The world’s most powerful offshore wind turbine has begun feeding electricity into the grid off the coast of southeast China,marking a major technological leap in the country’s wind power industry.The colossal turbi...The world’s most powerful offshore wind turbine has begun feeding electricity into the grid off the coast of southeast China,marking a major technological leap in the country’s wind power industry.The colossal turbine,developed and installed by China Three Gorges Corp.(CTG),is located in the Phase II Liuao offshore wind farm,more than 30 km off the coast of Fujian in waters deeper than 40 metres.The 20-mw unit successfully completed commissioning and started operation on 5 February,CTG announced.展开更多
In this paper,electrically excited synchronous machines(EESMs)using copper(Cu)and aluminum(Al)windings are compared for the feasibility of replacing Cu windings with Al windings in electric vehicle(EV)applications sin...In this paper,electrically excited synchronous machines(EESMs)using copper(Cu)and aluminum(Al)windings are compared for the feasibility of replacing Cu windings with Al windings in electric vehicle(EV)applications since Al windings have lower mass density and cost per weight,but higher resistivity and lower thermal conductivity than Cu windings.The EESMs with four winding configurations are optimized with an electromagnetic-thermal co-optimization method.The optimized EESM with only Cu windings is considered as the baseline in this study.Results show that the EESM with stator-Cu/rotor-Al windings has the least torque reduction(12.1%)compared to the baseline among the three EESMs with Al windings and the highest torque mass density among all EESMs.Meanwhile,although the new European driving cycle efficiency of the stator-Cu/rotor-Al EESM is 1.8%lower than that of the baseline,the torque per cost is 71%higher,and the maximum rotor mechanical stress is 8%lower.Therefore,the EESMs with stator-Cu/rotor-Al windings are prospective substitutions of those with only Cu windings for EV applications considering the trade-off between performance and cost.展开更多
In the quiet town of De Aar,Sipho Dube often looks up at the towering 80-metre structures and their 42-metre blades,which seem to brush the clouds.To many,they are just a wind farm,but to Dube,they represent a lifeli...In the quiet town of De Aar,Sipho Dube often looks up at the towering 80-metre structures and their 42-metre blades,which seem to brush the clouds.To many,they are just a wind farm,but to Dube,they represent a lifeline.“I once struggled to find work after studying to become an electrician.I will always be grateful that CHN Energy Longyuan Power South Africa Branch offered me not just a job but a future,”Dube told ChinAfrica.展开更多
Wind turbine blade defect detection faces persistent challenges in separating small,low-contrast surface faults from complex backgrounds while maintaining reliability under variable illumination and viewpoints.Conven-...Wind turbine blade defect detection faces persistent challenges in separating small,low-contrast surface faults from complex backgrounds while maintaining reliability under variable illumination and viewpoints.Conven-tional image-processing pipelines struggle with scalability and robustness,and recent deep learning methods remain sensitive to class imbalance and acquisition variability.This paper introduces TurbineBladeDetNet,a convolutional architecture combining dual-attention mechanisms with multi-path feature extraction for detecting five distinct blade fault types.Our approach employs both channel-wise and spatial attention modules alongside an Albumentations-driven augmentation strategy to handle dataset imbalance and capture condition variability.The model achieves 97.14%accuracy,98.65%precision,and 98.68%recall,yielding a 98.66%F1-score with 0.0110 s inference time.Class-specific analysis shows uniformly high sensitivity and specificity;lightning damage reaches 99.80%for sensitivity,precision,and F1-score,and crack achieves perfect precision and specificity with a 98.94%F1-score.Comparative evaluation against recent wind-turbine inspection approaches indicates higher performance in both accuracy and F1-score.The resulting balance of sensitivity and specificity limits both missed defects and false alarms,supporting reliable deployment in routine unmanned aerial vehicle(UAV)inspection.展开更多
This paper presents a frequency support strategy for the diode rectifier unit(DRU)-high-voltage direct current(HVDC)-based offshore wind power integration system,which coordinates multiple power sources without commun...This paper presents a frequency support strategy for the diode rectifier unit(DRU)-high-voltage direct current(HVDC)-based offshore wind power integration system,which coordinates multiple power sources without communication to reduce receiving grid frequency fluctuations.First,based on the deduced DRU's frequency transfer characteristic,a fine-designed ripple carrying frequency information is superimposed on the HVDC link,transferring the onshore frequency to offshore wind turbines(WTs)via the DC ripple and coupled AC harmonic without communication.Second,multiple power sources are utilized for frequency support,including HVDC capacitance and grid-forming WTs combined with energy storage systems,and appropriate sources are activated in the order specified by the designed thresholds.Finally,the effectiveness of the proposed frequency support strategy is verified by simulations in PSCAD/EMTDC.展开更多
Lattice-type ultra-tall wind turbine towers are popular in China for their modular benefits in fabrication,transportation,and installation.Nonetheless,their conceptual design remains predominantly dependent on enginee...Lattice-type ultra-tall wind turbine towers are popular in China for their modular benefits in fabrication,transportation,and installation.Nonetheless,their conceptual design remains predominantly dependent on engineering experience,and a generally applicable approach is still absent.This study proposes a self-similar modular topology optimization framework for lattice-type wind turbine support structures and develops software for its application.A minimum weighted compliance formulation with a prescribed volume fraction is developed utilizing the variable density approach,wherein modular constraints and their corresponding sensitivity expressions are explicitly included.The method is applied to a reference wind turbine model to generate modular lattice configurations.The novel structural models are evaluated under three representative design load cases outlined in IEC 61400 by finite element analysis.Compared with the reference structure,the 12-layer self-similar modular design reduces the maximum deformation and von Mises stress by 39.5%and 51.1%,respectively,demonstrating a substantial stiffness improvement while preserving modularity.The suggested approach provides an efficient and practical tool for the conceptual design of modular lattice-type wind turbine towers.展开更多
