Development of the intermittent energy is greatly promoted by change in energy, while consumption of large-scale intermittent energy is becoming a problem. With the development of smart grid technology, controllabilit...Development of the intermittent energy is greatly promoted by change in energy, while consumption of large-scale intermittent energy is becoming a problem. With the development of smart grid technology, controllability of load side resources is becoming more and more important. Based on the wave characteristics of wind power, this paper indicates that wind energy has continuous output characteristics on the hour-time scale. Through analysis on loads characteristic of industry, public facility and resident, this paper gets comprehensive response of load side resources. Considering characteristics of wind power output, combined with different load side resources and DR program, this paper suggests cooperation between wind power and load side resources on different time scales.展开更多
As the proportion of newenergy increases,the traditional cumulant method(CM)produces significant errorswhen performing probabilistic load flow(PLF)calculations with large-scale wind power integrated.Considering the wi...As the proportion of newenergy increases,the traditional cumulant method(CM)produces significant errorswhen performing probabilistic load flow(PLF)calculations with large-scale wind power integrated.Considering the wind speed correlation,a multi-scenario PLF calculation method that combines random sampling and segmented discrete wind farm power was proposed.Firstly,based on constructing discrete scenes of wind farms,the Nataf transform is used to handle the correlation between wind speeds.Then,the random sampling method determines the output probability of discrete wind power scenarios when wind speed exhibits correlation.Finally,the PLF calculation results of each scenario areweighted and superimposed following the total probability formula to obtain the final power flow calculation result.Verified in the IEEE standard node system,the absolute percent error(APE)for the mean and standard deviation(SD)of the node voltages and branch active power are all within 1%,and the average root mean square(AMSR)values of the probability curves are all less than 1%.展开更多
In contemporary power systems,delving into the flexible regulation potential of demand-side resources is of paramount significance for the efficient operation of power grids.This research puts forward an innovative mu...In contemporary power systems,delving into the flexible regulation potential of demand-side resources is of paramount significance for the efficient operation of power grids.This research puts forward an innovative multivariate flexible load aggregation control approach that takes dynamic demand response into full consideration.In the initial stage,using generalized time-domain aggregation modelling for a wide array of heterogeneous flexible loads,including temperature-controlled loads,electric vehicles,and energy storage devices,a novel calculation method for their maximum adjustable capacities is devised.Distinct from conventional methods,this newly developed approach enables more precise and adaptable quantification of the load-adjusting capabilities,thereby enhancing the accuracy and flexibility of demand-side resource management.Subsequently,an SSA-BiLSTM flexible load classification prediction model is established.This model represents an innovative application in the field,effectively combining the advantages of the Sparrow Search Algorithm(SSA)and the Bidirectional Long-Short-Term Memory(BiLSTM)neural network.Furthermore,a parallel Markov chain is introduced to evaluate the switching state transfer probability of flexible loads accurately.This integration allows for a more refined determination of the maximum response capacity range of the flexible load aggregator,significantly improving the precision of capacity assessment compared to existing methods.Finally,in consonance with the intra-day scheduling plan,a newly developed diffuse filling algorithm is implemented to control the activation times of flexible loads precisely,thus achieving real-time dynamic demand response.Through in-depth case analysis and comprehensive comparative studies,the effectiveness of the proposed method is convincingly validated.With its innovative techniques and enhanced performance,it is demonstrated that this method has the potential to substantially enhance the utilization efficiency of demand-side resources in power systems,providing a novel and effective solution for optimizing power grid operation and demand-side management.展开更多
Loess is susceptible to loading effects such as significant changes in strength and volume variation caused by loading and wetting.In this study,considering the different connection states of pore water and gas in loe...Loess is susceptible to loading effects such as significant changes in strength and volume variation caused by loading and wetting.In this study,considering the different connection states of pore water and gas in loess fabric,the gas phase closure case is incorporated into a unified form of the generalized effective stress framework,introducing a damage parameter considering the effects of closed pore gas.The loading effects of unsaturated loess under wide variations in saturation are described in a unified way,and the model performance is verified by corresponding stress and hydraulic path tests.The results indicated that the collapse response involves the initial void ratio of loess,and the coupled outwards motion of the loading-collapse(LC)yield surface under loading enhances its structural strength.Suction-enhanced yield stress requires a greater"tensile stress"to counteract its structural stability.The nucleation of bubbles at high saturation causes a decrease in yield stress.The loading effect exhibits a smaller collapse behavior when the influence of closed gas is considered,whereas the suction path does not cross the LC in the stress space under hydraulic action for the same parameters,which amplifies the influence of closed gas on loess deformation.展开更多
Background With the development of the Internet,the topology optimization of wireless sensor networks has received increasing attention.However,traditional optimization methods often overlook the energy imbalance caus...Background With the development of the Internet,the topology optimization of wireless sensor networks has received increasing attention.However,traditional optimization methods often overlook the energy imbalance caused by node loads,which affects network performance.Methods To improve the overall performance and efficiency of wireless sensor networks,a new method for optimizing the wireless sensor network topology based on K-means clustering and firefly algorithms is proposed.The K-means clustering algorithm partitions nodes by minimizing the within-cluster variance,while the firefly algorithm is an optimization algorithm based on swarm intelligence that simulates the flashing interaction between fireflies to guide the search process.The proposed method first introduces the K-means clustering algorithm to cluster nodes and then introduces a firefly algorithm to dynamically adjust the nodes.Results The results showed that the average clustering accuracies in the Wine and Iris data sets were 86.59%and 94.55%,respectively,demonstrating good clustering performance.When calculating the node mortality rate and network load balancing standard deviation,the proposed algorithm showed dead nodes at approximately 50 iterations,with an average load balancing standard deviation of 1.7×10^(4),proving its contribution to extending the network lifespan.Conclusions This demonstrates the superiority of the proposed algorithm in significantly improving the energy efficiency and load balancing of wireless sensor networks to extend the network lifespan.The research results indicate that wireless sensor networks have theoretical and practical significance in fields such as monitoring,healthcare,and agriculture.展开更多
