Search

ObjectiveThe open area of the superstructure of a luxury cruise ship has a complex spatial layout and appearance modeling. In this study, the wind load and flow field characteristics in this area are accurately simulated to guide cruise ship design. MethodsThe realizable k−ε turbulence model and substructure method in the Reynolds time-average method are used to numerically simulate the flow field characteristics of the whole cruise ship and the open area of the superstructure, and wind tunnel experiments are carried out for verification. ResultsThe appearance and spatial layout of the open area of the superstructure have an important impact on the flow field characteristics of the cruise ship, and the substructure simulation method can accurately simulate the flow field characteristics of the local area. ConclusionsWhen designing cruise ships, the overall shape of the superstructure should be streamlined and the height difference and spacing between adjacent structures in the open area should not be too large. The results of this study can provide guiding references for cruise ship design.

ObjectiveThis paper aims to reveal the influence of the afterburning effect of explosive materials in confined space explosion. MethodsA series of TNT blast tests are performed in a confined cabin filled with two different atmospheres, air and nitrogen. The temperature, pressure-time histories and deflection of the blast-loaded steel plate are recorded. The relationship between the deformation of the target plate and the energy released by the explosive is established. On this basis, a TNT equivalent method is proposed which takes into account the afterburning effect in a confined cabin. ResultsThe pressure, temperature and dynamic response of the target plate are significantly lower in the nitrogen environment than in the air environment due to the difference in the amount of energy released by the combustion of the explosive material. Thus, the energy released by the burning of TNT explosive materials and their enhancement effects should be considered in blast load analysis. ConclusionThe validity and applicability of the method are illustrated through a comparison with the existing TNT equivalent method based on quasi-static pressure.

The traditional processing method of peanuts has drawbacks such as high energy consumption, slow flavor absorption, and long processing cycles, to get better flavor of pepper-flavored peanut kernel snack food, this study used the vacuum technology combining with traditional technology to optimize by examining the effect of negative pressure time, negative pressure times and vacuum degree on the content of zanthoxylamide and sensory score using a combination of single factor method and response surface design. The results showed that the order of influence of various factors on pepper-flavored peanut kernels was negative pressure time>negative pressure frequency>vacuum degree. The optimal process parameters were negative pressure time of 100 seconds, negative pressure frequency of 6 times, and vacuum parameter of 0.80 MPa. The protein and fat content of pepper-flavored peanut kernels produced by this optimal process were 27% and 57%, respectively. The peroxide value and acid value meet national standards, and the sensory score was 93.1 points. This study would provide a reference for promoting the standardized processing of the entire nut snack food industry chain, and promoted the sustainable development of the nut snack food industry.

The fat, protein and other compounds in konjac powder limit the application of konjac glucomannan. Konjac glucomannan with relatively high purity could be applied in food, medicine and other sectors. This research aimed to optimize the ultrasonic assisted purification process of glucomannan from konjac powder with ethanol. The significance effects of five relevant factors including the ratio of konjac powder to ethanol, ethanol concentration, ultrasonic time, power and temperature were analyzed based on single factor analysis of variance. The first three aforementioned factors were selected for further analysis their significant effects on the purity of glucomannan. Moreover, the relevant factors were optimized via response surface model fitting. The final optimized parameters were as follows: 1:102 (g/mL) for the ratio of konjac powder to ethanol, 73% ethanol, 55 min ultrasonic time, 175 W ultrasonic power, 50 ℃ ultrasonic temperature. The content of konjac glucomannan under the process condition was 88.1%, which was close to the predicted value, and the purification process of glucomannan from konjac powder was feasible. The structure of the samples before and after optimization were measured by infrared spectroscopy and X-ray diffraction with no significant difference. The content of konjac glucomannan in the purified konjac powder by this process was significantly higher than that in the unpurified one, and the structure was less affected. Results from this study could provide theoretical support for efficient utilization of konjac glucomannan and development of relevant functional products.

ObjectivesAlthough the fluid-structure interaction calculation method can better simulate the ship collision process, it requires a longer calculation time. To address this problem, a simplified numerical calculation method is proposed. MethodsThe local cabin section of a ship is taken as the object to carry out water collision experiments under various operating conditions. Force sensors and non-contact measurement based on high-speed photography technology are used to obtain the collision force and motion time history data of the ship. The collision contact force and acceleration response data are then analyzed, and arbitrary Lagrange−Euler (ALE) coupled fluid-solid numerical computational analysis is carried out on the experimental process. The effect of the water on the impacting ship in the collision process is then simplified to the equivalent mass, and the effect on the impacted ship is simplified to the equivalent resistance, which acts on the non-impacting side of the impacted ship in the form of surface force to hinder the movement of the impacted ship. Numerical calculations that do not involve the water-structure coupling process are then carried out on the basis of the simplified method. ResultsThe results show that the errors between the peak collision force and the experimental values for each condition obtained by the simplified calculation method are within 5%, and the calculation time required by this method is much smaller than that of the ALE fluid-structure interaction algorithm ConclusionsThe proposed simplified numerical calculation method can provide useful references for realizing the efficient calculation of ship structure collision response.

ObjectiveIn order to improve the safety of ship navigation, this study focuses on virtually aided ship navigation strategies.MethodsTwo different inland river routes are chosen for the simulation of virtually aided ship navigation models based on the fluid-structure interaction mechanism, while taking the navigation rules and flow details of the rivers into consideration. The simulation of the ship sailing process on a typical inland river route under specific current conditions provides the corresponding virtually aided navigation plan in which the ship's velocity, location and course are obtained in a timely manner. ResultsIt is found that the simulation method established on the basis of Fluent can be used to solve the problems of multi-degree-of-freedom motion and fluid-structure interaction. When sailing through bends or branches, steering with a small rudder angle over long distances ensures safe navigation and prevents speed reduction and significant lateral displacement.ConclusionThe proposed method can be effectively combined with the flow field information of digital channels to simulate the ship sailing process, thereby providing data support for the decision-making of intelligent navigation on inland river routes.

