Search Results (970)

Inspection, maintenance, and repair (IMR) operations on underwater infrastructure remain costly and time-intensive because fully teleoperated remote operated vehicle s(ROVs) lack the range and dexterity necessary for precise cooperative underwater manipulation, and the alternative of using professional divers is ruled out due to the risk involved. This work presents and experimentally validates an autonomous, dual-I-AUV (Intervention–Autonomous Underwater Vehicle) system capable of assembling rigid pipeline segments through coordinated actions in a confined underwater workspace. The first I-AUV is a Girona 500 (4-DoF vehicle motion, pitch and roll stable) fitted with multiple payload cameras and a 6-DoF Reach Bravo 7 arm, giving the vehicle 10 total DoF. The second I-AUV is a BlueROV2 Heavy equipped with a Reach Alpha 5 arm, likewise yielding 10 DoF. The workflow comprises (i) detection and grasping of a coupler pipe section, (ii) synchronized teleoperation to an assembly start pose, and (iii) assembly using a kinematic controller that exploits the Girona 500’s full 10 DoF, while the BlueROV2 holds position and orientation to stabilize the workspace. Validation took place in a 12 m × 8 m × 5 m water tank. Results show that the paired I-AUVs can autonomously perform precision pipeline assembly in real water conditions, representing a significant step toward fully automated subsea construction and maintenance. Full article

Here, we report the discovery of silica- and sulfur-enriched deposits forming on the seafloor off Zannone Island (western Mediterranean Sea), where hydrothermal activity is ongoing. Our multidisciplinary investigation reveals that these deposits form through the interplay between hydrothermal processes and microbial activity. The deposits result from a dynamic equilibrium involving microbial mediation, sedimentation, and episodic lithification, driven primarily by two mineralization pathways: silica and sulfur precipitation. This study provides new insights into the bio-sedimentary processes shaping authigenic crusts in shallow submarine hydrothermal settings, contributing to a broader understanding of mineralization in marine environments influenced by both geological and biological factors. Full article

The polyvalent nature of water is one often explored in fiction by Caribbean writers, and this paper will consider the ways that the representations of mermaids act as an extension of this exploration. Mermaids are central to a number of folk traditions across the Caribbean region and its diaspora. On islands, including Trinidad, Martinique, Carriacou, and Haiti, with names such as Fairymaid, Mama Glo, and La Siren, mermaids are often regarded as mothers and protectresses of both the sea and the creatures within it. This paper will analyse the representation of the mermaid in Monique Roffey’s The Mermaid of Black Conch (2020) and consider how the novel utilises the mermaid and an aquatic poetics to explore Kamau Brathwaite’s conceptualisation of a submarine unity for the Caribbean. Full article

Active continental margins, generally characterized by narrow shelves incised by canyons, are pervasively shaped by submarine landslides that can occur near coastal areas. In this context, creating landslide susceptibility maps is the first step in landslide geohazard assessment. This paper focuses on shallow-water submarine landslides along the Capo d’Orlando continental margin and presents a related susceptibility map using the Weight of Evidence method. This method quantifies the strength of the association between a landslide inventory and predisposing factors. A geomorphological analysis of the continental shelf and upper slope yielded a landslide inventory of 450 initiation points, which were combined with five specifically selected preconditioning factors. The results revealed that the most favourable conditions for shallow-water landslides include slopes between 5° and 15°, proximity to faults (<1 km), proximity to river mouths (<2 km), the presence of consolidated lithologies and sandy terraces, and slopes facing NE and E. The landslide susceptibility map indicates that susceptible areas are in canyon heads and flanks, as well as in undisturbed slope portions near canyon heads where retrogressive landslides are likely. The model results are robust (AUC = 0.88), demonstrating that this method can be effectively applied in areas with limited geological data for preliminary susceptibility assessments. Full article

