To scrutinize the characteristics of wave-current loads on a bridge shuttle-shaped cap–pile foundation,a 1:125 test model was considered in a laboratory flume.The inline,transverse and vertical wave–current forces a...To scrutinize the characteristics of wave-current loads on a bridge shuttle-shaped cap–pile foundation,a 1:125 test model was considered in a laboratory flume.The inline,transverse and vertical wave–current forces acting on the shuttle-shaped cap-pile group model were measured considering both random waves and a combination of random waves with a current.The experimental results have shown that the wave-current forces can be well correlated with the wave height,the wavelength,the current velocity,the incident direction and the water level in the marine environment.An increase in the current velocity can lead to a sharp increase in the inline and transverse wave-current forces,while the vertical wave-current force decreases.Moreover,the wave-current forces are particularly strong when a combination of high tide,strong wave and strong current is considered.展开更多
Studies of wave-current interactions are vital for the safe design of structures.Regular waves in the presence of uniform,linear shear,and quadratic shear currents are explored by the High-Level Green-Naghdi model in ...Studies of wave-current interactions are vital for the safe design of structures.Regular waves in the presence of uniform,linear shear,and quadratic shear currents are explored by the High-Level Green-Naghdi model in this paper.The five-point central difference method is used for spatial discretization,and the fourth-order Adams predictor-corrector scheme is employed for marching in time.The domain-decomposition method is applied for the wave-current generation and absorption.The effects of currents on the wave profile and velocity field are examined under two conditions:the same velocity of currents at the still-water level and the constant flow volume of currents.Wave profiles and velocity fields demonstrate substantial differences in three types of currents owing to the diverse vertical distribution of current velocity and vorticity.Then,loads on small-scale vertical cylinders subjected to regular waves and three types of background currents with the same flow volume are investigated.The maximum load intensity and load fluctuation amplitude in uniform,linear shear,and quadratic shear currents increase sequentially.The stretched superposition method overestimates the maximum load intensity and load fluctuation amplitude in opposing currents and underestimates these values in following currents.The stretched superposition method obtains a poor approximation for strong nonlinear waves,particularly in the case of the opposing quadratic shear current.展开更多
This study establishes and validates a method for the precise quantification of aquatic microbial loads using microbial diversity absolute quantitative sequencing.By adding synthetic spike-in DNA to water samples from...This study establishes and validates a method for the precise quantification of aquatic microbial loads using microbial diversity absolute quantitative sequencing.By adding synthetic spike-in DNA to water samples from the Dahei River prior to DNA extraction and 16S rRNA gene sequencing,it generates standard curves to convert sequencing data into absolute microbial copy numbers.The method,which is proved highly accurate(R^(2)>0.99),reveals a clear contrast between the river sites:the upstream community has not only a significantly higher total microbial load but also a completely different makeup of species compared to the downstream site.This approach effectively overcomes the limitations of relative abundance analysis,providing a powerful tool for environmental monitoring,and proposes key steps for future standardization to ensure data comparability and integration.展开更多
Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common c...Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common collision or impact methods.A moving load can generate flexural-gravity waves(FGWs),under the influence of which the ice sheet undergoes deformation and may even experience structural damage.Moving loads can be divided into above-ice loads and underwater loads.For the above-ice loads,we discuss the characteristics of the FGWs generated by a moving load acting on a complete ice sheet,an ice sheet with a crack,and an ice sheet with a lead of open water.For underwater loads,we discuss the influence on the ice-breaking characteristics of FGWs of the mode of motion,the geometrical features,and the trajectory of motion of the load.In addition to discussing the status of current research and the technical challenges of ice-breaking by moving loads,this paper also looks ahead to future research prospects and presents some preliminary ideas for consideration.展开更多
Pile foundations have been widely used in offshore engineering.In this study,a three-dimensional numerical model was used to investigate the seabed response around a mono-pile under wave-current loading.Reynolds-avera...Pile foundations have been widely used in offshore engineering.In this study,a three-dimensional numerical model was used to investigate the seabed response around a mono-pile under wave-current loading.Reynolds-averaged Navier-Stokes equations were used to simulate the flow field,and Biot's consolidation equations were used for simulating the response of a porous seabed.The pore water pressure within soil and the effective stress along the depth of the seabed were simulated for various current velocities,with currents traveling either along or against the wave.Results indicate that the current has a significant effect on the effective stress and the pore water pressure distributions,which increases with the current velocity,and that the current traveling against the wave increases the liquefaction depth of the porous seabed.展开更多
Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experi...Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation.Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed.Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter.Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.展开更多
