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Increased wind turbine size raises unknowns related to structural flexibility. Moreover, moving to deeper waters, component reliability becomes more critical. This work investigates main bearing response dependence on drivetrain flexibility and wake impingement in a two-turbine wind farm. A 15-MW floating direct-drive turbine is considered. Large eddy simulations (LES) are employed to model neutral, stable and unstable atmospheric conditions at below-rated mean wind speed, while the engineering codes OpenFAST and FAST.Farm simulate turbine and wake behavior. Results indicate significant sensitivities in fatigue estimates to lateral distance between the upstream and downstream turbine. The trends are most substantial in stable conditions, where the waked downwind main bearing sees twice the fatigue damage estimates of the upstream turbine for one position and 50% for another. Main bearing fatigue sensitivity to drivetrain flexibility is minor, while properly including generator rotor inertia loads is important for the axial forces of the locating (axially fixed) bearing, especially in stable conditions. [ABSTRACT FROM AUTHOR]

Abstract Exploring the coordination and analysis of intangible cultural heritage (ICH) and tourism development is a key issue in advancing cultural heritage and conservation in Chinese society. This paper employs panel data from 30 Chinese provinces from 2013 to 2022, utilizing the coupled coordination degree model and the panel vector autoregression (PVAR) model. In terms of provinces and regions, the data investigates the development relationship between intangible cultural heritage and tourism. The results of the study are: 1. The degree of coupling coordination between the two has shown an increasing trend over the ten-year sample data period. In 2021 and 2022, COVID-19 will have a stronger negative impact on the coupling degree. 2. The eastern coastal provinces of China, as well as the municipal areas, have a higher level of coupling coordination. Inland provinces, such as those in central and western China, exhibit relatively lower levels of coordination. The PVAR model data reveals a positive correlation between the interactions generated by intangible cultural heritage. The development of intangible cultural heritage has a particular impact on tourism. Intangible cultural heritage, in turn, depends on its own development. We should strengthen the development of intangible cultural heritage in the future. The study's findings provide theoretical references for the coordinated development of intangible cultural heritage and tourism in China.

Floating offshore wind turbines (FOWTs) have received increasing attention as a crucial component in renewable energy systems in recent years. However, due to the intricate interactions between aerodynamics and hydrodynamics, accurately predicting the performance and response remains a challenging task. This study examines recent advancements in the coupled aero–hydrodynamic numerical simulations for horizontal-axis FOWTs, categorizing existing research by coupling methods: uncoupled, partially coupled, and fully coupled. The review summarizes models, methodologies, and key parameters investigated. Most partially coupled analyses rely on forced oscillation, while the interplay between aerodynamics and elasticity, as well as interactions among multiple FOWTs, remain under-explored. Additionally, this review describes relevant physical model tests, including wave basin tests, wind tunnel tests, and real-time hybrid tests (RTHT). Although RTHT faces issues related to system time delays, they have garnered significant attention for addressing scale effects. The paper compares the three coupling methods, emphasizing the importance of selecting the appropriate approach based on specific design stage requirements to balance accuracy and computational efficiency. Finally, it suggests future research directions, offering a meaningful reference for researchers engaged in studying the aero–hydrodynamic behavior of FOWTs. [ABSTRACT FROM AUTHOR]

Exploring the coordination and analysis of intangible cultural heritage (ICH) and tourism development is a key issue in advancing cultural heritage and conservation in Chinese society. This paper employs panel data from 30 Chinese provinces from 2013 to 2022, utilizing the coupled coordination degree model and the panel vector autoregression (PVAR) model. In terms of provinces and regions, the data investigates the development relationship between intangible cultural heritage and tourism. The results of the study are: 1. The degree of coupling coordination between the two has shown an increasing trend over the ten-year sample data period. In 2021 and 2022, COVID-19 will have a stronger negative impact on the coupling degree. 2. The eastern coastal provinces of China, as well as the municipal areas, have a higher level of coupling coordination. Inland provinces, such as those in central and western China, exhibit relatively lower levels of coordination. The PVAR model data reveals a positive correlation between the interactions generated by intangible cultural heritage. The development of intangible cultural heritage has a particular impact on tourism. Intangible cultural heritage, in turn, depends on its own development. We should strengthen the development of intangible cultural heritage in the future. The study's findings provide theoretical references for the coordinated development of intangible cultural heritage and tourism in China. [ABSTRACT FROM AUTHOR]