The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,th...The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,this bio-inspired design demonstrates reduced penetration resistance and enhanced pull-out capacity due to the anisotropic shear behaviors of its sidewall.To investigate the shear behavior of the bio-inspired sidewall under pull-out load,direct shear tests were conducted between the bio-inspired surface and sand.The research demonstrates that the interface shear strength of the bio-inspired surface significantly surpasses that of the smooth surface due to interlocking effects.Additionally,the interface shear strength correlates with the aspect ratio of the bio-inspired surface,shear angle,and particle diameter distribution,with values increasing as the uniformity coefficient Cudecreases,while initially increasing and subsequently decreasing with increases in both aspect ratio and shear angle.The ratio between the interface friction angleδand internal friction angle δ_(s) defines the interface effect factor k.For the bio-inspired surface,the interface effect factor k varies with shear angleβ,ranging from 0.9 to 1.12.The peak value occurs at a shear angleβof 60°,substantially exceeding that of the smooth surface.A method for calculating the relative roughness R_(N) is employed to evaluate the interface roughness of the bio-inspired surface,taking into account scale dimension and particle diameter distribution effects.展开更多
Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation...Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation of rectangular jacked pipes and the distribution of the earth pressure on jacked pipes,we present an analytical solution for predicting the vertical earth pressure on deep-buried rectangular pipe jacking tunnels,incorporating the tunnelling-induced ground loss distribution.Our proposed analytical model consists of the upper multi-layer parabolic soil arch and the lower friction arch.The key parameters(i.e.,width and height of friction arch B and height of parabolic soil arch H 1)are determined according to the existing research,and an analytical solution for K l is derived based on the distribution characteristics of the principal stress rotation angle.With consideration for the transition effect of the mechanical characteristics of the parabolic arch zone,an analytical solution for soil load transfer is derived.The prediction results of our analytical solution are compared with tests and simulation results to validate the effectiveness of the proposed analytical solution.Finally,the effects of different parameters on the soil pressure are discussed.展开更多
To facilitate the coordinated and large-scale participation of residential flexible loads in demand response(DR),a load aggregator(LA)can integrate these loads for scheduling.In this study,a residential DR optimizatio...To facilitate the coordinated and large-scale participation of residential flexible loads in demand response(DR),a load aggregator(LA)can integrate these loads for scheduling.In this study,a residential DR optimization scheduling strategy was formulated considering the participation of flexible loads in DR.First,based on the operational characteristics of flexible loads such as electric vehicles,air conditioners,and dishwashers,their DR participation,the base to calculate the compensation price to users,was determined by considering these loads as virtual energy storage.It was quantified based on the state of virtual energy storage during each time slot.Second,flexible loads were clustered using the K-means algorithm,considering the typical operational and behavioral characteristics as the cluster centroid.Finally,the LA scheduling strategy was implemented by introducing a DR mechanism based on the directrix load.The simulation results demonstrate that the proposed DR approach can effectively reduce peak loads and fill valleys,thereby improving the load management performance.展开更多
This study investigated the sidewall rockburst characteristics of highly stressed circular tunnel subjected to impact loads resulting from rock blasting or other mining-related dynamic disturbances,aiming at exploring...This study investigated the sidewall rockburst characteristics of highly stressed circular tunnel subjected to impact loads resulting from rock blasting or other mining-related dynamic disturbances,aiming at exploring the influence of vertical prestress and dynamic load on sidewall rockburst.Using a biaxial Hopkinson pressure bar(BHPB)system,we studied the sidewall rockburst of a circular tunnel by applying various prestresses(horizontal and vertical static stresses)to a sand prefabricated circular hole specimen,followed by impact loads.The real-time process and strain field of the sidewall rockburst around the specimen were tracked by the high-speed camera and digital image correlation(DIC).The tests reveal that the sidewall rockburst process can be summarized as:calm stage,slab buckling and spalling stage,rock slabs ejection stage,and V-shaped notch formation stage.Furthermore,the sidewall rockbursts exhibit typical dynamic tensile failure.The mechanism of sidewall rockburst under the coupled static-impact loads was summarized,i.e.the static prestress determines the initial stress and strain distribution,and the vertical prestress influences the affected range and strain values of the strain concentration zone;the impact load disrupts the original static stress equilibrium,inducing alterations in the stress and strain of the surrounding rock and triggering sidewall rockburst.展开更多
With the frequent occurrence of global warming and extreme severe weather,the transition of energy to cleaner,and with lower carbon has gradually become a consensus.Microgrids can integrate multiple energy sources and...With the frequent occurrence of global warming and extreme severe weather,the transition of energy to cleaner,and with lower carbon has gradually become a consensus.Microgrids can integrate multiple energy sources and consume renewable energy locally.The amount of pollutants emitted during the operation of the microgrids become an important issue to be considered.This study proposes an optimal day-ahead scheduling strategy of microgrid considering regional pollution and potential load curtailment.First,considering the operating characteristics of microgrids in islanded and grid-connected operation modes,this study proposes a regional pollution index(RPI)to quantify the impact of pollutants emitted from microgrid on the environment,and further proposes a penalty mechanism based on the RPI to reduce the microgrid’s utilization on non-clean power supplies.Second,considering the benefits of microgrid as the operating entity,utilizing a direct load control(DLC)enables microgrid to enhance power transfer capabilities to the grid under the penalty mechanism based on RPI.Finally,an optimal day-ahead scheduling strategy which considers both the load curtailment potential of curtailable loads and RPI is proposed,and the results show that the proposed optimal day-ahead scheduling strategy can effectively inspire the curtailment potential of curtailable loads in the microgrid,reducing pollutant emissions from the microgrid.展开更多
