify the sampling pattern. This paper provides an overview of the vehicle system, describes its operation, and presents results from several cruises.
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Reineman, Benjamin D., Luc Lenain, and W. Kendall Melville. "The Use of Ship-Launched Fixed-Wing UAVs for Measuring the Marine Atmospheric Boundary Layer and Ocean Surface Processes." Journal of Atmospheric and Oceanic Technology 33, no. 9 (September 2016): 2029–52. http://dx.doi.org/10.1175/jtech-d-15-0019.1.
Full textAbstract:
AbstractThe deployment and recovery of autonomous or remotely piloted platforms from research vessels have become a way of significantly extending the capabilities and reach of the research fleet. This paper describes the use of ship-launched and ship-recovered Boeing–Insitu ScanEagle unmanned aerial vehicles (UAVs). The UAVs were instrumented to characterize the marine atmospheric boundary layer (MABL) structure and dynamics, and to measure ocean surface processes during the October 2012 Equatorial Mixing (EquatorMix) experiment in the central Pacific and during the July 2013 Trident Warrior experiment off the Virginia coast. The UAV measurements, including atmospheric momentum and radiative, sensible, and latent heat fluxes, are complemented by measurements from ship-based instrumentation, including a foremast MABL eddy-covariance system, lidar altimeters, and a digitized X-band radar system. During EquatorMix, UAV measurements reveal longitudinal atmospheric roll structures not sampled by ship measurements, which contribute significantly to vertical fluxes of heat and momentum. With the nadir-looking UAV lidar, surface signatures of internal waves are observed, consistent and coherent with measurements from ship-based X-band radar, a Hydrographic Doppler Sonar System, and a theoretical model. In the Trident Warrior experiment, the instrumented UAVs were used to demonstrate real-time data assimilation of meteorological data from UAVs into regional coupled ocean–atmosphere models. The instrumented UAVs have provided unprecedented spatiotemporal resolution in atmospheric and oceanographic measurements in remote ocean locations, demonstrating the capabilities of these platforms to extend the range and capabilities of the research fleet for oceanographic and atmospheric studies.
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Klappenbach, F., M. Bertleff, J. Kostinek, F. Hase, T. Blumenstock, A. Agusti-Panareda, M. Razinger, and A. Butz. "Accurate mobile remote sensing of XCO<sub>2</sub> and XCH<sub>4</sub> latitudinal transects from aboard a research vessel." Atmospheric Measurement Techniques 8, no. 12 (December 1, 2015): 5023–38. http://dx.doi.org/10.5194/amt-8-5023-2015.
Full textAbstract:
Abstract. A portable Fourier transform spectrometer (FTS), model EM27/SUN, was deployed onboard the research vessel Polarstern to measure the column-average dry air mole fractions of carbon dioxide (XCO2) and methane (XCH4) by means of direct sunlight absorption spectrometry. We report on technical developments as well as data calibration and reduction measures required to achieve the targeted accuracy of fractions of a percent in retrieved XCO2 and XCH4 while operating the instrument under field conditions onboard the moving platform during a 6-week cruise on the Atlantic from Cape Town (South Africa, 34° S, 18° E; 5 March 2014) to Bremerhaven (Germany, 54° N, 19° E; 14 April 2014). We demonstrate that our solar tracker typically achieved a tracking precision of better than 0.05° toward the center of the sun throughout the ship cruise which facilitates accurate XCO2 and XCH4 retrievals even under harsh ambient wind conditions. We define several quality filters that screen spectra, e.g., when the field of view was partially obstructed by ship structures or when the lines-of-sight crossed the ship exhaust plume. The measurements in clean oceanic air, can be used to characterize a spurious air-mass dependency. After the campaign, deployment of the spectrometer alongside the TCCON (Total Carbon Column Observing Network) instrument at Karlsruhe, Germany, allowed for determining a calibration factor that makes the entire campaign record traceable to World Meteorological Organization (WMO) standards. Comparisons to observations of the GOSAT satellite and concentration fields modeled by the European Centre for Medium-Range Weather Forecasts (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) demonstrate that the observational setup is well suited to provide validation opportunities above the ocean and along interhemispheric transects.
