Costantini J.-M.,CDEX |
Fasoli M.,University of Milan Bicocca |
Beuneu F.,Ecole Polytechnique - Palaiseau |
Boizot B.,Ecole Polytechnique - Palaiseau
Philosophical Magazine | Year: 2014
Yttria-stabilized zirconia (YSZ) single crystals (for 9.5 and 18 mol% yttria) were irradiated at room temperature (RT) by X-rays (W white spectrum) and 2.5-MeV electrons. The growth curves of the so-called T-centre (for trigonal centre, i.e. Zr3+ sitting in a trigonal symmetry site) were studied as a function of absorbed dose, or irradiation time, by UV-visible optical absorption (OA) spectroscopy and X-band electron paramagnetic resonance spectroscopy. The defect concentration at saturation and the production rate are increased by a factor around two for 18 mol% yttria with respect to 9.5 mol%. Defect decay was then followed after irradiation by OA spectroscopy as a function of ageing time at RT. Growth and decay curves of the T-centre are modelled on the basis of rate equations of charge-exchange reactions with the zirconium lattice ions. Increase in yttrium content is thought to decrease hole trapping on Zr3+ ions, thereby enhancing T-centre formation. © 2014 Taylor & Francis.
Inoue T.,CDEX |
Shiosawa T.,Kawasaki Heavy Industries |
Takagi K.,University of Tokyo
IEEE Journal of Oceanic Engineering | Year: 2013
A crawler system has the potential to expand research and development on seafloors with irregular steep terrain and sand. Characteristic parameters in water, such as added mass, buoyancy, and hydrodynamic forces, considerably affect and decrease the mobility of crawler-type remotely operated vehicles (ROVs). To study and evaluate the mobile performance of a crawler system, it is important to investigate the dynamic motion of the crawler system by considering these effects. This paper presents a mathematical model of an underwater crawler system to show the dynamic effects on the vehicle's motion; experiments were conducted on a crawler-type ROV climbing over a bump in a water tank to examine the slip characteristics at sea. The simulated results agreed well with the experimental results. The mathematical model presented in this paper simulates the dynamic motion for climbing over a bump and the slip characteristics very well, and it reveals the physics of the crawler-type ROV's motion. The proposed mathematical model is useful for dynamic analysis. © 1976-2012 IEEE.
Inagaki F.,Japan Agency for Marine - Earth Science and Technology |
Hinrichs K.-U.,University of Bremen |
Scientific Drilling | Year: 2016
The Integrated Ocean Drilling Program (IODP) Expedition 337 was the first expedition dedicated to subseafloor microbiology that used riser-drilling technology with the drilling vessel Chikyu. The drilling Site C0020 is located in a forearc basin formed by the subduction of the Pacific Plate off the Shimokita Peninsula, Japan, at a water depth of 1180 m. Primary scientific objectives during Expedition 337 were to study the relationship between the deep microbial biosphere and a series of ~2 km deep subseafloor coalbeds and to explore the limits of life in the deepest horizons ever probed by scientific ocean drilling. To address these scientific objectives, we penetrated a 2.466 km deep sedimentary sequence with a series of lignite layers buried around 2 km below the seafloor. The cored sediments, as well as cuttings and logging data, showed a record of dynamically changing depositional environments in the former forearc basin off the Shimokita Peninsula during the late Oligocene and Miocene, ranging from warm-temperate coastal backswamps to a cool water continental shelf. The occurrence of small microbial populations and their methanogenic activity were confirmed down to the bottom of the hole by microbiological and biogeochemical analyses. The factors controlling the size and viability of ultra-deep microbial communities in those warm sedimentary habitats could be the increase in demand of energy and water expended on the enzymatic repair of biomolecules as a function of the burial depth. Expedition 337 provided a test ground for the use of riser-drilling technology to address geobiological and biogeochemical objectives and was therefore a crucial step toward the next phase of deep scientific ocean drilling. © 2016 Author(s).
Strasser M.,ETH Zurich |
Henry P.,College de France |
Kanamatsu T.,Japan Agency for Marine - Earth Science and Technology |
Thu M.K.,CDEX |
Moore G.F.,University of Hawaii at Manoa
Submarine Mass Movements and Their Consequences - 5th International Symposium | Year: 2012
Integrated Ocean Drilling Program (IODP) Expedition 333 drilled and cored a Pleistocene- To-Holocene succession of a slope-basin in the Nankai accretionary wedge, offshore southwest Japan. The slope-basin represents the depocentre for downslope sediment transport and comprises several mass- Transport deposits (MTDs), including an up to 180 m thick MTD. The recovered section (0-315 m below seafloor) records ∼ 1 Million years of submarine landsliding history in this active tectonic setting. We present D/V Chikyu shipboard results from Site C0018, including litho- bio- magneto- And tephra-stratigraphy and physical properties data. Six MTDs of thickness ranging from 0.5 to 61 m were identified from visual core description and X-ray CT-scans. The thickest MTD is also the oldest (emplaced between 0.85 and 1.05 Ma) and it coincides with a lithological transition between a sandy turbidite sequence below, and ash-bearing hemipelagites comprising several MTDs above. The deformation style within the MTD is heterogeneous: intervals of disturbed sediments are interbedded within intervals inferred to retain original, coherent bedding. In three occurrences the base of the MTD is defined by a shear zone within fine-grained sediments. These observations suggest that slumping and mass- Transport is dominated by localized plastic deformation. Furthermore, mass movements are an active process that is shaping the present-day seafloor, as evidenced by numerous surficial slump scars and the occurrence of a shallowly buried, presumably Holocene MTD at Site C0018. © Springer Science+Business Media B.V. 2012.
Cdex | Date: 2012-09-14
A handheld or portable detection system with a high degree of specificity and accuracy, capable of use at small and substantial standoff distances (e.g., greater than 12 inches) is utilized to identify specific substances and mixtures thereof in order to provide information to officials for identification purposes and assists in determinations related to the legality, hazardous nature and/or disposition decision of such substance(s). The system uses a synchronous detector and visible light filter to enhance detection capabilities.