To further investigate the forming mechanism and springback characteristics of strips under multi-square punch forming (MSPF) considering partial-unloading effects, a series of concave form ing tests of strips are con...To further investigate the forming mechanism and springback characteristics of strips under multi-square punch forming (MSPF) considering partial-unloading effects, a series of concave form ing tests of strips are conducted on the MSPF machine. This paper aims to reveal the physical mecha nism of the elastic-plastic deformation in the MSPF process considering the effect of the forming ap proaches, and derive appropriate mathematical interpretations. The theoretical model is firstly estab lished to analyse the concave forming mechanism and springback characteristics of the strip, and its accuracy is then validated by experimental data. The forming history and load evolutions are depicted to explore the required forming capacity through the proposed analytical method. Besides, the paramet ric studies are carried out to discuss their effects on the springback of the strip. The results suggest that the deformation paths of the strip are influenced by the forming approach, and the springback of the strip in convex forming is larger than that in concave forming.展开更多
In fossil energy pollution is serious and the“double carbon”goal is being promoted,as a symbol of fresh energy in the electrical system,solar and wind power have an increasing installed capacity,only conventional un...In fossil energy pollution is serious and the“double carbon”goal is being promoted,as a symbol of fresh energy in the electrical system,solar and wind power have an increasing installed capacity,only conventional units obviously can not solve the new energy as the main body of the scheduling problem.To enhance the systemscheduling ability,based on the participation of thermal power units,incorporate the high energy-carrying load of electro-melting magnesiuminto the regulation object,and consider the effects on the wind unpredictability of the power.Firstly,the operating characteristics of high energy load and wind power are analyzed,and the principle of the participation of electrofusedmagnesiumhigh energy-carrying loads in the elimination of obstructedwind power is studied.Second,a two-layer optimization model is suggested,with the objective function being the largest amount of wind power consumed and the lowest possible cost of system operation.In the upper model,the high energy-carrying load regulates the blocked wind power,and in the lower model,the second-order cone approximation algorithm is used to solve the optimizationmodelwithwind power uncertainty,so that a two-layer optimizationmodel that takes into account the regulation of the high energy-carrying load of the electrofused magnesium and the uncertainty of the wind power is established.Finally,the model is solved using Gurobi,and the results of the simulation demonstrate that the suggested model may successfully lower wind abandonment,lower system operation costs,increase the accuracy of day-ahead scheduling,and lower the final product error of the thermal electricity unit.展开更多
Reasonable distribution of braking force is a factor for a smooth,safe,and comfortable braking of trains.A dynamic optimal allocation strategy of electric-air braking force is proposed in this paper to solve the probl...Reasonable distribution of braking force is a factor for a smooth,safe,and comfortable braking of trains.A dynamic optimal allocation strategy of electric-air braking force is proposed in this paper to solve the problem of the lack of consideration of adhesion difference of train wheelsets in the existing high-speed train electric-air braking force optimal allocation strategies.In this method,the braking strategy gives priority to the use of electric braking force.The force model of a single train in the braking process is analyzed to calculate the change of adhesion between the wheel and rail of each wheelset after axle load transfer,and then the adhesion of the train is estimated in real time.Next,with the goal of maximizing the total adhesion utilization ratio of trailer/motor vehicles,a linear programming distribution function is constructed.The proportional coefficient of adhesion utilization ratio of each train and the application upper limit of braking force in the function is updated according to the change time point of wheelset adhesion.Finally,the braking force is dynamically allocated.The simulation results of Matlab/Simulink show that the proposed algorithm not only uses the different adhesion limits of each trailer to reduce the total amount of braking force undertaken by the motor vehicle,but also considers the adhesion difference of each wheelset.The strategy can effectively reduce the risk and time of motor vehicles during the braking process and improve the stability of the train braking.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
Non-seismically designed(NSD)beam-column joints are susceptible to joint shear failure under seismic loads.Although significant research is available on the seismic behavior of such joints of planar frames,the informa...Non-seismically designed(NSD)beam-column joints are susceptible to joint shear failure under seismic loads.Although significant research is available on the seismic behavior of such joints of planar frames,the information on the seismic behavior of joints of space frames(3D joints)is insufficient.The 3D joints are subjected to bi-directional excitation,which results in an interaction between the shear strength obtained for the joint in the two orthogonal directions separately.The bi-directional seismic behavior of corner reinforced concrete(RC)joints is the focus of this study.First,a detailed finite element(FE)model using the FE software Abaqus,is developed and validated using the test results from the literature.The validated modeling procedure is used to conduct a parametric study to investigate the influence of different parameters such as concrete strength,dimensions of main and transverse beams framing into the joint,presence or absence of a slab,axial load ratio and loading direction on the seismic behavior of joints.By subjecting the models to different combinations of loads on the beams along perpendicular directions,the interaction of the joint shear strength in two orthogonal directions is studied.The comparison of the interaction curves of the joints obtained from the numerical study with a quadratic(circular)interaction curve indicates that in a majority of cases,the quadratic interaction model can represent the strength interaction diagrams of RC beam to column connections with governing joint shear failure reasonably well.展开更多