ObjectiveThis paper investigates the coupling effect of ship nonlinear wave load and transient high-amplitude slamming load in view of the whipping response of ships under extreme sea conditions. MethodsA two-way computational fluid dynamics-finite element method (CFD-FEM) fluid-structure interaction method is used to carry out the numerical simulation of an S175 container ship, and the results are compared with the test results and 2D linear strip theory. The testing of a segmented ship model with a variable cross-section elastic backbone is carried out, and the analysis of the bow's slamming load and high-frequency nonlinear whipping characteristics is undertaken based on the two-way CFD-FEM fluid-structure interaction method. The results are then verified through comparison with the model test. ResultsThe influence of wave slamming load on the whipping response of the bow cannot be ignored. The second order high-frequency component induced by whipping accounts for 59.86% of the low-frequency wave bending moment in sea state 6. ConclusionsThe proposed two-way CFD-FEM fluid-structure interaction method can calculate the whipping response accurately. The nonlinear wave-induced load and dynamic structural response of the ship under extreme sea conditions are affected by the transient slamming load of the bow. In conclusion, the high-frequency whipping response should be taken into consideration in the safety design and assessment stages of ship structures.

ObjectiveThis paper aims to study the wind-induced noise of typical rods in the open areas of cruise ships. MethodsThe numerical simulation of aerodynamic noise and wind-induced vibration noise is carried out using computational fluid dynamics (CFD) combined with the acoustic analogy method and vibro-acoustic coupling method in order to explore the generation mechanisms and characteristics of the two kinds of noise. Results Under different wind speeds, the maximum frequency of aerodynamic noise is dominated by the vortex shedding frequency, while the maximum frequency of wind-induced vibration noise is dominated by the natural frequency of the structure. The aerodynamic noise of three different cross-section rods is generally greater than that of wind-induced vibration noise, and the aerodynamic noise of square rods is the greatest. Under large flexibility, when the fluctuating pressure frequency of the rod is close to the natural frequency, the wind-induced vibration noise will be close to or even exceed the aerodynamic noise. ConclusionsIn the design of typical rods to be applied in the open areas of cruise ships, in order to reduce wind-induced noise, circular rods should be selected, square rods should be avoided, reasonable rod sizes should be selected and the vortex shedding frequency of the rods should not be close to the natural frequency.

BackgroundPostoperative delirium (POD) is a common anesthetic side effect in cardiac surgery. However, the role of oxygen saturation monitoring in reducing postoperative delirium has been controversial. Therefore, this meta-analysis aimed to analyze whether NIRS monitoring during cardiac surgery under cardiopulmonary bypass could reduce the incidence of postoperative delirium.MethodsPubMed, Web of Science, Cochrane Library, Embase and China National Knowledge Infrastructure (CNKI) databases were systematically searched using the related keywords for randomized-controlled trials (RCTs) published from their inception to March 16, 2024. This review was conducted by the Preferred Reporting Project and Meta-Analysis Statement (PRISMA) guidelines for systematic review. The primary outcome was postoperative delirium, and the second outcomes included the length of ICU stay, the incidence of kidney-related adverse outcomes, and the incidence of cardiac-related adverse outcomes.ResultsThe incidence of postoperative delirium could be reduced under the guidance of near-infrared spectroscopy monitoring (OR, 0.657; 95% CI, 0.447–0.965; P = 0.032; I2 = 0%). However, there were no significant differences in the length of ICU stay (SMD, 0.005 days; 95% CI, −0.135–0.146; P = 0.940; I2 = 39.3%), the incidence of kidney-related adverse outcomes (OR, 0.761; 95% CI, 0.386–1.500; P = 0.430; I2 = 0%), and the incidence of the cardiac-related adverse outcomes (OR, 1.165; 95% CI, 0.556–2.442; P = 0.686; I2 = 0%) between the two groups.ConclusionNear-infrared spectroscopy monitoring in cardiac surgery with cardiopulmonary bypass helps reduce postoperative delirium in patients.Systematic Review RegistrationPROSPERO, identifier, CRD42023482675

ObjectiveWelding is a common method for connecting ship structures, but it obviously affects their acoustic and vibration characteristics. Thus, it is necessary to study the influence of welding process parameters on the acoustic and vibration characteristics of structures. MethodIn this paper, the thermo-elastoplastic finite element method and acoustic-structure coupling finite element method are combined to study the influence of welding parameters on the acoustic and vibration characteristics of typical ship stiffened plate structures. ResultsThe results show that welding residual stress is significantly affected by welding input power and speed. Higher welding input power and lower welding speeds both result in a larger welding residual stress distribution range which causes changes to the natural frequency, vibration response and radiated sound pressure of typical stiffened plate structures. ConclusionWelding residual stress should be analyzed to determine the acoustic and vibration response of low-damping welded structures, thereby providing guidance for the formulation of low-noise welding processes.

This paper reviews research on vibration and noise in the open deck spaces of large cruise ships. In the first part, the main functions, features and vibration and noise source characteristics of typical leisure and entertainment areas in open deck spaces are analyzed and categorized. The second part outlines sub-model methods adapted to predict structural vibration caused by wind in open spaces, and the research progress of wind-induced vibration is introduced. An analysis is then made of the advantages and disadvantages of different prediction methods, including discrete methods (FEM/BEM/IEM), statistical energy analysis (SEA) and geometric acoustic method (i.e. ray tracing), in the two dimensions of noise frequency and acoustic field, and a hybrid method is recommended due to its good adaptability for noise prediction in open deck spaces, which provides the basis for the prediction process. Finally, a soundscape comfort-based design concept is proposed through an analysis of traditional noise evaluation and measurement methods, which can be used as a reference for vibration and noise control in the open deck spaces of large cruise ships.

ObjectiveThe structural response and dynamic structural collapse mode of a container ship in waves are studied by fully considering the effects of load nonlinearity and surface nonlinearity.MethodsFirst, a hydrodynamic model of a container ship is established based on the CFD platform, and the overset grid method is used to realize matching between the dynamic boundary grid of the hull hydrodynamic model and the Euler grid in the far-field fluid domain. The volume of fluid method is used to simulate the nonlinearity of the free surface in the whole fluid domain, and the N–S equations in three directions are solved in the whole flow field domain so as to solve the nonlinear wave load of the ship in real time. A nonlinear finite element model of the ship that can simulate its collapse behavior is then established, and the time-domain collapse response of the ship including plasticity and buckling is calculated based on the explicit dynamic nonlinear finite element method (FEM). Finally, the transmission of fluid pressure and node displacement between the hydrodynamic model and structural finite element model on the wet surface are realized, and two-way iterative coupling between the CFD solver and nonlinear finite element solver is carried out to calculate the nonlinear wave load and structural collapse response during the structural collapse of a 4600 TEU container ship in real time. ResultsUnder extreme waves, the upper to middle structures of the container ship are widely plastic, the main deck, side plate, deck longitudinal, side longitudinal and other components have typical yield instability under the action of wave loads, the deck longitudinal, side longitudinal and other structural members have serious lateral instability, and the hull structure loses its bearing capacity.ConclusionThe proposed CFD nonlinear FEM can accurately solve the structural response and dynamic collapse mode, making it viable as a new approach to studying the collapse response of ship structures.