Designing the outer containment structures of a nuclear power plant (NPP) often involves considering the potential collision of a military or civilian aircraft. This scenario significantly impacts construction costs and is typically viewed as a beyond-design load case, particularly for civilian aircraft impacts. This paper highlights the advantages of using coupled 3D numerical analysis to comprehensively represent both the aircraft and the structure. Incorporating established nonlinear engineering methods, the coupled analysis also accounts for various parameters such as aircraft type, impact speed, angle, and fuel payload. This approach provides a realistic estimate for beyond-design aircraft impact scenarios. The paper discusses different modeling strategies within the coupled 3D framework, offering insights for effectively evaluating impacts that exceed standard design criteria. Overall, a coupled 3D nonlinear analysis yields the most accurate approximation of structural safety margins for events like commercial aircraft collisions. Its benefits include comprehensive analysis, realistic modeling, detailed understanding of dynamic responses, and flexibility in defining complex load scenarios, applicable to both new and existing structures. However, the drawbacks—such as model complexity, extensive modeling efforts, high computational demands, and challenging result interpretation—must be considered to determine the most suitable analysis method. [ABSTRACT FROM AUTHOR]

This work studies numerically the development of adiabatic shear banding (ASB) during high strain-rate compression of AISI 1045 steel. Plane strain and cylindrical axisymmetric compressions are simulated in LS-DYNA, considering rectangular and cylindrical steel samples, respectively. Also, a parametric analysis in height-to-base ratio is conducted in order to evaluate the effect of geometry and dimensional ratio of the sample on ASB formation. Doubly structural-thermal-damage coupled finite element models are developed for the numerical simulations, implementing the thermo-viscoplastic Modified Johnson–Cook constitutive relation and damage criterion, while further damage-equivalent stress and strain fields are introduced for the damage coupling. The simulations revealed that plane strain compression promotes more ASB formation, providing lower critical strain for ASB initiation and wider and stronger ASBs compared with axisymmetric compression. Further, X-shaped ASBs initially form during plane strain compression, while as deformation increases, they transform into S-shaped ASBs in contrast to axisymmetric compression, where parabolic ASBs are developed. Also, a lower height-to-base ratio leads to greater ASB propensity, reducing critical strain in axisymmetric compression. Finally, thermal softening is found to precede damage softening and dominate the ASB genesis and its early evolution, while in contrast damage softening drives later ASB evolution and its transition to fracture. [ABSTRACT FROM AUTHOR]

This study compares the performance of various foundation systems in expansive soils, such as mats, granular anchor piles, and concrete piles. Expansive soils experience volumetric changes due to moisture fluctuations, which can lead to structural damage. Abaqus software, in conjunction with the SCV approach, is used to analyze soil-foundation interactions. A custom subroutine enhances simulation accuracy by incorporating empirical data on unsaturated clay behavior, matric suction, and variations in effective stress. The method's accuracy is validated by comparing simulation results to field and laboratory experiments. The findings indicate that increasing the applied load on mats decreases overall heave but increases the differential heave. Additionally, higher soil permeability dereases the differential heave of mats. Granular anchor piles outperform concrete piles by more than 50% in highly expansive soils, suggesting a preference for these foundations. This study provides insights into the behavior of expansive soils, which will assist engineers in designing resilient foundation systems for structures. [ABSTRACT FROM AUTHOR]

This paper mainly discusses the dynamics of poroelastic media using the finite element analysis based on the u‐v‐p full formulation, where u${{\bm u}}$, v${{\bm v}}$, and p denote the solid displacement, relative fluid velocity with respect to solid velocity, and pore fluid pressure. It incorporates the effect of relative fluid acceleration with respect to solid acceleration on soil dynamic response. The u${ {\bm u}}$‐v${ {\bm v}}$‐p formulation is first verified through the comparison with the analytical solution. After that, the response of one‐dimensional saturated soil column and two‐dimensional partially saturated soil layer subjected to vertical loading with different combinations of soil permeability and loading frequency are investigated using the analyses with the u${ {\bm u}}$‐v${ {\bm v}}$‐p and u${ {\bm u}}$‐p formulations, based on which the effect of relative pore fluid motion is discussed and the differences in the soil response between two kinds of analysis approaches are examined. Results reveal that the rapid fluid flow has a pronounced effect on soil dynamics and the soil with a greater degree of saturation is more sensitive to the increase of loading frequency and soil permeability. The soil dynamic response can basically be divided into two main categories that represent insignificant and significant flow motion depending on loading frequency and soil permeability. Furthermore, despite vertical loading, horizontal soil response can also be affected by the large relative pore fluid flow when loading frequency and soil permeability are large. In addition, the simplified formulation can still be applicable to predict dynamics of poroelastic media in cases with high loading frequency and low soil permeability. [ABSTRACT FROM AUTHOR]