A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that th...A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior.展开更多
More than 200 years after Parkinson's disease was first described by the English surgeon whose name would eventually be given to the condition,available treatments remain purely symptomatic,leaving a critical unme...More than 200 years after Parkinson's disease was first described by the English surgeon whose name would eventually be given to the condition,available treatments remain purely symptomatic,leaving a critical unmet clinical need for a diseasemodifying therapy.展开更多
In rock drilling and blasting,the misfire of electronic detonators will not only affect the rock fragmentation result but also bring serious potential safety hazards to engineering construction.An accurate and compreh...In rock drilling and blasting,the misfire of electronic detonators will not only affect the rock fragmentation result but also bring serious potential safety hazards to engineering construction.An accurate and comprehensive understanding of the failure mechanisms of electronic detonators subjected to impact loading is of great significance to the reliability design and field safety use of electronic detonators.The spatial distribution characteristics and failure modes of misfired electronic detonators under different application scenarios are statistically analysed.The results show that under high impact loads,electronic detonators will experience failure phenomena such as rupture of the fuse head,fracture of the bridge wire,falling off of the solder joint,chip module damage and insufficient initiation energy after deformation.The lack of impact resistance is the primary cause of misfire of electronic detonators.Combined with the underwater impact resistance test and the impact load test in the adjacent blasthole on site,the formulas of the impact failure probability of the electronic detonator under different stress‒strength distribution curves are deduced.The test and evaluation method of the impact resistance of electronic detonators based on stress‒strength interference theory is proposed.Furthermore,the impact failure model of electronic detonators considering the strength degradation effect under repeated random loads is established.On this basis,the failure mechanism of electronic detonators under different application environments,such as open-pit blasting and underground blasting,is revealed,which provides scientific theory and methods for the reliability analysis,design and type selection of electronic detonators in rock drilling and blasting.展开更多
Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including at...Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including atmospheric, hydrological, and nontidal ocean loading. Continuous improvements in the accuracy of surface mass loading products, performance of Earth models, and precise data-processing technologies have significantly advanced research on the effects of environmental loading on nonlinear variations in GNSS coordinate time series. However, owing to theoretical limitations, the lack of high spatiotemporal resolution surface mass observations, and the coupling of GNSS technology-related systematic errors, environmental loading and nonlinear GNSS reference station displacements remain inconsistent. The applicability and capability of these loading products across different regions also require further evaluation. This paper outlines methods for modeling environmental loading, surface mass loading products, and service organizations. In addition, it summarizes recent advances in applying environmental loading to address nonlinear variations in global and regional GNSS coordinate time series. Moreover, the scientific questions of existing studies are summarized, and insights into future research directions are provided. The complex nonlinear motion of reference stations is a major factor limiting the accuracy of the current terrestrial reference frame. Further refining the environmental load modeling method, establishing a surface mass distribution model with high spatiotemporal resolution and reliability, exploring other environmental load factors such as ice sheet and artificial mass-change effects, and developing an optimal data-processing model and strategy for reprocessing global reference station data consistently could contribute to the development of a millimeter-level nonlinear motion model for GNSS reference stations with actual physical significance and provide theoretical support for establishing a terrestrial reference frame with 1 mm accuracy by 2050.展开更多
Accurate prediction of electric vehicle(EV)charging loads is a foundational step in the establishment of expressway charging infrastructures.This study introduces an approach to enhance the precision of expressway EV ...Accurate prediction of electric vehicle(EV)charging loads is a foundational step in the establishment of expressway charging infrastructures.This study introduces an approach to enhance the precision of expressway EV charging load predictions.The method considers both the battery dynamic state-of-charge(SOC)and user charging decisions.Expressway network nodes were first extracted using the open Gaode Map API to establish a model that incorporates the expressway network and traffic flow fea-tures.A Gaussian mixture model is then employed to construct a SOC distribution model for mixed traffic flow.An innovative SOC dynamic translation model is then introduced to capture the dynamic characteristics of traffic flow SOC values.Based on this foun-dation,an EV charging decision model was developed which considers expressway node distinctions.EV travel characteristics are extracted from the NHTS2017 datasets to assist in constructing the model.Differentiated decision-making is achieved by utilizing improved Lognormal and Sigmoid functions.Finally,the proposed method is applied to a case study of the Lian-Huo expressway.An analysis of EV charging power converges with historical data and shows that the method accurately predicts the charging loads of EVs on expressways,thus revealing the efficacy of the proposed approach in predicting EV charging dynamics under expressway scenarios.展开更多
文摘Development of the intermittent energy is greatly promoted by change in energy, while consumption of large-scale intermittent energy is becoming a problem. With the development of smart grid technology, controllability of load side resources is becoming more and more important. Based on the wave characteristics of wind power, this paper indicates that wind energy has continuous output characteristics on the hour-time scale. Through analysis on loads characteristic of industry, public facility and resident, this paper gets comprehensive response of load side resources. Considering characteristics of wind power output, combined with different load side resources and DR program, this paper suggests cooperation between wind power and load side resources on different time scales.