ObjectivesThe structural parameters of the stiffened plate have an essential influence on its resistance to underwater explosion. It is necessary to analyze the specific influence degree of different parameters such as the stiffeners' height, number, and thickness. MethodsA series of numerical simulations were performed using the CEL method. Then, the influence of stiffened plates' structural parameters on their resistance to underwater explosion was analyzed. Based on the energy absorption law of stiffened plates underwater explosion load, a coefficient was introduced to characterize the influence degree of stiffeners. A calculation method of equivalent thickness was proposed considering stiffener coefficients. ResultsThe height of the stiffener, the panel thickness, and the stiffener's thickness have remarkable effects on the resistance to underwater explosion. In contrast, the thickness of the wing plate has an insignificant impact. Under the condition of the same amount of structural mass change, the influence of the height of the transverse/longitudinal stiffener on the damaged area of the stiffened plate is 2.5 times that of the wing panel thickness. The impact of the panel thickness and the thickness of the transverse/longitudinal stiffener on the damaged area is twice that of the wing panel thickness. With the increase of the stiffeners' height, number, and thickness, the structural strength and resistance to underwater explosion of the stiffened plate are enhanced, and the damage degree of the stiffened plate is reduced. The correlation coefficient of the proposed equivalent thickness calculation method considering the stiffener coefficient is −0.94. The method can adequately reflect the stiffened plate's resistance to underwater explosion. ConclusionsThe research results can be used as the basis for evaluating the ship structure against underwater explosion load and provide a reference for the design of the ship's anti-explosion structure.

ObjectivesThe atrium structure is an important functional cabin in the superstructure of a large cruise ship. Atriums have a large spatial span and are always subjected to complex loads. A fast and reliable safety assessment simulation method for atrium structures is required to assist in their structural design.MethodsBased on the Guidance for Direct Calculation of Local Structures of Cruise Ships 2021 by the China Classification Society (CCS) and the loading characteristics of atriums, a direct calculation design method is proposed in which loads on structures are equivalent to combined simplified loads in three groups, namely longitudinal bending, vertical shear and local cargo pressure.ResultsThe results of the proposed direct calculation design method of a specific atrium structure are in good agreement with the whole-ship finite element analytical results, verifying its effectiveness.ConclusionsThis study can provide guidance for the design process of atrium structures in large cruise ships.

The concept of “all cores are created equal” has been popular for several decades due to its simplicity and effectiveness in CPU (Central Processing Unit) design. The more cores the CPU has, the higher performance the host owns and the higher the power consumption. However, power-saving is also one of the key goals for servers in data centers and embedded devices (e.g., mobile phones). The big.LITTLE multicore architecture, which contains high-performance cores (namely big core) and power-saved cores (namely little core), has been developed by ARM (Advanced RISC Machine) and Intel to trade off performance and power efficiency. Facing the new heterogeneous computing architecture, the traditional lock algorithms, which are designed to run on homogeneous computing architecture, cannot work optimally as usual and drop into the performance issue for the difference between big core and little core. In our preliminary experiment, we observed that, in the big.LITTLE multicore architecture, all these lock algorithms exhibit sub-optimal performance. The FIFO-based (First In First Out) locks experience throughput degradation, while the performance of competition-based locks can be divided into two categories. One of them is big-core-friendly, so their tail latency increases significantly; the other is little-core-friendly. Not only does the tail latency increase, but the throughput is also degraded. Motivated by this observation, we propose a Core-Aware Lock for the big.LITTLE multicore architecture named CAL, which keeps each core having an equal opportunity to access the critical section in the program. The core idea of the CAL is to take the slowdown ratio as the matric to reorder lock requests of these big and little cores. By evaluating benchmarks and a real-world application named LevelDB, CAL is confirmed to achieve fairness goals in heterogeneous computing architecture without sacrificing the performance of the big core. Compared to several traditional lock algorithms, the CAL’s fairness has increased by up to 67%; and Its throughput is 26% higher than FIFO-based locks and 53% higher than competition-based locks, respectively. In addition, the tail latency of CAL is always kept at a low level.

With rapid urbanization, retrieving information about residential complexes in a timely manner is essential for urban planning. To develop efficiency and accuracy of building extraction in residential complexes, a Segment Anything Model-based residential building instance segmentation method with an automated prompt generator was proposed combining LiDAR data and VHR remote sensing images in this study. Three key steps are included in this method: approximate footprint detection using LiDAR data, automatic prompt generation for the SAM, and residential building footprint extraction. By applying this method, residential building footprints were extracted in Pukou District, Nanjing, Jiangsu Province. Based on this, a comprehensive assessment model was constructed to systematically evaluate the spatial layout of urban complexes using six dimensions of assessment indicators. The results showed the following: (1) The proposed method was used to effectively extract residential building footprints. (2) The residential complexes in the study area were classified into four levels. The numbers of complexes classified as Excellent, Good, Average, and Poor were 10, 29, 16, and 1, respectively. Residential complexes of different levels exhibited varying spatial layouts and building distributions. The results provide a visual representation of the spatial distribution of residential complexes that belong to different levels within the study area, aiding in urban planning.

Shot peening (SP) treatment is a common surface treatment used to enhance the mechanical properties and stress corrosion resistance of components. However, accurately measuring the mechanical properties of the thin surface deformation layer using conventional techniques is challenging. This study addresses this limitation using an in-situ X-ray diffraction (XRD) test technique in combination with a micro-tensile tester to determine the thin surface layer mechanical properties of the shot-peened Mg-8Gd-8Y (GW83) alloy. The results demonstrated that SP developed a gradient-strengthened layer with ultrafine grains near the surface layer. The minimum domain size was 51 nm using the modified Williamson–Hall method. The yield strength of the strengthened layer was 24% higher than that of the matrix material. The relaxation rule of the surface compressive residual stress (CRS) was explored under tensile–tensile cyclic loading. It was found that the CRS relaxed within five cycles and tended to be relatively stable there after. The relaxation rule was greatly affected by the initial CRS state, external stress amplitude, and cycle numbers.

