Papers by Keyword: Ship

Abstract: The paper presents statistics of navigation events occurring on the Romanian sector of the Danube, in general and focused on those whose consequences represented a potential danger of pollution of the Danube water.The information presented and analysed shall be based on publicly available information provided and made available by the relevant competent authorities.The large amount of cargo transported per transport unit (approximately 1000 tons) can cause pollution with the most adverse consequences for the marine environment, but also for live animals and vegetation in the event of a navigation accident. Improper handling of cargo in oil terminals can also lead to accidental pollution with major consequences for the environment, for live animals and vegetation.Thus, involuntary stranding, collision between two ships, fire on board are direct sources of pollution when the integrity of the hull is affected, and fuels, lubricants, greases on board, and or cargo end up in the marine environment.The actions carried out to eliminate the consequences of pollution on the Danube from ships have different aspects and methods of intervention depending on the area where the pollution occurred, the polluting.

Abstract: The use of viscoelastic sheets in the hull of vessels built from GFRP has been raised in previous works as an option to protect the vessel from the destructive damage of slamming. The present work proposes its use in boats previously built by adhering to the outside of the hulls of the ships. Its installation process is shown, and this new type of installation is compared. Through impact tests with GFRP panels, it is shown that the viscoelastic material maintains its property of absorbing slamming energy and protecting the interior of the laminate. Fatigue tests on the order of 5x10⁴ cycles are carried out to evaluate the impact force, the accelerations that deform the laminate and the virtual energy work imposed on the panel. This option shows that designers have a new option to protect the hull of already built boats.

Abstract: In this paper we present the current situation related to the legislative framework on the definition of generated waste by ships in the field of maritime navigation and inland waterway navigation, their management on board ships, handover to port facilities and results in the development of proposals to support participants in the shipping activity in the field of pollution prevention of the Romanian Danube sector. The purpose of the paper is to contribute to the improvement of the current measures that are applied in the field of prevention of pollution of the Romanian Danube sector by ships.

Abstract: The foam core sandwich composite ship is a new kind ship using special materials. The advantages include easy molding, short construction period and so on. However, due to the specialty of the material property as well as the complexity of structures, there are element applicability and calculation efficiency problems when conducting FEA (Finite Element Analysis) calculations of the whole ship. Based on experiment and simulation result, a sandwich shell element is found which is equivalent to the solid element of beam and plate. An efficient and practical way is developed using this equivalent shell element to calculate a catamaran including the analysis of the structure responses in different working conditions. This methodology has a great reference value when conducting computer simulation calculation of foam core sandwich composite ships and marine structures.

Abstract: Composites are getting more and more attention in the usage of major structures on ships owing to many advantages such as high specific strength and rigidity. However, composites are sensitive to impact, which indicates that the load-carrying capacity and stability of composite structures will decrease dramatically even for an invisible impact damage. Hence, a real-time impact monitoring system which has already been applied in aviation industry is important for reliability of ships, which inevitably encounter impacts during their lifetime due to different sources. This paper deals with the realization of an operational processing scheme to monitor the impact on composite structures, and estimate the impact location and load history by power distribution approach and system identification method. A PZT (piezoelectric lead zirconate titanate) sensor network was designed and employed to collect sensing signals for monitoring the impact. In the monitoring process, stress wave signals caused by impact were captured, and used to determine the impacted location and load history. Results demonstrate that the proposed method can be successfully applied in identifying the location and load history of impact on composite structures. The impact identification approach is of great significance for marine applications.

Abstract: By signature gathering system, the shaft-frequency electric field of ship’s physical scale model is measured. At the same time, the mechanism of the corrosion related to shaft-frequency electric field is also described. Results show that the shaft-frequency electric field signature arises around a vessel and transmits in the surrounding seawater due to the current flow from impressed current cathodic protection (ICCP) system and the current flow resulting from the corrosion of dissimilar metals during propeller rotation, which contains both shaft fundamental and harmonics. The signature character of electric field is more and more marked with the shaft rotation speed increasing. The amplitude of electric shaft-frequency electric field by modulating the current of ICCP system is 10 times greater than that of corrosion current. It is proved that the using a 1:100 physical scale model of a vessel to study the shaft-frequency electric field character is an effective method and provided an new way.