Accurate and efficient prediction of the distribution of surface loads on buildings subjected to explosive effects is crucial for rapidly calculating structural dynamic responses,establishing effective protective meas...Accurate and efficient prediction of the distribution of surface loads on buildings subjected to explosive effects is crucial for rapidly calculating structural dynamic responses,establishing effective protective measures,and designing civil defense engineering solutions.Current state-of-the-art methods face several issues:Experimental research is difficult and costly to implement,theoretical research is limited to simple geometries and lacks precision,and direct simulations require substantial computational resources.To address these challenges,this paper presents a data-driven method for predicting blast loads on building surfaces.This approach increases both the accuracy and computational efficiency of load predictions when the geometry of the building changes while the explosive yield remains constant,significantly improving its applicability in complex scenarios.This study introduces an innovative encoder-decoder graph neural network model named BlastGraphNet,which uses a message-passing mechanism to predict the overpressure and impulse load distributions on buildings with conventional and complex geometries during explosive events.The model also facilitates related downstream applications,such as damage mode identification and rapid assessment of virtual city explosions.The calculation results indicate that the prediction error of the model for conventional building tests is less than 2%,and its inference speed is 3-4 orders of magnitude faster than that of state-of-the-art numerical methods.In extreme test cases involving buildings with complex geometries and building clusters,the method achieved high accuracy and excellent generalizability.The strong adaptability and generalizability of BlastGraphNet confirm that this novel method enables precise real-time prediction of blast loads and provides a new paradigm for damage assessment in protective engineering.展开更多
To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based sim...To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based simulation(NNS)method with higher accuracy and better efficiency was proposed.The NNS method consisted of three main steps.First,the parameters of blast loads,including the peak pressures and impulses of cylindrical charges with different aspect ratios(L/D)at different stand-off distances and incident angles were obtained by two-dimensional numerical simulations.Subsequently,incident shape factors of cylindrical charges with arbitrary aspect ratios were predicted by a neural network.Finally,reflected shape factors were derived and implemented into the subroutine of the ABAQUS code to modify the CONWEP model,including modifications of impulse and overpressure.The reliability of the proposed NNS method was verified by related experimental results.Remarkable accuracy improvement was acquired by the proposed NNS method compared with the unmodified CONWEP model.Moreover,huge efficiency superiority was obtained by the proposed NNS method compared with the CEL method.The proposed NNS method showed good accuracy when the scaled distance was greater than 0.2 m/kg^(1/3).It should be noted that there is no need to generate a new dataset again since the blast loads satisfy the similarity law,and the proposed NNS method can be directly used to simulate the blast loads generated by different cylindrical charges.The proposed NNS method with high efficiency and accuracy can be used as an effective method to analyze the dynamic response of structures under blast loads,and it has significant application prospects in designing protective structures.展开更多
In rock engineering,the cyclic shear characteristics of rough joints under dynamic disturbances are still insufficiently studied.This study conducted cyclic shear experiments on rough joints under dynamic normal loads...In rock engineering,the cyclic shear characteristics of rough joints under dynamic disturbances are still insufficiently studied.This study conducted cyclic shear experiments on rough joints under dynamic normal loads to assess the impact of shear frequency(f_(h))and shear displacement amplitude(u_(d))on the frictional properties of the joint.The results reveal that within a single shearing cycle,the normal displacement negatively correlates with the dynamic normal force.As the shear cycle number increases,the joint surface undergoes progressive wear,resulting in an exponential decrease in the peak normal displacement.In the cyclic shearing procedure,the forward peak values of shear force and friction coefficient display larger fluctuations at either lower or higher shear frequencies.However,under moderate shear frequency conditions,the changes in the shear strength of the joint surface are smaller,and the degree of degradation post-shearing is relatively limited.As the shear displacement amplitude increases,the range of normal deformation within the joint widens.Furthermore,after shearing,the corresponding joint roughness coefficient trend shows a gradual decrease with an increasing shear displacement amplitude,while varying with the shearing frequency in a pattern that initially rises and then falls,with a turning point at 0.05 Hz.The findings of this research contribute to a profound comprehension of the cyclic frictional properties of rock joints under dynamic disturbances.展开更多
Imbalanced loads in freight railway vehicles pose significant risks to vehicle running safety as well as track integrity,increasing the likelihood of derailments and increasing track wear rate.This study presents a ro...Imbalanced loads in freight railway vehicles pose significant risks to vehicle running safety as well as track integrity,increasing the likelihood of derailments and increasing track wear rate.This study presents a robust machine learning-based methodology designed to detect and classify transverse imbalances in freight vehicles using dynamic rail responses.The proposed approach employs wayside monitoring systems with accelerometers and strain gauges,integrating advanced feature extraction methods,including principal component analysis,log-mel spectrograms,and multi-feature-based techniques.The methodology enhances detection accuracy by normalizing features to eliminate environmental and operational variations and employing data fusion for sensitive index creation.It is capable of distinguishing between different severity levels of imbalanced loads across various wagon types.By simulating scenarios with typical European freight wagons,the study demonstrates the effectiveness of the approach,offering a valuable tool for railway infrastructure managers to mitigate risks associated with imbalanced loads.This research contributes to the field by providing a scalable,non-invasive solution for real-time monitoring and safety enhancement in freight rail operations.展开更多
This paper establishes a method for identifying and locating dynamic loads in time-varying systems.The proposed method linearizes time-varying parameters within small time units and uses the Wilson-θ inverse analysis...This paper establishes a method for identifying and locating dynamic loads in time-varying systems.The proposed method linearizes time-varying parameters within small time units and uses the Wilson-θ inverse analysis method to solve modal loads of each order at each time step.It then uses an exhaustive method to determine the load position.Finally,it calculates the time history of the load.Simulation examples demonstrate how the number of measuring points and step size affect load identi-fication accuracy,verifying that this algorithm achieves good identification accuracy for loads under resonance conditions.Additionally,it explores how noise affects load position and recognition accuracy,while providing a solution.Simulation examples and experimental results demonstrate that the proposed method can identify both the time history and position of loads simultaneously with high identification accuracy.展开更多