ObjectivesThe afterburning effect need to be considered when TNT explodes inside a confined space. In order to accurately analyze the internal blast load, it is necessary to explore the relationship between the afterburning energy value and the charge volume ratio. MethodsThe explosion experiments of 5 different masses of TNT were performed in the confined spaces filled with air and helium. Based on three different methods of chemical reaction analysis, energy conservation law and hypothetical isentropic process, the corresponding afterburning energy of five different charge volume ratios is calculated. The numerical simulation of explosion in confined space considering afterburning effect was realized by ANSYS/AUTODYN program.ResultsThe comparison between quasi-static pressure simulation results and experimental results shows that the theoretical value of afterburning energy calculated by chemical reaction analysis method can only be used as the upper limit value, the accuracy of energy conservation method depends on the adiabatic index of mixed gas, and the error of assumed isentropic process method is stable between 4% ～ 7%. Different afterburning energy release processes do not change the final quasi-static pressure, but only the reflected shock wave pressure. ConclusionsThe research results can provide more accurate input load for the design and damage assessment of anti-explosion structures.

ObjectiveA large opening on the swimming pool structure of a large cruise ship reduces the carrying capacity of the deck structure. The opening reinforcement is an effective approach to improve the structural strength. However, various forms of reinforcements pose a challenge to the optimal design of opening structures. MethodsA variable density topology optimization method is used to optimize the opening reinforcement of a swimming pool, and a new form of opening reinforcement is obtained. Next, a size optimization method is used to obtain a more reasonable distribution of plate thicknesses, thereby achieving better weight reduction.ResultsAs the results show, compared with the prototype structure, the optimized structure has an increased ultimate bearing capacity of 1.1%, maximum stress reduction of 3.3% and weight reduction of 7.0%.ConclusionThe proposed optimization design method can provide a reinforcement approach for designing the deck opening structures of cruise ships.

The composite stiffened plate has garnered significant attention in the lightweight design of ship structures due to its superior mechanical properties. Although it reduces the structural weight, it also increases vibration sensitivity. Thus, investigating the vibration characteristics of the composite stiffened plate is crucial. This paper proposed a theoretical model based on the energy principle and the improved Fourier series method (IFSM) to analyze the composite stiffened plate vibration characteristics. The model demonstrates high reliability and accuracy, as confirmed through convergence analysis and comparison with experimental results from the published literature. Results indicate that geometry and material parameters significantly impact the natural frequency and can mitigate vibration responses by increasing thickness and stiffness. Additionally, ply design parameters markedly influence the vibration of composite stiffened plates, enhancing low-frequency vibration performance through optimal ply design. The structural parameters of the stiffeners, particularly the height and number of stiffeners, play a crucial role, enhancing stiffness and reducing the vibration responses of the composite stiffened plates.

Research has established that the incorporation of 3D-printed lattice structures in cement substrates enhances the mechanical properties of cementitious materials. However, given that 3D-printing materials, notably polymers, exhibit varying degrees of mechanical performance under high-temperature conditions, their efficacy is compromised. Notably, at temperatures reaching 150 °C, these materials soften and lose their load-bearing capacity, necessitating further investigation into their compressive mechanical behavior in such environments. This study evaluates the compressibility of cement materials reinforced with lattice structures made from polyamide 6 (PA6) across different structural configurations and ambient temperatures, employing ABAQUS for simulation. Six distinct 3D-printed lattice designs with equivalent volume but varying configurations were tested under ambient temperatures of 20 °C, 50 °C, and 100 °C to assess their impact on compressive properties. The findings indicate that heightened ambient temperatures significantly diminish the reinforcing effect of 3D-printed materials on the properties of cement-based composites.

ObjectivesThis study aims to explore nonlinear similarity criteria for box girders under pure bending load, improve the prediction accuracy of the model on the response of prototype structures and provide a theoretical basis for establishing a distortional similarity model design method for actual ship structures.MethodsFirst, based on the stability and nonlinear criteria of axially compressed reinforced slabs, a nonlinear similarity criterion for box girders under pure bending load is established using the theoretical analysis method. Second, the ultimate load-carrying capacity and buckling response of scaled-down prototype box girder models are then analyzed using the numerical calculation method to verify the validity of the similarity criterion.ResultsThe numerical calculation results show that different scale designs based on the proposed method have high similarities in their flexural failure modes, and the ultimate strength of the scaled-down prototype models can be accurately predicted. Under a specific flexural mode, an increase in the initial deformation reduces the ultimate load-carrying capacity of the box girder. In contrast, the initial deformation factor has less influence on the prediction accuracy of the scaled-down model.ConclusionsThis paper provides an effective nonlinear similarity model design method for the ultimate strength testing of hull beams under pure bending load, which has value for the study of the structural safety of ships.

ObjectivesAs composite materials have varied internal structures, an in-depth analysis of the damage mechanisms of their component materials can provide a research foundation for the ultimate strength analysis of composite stiffened panels. MethodsThe microscopic, mesoscopic and macroscopic mechanical analyses of marine glass fiber reinforced plastic (GFRP) composite stiffened panels are carried out using a multi-scale approach. Microscopic and mesoscopic representative volume element (RVE) models of chopped strand mat (CSM) and woven roving (WR) materials are established, and the macroscopic equivalent stiffness is obtained by homogenizing the RVE models. The ABAQUS VUMAT subroutine is used to code the progressive damage evolution model of the composite materials to derive the damage evolution mechanism of the microscopic and mesoscopic models respectively. The equivalent strength of macroscopic laminates is also obtained. ResultsThe multi-scale approach can be used to accurately evaluate the macroscopic mechanical properties of composite materials, and the ultimate strength of composite stiffened panels is mainly determined by fiber bundle failure. ConclusionsThe obtained macroscopic material parameters can be used to calculate the ultimate strength of composite stiffened panels, while the parametric study of the mesomechanics of composite materials can provide an analysis tool for investigating the influence of material processing technology.

The compressive residual stress field (CRSF) relaxes during the fatigue crack growth (FCG) process, and the pattern of this relaxation remains unclear. Residual stress (RS) relaxation leads to a change in residual stress intensity factor (RSIF), which significantly affects the fatigue crack growth rate (FCGR) and thus affects the assessment of fatigue crack growth rate. To this end, this work designed a series of experiments to explore the FCG behaviour in compressive residual stress fields (CRSFs) by considering RS relaxation. Firstly, shot peening(SP) treatments were conducted on the specimens. Then, residual stress fields (RSFs) at different crack propagation stages were measured to analyse the relationship between surface RS and inner RSF distribution. The derived weight function and the real-time RSF are combined to calculate the RSIF with/without considering RS relaxation. Finally, the effect of RS relaxation on the accuracy of FCGR assessment was investigated. The results show that the positive effect of CRS on the fatigue performance of the peened specimens is primarily embodied in the early stage of the FCG process. With the continuous relaxation of the CRSF, the difference in FCGR between the peened and unpeened specimens gradually decreases and tends to disappear. When the applied SIFs are large enough, the CRS would completely relax, and the inhibiting effect of CRSF on FCGR would fail. The proposed method in this work can effectively predict the FCGR of the peened specimen when considering the RS relaxation. This work could provide some meaningful insights for the assessment method of FCGR prediction in CRSF induced by surface strengthening treatment.