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Yu, Zhaolong, Yugao Shen, Jørgen Amdahl, and Marilena Greco. "Implementation of Linear Potential-Flow Theory in the 6DOF Coupled Simulation of Ship Collision and Grounding Accidents." Journal of Ship Research 60, no. 03 (September 1, 2016): 119–14. http://dx.doi.org/10.5957/jsr.2016.60.3.119.
Full textAbstract:
Ship collisions and groundings are highly nonlinear and transient, coupled dynamic processes involving large structural deformations and fluid structure interactions. It has long been difficult to include all effects in one simulation. By taking advantage of the user-defined load subroutine and the user common variable, this article implements a model of hydrodynamic loads based on linear potential-flow theory into the nonlinear finite element code LS-DYNA, facilitating a fully coupled six degrees of freedom (6DOF) dynamic simulation of ship collision and grounding accidents. Potential-flow theory both with and without considering the forward speed effect is implemented for studying the speed influence. With the proposed model, transient effects of the fluid, global ship motions, impact forces, and structural damage can all be predicted with high accuracy. To the authors' knowledge, this is the first time the fully coupled 6DOF collision and grounding simulations are carried out with linear hydrodynamic loads for transient conditions but without simplification of collision forces. The proposed method is applied to calculations of an offshore supply vessel colliding with a rigid plate and with a submersible platform. The results are compared with a decoupled method and discussed with emphasis on the influence of different initial velocities. The proposed method is capable of predicting both the 6DOF ship motions and structural damage simultaneously with good efficiency and accuracy; hence, it will be a very promising tool in the application to ship collision and grounding analysis.
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Menna, F., E. Nocerino, S. Troisi, and F. Remondino. "JOINT ALIGNMENT OF UNDERWATER AND ABOVE-THE-WATER PHOTOGRAMMETRIC 3D MODELS BY INDEPENDENT MODELS ADJUSTMENT." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-5/W5 (April 9, 2015): 143–51. http://dx.doi.org/10.5194/isprsarchives-xl-5-w5-143-2015.
Full textAbstract:
The surveying and 3D modelling of objects that extend both below and above the water level, such as ships, harbour structures, offshore platforms, are still an open issue. Commonly, a combined and simultaneous survey is the adopted solution, with acoustic/optical sensors respectively in underwater and in <i>air</i> (most common) or optical/optical sensors both below and above the water level. In both cases, the system must be calibrated and a ship is to be used and properly equipped with also a navigation system for the alignment of sequential 3D point clouds. Such a system is usually highly expensive and has been proved to work with still structures. On the other hand for free floating objects it does not provide a very practical solution. In this contribution, a flexible, low-cost alternative for surveying floating objects is presented. The method is essentially based on photogrammetry, employed for surveying and modelling both the emerged and submerged parts of the object. Special targets, named Orientation Devices, are specifically designed and adopted for the successive alignment of the two photogrammetric models (underwater and in <i>air</i>). A typical scenario where the proposed procedure can be particularly suitable and effective is the case of a ship after an accident whose damaged part is underwater and necessitate to be measured (Figure 1). The details of the mathematical procedure are provided in the paper, together with a critical explanation of the results obtained from the adoption of the method for the survey of a small pleasure boat in floating condition.
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Wu, Gongxing, Mingyuan Zhao, Yu Cong, ZhiWen Hu, and Guofu Li. "Algorithm of Berthing and Maneuvering for Catamaran Unmanned Surface Vehicle Based on Ship Maneuverability." Journal of Marine Science and Engineering 9, no. 3 (March 6, 2021): 289. http://dx.doi.org/10.3390/jmse9030289.