Current fatigue damage analysis of various components(e.g.aircraft parts)focuses on effects of High-Cycle-Fatigue(HCF)loads while overlooking effects of Very-High-Cycle-Fatigue(VHCF)loads,thereby introducing a substan...Current fatigue damage analysis of various components(e.g.aircraft parts)focuses on effects of High-Cycle-Fatigue(HCF)loads while overlooking effects of Very-High-Cycle-Fatigue(VHCF)loads,thereby introducing a substantial bias.The crux of decreasing this bias lies in how to reasonably consider the threshold effect and nonlinear effect of VHCF loads'fatigue damage evolution.This problem is addressed in this paper from the perspective of Residual Fatigue Quality(RFQ,represent residual S-N^(*)curve and residual fatigue limitσ_(-1)^(*)).Fatigue tests were conducted on AA2024-T4 under various constant/variable-amplitude loads to reveal the evolution characteristics of RFQ and measure the equivalent fatigue damage of VHCF loads block loaded with various number of pre-loading HCF loads.Corresponding mechanisms were analysed in view of evolution of extrusions/intrusions along persistent slip bands.Theoretical analysis was conducted to reveal the relationship between RFQ and fatigue damage of VHCF loads block.Based on the above results,an isodamage curve-based fatigue damage analysis method was proposed,where bilinear-isodamage curves(consist of S-N^(*)curves intersecting at a point and corresponding_(σ-1)^(*))were adopted to consider the RFQ degeneration and its effect.This method reduces analysis bias to 1/3 of previous methods for typical variable-amplitude loads in HCF and HCF-VHCF regime.展开更多
Through-silicon via(TSV)is an important technique in three-dimension integration.The mechanical performance of TSV-Cu is critical to the electrical performance and signal transmission.In this work,the deformation of s...Through-silicon via(TSV)is an important technique in three-dimension integration.The mechanical performance of TSV-Cu is critical to the electrical performance and signal transmission.In this work,the deformation of single-crystalline TSV-Cu during annealing process was studied using molecular dynamics method.The protrusion morphology and protrusion height of Cu column were revealed.The protrusion height curves can be divided into four stages:slow increase,fast increase,fast decrease,and saturation.During the deformation process,the main deformation mode is temporary amorphous region followed by residual dislocations.The influences of annealing temperatures,heating rates,and column sizes on protrusion height were studied.Results show that the residual protrusion height increases with increasing annealing temperatures and decreasing heating rates.The residual protrusion height increases with increasing column sizes in terms of column diameter and length.This work provides new insights into understanding the mechanical performance of nano-TSV-Cu.展开更多
In order to more accurately calculate the fatigue damage and fatigue life of steel-concrete composite beam under standard vehicle load,the steel beam components of a large-span steel-concrete composite beam suspension...In order to more accurately calculate the fatigue damage and fatigue life of steel-concrete composite beam under standard vehicle load,the steel beam components of a large-span steel-concrete composite beam suspension bridge were taken as the research object.Based on the S-N curve and linear fatigue damage theory,a standard segment model was established.Accordingly,the welding position of the secondary longitudinal beam was identified as the focus fatigue point,and the stress time course calculation was done for the point.The results showed that when the vehicle mass increases from 50 t to 100 t,the amount of fatigue damage will increase by more than 5 times in the same period of time,and the increase in the vehicle mass will reduce the fatigue life of the bridge structure.The fatigue damage of bridge structures increases with the increase of vehicle speed.The increase rate of fatigue damage is greater at low speeds,and the increase rate of fatigue damage slows down at high speeds.展开更多
Increasing interest has been directed toward the potential of heterogeneous flexible loads to mitigate the challenges associated with the increasing variability and uncertainty of renewable generation.Evaluating the a...Increasing interest has been directed toward the potential of heterogeneous flexible loads to mitigate the challenges associated with the increasing variability and uncertainty of renewable generation.Evaluating the aggregated flexible region of load clusters managed by load aggregators is the crucial basis of power system scheduling for the system operator.This is because the aggregation result affects the qual-ity of the scheduling schemes.A stringent computation based on the Minkowski sum is NP-hard,whereas existing approximation meth-ods that use a special type of polytope exhibit limited adaptability when aggregating heterogeneous loads.This study proposes a stringent internal approximation method based on the convex hull of multiple layers of maximum volume boxes and embeds it into a day-ahead scheduling optimization model.The numerical results indicate that the aggregation accuracy can be improved compared with methods based on one type of special polytope,including boxes,zonotopes,and homothets.Hence,the reliability and economy of the power sys-tem scheduling can be enhanced.展开更多
Offshore floating photovoltaic systems have tremendous potential to address the energy crisis.As a novel type of float-ing photovoltaic system,membrane structures are increasingly applied due to their advantages of be...Offshore floating photovoltaic systems have tremendous potential to address the energy crisis.As a novel type of float-ing photovoltaic system,membrane structures are increasingly applied due to their advantages of being lightweight and cost-effective.A 1:40 scaled model for laboratory experiments was designed and developed,considering Ocean Sun’s membrane structure.The study aims to investigate the hydrodynamic characteristics of the membrane structure under wave loading by testing its various mo-tion responses and mooring forces at different wave heights and periods.The conclusions indicate that as the wave period decreases within the range of 1.75 to 1.25 s,the heave motion response of the structure decreases,whereas pitch,surge motion response,heave acceleration,and mooring force increase.The amplitudes of various motions and mooring forces of the structure decrease with de-creasing wave height.The hydrodynamic responses under irregular and regular waves follow similar patterns,but the responses and mooring forces induced by irregular waves are more significant.The structure should be designed based on the actual wave height.In addition,the same frequency resonance phenomenon is avoided because the movement period of each degree of freedom is close to the wave period.展开更多
