Faculty of Science and Engineering
https://pearl.plymouth.ac.uk/handle/10026.1/11750
2024-03-28T04:05:40ZDynamic Accretion Beneath a Slow‐Spreading Ridge Segment: IODP Hole 1473A and the Atlantis Bank Oceanic Core Complex
https://pearl.plymouth.ac.uk/handle/10026.1/22218
Dynamic Accretion Beneath a Slow‐Spreading Ridge Segment: IODP Hole 1473A and the Atlantis Bank Oceanic Core Complex
Dick, HJB; MacLeod, CJ; Blum, P; Abe, N; Blackman, DK; Bowles, JA; Cheadle, MJ; Cho, K; Ciazela, J; Deans, JR; Edgcomb, VP; Ferrando, C; France, L; Ghosh, B; Ildefonse, B; John, B; Kendrick, MA; Koepke, J; Leong, JAM; Liu, C; Ma, Q; Morishita, T; Morris, A; Natland, JH; Nozaka, T; Pluemper, O; Sanfilippo, A; Sylvan, JB; Tivey, MA; Tribuzio, R; Viegas, G
809 deep IODP Hole U1473A at Atlantis Bank, SWIR, is 2.2 km from 1,508-m Hole 735B and 1.4 from 158-m Hole 1105A. With mapping, it provides the first 3-D view of the upper levels of a 660-km2 lower crustal batholith. It is laterally and vertically zoned, representing a complex interplay of cyclic intrusion, and ongoing deformation, with kilometer-scale upward and lateral migration of interstial melt. Transform wall dives over the gabbro-peridotite contact found only evolved gabbro intruded directly into the mantle near the transform. There was no high-level melt lens, rather the gabbros crystallized at depth, and then emplaced into the zone of diking by diapiric rise of a crystal mush followed by crystal-plastic deformation and faulting. The residues to mass balance the crust to a parent melt composition lie at depth below the center of the massif—likely near the crust-mantle boundary. Thus, basalts erupted to the seafloor from >1,550 mbsf. By contrast, the Mid-Atlantic Ridge lower crust drilled at 23°N and at Atlantis Massif experienced little high-temperature deformation and limited late-stage melt transport. They contain primitive cumulates and represent direct intrusion, storage, and crystallization of parental MORB in thinner crust below the dike-gabbro transition. The strong asymmetric spreading of the SWIR to the south was due to fault capture, with the northern rift valley wall faults cutoff by a detachment fault that extended across most of the zone of intrusion. This caused rapid migration of the plate boundary to the north, while the large majority of the lower crust to spread south unroofing Atlantis Bank and uplifting it into the rift mountains.
2019-12-01T00:00:00ZFuture of maritime autonomy: cybersecurity, trust and mariner's situational awareness
https://pearl.plymouth.ac.uk/handle/10026.1/22214
Future of maritime autonomy: cybersecurity, trust and mariner's situational awareness
Palbar Misas, JD; Hopcraft, R; Tam, K; Jones, K
As technology evolves, the level of automation in the maritime industry also grows. Given the extensive benefits they offer, the industry will continue to develop its digital capabilities in order to improve. One key example of this is the industry currently striving for fully autonomous vessels. Current crew-based maritime operations on board rely on a mixture of automated simplistic processes, human decision-making, and human interventions. The future autonomy suggests the removal of the mariner physically on board. The remote nature of these operations will subject mariners and vessels to new operational risks, such as a potential reduction in Situational Awareness (SA) and/or cyber threats. In this research, authors engaged with navigators with a range of traditional operational experiences to extend previous discussions conducted with cadets on the importance of SA in maritime operations, and the potential challenges facing this when engaging in remote operations. This was done using tabletops, questionnaires and full bridge simulator exercises. Through this engagement, authors found that future navigators will need training to be equipped with new skills to interact with digital systems during different modes of human operation (such as remote monitoring, supervision and intervention) to overcome perceived challenges including cyber incident management.
On the use of constrained focused waves for characteristic load prediction
https://pearl.plymouth.ac.uk/handle/10026.1/22209
On the use of constrained focused waves for characteristic load prediction
Tosdevin, T; Jin, S; Simmonds, D; Hann, M; Greaves, D
Physical experiments investigating the extreme responses of a semi-submersible floating offshore wind turbine were conducted to allow a comparison of design wave methods. A 1:70 scale model of the IEA 15MW reference turbine and VolturnUS-S platform was studied focusing on the hydrodynamics under parked turbine conditions. A comparison of characteristic load predictions was made between design standard recommendations by the IEC and DNV covering different design wave types and post processing methods. Constrained waves are permitted for predicting characteristic loads for fixed offshore turbines but the extent to which they are suitable for floating devices is questionable. A constrained wave method for characteristic load prediction is applied and it is concluded that in general characteristic responses related to pitch may be estimated well with single response conditioned focused waves but for response types where the low frequency surge is important, e.g. mooring loads, constrained focused waves need to be applied.
2022-10-03T00:00:00ZOn the Use of Response Conditioned Focused Wave and Wind Events for the Prediction of Design Loads
https://pearl.plymouth.ac.uk/handle/10026.1/22208
On the Use of Response Conditioned Focused Wave and Wind Events for the Prediction of Design Loads
Tosdevin, T; Edwards, E; Holcombe, A; Brown, S; Ransley, E; Hann, M; Greaves, D
<jats:title>Abstract</jats:title>
<jats:p>Reducing the time required to predict design loads and responses would result in significant efficiency improvements to the floating offshore wind turbine (FOWT) design process. Present methods of predicting design values require at least six, 1-hour sea condition simulations. It would therefore be highly beneficial to identify what conditions lead to the extremes of a range of responses of interest to reduce the length of the time series required. The results of physical, 1:70 scale model experiments using the UMaine VolturnUS-S platform and IEA 15MW reference wind turbine are presented. A Real-time hybrid testing approach, where wind loading is calculated via a surrogate model and reproduced by two on board fans is used to approximate the aerodynamic loads at model scale. The response spectra for several responses of interest are used to construct short wave and wind time series using a ‘conditional random response wave’ approach developed in ship design. These time series, the responses they produce, and their resulting design value estimates are compared to those from 1-hour-long, irregular wave, and turbulent wind time series. This comparison is conducted for operating conditions at rated wind speed corresponding to design load case (DLC) 1.6, and it is performed at a location in the Celtic Sea.</jats:p>
2023-12-18T00:00:00Z