Abstract: Increased focus on reducing CO₂ emissions has created growing interest in CO₂ capture from industrial processes for storage in underground formations. New technical solutions, costs and energy requirements for ship-based transport of CO₂ are presented. All elements in the transport chain, namely liquefaction, storage, loading system, dedicated CO₂ ship (s), onshore loading and unloading, and offshore unloading systems are included in the paper. Over 80 % from the primary energy consumed all over the world is obtained from fossil oil and natural gas. The last researches have shown the energy dependences of these types of fuels. The transition to the economy based on the low influence of the carbon, the carbon capture technology, is the main means to reconsider the fossil fuels for meeting the needs for reduction of negative emissions. This is necessary for keeping the world temperature at normal levels. The main target of this paper is to put highlight the negative effect of CO₂ emissions and the interest in recovery of carbon dioxide from flue gases trough multiple factors: the merchant CO₂ market, renewed interest in enhanced oil recovery, and the desire to reduce greenhouse gas emissions. It also takes in account modalities of transport and storage of CO₂. Solutions for CO₂ capture and injection into caverns instead of natural deposits were found worldwide. These solutions are not applicable however all over the world and they are not a priority in the environment protection activity.Another important aspect calls for all merchant ships requirements regarding CO₂ emissions through index calculation and development of Management Plan. Also, to increase the control of CO₂ it would be useful to identify the caverns where it is possible to deposit the CO₂, to build new special ship for CO2 transport or replace natural deposits through CO₂ injection.

Abstract: In this paper, we will select and use stepper motor which is comparatively important and widely used in ships for the study. Through the study, we can propose a method that we can use the synchronous repeater compass for the high-precision digital conversion, and then statistics will be put into SCM AT89C52 with the simple handling of circuit conversion, thus, we can take a series of processes, such as data processing, initial value setting, directional displaying and serial port outputting. Foremost, the precision of this converting circuit can reach 0.1°that can ensure the numbers continuously change behind the decimal point one digit. So it is not only inexpensive, but also flexible and convenient in use.

Abstract: For numerical simulation of ship airwake by CFD, based on the use of an unstructured grid, the k-ε turbulence model and SIMPLE algorithm, the characteristic features of complex fluid flows eg recirculation zones and strong vortex fields in the aircarft operating region of a generic 3D frigate model was presented. The accuracy of the predication was checked by performing calculations on different grid sizes and comparing with wind-tunnel flow visualization data. A comparison of several typical spatial discretization schemes was performed. y⁺ values were also tested. The general features of the flow predicted in this paper compare reasonably well with experimental data. However, CFD simulation produced a higher velocity in the vicinity of vortex zone when compared to experimental data. Obvious differences exist between results by first-order upwind scheme (power law scheme) and second-order upwind scheme (QUICK scheme, third-order MUSCL scheme). Second-order upwind scheme (QUICK scheme, third-order MUSCL scheme) are recommended for the CFD simulation of ship airwakes with a modest increase in computational cost. y⁺ values from o (10) to o (1000) can all be accepted for the CFD simulation of ships (e.g., SFS1 ) with Reynolds number 10⁸ or more.

Abstract: To reduce the impact of shaft-rate electric field (SRE) on the concealment of the ship, the SRE related ship electrical equivalent model is established, and the electrical properties are studied based on the analysis of the mechanism of SRE of the ship in this paper. The ship SRE real-time suppression is proposed based on the compensated negative potential and the real-time close-loop system for the ship SRE suppression is designed. The extremely low frequency electric field strength is reduced greatly, and the shaft-rate and its harmonics field are eliminated ultimately. Experimental results show that the ship SRE can be suppressed effectively by the system, and the concealment of the ship is enhanced.