Load frequency control(LFC)is a critical function to balance the power consumption and generation.Thegrid frequency is a crucial indicator for maintaining balance.However,the widely used information and communication ...Load frequency control(LFC)is a critical function to balance the power consumption and generation.Thegrid frequency is a crucial indicator for maintaining balance.However,the widely used information and communication infrastructure for LFC increases the risk of being attacked by malicious actors.The dynamic load altering attack(DLAA)is a typical attack that can destabilize the power system,causing the grid frequency to deviate fromits nominal value.Therefore,in this paper,we mathematically analyze the impact of DLAA on the stability of the grid frequency and propose the network parameter regulation(NPR)to mitigate the impact.To begin with,the dynamic LFC model is constructed by highlighting the importance of the network parameter.Then,we model the DLAA and analyze its impact on LFC using the theory of second-order dynamic systems.Finally,we model the NPR and prove its effect in mitigating the DLAA.Besides,we construct a least-effort NPR considering its infrastructure cost and aim to reduce the operation cost.Finally,we carry out extensive simulations to demonstrate the impact of the DLAA and evaluate the mitigation performance of NPR.The proposed cost-benefit NPR approach can not only mitigate the impact of DLAA with 100%and also save 41.18$/MWh in terms of the operation cost.展开更多
Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early os...Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early osteoarthritis(OA),particularly among exercise enthusiasts,remains controversial.Here,we established in vitro and in vivo models of prolonged moderate mechanical loading(7.5%strain,1 Hz)and analyzed human cartilage from weight-bearing and non-weight-bearing regions using RNA sequencing.Prolonged exposure(≥12 h)significantly increased chondrocyte apoptosis(2.3-fold),reduced expression of the chondrogenic transcription factor SOX9 and the matrix markers COL2A1,and elevated nerve growth factor(NGF)expression(1.8-fold),accompanied by enrichment of neural sensitization and inflammatory pathways.Immunofluorescence staining revealed NGF accumulation in mechanically stressed cartilage.Unlike high-intensity stress,which led to immediate apoptosis,moderate loading induced a delayed pro-apoptotic response after 12 h.These findings indicate that prolonged moderate mechanical loading may promote chondrocyte apoptosis through an NGFmediated inflammatory microenvironment and provide mechanistic evidence suggesting that patients with early OA may benefit from limiting high-impact or prolonged moderate-intensity exercise sessions to prevent cartilage damage and guide rehabilitation.展开更多
This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and...This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and the stress and aerodynamic load measurement points are reasonably arranged accordingly.The actual measurement is carried out in combination with the operating conditions of the existing lines.The stress variations and spectral characteristics of the train under different speed levels(80,160,180,200 km/h),tunnel entry and exit,and scraper action conditions were compared and analyzed.The stress amplification factors under tunnel intersection and scraper action were obtained,providing boundary conditions for the design of wipers for highspeed s.The research results show that the maximum stress of the wiper structure obtained through simulation calculation is concentrated at the connection of the wiper arm.Structural stress increases with the rise of speed grade.The stress increases by 1.11 times when the tunnel meets.When the scraper operates,the stress on the scraper arm increases by 4.1–7.6 times.Due to the broadband excitation effect of the aerodynamic load,the spectral energy of the structure is relatively high at the natural frequency,which excites the natural mode of the wiper.展开更多
Conventionally,foundations have been classified as shallow or deep in routine civil engineering practice.However,due to recent developments,two other approaches,semi-deep and ground modification foundations,are now av...Conventionally,foundations have been classified as shallow or deep in routine civil engineering practice.However,due to recent developments,two other approaches,semi-deep and ground modification foundations,are now available,complicating foundation categorization.Accordingly,a new concept for foundation categorization is introduced in this paper based on insights into the theory of structure analysis.Based on the form aspect,foundation systems can be categorized as one-dimensional(linear),two-dimensional(planar),and threedimensional(volumetric).Based on the load transfer aspect,foundations can also be categorized as vector-acting(piles),section or surface-acting(rafts and shells),and block-acting(piled rafts).As a step toward implementing this new categorization scheme,a database of 22 cases has been compiled,symbolizing novel introduced foundation systems.This compilation involves structures such as offshore jackets,high-rise buildings,towers and storages,and diverse geomaterials.Among them,a few have been selected for detailed evaluation,emphasizing influential factors in foundation selection,comprising superstructure,subsoil condition,foundation system,circumferential conditions,and supplementary considerations,that is,constructional and sustainability-based issues.Lessons learned from experience and these knowledge-based cases have described for foundation selection and implementation.Geotechnical and practical aspects with critical components have been realized as major performance assessment and comparison factors.Foundation systems have been compared and ranked using the improved analytic hierarchy process approach.Finally,four categories of buildings,from low-rise to towers and four prevailing levels of soil strength,from soft to very hard,have been considered to propose a perspective for building substructure implementation,adapted via relevant cases.Overall,the introduced categorization is recognized as an efficient algorithm for the experimentation of appropriate foundations for specific structures and subsoil conditions.展开更多
The variation laws of runoff and sediment load under different climate,vegetation,and human activity scenarios are significantly different.Exploring the impacts of climate change and human activities on runoff and sed...The variation laws of runoff and sediment load under different climate,vegetation,and human activity scenarios are significantly different.Exploring the impacts of climate change and human activities on runoff and sediment load dynamics can provide a profound understanding of the mechanism of runoff and sediment load variability in basins,which is crucial for the sustainable development of regional ecosystems.This study investigates the Tao River Basin(TRB)on the Tibetan Plateau,as well as the Zuli River Basin(ZRB)and Jing River Basin(JRB)on the Loess Plateau,to differentiate the impacts of climate change and human activities on runoff and sediment load dynamics.The runoff and sediment load of the three watersheds have shown a decreasing trend over the past 40 years,and combined with the DMC(Dual mass curve)method,it was found that the slope of the runoff sediment gradually tends to flatten out.After the time period was divided,the CA(Cumulative anomaly)method was used for verification,which revealed good correspondence between the two before 2000 and then gradual deviations.The power function best represents the relationship between runoff and sediment load.During the initial period,climate had a significant impact on runoff variation in the TRB and JRB,with contribution rates of-54.93%and-63.02%,respectively.In the later period,human activities became the dominant influence,contributing more than-60%of the runoff variation.In the ZRB,human activities consistently dominated runoff variation,with contribution rates of-72.72%and-55.66%during both periods.In the early stages of research,the impact of climate change on sediment load was more severe in the TRB and JRB,and human activities played a significant role in the later stages.However,in the ZRB,human activities have always been the main contributor.Based on the actual local situation,runoff and sediment load in the TRB are influenced primarily by engineering measures,and vegetation and check dams exert greater impacts on the ZRB and JRB.This study explores the attribution of water and sediment load changes in different ecological geographic regions from a comparative perspective,providing a valuable theoretical basis and reference for understanding global runoff and sediment transport changes in similar areas.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
