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Components and structures working in the marine environment are exposed to high stresses attributable to the action of wind, waves, and tides. Moreover, they have to face hostile and severe environmental conditions during their lifetime, being placed in the splash zone if not even submerged in saltwater. The application of polymer composites in marine systems has been the focus of intensive studies in the last decades, highlighting potential benefits given by the replacement of several components, such as ship hulls, propeller blades, wind, and tidal turbine blades, to cite but a few. The present paper reports the latest advances in this area, addressing the applications of advanced composites in ships and ship components, offshore oil and gas composites, marine renewable energy and underwater repairing.

Yu, H.; Sun, H., and Chen, M., 2021. The evolution of industrial structure for marine economic growth in China: An empirical study on the effects of rationalization and optimization. Journal of Coastal Research, 37(5), 1042–1052. Coconut Creek (Florida), ISSN 0749-0208. Against the background of China's new normal economy, the adjustment of the marine industrial structure is still a key issue, but current research on the relationship between the marine industrial structure and marine economic growth has not reached a consistent conclusion. This paper measures the structure of the marine industry with two indicators of the rationalization and optimization of the industrial structure and constructs a fixed effects model to explore the effects of the marine industrial structure on marine economic growth and the mechanism using panel data of China's coastal provinces, cities, and districts from 1997 to 2016. The results show the following. (1) In the study period, the rationalization of the marine industrial structure promoted marine economic growth, whereas the optimization of the marine industrial structure restrained marine economic growth. (2) The mediation test shows that the rationalization of the marine industrial structure promotes the growth of the marine economy by improving the labor productivity of the marine industry, whereas the optimization of the marine industrial structure restrains the growth of the marine economy by curbing the productivity of the marine service industry. (3) After adding the moderator of government intervention into the model, it is found that the higher the degree of government intervention is, the more significant the promoting effect of the rationalization of the marine industrial structure on marine economic growth, and the negative effect of the optimization of the marine industrial structure on marine economic growth is significantly reduced.

Food webs as representations of who eats whom are at the core of community ecology. Incorporation of tools from network theory enables assessment of how complex systems respond to natural and human-induced stressors, revealing how harvesting may degrade the properties and resilience of food webs. We present a comprehensive, coastal marine food web that includes 147 taxa co-occurring on shallow subtidal reefs along the highly productive and exploited Humboldt Current System of central Chile. This food web has connectance of 0.06, link density of 1204 and mean chain length of 4.3. The fractions of intermediate (76%), omnivorous (49%) and cannibalistic (8%) nodes are slightly lower than those observed in other marine food webs. Of the 147 nodes, 34 are harvested. Links to harvested nodes represented 50 to 100% of all trophic links of non-harvested nodes, illustrating the great impact that fishery pressure can have on the food web. The food web was compartmentalized into 5 sub-webs with high representation of harvested taxa. This structure changes if the fishery node is removed. Similarity analyses identified groups of harvested species with non-harvested nodes, suggesting that these tropho-equivalents could be sentinel species for the community-wide impacts of coastal fisheries. We conclude that fishing effects can be transmitted throughout the food web, with no compartments completely unaffected by harvesting. It is urgent to establish monitoring programs for community-wide effects of fisheries and assess whether resilience of these highly productive subtidal food webs has already been compromised, thereby identifying essential nodes that require stronger fisheries regulation.

Sea ice loads on marine structures are caused by the failure process of ice against the structure. The failure process is affected by both the structure and the ice, thus is called ice-structure interaction. Many ice failure processes, including ice failure against inclined or vertical offshore structures, are composed of large numbers of discrete failure events which lead to the formation of piles of ice blocks. Such failure processes have been successfully studied by using the discrete element method (DEM). In addition, ice appears in nature often as discrete floes; either as single floes, ice floe fields or as parts of ridges. DEM has also been successfully applied to study the formation and deformation of these ice features, and the interactions of ships and structures with them. This paper gives a review of the use of DEM in studying ice-structure interaction, with emphasis on the lessons learned about the behaviour of sea ice as a discontinuous medium. This article is part of the theme issue 'Modelling of sea-ice phenomena'.

Diverse forms of offshore oil and gas structures are utilized for a wide range of purposes and in varying water depths. They are designed for unique environments and water depths around the world. The applications of these offshore structures require different activities for proper equipment selection, design of platform types, and drilling/production methods. This paper will provide a general overview of these operations as well as the platform classifications. In this paper, a comprehensive review is conducted on different offshore petroleum structures. This study examines the fundamentals of all types of offshore structures (fixed and floating), as well as the applications of these concepts for oil exploration and production. The study also presents various design parameters for state-of-the-art offshore platforms and achievements made in the industry. Finally, suitable types of offshore platforms for various water depths are offered for long-term operations. An extension of this study (Part II) covers sustainable design approaches and project management on these structures; this review helps designers in understanding existing offshore structures, and their uniqueness. Hence, the review also serves as a reference data source for designing new offshore platforms and related structures.