A multi-resolution smoothed particle hydrodynamics and peridynamics(SPH-PD)coupling model is proposed in this study for simulating the fracture characteristics of ice plates exposed to underwater blast loads.The SPH m...A multi-resolution smoothed particle hydrodynamics and peridynamics(SPH-PD)coupling model is proposed in this study for simulating the fracture characteristics of ice plates exposed to underwater blast loads.The SPH model employs a volume adaptive scheme(VAS)and a multi-resolution particle technique to accurately simulate explosive charge detonation and shock wave propagation.This approach addresses numerical challenges from charge expansion and significant size disparity between the charge and the fluid particles.The model captures the full underwater explosion process,covering both the shock wave phase and the bubble expansion stage,by applying appropriate equations of state for each respective phase.To analyze ice plate damage and crack propagation influenced by temperature changes,an ordinary state-based PD(OSB-PD)formulation with coupled mechanical and thermodynamic models is used.Numerical results show that the proposed coupling method demonstrates good agreement with reference solutions and experimental data.展开更多
The growing utilization of the ocean as a renewable energy source drives the need for reliable maritime infrastructure.One major challenge for these structures is withstanding impulsive loads from extreme ocean waves,...The growing utilization of the ocean as a renewable energy source drives the need for reliable maritime infrastructure.One major challenge for these structures is withstanding impulsive loads from extreme ocean waves,which requires materials with high strength and deformation resistance to maintain structural integrity.Metal Matrix Composite(MMC)is a promising material,yet studies on its behavior under impulsive loading remain limited.This study investigates the ultimate capacity of MMC sandwich structures using the Finite Element Method(FEM)through simulations with an Underwater Shock Loading Simulator(USLS).Validation against the results of He et al.confirms the accuracy of the simulation method.Results indicate that increasing flyer velocity from 135 to 195 m/s raises the maximum displacement from 5.83 mm to 10.7 mm.Increasing face sheet thickness from 0.4 to 1.8 mm reduces deformation from 4.95 to 3.09 mm,while increasing core thickness from 14 to 20 mm decreases deflection from 5.42 to 3.68 mm.Furthermore,the thickness ratio analysis indicates that the 1:10 configuration produces the smallest deformation(4.13 mm)and is more efficient because it provides higher stiffness with lower mass.These findings demonstrate that optimizing core and face sheet thickness significantly enhances structural resistance to deformation.The study concludes that a balanced thickness configuration is key to improving the structural performance of MMC sandwiches,supporting the design of stronger and more sustainable materials for maritime structures in extreme environments.展开更多
This paper introduces a thermodynamically grounded framework that replaces conventional energy-centric building simulation with a heat-based reconstruction method,enabling the use of standard-year weather data without...This paper introduces a thermodynamically grounded framework that replaces conventional energy-centric building simulation with a heat-based reconstruction method,enabling the use of standard-year weather data without bespoke weather files.High-accuracy predictive models are developed to estimate seasonal heating and cooling loads and to derive convective heat transfer coefficients for transitional seasons.Models are calibrated against extended AMeDAS records for Kurume,Fukuoka Prefecture,demonstrating improved capture of local climatic variability compared with standard practice.Methodologically,the study establishes time-series regression relationships linking outdoor air temperature,incident solar radiation,and wind speed to instantaneous thermal demand and surface convective rates.These empirical relations feed a reconstruction algorithm that adjusts simulation outputs to standardized climatic conditions by rescaling heat flows and convective parameters rather than altering meteorological inputs.Results indicate that reframing simulation inputs in terms of heat enhances reliability and transferability of performance predictions and reduces uncertainty associated with variable weather.The paper examines essential assumptions affecting applicability,including the assumed linearity of convective correlations,representativeness of the reference building envelope,and the use of virtual walls for parameter identification.It further proposes a novel procedure to compute a physical adjustment coefficient for the convective heat transfer coefficient,addressing a parameter gap in macro-scale models while acknowledging challenges for conventional comparative validation.The authors recommend future work on automated calibration routines and on extending the method to tropical and arid climates to broaden applicability and support foundational reform of building energy simulation.展开更多
The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial...The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial nonlinear energy sink(NES)is applied for the first time to achieve vibration suppression in beams under moving loads.Based on the Timoshenko beam theory,the nonlinear motion equations of a beam with an inertial NES are derived using the energy method and Lagrange equations.The Newmark-βmethod combined with the Heaviside step function is adopted to calculate the responses of the beam under moving loads of constant amplitude and harmonic excitation.The accuracy of the modelling derivation and solution methodology are validated through comparisons with results from other studies.The results demonstrate that the velocity and excitation frequency of the moving load significantly affect the response of the beam as well as the performance of the inertial NES.To enhance its effectiveness under various moving load conditions,parametric optimization is numerically performed.The optimized inertial NES can achieve good performance by efficiently reducing the maximum deflection of the beam.The findings of this study contribute to advancing the understanding and application of NESs in mitigating structural vibrations caused by moving loads.展开更多
基金supported by the Major Special Science and Technology Project of“Ningbo Science and Technology Innovation 2025”(Grant No.2019B10076)Natural Science Foundation of Zhejiang Province(No.LY23E080001).