Recent advancements in genome sequencing have enabled the estimation of genetic load through deleterious mutation profiling.However,Chinese populations remain underexplored in this context.We analyze whole-exome seque...Recent advancements in genome sequencing have enabled the estimation of genetic load through deleterious mutation profiling.However,Chinese populations remain underexplored in this context.We analyze whole-exome sequencing data from 5002 individuals,encompassing major Han subgroups―North Han(NHan),South Han(S-Han),and Guangxi Han(G-Han)―as well as 13 ethnic minorities.Notably,G-Han exhibits significant genetic affinity with the Zhuang population.Systematic curation of 2110 ClinVar pathogenic or likely pathogenic variants reveals 93.4%are ultra-rare.Exceptions include GJB2 rs72474224-A(hearing loss),which shows higher frequencies in Zhuang and G-Han,and β-thalassemia-associated HBB variants(rs33986703-A and rs33950507-T),which are elevated in G-Han compared to other Han subgroups.Among 96 autosomal dominant mutation carriers,LDLR variants are predominant(~25%),with comparable frequencies across Han subgroups.Adaptive signatures highlight gene-environment interactions:MTHFR rs1801133-A(UV adaptation)declines southward,while ALDH2 rs671-A(alcohol metabolism)displays the opposite trend.ABCC11 rs17822931-A,associated with cold adaptation,is particularly low frequency in G-Han.Gene-based rare-variant collapsing analyses identify an elevated risk of retinitis pigmentosa in S-Han(PRPF4,TUB).Our findings demonstrate that genetic load in Chinese populations is influenced by demographic history,population structure,and regional adaptation,emphasizing the importance of population-specific frameworks in precision medicine.展开更多
This study investigates the performance of high-strength cable bolts under impact loading conditions representative of rock bursts in underground environments.Although widely used,the dynamic behaviour of these cable ...This study investigates the performance of high-strength cable bolts under impact loading conditions representative of rock bursts in underground environments.Although widely used,the dynamic behaviour of these cable bolts has received limited experimental attention,and their effectiveness in seismically active zones remains a subject of ongoing debate.To address this gap,a reverse pull-out test machine integrated with a drop hammer rig was employed.Tests were conducted on 70-t SUMO bulbed and non-bulbed cable bolts with encapsulation lengths of 300 and 450 mm,subjected to an impact energy of 14.52 k J.Results indicate that non-bulbed cables,despite showing lower initial peak loads(average 218 vs.328 k N for bulbed cables at 300 mm encapsulation),demonstrated superior energy absorption(average 11.26 vs.8.75 k J)and displacement capacity(average 48.40 vs.36.25 mm).Increasing the encapsulation length for bulbed cables led to a reduction in initial peak load but improved displacement and energy absorption.The dominant failure mechanism was debonding at the cable-grout interface,characterised by frictional sliding and cable rotation.These findings provide new insights into the energy dissipation mechanisms of cables and support the development of more resilient ground support systems for dynamically active conditions.展开更多
Large-scale geological energy storage plays a crucial role in balancing the intermittency of renewable energy.As an energy storage medium,soaked sandstone has a wide range of applications in geological energy storage....Large-scale geological energy storage plays a crucial role in balancing the intermittency of renewable energy.As an energy storage medium,soaked sandstone has a wide range of applications in geological energy storage.Understanding the damage characteristics in soaked sandstones is essential for ensuring the stability and longevity of these energy storage systems.This study involved multi-stage cyclic loading tests conducted on soaked sandstone to explore the damage evolution throughout the loading process.The findingsreveal several important insights:(1)The plastic hysteresis loops observed during multi-stage cyclic loading evolved from dense to sparse.An increase in stress level led to greater damage in the rock,as evidenced by an increase in accumulated peak/plastic strains.(2)Energy density and stress level are related by quadratic polynomial relationships.The elastic and dissipated energy densities are related by a linear law.The average energy storage coefficientdecreased by up to 24.1%with increasing stress amplitude,reflectingchanges in energy dynamics within the samples.(3)AE counts,amplitude,and frequency provided critical insights into rock damage and fracture patterns.The greater the loading rate and stress amplitude,the lower the proportion of high-amplitude,high-peak frequency,and shear-type fractures.Increasing stress amplitude caused a maximum 16.63%reduction in the AE bvalue,indicating shifts in fracture behavior under varying stress conditions.(4)The increase in loading rate and stress amplitude promotes the transformation of micropores and mesopores to macropores/microcracks.(5)Damage variables,definedin terms of cumulative dissipation energy,aligned closely with the fatigue damage model under multi-stage cyclic loading.Accelerated damage primarily occurred during the finalstages of fatigue loading,highlighting critical periods in the degradation of soaked sandstones.This study can offer guidance for designing operational parameters for energy storage geological bodies dominated by soaked sandstones.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
The multi-pass intermittent local loading process,which features a more flexible processing path,can further enhance the second material distribution during local loading,improve the formability of components,and redu...The multi-pass intermittent local loading process,which features a more flexible processing path,can further enhance the second material distribution during local loading,improve the formability of components,and reduce forming loads.However,the absence of compatible forming equipment makes it difficult to control the constraint in the unloaded zones during the forming process.This difficulty complicates coordination and control of deformation,particularly for asymmetric rib-web components.Additionally,the current implementation involves multi-fire heating,a long process flow,and high energy consumption,which limits the popularization and application of the local loading process.In this study,a new multi-pass local loading hydraulic forming apparatus that can quickly and reliably switch between heavy-load deformation and low-load constraint for different local loading sub-dies was developed.A 10-tonne laboratory prototype was developed,and the forming characteristics during the forming process as well as the response characteristics of the hydraulic system during the multi-pass intermittent local loading of rib-web component were investigated using numerical simulations and physical experiments.Results indicated that,compared to a whole loading process with the same initial geometry of billet,the total forming load(i.e.,the sum of loaded and restrained loads)is reduced by more than 40%with the local loading process,and by nearly 50%with multi-pass local loading.The multi-pass local loading process allows for more effective control of material flow compared to single-pass local loading,leading to improved cavity filling and reduced flow line disturbance.For a large-scale,complex titanium alloy bulkhead,the cavity filling problem was addressed by optimizing the multi-pass local loading path with an unequal thickness billet.The dynamic performance of the multi-pass local loading hydraulic system was found to be robust,with stable pressure transitions during motion and load switching for the sub-die(s).The dynamic characteristic of the hydraulic cylinder when switching from non-moving/unloaded state to a moving/loading state are consistent whether a load is present or not.However,the dynamic characteristics differ when switching from a moving/loading state to non-moving/unloaded state,showing opposite behavior.The developed hydraulic drive mechanism provides a way for implementation of multi-pass local loading without auxiliary operation and extra heating.The results of the study provide a foundation for the industrial production of large-scale,complex components with reduced force requirement and low-energy consumption.展开更多
