Ocean Engineering, Renewable Energy, Sustainability and the Environment
24
Scopus Publications
Scopus Publications
Environmental Contour Methods for Long-Term Extreme Response Prediction of Offshore Wind Turbines Jixiang Zhang, Shan Wang, Milad Shadman, Mojtaba Maali Amiri, Baiqiao Chen, Chen An, Segen Farid Estefen Journal of Marine Science and Application, 2026 The long-term responses of offshore wind turbines (OWTs) are critical in the design phase, where precise assessments ensure structural reliability and operational efficiency. The environmental contour method (ECM) enables efficient analysis of design responses by focusing on a selected set of critical environmental conditions that predominantly drive long-term extreme responses. Despite its extensive use in offshore engineering, ECM’s application in the structural design and strength assessment of OWTs remains underexplored. This study offers a comprehensive overview of the utilization of ECM in the context of OWT design, incorporating a bibliometric analysis of publications from the Web of Science to identify research trends and key topics. The analysis highlights diverse approaches for estimating long-term extreme responses and constructing environmental contours using statistical distributions. Additionally, the study explores the application of ECM and its modified versions in the design and strength assessment of OWTs. Challenges and opportunities associated with ECM implementation in OWTs are critically analyzed, providing insights into ECM’s potential for enhancing the efficiency and reliability of OWT structural design.
STRUCTURAL INTEGRITY OF A REINFORCED CONCRETE SEMI-SUBMERSIBLE PLATFORM FOR A 15 MW FLOATING OFFSHORE WIND TURBINE John H. Chujutalli, Mojtaba Maali Amiri, Milad Shadman, Segen Farid Estefen Proceedings of ASME 2025 6th International Offshore Wind Technical Conference Iowtc 2025, 2025 There is a growing trend in the use of higher-power Offshore Wind Turbines (OWT), installed at significant distances from the coast and in deep waters, with the objective of increasing clean energy production and reducing costs. These floating structures, usually made of steel, are subjected to significant loads due to wind, waves, and their own weight. However, due to the high costs of construction, transportation, maintenance, and service life, reinforced concrete is being studied as a viable alternative for this type of structure. This study presents a reinforced concrete semi-submersible platform designed to support a 15 MW wind turbine. The proposed platform offers several advantages over existing designs. To ensure the structural integrity of this type of robust reinforced concrete structures, strength analyses are required. However, the main challenge lies in the modeling of such structures, due to their geometric complexity and the large number of reinforcement elements involved, which results in a high computational cost both in the modeling phase and in the post-processing of results. A simplified numerical model using shell elements was developed, in which the reinforcement is represented as rebar layers, aiming to reduce computational time. The results demonstrated the effectiveness of this methodology, highlighting the stress distribution in both the concrete and the reinforcement layers.
Techno-economic analysis of hydrogen production from offshore wind: The case of Brazil Jeferson Osmar de Almeida, Milad Shadman, Janito dos Santos Ramos, Iago Thiarõ Chaves Bastos, Corbiniano Silva, John Alex Hernandez Chujutalli, Mojtaba Maali Amiri, Clarissa Bergman-Fonte, Gabriella Ramos Lacerda Ferreira, Edvaldo da Silva Carreira, Robson Francisco da Silva Dias, Paulo Emílio Valadão de Miranda, Segen Farid Estefen Energy Conversion and Management, 2024
A Review of Numerical and Physical Methods for Analyzing the Coupled Hydro–Aero–Structural Dynamics of Floating Wind Turbine Systems Mojtaba Maali Amiri, Milad Shadman, Segen F. Estefen Journal of Marine Science and Engineering, 2024 Recently, more wind turbine systems have been installed in deep waters far from the coast. Several concepts of floating wind turbine systems (FWTS) have been developed, among which, the semi-submersible platform—due to its applicability in different water depths, good hydrodynamic performance, and facility in the installation process—constitutes the most explored technology compared to the others. However, a significant obstacle to the industrialization of this technology is the design of a cost-effective FWTS, which can be achieved by optimizing the geometry, size, and weight of the floating platform, together with the mooring system. This is only possible by selecting a method capable of accurately analyzing the FWTS-coupled hydro–aero–structural dynamics at each design stage. Accordingly, this paper provides a detailed overview of the most commonly coupled numerical and physical methods—including their basic assumptions, formulations, limitations, and costs used for analyzing the dynamics of FWTS, mainly those supported by a semi-submersible—to assist in the choice of the most suitable method at each design phase of the FWTS. Finally, this article discusses possible future research directions to address the challenges in modeling FWTS dynamics that persist to date.
