In the first half year of 2007, the central government adopted a series of macro-control policies aiming at the conflicts and prob-lems existing in economic performance, resulting in a steady and fast economic growth,...In the first half year of 2007, the central government adopted a series of macro-control policies aiming at the conflicts and prob-lems existing in economic performance, resulting in a steady and fast economic growth, featured as: rapid economic growth, im-proved efficiency, harmonized structure and more substantial ben-efits to the general public.展开更多
Cold surges(CSs)often occur in the mid-latitude regions of the Northern Hemisphere and have enormous effects on socioeconomic development.We report that the occurrences of CSs and persistent CSs(PCSs)have rebounded si...Cold surges(CSs)often occur in the mid-latitude regions of the Northern Hemisphere and have enormous effects on socioeconomic development.We report that the occurrences of CSs and persistent CSs(PCSs)have rebounded since the 1990s,but the trends related to the frequencies of strong CSs(SCSs)and extreme CSs(ECSs)changed from increasing to decreasing after 2000.The highest-ranked model ensemble approach was used to project the occurrences of various CSs under the SSP1-2.6,SSP2-4.5,and SSP5-8.5 scenarios.The frequencies of the total CSs show overall decreasing trends.However,under the SSP1-2.6 scenario,slight increasing trends are noted for SCSs and ECSs in China.Atmospheric circulations that are characterized by an anomalous anticyclonic circulation with a significantly positive 500-hPa geopotential height(Z500)anomaly at high latitudes along with significant negative anomalies in China were favorable for cold air intrusions into China.In addition,the frequencies of all CS types under the SPP5-8.5 scenario greatly decreased in the long term(2071-2100),a finding which is thought to be related to negative SST anomalies in the central and western North Pacific,differences in sea level pressure(SLP)between high-and mid-latitude regions,and a weaker East Asian trough.In terms of ECSs,the decreasing trends observed during the historical period were maintained until 2024 under the SSP1-2.6 scenario.Compared to the SSP1-2.6 scenario,the Z500 pattern showed a trend of strengthened ridges over the Ural region and northern East Asia and weakened troughs over Siberia(60°-90°E)under the SSP2-4.5 and SSP5-8.5 scenarios,contributing to the shift to increasing trends of ECSs after 2014.展开更多
Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast ...Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast and thus cause casualties,economic losses,and environmental damage.Using a 3D tidal model,we reconstructed the typhoon(TY)wind field to simulate the storm surge induced by typical STYs.The TY activity was then analyzed using historical data.Results showed a downtrend of varying degrees in the annual frequency of STYs and TCs in the Western North Pacific(WNP)Basin,with a significant trend change observed for TCs from 1949 to 2021.A large difference in the interannual change in frequency was found between STYs and TCs in the WNP and Eastern China Sea(ECS).Along the coast of EC,the frequency of landfall TCs showed a weak downtrend,and the typical STYs showed reverse micro growth with peak activity in August.Zhejiang,Fujian,and Taiwan were highly vulnerable to the frontal hits of typical STYs.Affected by climate change,the average lifetime maximum intensity(LMI)locations and landfall locations of typical STYs in the ECS basin showed a significant poleward migration trend.In addition,the annual average LMI and accumulated cyclone energy showed an uptrend,indicating the increasing severity of the disaster risk.Affected by the typical STY activity in the ECS,the maximum storm surge area also showed poleward migration,and the coast of North China faced potential growth in high storm surge risks.展开更多
The future inundation by storm surge on coastal areas are currently ill-defined.With increasing global sealevel due to climate change,the coastal flooding by storm surge is more and more frequently,especially in coast...The future inundation by storm surge on coastal areas are currently ill-defined.With increasing global sealevel due to climate change,the coastal flooding by storm surge is more and more frequently,especially in coastal lowland with land subsidence.Therefore,the risk assessment of such inundation for these areas is of great significance for the sustainable socio-economic development.In this paper,the authors use Elevation-Area method and Regional Ocean Model System(ROMS)model to assess the risk of the inundation of Bohai Bay by storm surge.The simulation results of Elevation-Area method show that either a 50-year or 100-year storm surge can inundate coastal areas exceeding 8000 km^(2);the numerical simulation results based on hydrodynamics,considering ground friction and duration of the storm surge high water,show that a 50-year or 100-year storm surge can only inundate an area of over 2000 km^(2),which is far less than 8000 km^(2);while,when taking into account the land subsidence and sea level rise,the very inundation range will rapidly increase by 2050 and 2100.The storm surge will greatly impact the coastal area within about 10-30 km of the Bohai Bay,in where almost all major coastal projects are located.The prompt response to flood disaster due to storm surge is urgently needed,for which five suggestions have been proposed based on the geological background of Bohai Bay.This study may offer insight into the development of the response and adaptive plans for flooding disasters caused by storm surge.展开更多