基金supported by Basic Science Research Program through the National Natural Science Foundation of China(Grant No.61867003).
文摘As the proportion of newenergy increases,the traditional cumulant method(CM)produces significant errorswhen performing probabilistic load flow(PLF)calculations with large-scale wind power integrated.Considering the wind speed correlation,a multi-scenario PLF calculation method that combines random sampling and segmented discrete wind farm power was proposed.Firstly,based on constructing discrete scenes of wind farms,the Nataf transform is used to handle the correlation between wind speeds.Then,the random sampling method determines the output probability of discrete wind power scenarios when wind speed exhibits correlation.Finally,the PLF calculation results of each scenario areweighted and superimposed following the total probability formula to obtain the final power flow calculation result.Verified in the IEEE standard node system,the absolute percent error(APE)for the mean and standard deviation(SD)of the node voltages and branch active power are all within 1%,and the average root mean square(AMSR)values of the probability curves are all less than 1%.
基金the Science and Technology Project of State Grid Shanxi Electric Power Co.,Ltd.,with the project number 52051L240001.
文摘In contemporary power systems,delving into the flexible regulation potential of demand-side resources is of paramount significance for the efficient operation of power grids.This research puts forward an innovative multivariate flexible load aggregation control approach that takes dynamic demand response into full consideration.In the initial stage,using generalized time-domain aggregation modelling for a wide array of heterogeneous flexible loads,including temperature-controlled loads,electric vehicles,and energy storage devices,a novel calculation method for their maximum adjustable capacities is devised.Distinct from conventional methods,this newly developed approach enables more precise and adaptable quantification of the load-adjusting capabilities,thereby enhancing the accuracy and flexibility of demand-side resource management.Subsequently,an SSA-BiLSTM flexible load classification prediction model is established.This model represents an innovative application in the field,effectively combining the advantages of the Sparrow Search Algorithm(SSA)and the Bidirectional Long-Short-Term Memory(BiLSTM)neural network.Furthermore,a parallel Markov chain is introduced to evaluate the switching state transfer probability of flexible loads accurately.This integration allows for a more refined determination of the maximum response capacity range of the flexible load aggregator,significantly improving the precision of capacity assessment compared to existing methods.Finally,in consonance with the intra-day scheduling plan,a newly developed diffuse filling algorithm is implemented to control the activation times of flexible loads precisely,thus achieving real-time dynamic demand response.Through in-depth case analysis and comprehensive comparative studies,the effectiveness of the proposed method is convincingly validated.With its innovative techniques and enhanced performance,it is demonstrated that this method has the potential to substantially enhance the utilization efficiency of demand-side resources in power systems,providing a novel and effective solution for optimizing power grid operation and demand-side management.
基金funded by the National Natural Science Foundation of China (Grant Nos.42230712,42472357)the China Postdoctoral Science Foundation (Grant No.2023MD734211).
文摘Loess is susceptible to loading effects such as significant changes in strength and volume variation caused by loading and wetting.In this study,considering the different connection states of pore water and gas in loess fabric,the gas phase closure case is incorporated into a unified form of the generalized effective stress framework,introducing a damage parameter considering the effects of closed pore gas.The loading effects of unsaturated loess under wide variations in saturation are described in a unified way,and the model performance is verified by corresponding stress and hydraulic path tests.The results indicated that the collapse response involves the initial void ratio of loess,and the coupled outwards motion of the loading-collapse(LC)yield surface under loading enhances its structural strength.Suction-enhanced yield stress requires a greater"tensile stress"to counteract its structural stability.The nucleation of bubbles at high saturation causes a decrease in yield stress.The loading effect exhibits a smaller collapse behavior when the influence of closed gas is considered,whereas the suction path does not cross the LC in the stress space under hydraulic action for the same parameters,which amplifies the influence of closed gas on loess deformation.
基金Supported by 2021 Zhanjiang University of Science and Technology"Brand Enhancement Plan"Project:Network Series Course Teaching Team(PPJH202102JXTD)2022 Zhanjiang University of Science and Technology"Brand Enhancement Plan"Project:Network Engineering(PPJHKCSZ-2022301)+1 种基金2023 Zhanjiang Science and Technology Bureau Project:Design and Simulation of Zhanjiang Mangrove Wetland Monitoring Network System(2023B01017)2022 Zhanjiang University of Science and Technology Quality Engineering Project:Audiovisual Language Teaching and Research Office(ZLGC202203).
文摘Background With the development of the Internet,the topology optimization of wireless sensor networks has received increasing attention.However,traditional optimization methods often overlook the energy imbalance caused by node loads,which affects network performance.Methods To improve the overall performance and efficiency of wireless sensor networks,a new method for optimizing the wireless sensor network topology based on K-means clustering and firefly algorithms is proposed.The K-means clustering algorithm partitions nodes by minimizing the within-cluster variance,while the firefly algorithm is an optimization algorithm based on swarm intelligence that simulates the flashing interaction between fireflies to guide the search process.The proposed method first introduces the K-means clustering algorithm to cluster nodes and then introduces a firefly algorithm to dynamically adjust the nodes.Results The results showed that the average clustering accuracies in the Wine and Iris data sets were 86.59%and 94.55%,respectively,demonstrating good clustering performance.When calculating the node mortality rate and network load balancing standard deviation,the proposed algorithm showed dead nodes at approximately 50 iterations,with an average load balancing standard deviation of 1.7×10^(4),proving its contribution to extending the network lifespan.Conclusions This demonstrates the superiority of the proposed algorithm in significantly improving the energy efficiency and load balancing of wireless sensor networks to extend the network lifespan.The research results indicate that wireless sensor networks have theoretical and practical significance in fields such as monitoring,healthcare,and agriculture.