Inertial response control(IRC)makes variable-speed wind turbine generators(WTGs)provide short-term frequency support during contingencies by releasing the kinetic energy stored in wind turbine rotors.When frequency su...Inertial response control(IRC)makes variable-speed wind turbine generators(WTGs)provide short-term frequency support during contingencies by releasing the kinetic energy stored in wind turbine rotors.When frequency support is terminated,the rotor speed should be restored to optimum for maximum power point tracking(MPPT).Existing IRCs utilize rotor speed recovery(RSR)strategies with a consistent power reference function.However,under real turbulent wind with alternate gusts and lulls,the consistent power reference function may fail to restore rotor speed or cause unexpected secondary frequency drop(SFD).In this regard,this paper proposes a novel adaptive RSR strategy that not only restores rotor speed via the aerodynamic power enhanced by wind gusts,but also stabilizes the turbine at wind lulls by tracking a suboptimal power curve.Experiments on a wind power-integrated power system testbed validate the proposed RSR strategy can successfully restore rotor speed while attenuating SFD under turbulent wind.展开更多
2021年7月发射的风云三号E星(FY-3E)是世界首颗民用晨昏轨道气象卫星,其搭载的WindRAD双频测风雷达具有全球海面风场探测能力。本文首先基于FY-3E/WindRAD L1级观测资料,研究了雷达海面后向散射和风场之间的非线性关系,分别建立了适用于...2021年7月发射的风云三号E星(FY-3E)是世界首颗民用晨昏轨道气象卫星,其搭载的WindRAD双频测风雷达具有全球海面风场探测能力。本文首先基于FY-3E/WindRAD L1级观测资料,研究了雷达海面后向散射和风场之间的非线性关系,分别建立了适用于C和Ku波段VV/HH极化的地球物理模式函数(GMF)。随后,结合最大似然估计法(MLE)对WindRAD散射计探测资料进行风场反演。利用海洋浮标、中法海洋卫星散射计(CSCAT)和美国国家环境预报中心(NCEP)模式风场资料对WindRAD反演风场进行验证。结果显示:WindRAD反演风速与浮标风速偏差约为0.2 m s^(-1),均方根误差(RMSE)在1.13~1.44 m s^(-1)之间,优于2 m s^(-1)的业务化应用的风速精度要求;两者风向偏差在1.4°~3.0°之间,RMSE在25.3°~30.1°之间。WindRAD和CSCAT风场具有较好的一致性,风速RMSE在1.37~1.6 m s^(-1)之间,风向RMSE在22.9°~25.9°之间。WindRAD和NCEP模式风速RMSE在1.87~2.23 m s^(-1)之间,风向RMSE在22.4°~27.1°之间。研究表明WindRAD散射计C和Ku波段VV/HH极化反演风场均具有较高的精度,充分显示了WindRAD载荷在全球海面风场探测方面的应用潜力和价值。展开更多
Shenzhen,a major city in southern China,has experienced rapid advancements in Unmanned Aerial Vehicle(UAV)technology,resulting in extensive logistics networks with thousands of daily flights.However,frequent disruptio...Shenzhen,a major city in southern China,has experienced rapid advancements in Unmanned Aerial Vehicle(UAV)technology,resulting in extensive logistics networks with thousands of daily flights.However,frequent disruptions due to its subtropical monsoon climate,including typhoons and gusty winds,present ongoing challenges.Despite the growing focus on operational costs and third-party risks,research on low-altitude urban wind fields remains scarce.This study addresses this gap by integrating wind field analysis into UAV path planning,introducing key innovations to the classical model.First,UAV wind resistance and turbulence constraints are analyzed,mapping high-wind-speed and turbulence-prone zones in the airspace.Second,wind dynamics are incorporated into path planning by considering airspeed and groundspeed variation,optimizing waypoint selection and flight speed adjustments to improve overall energy efficiency.Additionally,a wind-aware Theta*algorithm is proposed,leveraging wind vectors to expedite search process,while Computational Fluid Dynamics(CFD)techniques are employed to calculate wind fields.A case study of Shenzhen,examining wind patterns over the past decade,demonstrates a 6.23%improvement in groundspeed and a 7.69%reduction in energy consumption compared to wind-agnostic models.This framework advances UAV logistics by enhancing route safety and energy efficiency,contributing to more cost-effective operations.展开更多
【Purposes】The new energy generation represented by wind power is the most realistic strategic choice to achieve the goals of carbon peaking and carbon neutrality. To absorb renewable energy electricity in power grid...【Purposes】The new energy generation represented by wind power is the most realistic strategic choice to achieve the goals of carbon peaking and carbon neutrality. To absorb renewable energy electricity in power grids, a new probabilistic evaluation method for available transmission capacity in transmission systems is proposed based on joint cumulants, and a decision model for risk available transmission capacity based on expected quantiles is proposed accordingly. As a vital component of available transmission capacity(ATC) calculation, the transmission reliability margin(TRM), as a reserved transmission capacity, reflects the impact of uncertainty factors on transmission capacity. However, in traditional calculation methods, TRM is determined through deterministic or probabilistic methods, which is difficult to reflect the risks brought by large-scale wind power consumption to ATC and cannot meet the requirements for transmission capacity risk management. 【Methods】Firstly, to address the issue that the cumulative method requires variables to be independent of each other and cannot consider the correlation of wind power output, a joint cumulative method combined with FGM Copula function is proposed to characterize the correlation of wind power output;Secondly, for the probabilistic assessment of available transmission capacity, a probabilistic assessment model for available transmission capacity is established by combining the partition integration method and the Comish Fisher expansion;Finally, in response to the problem that decision methods based on value at risk only consider the probability achieved at the tail of the probability distribution and cannot describe the risks generated throughout the distribution, a risk available transmission capacity index based on expected quantiles is proposed, and its evaluation process is proposed. 【Results】Verify the feasibility and practicality of the proposed indicators and models through case analysis.展开更多