Low-molecular-weight polysaccharides (RLPs) extracted from Rosa laevigata fruits showed multiple biofunctions in Asia. This study aimed to investigate its anti-inflammatory obesity effect in high-fat diet-fed rats and further elucidated the underlying molecular mechanism by multi-omics methods. The results showed that RLPs administration had significantly restored immune organ indexes and reduced body weight gain. RNA-seq revealed that the effect of RLPs was partially attributed to its regulation on PPARs signaling by increasing the expressions of Scd, Acox3 and Hmgcs2, and on other redox-related pathways by decreasing the expressions of Cyp2e1, Il1-r1 and Lbp. Moreover, 16S rRNA sequencing coupled with metagenome sequencing showed that RLPs had significantly reduced the ratio of Firmicutes/Bacteroidetes from 8.01 to 2.37, and significantly increased the relative abundances of Alistipes, Prevotella, and Akkermansia from 0.36 %, 1.10 % and 2.61 % to 0.65 %, 2.37 % and 4.42 %, respectively. Spearman correlation analysis result indicated that the abundances of Lachnospiraceae, Prevotella and Bacteroidales were significantly negatively correlated with obesity phenotype, liver function and inflammatory factors. These results revealed that RLPs exerted significant anti-inflammatory obesity property partially via regulation on gut microbiota interface and the redox balance. Therefore, RLPs could be a promising functional food resource with the potential for redox imbalance-related diseases chemoprevention.

ObjectivesDuring the mission, the ship may be simultaneously subjected to the combined wave load and underwater explosion bubble pulsation load, resulting in the "superposition effect" of hull response and the loss of total strength of the ship. Therefore, it is necessary to explore the dynamic response law of hull girder under the combined action of above-mentioned loads. MethodsFirst, a simplified hull girder model is established by theoretical analysis, and the bubble pulsation load of underwater explosion and wave load are solved. Then, based on the Hamilton Principle, the differential equations of motion of hull girder at both free ends subjected to the two loads are derived separately and jointly. Finally, based on the solution of the motion differential equation, the hull girder's free vibration response and the simplified model's motion response under the three working conditions of external load combination are analyzed. ResultsThe results show that under the combined action of the two loads, the motion response of the hull girder is 15% larger than the linear superposition of the motion response of the two loads alone. ConclusionsThe research done can provide a reference for developing an algorithm to analyze the motion response of ship structures under combined loads.

The explosive growth of massive data makes shingled magnetic recording (SMR) disks a promising candidate for balancing capacity and cost. SMR disks are typically configured with a persistent buffer to reduce the read–modify–write (RMW) overhead introduced by non-sequential writes. Traditional SMR zones-based persistent buffers are subject to sequential-write constraints, and frequent cleanups cause disk performance degradation. Conventional magnetic recording (CMR) zones with in-place update capabilities enable less frequent cleanups and are gradually being used to construct persistent buffers in certain SMR disks. However, existing CMR zones-based persistent buffer designs fail to accurately capture hot blocks with long update periods and are limited by an inflexible data layout, resulting in inefficient cleanups. To address the above issues, we propose a strategy called Amphisbaena. First, a two-phase data block classification method is proposed to capture frequently updated blocks. Then, a locality-aware buffer space management scheme is developed to dynamically manage blocks with different update frequencies. Finally, a latency-sensitive garbage collection policy based on the above is designed to mitigate the impact of cleanup on user requests. Experimental results show that Amphisbaena reduces latency by an average of 29.9% and the number of RMWs by an average of 37% compared to current state-of-the-art strategies.

ObjectiveThis paper studies the coupled damage effects of a ship's structure due to the internal blast loading of a warhead. MethodsBlast tests with cased charge data are conducted to verify the effectiveness of the coupled SPH-FEM approach, and numerical calculations are then performed on real ship compartment scale model tests to analyze the coupled fragmentation and shockwave damage effects of an explosion in a confined cabin.ResultsThe results show that the fragments caused by the detonation of the warhead will first cause local damage to the cabin structure. The shockwave will exacerbate the local damage, and blasted openings will further increase the space for the propagation and diffusion of the shockwave inside the chamber, which will in turn cause damage to the adjacent structures. The simple equivalence of the warhead to a bare charge does not give a true picture of the effect of the warhead on the ship's structure, and fragmentation plays a significant role in the detonation of the warhead.ConclusionsThe results of this study show that employing the coupled SPH-FEM numerical method to calculate the coupling damage effects on a ship's structure can accurately reproduce the warhead damage pattern in tests, thereby providing support for the improved assessment of the damage of naval structures under warhead detonation.

In order to explore the relationship among quality indexes of high protein recombinant rice, 16 kinds of high protein recombinant rice were prepared by extrusion using broken rice and 16 kinds of common protein powder as raw materials. The texture properties, cooking characteristics, gelatinization degree, water solubility index, water absorption index and expansion degree of high protein recombinant rice were determined, and the comprehensive scores of different high protein recombinant rice were calculated by principal component analysis. The quality evaluation index of high protein recombinant rice was screened by stepwise regression, and the comprehensive evaluation system was constructed. The results showed that the cooking quality indexes and texture quality indexes of high protein recombinant rice prepared by different proteins were quite different. The cumulative contribution rate of the three principal components extracted by principal component analysis reached 85.148%, which were 59.4725%(X1), 17.527%(X2) and 8.149%(X3), respectively. Gumminess, dissolution of solid material, hardness, water absorption index, chewiness, cohesion, gelatinization degree, resilience and rice water absorption played a major role in the first principal component, while elasticity, expansion and iodine blue value played a major role in the second principal component. Water solubility index was an important index of the third principal component. Taking the comprehensive score of high protein recombinant rice obtained by principal component analysis as dependent variable (F value), and each index value participating in principal component analysis as independent variable, the theoretical model of comprehensive quality evaluation of high protein recombinant rice was established by stepwise regression analysis: Y=0.915Xgumminess+0.208Xgelatinization degree−0.475Xdissolution of solid material+0.436Xresilience. According to the model, the best quality of high protein recombinant rice was rice protein recombinant rice, followed by soybean protein isolate recombinant rice, having a good agreement and significant positively correlated with the comprehensive score of principal components (P

In order to find out the effect of salt concentration on fermented rape stalks, the physicochemical quality and volatile components was investigated using high performance liquid chromatography (HPLC) and headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC–MS). The results showed that there were abundant kinds of free amino acids (FAAs) in all samples, mainly presenting sweet, umami and bitter taste. Through taste activity value (TAV), His, Glu, and Ala contributed significantly to the taste of the sample. 51 volatile components were identified, of which the relative contents of ketones and alcohols were high. By the relative odor activity value (ROAV) analysis, the main components that had a great impact on the flavor were phenylacetaldehyde, β-Ionone, ethyl palmitate and furanone. Adjusting the appropriate salt concentration for fermentation could improve the comprehensive quality of fermented rape stalks and promote the development and utilization of rape products.