With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at ...With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at different temperatures in combination with real-time acoustic emission(AE)monitoring.The results show that the cumulative AE count increases stepwise with increasing cyclic stress.The peak frequency is concentrated primarily in the medium-frequency range,exhibiting a band distribution across low-,medium-,and high-frequency ranges.As the temperature increases,the proportion of low-frequency signals decreases from 14.32%to 5.76%,whereas the proportion of medium-frequency signals increases from 85.48%to 94.1%.The proportion of high-frequency signals remains relatively constant between 0.1%and 0.2%.The amplitude-count relationship of the AE signals demonstrates a strong negative power-law correlation.Furthermore,with increasing temperature,the negative power-law exponent of the amplitude gradually decreases,with the b value decreasing from 1.096 to 0.837 and the a value decreasing from 7.4871 to 6.6982.Under all four temperature conditions,the dominant failure mode in rock salt is tensile cracking.However,as the temperature increases,the proportion of tensile cracks decreases from 88.59%to 75.12%,whereas the proportion of shear cracks at 80℃is nearly double that at 20℃.This finding indicates that as the temperature increases,the ductility of the material increases,and the crack propagation mode shifts from tensile to shear.This research provides valuable insights for the design and stability assessment of salt cavern reservoirs for deep underground energy storage systems.展开更多
This study examined non-uniform loading in goaf cantilever rock masses via testing,modeling,and mechanical analysis to solve instantaneous fracture and section buckling from mining abutment pressure.The study investig...This study examined non-uniform loading in goaf cantilever rock masses via testing,modeling,and mechanical analysis to solve instantaneous fracture and section buckling from mining abutment pressure.The study investigates the non-uniform load gradient effect on fracture characteristics,including load characteristics,fracture location,fracture distribution,and section roughness.A digital model for fracture interface buckling analysis was developed,elucidating the influence of non-uniform load gradients on Fracture Interface Curvature(FIC),Buckling Rate of Change(BRC),and Buckling Domain Field(BDF).The findings reveal that nonlinear tensile stress concentration and abrupt tensile-compressive-shear strain mutations under non-uniform loading are fundamental mechanisms driving fracture path buckling in cantilever rock mass structures.The buckling process of rock mass under non-uniform load can be divided into two stages:low load gradient and high gradient load.In the stage of low gradient load,the buckling behavior is mainly reflected in the compression-shear fracture of the edge.In the stage of high gradient load,a buckling band along the loading direction is gradually formed in the rock mass.These buckling principles establish a theoretical basis for accurately characterizing bearing fractures,fracture interface instability,and vibration sources within overlying cantilever rock masses in goaf.展开更多
Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigate...Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigates the effects of sheath(duct)implementation and confinement assumptions through nonlinear finite element analysis.Four modeling cases were defined,consisting of an explicit sheath without tendon-concrete confinement(S)and three no-sheath variants with different confinement levels(X,N,A).One-way beams and two-way panels were analyzed,and panel blast responses were validated against experimental results.In both beams and panels,average initial stress levels were similar across models,through local stress concentrations appeared when the sheath was modeled.Under blast loading,these local effects became critical,and the sheath-implemented model reproduced experimental behavior most accurately,whereas non-implemented models deviated.Reduced blast intensity diminished the differences among models,thereby reaffirming that sheath-induced localization and damage propagation are critical factors.These findings highlight the importance of explicit sheath implementation for realistic numerical assessment of unbonded PT structures under extreme loads.展开更多
Air conditioning is a major energy-consuming component in buildings,and accurate air conditioning load forecasting is of great significance for maximizing energy utilization efficiency.However,the deep learning models...Air conditioning is a major energy-consuming component in buildings,and accurate air conditioning load forecasting is of great significance for maximizing energy utilization efficiency.However,the deep learning models currently used in the field of air conditioning load forecasting often suffer from issues such as distribution bias in load data and insufficient expression ability of nonlinear features in the model,which affect the accuracy of load forecasting.To address this,this paper proposes a novel load forecasting model.Firstly,the model employs the Dish-TS(DS)module to standardize the input window data through self-learning standardized parameters,thereby addressing the spatial intra-bias problem existing between data.Secondly,DS-Kansformer introduces Kolmogorov-Arnold Networks(KANs)to enhance the expression ability of nonlinear features.Finally,the output window is denormalized through the self-learning parameter of the DS module to restore the original distribution of the predicted data.In this paper,experiments were carried out based on the air-conditioning load dataset collected from a multi-functional comprehensive building,and the experimental results show that after adding the DS module,the Mean Absolute Error(MAE),Root Mean Square Error(RMSE),and R-squared(R^(2))of the model are 20.46%,34.44%,and 92.61%,respectively;after introducing KAN,the MAE,RMSE,and R^(2) are 22.81%,35.72%,and 92.05%,respectively;the model also exhibits high prediction accuracy after integrating the two modules(with RMSE,MAE,and R^(2) being 19.75%,34.05%,and 92.78%,respectively),outperforming common time series prediction models,confirming the reliability and efficiency of the model,which can provide reliable support for intelligent energy management in buildings.展开更多
This paper investigates the detection and mitigation of coordinated cyberattacks on Load Frequency Control(LFC)systems integrated with Battery Energy Storage Systems(BESS).As renewable energy sources gain greater pene...This paper investigates the detection and mitigation of coordinated cyberattacks on Load Frequency Control(LFC)systems integrated with Battery Energy Storage Systems(BESS).As renewable energy sources gain greater penetration,power grids are becoming increasingly vulnerable to cyber threats,potentially leading to frequency instability and widespread disruptions.We model two significant attack vectors:load-altering attacks(LAAs)and false data injection attacks(FDIAs)that corrupt frequency measurements.These are analyzed for their impact on grid frequency stability in both linear and nonlinear LFC models,incorporating generation rate constraints and nonlinear loads.A coordinated attack strategy is presented,combining LAAs and FDIAs to achieve stealthiness by concealing frequency deviations from system operators,thereby maximizing disruption while evading traditional detection.To counteract these threats,we propose an Unknown Input Observer(UIO)-based detection framework for linear and nonlinear LFCs.The UIO is designed using linear matrix inequalities(LMIs)to estimate system states while isolating unknown attack inputs,enabling attack detection through monitoring measurement residuals against a predefined threshold.For mitigation,we leverage BESS capabilities with two adaptive strategies:dynamic mitigation for dynamic LAAs,which tunes BESS parameters to enhance the system’s stability margin and accelerate convergence to equilibrium;and staticmitigation for static LAAs and FDIAs.Simulations show that the UIO achieves high detection accuracy,with residuals exceeding thresholds promptly under coordinated attacks,even in nonlinear models.Mitigation strategies reduce frequency deviations by up to 80%compared to unmitigated cases,restoring stability within seconds.展开更多
