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| Registros recuperados: 11 | |
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| Bivaud, J. |
| At present, offshore placers are generally exploited by means of traditional dredging equipment. This technique, called the "vertical method," consists of working the seabed directly from the surface support vessel through a rigid upflow pipe equipped, when necessary, with a sediment preloosening system. In contrast with the vertical method, this approach is based on the principle of working along the seabed with transfer of spoil up to the surface after extraction. We therefore call this the "horizontal method." Although it varies according to sites, in most cases this method comprises the design of a vehicle, self-propelled to some degree, which moves along the seafloor, carries and operates the appropriate mining tools and includes a system to transfer... |
| Tipo: Text |
Palavras-chave: Offshore operations; Marine technology; Unmanned vehicles; Mining vessels; Placers; Deep sea mining. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1168.pdf |
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| Daste, S. |
| The "CRABE" method is a crack detection technique based on the use of low electromagnetic frequencies. This (patented) method relies on a global injection of current within the structure under inspection. The presence of a crack shall cause a disruption in the current flow, and consequently of the magnetic field off the surface in the vicinity of a defect. It is this magnetic signature which is detected by the magnetic sensor used with "CRABE". The major advantage of this process, developed by TRAVOCEAN and the LETI Division of CEA with the help of IFREMER, appears clearly: No preliminary cleaning of the welds to be inspected is required, since no contact is necessary. Similarly, it shall be possible to inspect the whole of structures to a total cost all... |
| Tipo: Text |
Palavras-chave: Offshore structures; Fouling; Underwater exploration; Steel structures; Sensors; Cracks; Detection; Unmanned vehicles; Marine technology. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1161.pdf |
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| Alayse, Anne-marie. |
| With the advent of deep submergence research vessels (DSRVs) biological and ecological studies of ocean deeps have made great strides. Especially these submersibles allowed to conduct physiological and biochemical experiments on benthic fauna directly on the bottom or on board with alive retrieved animals. A second great interest is the possibility to work in chaotic areas and on microenvironments. Without DSRVs most of measurements and observations obtained on hydrothermals vents would had been impossible. We will present the different equipment designed for the two French DSRVs used during the cruises conducted by the Departement "Environnement Profond" de l'IFREMER to study hydrothermal and "normal" deep-sea ecosystems. We will discuss the new devices... |
| Tipo: Text |
Palavras-chave: Oceanography; Hydrothermal springs; Ecosystems; Abyssal zone; Cruises; Ecology; Biology; Deep water; Unmanned vehicles; Manned vehicles. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1146.pdf |
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| Otsuka, K. |
| The JAMSTEC/Deep Tow Camera System conducts pre-site-surveys for the manned submersible "SHINKAI 2000". The vehicle is towed by double armored coaxial cable (RG-8/U) of 4500 m length. The color composite video signal is converted to an FM signal with central frequency of 6.15 MHz because it is very difficult to compensate completely for the transmission loss of video frequency through the coaxial cable. The data from the CTD sensors and the altimeter are displayed with date and time on the monitor screen in real time. Temperature data has proved very important in finding hydrothermal anomaly phenomena. Two years ago, our research group found an active chimney at North Fiji Basin during cooperative cruise between France and Japan. Last year, we deployed... |
| Tipo: Text |
Palavras-chave: Altimeters; Sensors; Television systems; Underwater cameras; Ocean floor; Unmanned vehicles. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1153.pdf |
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| Duncan, N. |
| Pressures of economics are driving the ROV industry to develop NDT equipment which will allow the ROV to detect, and assess, the presence of fatigue induced surface breaking defects in nodal welds and their associated heat affected zones. Two main techniques of NDT are currently being developed by Comex to provide ROV services to meet client needs. One is an MPI system and the other an Eddy Current system. Both are derivatives of equipment currently being used successfully by divers in the North Sea. The two systems are complementary to each other rather than in competition and offer a high degree of defect evaluation. This paper will discuss the requirements placed on the tool deployment system by the task, the worksite, the ROV characteristics and the... |
| Tipo: Text |
Palavras-chave: Nondestructive testing; Manipulators; Marine technology; Unmanned vehicles. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1160.pdf |
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| Savoye, Bruno. |
| Sediment instability appears to be important as a part of global sedimentary budget. Among the various types of sedimentary instabilities, submarine slides are probably the most spectacular and the hardest to study and predict, although their consequences on human and industrial marine activities can be dramatic. IFREMER is conducting a research project on this topic. An area off Nice (France) has been particularly studied because of its recent activity. Mapping and instability area detection have been carried out. With the possibility of direct interactive observation and highly accurate submarine in -situ operation, the submersible is an extremely efficient tool for sediment studies, but diving purposes have to be precisely defined to provide useful... |
| Tipo: Text |
Palavras-chave: Sediments; Instability; Sedimentology; Sedimentary structures; Ocean floor; Marine technology; Geology; Submersibles; Unmanned vehicles. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1150.pdf |
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| Dupin, G. |
| The development of telecommunications and in particular the constantly increasing demand of digital services make the submarine telecommunication cables very strategic and the users of these services very sensitive to interruptions or degraded quality. Then, the main cause of faults on submarine telecommunication cables is trawler or anchor damage. Therefore, once the route has been finalized, only a good quality of burial can reduce the risks linked to these external aggressions. The tools used to-day by France Telecom for burial are: a standard sea-plough, with a share, towed by the cableship simultaneously to the laying operation; ROVs (SCARAB) to post-lay bury cables by jetting, repair buried cables and rebury the cable after repair. |
| Tipo: Text |
Palavras-chave: Surveillance and enforcement; Anchors; Communication systems; Working underwater; Burying; Submarine cables; Unmanned vehicles. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1167.pdf |
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| Rougier, R. |
| Installation and tie-in using tig automatic hyperbaric welding of 3 expansion loops to the Gullfaks "C" gravity base platform at 220 meters in the Norwegian sector of the North Sea. Operation performed from a dynamically positioned diving support vessel using divers and construction ROV during the summer 1989. Facing the technological challenge created by the deep diving aspects, the technical difficulties of doing welding operation at this depth, and the tight commercial constraints, a review of the tasks was conducted to optimize and reduce the offshore time, leading to innovations in the procedures selected to perform the work: Use of a working ROV, assisted by an observation vehicle, to carry out subsea tasks traditionally reserved for construction... |
| Tipo: Text |
Palavras-chave: Diving; Offshore structures; Robots; Divers; Welding underwater; Offshore engineering; Unmanned vehicles; Marine technology; Offshore. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1162.pdf |
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| Registros recuperados: 11 | |
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