Although NAND (Not And) flash-based Solid-State Drive (SSD) has recently demonstrated a significant performance advantage against hard disk, it still suffers from non-negligible performance under-utilization issues as the access conflict often occurs during servicing IO requests due to the share mechanism (e.g., several chips share one channel bus, several planes share one data register inside the die). Many research works have been devoted to minimizing access conflict by redesigning IO scheduling, cache replacement, and so on. These works have achieved reasonable results; however, the potential data similarity characterization is not utilized fully in prior works to alleviate access conflict. The basic idea is that, as data duplication is common in many workloads where data with the same content from different requests could be distributed to the address with minimized access conflict (i.e., the address does not share the same channel or chip), the logic address is mapped to more than one physical address. Therefore, the data can be read out from candidate pages when the channel or chip of its original address is busy. Motivated by this idea, we propose Data Similarity aware Flash Translation Layer (DS-FTL), which mainly includes a content-aware page allocation scheme and a multi-path read scheme. The DS-FTL enables maximization of the channel-level and chip-level parallelism and avoids the read stall induced by bus-shared mechanisms. We also conducted a series of experiments on SSDsim, with the subsequent results depicting the effectiveness of our scheme. Compared with the state-of-art, our scheme reduces read latency by 35.3% on average in our workloads.

This study presents experimental and finite element investigations on the ultimate strength of the funnel structure of a large passenger ship subjected to wind pressure. An experimental test is conducted using a similar model to analyze the failure characteristics of the funnel structure. The model is designed based on similar theories to simulate the progressive collapse behavior of an actual ship’s funnel under wind load. Additionally, a simplified wind loading device is also developed to apply large wind loads. Practical insights are provided in the research to assess the opening’s influence on reducing the ultimate strength of funnel structures when suffering wind pressure. Results represent the failure initiated at the edges of the large opening, with stress concentration primarily occurring at the stiffener end, showing good agreement with the simulated results performed using the finite element method. Furthermore, the effects of different parameters on the ultimate strength of the funnel structure are discussed by using the numerical method. This analysis provides an important guide for the design of funnel structures of passenger ships with openings.

The identification of longitudinal bending moments is a critical component in the health monitoring of ship structures. This study examines the effect of the failure of measurement points on the accuracy of bending moment identification and presents a solution using an XGboost fitting method. The impact of failure point position and quantity on strain fitting accuracy and bending moment identification was investigated by performing a four-point bending experiment in typical failure scenarios. Further numerical analysis was conducted to identify potential sources of errors in the measurement process. Additionally, several XGBoost-based fitting schemes were tested under practical conditions to provide reliable fitting suggestions. The results indicated that the XGboost strain fitting method outperforms conventional methods for removing failed measurement points, resulting in improved accuracy of identification. When the most critical failure condition occurs (i.e., the deck plate measurement points and deck stiffener measurement points fail), the XGboost method can still estimate the strain at the failure points with acceptable accuracy. These results also hold in complex load scenarios. Moreover, in the practical measurement conditions, the arrangement of measuring points includes two sections that are sufficient to support the fitting of failed measurement points by using the XGboost method. The XGboost strain fitting method exhibits promising potential in strain fitting applications.

Due to the tall and large superstructures of cruise ships, the wind-induced vibration of frame structure on open decks cannot be neglected. This study investigated the wind-induced vibration of a typical frame structure on a cruise ship by using wind tunnel tests and numerical simulations. Wind tunnel tests were conducted to explore the simulation methods of the fluid–structure interaction (FSI). CFD simulations were performed to obtain the wind field data of the entire ship, which was utilized as an input for the open deck through the subdomain method. Subsequently, wind-induced vibration simulations of the guide rail frame structure on the open deck was carried out under various wind conditions. The results revealed that employing the turbulence model SST k-ω had a good agreement with the experimental data. The entire ship’s CFD results have a significant impact on the subdomain’s wind-induced vibration results. The vibration frequency of the guide rail frame structure was mainly concentrated between 0.8–10.1 Hz. The most unfavorable conditions appear at the wind attack angles of 0° and 120°. This study can provide some instructive insights for the prediction of wind-induced vibration and control of typical structures on the open decks of large cruise ships.

In order to promote the deep processing and comprehensive utilization of low-value rice and meet the market demand for nutritious instant porridge, the high protein and high dietary fiber instant porridge was specially developed by this study. In this experiment, D-optimal mixture design was used to study the effects of different proportions of broken rice, soybean protein powder, quinoa, black beans, oats and black rice on the sensory and quality of instant porridge. The results showed that the best ingredients of instant porridge were broken rice flour 50%, soybean protein flour 14%, quinoa flour 20%, oat flour 5%, black bean flour 5% and black rice flour 6%. The gelatinization degree, rehydration rate, water absorption, sensory score, protein and dietary fiber content of the instant porridge prepared by the mixture formula were 97.48%, 488.36%, 493.89%, 91.14, 15.37% and 8.42% respectively. This study provides a new way for the development of functional nutritional instant porridge, and also opens up a new way for the deep processing and comprehensive utilization of low-value rice.

Recently, the emerging technology known as Interlaced Magnetic Recording (IMR) has been receiving widespread attention from both industry and academia. IMR-based disks incorporate interlaced track layouts and energy-assisted techniques to dramatically increase areal densities. The interlaced track layout means that in-place updates to the bottom track require rewriting the adjacent top track to ensure data consistency. However, at high disk utilization, frequent track rewrites degrade disk performance. To address this problem, we propose a solution called Balloon to reduce the frequency of track rewrites. First, an adaptive write interference data placement policy is introduced, which judiciously places data on tracks with low rewrite probability to avoid unnecessary rewrites. Next, an on-demand data shuffling mechanism is designed to reduce user-requests write latency by implicitly migrating data and promptly swapping tracks with high update block coverage to the top track. Finally, a write-interference-free persistent buffer design is proposed. This design dynamically adjusts buffer admission constraints and selectively evicts data blocks to improve the cooperation between data placement and data shuffling. Evaluation results show that Balloon significantly improves the write performance of IMR-based disks at medium and high utilization compared with state-of-the-art studies.

