The paper had studied growth situation and disease symptoms of ancient trees in Surging Waves Pavilion.There were 14 ancient trees belonging to 10 genera of 9 families,with tree age of 120-260 years.These trees had be...The paper had studied growth situation and disease symptoms of ancient trees in Surging Waves Pavilion.There were 14 ancient trees belonging to 10 genera of 9 families,with tree age of 120-260 years.These trees had been well protected generally.There were 9 ancient trees growing well,occupying 64.29%,which were Ginkgo biloba,Cupressus funebris Endl.,Podocarpus macrophyllus,Zelkova schneideriana Hand.-Mazz,Cinnamomum camphora(L.)Presl,Buxus sinica,and Wisteria sinensis(Sims)Sweet.There were 5 ancient trees needing to be protected preferentially,occupying 35.71%,including Ligustrum lucidum,Osmanthus fragrans and Pterocarya stenoptera.The disease symptoms were trunk rot and hollow structure.Based on these symptoms,the paper had proposed protective measures for Ligustrum lucidum and Osmanthus fragrans:① enclosing eroding holes on the trunk;② clearing up eroded woodiness on the surface of trunk,disinfecting and applying anti-corrosion protectants;③ filling eroded holes of the trunk.Protective measures for Pterocarya stenoptera included:① clearing up the inner part and interior walls;② disinfecting the inside and interior walls of holes;③ applying anti-corrosion protectants.展开更多
The flapping motion has a great impact on the aerodynamic performance of flapping wings. In this paper, a surging motion is added to an airfoil performing pitching-plunging combined motion to figure out how it influen...The flapping motion has a great impact on the aerodynamic performance of flapping wings. In this paper, a surging motion is added to an airfoil performing pitching-plunging combined motion to figure out how it influences the lift performance and flow pattern of flapping airfoils.Firstly, the numerical methods are validated by a NACA0012 airfoil pitching case and a NACA0012 airfoil plunging case. Then, the E377m airfoil which has typical geometric characteristics of the bird-like airfoil is selected as the calculation model to study how phase differences φ1 between surging motion and plunging motion affect the aerodynamic performance of flapping airfoils. The results show that the airfoil with surging motion has comprehensively better lift performance and thrust performance than the airfoil without surging motion when 15°< φ1< 90°. It is demonstrated that surging motion has a powerful ability to improve the aerodynamic performance of flapping airfoil by adjusting φ1. Finally, to further explore how flapping airfoil improves lift performance by considering surging motion, the flapping motions of E377m airfoil with the highest lift coefficient and lift efficiency are obtained through trajectory optimization. The surging motion is removed in the highest lift case and highest lift efficiency case respectively, and the mechanism that surging motion adjusts the aerodynamic force is analyzed in detail by comparing the vortex structure and kinematic parameters. The results of this paper help reveal the aerodynamic mechanism of bird flight and guide the design of Flapping wing Micro Air Vehicles(FMAV).展开更多
Rich people in China are mainly gathered in the major and subordinate cities(the first,second & third tier cities).However,more than70% of the rich are outside of the major cities,with only 30% working and living ...Rich people in China are mainly gathered in the major and subordinate cities(the first,second & third tier cities).However,more than70% of the rich are outside of the major cities,with only 30% working and living in such展开更多
Hurricanes are one of the most destructive natural disasters that can cause catastrophic losses to both communities and infrastructure.Assessment of hurricane risk furnishes a spatial depiction of the interplay among ...Hurricanes are one of the most destructive natural disasters that can cause catastrophic losses to both communities and infrastructure.Assessment of hurricane risk furnishes a spatial depiction of the interplay among hazard,vulnerability,exposure,and mitigation capacity,crucial for understanding and managing the risks hurricanes pose to communities.These assessments aid in gauging the efficacy of existing hurricane mitigation strategies and gauging their resilience across diverse climate change scenarios.A systematic review was conducted,encompassing 94 articles,to scrutinize the structure,data inputs,assumptions,methodologies,perils modelled,and key predictors of hurricane risk.This review identified key research gaps essential for enhancing future risk assessments.The complex interaction between hurricane perils may be disastrous and underestimated in the majority of risk assessments which focus on a single peril,commonly storm surge and flood,resulting in inadequacies in disaster resilience planning.Most risk assessments were based on hurricane frequency rather than hurricane damage,which is more insightful for policymakers.Furthermore,considering secondary indirect impacts stemming from hurricanes,including real estate market and business interruption,could enrich economic impact assessments.Hurricane mitigation measures were the most under-utilised category of predictors leveraged in only 5%of studies.The top six predictive factors for hurricane risk were land use,slope,precipitation,elevation,population density,and soil texture/drainage.Another notable research gap identified was the potential of machine learning techniques in risk assessments,offering advantages over traditional MCDM and numerical models due to their ability to capture complex nonlinear relationships and adaptability to different study regions.Existing machine learning based risk assessments leverage random forest models(42%of studies)followed by neural network models(19%of studies),with further research required to investigate diverse machine learning algorithms such as ensemble models.A further research gap is model validation,in particular assessing transferability to a new study region.Additionally,harnessing simulated data and refining projections related to demographic and built environment dynamics can bolster the sophistication of climate change scenario assessments.By addressing these research gaps,hurricane risk assessments can furnish invaluable insights for national policymakers,facilitating the development of robust hurricane mitigation strategies and the construction of hurricane-resilient communities.To the authors’knowledge,this represents the first literature review specifically dedicated to quantitative hurricane risk assessments,encompassing a comparison of Multi-criteria Decision Making(MCDM),numerical models,and machine learning models.Ultimately,advancements in hurricane risk assessments and modelling stand poised to mitigate potential losses to communities and infrastructure both in the immediate and long-term future.展开更多