This study presents a comprehensive case analysis of pyrite-hosted solid inclusions and their metallogenic significance in the Bainaimiao porphyry Cu deposit in NE China, which is genetically linked to the early Silurian granodiorite intrusion and porphyry dykes. Solid inclusions in pyrite from the deposit’s southern ore belt were analyzed across distinct mineralization stages. Using Electron Probe Micro-Analysis (EPMA) and in situ sulfur isotope analysis (MC-ICP-MS), inclusion assemblages in pyrite were identified, including pyrrhotite-chalcopyrite solid solutions, biotite, and dolomite. The results demonstrate that these inclusions primarily formed through coprecipitation with pyrite during crystal growth. Early-stage mineralizing fluids exhibited extreme temperatures exceeding 700 °C, coupled with low oxygen fugacity (fO₂) and low sulfur fugacity (fS₂). Sulfur isotope compositions (δ³⁴S: −5.85 to −4.97‰) indicate a dominant mantle-derived magmatic sulfur source, with contributions from reduced sulfur in sedimentary rocks. Combined with regional geological evolution, the Bainaimiao deposit is classified as a porphyry-type deposit. Its ore-forming materials were partially derived from Mesoproterozoic submarine volcanic exhalative sedimentary source beds, which were later modified and enriched by granodiorite porphyry magmatism. Full article

The South Shetland Islands and Antarctic Peninsula (SHETPENANT region) constitute a geodynamically active area shaped by the interaction of major tectonic plates and active magmatic systems. This study analyzes GNSS time series spanning from 2017 to 2024 to investigate surface deformation associated with the 2020–2021 seismic swarm near the Orca submarine volcano. Horizontal and vertical displacement velocities were estimated for the preseismic, coseismic, and postseismic phases using the CATS method. Results reveal significant coseismic displacements exceeding 20 mm in the horizontal components near Orca, associated with rapid magmatic pressure release and dike intrusion. Postseismic velocities indicate continued, though slower, deformation attributed to crustal relaxation. Stations located near the Orca exhibit nonlinear, transient behavior, whereas more distant stations display stable, linear trends, highlighting the spatial heterogeneity of crustal deformation. Stress and strain fields derived from the velocity models identify zones of extensional dilatation in the central Bransfield Basin and localized compression near magmatic intrusions. Maximum strain rates during the coseismic phase exceeded 200 $\mathrm{\nu }$strain/year, supporting a scenario of crustal thinning and fault reactivation. These patterns align with the known structural framework of the region. The integration of GNSS-based displacement and strain modeling proves essential for resolving active volcano-tectonic interactions. The findings enhance our understanding of back-arc deformation processes in polar regions and support the development of more effective geohazard monitoring strategies. Full article

In an effort to restrict further increases in climate change, governments and companies are exploring ways to reduce greenhouse gas (GHG) emissions. In this context, the oil industry, which contributes to indirect GHG emissions, is seeking ways to develop solutions to this issue. One such approach focuses on the connection of offshore oil production platforms to the onshore power grid via high-voltage direct current (HVDC), enabling a total or partial reduction in the number of local generators, which are generally powered by gas turbines. Therefore, this work aims to determine the technical feasibility, based on transient and dynamic stability analyses, of electrifying a system composed of six floating production storage and offloading (FPSO) units connected to a hub, which is powered by the onshore grid through submarine cables using HVDC technology. The analysis includes significant contingencies that could lead the system to undesirable operating conditions, allowing for the identification of appropriate remedial control actions. The analysis, based on real data and parameters, was carried out using PSCAD software. The results show that the modeled system is technically viable and could be adopted by oil companies. In addition to aligning with global warming mitigation goals, the proposal includes a complex system modeling approach, with the aim of enabling further study. Full article