基金supported by the National Natural Science Foundation of China(Grant Nos.52371301 and 52471289)。
文摘The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,this bio-inspired design demonstrates reduced penetration resistance and enhanced pull-out capacity due to the anisotropic shear behaviors of its sidewall.To investigate the shear behavior of the bio-inspired sidewall under pull-out load,direct shear tests were conducted between the bio-inspired surface and sand.The research demonstrates that the interface shear strength of the bio-inspired surface significantly surpasses that of the smooth surface due to interlocking effects.Additionally,the interface shear strength correlates with the aspect ratio of the bio-inspired surface,shear angle,and particle diameter distribution,with values increasing as the uniformity coefficient Cudecreases,while initially increasing and subsequently decreasing with increases in both aspect ratio and shear angle.The ratio between the interface friction angleδand internal friction angle δ_(s) defines the interface effect factor k.For the bio-inspired surface,the interface effect factor k varies with shear angleβ,ranging from 0.9 to 1.12.The peak value occurs at a shear angleβof 60°,substantially exceeding that of the smooth surface.A method for calculating the relative roughness R_(N) is employed to evaluate the interface roughness of the bio-inspired surface,taking into account scale dimension and particle diameter distribution effects.
基金Project(2022YJS073)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2024YFE0198500)supported by the National Key Research and Development Program of China:Intergovernmental International Science and Technology Innovation CooperationProject(U2469207)supported by the National Natural Science Foundation Railway Innovation and Development Joint Fund Project,China。
文摘Determining earth pressure on jacked pipes is essential for ensuring lining safety and calculating jacking force,especially for deep-buried pipes.To better reflect the soil arching effect resulting from the excavation of rectangular jacked pipes and the distribution of the earth pressure on jacked pipes,we present an analytical solution for predicting the vertical earth pressure on deep-buried rectangular pipe jacking tunnels,incorporating the tunnelling-induced ground loss distribution.Our proposed analytical model consists of the upper multi-layer parabolic soil arch and the lower friction arch.The key parameters(i.e.,width and height of friction arch B and height of parabolic soil arch H 1)are determined according to the existing research,and an analytical solution for K l is derived based on the distribution characteristics of the principal stress rotation angle.With consideration for the transition effect of the mechanical characteristics of the parabolic arch zone,an analytical solution for soil load transfer is derived.The prediction results of our analytical solution are compared with tests and simulation results to validate the effectiveness of the proposed analytical solution.Finally,the effects of different parameters on the soil pressure are discussed.
基金supported by the Basic Science(Natural Science)Research Project of Jiangsu Higher Education Institutions(No.23KJB470020)the Natural Science Foundation of Jiangsu Province(Youth Fund)(No.BK20230384)。
文摘To facilitate the coordinated and large-scale participation of residential flexible loads in demand response(DR),a load aggregator(LA)can integrate these loads for scheduling.In this study,a residential DR optimization scheduling strategy was formulated considering the participation of flexible loads in DR.First,based on the operational characteristics of flexible loads such as electric vehicles,air conditioners,and dishwashers,their DR participation,the base to calculate the compensation price to users,was determined by considering these loads as virtual energy storage.It was quantified based on the state of virtual energy storage during each time slot.Second,flexible loads were clustered using the K-means algorithm,considering the typical operational and behavioral characteristics as the cluster centroid.Finally,the LA scheduling strategy was implemented by introducing a DR mechanism based on the directrix load.The simulation results demonstrate that the proposed DR approach can effectively reduce peak loads and fill valleys,thereby improving the load management performance.
基金supported by the National Natural Science Foundation of China(Grant No.42077244).
文摘This study investigated the sidewall rockburst characteristics of highly stressed circular tunnel subjected to impact loads resulting from rock blasting or other mining-related dynamic disturbances,aiming at exploring the influence of vertical prestress and dynamic load on sidewall rockburst.Using a biaxial Hopkinson pressure bar(BHPB)system,we studied the sidewall rockburst of a circular tunnel by applying various prestresses(horizontal and vertical static stresses)to a sand prefabricated circular hole specimen,followed by impact loads.The real-time process and strain field of the sidewall rockburst around the specimen were tracked by the high-speed camera and digital image correlation(DIC).The tests reveal that the sidewall rockburst process can be summarized as:calm stage,slab buckling and spalling stage,rock slabs ejection stage,and V-shaped notch formation stage.Furthermore,the sidewall rockbursts exhibit typical dynamic tensile failure.The mechanism of sidewall rockburst under the coupled static-impact loads was summarized,i.e.the static prestress determines the initial stress and strain distribution,and the vertical prestress influences the affected range and strain values of the strain concentration zone;the impact load disrupts the original static stress equilibrium,inducing alterations in the stress and strain of the surrounding rock and triggering sidewall rockburst.
基金Anhui Provincial Natural Science Foundation (No. 2208085UD07)National Natural Science Foundation of China (52377089).