Southerly moisture surges over the central South China Sea(SCS)are characterized by the strengthening of lowlevel southerlies that transport moisture northward from the Pacific or Indian Oceans to South China.These su...Southerly moisture surges over the central South China Sea(SCS)are characterized by the strengthening of lowlevel southerlies that transport moisture northward from the Pacific or Indian Oceans to South China.These surge events typically occur for days in the early-summer season(from April to June)and can lead to heavy rains in South China.This study categorizes surge events into three types of flow patterns and examines their multiscale variations and impacts on rainfall.The first type occurs mainly in April,with the southeasterlies enhanced by a deepening trough in South China and the western Pacific subtropical high established over the SCS.The second type of surge events mostly appears in June,featuring the prevailing southwesterlies of summer monsoon from the Indian Ocean during the active phases of intraseasonal oscillations.Most surge events exhibit semi-diurnal variations with morning and afternoon peaks of northward moisture fluxes.Specifically,the first type features a dominant afternoon peak,while the second type shows a dominant early-morning peak,which is induced by thermal contrast between the Indochina Peninsula and the SCS.In general,the surge events enhance moisture convergence and increase rainfall downstream in South China,but they show some regional differences.The second type strengthens moisture convergence and rainfall in coastal regions with a morning peak.In contrast,the first type enhances inland rainfall with a morning peak,while moisture divergence dominates coastal regions.The third type of surge events denotes transitional conditions between the first two types,in terms of atmospheric circulations,diurnal cycles,and rainfall patterns.These results highlight a diversity of regional moisture surges and related rainfall ranging from diurnal to sub-seasonal scales.展开更多
Timely and accurate forecasting of storm surges can effectively prevent typhoon storm surges from causing large economic losses and casualties in coastal areas.At present,numerical model forecasting consumes too many ...Timely and accurate forecasting of storm surges can effectively prevent typhoon storm surges from causing large economic losses and casualties in coastal areas.At present,numerical model forecasting consumes too many resources and takes too long to compute,while neural network forecasting lacks regional data to train regional forecasting models.In this study,we used the DUAL wind model to build typhoon wind fields,and constructed a typhoon database of 75 processes in the northern South China Sea using the coupled Advanced Circulation-Simulating Waves Nearshore(ADCIRC-SWAN)model.Then,a neural network with a Res-U-Net structure was trained using the typhoon database to forecast the typhoon processes in the validation dataset,and an excellent storm surge forecasting effect was achieved in the Pearl River Estuary region.The storm surge forecasting effect of stronger typhoons was improved by adding a branch structure and transfer learning.展开更多
Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds...Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds to laser pulse and high-voltage signal while the metal coil generates an oscillating voltage pulseenvelope signal. The generation of this oscillating signal is not related to the input bias voltage of the PCSS, the pulsecircuit components, or the electrode structure of the PCSS, rather it is related to the output characteristic of the PCSS.This physical phenomenon can be explained using the current surge model in photoconducting antenna. Preparingohmic contact electrode on the silicon carbide material forms the PCSS, which generates a large number ofphotogenerated carriers when ultra-fast laser pulses irradiate the surface of the material and Simultaneously applies abias voltage signal between the electrode. At this time inside the PCSS the electric field causes the transient current,radiating electromagnetic wave to the metal coil to generate oscillating signal.展开更多
Compressor surge is a major aerodynamic instability that constrains the performance and reliability of industrial gas turbines.To address this challenge,this paper provides a comprehensive review of recent progress in...Compressor surge is a major aerodynamic instability that constrains the performance and reliability of industrial gas turbines.To address this challenge,this paper provides a comprehensive review of recent progress in surge monitoring,modeling,and control strategies.Key difficulties in early surge detection are identified,including ambiguous precursor signals,strongly coupled system dynamics,and sensor-actuator time delays.The review categorizes existing modeling approaches into high-fidelity computational fluid dynamics(CFD),reducedorder physical models,and data-driven techniques,evaluating each in terms of accuracy,adaptability,and realtime feasibility.In terms of control strategies,both passive and active methods are analyzed,with a particular focus on closed-loop feedback,model predictive control,robust control,and intelligent data-driven approaches.The review concludes by outlining future directions that prioritize model integration,control reliability,and systemlevel coordination for enhanced compressor stability.展开更多
Surge-type glaciers are widely developed in mountainous areas around the world.Understanding the trigger mechanism of glacier surge is a prerequisite for addressing their impacts on hydrological assessments,disentangl...Surge-type glaciers are widely developed in mountainous areas around the world.Understanding the trigger mechanism of glacier surge is a prerequisite for addressing their impacts on hydrological assessments,disentangling climate-glacier linkages,and mitigating downstream hazards.Most glacier surges occur in the compound glaciers;however,attention paid to the trigger mechanisms of such surges is minimal.This study confirmed two surges in the northern and southern branches of the Aru-4 glacier,respectively,in the Western Tibetan Plateau,using multisource remote sensing data.The northern branch of the Aru-4 glacier entered the active phase in 1999 and the active phase lasted for 6 years.The southern branch of the Aru-4 glacier entered the active phase in 2007 and the active phase lasted for 9 years.The southern branch of the Aru-4 glacier experienced a long period of retreat before the northern branch surged and their tongues were in a detached state.The northern branch surge carried a large amount of ice to the frontal area,blocking the downward transport of ice from the southern branch and initiated surge.Through the analysis of two surge processes of Aru-4 glacier,we found a new surge mechanism for compound glaciers.It was revealed that surges in such glaciers are not only triggered by the reduction in basal sliding resistance caused by the internal factors.These surges initiated in the upper part of the glacier then propagated to down glacier by intense compression force.Furthermore,surges can also be triggered by external intervention of blocking by other branches.This external trigger initiates the surge in the lower part of the glacier then propagated to the upper part by longitudinal traction force.In addition,comparing with the surge triggered by the internal factors,the surge triggered by the external intervention may have a more dramatic process.展开更多