Full textAbstract:
In the complex port environment, ship berthing manipulation is one of the most difficult operations. In this study, an algorithm of berthing and maneuvering was designed for a catamaran unmanned surface vehicle (USV), which is used for port patrol and protection. Considering the influence of wind, waves, and currents, the mathematical model of the maneuvering movement for the twin-hull and twin-propeller USV was established. Based on the Visual Studio development platform, the USV’s berthing manipulation simulation software was designed. Through the turning simulation experiment of the catamaran USV under different differential rotation speeds of the twin propellers, the relationship between the ship’s turning radius and the propeller speed difference was obtained. A simulation experiment of decelerating and stopping ships at different speeds was carried out, which can provide a reference for speed control when berthing. A berthing maneuvering algorithm based on ship maneuverability was proposed. USV’s berthing algorithm includes three stages: approach process, turning process, and berthing process. In the approach process, the appropriate approach speed was select according to the rotation angle. In the turning process, the right and left propeller speed differences were select. In the berthing process, the berthing speed was controlled according to the berthing distance. In the port environment, a berthing simulation experiment for catamaran USV was carried out. The simulation results show that based on the berthing and maneuvering algorithm, the efficiency and safety of catamaran USV berthing can be improved.
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Klappenbach, F., M. Bertleff, J. Kostinek, F. Hase, T. Blumenstock, A. Agusti-Panareda, M. Razinger, and A. Butz. "Accurate mobile remote sensing of XCO<sub>2</sub> and XCH<sub>4</sub> latitudinal transects from aboard a research vessel." Atmospheric Measurement Techniques Discussions 8, no. 7 (July 20, 2015): 7413–53. http://dx.doi.org/10.5194/amtd-8-7413-2015.
Full textAbstract:
Abstract. A portable Fourier Transform Spectrometer (FTS), model EM27/SUN, is deployed onboard the research vessel Polarstern to measure the column-average dry air mole fractions of carbon dioxide (XCO2) and methane (XCH4) by means of direct sunlight absorption spectrometry. We report on technical developments as well as data calibration and reduction measures required to achieve the targeted accuracy of fractions of a percent in retrieved XCO2 and XCH4 while operating the instrument under field conditions onboard the moving platform during a six week cruise through the Atlantic from Cape Town (South Africa, 34° S, 18° E) to Bremerhaven (Germany, 54° N, 19° E). We demonstrate that our solar tracker typically achieves a tracking precision of better than 0.05° toward the center of the sun throughout the ship cruise which facilitates accurate XCO2 and XCH4 retrievals even under harsh ambient wind conditions. We define several quality filters that screen spectra e.g. when the field-of-view is partially obstructed by ship structures or when the lines-of-sight cross the ship exhaust plume. The measurements in clean oceanic air, can be used to characterize a spurious airmass dependency. After the campaign, deployment of the spectrometer side-by-side the TCCON (Total Carbon Column Observing Network) instrument at Karlsruhe, Germany, allows for determining a calibration factor that makes the entire campaign record traceable to World Meteorological Organization (WMO) standards. Comparisons to observations of the GOSAT satellite and concentration fields modeled by the European Centre for Medium-Range Weather Forecasts (ECMWF) within the project Monitoring of Atmospheric Composition and Climate – Interim Implementation (MACC-II) demonstrate that the observational setup is well suited to provide validation opportunities above the ocean and along interhemispheric transects.
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Stredulinsky, David C., and Eric M. Thornhill. "Ship Motion and Wave Radar Data Fusion for Shipboard Wave Measurement." Journal of Ship Research 55, no. 02 (June 1, 2011): 73–85. http://dx.doi.org/10.5957/jsr.2011.55.2.73.
Full textAbstract:
Defence Research and Development Canada (DRDC) Atlantic has conducted many dedicated seakeeping and structural load trials on the Canadian Navy research ship CFAV Quest and on several Canadian Navy warships. Typically, wave buoys have been deployed to measure seaway wave characteristics; however, there has been an ongoing interest in evaluating shipboard wave measurement systems. These systems have some advantages over wave buoys for short-term trials and are needed for longer-term sea trials and to provide wave input data for tactical and real-time ship operator guidance systems. This paper presents some of our experiences with wave radar. In the last few years there have been significant advances in wave radar technology (systems that extract wave data from backscatter information contained in the video output of X-band navigational radar displays). Commercial "off-the-shelf" systems are now available. While there is evidence that these systems can provide reliable wave data from shore-based or stationary platform installations, it is DRDC's experience on a ship moving in waves, that wave radars can give good direction and frequency measurements but less reliable wave heights. DRDC has developed a method to improve shipboard wave height measurement through fusion of wave radar data with measured ship motion response data. This paper discusses the development of the wave data fusion process, validated through previous sea trial data, and presents the results of a recent demonstration of the approach during a sea trial conducted on CFAV Quest in November/December 2008.