MOORING OPTIMIZATION OF FLOATING OFFSHORE WIND TURBINES USING GENETIC ALGORITHM Lucas do Vale Machado, Milad Shadman, Mojtaba Maali Amiri, Segen Farid Estefen Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering OMAE, 2024 Most global wind resources are found in water depths exceeding 60 meters, where using bottom-mounted structures is challenging and costly. Thus, increased the studies on floating offshore wind turbine (FOWT) solutions characterized by complex dynamics between the floating structures and turbines. Nowadays, one key challenge is designing optimum mooring arrangements for large-scale FOWT. A meta-heuristic solution is recommended to solve a complex optimization problem, such as the mooring arrangement of a floating wind turbine. Among these, the Evolutionary Algorithms (EA) use mechanisms inspired by biological evolution. Genetic Algorithm (GA) is a multi-objective search and optimization algorithm based on the concept of Darwin’s theory of evolution, and it belongs to the class of Evolutionary Algorithms. It combines the idea of survival of the fittest with randomized information exchange. Based on the literature, multi-objective optimization algorithms, such as the GA, are commonly used with hydrostatic and frequency-domain models, which are less accurate than a time-domain model for optimization purposes of FOWT. This work addresses the optimization of the mooring system of a FOWT using time-domain simulations in OpenFAST. An in-house code is developed to handle calculations on OpenFAST and apply GA to find the optimal mooring arrangements for specific design variables meeting predefined multi-objectives, respecting all specific constraints for the FOWT. Finally, the optimized arrangements are checked against Ultimate Limit State (ULS) and Accidental Limit State (ALS), performed for the mooring system in damaged condition. The developed optimization process is applied to the UMaine VolturnUS-S semisubmersible platform to maximize power quality and minimize the costs of the lines.
Challenges and alternatives for unmanned underwater vehicular research in the Amazon basin: Towards a more sustainable management of water resources and the environment Jassiel V. H. Fontes, Eliana Brandão da Silva, Rodolfo Silva, Mojtaba Maali Amiri, Edgar Mendoza, Harlysson W. S. Maia, Irving D. Hernández Water and Environment Journal, 2023 The Amazon basin is one of the largest hydrographic systems in the world, possessing a great diversity of natural resources in need of more sustainable water and environmental management. However, as much of what lies beneath the surface of Amazonian waters is still unexplored, underwater exploration technologies are seen as a means of research and monitoring. The present work therefore aims to answer two research questions: What are the current technologies that could be implemented for unmanned underwater research in the Amazon waters? What are the main limitations and existing alternatives for using unmanned underwater vehicles in the rivers of this region to provide more sustainable water and environment management? Our results demonstrate that remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) are possible options in the short and long terms, respectively. The main challenges in implementing these technologies are related to the variations in hydraulic geometry, current velocities and turbidity of the rivers, as well as the preservation of the region's biodiversity. This research can be taken as a starting point for planners and decision makers seeking more sustainable underwater and environmental exploration of the Amazon river system.
A Review of Offshore Renewable Energy in South America: Current Status and Future Perspectives Milad Shadman, Mateo Roldan-Carvajal, Fabian G. Pierart, Pablo Alejandro Haim, Rodrigo Alonso, Corbiniano Silva, Andrés F. Osorio, Nathalie Almonacid, Griselda Carreras, Mojtaba Maali Amiri, Santiago Arango-Aramburo, Miguel Angel Rosas, Mario Pelissero, Roberto Tula, Segen F. Estefen, Marcos Lafoz Pastor, Osvaldo Ronald Saavedra Sustainability Switzerland, 2023
Offshore wind-powered oil and gas fields: A preliminary investigation of the techno-economic viability for the offshore rio de janeiro, brazil Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering OMAE, 2020