文摘With the frequent occurrence of global warming and extreme severe weather,the transition of energy to cleaner,and with lower carbon has gradually become a consensus.Microgrids can integrate multiple energy sources and consume renewable energy locally.The amount of pollutants emitted during the operation of the microgrids become an important issue to be considered.This study proposes an optimal day-ahead scheduling strategy of microgrid considering regional pollution and potential load curtailment.First,considering the operating characteristics of microgrids in islanded and grid-connected operation modes,this study proposes a regional pollution index(RPI)to quantify the impact of pollutants emitted from microgrid on the environment,and further proposes a penalty mechanism based on the RPI to reduce the microgrid’s utilization on non-clean power supplies.Second,considering the benefits of microgrid as the operating entity,utilizing a direct load control(DLC)enables microgrid to enhance power transfer capabilities to the grid under the penalty mechanism based on RPI.Finally,an optimal day-ahead scheduling strategy which considers both the load curtailment potential of curtailable loads and RPI is proposed,and the results show that the proposed optimal day-ahead scheduling strategy can effectively inspire the curtailment potential of curtailable loads in the microgrid,reducing pollutant emissions from the microgrid.
文摘To further investigate the forming mechanism and springback characteristics of strips under multi-square punch forming (MSPF) considering partial-unloading effects, a series of concave form ing tests of strips are conducted on the MSPF machine. This paper aims to reveal the physical mecha nism of the elastic-plastic deformation in the MSPF process considering the effect of the forming ap proaches, and derive appropriate mathematical interpretations. The theoretical model is firstly estab lished to analyse the concave forming mechanism and springback characteristics of the strip, and its accuracy is then validated by experimental data. The forming history and load evolutions are depicted to explore the required forming capacity through the proposed analytical method. Besides, the paramet ric studies are carried out to discuss their effects on the springback of the strip. The results suggest that the deformation paths of the strip are influenced by the forming approach, and the springback of the strip in convex forming is larger than that in concave forming.
基金funded by the National Key R&D Program of China,Grant Number 2019YFB1505400.
文摘In fossil energy pollution is serious and the“double carbon”goal is being promoted,as a symbol of fresh energy in the electrical system,solar and wind power have an increasing installed capacity,only conventional units obviously can not solve the new energy as the main body of the scheduling problem.To enhance the systemscheduling ability,based on the participation of thermal power units,incorporate the high energy-carrying load of electro-melting magnesiuminto the regulation object,and consider the effects on the wind unpredictability of the power.Firstly,the operating characteristics of high energy load and wind power are analyzed,and the principle of the participation of electrofusedmagnesiumhigh energy-carrying loads in the elimination of obstructedwind power is studied.Second,a two-layer optimization model is suggested,with the objective function being the largest amount of wind power consumed and the lowest possible cost of system operation.In the upper model,the high energy-carrying load regulates the blocked wind power,and in the lower model,the second-order cone approximation algorithm is used to solve the optimizationmodelwithwind power uncertainty,so that a two-layer optimizationmodel that takes into account the regulation of the high energy-carrying load of the electrofused magnesium and the uncertainty of the wind power is established.Finally,the model is solved using Gurobi,and the results of the simulation demonstrate that the suggested model may successfully lower wind abandonment,lower system operation costs,increase the accuracy of day-ahead scheduling,and lower the final product error of the thermal electricity unit.
基金supported by the National Natural Science Foundation of China(Grant Nos.62173137,52172403,62303178).
文摘Reasonable distribution of braking force is a factor for a smooth,safe,and comfortable braking of trains.A dynamic optimal allocation strategy of electric-air braking force is proposed in this paper to solve the problem of the lack of consideration of adhesion difference of train wheelsets in the existing high-speed train electric-air braking force optimal allocation strategies.In this method,the braking strategy gives priority to the use of electric braking force.The force model of a single train in the braking process is analyzed to calculate the change of adhesion between the wheel and rail of each wheelset after axle load transfer,and then the adhesion of the train is estimated in real time.Next,with the goal of maximizing the total adhesion utilization ratio of trailer/motor vehicles,a linear programming distribution function is constructed.The proportional coefficient of adhesion utilization ratio of each train and the application upper limit of braking force in the function is updated according to the change time point of wheelset adhesion.Finally,the braking force is dynamically allocated.The simulation results of Matlab/Simulink show that the proposed algorithm not only uses the different adhesion limits of each trailer to reduce the total amount of braking force undertaken by the motor vehicle,but also considers the adhesion difference of each wheelset.The strategy can effectively reduce the risk and time of motor vehicles during the braking process and improve the stability of the train braking.
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.
文摘Non-seismically designed(NSD)beam-column joints are susceptible to joint shear failure under seismic loads.Although significant research is available on the seismic behavior of such joints of planar frames,the information on the seismic behavior of joints of space frames(3D joints)is insufficient.The 3D joints are subjected to bi-directional excitation,which results in an interaction between the shear strength obtained for the joint in the two orthogonal directions separately.The bi-directional seismic behavior of corner reinforced concrete(RC)joints is the focus of this study.First,a detailed finite element(FE)model using the FE software Abaqus,is developed and validated using the test results from the literature.The validated modeling procedure is used to conduct a parametric study to investigate the influence of different parameters such as concrete strength,dimensions of main and transverse beams framing into the joint,presence or absence of a slab,axial load ratio and loading direction on the seismic behavior of joints.By subjecting the models to different combinations of loads on the beams along perpendicular directions,the interaction of the joint shear strength in two orthogonal directions is studied.The comparison of the interaction curves of the joints obtained from the numerical study with a quadratic(circular)interaction curve indicates that in a majority of cases,the quadratic interaction model can represent the strength interaction diagrams of RC beam to column connections with governing joint shear failure reasonably well.
