The development of sensors and control and command modules capable of extracting environmental data has made it possible to build an underwater drone for monitoring and collecting water samples from hard-to-reach areas. In this paper we present the project that focuses on the fundamental challenges related to communication, control but also the analysis of water parameters in real time.
Improving corrosion resistance represents a highly interesting topic in the maritime field, having important economic consequences by reducing the maintenance costs or increasing the life expectancy of the final products and by imposing significant environmental impact. In accordance with new IMO (International Maritime Organization) regulations, different new clean technologies have been proposed for solving this particular issue, among them being also considered the technology based on plasma discharges, generally produced at reduced pressure. The proposed study concerns the opportunity of atmospheric plasma treatment for naval steel preparation or conditioning. Five different treatments, with three types of plasma working under different gases, have been used. Their effects were evaluated based on surface modification analysis. These analyses concern the roughness of the samples and the surface hydrophobicity at two different moments of time. There were used three types of reactors producing non-thermal plasma: GlidArc, Gliding Spark and Minitorch.
For the naval field there are two major problems related to the existence of microorganisms: the deposition of Biofouling and the treatment of ballast water. The first problem is strictly related to corrosion with an important economic impact on maintenance costs. In accordance with new IMO (International Maritime Organization) regulations, different green technologies have been proposed for solving this particular issue, among them being also considered the technology based on plasma discharge produced at low pressure. The proposed study concerns the opportunity of atmospheric plasma treatment for naval steel preparation or conditioning. Five different treatments, with three types of plasma working under different gases, have been used. Their effects were evaluated based on microbiological analysis. These analyses concern the biological contamination of each sample by bacteria control at 2 different moments of time. For this purpose, the Gram-negative bacteria Escherichia coli has been used, because it is one of the most important microbial indicators according to Ballast Water Performance Standard D2 (http://www.imo.org). Three different types of electric discharges were used as non-thermal plasmas for the surface treatment.
Biofouling is the most important cause of naval corrosion. In order to reduce the Biofouling development on naval materials as steel or resin, different new methods have been tested. These methods could help to follow the new IMO environment reglementations and they could replace few classic operations before the painting of the small ships. The replacement of these operations means a reduction in maintenance costs. Their action must influence especially the first two steps of the Biofouling development, called Microfouling, that demand about 24 hours. This work presents the comparative results of the Biofouling development on two different classic naval materials, steel and resin, for three treated samples, immersed in sea water. Non-thermal plasma, produced by GlidArc technology, is applied to the first sample, called GD. The plasma treatment was set to 10 minutes. The last two samples, called AE9 and AE10 are covered by hydrophobic layers, prepared from a special organic-inorganic sol synthesized by sol-gel method. Theoretically, because of the hydrophobic properties, the Biofouling formation must be delayed for AE9 and AE10. The Biofouling development on each treated sample was compared with a witness non-treated sample. The microbiological analyses have been done for 24 hours by epifluorescence microscopy, available for one single layer.
The paper presents an original analytical model of the hydrodynamic loads applied on the half-bridge of a circular settling tank. The calculus domain is defined using analytical geometry and the calculus of the local dynamic pressure is based on the radius from the center of the settling tank to the current area, i.e. the relative velocity of the fluid and the depth where the current area is located, i.e. the density of the fluid. Calculus of the local drag forces uses the discrete frontal cross sectional areas of the submerged structure in contact with the fluid. In the last stage is performed the reduction of the local drag forces in the appropriate points belonging to the main beam. This class of loads is producing the flexure of the main beam in a horizontal plane and additional twisting moments along this structure. Taking into account the hydrodynamic loads, the results of the theoretical models, i.e. the analytical model and the finite element model, may have an increased accuracy.
Corrosion in marine environment is a complex dynamic process influenced mainly by physical chemical, microbiological and mechanical parameters. Times for maintenance related to corrosion are greater than 80% of the total repair. Reducing this cost would be a significant saving, and an effective treatment can reduce times related to ships repairing. Biofouling is a main cause of corrosion and its formation contains four steps. To inhibit biofouling it is proposed a treatment based on non-thermal plasma produced by GlidArc, which can be applied before the immersion of small boats in the sea, as well as cleaning treatment of the hull after a period of time. This work presents the microbiological results of treatment of metal surfaces (naval OL36 steel) with GlidArc technology, according to the first, respectively the second phase formation of biofouling. Samples of naval steel were prepared with three specific naval paints and before the treatment have been introduced in seawater. Microbiological results have been compared for two types of treatments based on GlidArc. In the first case the painted samples are submitted to direct action of non-thermal plasma. In the second case the plasma produced by GlidArc technology is used to activate a solution (plasma activated water = PAW) and then the samples are introduced into this water.
Corrosion in marine environment is an actual problem, being a complex dynamic process influenced mainly by physical, chemical, microbiological and mechanical parameters. Around 70% of the maintenance costs of a ship are associated with the corrosion protection. Times for maintenance related to this phenomenon are greater than 80% of the total repair. Reducing this cost would be a significant saving, and an effective treatment can reduce times related to ships repairing. Biofouling is a main cause of corrosion and for its reduction different methods could be applied, especially in the first part of its production. The atmospheric pressure non-thermal plasmas have been gaining an ever increasing interest for different biodecontamination applications and present potential utilisation in the control of biofouling and biodeterioration. They have a high efficiency of the antimicrobial treatment, including capacity to eradicate microbial biofilms. The adhesion microbial biofilm is mainly influenced by presence of bacteria from the liquid environment. That is why this work concerns the study of annihilation of maximum amount of bacteria from sea water, by using GlidArc technology that produces non-thermal plasma. Bacteria suspended in sea water are placed in contact with activated water. This water is activated by using GlidArc working in humid air. Experimental results refer to the number of different activated and inactivated marine organisms and their evolution, present in solution at certain time intervals after mixing different amounts of seawater with plasma activated water.
Optical methods in experimental mechanics are important because their results are accurate and they may be used for both full field interpretation and analysis of the local rapid variation of the stresses produced by the stress concentrators. Researchers conceived several graphical, analytical and numerical methods for the experimental data reduction. The paper presents an original computer method employed to compute the analytic functions of the isostatics, using the pattern of isoclinics of a photoelastic model or coating. The resulting software instrument may be included in hybrid models consisting of analytical, numerical and experimental studies. The computer-based integration of the results of these studies offers a higher level of understanding of the phenomena. A thorough examination of the sources of inaccuracy of this computer based numerical method was done and the conclusions were tested using the original computer code which implements the algorithm.
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