Search results for "Mooring"
showing 10 items of 20 documents
Fatigue of Mooring Chains Connected to Offshore Floating Structures Considering Out of Plane Bending Effects
2019
Abstract Reliability against fatigue fracture is an issue of major concern in the design of offshore mooring systems with chain segments. The present paper describes the investigation of the effect of OPB (out of plane bending) and IPB (in plane bending) loading modes on the fatigue performance of chain links in critical positions. The hang-off design at the floater is based on long rods with bearings at the connection points to the floating structure. The purpose of the paper is to shed some light on possible design improvements on the connection design when using the available design guidelines for calculation of combined Tension-Bending fatigue in the mooring line. A challenge when using…
Autonomous Mooring towards Autonomous Maritime Navigation and Offshore Operations
2020
Bollard is a vital component of mooring system. It is the anchor point for mooring ropes to be fixed in order to secure the vessel or ship. An algorithm that translates the segmented mask of bollard output from masked R-CNN along with bounding box and associated class probability to its corresponding edge coordinate and finally to the single reference point for efficient detection and classification of bollard towards autonomous mooring is presented. At first stage, Mask R-CNN framework is trained with custom built bollard. The model obtained from the training is inferred with real data resulting in instance segment of bollard. The segmented mask obtained contains relatively large amount of…
The positioning system of the ANTARES Neutrino Telescope
2012
The ANTARES neutrino telescope, located 40km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning sys…
Switching Behaviour in Smart Phone Messaging Services : It’s a Question of Context, Content, and Features of the Service
2021
This paper studies switching behaviour in smart phone messaging services. This study aims to add knowledge about the factors affecting switching behaviour in smart phone messaging services. The empirical study is qualitative, and the data was collected with interviews using the laddering method. This study was carried out to find out the reasons behind customer decisions when choosing between smart phone messaging services. Using the Push-Pull Mooring framework, the findings of this study indicate that the switching decision regarding smart phone messaging service is influenced by three factors: the context of the message, the content of the message, and the features of the service.
The detrimental consequences for seagrass of ineffective marine park management related to boat anchoring.
2014
Posidonia oceanica (L.) Delile meadows are recognized as priority habitat for conservation by the EU Habitats Directive. The La Maddalena Archipelago National Park (Mediterranean Sea) P. oceanica meadow. , the dominant coastal habitat of the area, is mostly threatened by boat anchoring. 12. years after the establishment of mooring fields and anchoring restrictions, a study was conducted to measure their effectiveness on the conservation of seagrass and the mitigation of anchoring damage. We found that: (i) the condition of P. oceanica was disturbed, both in the mooring fields and in control locations; (ii) mooring fields and anchoring restrictions did not show to be an efficient system for …
Prediction of dynamic mooring responses of a floating wind turbine using an artificial neural network
2021
Abstract Numerical simulations in coupled aero-hydro-servo-elastic codes are known to be a challenge for design and analysis of offshore wind turbine systems because of the large number of design load cases involved in checking the ultimate and fatigue limit states. To alleviate the simulation burden, machine learning methods can be useful. This article investigates the effect of machine learning methods on predicting the mooring line tension of a spar floating wind turbine. The OC3 Hywind wind turbine with a spar-buoy foundation and three mooring lines is selected and simulated with SIMA. A total of 32 sea states with irregular waves are considered. Artificial neural works with different c…
Modeling of a Shared Mooring System for a Dual-Spar Configuration
2020
Abstract As floating wind turbines become more technically mature, the development of floating wind farms is under way. Cost-effective solutions are desired to reduce the mooring costs. The concept of a shared mooring system has been proposed for this purpose. This work presents a method to model the shared mooring system for a dual-spar configuration. By applying the theory in elastic catenary of cable structures, a shared line can be modelled. To verify the method, a dual-spar system is modelled in a multibody simulation tool, in which two floating wind turbines are connected via a shared line. Static analyses are performed by using the present method and the simulation tool. Further, a s…
A comparative study on the dynamic response of three semisubmersible floating offshore wind turbines
2019
Abstract Currently, there is a great interest to globally develop offshore wind energy due to the greenhouse effect and energy crisis. Great efforts have been devoted to develop reliable floating offshore wind energy technology to exploit the wind energy resources in deep seas. This paper presents a comparative study of the dynamic response of three different semisubmersible floating wind turbine structures. All the three platforms support the same 5MW wind turbine. The platforms examined are: a V-shaped Semi, an OC4-DeepCwind Semi and a Braceless Semi at 200 m water depth. A dynamic analysis is carried out in order to calculate and compare the performance of these platforms. The comparison…
Camera-LiDAR Data Fusion for Autonomous Mooring Operation
2020
Author's accepted manuscript. © 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. The use of camera and LiDAR sensors to sense the environment has gained increasing popularity in robotics. Individual sensors, such as cameras and LiDARs, fail to meet the growing challenges in complex autonomous systems. One such scenario is autonomous mooring, where the ship has to …
IT-tuotteiden ja -palveluiden vaihtaminen : musiikin suoratoistopalvelut
2016
Erilaisten sovellusten ja palveluiden käyttö kasvaa jatkuvasti. Palveluiden kysynnän kasvaessa on syntynyt toistensa kanssa kilpailevia palveluita, joilla käyttäjät katsovat esimerkiksi videoita ja kuuntelevat musiikkia erilaisten laitteiden välityksellä. IT-tuotteiden ja -palveluiden vaihtaminen nouseekin mie-lenkiintoiseksi tutkimuksen aiheeksi. Tällä saadaan selvitettyä miten eri palveluita ja tuotteita käytetään, sekä mitkä tekijät vaikuttavat näiden välillä vaihtamiseen. Näillä tiedoilla on merkitystä niin käyttäjän, kuin palveluntarjoajankin kannalta. Vaihtamistutkimuksen avulla saadaan tehtyä palveluista paremmin käyttäjien toiveita vastaavia, sekä havaittua vaihtamiseen vaikuttavia …