基金financially supported by the National Natural Science Foundation of China(Grant No.42172292)Taishan Scholars Project Special Funding,and Shandong Energy Group(Grant No.SNKJ 2022A01-R26).
文摘A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior.
基金funded by The Michael J.Fox Foundation for Parkinson’s Research(grant numbers:17244 and 023410)Science Foundation Ireland(grant number:19/FFP/6554)(to ED)。
文摘More than 200 years after Parkinson's disease was first described by the English surgeon whose name would eventually be given to the condition,available treatments remain purely symptomatic,leaving a critical unmet clinical need for a diseasemodifying therapy.
基金supported by the Chongqing Youth Talent Support Program(Cstc2022ycjh-bgzxm0079)the Chinese National Natural Science Foundation(52379128,51979152)+2 种基金Science Fund for Distinguished Young Scholars of Hubei Proivnce(2023AFA048)Educational Commission of Hubei Province of China(T2020005)the Young Top-notch Talent Cultivation Program of Hubei Province.
文摘In rock drilling and blasting,the misfire of electronic detonators will not only affect the rock fragmentation result but also bring serious potential safety hazards to engineering construction.An accurate and comprehensive understanding of the failure mechanisms of electronic detonators subjected to impact loading is of great significance to the reliability design and field safety use of electronic detonators.The spatial distribution characteristics and failure modes of misfired electronic detonators under different application scenarios are statistically analysed.The results show that under high impact loads,electronic detonators will experience failure phenomena such as rupture of the fuse head,fracture of the bridge wire,falling off of the solder joint,chip module damage and insufficient initiation energy after deformation.The lack of impact resistance is the primary cause of misfire of electronic detonators.Combined with the underwater impact resistance test and the impact load test in the adjacent blasthole on site,the formulas of the impact failure probability of the electronic detonator under different stress‒strength distribution curves are deduced.The test and evaluation method of the impact resistance of electronic detonators based on stress‒strength interference theory is proposed.Furthermore,the impact failure model of electronic detonators considering the strength degradation effect under repeated random loads is established.On this basis,the failure mechanism of electronic detonators under different application environments,such as open-pit blasting and underground blasting,is revealed,which provides scientific theory and methods for the reliability analysis,design and type selection of electronic detonators in rock drilling and blasting.
基金supported by the Basic Science Center Project of the National Natural Science Foundation of China(42388102)the National Natural Science Foundation of China(42174030)+2 种基金the Special Fund of Hubei Luojia Laboratory(220100020)the Major Science and Technology Program for Hubei Province(2022AAA002)the Fundamental Research Funds for the Central Universities of China(2042022dx0001 and 2042023kfyq01)。
文摘Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including atmospheric, hydrological, and nontidal ocean loading. Continuous improvements in the accuracy of surface mass loading products, performance of Earth models, and precise data-processing technologies have significantly advanced research on the effects of environmental loading on nonlinear variations in GNSS coordinate time series. However, owing to theoretical limitations, the lack of high spatiotemporal resolution surface mass observations, and the coupling of GNSS technology-related systematic errors, environmental loading and nonlinear GNSS reference station displacements remain inconsistent. The applicability and capability of these loading products across different regions also require further evaluation. This paper outlines methods for modeling environmental loading, surface mass loading products, and service organizations. In addition, it summarizes recent advances in applying environmental loading to address nonlinear variations in global and regional GNSS coordinate time series. Moreover, the scientific questions of existing studies are summarized, and insights into future research directions are provided. The complex nonlinear motion of reference stations is a major factor limiting the accuracy of the current terrestrial reference frame. Further refining the environmental load modeling method, establishing a surface mass distribution model with high spatiotemporal resolution and reliability, exploring other environmental load factors such as ice sheet and artificial mass-change effects, and developing an optimal data-processing model and strategy for reprocessing global reference station data consistently could contribute to the development of a millimeter-level nonlinear motion model for GNSS reference stations with actual physical significance and provide theoretical support for establishing a terrestrial reference frame with 1 mm accuracy by 2050.
基金supported by the Unveiling and Leading Projects of Gansu Provincial Department of Transportation(JT-JJ-2023-008).
文摘Accurate prediction of electric vehicle(EV)charging loads is a foundational step in the establishment of expressway charging infrastructures.This study introduces an approach to enhance the precision of expressway EV charging load predictions.The method considers both the battery dynamic state-of-charge(SOC)and user charging decisions.Expressway network nodes were first extracted using the open Gaode Map API to establish a model that incorporates the expressway network and traffic flow fea-tures.A Gaussian mixture model is then employed to construct a SOC distribution model for mixed traffic flow.An innovative SOC dynamic translation model is then introduced to capture the dynamic characteristics of traffic flow SOC values.Based on this foun-dation,an EV charging decision model was developed which considers expressway node distinctions.EV travel characteristics are extracted from the NHTS2017 datasets to assist in constructing the model.Differentiated decision-making is achieved by utilizing improved Lognormal and Sigmoid functions.Finally,the proposed method is applied to a case study of the Lian-Huo expressway.An analysis of EV charging power converges with historical data and shows that the method accurately predicts the charging loads of EVs on expressways,thus revealing the efficacy of the proposed approach in predicting EV charging dynamics under expressway scenarios.