Storm surge is often the marine disaster that poses the greatest threat to life and property in coastal areas.Accurate and timely issuance of storm surge warnings to take appropriate countermeasures is an important me...Storm surge is often the marine disaster that poses the greatest threat to life and property in coastal areas.Accurate and timely issuance of storm surge warnings to take appropriate countermeasures is an important means to reduce storm surge-related losses.Storm surge numerical models are important for storm surge forecasting.To further improve the performance of the storm surge forecast models,we developed a numerical storm surge forecast model based on an unstructured spherical centroidal Voronoi tessellation(SCVT)grid.The model is based on shallow water equations in vector-invariant form,and is discretized by Arakawa C grid.The SCVT grid can not only better describe the coastline information but also avoid rigid transitions,and it has a better global consistency by generating high-resolution grids in the key areas through transition refinement.In addition,the simulation speed of the model is accelerated by using the openACC-based GPU acceleration technology to meet the timeliness requirements of operational ensemble forecast.It only takes 37 s to simulate a day in the coastal waters of China.The newly developed storm surge model was applied to simulate typhoon-induced storm surges in the coastal waters of China.The hindcast experiments on the selected representative typhoon-induced storm surge processes indicate that the model can reasonably simulate the distribution characteristics of storm surges.The simulated maximum storm surges and their occurrence times are consistent with the observed data at the representative tide gauge stations,and the mean absolute errors are 3.5 cm and 0.6 h respectively,showing high accuracy and application prospects.展开更多
The gonadotropin-releasing hormone (GnRH) antagonist protocol has emerged as an efficacious alternative to the GnRH agonist protocol for controlled ovarian hyperstimulation (COH) during in vitro fertilization (IVF) cy...The gonadotropin-releasing hormone (GnRH) antagonist protocol has emerged as an efficacious alternative to the GnRH agonist protocol for controlled ovarian hyperstimulation (COH) during in vitro fertilization (IVF) cycles, and has been demonstrated applicability in infertile female patients with diverse ovarian responses. While the clinical implementation of the antagonist COH protocol has achieved widespread consensus, opportunities for refinement persist. Therefore, this review article focuses on the advantages and disadvantages of GnRH antagonist protocol, the selection of optimal standard doses, and the strategies for adjusting antagonist doses after the premature luteinizing hormone (LH) surge, aiming to provide more reasonable and scientific recommendations for the application of this scheme.展开更多
The concept of a virtual human is rapidly fermenting with the boom of the metaverse in 2020.In March 2021,Roblox,a game company focusing on the socialization of teenagers’games and the free realization of UGC,went pu...The concept of a virtual human is rapidly fermenting with the boom of the metaverse in 2020.In March 2021,Roblox,a game company focusing on the socialization of teenagers’games and the free realization of UGC,went public.In its prospectus,Roblox is defined as the concept of the metaverse.Under this background,as the direct embodiment of“virtual identity”and“virtual reality coexisting”under the concept of the metaverse,the emerging definition of virtual human and its representative virtual image has gradually caught the attention of the public.展开更多
Soft In Way Inc. performed the aerodynamic design of a 4 stages high pressure radial blower with vaneless diffusers and deswirlers for DMW Corporation in 2021. The nominal pressure ratio of the machine is near 2.Such ...Soft In Way Inc. performed the aerodynamic design of a 4 stages high pressure radial blower with vaneless diffusers and deswirlers for DMW Corporation in 2021. The nominal pressure ratio of the machine is near 2.Such a pressure ratio often characterizes what would typically be called a compressor, especially if the compression work is performed in one stage. For the subject machine of the present study, the compression work is split into 4 stages.This paper describes the design procedure for this blower, initially focusing in depth on the tradeoffs between work split,rotor diameter, and rotor vane back-sweep angle. The paper then presents a further design and optimization work of different variants of diffuser and deswirler based on aerodynamic performance for this 4 stages radial blower. The number of deswirler blades in the return channel was reduced from 19 to 10 in consideration of manufacturing requirements. To minimize losses in performance due to reduced blade number, several candidates of varied geometry shape deswirler blades were obtained from an automatic design and optimization workflow combining with 3D CFD calculation. All candidates of deswirler were implemented to the entire 4 stages radial blower to analyze machine performance by 3D CFD calculation and the best 10-blade deswirler geometry was determined. 