The growing demands on global infrastructure highlight the critical need for durable and efficient pavement systems,particularly under the stress of repetitive heavy traffic loads.The use of geosynthetics within the p...The growing demands on global infrastructure highlight the critical need for durable and efficient pavement systems,particularly under the stress of repetitive heavy traffic loads.The use of geosynthetics within the pavement structure increases the load-carrying capacity of unbound pavement layers by providing lateral restraint,improving vertical stress distribution,and enhancing bearing capacity.Such reinforcement typically aims to either improve the service life of pavements or achieve equivalent performance with a reduced granular cover.Previous and ongoing research quantifies geosynthetic performance in pavement reinforcement using various testing methods.Among these,laboratory model box tests subjected to cyclic loading are pivotal,as they closely replicate real-world traffic conditions.Hence,these studies are essential for understanding how geosynthetics distribute loads and enhance pavement durability.This facilitates the development of optimized geosynthetic design and installation practices,accelerating the loading process to simulate years of traffic wear in a shorter period.This review discusses the improved rutting resistance of unbound pavements reinforced with geosynthetic materials,specifically drawing on data from cyclic plate load tests conducted on laboratory model boxes,as highlighted in the literature.Key variables such as optimum geosynthetic placement,geosynthetic material properties,performance of different geosynthetic materials and the effects of aperture shape and size on rutting resistance are discussed.Furthermore,the review assesses various predictive rutting models,analysing their applicability and accuracy in forecasting the rutting performance of geosynthetic-reinforced unbound pavements.This comprehensive literature review aids pavement engineers and researchers,in guiding the selection and design of geosynthetics to optimize pavement durability and functionality under repetitive traffic loads.展开更多
Railway noise barriers are an essential piece of infrastructure for reducing noise propagation.However,these barriers experience aerodynamic loads generated by high-speed trains,leading to dynamic effects that may com...Railway noise barriers are an essential piece of infrastructure for reducing noise propagation.However,these barriers experience aerodynamic loads generated by high-speed trains,leading to dynamic effects that may compromise their fatigue capacity.The most common structural design for railway noise barriers consists of vertical configurations of posts and panels.However,there have been few dynamic analyses of steel post/wood panel noise barriers under train-induced aerodynamic loads.This study used dynamic finite element analysis to assess the dynamic behavior of such noise barriers.Analysis of a 40-m-long noise barrier model and a triangular simplified load model,the latter of which effectively represented the detailed aerodynamic load,were first used to establish the model and input of the moving load during dynamic simulation.Then,the effects of different parameters on the dynamic response of the noise barrier were evaluated,including the damping ratio,the profile of the steel post,the span length of the panel,the barrier height,and the train speed.Gray relational analysis indicated that barrier height exhibited the highest correlations with the dynamic responses,followed by train speed,post profile,span length,and damping ratio.A reduction in the natural frequency and an increase in the train speed result in a higher peak response and more pronounced fluctuations between the nose and tail waves.The dynamic amplification factor(DAF)was found to be related to both the natural frequency and train speed.A model was proposed showing that the DAF significantly increases as the square of the natural frequency decreases and the cube of the train speed rises.展开更多
Frozen moraine soils are widely distributed across the Tianshan Mountains,the Qinghai-Tibetan Plateau,and other high-altitude regions.Engineering activities,particularly blasting,often induce degradation of the soil m...Frozen moraine soils are widely distributed across the Tianshan Mountains,the Qinghai-Tibetan Plateau,and other high-altitude regions.Engineering activities,particularly blasting,often induce degradation of the soil microstructure,compromising its mechanical integrity and increasing the risk of slope instability and rainfall-triggered debris flows-posing serious threats to infrastructure in cold regions.Previous studies have largely treated frozen soils as homogeneous continua,thereby overlooking key micro-scale processes such as ice-soil interaction,microcrack propagation,and particle breakage.In this study,the dynamic mechanical behavior and microstructural damage mechanisms of frozen moraine soil were systematically investigated under varying temperatures(−5℃,−15℃,and−25℃)and strain rates(50 s^(-1),70 s^(-1),and 90 s^(-1)).Results reveal that both temperature and strain rate significantly influence the dynamic stress-strain response.Energy absorption exhibits a three-stage pattern of increase,stabilization,and decline.At−25℃,increased ice brittleness reduces the peak energy absorption efficiency under impact.To capture the observed nonlinear behavior,a damage-based constitutive model was developed,incorporating coupled effects of impact-induced microcracking,ice-soil interfacial debonding,and particle fracture.The stochastic evolution of interfacial debonding and grain breakage was described using a Weibull statistical framework,linking microstructural deterioration to macroscopic response.The model shows strong agreement with experimental data and accurately simulates key parameters such as peak stress and energy absorption.These findings enhance the understanding of dynamic damage mechanisms in frozen soils and offer a computational tool for the safety assessment and hazard mitigation of engineering structures in cold,high-altitude environments.展开更多
Nanotechnology has provided thousands of novel nano-antimicrobials possessing features uncommon in clinically available antimicrobials.Here,nanocarriers loaded with conventional antimicrobials and responding to enviro...Nanotechnology has provided thousands of novel nano-antimicrobials possessing features uncommon in clinically available antimicrobials.Here,nanocarriers loaded with conventional antimicrobials and responding to environmental changes upon entry into oral biofilms are reviewed.Supra-gingival biofilms are characterized by acidic pH,the presence of bacterial enzymes,and the development of hypoxia in deeper layers.Sub-gingival biofilms are slightly alkaline,with hypoxia occurring over their entire depth.Upon entering biofilms,negatively charged,pH-and/or hypoxia-responsive nanocarriers become positively charged.This charge reversal leads to electrostatic double-layer attraction between positively charged nanocarriers towards negatively charged,waterfilled channel walls in biofilms,enhancing their accumulation in a biofilm.Degradation of bacterial enzyme-responsive nanocarriers causes in-biofilm release of antimicrobial cargo,yielding higher local antimicrobial concentrations than can be achieved through their direct,oral administration without harming soft tissues.Enhanced antibiofilm activity after in-biofilm antimicrobial release from biofilm-responsive micelles and liposomes has been demonstrated in vitro towards single-species Streptococcus mutans and Staphylococcus aureus biofilms or in vivo using specific-pathogen-free rodents inoculated with selected pathogens.This preferential antibacterial activity regulated the microbial composition of ex vivo human oral biofilm towards a more healthy microbiome composition.Although clinical confirmation is limited,the potential benefits of stimuli-responsive,antimicrobial-loaded nanocarriers for oral biofilm control and microbiome restoration are worth further investigation towards clinical translation.展开更多
基金supported by the project Major Scientific and Technological Special Project of Guizhou Province([2024]014).
文摘Load frequency control(LFC)is a critical function to balance the power consumption and generation.Thegrid frequency is a crucial indicator for maintaining balance.However,the widely used information and communication infrastructure for LFC increases the risk of being attacked by malicious actors.The dynamic load altering attack(DLAA)is a typical attack that can destabilize the power system,causing the grid frequency to deviate fromits nominal value.Therefore,in this paper,we mathematically analyze the impact of DLAA on the stability of the grid frequency and propose the network parameter regulation(NPR)to mitigate the impact.To begin with,the dynamic LFC model is constructed by highlighting the importance of the network parameter.Then,we model the DLAA and analyze its impact on LFC using the theory of second-order dynamic systems.Finally,we model the NPR and prove its effect in mitigating the DLAA.Besides,we construct a least-effort NPR considering its infrastructure cost and aim to reduce the operation cost.Finally,we carry out extensive simulations to demonstrate the impact of the DLAA and evaluate the mitigation performance of NPR.The proposed cost-benefit NPR approach can not only mitigate the impact of DLAA with 100%and also save 41.18$/MWh in terms of the operation cost.