The global energy landscape is undergoing a profound transformation,with wind energy,especially wind power,gaining increasing prominence due to its clean,renewable nature.However,as the installed capacity of wind powe...The global energy landscape is undergoing a profound transformation,with wind energy,especially wind power,gaining increasing prominence due to its clean,renewable nature.However,as the installed capacity of wind power continues to expand,the disposal of waste wind turbine blades(WWTB)has emerged as a significant challenge.These blades are predominantly composed of epoxy resin(EP)polymers,carbon fibers(CFs),and glass fibers(GFs).Improper disposal not only exacerbates environmental concerns but also leads to the loss of valuable resources,particularly carbon-based materials.Pyrolysis technology,a versatile and environmentally sustainable method for resource recovery,has garnered considerable attention in the context of WWTB disposal.This work presents a comprehensive review of the pyrolytic recycling of WWTB,focusing on the principles and classifications of pyrolysis technology,key factors influencing the pyrolysis process,as well as the pyrolysis methods,equipment,products,and their applications.Through an in-depth analysis of the current research on the pyrolytic recycling of WWTB,this review identifies critical unresolved issues in the field and provides a forward-looking perspective on emerging research trends.展开更多
Paying an additional RMB 2 could have your next milk tea delivered by drone to your balcony in just five minutes.This small fee represents the vast potential of the trillion-yuan lowaltitude economy.
Improving the electric output and durability of triboelectric nanogenerator(TENG)remains a great challenge.In sliding-mode TENG,surface charge dissipation and charge leakage caused by the volume effect result in serio...Improving the electric output and durability of triboelectric nanogenerator(TENG)remains a great challenge.In sliding-mode TENG,surface charge dissipation and charge leakage caused by the volume effect result in serious energy waste.In this work,a durable dual output mode TENG(DDO-TENG),which includes alteranting current and direct current output modes,is designed to capture the dissipating charges in the surface of charge space accumulation area and the inner leakage charge in porous network to further improve the output performance of sliding TENGs.The output charge density of DDO-TENG reaches 0.847 mC m^(-2),which is 2.39 times as that of the single mode device.In addition,it has strong durability,remaining 95.7%after over 271 k cycles,and it can continuously power electronics by harvesting wind energy.This work provides a strategy for achieving the improvement on output performance and durability and expands the application of TENG.展开更多
In wind tunnel experiments,support devices inevitably disturb the surrounding flow field,thereby degrading the accuracy of measured aerodynamic data.A new subsonic and transonic wind tunnel has recently been construct...In wind tunnel experiments,support devices inevitably disturb the surrounding flow field,thereby degrading the accuracy of measured aerodynamic data.A new subsonic and transonic wind tunnel has recently been constructed,and the support system for dynamic six degree of freedom experiments is currently under conceptual design.A key challenge is to optimize the support configuration while satisfying stringent flow quality requirements.In this study,the influence of different support configurations on the flow field is investigated numerically by analyzing velocity and pressure distributions.The results show that the optimized six degree of freedom support significantly reduces disturbances in both pressure and velocity fields,with the improvement becoming more pronounced as the Mach number increases.The main optimization measures include the addition of a tail fairing,reduction of the thickness of the connecting bases between the support rods and the sting,and downsizing of the anchor feet.In contrast,the effect of the tail support poles is found to be negligible.It is shown that,overall,the extent of upstream flow disturbance is governed primarily by the separation region and associated momentum loss induced by the support sting,the connecting bases and the anchor feet.Flow separation originates from spiral points or separation lines on the model surface,resulting from viscous effects combined with shock waves generated by the support system.展开更多
Cyperus esculentus(C.esculentus),a desert-adapted plant species with both ecological and economic value,has been widely cultivated in northern China's sandy regions.However,limited studies have investigated the pe...Cyperus esculentus(C.esculentus),a desert-adapted plant species with both ecological and economic value,has been widely cultivated in northern China's sandy regions.However,limited studies have investigated the performance of composite shelterbelts that integrate C.esculentus.This study systematically evaluated five shelterbelt models—Populus euphratica(P.euphratica),P.euphratica–C.esculentus composite,P.euphratica–nylon net–C.esculentus composite,Tamarix chinensis(T.chinensis),and T.chinensis–C.esculentus composite—using wind tunnel experiments and field observations.Sediment flux was measured at a normalized downwind distance(x/h)of 5,where x refers to the distance from the front edge(upwind side)of the shelterbelt for upwind measurements,and the distance from the rear edge(downwind side)for downwind measurements,and h represents the canopy height.Wind velocity was measured at x/h of–2,–1,1,2,3,5,and 7,and sand flux was measured at x/h=5,under initial wind velocities of 8.0 and 12.0 m/s.The results indicated that the P.euphratica–nylon net–C.esculentus composite was the most effective in reducing wind velocity,followed by the P.euphratica–C.esculentus composite.In contrast,the P.euphratica and T.chinensis exhibited relatively weaker wind reduction capabilities.Regarding sand flux,under moderate wind velocity(8.0 m/s),both the P.euphratica–C.esculentus composite and P.euphratica–nylon net–C.esculentus composite demonstrated the lowest sand flux values.However,under high wind velocity(12.0 m/s),the P.euphratica–nylon net–C.esculentus composite significantly outperformed the other shelterbelt models in sand retention,highlighting its superior windbreak and sand fixation efficacy.Field observations further validated the windbreak and sand fixation effects of C.esculentus.Comparisons between the bare sand plot and C.esculentus plot within protective forests demonstrated that planting C.esculentus can provide substantial ecological benefits in windbreak and sand-fixation.These findings,reinforced by field observations,strengthen the wind tunnel experiment results and highlight the critical role of C.esculentus in enhancing the performance of composite shelterbelts for desert ecological restoration.展开更多