Unstable operating conditions such as surge could cause damage to both aerodynamic performance and structural integrity of a compression system.This paper addresses the critical issue of aerodynamic instability in com...Unstable operating conditions such as surge could cause damage to both aerodynamic performance and structural integrity of a compression system.This paper addresses the critical issue of aerodynamic instability in compressor design,particularly focusing on an axial-centrifugal combined compressor,a widely used yet underexplored configuration.An experimental investigation was conducted on a three-stage axial and one-stage centrifugal compressor(3A1C),using two pipe systems and employing fast-responding transducers to capture the dynamic instability process from choke condition to deep surge.Results reveal that at the design speed,3A1C enters deep surge directly,whereas at off-design speeds,it experiences rotating stall and mild surge across a wide mass flow range.Some special instability features in the combined compressor can be found in the steady state map and dynamic process.The characteristic curve of the first axial stage keeps a positive slope during the whole mass flow range at an off-design speed.The first stage could work stably on the stall characteristic curve because the centrifugal stage has stronger pressurization and plays a dominant role in global aerodynamic instability.Besides,rotating instability occurs at the first rotor tip and disappears as the back pressure increases,which is also rarely seen in a single-axial compressor.This is also related to the strong pressurization of the centrifugal stage.The findings of this paper will contribute to the understanding of aerodynamic instabilities in combined compressors.展开更多
Storm surge events(SSEs)involve multiple hazard-causing factors,such as surges,extreme rainfall,strong winds,waves,and ocean currents,which have destructive impacts on coastal regions.For a quantitative multi-hazard a...Storm surge events(SSEs)involve multiple hazard-causing factors,such as surges,extreme rainfall,strong winds,waves,and ocean currents,which have destructive impacts on coastal regions.For a quantitative multi-hazard assessment of SSEs,this study introduced the concept of the storm surge event seawater-atmosphere system(SSE-SAS)and proposed the system energy equivalence(SEE)model from a systemic energy perspective.SEE was obtained by employing a parameterization approach,and the hazard index(HI)and the concept of most significant hazard(MSH)were adopted to evaluate the severity of SSE-SAS.SEE at five stations in the Shandong Peninsula was calculated from 2005 to 2019,and probability analysis and hazard assessment were further conducted.Results show that the SEE of SSE-SAS ranges from 0.029×10^(3) to 30.418×10^(3) J/m^(2),and it exhibits an insignificant decreasing trend from 2005 to 2019.The SEE of SSE-SAS in the west of the Shandong Peninsula is greater than that in the east.Moreover,storm waves,storm surges,and storm rainfall are the major contributors to SEE,which exhibit different spatial patterns and characters in different SSE-SAS types.The HI of SSE-SAS at five stations is no more than medium hazard level,with MSH at return periods of 2-to 4-year level.This study provides a new approach for quantifying multi-hazard SSEs,which offers scientific insights for regional multi-hazard risk reduction and mitigation efforts.展开更多
Lianfa Textile(002394) was founded in 1955. After decades of hard work, it has gradually grown into a large-scale textile enterprise with operations ranging from cotton processing to garment production. Its business c...Lianfa Textile(002394) was founded in 1955. After decades of hard work, it has gradually grown into a large-scale textile enterprise with operations ranging from cotton processing to garment production. Its business covers cotton spinning, yarndyed weaving, printing and dyeing, home textiles, knitting, clothing, brands, trade, logistics and new energy, among others. The company's main products include six series: yarn, yarn-dyed fabrics, printed and dyed fabrics, home textile fabrics and clothing.展开更多
The coastal regions of Laizhou Bay are highly susceptible to cold surges.This study used ERA5 reanalysis data from 2007 to 2022 and employed a hybrid model that integrates single-particle Lagrangian trajectories to st...The coastal regions of Laizhou Bay are highly susceptible to cold surges.This study used ERA5 reanalysis data from 2007 to 2022 and employed a hybrid model that integrates single-particle Lagrangian trajectories to statistically analyze the paths and intensity characteristics of cold surges in the Laizhou Bay area.Based on this analysis,a comparative analysis of outbreak processes,formation mechanisms,and causes of three different types of cold surge pathways was conducted.Results indicate variations in the characteristics of different cold surge pathways.Cold surges along the northern pathway originate from the Kara Sea.From a circula-tion perspective,the presence of a warm ridge over the Ural Mountains leads to the formation of a blocking system and an inverted‘Ω’flow pattern over Siberia.In contrast,cold surges along the northwest pathway originate from the Barents Sea,the Kara Sea,and the plains of Eastern Europe,with a pre-outbreak circulation displaying a characteristic‘ridge-trough-ridge’pattern.Finally,cold surges along the western pathway originate from the Norwegian Sea and the nearby plains of Eastern Europe,transitioning from a blocking pattern to a‘ridge-trough-ridge’pattern before the outbreak,distinguishing them from the northern and northwest path-ways.This research provides a basis for forecasting cold surge events in Laizhou Bay and for disaster prevention and mitigation in the coastal regions.展开更多