To optimize the operation of electromagnets used as machines for the traction of large parts or subassemblies, the technological parameters are modified through coupled analyzes and the experimentally obtained results are compared with those simulated with a dedicated software program. In the present work, during the analysis and design process of the electromagnets, special attention was paid to the lost magnetic fluxes, and a new magnetic equivalent circuit of the electromagnet was proposed, in order to improve the electromagnetic characteristics. Ansys software was used for a mechanical analysis coupled with a magnetic one. [ABSTRACT FROM AUTHOR]

Ultrasonic Hot Embossing of polymers is one of the most attractive manufacturing methods of high-quality and complex microparts needed for biological and chemical processes. A little simulation work has been done to study the deformation mechanism and the required load in the Ultrasonic Hot Embossing of polymethyl methacrylate (PMMA). This paper developed a 2D coupled thermo-mechanical finite element model to simulate the forming behavior of the ultrasonic embossing process of PMMA, optimize the mold microfeature corner, and predict the embossing load as well. VDISP ABAQUS subroutine has been used to describe the downward motion of the mold assisted with ultrasonic vibration. The Arbitrary Eulerian-Lagrangian re-meshing technique has been implemented to refine the deformation zone during simulation to avoid divergence due to localized excessive deformation. Embossing load, temperature, stresses, strains, and energy dissipation have been recorded and analyzed. Simulation results revealed that the coupled thermo-mechanical FE Model efficiently captures the deformation behavior and Embossing load. It also proved that a Mold microfeature corner of 20 μm filet radius is recommended to adequately fill out the area around the mold and maintain uniform temperature and strain distributions. [ABSTRACT FROM AUTHOR]

With the increased scale and deployment of floating wind turbines in deep sea environments, jack-up installation vessels are unable to conduct maintenance operations due to limitations in water depth. This has led to the recognition of the advantages of floating cranes in offshore maintenance activities. However, the dynamic coupling between the crane and the floating wind turbine under wave and wind action can result in complex responses, which also relate to complex mooring configurations. The ability to maintain stability during maintenance operations has become a primary concern. In order to address this issue, a method of connecting a floating crane with a floating wind turbine is proposed, simulating the berthing of a floating offshore wind turbine (FOWT) to a crane. Thus, a systematic comparison was conducted with frequency- and time-domain simulation using ANSYS-AQWA software. The simulation results demonstrated the feasibility and dynamic efficiency of this novel berthing approach. Connecting the crane vessel to a floating wind turbine significantly reduced the crane tip movement. Simulations showed that the crane tip movement in the X-, Y-, and Z-directions was reduced by over 30%, which implies that it may be feasible to conduct offshore on-site maintenance operations for the FOWT by using floating crane vessels if the two bodies were properly constrained. [ABSTRACT FROM AUTHOR]

The aim of the paper is the prediction of noise generated by the propeller, hydrodynamic performance and the structural behavior of the marine propeller using two-way fluid–structure interaction (FSI) method at advanced velocities of 6, 8, 10, 12 and 14 Knots. ANSYS-Workbench software is used to establish the coupling between the fluid flow and structural solver. The computed hydrodynamic performance parameters of DTMB 4119 propeller at different advanced velocities and Sound Pressure Level (SPL) at advance coefficient of 0.833 are compared with the data available in the literature and found close agreement. The validated computational methodology is applied for the two-way FSI analysis of the marine propeller. Ffowcs William's–Hawkings (FW–H) model is used to predict the noise spectrum over the frequency range of 0–10 kHz in FSI analysis. Large Eddy Simulation (LES) model is used to capture viscous effects. The speed of the propeller is 1000 rpm and advanced velocity is varied for the systematic study carried out. The effect of advanced velocity on the maximum stress induced in the propeller, deformation of the propeller, acoustic characteristics and hydrodynamic performance of the propeller are studied using FSI method. [ABSTRACT FROM AUTHOR]

