Floating offshore wind turbines (FOWT) generate green renewable energy and are a vital part of the modern offshore wind energy industry. Robust predicting extreme offshore loads during FOWT operations is an important safety concern. Excessive structural bending moments may occur during certain sea conditions, posing an operational risk of structural damage. This paper uses the FAST code to analyze offshore wind turbine structural loads due to environmental loads acting on a specific FOWT under actual local environmental conditions. The work proposes a unique Gaidai-Fu-Xing structural reliability approach that is probably best suited for multi-dimensional structural responses that have been simulated or measured over a long period to produce relatively large ergodic time series. In the context of numerical simulation, unlike existing reliability approaches, the novel methodology does not need to re-start simulation again each time the system fails. As shown in this work, an accurate forecast of the probability of system failure can be made using measured structural response. Furthermore, traditional reliability techniques cannot effectively deal with large dimensionality systems and cross-correction across multiple dimensions. The paper aims to establish a state-of-the-art method for extracting essential information concerning extreme responses of the FOWT through simulated time-history data. Three key components of structural loads are analyzed, including the blade-root out-of-plane bending moment, tower fore-aft bending moment, and mooring line tension. The approach suggested in this study allows predicting failure probability efficiently for a non-linear multi-dimensional dynamic system as a whole.

Novel coronavirus disease 2019 (COVID-19) is a contagious disease with high transmissibility to spread worldwide with considerable morbidity and mortality and presents an enormous burden on worldwide public health. Due to the non-stationarity and complicated nature of epidemic waves, it is challenging to model such a phenomenon. Few mathematical models can be used because epidemic data are generally not normally distributed. This paper describes a novel bio-system reliability approach, particularly suitable for multi-regional environmental and health systems, observed over a sufficient period of time, resulting in a reliable long-term forecast of the highly pathogenic virus outbreak probability. Traditional statistical methods dealing with temporal observations of multi-regional processes do not have the advantage of dealing efficiently with extensive regional dimensionality and cross-correlation between different regional observations. For this study, COVID-19 daily numbers of recorded patients in most affected US states were chosen. This work aims to benchmark state of the art method, which makes it possible to extract the necessary information from dynamically observed patient numbers, while taking into account relevant territorial mapping. The method proposed in this paper opens up the possibility of accurately predicting epidemic outbreak probability for multi-regional biological systems.

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Robust prediction of extreme motions during wind farm support vessel (WFSV) operation is an important safety concern. In particular, it is important to study safety of operation in random sea conditions during WFSV docking against the wind tower, while workers are able to get on to the tower. Docking is performed by thrusting the vessel fender against the wind tower (the alternative docking maneuver by hinging is not studied here). In this paper, the finite element software AQWA has been used to analyze the vessel response due to hydrodynamic wave loads, acting on a specific maintenance ship under actual sea conditions. Excessive motions may occur during certain sea conditions, posing a risk to the crew transfer operation. The authors have primarily focused on the statistical analysis rather than the dynamics of the problem. This paper presents a novel method for estimating bivariate statistics, based on Monte Carlo simulations (or measurements if available). The bivariate average conditional exceedance rate (ACER2D) method is briefly outlined. The ACER2D method offers an accurate estimation of bivariate statistics, utilizing the available data efficiently. Two dimensional probability contours, corresponding to large return periods, are obtained by the ACER2D method. Based on the overall performance of the presented method, it is seen that the ACER2D method provides an efficient and accurate prediction of extreme return period contours. The described approach may serve as a useful tool for vessel design, facilitating optimization of boat parameters in order to minimize excessive vessel motions.

Two novel methods are being outlined that, when combined, can be used for spatiotemporal analysis of wind speeds and wave heights, thus contributing to global climate studies. First, the authors provide a unique reliability approach that is especially suited for multi-dimensional structural and environmental dynamic system responses that have been numerically simulated or observed over a substantial time range, yielding representative ergodic time series. Next, this work introduces a novel deconvolution extrapolation technique applicable to a wide range of environmental and engineering applications. Classical reliability approaches cannot cope with dynamic systems with high dimensionality and responses with complicated cross-correlation. The combined study of wind speed and wave height is notoriously difficult, since they comprise a very complex, multi-dimensional, non-linear environmental system. Additionally, global warming is a significant element influencing ocean waves throughout the years. Furthermore, the environmental system reliability method is crucial for structures working in any particular region of interest and facing actual and often harsh weather conditions. This research demonstrates the effectiveness of our approach by applying it to the concurrent prediction of wind speeds and wave heights from NOAA buoys in the North Pacific. This study aims to evaluate the state-of-the-art approach that extracts essential information about the extreme responses from observed time histories.

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As a vital key part of the modern offshore wind energy industry, floating offshore wind turbines (FOWT) are built to generate green renewable energy. Robust prediction of extreme loads during FOWT operation is an important safety concern. In this paper, the FAST code has been used to analyze offshore wind turbine internal bending moments due to environmental hydrodynamic wave loads, acting on a specific FOWT under actual local sea conditions. This paper advocates a computationally efficient Monte Carlo based methodology for estimating extreme load or response statistics, based on simulations or measurements. For this purpose, the averaged conditional exceedance rate (ACER) method is proposed. The methodology provides for accurate extreme value prediction, representing an efficient use of all available data. In this study the estimated return level values, obtained by the ACER method, are compared to the corresponding return level values obtained by the Gumbel method. Based on the overall performance of the proposed method, it is concluded that the ACER method can provide more robust and accurate prediction of extreme structural loads. The described approach may be well used at the design stage, while defining optimal wind turbine parameters that would minimize potential FOWT mechanical damage due to excessive environmental loadings.