With the burgeoning of the microelectronics industry, in order to improve the transmission speed between chips in large-scale integrated circuits to meet the demands of high integration, it is necessary for interlayer insulation materials to possess a lower dielectric constant (k). Polyimide (PI) has been widely used as interlayer insulation materials for large-scale integrated circuits, and the exploration on reducing their dielectric constant has attracted extensive attention in recent years. In this work, porous PI-based composites with a low dielectric constant are mainly reviewed. The application of porous SiO2, graphene derivatives, polyoxometalates, polyhedral oligomeric silsesquioxane and hyperbranched polysiloxane in reducing the dielectric constant of PI is emphatically introduced. The key technical problems and challenges in the current research of porous polyimide materials are summarized, and the development prospect of low k polyimide is also expounded.

ObjectivesThe perforate high web structure is a special structure widely used in the superstructures of large cruise ships. In order to establish the design method of this kind of structure, it is necessary to fully grasp the mechanical characteristics of typical perforated high web structures used in the superstructures of large cruise ships.MethodsUsing the nonlinear finite element theory and classical stiffened plate theory, an analysis is made of the influence law of initial deck defects, longitudinal girder specifications and web openings on the ultimate bearing capacity of the plate frame under longitudinal compression.ResultsThe thin plate frame is more sensitive to initial defects, and the initial deformation mode is different from that of the thick plate frame. The longitudinal girder ultimate capacity contribution is bigger and the sensitivity of longitudinal pressure limit capacity to the proportion and shape of holes is low. The locations of the collapse failure buckling zones are determined by the locations of the holes. The failure modes of perforated high web frame structures are revealed.ConclusionsThe results of the influence law of key factors such as initial deck defects, geometrical dimensions of longitudinal girders and web openings on the ultimate strength of perforated high web frame structures provide guidance for the lightweight design and safety assessment of cruise ship superstructures.

As compared with the computational fluid dynamics(CFD), the airfoil optimization based on deep learning significantly reduces the computational cost. In the airfoil optimization based on deep learning, due to the uncertainty in the neural network, the optimization results deviate from the true value. In this work, a multi-network collaborative lift-to-drag ratio prediction model is constructed based on ResNet and penalty functions. Latin supersampling is used to select four angles of attack in the range of 2°–10° with significant uncertainty to limit the prediction error. Moreover, the random drift particle swarm optimization (RDPSO) algorithm is used to control the prediction error. The experimental results show that multi-network collaboration significantly reduces the error in the optimization results. As compared with the optimization based on a single network, the maximum error of multi-network coordination in single angle of attack optimization reduces by 16.0%. Consequently, this improves the reliability of airfoil optimization based on deep learning.

The demand for larger passenger capacity and more entertainment facilities has led to the rapid growth of the cruise tourism market. The superstructure of cruise ships is designed to be plumper, with numerous decks and complex structural forms. To control the weight and the center of gravity, the bending stiffness of the superstructure is always designed to be weaker than that of the main hull, resulting in a stiffness step. Currently, there is no satisfactory method to accurately estimate the influence of the stiffness step between the main hull and superstructure on the structural response of cruise ships. In the present research, an experimental analysis is conducted to investigate the stiffness step between the main hull and superstructure of a typical cruise ship. By comparing the longitudinal stress distribution characteristics with and without the stiffness step with the theoretical results, the influence of the stiffness step on the longitudinal strength is investigated. Furthermore, the maximum stress and the bending efficiency of the superstructure are also discussed. The present research is of reference significance for the structural safety and reliability design of cruise ships.

In this paper, the tensile tests of SiCp/Al composites were carried out, and the acoustic emission (AE) method was used to monitor the damage progress. The collected signals were analyzed in time-frequency domain. The AE signals were analyzed by principal component analysis (PCA) and fuzzy clustering method (FCM) to characterize the damage mode and failure mechanism of SiCp/Al composites. Three main damage modes of SiCp/Al composites were identified by FCM clustering: SiC/Al interface debonding, Al fracture and SiC particle fracture. After the tensile test, the fracture surface was analyzed by scanning electron microscope (SEM). The results of SEM and energy spectrum analysis confirmed the results of AE. The research results of this paper provide experimental support for the design and engineering application of SiCp/Al composites.

When penetrated by a high-velocity projectile, a fluid-filled container can be severely damaged and ruptured due to the intense impact loading from Hydrodynamic Ram (HRAM), which causes a primary shock wave, and then a subsequent loading phase when a cavity evolves in the fluid. In the design of fuel tanks for aircraft, and other transport vehicles, the HRAM pressure is a major concern for the reliability of the structure. In this paper, experiments of high-velocity projectiles impacting two different types of fluid-filled containers, including an aluminium wall and a composite aluminium/rubber wall, were performed to study the mitigation effect of the rubber layer on the damage of the structure and the impact loading from Hydrodynamic Ram. A high-speed camera was employed to record the formation process of the cavity, and the shock wave pressure-time histories in the fluid were also obtained by pressure transducers. By comparing and analysing the experimental results, it is shown that the rubber layer of the composite wall container was able to reduce the reflected shock pressure and the deformation of the structure.

Chemometric tools and GC-MS were employed to detect the adulteration of camellia seed oil. In the training set, 65 samples were formulated by blending pure camellia seed oil with varying concentrations of soybean, peanut and rapeseed oil and their fatty acid contents were used in chemometric analysis. Principal Component analysis revealed the distribution patterns of samples that showed a clear stratiform agglomeration according to varying amount of camellia seed oil. Fisher Discriminant Analysis (FDA) was combined to establish the classification models and the correct classification rate of cross-validation model and original model reached 92.5% and 82.5%, respectively. To test the quality of the model, a new test set was prepared and the results showed a high accuracy of 88%. This was indicated that the developed discrimination model established by PCA plus FDA was efficient in predicting the presence of other low-price edible oils in camellia seed oils.