In this paper, the coupled sloshing and motion characteristics of a cylindrical floating production storage offloading (CFPSO) are numerically investigated by means of computational fluid dynamics (CFD) tool. The simulations are performed using an in-house CFD solver naoe-FOAM-SJTU which is developed based on OpenFOAM. The active wave generating-absorbing boundary condition (GABC) is utilized for wave generation and absorption. The stabilized k-omega SST turbulence model are used to avoid excessive eddy viscosity near the free surface. CFPSO with and without partially filled liquid tanks in regular waves with different wave periods are simulated and vertical planar motions such as surge, heave and pitch response amplitude operators (RAOs) are compared. Forces due to liquid sloshing and wave loads are extracted and analyzed. The free surface motions inside liquid tanks in one wave period presented to explain the motion characteristics. [ABSTRACT FROM AUTHOR]

AbstractAiming at significant disadvantages of finite element analysis (FEA) performed in coupled multiphysics field calculation, including high computing cost and strong dependency on meshing quality. Taking a high-speed permanent magnet synchronous motor (P MSM) as an example, an approach combining FEA with optimized meshless method is proposed to solve the heat transfer problem. Firstly, electromagnetic losses under rated and 1.2 times overloaded operation conditions are calculated using FEA respectively. Secondly, three-dimensional FEA flow models considering the influence of viscosity varying with temperature are established. Thirdly, convective heat transfer coefficients are calculated as the boundary condition, after which the electromagnetic losses as heat sources are mapped to the threedimensional steady-state temperature field calculations using FEA and conventional meshless method respectively. Applying the above two methods, a singular boundary method (SBM) is employed to replace the temporal derivative term of the transient calculation equation. Finally, to mitigate the illconditioned matrix appearing in the conventional meshless method coupled with FEA, an optimized meshless method is proposed to recalculate the heat transfer equation. After that, the calculation results of the above methods are compared with experimental results. This research is beneficial for the multiphysical coupling analysis of electrical equipment with complex structures considering nonlinear factors. [ABSTRACT FROM AUTHOR]

Although stone-column embankments on soft ground have been widely studied, there is a limited number of studies in the literature in which overall stability is analysed when geosynthetic reinforcement is also incorporated at the embankment base. In the paper, a finite element-based stability analysis method is proposed and applied to analyse overall stability of geosynthetic-reinforced and stone column-supported embankments on soft soils. Fully mechanical-hydraulic coupled analyses are performed, a critical state model is used for soil constitutive behaviour and hardening non-linear elastoplastic models are incorporated to model the geosynthetics and soil-geosynthetic interfaces. Comparisons of the proposed method with other published methods are included in which the influence of the geosynthetic constitutive curve and of the area replacement factor of stone columns are analysed. Regarding the geosynthetic constitutive curve, its influence on other key variables—namely, excess pore pressure, geosynthetic tensile force, stress concentration ratio, settlement and horizontal displacement—is also analysed. [ABSTRACT FROM AUTHOR]

With the continuous growth of energy demand, the advantages of nuclear power, such as high energy density, low emissions, and cleanliness, are gradually highlighted. However, the increasing capacity of the turbine generator in nuclear power plants has led to greater losses and critical heating issues. Designing an effective cooling system plays an important role in improving the rotor's heat dissipation ability, especially under the condition of limited rotor space. In this study, the cooling effects of the rotor using a radial straight-type cooling structure and a composited radial–axial–radial cooling structure are compared and analyzed for a 1555 MVA hydrogen-cooled nuclear turbine generator. Three-dimensional fluid thermal coupled models of the rotor with both cooling structures are established, and corresponding boundary conditions are provided. The models are solved using the finite volume method. The flow law of cooling hydrogen gas inside the rotor and the temperature distribution of various parts of the rotor are studied in detail. Compared with the radial straight-type cooling structure, adopting the composited radial–axial–radial cooling structure can reduce the average temperature of the rotor field windings by 4.5 °C. The research results provide a reference for the design and optimization of the rotor cooling system for large-capacity nuclear turbine generators. [ABSTRACT FROM AUTHOR]