基金supported by the Zhejiang Medical and Health Innovation Talent Support Project(Grant No.2021RC128 to S.S.)Zhejiang Medicine and Health Science and Technology Project(2025KY1540 to J.J.L.)+3 种基金Zhejiang Province Health Science and Technology Project(2024KY409 and 2021KY1086 to J.Y.L.)Huzhou Science and Technology Planning Project(2020GY10 to W.L.,2022GZ65 to J.Y.L.)Huzhou Basic and Clinical Translation of Orthopedics Key Laboratory(Grant No.HZGKSYS01Y to S.S.)South Taihu Lake Outstanding Young Health Talents Cultivation Program(Grant No.rsk2023001 to S.S.).
文摘Articular cartilage maintains joint homeostasis by adapting to mechanical loading,but both insufficient and excessive loading can impair cartilage integrity.Whether mechanical activity should be restricted in early osteoarthritis(OA),particularly among exercise enthusiasts,remains controversial.Here,we established in vitro and in vivo models of prolonged moderate mechanical loading(7.5%strain,1 Hz)and analyzed human cartilage from weight-bearing and non-weight-bearing regions using RNA sequencing.Prolonged exposure(≥12 h)significantly increased chondrocyte apoptosis(2.3-fold),reduced expression of the chondrogenic transcription factor SOX9 and the matrix markers COL2A1,and elevated nerve growth factor(NGF)expression(1.8-fold),accompanied by enrichment of neural sensitization and inflammatory pathways.Immunofluorescence staining revealed NGF accumulation in mechanically stressed cartilage.Unlike high-intensity stress,which led to immediate apoptosis,moderate loading induced a delayed pro-apoptotic response after 12 h.These findings indicate that prolonged moderate mechanical loading may promote chondrocyte apoptosis through an NGFmediated inflammatory microenvironment and provide mechanistic evidence suggesting that patients with early OA may benefit from limiting high-impact or prolonged moderate-intensity exercise sessions to prevent cartilage damage and guide rehabilitation.
文摘This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and the stress and aerodynamic load measurement points are reasonably arranged accordingly.The actual measurement is carried out in combination with the operating conditions of the existing lines.The stress variations and spectral characteristics of the train under different speed levels(80,160,180,200 km/h),tunnel entry and exit,and scraper action conditions were compared and analyzed.The stress amplification factors under tunnel intersection and scraper action were obtained,providing boundary conditions for the design of wipers for highspeed s.The research results show that the maximum stress of the wiper structure obtained through simulation calculation is concentrated at the connection of the wiper arm.Structural stress increases with the rise of speed grade.The stress increases by 1.11 times when the tunnel meets.When the scraper operates,the stress on the scraper arm increases by 4.1–7.6 times.Due to the broadband excitation effect of the aerodynamic load,the spectral energy of the structure is relatively high at the natural frequency,which excites the natural mode of the wiper.
文摘Conventionally,foundations have been classified as shallow or deep in routine civil engineering practice.However,due to recent developments,two other approaches,semi-deep and ground modification foundations,are now available,complicating foundation categorization.Accordingly,a new concept for foundation categorization is introduced in this paper based on insights into the theory of structure analysis.Based on the form aspect,foundation systems can be categorized as one-dimensional(linear),two-dimensional(planar),and threedimensional(volumetric).Based on the load transfer aspect,foundations can also be categorized as vector-acting(piles),section or surface-acting(rafts and shells),and block-acting(piled rafts).As a step toward implementing this new categorization scheme,a database of 22 cases has been compiled,symbolizing novel introduced foundation systems.This compilation involves structures such as offshore jackets,high-rise buildings,towers and storages,and diverse geomaterials.Among them,a few have been selected for detailed evaluation,emphasizing influential factors in foundation selection,comprising superstructure,subsoil condition,foundation system,circumferential conditions,and supplementary considerations,that is,constructional and sustainability-based issues.Lessons learned from experience and these knowledge-based cases have described for foundation selection and implementation.Geotechnical and practical aspects with critical components have been realized as major performance assessment and comparison factors.Foundation systems have been compared and ranked using the improved analytic hierarchy process approach.Finally,four categories of buildings,from low-rise to towers and four prevailing levels of soil strength,from soft to very hard,have been considered to propose a perspective for building substructure implementation,adapted via relevant cases.Overall,the introduced categorization is recognized as an efficient algorithm for the experimentation of appropriate foundations for specific structures and subsoil conditions.
基金funding from the Natural Science Foundation of Shanxi Province(202403021222245,20240302121217)。
文摘The variation laws of runoff and sediment load under different climate,vegetation,and human activity scenarios are significantly different.Exploring the impacts of climate change and human activities on runoff and sediment load dynamics can provide a profound understanding of the mechanism of runoff and sediment load variability in basins,which is crucial for the sustainable development of regional ecosystems.This study investigates the Tao River Basin(TRB)on the Tibetan Plateau,as well as the Zuli River Basin(ZRB)and Jing River Basin(JRB)on the Loess Plateau,to differentiate the impacts of climate change and human activities on runoff and sediment load dynamics.The runoff and sediment load of the three watersheds have shown a decreasing trend over the past 40 years,and combined with the DMC(Dual mass curve)method,it was found that the slope of the runoff sediment gradually tends to flatten out.After the time period was divided,the CA(Cumulative anomaly)method was used for verification,which revealed good correspondence between the two before 2000 and then gradual deviations.The power function best represents the relationship between runoff and sediment load.During the initial period,climate had a significant impact on runoff variation in the TRB and JRB,with contribution rates of-54.93%and-63.02%,respectively.In the later period,human activities became the dominant influence,contributing more than-60%of the runoff variation.In the ZRB,human activities consistently dominated runoff variation,with contribution rates of-72.72%and-55.66%during both periods.In the early stages of research,the impact of climate change on sediment load was more severe in the TRB and JRB,and human activities played a significant role in the later stages.However,in the ZRB,human activities have always been the main contributor.Based on the actual local situation,runoff and sediment load in the TRB are influenced primarily by engineering measures,and vegetation and check dams exert greater impacts on the ZRB and JRB.This study explores the attribution of water and sediment load changes in different ecological geographic regions from a comparative perspective,providing a valuable theoretical basis and reference for understanding global runoff and sediment transport changes in similar areas.