The local time-stepping(LTS)algorithm is an adaptive method that adjusts the time step by selecting suitable intervals for different regions based on the spatial scale of each cell and water depth and flow velocity be...The local time-stepping(LTS)algorithm is an adaptive method that adjusts the time step by selecting suitable intervals for different regions based on the spatial scale of each cell and water depth and flow velocity between cells.The method can be optimized by calculating the maximum power of two of the global time step increments in the domain,allowing the optimal time step to be approached throughout the grid.To verify the acceleration and accuracy of LTS in storm surge simulations,we developed a model to simulate astronomical storm surges along the southern coast of China.This model employs the shallow water equations as governing equations,numerical discretization using the finite volume method,and fluxes calculated by the Roe solver.By comparing the simulation results of the traditional global time-stepping algorithm with those of the LTS algorithm,we find that the latter fit the measured data better.Taking the calculation results of Typhoon Sally in 1996 as an example,we show that compared with the traditional global time-stepping algorithm,the LTS algorithm reduces computation time by 2.05 h and increases computation efficiency by 2.64 times while maintaining good accuracy.展开更多
To investigate the effect of typhoon path translation on storm surge augmentation,the storm surge during Typhoon 1909 Lekima in the East China Sea is simulated using Delft 3D.The model sets up three scenarios to analy...To investigate the effect of typhoon path translation on storm surge augmentation,the storm surge during Typhoon 1909 Lekima in the East China Sea is simulated using Delft 3D.The model sets up three scenarios to analyze the path’s effect on storm surge in the Shandong Peninsula Sea by shifting the typhoon path to the east and west.Results show that the areas of maximum storm surge in each scenario are located on both sides of the typhoon path and shift along with its movement.When the typhoon path shifts eastward,the maximum storm surge intensifies at Zhifu Island station 8 hours earlier.Conversely,a westward shift in the typhoon track leads to a maximum storm surge increase at Shidao Island station 12 hours earlier.Other scenarios exhibit minimal deviation from the original route.Typhoons penetrating deep inland can induce substantial storm surges,with the most extensive surge area situated in the western part of the Shandong Peninsula.展开更多
On May 14th,following the U.S.adjustment of additional tariffs on Chinese goods,American buyers began stockpiling in earnest.Many cross-border e-commerce companies also received a surge of orders.At 7 PM,a bustling Ha...On May 14th,following the U.S.adjustment of additional tariffs on Chinese goods,American buyers began stockpiling in earnest.Many cross-border e-commerce companies also received a surge of orders.At 7 PM,a bustling Hangzhou-based cross-border e-commerce company was alive with multiple languages echoing through its live-streaming rooms as backend order numbers climbed steadily.展开更多
Urban flooding in low-lying coastal regions(LCRs)is intensifying due to climate change and sea-level rise;however,the complex interplay of hydrological,climatic,and anthropogenic drivers remains poorly understood.This...Urban flooding in low-lying coastal regions(LCRs)is intensifying due to climate change and sea-level rise;however,the complex interplay of hydrological,climatic,and anthropogenic drivers remains poorly understood.This study investigates the specific meteo-hydrological factors linking climate-induced changes and human activities to the urban flooding event in My Tho City,a vulnerable coastal city in Vietnam's Tien Giang Province,from February 9 to 12,2024.Analyzing historical meteo-hydrological data(rainfall,monsoon winds,river discharge,and water levels),we examined the contributing factors.Our findings reveal that the flooding was predominantly driven by the combination of high astronomical tidal levels and significant water surges.These surges were amplified by northeast monsoon circulation.This situation was compounded by critically low Mekong River discharge during the dry season,which enhanced the inland penetration of tidal effects.Rainfall during the period was minimal and did not contribute significantly.We utilized a filtering technique to differentiate between astronomical tides and non-tidal surges in the water level data.These results provide empirical evidence demonstrating that climate-driven sea-level influences(manifesting as high tides and surges)and anthropogenic alterations to river flow governed the urban flooding dynamics.The study underscores the urgent need for integrated adaptation solutions addressing the complex land-ocean interactions, particularly in the context ofclimate change and relative sea-level rise.展开更多
This work presents an adaptive tracking guidance method for robotic fishes. The scheme enables robots to suppress external interference and eliminate motion jitter. An adaptive integral surge line-of-sight guidance ru...This work presents an adaptive tracking guidance method for robotic fishes. The scheme enables robots to suppress external interference and eliminate motion jitter. An adaptive integral surge line-of-sight guidance rule is designed to eliminate dynamics interference and sideslip issues. Limited-time yaw and surge speed observers are reported to fit disturbance variables in the model. The approximation values can compensate for the system's control input and improve the robots' tracking accuracy.Moreover, this work develops a terminal sliding mode controller and third-order differential processor to determine the rotational torque and reduce the robots' run jitter. Then, Lyapunov's theory proves the uniform ultimate boundedness of the proposed method. Simulation and physical experiments confirm that the technology improves the tracking error convergence speed and stability of robotic fishes.展开更多
基金Supported by"Study on Protection and Monitoring Warning Standard of Ancient and Rare Trees in Suzhou Classical Gardens"which is the Scientific and Technological Development Planning Project of Science and Technology Bureau of Suzhou City in2008(SS08055)~~
文摘The paper had studied growth situation and disease symptoms of ancient trees in Surging Waves Pavilion.There were 14 ancient trees belonging to 10 genera of 9 families,with tree age of 120-260 years.These trees had been well protected generally.There were 9 ancient trees growing well,occupying 64.29%,which were Ginkgo biloba,Cupressus funebris Endl.,Podocarpus macrophyllus,Zelkova schneideriana Hand.-Mazz,Cinnamomum camphora(L.)Presl,Buxus sinica,and Wisteria sinensis(Sims)Sweet.There were 5 ancient trees needing to be protected preferentially,occupying 35.71%,including Ligustrum lucidum,Osmanthus fragrans and Pterocarya stenoptera.The disease symptoms were trunk rot and hollow structure.Based on these symptoms,the paper had proposed protective measures for Ligustrum lucidum and Osmanthus fragrans:① enclosing eroding holes on the trunk;② clearing up eroded woodiness on the surface of trunk,disinfecting and applying anti-corrosion protectants;③ filling eroded holes of the trunk.Protective measures for Pterocarya stenoptera included:① clearing up the inner part and interior walls;② disinfecting the inside and interior walls of holes;③ applying anti-corrosion protectants.
