The effect of sloshing on the sway motions of 2D rectangular cylinders in regular waves

In this paper, we investigated the effect of sloshing on the sway motions of two-dimensional rectangular cylinders in regular waves, bearing in mind possible applications for LNG-FPSO and LNG-FSRU. First, we carried out experiments for two models with different drafts, or the same draft but different filling ratios, in which the models were firmly connected to each other. The sway motion was measured with a noncontact video camera. This is an extension of Rognebakke and Faltinsen’s work for a single model (J Ship Res 47(3):208–221, 2003). It was found that the sway motion became small when the incident wave frequency was close to the lowest natural frequency of each model. The sway motion greatly increased when the wave frequency was higher than this frequency. The measured data were compared with numerical results obtained by a single-dominant multi-modal method; relatively good agreement was noted. However, the numerical results deviated from the experimental results near the lowest natural frequency of the smaller model, which was believed to be due to overturning waves, as observed during the experiment. Since this is out of the valid range for the single-dominant multi-modal method, other, more appropriate, methods such as the multi-dominant modal method must be applied instead.     

Fatigue crack growth behaviour of A5083 series aluminium alloys and their welded joints

We investigated the difference in fatigue behaviour between the aluminium alloys A5083-O and A5083-H321, which are used as structural components in ships and high speed craft. We obtained S–N curves for the base materials and the welded joints made of A5083-O. The relationships between the fatigue crack propagation rates and the stress intensity factor ranges ΔK, ΔK _eff and ΔK _RPG (Toyosada et al. in Int J Fatigue 26(9):983–992, 2004) were determined. Additionally, the evolution of fatigue crack growth for the base materials and the welded joints made of A5083-O was measured. We also carried out numerical simulations of fatigue crack growth for both base metals and their welded joints made of A5083-O. The difference in fatigue crack growth behaviour for each alloy and the validity of the numerical simulations of fatigue crack growth based on the RPG stress criterion (Toyosada et al. 2004) in the base materials and their welded joints was investigated.     

Configuration estimation method for preliminary cost of ships based on engineering bills of materials

Ships are complex engineering structures that are designed and built on the basis of technical experience. A shipowner will often be required to estimate the price of a new ship on the basis of the value of comparable ships identified in trade journals. Similarly, shipbuilders are often interested in estimating approximate costs during the tendering phase in order to determine whether a ship is likely to be competitive for a particular order. Thus, when designing a ship prior to having obtained a contract, one of the most important processes is the estimation of approximate costs, including materials, associated labor, and overhead. During this preliminary design phase, the design is temporary and subject to change based on variations in the shipowner’s requirements. Hence, quick and flexible responses are key during this period and an integral aspect of the competitive powers of the shipbuilder. Given this environment, we propose a “configuration estimation method.” Our method is based on the configuration design method that is widely used in three-dimensional (3D) computer aided design (CAD) systems. We assume that a product lifecycle management system is furnished and that the cost is then estimated via the configuration of the ship, using an engineering bill of materials (E-BOM). In referring to the E-BOM, we utilize technical parametric costs derived from similar ships built previously. Using the proposed method, it is possible to obtain an accurate list of materials from the quotation, as well as a detailed work assessment for labor costs and overhead rates, so that reliable cost estimates can be generated quickly and flexibly. To demonstrate the practical applicability and effectiveness of the proposed method, we implement the prototype of a shipbuilding configuration estimation system by using a Microsoft Structured Query Language database and an E-BOM from AVEVA Marine version 12.01, which is a representative CAD system for shipbuilding.     

Experimental investigation on the drag reducing efficiency of the outer-layer vertical blades

An experimental assessment has been made of the drag reducing efficiency of the outer-layer vertical blades, which were first devised by Hutchins and Choi (Proceedings of ASME FEDSM’02 2002 ASME Fluids Engineering Division Summer Meeting, Montreal) and Hutchins (An investigation of larger-scale coherent structures in fully developed turbulent boundary layers, Hutchins N (2003), PhD thesis, University of Nottingham). The reported drag reduction efficiency, which was as much as 30%, was quantified only in terms of the reduction in the local skin-friction coefficient. The assessment of the drag reducing efficiency did not take the side effects of the inclusion of the blades into considerations. Those effects are the increase in the wetted surface area and the flow disturbances due to the presence of the blades. In the present study, a series of drag force measurements in towing tank has been performed toward the assessments of the total drag reduction efficiency of the outer-layer vertical blades. It was found that for the case of h 4.0 × z 4.0 (h/δ = 1.04), the outer-layer vertical blades array achieved about 9.6% drag reduction without considering the increase in the wetted surface area. A proper scaling method to give collapsed plot of drag reduction efficiency C _F/C _F0 was attempted, but the correlation remained limited. Of the two scaling methods, the outer scaling is found to be relevant one.     