Green hydrogen is a promising solution for decarbonizing emission-intensive sectors, with its production through offshore wind energy offering viable opportunities. This study presents a preliminary assessment of the main environmental factors potentially affected by offshore wind and green hydrogen projects in Uruguay’s Exclusive Economic Zone (EEZ), where such developments pose environmental challenges that require evaluation, particularly given the limited prior research in Uruguay and Latin America. Through a comprehensive review of international literature and national technical data, the study identifies key interactions between project activities and the physical, biotic, and anthropic environmental components during the development, construction, and operational phases. Using cross-reference matrices and impact categorization, the analysis highlights that activities such as foundation installation, submarine cable deployment, and offshore electrolysis could significantly affect the seabed, underwater noise levels, water quality, and marine biodiversity. The biotic and physical environment were found to be the most frequently impacted. To contextualize these findings, technical information specific to Uruguay’s EEZ was reviewed to identify the most vulnerable regional environmental factors. The results offer a science-based foundation to support early-stage environmental assessments and guide sustainable offshore energy development in the region. Full article

The generalization of nautical charts remains crucial in geographic information science and cartography. Traditional geometry-based methods have contributed to the advancement of automated generalization to a certain extent, but they still exhibit significant limitations in handling complex marine spatial relationships. This paper proposes the Graph Neural Network (GNN) as a transformative solution. GNN excels at processing non-Euclidean geospatial data, addressing the following three critical problems in the generalization of submarine terrain data: geographic feature representation, data processing, and the generalization process. The review first systematically outlines the main operators and fundamental methods of chart generalization. It analyzes their specific performance in various elements such as soundings, depth contours, islands, and coastlines. Subsequently, the potential of GNN is explored in addressing the limitations of traditional generalization methods. Although GNN is not a panacea, it shows advantages through horizontal and vertical comparisons. Finally, the challenges encountered in applying GNN to cartographic generalization are discussed. Full article

The snake-laying method is widely employed as an effective strategy for global buckling mitigation in submarine pipelines. The uneven distribution of soil resistance along pipeline routes significantly amplifies the complexity of global buckling responses in snake-laid pipelines and challenges their control mechanisms. This study establishes a finite element computational model to investigate the effects of soil resistance distribution gradients and patterns along pipeline routes, alongside their coupling with critical snake-laying parameters (spacing, offset, curvature). The research revealed that an uneven distribution of soil resistance can induce the global buckling submersion phenomenon in snake-laid pipelines. Among the critical snake-laying parameters, curvature enhancement proves to be the most effective mitigation strategy against the global buckling submersion phenomenon. Additionally, an improvement in the conventional uniform-laying scheme is proposed for uneven soil resistance distribution: the originally planned snake-laid section can be replaced by a straight pipeline section in the high-resistance zone. This study provides enhanced technical solutions for global buckling prevention in pipelines traversing uneven seabeds. Full article

Geothermal energy is a low-carbon and reliable energy resource capable of generating both heat and electricity from the Earth’s internal thermal energy. While geothermal development has traditionally been focused on onshore sites, offshore geothermal resources are attracting growing interest due to advancements in technology, the search for alternative baseload power, and the opportunity to repurpose decommissioned petroleum infrastructure. Recent efforts include utilizing abandoned oil and gas fields to adapt existing infrastructure for geothermal use, as well as exploring high-temperature geothermal zones such as submarine volcanoes and hotspots. Despite these initiatives, research output, scientific publications and patents remain relatively limited, suggesting that offshore geothermal technology is still in its early stages. Countries like Italy, Indonesia and Turkey are actively investigating geothermal resources in volcanic marine areas, while North Sea countries and the USA are assessing the feasibility of converting mature oil and gas fields into geothermal energy sites. These diverse strategies underscore the regional geological and infrastructure conditions in shaping development approaches. Although expertise from the oil and gas industry can accelerate technological progress in marine geothermal energy, economic challenges remain. Therefore, improving cost competitiveness is crucial for offshore geothermal energy. Full article