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(NSFC)grants(32030020,32288101,32470649,323B2013,32300499,32270665)the National Key Research and Development Program of China(2023YFC2605400)+1 种基金the Shanghai Science and Technology Commission Program(25JS2810100,23JS1410100,QNKJ2024023)the Office of Global Partnerships(Key Projects Development Fund).
文摘Recent advancements in genome sequencing have enabled the estimation of genetic load through deleterious mutation profiling.However,Chinese populations remain underexplored in this context.We analyze whole-exome sequencing data from 5002 individuals,encompassing major Han subgroups―North Han(NHan),South Han(S-Han),and Guangxi Han(G-Han)―as well as 13 ethnic minorities.Notably,G-Han exhibits significant genetic affinity with the Zhuang population.Systematic curation of 2110 ClinVar pathogenic or likely pathogenic variants reveals 93.4%are ultra-rare.Exceptions include GJB2 rs72474224-A(hearing loss),which shows higher frequencies in Zhuang and G-Han,and β-thalassemia-associated HBB variants(rs33986703-A and rs33950507-T),which are elevated in G-Han compared to other Han subgroups.Among 96 autosomal dominant mutation carriers,LDLR variants are predominant(~25%),with comparable frequencies across Han subgroups.Adaptive signatures highlight gene-environment interactions:MTHFR rs1801133-A(UV adaptation)declines southward,while ALDH2 rs671-A(alcohol metabolism)displays the opposite trend.ABCC11 rs17822931-A,associated with cold adaptation,is particularly low frequency in G-Han.Gene-based rare-variant collapsing analyses identify an elevated risk of retinitis pigmentosa in S-Han(PRPF4,TUB).Our findings demonstrate that genetic load in Chinese populations is influenced by demographic history,population structure,and regional adaptation,emphasizing the importance of population-specific frameworks in precision medicine.
文摘This study investigates the performance of high-strength cable bolts under impact loading conditions representative of rock bursts in underground environments.Although widely used,the dynamic behaviour of these cable bolts has received limited experimental attention,and their effectiveness in seismically active zones remains a subject of ongoing debate.To address this gap,a reverse pull-out test machine integrated with a drop hammer rig was employed.Tests were conducted on 70-t SUMO bulbed and non-bulbed cable bolts with encapsulation lengths of 300 and 450 mm,subjected to an impact energy of 14.52 k J.Results indicate that non-bulbed cables,despite showing lower initial peak loads(average 218 vs.328 k N for bulbed cables at 300 mm encapsulation),demonstrated superior energy absorption(average 11.26 vs.8.75 k J)and displacement capacity(average 48.40 vs.36.25 mm).Increasing the encapsulation length for bulbed cables led to a reduction in initial peak load but improved displacement and energy absorption.The dominant failure mechanism was debonding at the cable-grout interface,characterised by frictional sliding and cable rotation.These findings provide new insights into the energy dissipation mechanisms of cables and support the development of more resilient ground support systems for dynamically active conditions.
基金sponsored by National Natural Science Foundation of China(Grant Nos.U22B6003 and 52304070)Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Chinese Academy of Sciences(Grant No.SKLGME-JBGS2404).
文摘Large-scale geological energy storage plays a crucial role in balancing the intermittency of renewable energy.As an energy storage medium,soaked sandstone has a wide range of applications in geological energy storage.Understanding the damage characteristics in soaked sandstones is essential for ensuring the stability and longevity of these energy storage systems.This study involved multi-stage cyclic loading tests conducted on soaked sandstone to explore the damage evolution throughout the loading process.The findingsreveal several important insights:(1)The plastic hysteresis loops observed during multi-stage cyclic loading evolved from dense to sparse.An increase in stress level led to greater damage in the rock,as evidenced by an increase in accumulated peak/plastic strains.(2)Energy density and stress level are related by quadratic polynomial relationships.The elastic and dissipated energy densities are related by a linear law.The average energy storage coefficientdecreased by up to 24.1%with increasing stress amplitude,reflectingchanges in energy dynamics within the samples.(3)AE counts,amplitude,and frequency provided critical insights into rock damage and fracture patterns.The greater the loading rate and stress amplitude,the lower the proportion of high-amplitude,high-peak frequency,and shear-type fractures.Increasing stress amplitude caused a maximum 16.63%reduction in the AE bvalue,indicating shifts in fracture behavior under varying stress conditions.(4)The increase in loading rate and stress amplitude promotes the transformation of micropores and mesopores to macropores/microcracks.(5)Damage variables,definedin terms of cumulative dissipation energy,aligned closely with the fatigue damage model under multi-stage cyclic loading.Accelerated damage primarily occurred during the finalstages of fatigue loading,highlighting critical periods in the degradation of soaked sandstones.This study can offer guidance for designing operational parameters for energy storage geological bodies dominated by soaked sandstones.
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the supports of the National Natural Science Foundation of China(Grant No.52375378)。
文摘The multi-pass intermittent local loading process,which features a more flexible processing path,can further enhance the second material distribution during local loading,improve the formability of components,and reduce forming loads.However,the absence of compatible forming equipment makes it difficult to control the constraint in the unloaded zones during the forming process.This difficulty complicates coordination and control of deformation,particularly for asymmetric rib-web components.Additionally,the current implementation involves multi-fire heating,a long process flow,and high energy consumption,which limits the popularization and application of the local loading process.In this study,a new multi-pass local loading hydraulic forming apparatus that can quickly and reliably switch between heavy-load deformation and low-load constraint for different local loading sub-dies was developed.A 10-tonne laboratory prototype was developed,and the forming characteristics during the forming process as well as the response characteristics of the hydraulic system during the multi-pass intermittent local loading of rib-web component were investigated using numerical simulations and physical experiments.Results indicated that,compared to a whole loading process with the same initial geometry of billet,the total forming load(i.e.,the sum of loaded and restrained loads)is reduced by more than 40%with the local loading process,and by nearly 50%with multi-pass local loading.The multi-pass local loading process allows for more effective control of material flow compared to single-pass local loading,leading to improved cavity filling and reduced flow line disturbance.For a large-scale,complex titanium alloy bulkhead,the cavity filling problem was addressed by optimizing the multi-pass local loading path with an unequal thickness billet.The dynamic performance of the multi-pass local loading hydraulic system was found to be robust,with stable pressure transitions during motion and load switching for the sub-die(s).The dynamic characteristic of the hydraulic cylinder when switching from non-moving/unloaded state to a moving/loading state are consistent whether a load is present or not.However,the dynamic characteristics differ when switching from a moving/loading state to non-moving/unloaded state,showing opposite behavior.The developed hydraulic drive mechanism provides a way for implementation of multi-pass local loading without auxiliary operation and extra heating.The results of the study provide a foundation for the industrial production of large-scale,complex components with reduced force requirement and low-energy consumption.
基金supported by the Major Research Development Program of Hubei Province,China(Grant Nos.2022BAA093 and 2022BAD163)the Open Research Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.SKLGME023008).