基金supported by the National Natural Science Foundation of China(No.11872314)the Key R&D Program in Shaanxi Province of China(No.2020GY-154)。
文摘The flapping motion has a great impact on the aerodynamic performance of flapping wings. In this paper, a surging motion is added to an airfoil performing pitching-plunging combined motion to figure out how it influences the lift performance and flow pattern of flapping airfoils.Firstly, the numerical methods are validated by a NACA0012 airfoil pitching case and a NACA0012 airfoil plunging case. Then, the E377m airfoil which has typical geometric characteristics of the bird-like airfoil is selected as the calculation model to study how phase differences φ1 between surging motion and plunging motion affect the aerodynamic performance of flapping airfoils. The results show that the airfoil with surging motion has comprehensively better lift performance and thrust performance than the airfoil without surging motion when 15°< φ1< 90°. It is demonstrated that surging motion has a powerful ability to improve the aerodynamic performance of flapping airfoil by adjusting φ1. Finally, to further explore how flapping airfoil improves lift performance by considering surging motion, the flapping motions of E377m airfoil with the highest lift coefficient and lift efficiency are obtained through trajectory optimization. The surging motion is removed in the highest lift case and highest lift efficiency case respectively, and the mechanism that surging motion adjusts the aerodynamic force is analyzed in detail by comparing the vortex structure and kinematic parameters. The results of this paper help reveal the aerodynamic mechanism of bird flight and guide the design of Flapping wing Micro Air Vehicles(FMAV).
文摘Rich people in China are mainly gathered in the major and subordinate cities(the first,second & third tier cities).However,more than70% of the rich are outside of the major cities,with only 30% working and living in such
基金supported by the Centre for Advanced Modelling and Geospatial Information Systems(CAMGIS),University of Technology Sydney(UTS),Australia and was supported by the Research Training Program(RTP)of the Australian Government.
文摘Hurricanes are one of the most destructive natural disasters that can cause catastrophic losses to both communities and infrastructure.Assessment of hurricane risk furnishes a spatial depiction of the interplay among hazard,vulnerability,exposure,and mitigation capacity,crucial for understanding and managing the risks hurricanes pose to communities.These assessments aid in gauging the efficacy of existing hurricane mitigation strategies and gauging their resilience across diverse climate change scenarios.A systematic review was conducted,encompassing 94 articles,to scrutinize the structure,data inputs,assumptions,methodologies,perils modelled,and key predictors of hurricane risk.This review identified key research gaps essential for enhancing future risk assessments.The complex interaction between hurricane perils may be disastrous and underestimated in the majority of risk assessments which focus on a single peril,commonly storm surge and flood,resulting in inadequacies in disaster resilience planning.Most risk assessments were based on hurricane frequency rather than hurricane damage,which is more insightful for policymakers.Furthermore,considering secondary indirect impacts stemming from hurricanes,including real estate market and business interruption,could enrich economic impact assessments.Hurricane mitigation measures were the most under-utilised category of predictors leveraged in only 5%of studies.The top six predictive factors for hurricane risk were land use,slope,precipitation,elevation,population density,and soil texture/drainage.Another notable research gap identified was the potential of machine learning techniques in risk assessments,offering advantages over traditional MCDM and numerical models due to their ability to capture complex nonlinear relationships and adaptability to different study regions.Existing machine learning based risk assessments leverage random forest models(42%of studies)followed by neural network models(19%of studies),with further research required to investigate diverse machine learning algorithms such as ensemble models.A further research gap is model validation,in particular assessing transferability to a new study region.Additionally,harnessing simulated data and refining projections related to demographic and built environment dynamics can bolster the sophistication of climate change scenario assessments.By addressing these research gaps,hurricane risk assessments can furnish invaluable insights for national policymakers,facilitating the development of robust hurricane mitigation strategies and the construction of hurricane-resilient communities.To the authors’knowledge,this represents the first literature review specifically dedicated to quantitative hurricane risk assessments,encompassing a comparison of Multi-criteria Decision Making(MCDM),numerical models,and machine learning models.Ultimately,advancements in hurricane risk assessments and modelling stand poised to mitigate potential losses to communities and infrastructure both in the immediate and long-term future.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Natural Science Foundation of China(42475003)Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2023SP209)。
文摘Southerly moisture surges over the central South China Sea(SCS)are characterized by the strengthening of lowlevel southerlies that transport moisture northward from the Pacific or Indian Oceans to South China.These surge events typically occur for days in the early-summer season(from April to June)and can lead to heavy rains in South China.This study categorizes surge events into three types of flow patterns and examines their multiscale variations and impacts on rainfall.The first type occurs mainly in April,with the southeasterlies enhanced by a deepening trough in South China and the western Pacific subtropical high established over the SCS.The second type of surge events mostly appears in June,featuring the prevailing southwesterlies of summer monsoon from the Indian Ocean during the active phases of intraseasonal oscillations.Most surge events exhibit semi-diurnal variations with morning and afternoon peaks of northward moisture fluxes.Specifically,the first type features a dominant afternoon peak,while the second type shows a dominant early-morning peak,which is induced by thermal contrast between the Indochina Peninsula and the SCS.In general,the surge events enhance moisture convergence and increase rainfall downstream in South China,but they show some regional differences.The second type strengthens moisture convergence and rainfall in coastal regions with a morning peak.In contrast,the first type enhances inland rainfall with a morning peak,while moisture divergence dominates coastal regions.The third type of surge events denotes transitional conditions between the first two types,in terms of atmospheric circulations,diurnal cycles,and rainfall patterns.These results highlight a diversity of regional moisture surges and related rainfall ranging from diurnal to sub-seasonal scales.