Wind disturbance has emerged as a potential eco-friendly method for seedling cultivation.In this study,an electromechanical device was designed and built to investigate the effects of airflow on the micro-environment ...Wind disturbance has emerged as a potential eco-friendly method for seedling cultivation.In this study,an electromechanical device was designed and built to investigate the effects of airflow on the micro-environment and physiological activities of tomato seedlings in seedbeds by controlled experiments.The results indicated that airflow could enhance CO_(2) concentration near the seedling canopy,accelerate water evaporation from the seedling substrate,and reduce fluctuations in the temperature and humidity in microclimate.The photosynthetic rates of leaves at the 4th,7th,and 10th positions in seedlings subjected to airflow increased by 25.04%,8.23%,and 8.47%,respectively,whereas the transpiration rates increased by 15.59%,22.28%,and 13.26%,respectively when compared to the control group.Additionally,the strong seedling index of seedlings treated with airflow and exogenous iron element increased by 26.02%and 31.5%,respectively.Compared to seedlings treated with exogenous iron element,the geometric mean diameter of the pith tissue cells in the stems of seedlings subjected to airflow disturbance was reduced by approximately 18.66%,while the elastic modulus and bending strength of the stems increased by 10.01%and 5.89%,respectively.Similarly,the volume of root tissue cells decreased by 19.22%,but the elastic modulus of the roots increased by 6.46%.This study confirms that airflow significantly enhances seedling resilience to abiotic stress,yielding similar or better outcomes than exogenous iron application.It provides both theoretical and practical support for using airflow disturbance as a green technology for cultivating robust seedlings.展开更多
Ice crystal icing is an important cause of accidents in aircraft engines.Ice formation in aircraft engines can cause internal blades to freeze,affecting the quality of the air flow field and blocking the flow path.On ...Ice crystal icing is an important cause of accidents in aircraft engines.Ice formation in aircraft engines can cause internal blades to freeze,affecting the quality of the air flow field and blocking the flow path.On the other hand,the entry of ice crystal particles into the combustion chamber can cause a decrease in temperature or even flameout,leading to engine surge or shutdown.Therefore,it is necessary to conduct multiphase flow tests on ice crystals for aircraft components such as aircraft engines.Conducting ice crystal multiphase flow tests on aircraft is an effective research method,but it requires the construction of an ice crystal multiphase flow test platform that meets relevant technical requirements.The paper focuses on the relevant experimental requirements and combines wind tunnel test structures to conduct multiphase flow numerical simulations on various forms of jet pipelines,obtaining particle motion distribution results.After comparison,the optimal form of jet structure is obtained,providing the best selection scheme for the design of relevant wind tunnel structures.展开更多
In order to optimize the reaming process of the type IV composite hydrogen storage cylinder,the netting theory was employed for the design of stacking sequences,and the thickness in the head section was predicted.A fi...In order to optimize the reaming process of the type IV composite hydrogen storage cylinder,the netting theory was employed for the design of stacking sequences,and the thickness in the head section was predicted.A finite element model of the plastic-lined composite hydrogen storage cylinder,designed to withstand a working pressure of 70.0 MPa,was established by using the wound composite modeler(WCM)in the Abaqus software to analyze the forces acting on the winding layer.The Hashin failure criterion was utilized as the standard for assessing composite failure,and a progressive failure analysis of the cylinder was conducted to predict both the bursting pressure and the failure location of the composite hydrogen storage cylinder.The results indicate that the reaming process can effectively reduce the maximum filament winding thickness in the head section and promote a more uniform transition.At the bursting pressure,the stress within the head liner decreases,thereby enhancing the ultimate bearing capacity of the cylinder.A control system for a four-axis winding machine was designed by utilizing an industrial computer and a programmable multi-axis controller(PMAC).The winding line pattern is designed and the G-code trajectory is generated by the industrial computer.The numerical control system,composed of the PMAC and servo motor,executes the four-axis interpolation motion.展开更多
Predicting the precise impacts of climate change on extreme winds remains challenging,yet strong storms are widely expected to occur more frequently in a warming climate.Wind barriers are commonly used on bridges to r...Predicting the precise impacts of climate change on extreme winds remains challenging,yet strong storms are widely expected to occur more frequently in a warming climate.Wind barriers are commonly used on bridges to reduce aerodynamic loads on trains through blocking effects.This study develops a novel wind barrier based on Tesla valves,which not only blocks incoming flow but also dissipates mechanical energy through fluid collision.To demonstrate this energy-dissipation capability,a Tesla plate is placed in a circular duct to examine its influence on pressure drop.Experimental tests and numerical simulations comparing a Tesla channel and a straight channel of equal porosity show that the Tesla configuration produces a substantially higher pressure drop.Validated simulations are then used to conduct a parametric study to optimize the design.By varying the channel ratio,diversion angle,number of dissipation units,and porosity,velocity–pressure-drop relationships for different Tesla plates are obtained.The results show that larger channel ratios,larger diversion angles,and more dissipation units,combined with lower porosity,all increase pressure drop and thus enhance energy dissipation.Finally,the aerodynamic coefficients of a high-speed train on a bridge deck equipped with a Tesla-type barrier are evaluated and compared with those for a traditional straight-channel barrier.The Tesla-type barrier reduces the train’s lateral force coefficient to only 15%–25%of that produced by the traditional barrier,and it generates an additional stabilizing force that further improves running safety.展开更多
文摘The world’s most powerful offshore wind turbine has begun feeding electricity into the grid off the coast of southeast China,marking a major technological leap in the country’s wind power industry.The colossal turbine,developed and installed by China Three Gorges Corp.(CTG),is located in the Phase II Liuao offshore wind farm,more than 30 km off the coast of Fujian in waters deeper than 40 metres.The 20-mw unit successfully completed commissioning and started operation on 5 February,CTG announced.