This paper investigates numerically the effect of damage evolution on adiabatic shear banding (ASB) formation and its transition to fracture during high-speed blanking of 304 stainless steel sheets. A structural-thermal-damage-coupled finite element (FE) analysis is developed in LS-DYNA considering the modified Johnson–Cook thermo-viscoplastic model for both plasticity flow rule and damage law, while further, a temperature-dependent fracture criterion is implemented by introducing a critical temperature. The modeling approach is initially validated against experimental data regarding the fracture profile and ASB width. Next, FE simulations are conducted to examine the effect of strain rate and temperature dependence on damage law, while the effect of damage coupling is also evaluated, aiming to highlight the connection between thermal and damage softening and attribute them a specific role regarding ASB formation and transition to fracture. Also, the influence of dynamic recrystallization (DRX) softening is studied macroscopically, while further, a parametric analysis of the Taylor–Quinney coefficient is conducted to highlight the effect of plastic work-to-internal heat conversion efficiency on ASB formation. The results revealed that the implementation of damage coupling reacts to reduced ASB width and provides an S-shaped fracture profile, while it also decreases the peak force and results in an earlier fracture. Both findings are enhanced when accounting further for DRX softening and a higher value of the Taylor–Quinney coefficient. Finally, the simulations indicated that thermal softening precedes damage softening, showing that the temperature rise is responsible for ASB initiation, while instead, damage evolution drives ASB propagation and fracture. [ABSTRACT FROM AUTHOR]

Floating offshore wind turbines (FOWTs) have received increasing attention as a crucial component in renewable energy systems in recent years. However, due to the intricate interactions between aerodynamics and hydrodynamics, accurately predicting the performance and response remains a challenging task. This study examines recent advancements in the coupled aero–hydrodynamic numerical simulations for horizontal-axis FOWTs, categorizing existing research by coupling methods: uncoupled, partially coupled, and fully coupled. The review summarizes models, methodologies, and key parameters investigated. Most partially coupled analyses rely on forced oscillation, while the interplay between aerodynamics and elasticity, as well as interactions among multiple FOWTs, remain under-explored. Additionally, this review describes relevant physical model tests, including wave basin tests, wind tunnel tests, and real-time hybrid tests (RTHT). Although RTHT faces issues related to system time delays, they have garnered significant attention for addressing scale effects. The paper compares the three coupling methods, emphasizing the importance of selecting the appropriate approach based on specific design stage requirements to balance accuracy and computational efficiency. Finally, it suggests future research directions, offering a meaningful reference for researchers engaged in studying the aero–hydrodynamic behavior of FOWTs.

Ferrography is a significant means of wear particle detection for mechanical equipment. In view of the issue that the wear particle deposition process by a ferrograph is difficult to accurately adjust to avoid accumulation or escape, the deposition behavior of wear particles coupled with the magnetic, fluid and solid field in a ferrograph is studied by the finite element method. The wear particle force and its deposition principle are first analyzed, and the theoretical deposition law is obtained. By building 3D finite element model, setting the magnetic, flow field and wear particle parameters, the coupled simulation based on the particle tracking is carried out. According to the process of wear particles flowing out of the oil tube and then depositing on the ferrogram slide, the effect of oil pressure, viscosity, density, ferrogram slide inclination angle, distance between oil tube and ferrogram slide and the particle release mode on the particle deposition behavior is studied. Based on the velocity and displacement of particles, the reasonable parameter ranges are obtained, and the sensitive variables are determined. In order to verify the numerical law through experiments, the area and perimeter of wear particles are adopted, meanwhile the oil viscosity is selected as the adjustable parameter, and the tested results prove the numerical simulation correct. [ABSTRACT FROM AUTHOR]

Buildings located on hill slopes are subjected to additional effects under seismic action compared with those on flat ground. This article presents Incremental Dynamic Analyses of coupled building‐slope systems incorporating topographic amplification, nonlinear slope movement and irregular structural configuration of hill‐side buildings. Two different stable slopes, supporting single and multiple adjacent ductile moment resisting reinforced concrete frame buildings with step‐back configuration, prevalent in Indian and Chinese hilly regions, are modelled and analyzed using the finite element software ABAQUS. A suite of 21 ground motions is incrementally scaled and used to compute the seismic response of the coupled system. Fragility curves for different damage states, derived as lognormal probability distributions in terms of three different Intensity Measures (IMs) and damage probabilities of the considered buildings, are derived and compared. The spectrum‐based IMs (e.g., spectral acceleration at fundamental period, and average of the spectral acceleration over a period range) result in lower record‐to‐record variability, compared with the peak ground acceleration as the IM. The results reveal that ignoring the effect of slope significantly underestimates the fragility for all the damage states. [ABSTRACT FROM AUTHOR]