Modelling multiple yacht sailing interactions between upwind sailing yachts

An approach for enhancing the realism of yacht fleet race simulations based on a lifting line method is developed. The wake of an upwind sailing yacht is represented as a single heeled horseshoe vortex and image system. At each time step, changes in vortex strength are convected into the wake as a pair of vortex line elements. These subsequently move in accordance with the local wind, the self-induced velocity and the velocity induced by the presence of the wakes of other yachts. In addition, the lifting line model has a model for the viscous wake due to the drag associated with the yacht and its sails superimposed on it. A synthesis of sail yacht wake representations based on detailed 3D Reynolds-averaged Navier–Stokes computational fluid dynamics calculations with wind tunnel test results is used to capture the initial strength of the combined main-jib vortex system and its vertical height. The implementation of the lifting line algorithm within Robo-Race, a real-time yacht race strategy analysis tool, is described. Two upwind race interaction case studies are presented, and these show that the newly implemented wake model makes an important contribution to enhancing the realism of the sailing simulation.     

The Maritime Labour Convention, 2006—reflections on challenges for flag State implementation

This paper begins by providing a brief overview of the International Labour Organization’s Maritime Labour Convention, 2006 (MLC, 2006), noting that this Convention, often called the “Seafarers’ bill of rights”, seeks to achieve both social and labour rights (“decent work”) for seafarers and fair competition (achieving a level-playing field) for shipowners. It has been described as the “fourth pillar” of the international maritime regulatory regime complementing the major International Maritime Organization conventions. The paper provides a brief update on international efforts to achieve the 30/33 formula needed to bring the Convention into force [at present, the tonnage element, 33% has been achieved already with coverage now at 54% of the world fleet (by gross tonnage), with 18 ratifications]. It then explores challenges faced by flag States in connection with capacity to implement the ship inspection and certification system under the MLC, 2006 and other difficulties with respect to legal implementation by the flag States. The paper also comments on some challenges in connection with port State, coastal State and labour-supplying State responsibilities. The paper points out that the MLC, 2006 is a comprehensive code that covers diverse issues and a wider range of both ships and seafarers than previous conventions. It often requires interdepartmental cooperation to implement its requirements at the national level. The paper concludes that, despite the slower pace of ratification in some regions, largely because of the recent economic and other crises, it appears that many actors in the maritime sector are already actively engaged in MLC, 2006 implementation, often ahead of governments. The question is not “if” but “when” the formula will be achieved to allow the MLC, 2006 to enter into force.     

e-Navigation and situation-dependent manoeuvring assistance to enhance maritime emergency response

Safe ship handling in every situation and under all prevailing circumstances of ship status and the environment is a core element contributing to the safety of the maritime transportation system. Especially in case of emergencies, there is a need for quick, accurate and reliable information to manoeuvre a ship safely. This paper focusses on investigations into enhanced response to maritime emergencies by means of onboard manoeuvring support. The research and discussions are done exemplarily for person overboard (PoB) accidents. PoB is a typical situation for application of manoeuvring assistance and decision support, e.g. in order to return quickly to the position of the accident. Based on the analysis of selected accident case studies and existing solutions representing the technical state-of-the-art, shortcomings will be identified and discussed, and a potential approach for advanced manoeuvring support in the context of e-Navigation-based requirements will be introduced and discussed.     

Analytics: The real-world use of big data in financial services studying with judge system events

“Big data” which admittedly means many things to many people is no longer confined to the realm of technology. Today it is a business imperative and is providing solutions to long-standing business challenges for banking and financial markets companies around the world. Financial services firms are leveraging big data to transform their processes, their organizations and the entire industry. Since 2012, the term “big data” has frequently been mentioned and used to describe and define the huge amount of data in the information explosive era and to name related technological development and innovation. As to the police work, the coming of big data era is not only a challenge but also an opportunity. Police agencies should go with the tide of development to start with such aspects as work thinking, top design, public information sharing and application and talent provision so as to promote the new development and progress of police work. This paper expounds the practical effect and significance of police big data application by cases happened in some areas.     

On-line adaptive repetitive controller for power factor correction systems

When the fundamental frequency is shifting, it is hard for traditional repetitive controller to work at the resonant frequencies. In this paper, a novel adaptive repetitive controller for power factor correction systems is proposed to suppress the current harmonics. Through the controller, the shifting sampling times of the repetitive controller in a fundamental period can be obtained. Mathematical analysis, simulations and physical experiments have validated the effectiveness of the adaptive repetitive controller.     

Saliency motivated pulse coupled neural network for underwater laser image segmentation

The detection range of underwater laser imaging technology achieves 4—6 times of detection range of conventional camera in intervening water medium, which makes it very promising in oceanic research, deep sea exploration and robotic works. However, the special features in underwater laser images, such as speckle noise and non-uniform illumination, bring great difficulty for image segmentation. In this paper, a novel saliency motivated pulse coupled neural network(SM-PCNN) is proposed for underwater laser image segmentation. The pixel saliency is used as external stimulus of neurons. For improvement of convergence speed to optimal segmentation, a gradient descent method based on maximum two-dimensional Renyi entropy criterion is utilized to determine the dynamic threshold. On the basis of region contrast in each iteration step, the real object regions are effectively distinguished,and the robustness against speckle noise and non-uniform illumination is improved by region selection. The proposed method is compared with four other state-of-the-art methods which are watershed, fuzzy C-means, meanshift and normalized cut methods. Experimental results demonstrate the superiority of our proposed method to allow more accurate segmentation and higher robustness.