基金supported in part by China Scholarship Council(CSC)under Grant 202206160023.
文摘In this paper,electrically excited synchronous machines(EESMs)using copper(Cu)and aluminum(Al)windings are compared for the feasibility of replacing Cu windings with Al windings in electric vehicle(EV)applications since Al windings have lower mass density and cost per weight,but higher resistivity and lower thermal conductivity than Cu windings.The EESMs with four winding configurations are optimized with an electromagnetic-thermal co-optimization method.The optimized EESM with only Cu windings is considered as the baseline in this study.Results show that the EESM with stator-Cu/rotor-Al windings has the least torque reduction(12.1%)compared to the baseline among the three EESMs with Al windings and the highest torque mass density among all EESMs.Meanwhile,although the new European driving cycle efficiency of the stator-Cu/rotor-Al EESM is 1.8%lower than that of the baseline,the torque per cost is 71%higher,and the maximum rotor mechanical stress is 8%lower.Therefore,the EESMs with stator-Cu/rotor-Al windings are prospective substitutions of those with only Cu windings for EV applications considering the trade-off between performance and cost.
文摘In the quiet town of De Aar,Sipho Dube often looks up at the towering 80-metre structures and their 42-metre blades,which seem to brush the clouds.To many,they are just a wind farm,but to Dube,they represent a lifeline.“I once struggled to find work after studying to become an electrician.I will always be grateful that CHN Energy Longyuan Power South Africa Branch offered me not just a job but a future,”Dube told ChinAfrica.
文摘Wind turbine blade defect detection faces persistent challenges in separating small,low-contrast surface faults from complex backgrounds while maintaining reliability under variable illumination and viewpoints.Conven-tional image-processing pipelines struggle with scalability and robustness,and recent deep learning methods remain sensitive to class imbalance and acquisition variability.This paper introduces TurbineBladeDetNet,a convolutional architecture combining dual-attention mechanisms with multi-path feature extraction for detecting five distinct blade fault types.Our approach employs both channel-wise and spatial attention modules alongside an Albumentations-driven augmentation strategy to handle dataset imbalance and capture condition variability.The model achieves 97.14%accuracy,98.65%precision,and 98.68%recall,yielding a 98.66%F1-score with 0.0110 s inference time.Class-specific analysis shows uniformly high sensitivity and specificity;lightning damage reaches 99.80%for sensitivity,precision,and F1-score,and crack achieves perfect precision and specificity with a 98.94%F1-score.Comparative evaluation against recent wind-turbine inspection approaches indicates higher performance in both accuracy and F1-score.The resulting balance of sensitivity and specificity limits both missed defects and false alarms,supporting reliable deployment in routine unmanned aerial vehicle(UAV)inspection.
基金supported by the State Grid Corporation of China Science and Technology Project(No.5500-202319103A-1-1-ZN).
文摘This paper presents a frequency support strategy for the diode rectifier unit(DRU)-high-voltage direct current(HVDC)-based offshore wind power integration system,which coordinates multiple power sources without communication to reduce receiving grid frequency fluctuations.First,based on the deduced DRU's frequency transfer characteristic,a fine-designed ripple carrying frequency information is superimposed on the HVDC link,transferring the onshore frequency to offshore wind turbines(WTs)via the DC ripple and coupled AC harmonic without communication.Second,multiple power sources are utilized for frequency support,including HVDC capacitance and grid-forming WTs combined with energy storage systems,and appropriate sources are activated in the order specified by the designed thresholds.Finally,the effectiveness of the proposed frequency support strategy is verified by simulations in PSCAD/EMTDC.
基金funded by the National Key Research and Development Program of China(No.2024YFE0208600)the National Natural Science Foundation of China(No.U24B2090).
文摘Lattice-type ultra-tall wind turbine towers are popular in China for their modular benefits in fabrication,transportation,and installation.Nonetheless,their conceptual design remains predominantly dependent on engineering experience,and a generally applicable approach is still absent.This study proposes a self-similar modular topology optimization framework for lattice-type wind turbine support structures and develops software for its application.A minimum weighted compliance formulation with a prescribed volume fraction is developed utilizing the variable density approach,wherein modular constraints and their corresponding sensitivity expressions are explicitly included.The method is applied to a reference wind turbine model to generate modular lattice configurations.The novel structural models are evaluated under three representative design load cases outlined in IEC 61400 by finite element analysis.Compared with the reference structure,the 12-layer self-similar modular design reduces the maximum deformation and von Mises stress by 39.5%and 51.1%,respectively,demonstrating a substantial stiffness improvement while preserving modularity.The suggested approach provides an efficient and practical tool for the conceptual design of modular lattice-type wind turbine towers.