文摘To scrutinize the characteristics of wave-current loads on a bridge shuttle-shaped cap–pile foundation,a 1:125 test model was considered in a laboratory flume.The inline,transverse and vertical wave–current forces acting on the shuttle-shaped cap-pile group model were measured considering both random waves and a combination of random waves with a current.The experimental results have shown that the wave-current forces can be well correlated with the wave height,the wavelength,the current velocity,the incident direction and the water level in the marine environment.An increase in the current velocity can lead to a sharp increase in the inline and transverse wave-current forces,while the vertical wave-current force decreases.Moreover,the wave-current forces are particularly strong when a combination of high tide,strong wave and strong current is considered.
基金Supported by the Development and Application Project of Ship CAE Software.
文摘Studies of wave-current interactions are vital for the safe design of structures.Regular waves in the presence of uniform,linear shear,and quadratic shear currents are explored by the High-Level Green-Naghdi model in this paper.The five-point central difference method is used for spatial discretization,and the fourth-order Adams predictor-corrector scheme is employed for marching in time.The domain-decomposition method is applied for the wave-current generation and absorption.The effects of currents on the wave profile and velocity field are examined under two conditions:the same velocity of currents at the still-water level and the constant flow volume of currents.Wave profiles and velocity fields demonstrate substantial differences in three types of currents owing to the diverse vertical distribution of current velocity and vorticity.Then,loads on small-scale vertical cylinders subjected to regular waves and three types of background currents with the same flow volume are investigated.The maximum load intensity and load fluctuation amplitude in uniform,linear shear,and quadratic shear currents increase sequentially.The stretched superposition method overestimates the maximum load intensity and load fluctuation amplitude in opposing currents and underestimates these values in following currents.The stretched superposition method obtains a poor approximation for strong nonlinear waves,particularly in the case of the opposing quadratic shear current.
基金supported by the National Natural Science Foundation of China(Grant No.32160172)the Key Science-Technology Project of Inner Mongolia(2023KYPT0010)+1 种基金the Natural Science Foundation of Inner Mongolia Autonomous Region of China(Grant No.2025QN03006)the 2023 Inner Mongolia Public Institution High-level Talent Introduction Scientific Research Support Project.
文摘This study establishes and validates a method for the precise quantification of aquatic microbial loads using microbial diversity absolute quantitative sequencing.By adding synthetic spike-in DNA to water samples from the Dahei River prior to DNA extraction and 16S rRNA gene sequencing,it generates standard curves to convert sequencing data into absolute microbial copy numbers.The method,which is proved highly accurate(R^(2)>0.99),reveals a clear contrast between the river sites:the upstream community has not only a significantly higher total microbial load but also a completely different makeup of species compared to the downstream site.This approach effectively overcomes the limitations of relative abundance analysis,providing a powerful tool for environmental monitoring,and proposes key steps for future standardization to ensure data comparability and integration.
基金Supported by the National Natural Science Foundation of China(Nos.52192693,52192690,52371270,U20A20327)the National Key Research and Development Program of China(Nos.2021YFC2803400).
文摘Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common collision or impact methods.A moving load can generate flexural-gravity waves(FGWs),under the influence of which the ice sheet undergoes deformation and may even experience structural damage.Moving loads can be divided into above-ice loads and underwater loads.For the above-ice loads,we discuss the characteristics of the FGWs generated by a moving load acting on a complete ice sheet,an ice sheet with a crack,and an ice sheet with a lead of open water.For underwater loads,we discuss the influence on the ice-breaking characteristics of FGWs of the mode of motion,the geometrical features,and the trajectory of motion of the load.In addition to discussing the status of current research and the technical challenges of ice-breaking by moving loads,this paper also looks ahead to future research prospects and presents some preliminary ideas for consideration.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC1404200)the National Natural Science Foundation of China(Grant No.51479053)the Marine Renewable Energy Research Project of the State Oceanic Administration(Grant No.GHME2015GC01).
文摘Pile foundations have been widely used in offshore engineering.In this study,a three-dimensional numerical model was used to investigate the seabed response around a mono-pile under wave-current loading.Reynolds-averaged Navier-Stokes equations were used to simulate the flow field,and Biot's consolidation equations were used for simulating the response of a porous seabed.The pore water pressure within soil and the effective stress along the depth of the seabed were simulated for various current velocities,with currents traveling either along or against the wave.Results indicate that the current has a significant effect on the effective stress and the pore water pressure distributions,which increases with the current velocity,and that the current traveling against the wave increases the liquefaction depth of the porous seabed.
基金financially supported by the National Key Research and Development Program of China (Grant No. 2021YFB2601100)the National Natural Science Foundation of China (Grant No. 51979190)。
文摘Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation.Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed.Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter.Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.
基金supported by the National Natural Science Founion of China(U2241285).