Power output and economic cost are two critical factors influencing the layout of tidal stream turbine arrays. To identify the optimal configuration, this study establishes a two-objective optimization framework that simultaneously considers these factors. Both the spatial location and yaw angle of each turbine are optimized to enhance overall power output, while the total length of submarine cables, which is used to transmit electricity from the turbines to the onshore power station, is adopted as the metric for economic cost. The Huludao water area is selected as the study domain. A 12-turbine array is examined under varying weight coefficients to investigate the trade-off between maximizing power output and minimizing economic cost. The optimization results show that submarine cable length decreases linearly as its economic weight coefficient increases, while the array’s power output exhibits a stepwise decline. This indicates that, with carefully chosen weight coefficients, economic costs can be significantly reduced without a proportional sacrifice in power output. Furthermore, increasing the number of turbines connected by a single cable not only enhances power output but also reduces total cable length, thereby improving the overall profitability of the optimized array layout. Full article

The status of an optic–electric composite high-voltage submarine cable (referred to as submarine cable) can be monitored based on optical fiber-distributed sensing technology, and at the same time, no additional sensor is needed in the monitoring system. Currently, this technology is widely used in submarine cable monitoring systems. To estimate the temperatures of conductor and XLPE (cross-linked polyethylene) insulation of the submarine cable based on the ambient temperature and optical fiber temperature, the thermoelectric coupling field model of the 110 kV single-core submarine cable is established and validated. The thermoelectric coupling field models of the submarine cable with different values of ambient temperature and ampacity are built, and the influence of ambient temperature and ampacity on the temperatures of conductor, insulation and optical fiber is investigated. Furthermore, the relationship between the temperatures of the conductor and insulation and the ambient temperature and optical fiber temperature is obtained. Then, estimation formulas for temperatures of conductor and insulation of submarine cable according to ambient temperature and optical fiber temperature are obtained and preliminarily validated. This work lays the foundation for condition evaluation of the submarine cable insulation, life expectancy and maximum allowable ampacity estimation. Full article

Membrane technologies are used in the production of potable water and the treatment of wastewater in the military forces, providing the highest level of contaminant removal at an energy-efficient cost. This review examines the integration and application of membrane technologies, including reverse osmosis, nanofiltration, ultrafiltration, electrodialysis and advanced hybrid systems, in the treatment of wastewater generated at military bases, naval vessels and submarines. Special emphasis is placed on purification technologies for chemically, biologically and radiologically contaminated wastewater, as well as on the recycling and treatment of wastewater streams by mobile systems used in military applications. Given the specific requirements of complex military infrastructures, particularly in terms of energy efficiency, unit self-sufficiency and reduced dependence on logistical supply chains, this work analyses the latest advances in membrane technologies. Innovations such as nanographene membranes, biomimetic membranes, antifouling membrane systems and hybrid configurations of forward osmosis/reverse osmosis and electrodialysis/reverse electrodialysis offer unique potential for implementation in modular and mobile water treatment systems. In addition, the integration and operational use of these advanced technologies serve as a foundation for the development of autonomous military water supply strategies tailored to extreme operational conditions. The continued advancement and optimization of membrane technologies in military contexts is expected to significantly impact operational sustainability while minimizing environmental impact. Full article

The present work proposes a novel fractional-order multifunction filter topology in current-mode (CM), which is designed based on the Modified Current Feedback Operational Amplifier (MCFOA). The proposed design simultaneously generates fractional-order low-pass (FO-LPF), high-pass (FO-HPF), and band-pass (FO-BPF) outputs while utilizing an optimized set of essential active and passive elements, thereby ensuring simplicity, cost efficiency, and compatibility with integrated circuits (ICs). The fractional-order feature allows precise control over the transition slope between the passband and the stopband, enhancing design flexibility. PSpice simulations validated the filter’s theoretical performance, confirming a 1 kHz cut-off frequency, making it suitable for VLF applications such as military communication and submarine navigation. Monte Carlo analyses demonstrate robustness against parameter variations, while a low THD, a wide dynamic range, and low power consumption highlight its efficiency for high-precision, low-power applications. This work offers a practical and adaptable approach to fractional-order circuit design, with significant potential in communication, control, and biomedical systems. Full article