基金supported by National Natural Science Foundation of China(51977111)the Six Talent Peaks High-level Talent Project in Jiangsu Province(XNY-025)the Special Fund of Jiangsu Province for Transformation of Scientific and Technological Achievements(BA2019045).
文摘Inertial response control(IRC)makes variable-speed wind turbine generators(WTGs)provide short-term frequency support during contingencies by releasing the kinetic energy stored in wind turbine rotors.When frequency support is terminated,the rotor speed should be restored to optimum for maximum power point tracking(MPPT).Existing IRCs utilize rotor speed recovery(RSR)strategies with a consistent power reference function.However,under real turbulent wind with alternate gusts and lulls,the consistent power reference function may fail to restore rotor speed or cause unexpected secondary frequency drop(SFD).In this regard,this paper proposes a novel adaptive RSR strategy that not only restores rotor speed via the aerodynamic power enhanced by wind gusts,but also stabilizes the turbine at wind lulls by tracking a suboptimal power curve.Experiments on a wind power-integrated power system testbed validate the proposed RSR strategy can successfully restore rotor speed while attenuating SFD under turbulent wind.
文摘2021年7月发射的风云三号E星(FY-3E)是世界首颗民用晨昏轨道气象卫星,其搭载的WindRAD双频测风雷达具有全球海面风场探测能力。本文首先基于FY-3E/WindRAD L1级观测资料,研究了雷达海面后向散射和风场之间的非线性关系,分别建立了适用于C和Ku波段VV/HH极化的地球物理模式函数(GMF)。随后,结合最大似然估计法(MLE)对WindRAD散射计探测资料进行风场反演。利用海洋浮标、中法海洋卫星散射计(CSCAT)和美国国家环境预报中心(NCEP)模式风场资料对WindRAD反演风场进行验证。结果显示:WindRAD反演风速与浮标风速偏差约为0.2 m s^(-1),均方根误差(RMSE)在1.13~1.44 m s^(-1)之间,优于2 m s^(-1)的业务化应用的风速精度要求;两者风向偏差在1.4°~3.0°之间,RMSE在25.3°~30.1°之间。WindRAD和CSCAT风场具有较好的一致性,风速RMSE在1.37~1.6 m s^(-1)之间,风向RMSE在22.9°~25.9°之间。WindRAD和NCEP模式风速RMSE在1.87~2.23 m s^(-1)之间,风向RMSE在22.4°~27.1°之间。研究表明WindRAD散射计C和Ku波段VV/HH极化反演风场均具有较高的精度,充分显示了WindRAD载荷在全球海面风场探测方面的应用潜力和价值。
基金supported by the National Natural Science Foundation of China(No.U2433214)。
文摘Shenzhen,a major city in southern China,has experienced rapid advancements in Unmanned Aerial Vehicle(UAV)technology,resulting in extensive logistics networks with thousands of daily flights.However,frequent disruptions due to its subtropical monsoon climate,including typhoons and gusty winds,present ongoing challenges.Despite the growing focus on operational costs and third-party risks,research on low-altitude urban wind fields remains scarce.This study addresses this gap by integrating wind field analysis into UAV path planning,introducing key innovations to the classical model.First,UAV wind resistance and turbulence constraints are analyzed,mapping high-wind-speed and turbulence-prone zones in the airspace.Second,wind dynamics are incorporated into path planning by considering airspeed and groundspeed variation,optimizing waypoint selection and flight speed adjustments to improve overall energy efficiency.Additionally,a wind-aware Theta*algorithm is proposed,leveraging wind vectors to expedite search process,while Computational Fluid Dynamics(CFD)techniques are employed to calculate wind fields.A case study of Shenzhen,examining wind patterns over the past decade,demonstrates a 6.23%improvement in groundspeed and a 7.69%reduction in energy consumption compared to wind-agnostic models.This framework advances UAV logistics by enhancing route safety and energy efficiency,contributing to more cost-effective operations.
文摘【Purposes】The new energy generation represented by wind power is the most realistic strategic choice to achieve the goals of carbon peaking and carbon neutrality. To absorb renewable energy electricity in power grids, a new probabilistic evaluation method for available transmission capacity in transmission systems is proposed based on joint cumulants, and a decision model for risk available transmission capacity based on expected quantiles is proposed accordingly. As a vital component of available transmission capacity(ATC) calculation, the transmission reliability margin(TRM), as a reserved transmission capacity, reflects the impact of uncertainty factors on transmission capacity. However, in traditional calculation methods, TRM is determined through deterministic or probabilistic methods, which is difficult to reflect the risks brought by large-scale wind power consumption to ATC and cannot meet the requirements for transmission capacity risk management. 【Methods】Firstly, to address the issue that the cumulative method requires variables to be independent of each other and cannot consider the correlation of wind power output, a joint cumulative method combined with FGM Copula function is proposed to characterize the correlation of wind power output;Secondly, for the probabilistic assessment of available transmission capacity, a probabilistic assessment model for available transmission capacity is established by combining the partition integration method and the Comish Fisher expansion;Finally, in response to the problem that decision methods based on value at risk only consider the probability achieved at the tail of the probability distribution and cannot describe the risks generated throughout the distribution, a risk available transmission capacity index based on expected quantiles is proposed, and its evaluation process is proposed. 【Results】Verify the feasibility and practicality of the proposed indicators and models through case analysis.