文摘Accurate and efficient prediction of the distribution of surface loads on buildings subjected to explosive effects is crucial for rapidly calculating structural dynamic responses,establishing effective protective measures,and designing civil defense engineering solutions.Current state-of-the-art methods face several issues:Experimental research is difficult and costly to implement,theoretical research is limited to simple geometries and lacks precision,and direct simulations require substantial computational resources.To address these challenges,this paper presents a data-driven method for predicting blast loads on building surfaces.This approach increases both the accuracy and computational efficiency of load predictions when the geometry of the building changes while the explosive yield remains constant,significantly improving its applicability in complex scenarios.This study introduces an innovative encoder-decoder graph neural network model named BlastGraphNet,which uses a message-passing mechanism to predict the overpressure and impulse load distributions on buildings with conventional and complex geometries during explosive events.The model also facilitates related downstream applications,such as damage mode identification and rapid assessment of virtual city explosions.The calculation results indicate that the prediction error of the model for conventional building tests is less than 2%,and its inference speed is 3-4 orders of magnitude faster than that of state-of-the-art numerical methods.In extreme test cases involving buildings with complex geometries and building clusters,the method achieved high accuracy and excellent generalizability.The strong adaptability and generalizability of BlastGraphNet confirm that this novel method enables precise real-time prediction of blast loads and provides a new paradigm for damage assessment in protective engineering.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52271317 and 52071149)the Fundamental Research Funds for the Central Universities(HUST:2019kfy XJJS007)。
文摘To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based simulation(NNS)method with higher accuracy and better efficiency was proposed.The NNS method consisted of three main steps.First,the parameters of blast loads,including the peak pressures and impulses of cylindrical charges with different aspect ratios(L/D)at different stand-off distances and incident angles were obtained by two-dimensional numerical simulations.Subsequently,incident shape factors of cylindrical charges with arbitrary aspect ratios were predicted by a neural network.Finally,reflected shape factors were derived and implemented into the subroutine of the ABAQUS code to modify the CONWEP model,including modifications of impulse and overpressure.The reliability of the proposed NNS method was verified by related experimental results.Remarkable accuracy improvement was acquired by the proposed NNS method compared with the unmodified CONWEP model.Moreover,huge efficiency superiority was obtained by the proposed NNS method compared with the CEL method.The proposed NNS method showed good accuracy when the scaled distance was greater than 0.2 m/kg^(1/3).It should be noted that there is no need to generate a new dataset again since the blast loads satisfy the similarity law,and the proposed NNS method can be directly used to simulate the blast loads generated by different cylindrical charges.The proposed NNS method with high efficiency and accuracy can be used as an effective method to analyze the dynamic response of structures under blast loads,and it has significant application prospects in designing protective structures.
基金funding support from the National Natural Science Foundation of China(Grant Nos.52174092 and 51904290)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20220157).
文摘In rock engineering,the cyclic shear characteristics of rough joints under dynamic disturbances are still insufficiently studied.This study conducted cyclic shear experiments on rough joints under dynamic normal loads to assess the impact of shear frequency(f_(h))and shear displacement amplitude(u_(d))on the frictional properties of the joint.The results reveal that within a single shearing cycle,the normal displacement negatively correlates with the dynamic normal force.As the shear cycle number increases,the joint surface undergoes progressive wear,resulting in an exponential decrease in the peak normal displacement.In the cyclic shearing procedure,the forward peak values of shear force and friction coefficient display larger fluctuations at either lower or higher shear frequencies.However,under moderate shear frequency conditions,the changes in the shear strength of the joint surface are smaller,and the degree of degradation post-shearing is relatively limited.As the shear displacement amplitude increases,the range of normal deformation within the joint widens.Furthermore,after shearing,the corresponding joint roughness coefficient trend shows a gradual decrease with an increasing shear displacement amplitude,while varying with the shearing frequency in a pattern that initially rises and then falls,with a turning point at 0.05 Hz.The findings of this research contribute to a profound comprehension of the cyclic frictional properties of rock joints under dynamic disturbances.
基金CNPq (Brazilian Ministry of Science and Technology Agency), CAPES (Higher Education Improvement Agency), FAPESP (São Paulo Research Foundation) for financial support under grant #2022/130451, VALE Catedra Under Railfinancially supported by Base Funding-UIDB/04708/2020 with https://doi.org/https://doi.org/10.54499/UIDB/04708/2020 and Programmatic Funding-UIDP/04708/2020 with https://doi. org/https://doi.org/10.54499/UIDP/04708/2020 of the CONSTRUCT-Instituto de I&D em Estruturas e Construções-funded by national funds through the FCT/MCTES (PIDDAC)
文摘Imbalanced loads in freight railway vehicles pose significant risks to vehicle running safety as well as track integrity,increasing the likelihood of derailments and increasing track wear rate.This study presents a robust machine learning-based methodology designed to detect and classify transverse imbalances in freight vehicles using dynamic rail responses.The proposed approach employs wayside monitoring systems with accelerometers and strain gauges,integrating advanced feature extraction methods,including principal component analysis,log-mel spectrograms,and multi-feature-based techniques.The methodology enhances detection accuracy by normalizing features to eliminate environmental and operational variations and employing data fusion for sensitive index creation.It is capable of distinguishing between different severity levels of imbalanced loads across various wagon types.By simulating scenarios with typical European freight wagons,the study demonstrates the effectiveness of the approach,offering a valuable tool for railway infrastructure managers to mitigate risks associated with imbalanced loads.This research contributes to the field by providing a scalable,non-invasive solution for real-time monitoring and safety enhancement in freight rail operations.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘This paper establishes a method for identifying and locating dynamic loads in time-varying systems.The proposed method linearizes time-varying parameters within small time units and uses the Wilson-θ inverse analysis method to solve modal loads of each order at each time step.It then uses an exhaustive method to determine the load position.Finally,it calculates the time history of the load.Simulation examples demonstrate how the number of measuring points and step size affect load identi-fication accuracy,verifying that this algorithm achieves good identification accuracy for loads under resonance conditions.Additionally,it explores how noise affects load position and recognition accuracy,while providing a solution.Simulation examples and experimental results demonstrate that the proposed method can identify both the time history and position of loads simultaneously with high identification accuracy.