文摘With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at different temperatures in combination with real-time acoustic emission(AE)monitoring.The results show that the cumulative AE count increases stepwise with increasing cyclic stress.The peak frequency is concentrated primarily in the medium-frequency range,exhibiting a band distribution across low-,medium-,and high-frequency ranges.As the temperature increases,the proportion of low-frequency signals decreases from 14.32%to 5.76%,whereas the proportion of medium-frequency signals increases from 85.48%to 94.1%.The proportion of high-frequency signals remains relatively constant between 0.1%and 0.2%.The amplitude-count relationship of the AE signals demonstrates a strong negative power-law correlation.Furthermore,with increasing temperature,the negative power-law exponent of the amplitude gradually decreases,with the b value decreasing from 1.096 to 0.837 and the a value decreasing from 7.4871 to 6.6982.Under all four temperature conditions,the dominant failure mode in rock salt is tensile cracking.However,as the temperature increases,the proportion of tensile cracks decreases from 88.59%to 75.12%,whereas the proportion of shear cracks at 80℃is nearly double that at 20℃.This finding indicates that as the temperature increases,the ductility of the material increases,and the crack propagation mode shifts from tensile to shear.This research provides valuable insights for the design and stability assessment of salt cavern reservoirs for deep underground energy storage systems.
基金support provided by the National Natural Science Foundation of China(No.52274077)the Natural Science Foundation of Henan(No.242300421072)+2 种基金the Youth Elite Teachers Cultivation Program for Higher Education Institutions in Henan Province(No.2024GGJS036)the Funds for Distinguished Young Scholars of Henan Polytechnic University(No.J2023-3)the Young Core Teacher Funding Scheme of Henan Polytechnic University(No.2023XQG-09).
文摘This study examined non-uniform loading in goaf cantilever rock masses via testing,modeling,and mechanical analysis to solve instantaneous fracture and section buckling from mining abutment pressure.The study investigates the non-uniform load gradient effect on fracture characteristics,including load characteristics,fracture location,fracture distribution,and section roughness.A digital model for fracture interface buckling analysis was developed,elucidating the influence of non-uniform load gradients on Fracture Interface Curvature(FIC),Buckling Rate of Change(BRC),and Buckling Domain Field(BDF).The findings reveal that nonlinear tensile stress concentration and abrupt tensile-compressive-shear strain mutations under non-uniform loading are fundamental mechanisms driving fracture path buckling in cantilever rock mass structures.The buckling process of rock mass under non-uniform load can be divided into two stages:low load gradient and high gradient load.In the stage of low gradient load,the buckling behavior is mainly reflected in the compression-shear fracture of the edge.In the stage of high gradient load,a buckling band along the loading direction is gradually formed in the rock mass.These buckling principles establish a theoretical basis for accurately characterizing bearing fractures,fracture interface instability,and vibration sources within overlying cantilever rock masses in goaf.
基金supported by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety(KoFONS)using the financial resource granted by the Nuclear Safety and Security Commission(NSSC)of the Republic of Korea[RS-2025-02310881]the Korea Institute of Energy Technology Evaluation and Planning[KETEP]grant funded by the Ministry of Trade,Industry and Energy(MOTIE)[RS-2025-25447272].
文摘Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigates the effects of sheath(duct)implementation and confinement assumptions through nonlinear finite element analysis.Four modeling cases were defined,consisting of an explicit sheath without tendon-concrete confinement(S)and three no-sheath variants with different confinement levels(X,N,A).One-way beams and two-way panels were analyzed,and panel blast responses were validated against experimental results.In both beams and panels,average initial stress levels were similar across models,through local stress concentrations appeared when the sheath was modeled.Under blast loading,these local effects became critical,and the sheath-implemented model reproduced experimental behavior most accurately,whereas non-implemented models deviated.Reduced blast intensity diminished the differences among models,thereby reaffirming that sheath-induced localization and damage propagation are critical factors.These findings highlight the importance of explicit sheath implementation for realistic numerical assessment of unbonded PT structures under extreme loads.
基金supported by the National Natural Science Foundation with grant No.12374408。
文摘Air conditioning is a major energy-consuming component in buildings,and accurate air conditioning load forecasting is of great significance for maximizing energy utilization efficiency.However,the deep learning models currently used in the field of air conditioning load forecasting often suffer from issues such as distribution bias in load data and insufficient expression ability of nonlinear features in the model,which affect the accuracy of load forecasting.To address this,this paper proposes a novel load forecasting model.Firstly,the model employs the Dish-TS(DS)module to standardize the input window data through self-learning standardized parameters,thereby addressing the spatial intra-bias problem existing between data.Secondly,DS-Kansformer introduces Kolmogorov-Arnold Networks(KANs)to enhance the expression ability of nonlinear features.Finally,the output window is denormalized through the self-learning parameter of the DS module to restore the original distribution of the predicted data.In this paper,experiments were carried out based on the air-conditioning load dataset collected from a multi-functional comprehensive building,and the experimental results show that after adding the DS module,the Mean Absolute Error(MAE),Root Mean Square Error(RMSE),and R-squared(R^(2))of the model are 20.46%,34.44%,and 92.61%,respectively;after introducing KAN,the MAE,RMSE,and R^(2) are 22.81%,35.72%,and 92.05%,respectively;the model also exhibits high prediction accuracy after integrating the two modules(with RMSE,MAE,and R^(2) being 19.75%,34.05%,and 92.78%,respectively),outperforming common time series prediction models,confirming the reliability and efficiency of the model,which can provide reliable support for intelligent energy management in buildings.
基金supported by the Natural Science Foundation of China No.62303126the project Major Scientific and Technological Special Project of Guizhou Province([2024]014).
文摘This paper investigates the detection and mitigation of coordinated cyberattacks on Load Frequency Control(LFC)systems integrated with Battery Energy Storage Systems(BESS).As renewable energy sources gain greater penetration,power grids are becoming increasingly vulnerable to cyber threats,potentially leading to frequency instability and widespread disruptions.We model two significant attack vectors:load-altering attacks(LAAs)and false data injection attacks(FDIAs)that corrupt frequency measurements.These are analyzed for their impact on grid frequency stability in both linear and nonlinear LFC models,incorporating generation rate constraints and nonlinear loads.A coordinated attack strategy is presented,combining LAAs and FDIAs to achieve stealthiness by concealing frequency deviations from system operators,thereby maximizing disruption while evading traditional detection.To counteract these threats,we propose an Unknown Input Observer(UIO)-based detection framework for linear and nonlinear LFCs.The UIO is designed using linear matrix inequalities(LMIs)to estimate system states while isolating unknown attack inputs,enabling attack detection through monitoring measurement residuals against a predefined threshold.For mitigation,we leverage BESS capabilities with two adaptive strategies:dynamic mitigation for dynamic LAAs,which tunes BESS parameters to enhance the system’s stability margin and accelerate convergence to equilibrium;and staticmitigation for static LAAs and FDIAs.Simulations show that the UIO achieves high detection accuracy,with residuals exceeding thresholds promptly under coordinated attacks,even in nonlinear models.Mitigation strategies reduce frequency deviations by up to 80%compared to unmitigated cases,restoring stability within seconds.