基金Supported by the National Natural Science Foundation of China(22468035,22468036,22368038,22308048)the Natural Science Foundation of Inner Mongolia(2024QN02018,2025MS02030)+2 种基金First-class Discipline Research Special Project of Inner Mongolia(YLXKZX-NGD-045)Inner Mongolia Autonomous Region Postgraduate Research Innovation Project(KC2024047B)Research Foundation for Introducing High-level Talents in Inner Mongolia Autonomous Region。
文摘The global energy landscape is undergoing a profound transformation,with wind energy,especially wind power,gaining increasing prominence due to its clean,renewable nature.However,as the installed capacity of wind power continues to expand,the disposal of waste wind turbine blades(WWTB)has emerged as a significant challenge.These blades are predominantly composed of epoxy resin(EP)polymers,carbon fibers(CFs),and glass fibers(GFs).Improper disposal not only exacerbates environmental concerns but also leads to the loss of valuable resources,particularly carbon-based materials.Pyrolysis technology,a versatile and environmentally sustainable method for resource recovery,has garnered considerable attention in the context of WWTB disposal.This work presents a comprehensive review of the pyrolytic recycling of WWTB,focusing on the principles and classifications of pyrolysis technology,key factors influencing the pyrolysis process,as well as the pyrolysis methods,equipment,products,and their applications.Through an in-depth analysis of the current research on the pyrolytic recycling of WWTB,this review identifies critical unresolved issues in the field and provides a forward-looking perspective on emerging research trends.
文摘Paying an additional RMB 2 could have your next milk tea delivered by drone to your balcony in just five minutes.This small fee represents the vast potential of the trillion-yuan lowaltitude economy.
基金supported by the Natural Science Foundation of Chongqing(Grant No.CSTB2024NSCQMSX0440)the National Key R&D Project from Minister of Science and Technology(2021YFA1201602)+2 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202400506)the Doctor Scientific Research Fund of Chongqing Normal University(Grant No.23XLB017)the Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K202200505)。
文摘Improving the electric output and durability of triboelectric nanogenerator(TENG)remains a great challenge.In sliding-mode TENG,surface charge dissipation and charge leakage caused by the volume effect result in serious energy waste.In this work,a durable dual output mode TENG(DDO-TENG),which includes alteranting current and direct current output modes,is designed to capture the dissipating charges in the surface of charge space accumulation area and the inner leakage charge in porous network to further improve the output performance of sliding TENGs.The output charge density of DDO-TENG reaches 0.847 mC m^(-2),which is 2.39 times as that of the single mode device.In addition,it has strong durability,remaining 95.7%after over 271 k cycles,and it can continuously power electronics by harvesting wind energy.This work provides a strategy for achieving the improvement on output performance and durability and expands the application of TENG.
基金supported by the Guiding Project of Scientific Research Plan of Hubei Education Department of China[Grant No.B2020227].
文摘In wind tunnel experiments,support devices inevitably disturb the surrounding flow field,thereby degrading the accuracy of measured aerodynamic data.A new subsonic and transonic wind tunnel has recently been constructed,and the support system for dynamic six degree of freedom experiments is currently under conceptual design.A key challenge is to optimize the support configuration while satisfying stringent flow quality requirements.In this study,the influence of different support configurations on the flow field is investigated numerically by analyzing velocity and pressure distributions.The results show that the optimized six degree of freedom support significantly reduces disturbances in both pressure and velocity fields,with the improvement becoming more pronounced as the Mach number increases.The main optimization measures include the addition of a tail fairing,reduction of the thickness of the connecting bases between the support rods and the sting,and downsizing of the anchor feet.In contrast,the effect of the tail support poles is found to be negligible.It is shown that,overall,the extent of upstream flow disturbance is governed primarily by the separation region and associated momentum loss induced by the support sting,the connecting bases and the anchor feet.Flow separation originates from spiral points or separation lines on the model surface,resulting from viscous effects combined with shock waves generated by the support system.
基金supported by the Xinjiang Key Research and Development Programme Project(2022B02040-2)the Tianshan Yingcai Program of Xinjiang Uygur Autonomous Region(2024TSYCLJ0028).
文摘Cyperus esculentus(C.esculentus),a desert-adapted plant species with both ecological and economic value,has been widely cultivated in northern China's sandy regions.However,limited studies have investigated the performance of composite shelterbelts that integrate C.esculentus.This study systematically evaluated five shelterbelt models—Populus euphratica(P.euphratica),P.euphratica–C.esculentus composite,P.euphratica–nylon net–C.esculentus composite,Tamarix chinensis(T.chinensis),and T.chinensis–C.esculentus composite—using wind tunnel experiments and field observations.Sediment flux was measured at a normalized downwind distance(x/h)of 5,where x refers to the distance from the front edge(upwind side)of the shelterbelt for upwind measurements,and the distance from the rear edge(downwind side)for downwind measurements,and h represents the canopy height.Wind velocity was measured at x/h of–2,–1,1,2,3,5,and 7,and sand flux was measured at x/h=5,under initial wind velocities of 8.0 and 12.0 m/s.The results indicated that the P.euphratica–nylon net–C.esculentus composite was the most effective in reducing wind velocity,followed by the P.euphratica–C.esculentus composite.In contrast,the P.euphratica and T.chinensis exhibited relatively weaker wind reduction capabilities.Regarding sand flux,under moderate wind velocity(8.0 m/s),both the P.euphratica–C.esculentus composite and P.euphratica–nylon net–C.esculentus composite demonstrated the lowest sand flux values.However,under high wind velocity(12.0 m/s),the P.euphratica–nylon net–C.esculentus composite significantly outperformed the other shelterbelt models in sand retention,highlighting its superior windbreak and sand fixation efficacy.Field observations further validated the windbreak and sand fixation effects of C.esculentus.Comparisons between the bare sand plot and C.esculentus plot within protective forests demonstrated that planting C.esculentus can provide substantial ecological benefits in windbreak and sand-fixation.These findings,reinforced by field observations,strengthen the wind tunnel experiment results and highlight the critical role of C.esculentus in enhancing the performance of composite shelterbelts for desert ecological restoration.