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Perrault, Douglas Edward. "Probability of Sea Condition for Ship Strength, Stability, and Motion Studies." Journal of Ship Research 65, no. 01 (March 17, 2021): 1–14. http://dx.doi.org/10.5957/josr.05190024.
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Modeling and simulation continues to be an important tool for determining the response of sea-going vessels to wind and waves. To provide appropriate forcing functions to the models, it is important to have environmental data of sufficient fidelity to facilitate an assessment of platform response, which is as accurate as possible within the practical constraints of time and resources. Fortunately, there are a variety of sources of good wave data, including the U.S. National Oceanic and Atmospheric Administration. This study examines the wave data in the context of simulation codes for assessing characteristics of ocean craft response. It also looks at some practical considerations to limit the scope of simulations. The work is strongly influenced by modeling and simulation of naval surface ships, looking for extreme behaviors, but many of the issues discussed are broadly applicable to other applications. Copyright 2021 Her Majesty the Queen in Right of Canada, Department of National Defence
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Holtberget, Simen Hellgren, Xu Xiang, Cato Dørum, Johannes Veie, and Arianna Minoretti. "The Choice of Materials for the E39 Fjord Crossing Project." Nordic Concrete Research 61, no. 2 (December 1, 2019): 39–51. http://dx.doi.org/10.2478/ncr-2019-0016.
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Abstract In the studies for crossing the long and deep Norwegian fjords along the E39 road, on the west coast of Norway, some challenging structures have been evaluated. Some of them are known structures, like floating bridges, and some others are structures never built before, like suspension bridges on tension leg platforms and submerged floating tube bridges. In the development of the feasibility studies for these crossings, the choice of materials has played an important role. The materials influence not only the design and the cost, but also the behaviour of the structure towards the environmental loads and some particular loads as the ship collision. The article illustrates the different solutions proposed for the fjord crossings and discusses the influence in the choice of the material, with special regards to the type of concrete. The pros and cons of the application of the light weight concrete are discussed.
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Zhang, S., C. Liu, and N. Haala. "THREE-DIMENSIONAL PATH PLANNING OF UAVS IMAGING FOR COMPLETE PHOTOGRAMMETRIC RECONSTRUCTION." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences V-1-2020 (August 3, 2020): 325–31. http://dx.doi.org/10.5194/isprs-annals-v-1-2020-325-2020.
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Abstract. Lightweight unmanned aerial vehicles (UAVs) have been widely used in image acquisition for 3D reconstruction. With the availability of compact and high-end imaging sensors, UAVs can be the platform for precise photogrammetric reconstruction. However, the completeness and precision of complex environment or targets highly rely on the flight planning due to the self-occlusion of structures. Flight paths with back-and-forth pattern and nadir views will result in incompleteness and precision loss of the 3D reconstruction. Therefore, multiple views from different directions are preferred in order to eliminate the occlusion. We propose a 3D path planning method for multirotor UAVs aiming at capturing images for complete and precise photogrammetric 3D reconstructions. This method takes the coarse model from an initial flight as prior knowledge and estimates its completeness and precision. New imaging positions are then planned taking photogrammetric constraints into account. The real-world experiment on a ship lock shows that the proposed method can acquire a more complete result with similar precision compared with an existing 3D planning method.
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Chen, Yongjun, Wenhao Wu, Pengfei Jiang, and Chengpeng Wan. "An Improved Bald Eagle Search Algorithm for Global Path Planning of Unmanned Vessel in Complicated Waterways." Journal of Marine Science and Engineering 11, no. 1 (January 5, 2023): 118. http://dx.doi.org/10.3390/jmse11010118.