基金the support from National Key Laboratory of Strength and Structural Integrity independent research project“Failure law and fatigue life prediction method of Metal Materials based on Material property degradation”。
文摘Current fatigue damage analysis of various components(e.g.aircraft parts)focuses on effects of High-Cycle-Fatigue(HCF)loads while overlooking effects of Very-High-Cycle-Fatigue(VHCF)loads,thereby introducing a substantial bias.The crux of decreasing this bias lies in how to reasonably consider the threshold effect and nonlinear effect of VHCF loads'fatigue damage evolution.This problem is addressed in this paper from the perspective of Residual Fatigue Quality(RFQ,represent residual S-N^(*)curve and residual fatigue limitσ_(-1)^(*)).Fatigue tests were conducted on AA2024-T4 under various constant/variable-amplitude loads to reveal the evolution characteristics of RFQ and measure the equivalent fatigue damage of VHCF loads block loaded with various number of pre-loading HCF loads.Corresponding mechanisms were analysed in view of evolution of extrusions/intrusions along persistent slip bands.Theoretical analysis was conducted to reveal the relationship between RFQ and fatigue damage of VHCF loads block.Based on the above results,an isodamage curve-based fatigue damage analysis method was proposed,where bilinear-isodamage curves(consist of S-N^(*)curves intersecting at a point and corresponding_(σ-1)^(*))were adopted to consider the RFQ degeneration and its effect.This method reduces analysis bias to 1/3 of previous methods for typical variable-amplitude loads in HCF and HCF-VHCF regime.
基金financially supported by the National Natural Science Foundation of China(12232008 and 12072211)the Foundation of Key laboratory(2022JCJQLB05703)the Sichuan Province Science and Technology Project(2023NSFSC0914).
文摘Through-silicon via(TSV)is an important technique in three-dimension integration.The mechanical performance of TSV-Cu is critical to the electrical performance and signal transmission.In this work,the deformation of single-crystalline TSV-Cu during annealing process was studied using molecular dynamics method.The protrusion morphology and protrusion height of Cu column were revealed.The protrusion height curves can be divided into four stages:slow increase,fast increase,fast decrease,and saturation.During the deformation process,the main deformation mode is temporary amorphous region followed by residual dislocations.The influences of annealing temperatures,heating rates,and column sizes on protrusion height were studied.Results show that the residual protrusion height increases with increasing annealing temperatures and decreasing heating rates.The residual protrusion height increases with increasing column sizes in terms of column diameter and length.This work provides new insights into understanding the mechanical performance of nano-TSV-Cu.
文摘In order to more accurately calculate the fatigue damage and fatigue life of steel-concrete composite beam under standard vehicle load,the steel beam components of a large-span steel-concrete composite beam suspension bridge were taken as the research object.Based on the S-N curve and linear fatigue damage theory,a standard segment model was established.Accordingly,the welding position of the secondary longitudinal beam was identified as the focus fatigue point,and the stress time course calculation was done for the point.The results showed that when the vehicle mass increases from 50 t to 100 t,the amount of fatigue damage will increase by more than 5 times in the same period of time,and the increase in the vehicle mass will reduce the fatigue life of the bridge structure.The fatigue damage of bridge structures increases with the increase of vehicle speed.The increase rate of fatigue damage is greater at low speeds,and the increase rate of fatigue damage slows down at high speeds.
基金supported by State Grid science and technology projects“Research on energy and power sup-ply and demand interactive simulation technology for new power system(5100-202257028A-1-1-ZN)”.
文摘Increasing interest has been directed toward the potential of heterogeneous flexible loads to mitigate the challenges associated with the increasing variability and uncertainty of renewable generation.Evaluating the aggregated flexible region of load clusters managed by load aggregators is the crucial basis of power system scheduling for the system operator.This is because the aggregation result affects the qual-ity of the scheduling schemes.A stringent computation based on the Minkowski sum is NP-hard,whereas existing approximation meth-ods that use a special type of polytope exhibit limited adaptability when aggregating heterogeneous loads.This study proposes a stringent internal approximation method based on the convex hull of multiple layers of maximum volume boxes and embeds it into a day-ahead scheduling optimization model.The numerical results indicate that the aggregation accuracy can be improved compared with methods based on one type of special polytope,including boxes,zonotopes,and homothets.Hence,the reliability and economy of the power sys-tem scheduling can be enhanced.
基金supported by the National Natural Science Foundation of China(No.52271287).
文摘Offshore floating photovoltaic systems have tremendous potential to address the energy crisis.As a novel type of float-ing photovoltaic system,membrane structures are increasingly applied due to their advantages of being lightweight and cost-effective.A 1:40 scaled model for laboratory experiments was designed and developed,considering Ocean Sun’s membrane structure.The study aims to investigate the hydrodynamic characteristics of the membrane structure under wave loading by testing its various mo-tion responses and mooring forces at different wave heights and periods.The conclusions indicate that as the wave period decreases within the range of 1.75 to 1.25 s,the heave motion response of the structure decreases,whereas pitch,surge motion response,heave acceleration,and mooring force increase.The amplitudes of various motions and mooring forces of the structure decrease with de-creasing wave height.The hydrodynamic responses under irregular and regular waves follow similar patterns,but the responses and mooring forces induced by irregular waves are more significant.The structure should be designed based on the actual wave height.In addition,the same frequency resonance phenomenon is avoided because the movement period of each degree of freedom is close to the wave period.