Real-time monitoring of large marine structures’ health, including drilling platforms, submarine pipelines, dams, and ship hulls, is greatly needed. Among the various kinds of monitoring methods, optical fiber sensors (OFS) have gained a lot of concerns and showed several distinct advantages, such as small size, high flexibility and durability, anti-electromagnetic interference, and high transmission rate. In this paper, three types of OFS used for marine structural health monitoring (SHM), including point sensing, quasi-distributed sensing, and distributed sensing, are reviewed. Emphases are given to the applicability of each type of the sensors by analyzing the operating principles and characteristics of the OFSs. The merits and demerits of different sensing schemes are discussed, as well as the challenges and future developments in OFSs for the marine SHM field.

Offshore platforms have had diverse applications in the marine industry, for example, oil or gas platforms can provide facilities to store the oil and gas before transport those to refineries. Offshore wind turbines are another well-known use of the offshore platform for generating power. As platforms encounter various strong forces from water and wind currents, the materials used for these structures are mainly steel or concrete. These platforms are classified into different types, according to the depth of water and their applications. In addition, offshore platforms, as artificial reefs may be used for decades at different marine conditions. Consequently, their design and maintenance are very important, otherwise, they can cause irreparable damage to the environment. This paper presents the latest and most significant design and monitoring methods, such as the optimal probabilistic seismic demand model, multi-objective optimization, dynamic response assessment, robust fault-tolerant control, etc., under different environmental and geographical conditions. Moreover, the effective factors on the life and failure of these offshore structures are comprehensively introduced to enhance awareness of them, which can be very helpful to improve the design and construction of more reliable and durable structures.

This paper delves into the application of digital twin monitoring techniques for enhancing offshore floating wind turbine performance, with a detailed case study that uses open-source digital twin software. We explore the practical implementation of digital twins and their efficacy in optimizing operations and predictive maintenance, focusing on controlling the real-time structural state of composite wind turbine structures and forecasting the remaining useful life by tracking the fatigue state in the structure. Our findings emphasize digital twins’ potential as a valuable tool for renewable energy, driving efficiency and sustainability in offshore floating wind installations. These aspects, along with the aforementioned simulations, whether in real-time or forecasted, reduce costly and unnecessary inspections and scheduled maintenance.

Friction stir welding (FSW) has been recognized as a revolutionary welding process for marine applications, effectively tackling the distinctive problems posed by maritime settings. This review paper offers a comprehensive examination of the current advancements in FSW design, specifically within the marine industry. This paper provides an overview of the essential principles of FSW and its design, emphasizing its comparative advantages when compared with conventional welding techniques. The literature review reveals successful implementations in the field of shipbuilding and offshore constructions, highlighting design factors as notable enhancements in joint strength, resistance to corrosion, and fatigue performance. This study examines the progress made in the field of FSW equipment and procedures, with a specific focus on their application in naval construction. Additionally, it investigates the factors to be considered when selecting materials and ensuring their compatibility in this context. The analysis of microstructural and mechanical features of FSW joints is conducted, with a particular focus on examining the impact of welding settings. The study additionally explores techniques for mitigating corrosion and safeguarding surfaces in marine environments. The study also provides a forward-looking perspective by proposing potential areas of future research and highlighting the issues that may arise in the field of FSW for maritime engineering. The significance of incorporating environmental and economic considerations in the implementation of FSW for extensive marine projects is emphasized.

Offshore solar emergence is driven by a lack of available land and the immense decarbonisation targets. It is a promising area of solar photovoltaic application, with multiple benefits when co-located with offshore wind, and with almost unlimited potential for nations living close to the sea. Research to understand the environmental implications of offshore solar must be carried out in parallel with the realization of the first pilot demonstrations. Such pilots provide important opportunities to learn to collect field data that can be used to verify untested assumptions about possible negative and positive impacts on the marine ecosystem and serve as input data for models that can forecast the effects of much larger-scale offshore solar. This paper reports on (1) the monitoring methods and first results of water quality parameters collected underneath a small (50 kWp and 400 m2) floating solar farm and at a reference location in the open sea; (2) observations of birds on top of the floating solar platforms and (3) biogeochemistry characteristics of the seabed around the solar farm. Both the water quality and the seabed characteristics studied here did not show a clear trend or deviation from normal conditions. The observations of birds on the floating platform were first-of-its-kind; no comparison is made to other floating infrastructure or other locations. Useful insights were gathered with respect to monitoring approaches around floating solar structures in high wave conditions.