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The path planning of unmanned ships in complex waters using heuristics usually suffers from problems such as being prone to fall into the local optimum, slow convergence, and instability in global path planning. Given this, this paper proposes a Self-Adaptive Hybrid Bald Eagle Search (SAHBES) Algorithm by incorporating adaptive factors into the traditional BES in order to enhance the early global searching ability of the BES algorithm. Moreover, Pigeon-Inspired Optimization (PIO) is introduced to overcome the disadvantage of traditional BES algorithms: that it is easy for them to fall into local optimization. This study improves the fitness function by adding a distance between the ships’ path corners. The obstacle is based on the calculation of the path length. The curve optimization module is applied to smooth the obtained path to generate more rational path planning results, which means the path is the shortest and avoids collision successfully. A simulation test of the SAHBES algorithm on the path planning under different obstacle scenarios is conducted by using the MATLAB platform. The results show that SAHBES can generate the shortest safe, smooth path in different complex water environments, considering the limitations of fundamental ship maneuvering operations compared to other algorithms, thus verifying the feasibility and efficiency of the proposed SAHBES algorithm.
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Dalheim, Øyvind Øksnes, and Sverre Steen. "Added Resistance and Speed Loss of a Ship Found Using Onboard Monitoring Data." Journal of Ship Research 64, no. 02 (June 1, 2020): 99–117. http://dx.doi.org/10.5957/jsr.2020.64.2.99.
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Prediction of the added resistance or corresponding speed loss in real sea conditions is essential to evaluate the performance of a ship. Assessment of the environmental impact on vessel performance is essential for route and cargo planning, optimization of fuel consumption and design, and configuration of engines and the main propulsion system. In the present study, added resistance and speed loss in real sea conditions are evaluated from1 year of onboard monitoring data of a platform supply vessel (PSV) operating in the North Sea. The true sea margin is shown on an annual basis. Relative contributions from environmental conditions and vessel operation control are presented. Results are compared with model experiments and existing numerical methods for prediction of added resistance and speed loss in waves. The study shows that added resistance due to waves for this PSV is significantly larger than predicted by conventional frequency-domain calculations or model tests. No reason for the deviation is found, but it is anticipated that a combination of effects of longitudinal mass radius of gyration, differences in wavelength and steepness in model tests and reality, and nonlinear effects (not accounted for in the numerical calculations) is partly responsible for the deviations. For ships having similar main dimensions, the conventional ways of predicting added resistance or speed loss in waves is nonconservative, and improved methods should be sought.
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Sarjito, Aris. "PESTLE Analysis of Production Management Landing Platform Dock Warship PT PAL Indonesia (Persero) For National Defense." Advances in Social Sciences Research Journal 7, no. 11 (December 2, 2020): 368–86. http://dx.doi.org/10.14738/assrj.711.9329.
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ABSTRACT
Purpose: The purpose of this study is to analyze the production management of PT PAL Indonesia (Persero) 's LPD vessel using PESTLE analysis.
Study Design: This research is descriptive and uses a qualitative approach.
Methodology: This study uses a qualitative analysis approach aimed at PT PAL Indonesia (Persero) 's LPD ship production management.
Place and Duration of Study: This research was conducted in Jakarta and Surabaya in August - October 2020.
Results: (1) PT PAL Indonesia (Persero) is a strategic industry that produces the main equipment of the Indonesian defense system, especially for the marine dimension, (2) the Indonesian Navy relies on PT PAL Indonesia (Persero) to produce LPD-type vessels which are very important to implement sea operations, (3) PT PAL Indonesia periodically measures the implementation and implementation of GCG, as regulated in the Regulation of the Minister of State for SOEs, (4) PT PAL Indonesia (Persero) collaborates with financial institutions and consultants to provide a funding scheme from the capital structure of soft loan provision , insurance and other forms of funding, (5) In the field of general engineering, companies make heavy industrial components such as power plants, diesel engines, steel structures, such as oil and gas industrial equipment, (6) PT PAL Indonesia (Persero) continuously improve the quality of technology and ensure that the products built follow state-of-the-art developments technology, and (7) PT PAL Indonesia (Persero) always strives to provide benefits to society by implementing real corporate social responsibility for the development of harmonious relationships with the community through Corporate Social Responsibility (CSR).
Keywords: economy, environment, legal, political, sociocultural, technology