This study aimed to elaborate on the role of salt concentration on pickled Brassica napus leaf and stem (BLS); it also contributed to the development of low-salt and healthy Brassica napus products in the harvest period. Five sets of pickled BLS samples were prepared, and the physicochemical parameters, free amino acids (FAAs), and the volatile flavor components (VFCs) were analyzed after fermentation. Results showed that some antioxidants, FAAs, and VFCs underwent dynamic changes during fermentation. Nitrite increased with an increase in the salt concentration used for fermentation. Pickled BLS contained a wide range of FAAs; a total of 23 were detected, which might be used as a source of amino acid supplementation. The VFCs were analyzed via headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography and mass spectrometry (GC-MS). A total of 51 VFCs were tentatively identified. The contribution to flavor could be expressed by the relative odor activity value (ROAV). Salt is one of the important factors affecting the quality of vegetable fermentation. Therefore, for large-scale pickled BLS production, a key issue is to balance the low salt concentration and high fermentation quality. Under the action of salt and microorganisms, the fresh BLS fermented via dry pickling, which not only improved its FAAs and VFCs, endowed the production with a unique flavor, but also prolonged the shelf life.

Using the MRC (Miss Rate Curve) to guide cache capacity allocation is a common method in the storage system. However, optimal resource allocation is an NP-complete problem due to the cache performance cliff. Existing studies ignore this phenomenon or they use partitioning technology to eliminate it without considering the performance potential behind the cliff. This paper delves into this potential and proposes a cliff-aware cache resource allocation algorithm based on the inherent relationship between the capacity and the hit rate. Experiments show that these requests where the latency is less than 130 µs is increased by 33.3%. The proposed method obtains a significant cost reduction in DRAM and improves the hitting ratio of the cache layer.

To further improve the low-frequency broadband sound absorption capability of the underwater anechoic layer (UAL) on the surface of marine equipment, a novel sound absorption structure with cavities (NSSC) is designed by adding resonators and honeycombs to the traditional sound absorption structure with cavities (SSC). Based on the principle of shear dissipation, the original intention of the design is to allow more parts of the viscoelastic material to participate the dissipation of acoustic energy. The approximate multilayer sound absorption theoretical model based on the modified transfer matrix method is used to verify the accuracy of finite element calculations. In the frequency range of 1100 Hz–10,000 Hz, the sound absorption coefficient (α) of NSSC can reach 0.8. The effects of the presence and size of cylindrical oscillators and honeycomb structures on sound absorption are discussed in detail. The results show that expanding the effective sound absorption range of the damping area of the structure is the key to improve the wideband sound absorption effect. This design concept could guide the structural design of the UAL.

With the rise of latency-sensitive and computationally intensive applications in mobile edge computing (MEC) environments, the computation offloading strategy has been widely studied to meet the low-latency demands of these applications. However, the uncertainty of various tasks and the time-varying conditions of wireless networks make it difficult for mobile devices to make efficient decisions. The existing methods also face the problems of long-delay decisions and user data privacy disclosures. In this paper, we present the FDRT, a federated learning and deep reinforcement learning-based method with two types of agents for computation offload, to minimize the system latency. FDRT uses a multi-agent collaborative computation offloading strategy, namely, DRT. DRT divides the offloading decision into whether to compute tasks locally and whether to offload tasks to MEC servers. The designed DDQN agent considers the task information, its own resources, and the network status conditions of mobile devices, and the designed D3QN agent considers these conditions of all MEC servers in the collaborative cloud-side end MEC system; both jointly learn the optimal decision. FDRT also applies federated learning to reduce communication overhead and optimize the model training of DRT by designing a new parameter aggregation method, while protecting user data privacy. The simulation results showed that DRT effectively reduced the average task execution delay by up to 50% compared with several baselines and state-of-the-art offloading strategies. FRDT also accelerates the convergence rate of multi-agent training and reduces the training time of DRT by 61.7%.

In recent years, federated learning has been able to provide an effective solution for data privacy protection, so it has been widely used in financial, medical, and other fields. However, traditional federated learning still suffers from single-point server failure, which is a frequent issue from the centralized server for global model aggregation. Additionally, it also lacks an incentive mechanism, which leads to the insufficient contribution of local devices to global model training. In this paper, we propose a blockchain-based decentralized federated learning method, named BD-FL, to solve these problems. BD-FL combines blockchain and edge computing techniques to build a decentralized federated learning system. An incentive mechanism is introduced to motivate local devices to actively participate in federated learning model training. In order to minimize the cost of model training, BD-FL designs a preference-based stable matching algorithm to bind local devices with appropriate edge servers, which can reduce communication overhead. In addition, we propose a reputation-based practical Byzantine fault tolerance (R-PBFT) algorithm to optimize the consensus process of global model training in the blockchain. Experiment results show that BD-FL effectively reduces the model training time by up to 34.9% compared with several baseline federated learning methods. The R-PBFT algorithm can improve the training efficiency of BD-FL by 12.2%.

Operating Offshore Floating Vertical Axis Wind Turbines (OF-VAWT) have the potential to perform well in the deep-sea area. Some researchers gave performance prediction by developing simplified computing models. However, these models have imperfections in considering load and motion nonlinearity, especially in extreme environments. In this work, a numerical model is developed composed of Computational Fluid Dynamics (CFD) and Dynamic Fluid Body Interaction (DFBI) to acquire the aero-hydrodynamic load and performance of OF-VAWT in general and extreme environments. Unsteady Reynolds-Averaged Navier-Stokes (URANS), SST k-ω and Eulerian Multi-Phase (EMP) models are combined to generate a gas-liquid two-phase flow field; the Volume of Fluid (VOF) model is employed to capture free-surface and make numerical wind-wave. DFBI superposition motion technology is proposed for local motion definition and motion solution, and overset with sliding meshes is introduced to achieve the grid motion. The numerical approach is verified by the tunnel and tank experimental data from the available literature. Simulation results of general cases, such as variable wind speed, wave height and wave length, are compared to discuss the effect of environmental parameters on load and performance. Comparison shows that this straight-bladed OF-VAWT is more susceptible to wind speed. Furthermore, the aerodynamic load generated by the shut-down rotor is still significant in extreme environment, which has implications for the development of OF-VAWT controller.

Floating wind power platforms are in constant motion due to waves when deployed at sea. This motion directly affects the stability and safety of the platform. Therefore, it is very important to study the laws governing the platform’s dynamic response. In this paper, the dynamic characteristics of an offshore floating wind power platform were analysed under nine different sets of operating conditions using a numerical calculation method. Following this, a scaled 1:50 platform model was tested in a tank. Model tests were carried out with different wave conditions, and dynamic response data for the platform were measured and analysed. The hydrodynamic variation rules of floating wind power generation platform in waves were obtained. Some effective measures for maintain the stability and safety of wind power platforms are put forward that can provide a reference for dynamic stability research and the design of floating wind power platforms in the future.