基金supported by the National Natural Science Foundation of China(Grant No.42076214)Natural Science Foundation of Shandong Province(Grant No.ZR2024QD057).
文摘Timely and accurate forecasting of storm surges can effectively prevent typhoon storm surges from causing large economic losses and casualties in coastal areas.At present,numerical model forecasting consumes too many resources and takes too long to compute,while neural network forecasting lacks regional data to train regional forecasting models.In this study,we used the DUAL wind model to build typhoon wind fields,and constructed a typhoon database of 75 processes in the northern South China Sea using the coupled Advanced Circulation-Simulating Waves Nearshore(ADCIRC-SWAN)model.Then,a neural network with a Res-U-Net structure was trained using the typhoon database to forecast the typhoon processes in the validation dataset,and an excellent storm surge forecasting effect was achieved in the Pearl River Estuary region.The storm surge forecasting effect of stronger typhoons was improved by adding a branch structure and transfer learning.
基金supported by Major Projects of Shanxi Province (202101030201001)。
文摘Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds to laser pulse and high-voltage signal while the metal coil generates an oscillating voltage pulseenvelope signal. The generation of this oscillating signal is not related to the input bias voltage of the PCSS, the pulsecircuit components, or the electrode structure of the PCSS, rather it is related to the output characteristic of the PCSS.This physical phenomenon can be explained using the current surge model in photoconducting antenna. Preparingohmic contact electrode on the silicon carbide material forms the PCSS, which generates a large number ofphotogenerated carriers when ultra-fast laser pulses irradiate the surface of the material and Simultaneously applies abias voltage signal between the electrode. At this time inside the PCSS the electric field causes the transient current,radiating electromagnetic wave to the metal coil to generate oscillating signal.
文摘Compressor surge is a major aerodynamic instability that constrains the performance and reliability of industrial gas turbines.To address this challenge,this paper provides a comprehensive review of recent progress in surge monitoring,modeling,and control strategies.Key difficulties in early surge detection are identified,including ambiguous precursor signals,strongly coupled system dynamics,and sensor-actuator time delays.The review categorizes existing modeling approaches into high-fidelity computational fluid dynamics(CFD),reducedorder physical models,and data-driven techniques,evaluating each in terms of accuracy,adaptability,and realtime feasibility.In terms of control strategies,both passive and active methods are analyzed,with a particular focus on closed-loop feedback,model predictive control,robust control,and intelligent data-driven approaches.The review concludes by outlining future directions that prioritize model integration,control reliability,and systemlevel coordination for enhanced compressor stability.
基金funded by the Open Research Fund of TPESER(Grant No.TPESER202502)the National Key Research and Development Program of China(Grant No.2024YFF0810700)+3 种基金the Science and Technology Program Project of Gansu Province,China(Grant No.25JRRA138)the Hydraulic Science Experimental Research and Technology Extension Project of Gansu Province,China(Grant No.25GSLK094)the Open Foundation of MOE Key Laboratory of Western China's Environmental System,Lanzhou Universitythe Fundamental Research Funds for the Central Universities(Grant No.1zujbky-2025-jdzx02)。
文摘Surge-type glaciers are widely developed in mountainous areas around the world.Understanding the trigger mechanism of glacier surge is a prerequisite for addressing their impacts on hydrological assessments,disentangling climate-glacier linkages,and mitigating downstream hazards.Most glacier surges occur in the compound glaciers;however,attention paid to the trigger mechanisms of such surges is minimal.This study confirmed two surges in the northern and southern branches of the Aru-4 glacier,respectively,in the Western Tibetan Plateau,using multisource remote sensing data.The northern branch of the Aru-4 glacier entered the active phase in 1999 and the active phase lasted for 6 years.The southern branch of the Aru-4 glacier entered the active phase in 2007 and the active phase lasted for 9 years.The southern branch of the Aru-4 glacier experienced a long period of retreat before the northern branch surged and their tongues were in a detached state.The northern branch surge carried a large amount of ice to the frontal area,blocking the downward transport of ice from the southern branch and initiated surge.Through the analysis of two surge processes of Aru-4 glacier,we found a new surge mechanism for compound glaciers.It was revealed that surges in such glaciers are not only triggered by the reduction in basal sliding resistance caused by the internal factors.These surges initiated in the upper part of the glacier then propagated to down glacier by intense compression force.Furthermore,surges can also be triggered by external intervention of blocking by other branches.This external trigger initiates the surge in the lower part of the glacier then propagated to the upper part by longitudinal traction force.In addition,comparing with the surge triggered by the internal factors,the surge triggered by the external intervention may have a more dramatic process.