Floating offshore multi-wind turbines (FOMWTs) are an interesting alternative to the up-scaling of wind turbines. Since this is a novel concept, there are few numerical tools for its coupled dynamic assessment at the present time. In this work, a numerical framework is implemented for the simulation of multi-rotor systems under environmental excitations. It is capable of analyzing a platform using leaning towers that handle wind turbines with their own features and control systems. This tool is obtained by coupling the seakeeping hydrodynamics solver SeaFEM with the single wind turbine simulation tool OpenFAST. The coupling of SeaFEM provides a higher fidelity hydrodynamic solution, allowing the simulation of any structural design using the finite element method (FEM). Additionally, a methodology is proposed for the extension of the single wind solver, allowing for the analysis of multi-rotor configurations. To do so, the solutions of the wind turbines are computed independently using several OpenFAST instances, performing its dynamic interaction through the floater. This method is applied to the single turbine Hywind concept and the twin-turbine W2Power floating platform, supporting NREL 5-MW wind turbines. The rigid-body response amplitude operators (RAOs) are computed and compared with other numerical tools. The results showed consistency in the developed framework. An agreement was also obtained in simulations with aerodynamic loads. This resulting tool is a complete time-domain aero–hydro–servo–elastic solver that is able to compute the combined response and power generation performance of multi-rotor systems. [ABSTRACT FROM AUTHOR]

With the increased scale and deployment of floating wind turbines in deep sea environments, jack-up installation vessels are unable to conduct maintenance operations due to limitations in water depth. This has led to the recognition of the advantages of floating cranes in offshore maintenance activities. However, the dynamic coupling between the crane and the floating wind turbine under wave and wind action can result in complex responses, which also relate to complex mooring configurations. The ability to maintain stability during maintenance operations has become a primary concern. In order to address this issue, a method of connecting a floating crane with a floating wind turbine is proposed, simulating the berthing of a floating offshore wind turbine (FOWT) to a crane. Thus, a systematic comparison was conducted with frequency- and time-domain simulation using ANSYS-AQWA software. The simulation results demonstrated the feasibility and dynamic efficiency of this novel berthing approach. Connecting the crane vessel to a floating wind turbine significantly reduced the crane tip movement. Simulations showed that the crane tip movement in the X-, Y-, and Z-directions was reduced by over 30%, which implies that it may be feasible to conduct offshore on-site maintenance operations for the FOWT by using floating crane vessels if the two bodies were properly constrained.

The dynamic characteristics and structural responses of operation and grid loss offshore wind turbines (OWTs) under onshore and seafloor earthquakes are analyzed based on the established coupled seismic analysis model. In addition to the remarkable influence of the rotor system on the responses of the operation OWT under earthquakes, interactions among the natural modes of the grid loss OWT in the fore-aft and side-to-side directions are revealed. By comparing with the onshore earthquakes, the more significant differences of structural response are observed under the selected seafloor earthquakes, due to the longer duration and more abundant energy distribution around the natural frequencies of OWT. Concurrently, a multiple tuned mass damper (MTMD) is designed and applied to the operation and grid loss OWTs. Then, the comparisons of the mitigation effects under onshore and seafloor ground motions are carried out, and the necessity of applying seafloor ground motions to OWTs are proved. Moreover, in comparison to the operation OWT, more effective reductions are observed for the grid loss OWT under onshore and seafloor earthquakes using the designed MTMD. Therefore, the combined shutdown procedures and MTMD vibration control strategy is suggested for OWTs under earthquakes. [ABSTRACT FROM AUTHOR]