基金supported by an International Cooperation Key Plan of Shaanxi Province(Grant No.2022KWZ-12)an Agricultural Science Innovation and Transformation Project of Shaanxi Province[Grant No.NYKJ-2022-YL(XN)12]a High-End Foreign Expert Recruitment Program(Grant No.G2022172006L).
文摘Wind disturbance has emerged as a potential eco-friendly method for seedling cultivation.In this study,an electromechanical device was designed and built to investigate the effects of airflow on the micro-environment and physiological activities of tomato seedlings in seedbeds by controlled experiments.The results indicated that airflow could enhance CO_(2) concentration near the seedling canopy,accelerate water evaporation from the seedling substrate,and reduce fluctuations in the temperature and humidity in microclimate.The photosynthetic rates of leaves at the 4th,7th,and 10th positions in seedlings subjected to airflow increased by 25.04%,8.23%,and 8.47%,respectively,whereas the transpiration rates increased by 15.59%,22.28%,and 13.26%,respectively when compared to the control group.Additionally,the strong seedling index of seedlings treated with airflow and exogenous iron element increased by 26.02%and 31.5%,respectively.Compared to seedlings treated with exogenous iron element,the geometric mean diameter of the pith tissue cells in the stems of seedlings subjected to airflow disturbance was reduced by approximately 18.66%,while the elastic modulus and bending strength of the stems increased by 10.01%and 5.89%,respectively.Similarly,the volume of root tissue cells decreased by 19.22%,but the elastic modulus of the roots increased by 6.46%.This study confirms that airflow significantly enhances seedling resilience to abiotic stress,yielding similar or better outcomes than exogenous iron application.It provides both theoretical and practical support for using airflow disturbance as a green technology for cultivating robust seedlings.
文摘Ice crystal icing is an important cause of accidents in aircraft engines.Ice formation in aircraft engines can cause internal blades to freeze,affecting the quality of the air flow field and blocking the flow path.On the other hand,the entry of ice crystal particles into the combustion chamber can cause a decrease in temperature or even flameout,leading to engine surge or shutdown.Therefore,it is necessary to conduct multiphase flow tests on ice crystals for aircraft components such as aircraft engines.Conducting ice crystal multiphase flow tests on aircraft is an effective research method,but it requires the construction of an ice crystal multiphase flow test platform that meets relevant technical requirements.The paper focuses on the relevant experimental requirements and combines wind tunnel test structures to conduct multiphase flow numerical simulations on various forms of jet pipelines,obtaining particle motion distribution results.After comparison,the optimal form of jet structure is obtained,providing the best selection scheme for the design of relevant wind tunnel structures.
文摘In order to optimize the reaming process of the type IV composite hydrogen storage cylinder,the netting theory was employed for the design of stacking sequences,and the thickness in the head section was predicted.A finite element model of the plastic-lined composite hydrogen storage cylinder,designed to withstand a working pressure of 70.0 MPa,was established by using the wound composite modeler(WCM)in the Abaqus software to analyze the forces acting on the winding layer.The Hashin failure criterion was utilized as the standard for assessing composite failure,and a progressive failure analysis of the cylinder was conducted to predict both the bursting pressure and the failure location of the composite hydrogen storage cylinder.The results indicate that the reaming process can effectively reduce the maximum filament winding thickness in the head section and promote a more uniform transition.At the bursting pressure,the stress within the head liner decreases,thereby enhancing the ultimate bearing capacity of the cylinder.A control system for a four-axis winding machine was designed by utilizing an industrial computer and a programmable multi-axis controller(PMAC).The winding line pattern is designed and the G-code trajectory is generated by the industrial computer.The numerical control system,composed of the PMAC and servo motor,executes the four-axis interpolation motion.
基金supported by the National Natural Science Foundation of China(52475105)Special Fund for Science and Technology Innovation of Jiangsu Province(BE2022610)National Natural Science Foundation of China(U23A20661).
文摘Predicting the precise impacts of climate change on extreme winds remains challenging,yet strong storms are widely expected to occur more frequently in a warming climate.Wind barriers are commonly used on bridges to reduce aerodynamic loads on trains through blocking effects.This study develops a novel wind barrier based on Tesla valves,which not only blocks incoming flow but also dissipates mechanical energy through fluid collision.To demonstrate this energy-dissipation capability,a Tesla plate is placed in a circular duct to examine its influence on pressure drop.Experimental tests and numerical simulations comparing a Tesla channel and a straight channel of equal porosity show that the Tesla configuration produces a substantially higher pressure drop.Validated simulations are then used to conduct a parametric study to optimize the design.By varying the channel ratio,diversion angle,number of dissipation units,and porosity,velocity–pressure-drop relationships for different Tesla plates are obtained.The results show that larger channel ratios,larger diversion angles,and more dissipation units,combined with lower porosity,all increase pressure drop and thus enhance energy dissipation.Finally,the aerodynamic coefficients of a high-speed train on a bridge deck equipped with a Tesla-type barrier are evaluated and compared with those for a traditional straight-channel barrier.The Tesla-type barrier reduces the train’s lateral force coefficient to only 15%–25%of that produced by the traditional barrier,and it generates an additional stabilizing force that further improves running safety.