基金supported by the National Science and Technology Major Project of China(Nos.2017-II-0004-0016 and J2019-I-0011-0011).
文摘Unstable operating conditions such as surge could cause damage to both aerodynamic performance and structural integrity of a compression system.This paper addresses the critical issue of aerodynamic instability in compressor design,particularly focusing on an axial-centrifugal combined compressor,a widely used yet underexplored configuration.An experimental investigation was conducted on a three-stage axial and one-stage centrifugal compressor(3A1C),using two pipe systems and employing fast-responding transducers to capture the dynamic instability process from choke condition to deep surge.Results reveal that at the design speed,3A1C enters deep surge directly,whereas at off-design speeds,it experiences rotating stall and mild surge across a wide mass flow range.Some special instability features in the combined compressor can be found in the steady state map and dynamic process.The characteristic curve of the first axial stage keeps a positive slope during the whole mass flow range at an off-design speed.The first stage could work stably on the stall characteristic curve because the centrifugal stage has stronger pressurization and plays a dominant role in global aerodynamic instability.Besides,rotating instability occurs at the first rotor tip and disappears as the back pressure increases,which is also rarely seen in a single-axial compressor.This is also related to the strong pressurization of the centrifugal stage.The findings of this paper will contribute to the understanding of aerodynamic instabilities in combined compressors.
基金supported by the Key Laboratory of Coastal Science and Integrated Management,Ministry of Natural Resources(No.2022COSIMQ002)the Shandong Provincial Social Science Planning Research Project(No.22CXSXJ15)+1 种基金the Guangxi Key Laboratory of Marine Environmental Science,Guangxi Academy of Sciences(No.GXKLHY21-04)the Hainan Province Marxism Project General Program(No.2023HNMGC03).
文摘Storm surge events(SSEs)involve multiple hazard-causing factors,such as surges,extreme rainfall,strong winds,waves,and ocean currents,which have destructive impacts on coastal regions.For a quantitative multi-hazard assessment of SSEs,this study introduced the concept of the storm surge event seawater-atmosphere system(SSE-SAS)and proposed the system energy equivalence(SEE)model from a systemic energy perspective.SEE was obtained by employing a parameterization approach,and the hazard index(HI)and the concept of most significant hazard(MSH)were adopted to evaluate the severity of SSE-SAS.SEE at five stations in the Shandong Peninsula was calculated from 2005 to 2019,and probability analysis and hazard assessment were further conducted.Results show that the SEE of SSE-SAS ranges from 0.029×10^(3) to 30.418×10^(3) J/m^(2),and it exhibits an insignificant decreasing trend from 2005 to 2019.The SEE of SSE-SAS in the west of the Shandong Peninsula is greater than that in the east.Moreover,storm waves,storm surges,and storm rainfall are the major contributors to SEE,which exhibit different spatial patterns and characters in different SSE-SAS types.The HI of SSE-SAS at five stations is no more than medium hazard level,with MSH at return periods of 2-to 4-year level.This study provides a new approach for quantifying multi-hazard SSEs,which offers scientific insights for regional multi-hazard risk reduction and mitigation efforts.
文摘Lianfa Textile(002394) was founded in 1955. After decades of hard work, it has gradually grown into a large-scale textile enterprise with operations ranging from cotton processing to garment production. Its business covers cotton spinning, yarndyed weaving, printing and dyeing, home textiles, knitting, clothing, brands, trade, logistics and new energy, among others. The company's main products include six series: yarn, yarn-dyed fabrics, printed and dyed fabrics, home textile fabrics and clothing.
基金supported by the Yantai Science and Technology Innovation Project(No.2023JCYJ097).
文摘The coastal regions of Laizhou Bay are highly susceptible to cold surges.This study used ERA5 reanalysis data from 2007 to 2022 and employed a hybrid model that integrates single-particle Lagrangian trajectories to statistically analyze the paths and intensity characteristics of cold surges in the Laizhou Bay area.Based on this analysis,a comparative analysis of outbreak processes,formation mechanisms,and causes of three different types of cold surge pathways was conducted.Results indicate variations in the characteristics of different cold surge pathways.Cold surges along the northern pathway originate from the Kara Sea.From a circula-tion perspective,the presence of a warm ridge over the Ural Mountains leads to the formation of a blocking system and an inverted‘Ω’flow pattern over Siberia.In contrast,cold surges along the northwest pathway originate from the Barents Sea,the Kara Sea,and the plains of Eastern Europe,with a pre-outbreak circulation displaying a characteristic‘ridge-trough-ridge’pattern.Finally,cold surges along the western pathway originate from the Norwegian Sea and the nearby plains of Eastern Europe,transitioning from a blocking pattern to a‘ridge-trough-ridge’pattern before the outbreak,distinguishing them from the northern and northwest path-ways.This research provides a basis for forecasting cold surge events in Laizhou Bay and for disaster prevention and mitigation in the coastal regions.