Floating photovoltaics (FPVs) have been developed rapidly in the past few years and will gradually become the "third pillar" of the photovoltaic industry. To better understand the performance of FPV floaters, this paper provides an in-depth study on the hydrodynamics of a single FPV module and the coupling effects of multiple modules. The results show that a conventional frequency domain approach, which includes both panel and Morison models, may not necessarily provide realistic results. Even after adding an additional damping matrix for the floaters based on empirical values from the oil and gas (O&G) industry, and a free surface damping model between the pontoons, the responses were still not convincing. Therefore, a nonlinear time-domain hydrodynamic solver was introduced. Further studies and comparisons were performed to understand the behavior of the module, and some updated damping coefficients were summarized. Thereafter, a multibody hydrodynamic model was built to check the coupling effects. With the additional damping surface on the gap surface among the modules, some attempts were made to derive reasonable results, when the model test was not available. Preliminary studies of both a scaled-down system (with 9 modules and mooring lines) and a full-scale system (with 90 modules, buoys, and mooring systems) were also investigated, and some initial results were demonstrated. [ABSTRACT FROM AUTHOR]

With the continuous growth of energy demand, the advantages of nuclear power, such as high energy density, low emissions, and cleanliness, are gradually highlighted. However, the increasing capacity of the turbine generator in nuclear power plants has led to greater losses and critical heating issues. Designing an effective cooling system plays an important role in improving the rotor’s heat dissipation ability, especially under the condition of limited rotor space. In this study, the cooling effects of the rotor using a radial straight-type cooling structure and a composited radial–axial–radial cooling structure are compared and analyzed for a 1555 MVA hydrogen-cooled nuclear turbine generator. Three-dimensional fluid thermal coupled models of the rotor with both cooling structures are established, and corresponding boundary conditions are provided. The models are solved using the finite volume method. The flow law of cooling hydrogen gas inside the rotor and the temperature distribution of various parts of the rotor are studied in detail. Compared with the radial straight-type cooling structure, adopting the composited radial–axial–radial cooling structure can reduce the average temperature of the rotor field windings by 4.5 °C. The research results provide a reference for the design and optimization of the rotor cooling system for large-capacity nuclear turbine generators.

The influence of excavation rate, geometric layout, and hydraulic conductivity of basal and retained soils on the fully coupled solid–fluid behavior of braced excavations in cohesive soils is presented. Fully coupled excavation analyses were performed using the hypoplasticity clay model to reproduce the constitutive soil behavior combined with Biot's consolidation theory. A method aimed at predicting excavation-induced ground movements using excess pore-water pressure ratios as a function of site-specific groundwater considerations is presented for the determination of the recommended type of excavation analysis (i.e., drained, partially drained, or undrained). Results obtained from the numerical simulations indicated that excavation rate to hydraulic conductivity ratios, ER/k , smaller than 0.1 and larger than 10,000 can be analyzed under drained and undrained conditions, respectively. The proposed method was validated with published case histories, and its ability to estimate excavation performance in terms of excess pore-water pressures and excavation rates is presented in this paper. [ABSTRACT FROM AUTHOR]

In the EU, the Water-Cooled Lithium Lead (WCLL) Breeding Blanket (BB) concept is one of the candidates for the design of the DEMO reactor. From the past campaign of analysis emerged that the thermal-induced stress led to the failure in the verification of the RCC-MRx structural criteria. Hence, in this paper the classic conceptual design approach, based on a pure FEM thermal and structural analysis, is compared to a coupled thermofluid-dynamic/structural one. Even though the coupled approach requires tremendous modelling effort and computational burden, it surely allows determining the thermal field with a higher level of detail than the FEM analysis. Therefore, in this work, the focus is put on the impact of a more detailed thermal field on the DEMO WCLL BB global structural performances, focusing on the Top Cap region of its Central Outboard Blanket segment. The obtained results have allowed confirming the soundness of the design solution of the Top Cap region, except for concerns arising on the mass flow rate distribution. Moreover, results have shown that, globally, the pure FEM approach allows for obtaining more conservative results than the coupled one. This is a positive outcome in sight of the follow-up of the DEMO WCLL BB design, as it will be still possible adopting the pure FEM approach to quickly down-select design alternatives, using the most onerous coupled approach to finalise the most promising. [ABSTRACT FROM AUTHOR]

