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Odessa, Ukraine

The article presents a description and physical evaluation of a method of flaw detection of solid structures, for example, walls, pillars, and substructures, made of refractory materials and brick masonry using as an example an investigation of concrete structures. Using the method it is possible to perform flaw detection of concrete with different fillers, including porous fillers, for example, concrete claydite. This brings the subject of flaw detection of concrete close to that of flaw detection of brick masonry and structures made of refractory materials. The method is based on local excitation of standing waves across a wall by means of multiple shock pulses. The experimental data obtained confirm that standing waves are not excited once there is a definite number of defects present, i.e., a process of complete damping of the waves occurs. © 2015 Springer Science+Business Media New York Source

Wang Z.,South China University of Technology | Lv S.,South China University of Technology | Feng J.,South China University of Technology | Sheng Y.,Marine Engineering Bureau
Proceedings of the 2012 4th International Conference on Intelligent Human-Machine Systems and Cybernetics, IHMSC 2012

In this paper, a digital image watermarking algorithm based on chaos and Fresnel transform is proposed. The original image is transformed into Fresnel diffraction plane by distance parameter, and watermark information is embedded in its amplitude spectrum after scrambled by chaotic sequence. The watermark information can be extracted without original image, and there is little influence on the original image after embedding. Chaotic scrambling can encrypt watermark information, and Fresnel transform can provide different diffraction planes with different parameters, so attackers couldn't get right watermark information without knowing the parameters in these two processes. During the experiments, the algorithm is also robust against various common attacks, such as filtering, adding noise, JPEG compression and crop and so on. Experimental results show that this watermarking algorithm can provide enough invisibility, security and robustness. © 2012 IEEE. Source

Egorov G.V.,Marine Engineering Bureau
Developments in Maritime Transportation and Exploitation of Sea Resources - Proceedings of IMAM 2013, 15th International Congress of the International Maritime Association of the Mediterranean

Basic designing principles of dry-cargo vessels and tankers hulls of river-sea going type that have been built during 2001-2010 are considered. It is shown that all these vessels are designed with fully use of locks dimensions of internal water-ways, maximum possible block coefficient with providing best propulsion qualities, increased tonnage with minimum possible depth; increased controllability in constrained conditions and in shallow water; grounded operating reliability of hull construction with optimum specific quantity of hull metal. © 2014 Taylor & Francis Group, London. Source

Bitner-Gregersen E.M.,DNV GL | Bhattacharya S.K.,University of Madras | Chatjigeorgiou I.K.,National Technical University of Athens | Eames I.,University College London | And 9 more authors.
Ocean Engineering

A review of the recent progress made regarding ocean environmental data and models with uncertainties in focus is given in the perspective of marine structures' design and operations. Uncertainties of wind, waves, current, sea water level and ice data and models are discussed and recent achievements leading to improvement of their accuracy are addressed. The study includes mathematical, probabilistic, empirical and statistical models. Particular attention is given to rogue waves. Challenges related to wind data and models due to the increase of offshore wind energy installations are presented focusing on wind forecast, information about the wind profile and extreme wind events. Attention is also given to ice which is of particular importance due to the projected climate changes opening new opportunities in the Arctic regions for the marine industry. Impacts of improved accuracy of environmental description on design and operations of ships and offshore structures are highlighted. © 2014 Elsevier Ltd. All rights reserved. Source

Karlinsky S.L.,Marine Engineering Bureau | Chernetsov V.A.,Marine Engineering Bureau
Proceedings of the International Offshore and Polar Engineering Conference

It is well known, that floating moored platforms resistance to action of an iceberg is problematic. Usually, an impact of an iceberg or a floating "stamukcha" (i.e. iceberg of salt ice) upon a floating facility is assumed to be irresistible due to a lack of a capacity of the mooring system. In such a case accident preventive measures should be undertaken. These measures imply disconnection of the mooring/riser systems from the turret and the relegation of the iceberg by tow vessels or by the FPU own propulsive devices (thrusters). The disconnection procedures are complicated and dangerous and may be too late. Also a failure or malfunction of the disconnection system may arise. In this case an iceberg impact is inevitable and should be examined. As a first approximation it may be proposed that an impact of an iceberg with a limited weight may be compensated by absorption of its kinetic energy by the FPU mooring system with thrusters assistance. Also, the energy absorption by the FPU rotation (yaw) due to eccentric contact impact should be taken into account. The proposed paper demonstrates that the performance mentioned above can be successfully achieved in the turret moored FPU, owing to the performance of the station-keeping system and the turret rotation capacity supported by the FPU thrusters action (also flexible risers system safety taking into account). Here the problem is not only to absorb the energy but also to protect the mooring lines and risers against a direct action of underwater ice features of the iceberg. Copyright © 2010 by The International Society of Offshore and Polar Engineers (ISOPE). Source

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