基金financial and intellectual support provided by Queensland University of Technology(QUT)through its Higher Degree Research Program.
文摘The growing demands on global infrastructure highlight the critical need for durable and efficient pavement systems,particularly under the stress of repetitive heavy traffic loads.The use of geosynthetics within the pavement structure increases the load-carrying capacity of unbound pavement layers by providing lateral restraint,improving vertical stress distribution,and enhancing bearing capacity.Such reinforcement typically aims to either improve the service life of pavements or achieve equivalent performance with a reduced granular cover.Previous and ongoing research quantifies geosynthetic performance in pavement reinforcement using various testing methods.Among these,laboratory model box tests subjected to cyclic loading are pivotal,as they closely replicate real-world traffic conditions.Hence,these studies are essential for understanding how geosynthetics distribute loads and enhance pavement durability.This facilitates the development of optimized geosynthetic design and installation practices,accelerating the loading process to simulate years of traffic wear in a shorter period.This review discusses the improved rutting resistance of unbound pavements reinforced with geosynthetic materials,specifically drawing on data from cyclic plate load tests conducted on laboratory model boxes,as highlighted in the literature.Key variables such as optimum geosynthetic placement,geosynthetic material properties,performance of different geosynthetic materials and the effects of aperture shape and size on rutting resistance are discussed.Furthermore,the review assesses various predictive rutting models,analysing their applicability and accuracy in forecasting the rutting performance of geosynthetic-reinforced unbound pavements.This comprehensive literature review aids pavement engineers and researchers,in guiding the selection and design of geosynthetics to optimize pavement durability and functionality under repetitive traffic loads.
基金financially supported by the Swedish Transport Administration(Trafikverket)through the“Excellence Area 4”and FOI-BBT program(Grant Nos.BBT-2019-022 and BBT-TRV 2024/132497).
文摘Railway noise barriers are an essential piece of infrastructure for reducing noise propagation.However,these barriers experience aerodynamic loads generated by high-speed trains,leading to dynamic effects that may compromise their fatigue capacity.The most common structural design for railway noise barriers consists of vertical configurations of posts and panels.However,there have been few dynamic analyses of steel post/wood panel noise barriers under train-induced aerodynamic loads.This study used dynamic finite element analysis to assess the dynamic behavior of such noise barriers.Analysis of a 40-m-long noise barrier model and a triangular simplified load model,the latter of which effectively represented the detailed aerodynamic load,were first used to establish the model and input of the moving load during dynamic simulation.Then,the effects of different parameters on the dynamic response of the noise barrier were evaluated,including the damping ratio,the profile of the steel post,the span length of the panel,the barrier height,and the train speed.Gray relational analysis indicated that barrier height exhibited the highest correlations with the dynamic responses,followed by train speed,post profile,span length,and damping ratio.A reduction in the natural frequency and an increase in the train speed result in a higher peak response and more pronounced fluctuations between the nose and tail waves.The dynamic amplification factor(DAF)was found to be related to both the natural frequency and train speed.A model was proposed showing that the DAF significantly increases as the square of the natural frequency decreases and the cube of the train speed rises.
基金financially supported by the National Key R&D Program of China(2024YFC3012700)National Natural Science Foundation of China(12302499)+1 种基金Key Laboratory of Mountain Hazards and Engineering Resilience,Chinese Academy of Sciences(KLMHER-Z17,KLMHER-T07)National Natural Science Foundation of Fujian Province(Grant No.2024J08074).
文摘Frozen moraine soils are widely distributed across the Tianshan Mountains,the Qinghai-Tibetan Plateau,and other high-altitude regions.Engineering activities,particularly blasting,often induce degradation of the soil microstructure,compromising its mechanical integrity and increasing the risk of slope instability and rainfall-triggered debris flows-posing serious threats to infrastructure in cold regions.Previous studies have largely treated frozen soils as homogeneous continua,thereby overlooking key micro-scale processes such as ice-soil interaction,microcrack propagation,and particle breakage.In this study,the dynamic mechanical behavior and microstructural damage mechanisms of frozen moraine soil were systematically investigated under varying temperatures(−5℃,−15℃,and−25℃)and strain rates(50 s^(-1),70 s^(-1),and 90 s^(-1)).Results reveal that both temperature and strain rate significantly influence the dynamic stress-strain response.Energy absorption exhibits a three-stage pattern of increase,stabilization,and decline.At−25℃,increased ice brittleness reduces the peak energy absorption efficiency under impact.To capture the observed nonlinear behavior,a damage-based constitutive model was developed,incorporating coupled effects of impact-induced microcracking,ice-soil interfacial debonding,and particle fracture.The stochastic evolution of interfacial debonding and grain breakage was described using a Weibull statistical framework,linking microstructural deterioration to macroscopic response.The model shows strong agreement with experimental data and accurately simulates key parameters such as peak stress and energy absorption.These findings enhance the understanding of dynamic damage mechanisms in frozen soils and offer a computational tool for the safety assessment and hazard mitigation of engineering structures in cold,high-altitude environments.
基金supported by the National Science Fund for Excellent Young Scholars (32322044)the CQMU Program for Youth Innovation in Future Medicine (W0077)+1 种基金the Program for Scientific and Technological Innovation Leader of Chongqing (CQYC20220303655)the Young Scientists Fund of the National Natural Science Foundation of China (82301144)。
文摘Nanotechnology has provided thousands of novel nano-antimicrobials possessing features uncommon in clinically available antimicrobials.Here,nanocarriers loaded with conventional antimicrobials and responding to environmental changes upon entry into oral biofilms are reviewed.Supra-gingival biofilms are characterized by acidic pH,the presence of bacterial enzymes,and the development of hypoxia in deeper layers.Sub-gingival biofilms are slightly alkaline,with hypoxia occurring over their entire depth.Upon entering biofilms,negatively charged,pH-and/or hypoxia-responsive nanocarriers become positively charged.This charge reversal leads to electrostatic double-layer attraction between positively charged nanocarriers towards negatively charged,waterfilled channel walls in biofilms,enhancing their accumulation in a biofilm.Degradation of bacterial enzyme-responsive nanocarriers causes in-biofilm release of antimicrobial cargo,yielding higher local antimicrobial concentrations than can be achieved through their direct,oral administration without harming soft tissues.Enhanced antibiofilm activity after in-biofilm antimicrobial release from biofilm-responsive micelles and liposomes has been demonstrated in vitro towards single-species Streptococcus mutans and Staphylococcus aureus biofilms or in vivo using specific-pathogen-free rodents inoculated with selected pathogens.This preferential antibacterial activity regulated the microbial composition of ex vivo human oral biofilm towards a more healthy microbiome composition.Although clinical confirmation is limited,the potential benefits of stimuli-responsive,antimicrobial-loaded nanocarriers for oral biofilm control and microbiome restoration are worth further investigation towards clinical translation.