Marine propellers have complex geometry and their performance is determined by costly and time consuming open water experiments. Use of numerical techniques helps researchers in effective design of propellers. Several approaches are used that predicted either hydrodynamic and acoustic response or structural response. Two-way fluid-structure interaction (FSI) analysis is a very useful approach providing all three responses which helps in the design, analysis and optimization of a propeller. The objective of this paper is to predict the hydro-elastic response of a propeller using two-way FSI on a 0.2m diameter, DTMB-4119 propeller using ANSYS software. Two-way FSI analysis is carried out using system coupling approach that transfers the data between the structural and fluid solvers. The turbulence effects are captured using the large-eddy simulation (LES) model and the Ffowcs Williams Hawkings (FWH) acoustic model is used for evaluating the sound pressure level (SPL) generated by propeller. Analysis is extended to evaluate the hydro-elastic and acoustic response of the propeller after validating the hydrodynamic performance with the experimental result in the literature. The results from Two-way FSI analysis are in close agreement when compared with the one-way FSI analysis. Two-way FSI can accommodate the peak value of stress and deformation developed during the initial part of the transient solution which is important in the design of propeller. This study reveals that metallic (NAB) propeller can be replaced by a composite propeller. The acoustic response from two-way FSI analysis will be more realistic due to the consideration of hydro-elastic effect of propeller.

The medium and long-term demand prediction for water resources is critical to the country's macro-allocation of water resources and the formulation of a long-term regional economic development strategy. However, the official prediction report of China's water resources was created ten years ago, and its results are far from accurate in practice making it difficult to direct China's water resource planning in the coming ten years. By introducing the demand forecasting method for the first time, this study built a mathematical prediction model that integrates "data constraint + mathematical prediction + actuarial prediction". The conclusions are as follows: (1) The new method developed in this research is more accurate than previous prediction methods and has a higher degree of matching with actual data. Despite the problem of trend extrapolation, this model can accurately understand the long-term trend. However, the amount of data must be calculated. (2) China's consumption of total water, agricultural water, industrial water, domestic water, and ecological water will predict to be 552.9 billion m3, 319.1 billion m3, 95.7 billion m3, 95.5 billion m3 and 42.6 billion m3 in 2030, respectively, as well as 504.7 billion m3, 281.1 billion m3, 61.4 billion m3, 101.4 billion m3, and 60.8 billion m3 in 2050, respectively, indicating obvious structural changes. (3) China's industrial structure evolves frequently; therefore, water resource forecasting must account for changes in industrial structure as well as geographical variances. In North China, agricultural water demand will fall, but ecological water investment will rise. The planning and distribution of the nation's water resources will significantly be influenced theoretically and practically by the development of this methodology study. This method is universal and can be used for long-term prediction of future water demand in other countries. [ABSTRACT FROM AUTHOR]

To realize multi-purpose exploration of marine resources, a novel design consisting of a monopile offshore wind turbine and steel aquaculture cage in an integrated structure is proposed in this paper; the structure is denoted as MOWTAC. Based on the theories of the screen model, a hydrodynamic analysis module is developed in the OWT simulation tool FASTv8. Then, in combination with a seismic analysis module, the fully coupled analysis model of the MOWTAC is established in the updated FAST v8. Based on the coupled model, the dynamic characteristics and coupling mechanisms of the MOWTAC under earthquake, wind, and wave loads are investigated. A tuned mass damper (TMD) is applied to the MOWTAC under earthquakes, and the influence of the TMD parameters on the mitigation effects is studied. Furthermore, a multiple tuned mass damper (MTMD) with various tuning frequencies is applied, and comparisons with the TMD are carried out. Based on the reduction of seismic responses using the TMD and MTMD, vibration control methods and related design parameters are recommended for the MOWTAC under earthquake, wind, and wave loads. [ABSTRACT FROM AUTHOR]

A two-degree-of-freedom (two-DOF) equation of motion was derived in the frequency domain using a substructuring technique for efficiently calculating the in-structure response spectrum (ISRS) considering equipment–structure interaction. The model of the primary structure was condensed into a mechanical impedance function and combined with the equipment represented by a single-degree-of-freedom oscillator in the frequency domain. This condensed two-DOF system is applied to the efficient calculation of the ISRS considering the equipment–structure interaction without repeated analysis of the coupled model with full DOFs. This coupled analysis procedure was applied to a finite element model of an auxiliary building in a nuclear power plant to validate both the accuracy and impact on the equipment response. Finally, the adequacy of three representative decoupling criteria on the necessity of coupled analysis was investigated by applying those criteria to the auxiliary building example. [ABSTRACT FROM AUTHOR]