基金partially funded by the National Natural Science Foundation of China(Grant No.52171329)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2024B1515020107)+1 种基金the Young Elite Scientist Sponsorship Program by CAST(Grant No.2022QNRC001)Characteristic Innovation Project of Universities in Guangdong Province(Grant No.2023KTSCX005).
文摘A multi-resolution smoothed particle hydrodynamics and peridynamics(SPH-PD)coupling model is proposed in this study for simulating the fracture characteristics of ice plates exposed to underwater blast loads.The SPH model employs a volume adaptive scheme(VAS)and a multi-resolution particle technique to accurately simulate explosive charge detonation and shock wave propagation.This approach addresses numerical challenges from charge expansion and significant size disparity between the charge and the fluid particles.The model captures the full underwater explosion process,covering both the shock wave phase and the bubble expansion stage,by applying appropriate equations of state for each respective phase.To analyze ice plate damage and crack propagation influenced by temperature changes,an ordinary state-based PD(OSB-PD)formulation with coupled mechanical and thermodynamic models is used.Numerical results show that the proposed coupling method demonstrates good agreement with reference solutions and experimental data.
文摘The growing utilization of the ocean as a renewable energy source drives the need for reliable maritime infrastructure.One major challenge for these structures is withstanding impulsive loads from extreme ocean waves,which requires materials with high strength and deformation resistance to maintain structural integrity.Metal Matrix Composite(MMC)is a promising material,yet studies on its behavior under impulsive loading remain limited.This study investigates the ultimate capacity of MMC sandwich structures using the Finite Element Method(FEM)through simulations with an Underwater Shock Loading Simulator(USLS).Validation against the results of He et al.confirms the accuracy of the simulation method.Results indicate that increasing flyer velocity from 135 to 195 m/s raises the maximum displacement from 5.83 mm to 10.7 mm.Increasing face sheet thickness from 0.4 to 1.8 mm reduces deformation from 4.95 to 3.09 mm,while increasing core thickness from 14 to 20 mm decreases deflection from 5.42 to 3.68 mm.Furthermore,the thickness ratio analysis indicates that the 1:10 configuration produces the smallest deformation(4.13 mm)and is more efficient because it provides higher stiffness with lower mass.These findings demonstrate that optimizing core and face sheet thickness significantly enhances structural resistance to deformation.The study concludes that a balanced thickness configuration is key to improving the structural performance of MMC sandwiches,supporting the design of stronger and more sustainable materials for maritime structures in extreme environments.
文摘This paper introduces a thermodynamically grounded framework that replaces conventional energy-centric building simulation with a heat-based reconstruction method,enabling the use of standard-year weather data without bespoke weather files.High-accuracy predictive models are developed to estimate seasonal heating and cooling loads and to derive convective heat transfer coefficients for transitional seasons.Models are calibrated against extended AMeDAS records for Kurume,Fukuoka Prefecture,demonstrating improved capture of local climatic variability compared with standard practice.Methodologically,the study establishes time-series regression relationships linking outdoor air temperature,incident solar radiation,and wind speed to instantaneous thermal demand and surface convective rates.These empirical relations feed a reconstruction algorithm that adjusts simulation outputs to standardized climatic conditions by rescaling heat flows and convective parameters rather than altering meteorological inputs.Results indicate that reframing simulation inputs in terms of heat enhances reliability and transferability of performance predictions and reduces uncertainty associated with variable weather.The paper examines essential assumptions affecting applicability,including the assumed linearity of convective correlations,representativeness of the reference building envelope,and the use of virtual walls for parameter identification.It further proposes a novel procedure to compute a physical adjustment coefficient for the convective heat transfer coefficient,addressing a parameter gap in macro-scale models while acknowledging challenges for conventional comparative validation.The authors recommend future work on automated calibration routines and on extending the method to tropical and arid climates to broaden applicability and support foundational reform of building energy simulation.
基金supported by the National Natural Science Foundation of China(Grant Nos.12102015 and 12472003)the General Program of Science and Technology Development Project of the Beijing Municipal Education Commission(Grant No.KM202110005030)the Key Research Project of Zhejiang Market Supervision Administration(Grant No.ZD2024013).
文摘The dynamics of beams subjected to moving loads are of practical importance since the responses caused by these loads can be greater than those under equivalent static loads in some cases.In this work,a novel inertial nonlinear energy sink(NES)is applied for the first time to achieve vibration suppression in beams under moving loads.Based on the Timoshenko beam theory,the nonlinear motion equations of a beam with an inertial NES are derived using the energy method and Lagrange equations.The Newmark-βmethod combined with the Heaviside step function is adopted to calculate the responses of the beam under moving loads of constant amplitude and harmonic excitation.The accuracy of the modelling derivation and solution methodology are validated through comparisons with results from other studies.The results demonstrate that the velocity and excitation frequency of the moving load significantly affect the response of the beam as well as the performance of the inertial NES.To enhance its effectiveness under various moving load conditions,parametric optimization is numerically performed.The optimized inertial NES can achieve good performance by efficiently reducing the maximum deflection of the beam.The findings of this study contribute to advancing the understanding and application of NESs in mitigating structural vibrations caused by moving loads.