基金National Natural Science Foundation of China(No.52071306)the Natural Science Foundation of Shandong Province(No.ZR2019MEE050)the Natural Science Foundation of Zhejiang Province(No.LZ22E090003).
文摘The local time-stepping(LTS)algorithm is an adaptive method that adjusts the time step by selecting suitable intervals for different regions based on the spatial scale of each cell and water depth and flow velocity between cells.The method can be optimized by calculating the maximum power of two of the global time step increments in the domain,allowing the optimal time step to be approached throughout the grid.To verify the acceleration and accuracy of LTS in storm surge simulations,we developed a model to simulate astronomical storm surges along the southern coast of China.This model employs the shallow water equations as governing equations,numerical discretization using the finite volume method,and fluxes calculated by the Roe solver.By comparing the simulation results of the traditional global time-stepping algorithm with those of the LTS algorithm,we find that the latter fit the measured data better.Taking the calculation results of Typhoon Sally in 1996 as an example,we show that compared with the traditional global time-stepping algorithm,the LTS algorithm reduces computation time by 2.05 h and increases computation efficiency by 2.64 times while maintaining good accuracy.
基金supported by the Yantai Science,Technology and Innovation Development Programme(Nos.2023 JCYJ094,2023JCYJ097)the Major Research Grant from the Natural Science Foundation of China(NSFC)(No.42330406)。
文摘To investigate the effect of typhoon path translation on storm surge augmentation,the storm surge during Typhoon 1909 Lekima in the East China Sea is simulated using Delft 3D.The model sets up three scenarios to analyze the path’s effect on storm surge in the Shandong Peninsula Sea by shifting the typhoon path to the east and west.Results show that the areas of maximum storm surge in each scenario are located on both sides of the typhoon path and shift along with its movement.When the typhoon path shifts eastward,the maximum storm surge intensifies at Zhifu Island station 8 hours earlier.Conversely,a westward shift in the typhoon track leads to a maximum storm surge increase at Shidao Island station 12 hours earlier.Other scenarios exhibit minimal deviation from the original route.Typhoons penetrating deep inland can induce substantial storm surges,with the most extensive surge area situated in the western part of the Shandong Peninsula.
文摘On May 14th,following the U.S.adjustment of additional tariffs on Chinese goods,American buyers began stockpiling in earnest.Many cross-border e-commerce companies also received a surge of orders.At 7 PM,a bustling Hangzhou-based cross-border e-commerce company was alive with multiple languages echoing through its live-streaming rooms as backend order numbers climbed steadily.
基金supported by the Vietnam National University,Ho Chi Minh City(VNU-HCM)project entitled“Identifying and quantifying drivers causing water level fluctuations in the Vietnamese Mekong Delta”grant number[B2024-18-01].
文摘Urban flooding in low-lying coastal regions(LCRs)is intensifying due to climate change and sea-level rise;however,the complex interplay of hydrological,climatic,and anthropogenic drivers remains poorly understood.This study investigates the specific meteo-hydrological factors linking climate-induced changes and human activities to the urban flooding event in My Tho City,a vulnerable coastal city in Vietnam's Tien Giang Province,from February 9 to 12,2024.Analyzing historical meteo-hydrological data(rainfall,monsoon winds,river discharge,and water levels),we examined the contributing factors.Our findings reveal that the flooding was predominantly driven by the combination of high astronomical tidal levels and significant water surges.These surges were amplified by northeast monsoon circulation.This situation was compounded by critically low Mekong River discharge during the dry season,which enhanced the inland penetration of tidal effects.Rainfall during the period was minimal and did not contribute significantly.We utilized a filtering technique to differentiate between astronomical tides and non-tidal surges in the water level data.These results provide empirical evidence demonstrating that climate-driven sea-level influences(manifesting as high tides and surges)and anthropogenic alterations to river flow governed the urban flooding dynamics.The study underscores the urgent need for integrated adaptation solutions addressing the complex land-ocean interactions, particularly in the context ofclimate change and relative sea-level rise.
基金supported in part by the National Natural Science Foundation of China(62303117,T2325018,92367109)the Xiangjiang Scholar Program(XJ2023018)+2 种基金the Key Laboratory of System Control and Information Processing(Scip20240108)the Aeronautical Science Foundation of China(20230001144001)Fujian Provincial Natural Science Foundation(2024J01130098)
文摘This work presents an adaptive tracking guidance method for robotic fishes. The scheme enables robots to suppress external interference and eliminate motion jitter. An adaptive integral surge line-of-sight guidance rule is designed to eliminate dynamics interference and sideslip issues. Limited-time yaw and surge speed observers are reported to fit disturbance variables in the model. The approximation values can compensate for the system's control input and improve the robots' tracking accuracy.Moreover, this work develops a terminal sliding mode controller and third-order differential processor to determine the rotational torque and reduce the robots' run jitter. Then, Lyapunov's theory proves the uniform ultimate boundedness of the proposed method. Simulation and physical experiments confirm that the technology improves the tracking error convergence speed and stability of robotic fishes.