3D CFD analysis shows that 10 blades of deswirler is unable to provide the same pressure rise and efficiency as the original design with 19 blades when all other parts of the design, such as rotor and diffuser are maintained the same. To further improve the blower performance, the similar automatic workflow was applied to study vaned diffuser influence to the blower performance based on the new blower configuration. The number and geometry of best diffuser blades was obtained from the automatic workflow and entire blower performance with vaned diffuser was analyzed and validated by 3D CFD calculation. After finalizing the aerodynamic flow path geometries and configuration of new blower design,performance for new blower and old one are predicted by 1D method with loss model correction and 3D CFD calculation. 1D and 3D CFD calculation results are compared and good agreement is achieved. Though, small discrepancy between them is noticed and reasons are analyzed. Furthermore, 3D CFD calculations with stall determination method based on several stall-indication metrics were performed to determine surge points of the 2 new blower configurations with vaned and vaneless diffuser. A future publication is intended to show the validation of the design with tested performance data.展开更多
One of the viral terms on Chinese social media these days-“city bu city”–was actually created by a foreign tourist.The tourist,a blogger,used the term,which literally means city or not city,in a short video he film...One of the viral terms on Chinese social media these days-“city bu city”–was actually created by a foreign tourist.The tourist,a blogger,used the term,which literally means city or not city,in a short video he filmed while visiting the Great Wall,wondering whether the place is like a fashionable big city.展开更多
According to National Bureau of Statistics of China,from January to May 2010,total profits of China’s Chemical Fibre Industry jumped 200 per cent to 8.066 billion yuan.The production rose 13.43 percent y/y to 14.4739...According to National Bureau of Statistics of China,from January to May 2010,total profits of China’s Chemical Fibre Industry jumped 200 per cent to 8.066 billion yuan.The production rose 13.43 percent y/y to 14.4739 million tons in the f irst half of 2010.Goods delivered for chemical fiber exports increased by 50.21 per cent to 792,000 from January to May from the year-earlier period.展开更多
For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention....For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention. In this study, a water hammer protection scheme combined with an overflow surge tank and a regulating valve was developed. A mathematical model of the overflow surge tank was developed, and an analytical formula for the height of the overflow surge tank was derived. Furthermore, a practical water supply project was used to evaluate the feasibility of the combined protection scheme and analyze the sensitivity of valve regulation rules. The results showed that the combined protection scheme effectively reduced the height of the surge tank, lessened the difficulties related to construction, and reduced the necessary financial investment for the project. The two-stage closing rule articulated as fast first and then slow could minimize the overflow volume of the surge tank when the power failure occurred, while the two-stage opening rule articulated as slow first and then fast could be more conducive to the safety of the water supply system when the pump started up.展开更多
A method to improve the surge current capability of silicon carbide(SiC)merged PiN Schottky(MPS)diodes is presented and investigated via three-dimensional electro-thermal simulations.When compared with a conventional ...A method to improve the surge current capability of silicon carbide(SiC)merged PiN Schottky(MPS)diodes is presented and investigated via three-dimensional electro-thermal simulations.When compared with a conventional MPS diode,the proposed structure has a more uniform current distribution during bipolar conduction due to the help of the continuous P+surface,which can avoid the formation of local hotspots during the surge process.The Silvaco simulation results show that the proposed structure has a 20.29%higher surge capability and a 15.06%higher surge energy compared with a conventional MPS diode.The bipolar on-state voltage of the proposed structure is 4.69 V,which is 56.29%lower than that of a conventional MPS diode,enabling the device to enter the bipolar mode earlier during the surge process.Furthermore,the proposed structure can suppress the occurrence of‘snapback'phenomena when switching from the unipolar to the bipolar operation mode.In addition,an analysis of the surge process of MPS diodes is carried out in detail.展开更多
Coastal flooding caused by tropical cyclones has long been a major threat to life,property,and infrastructure in coastal zones.This study assessed the risk of flooding in Chittagong,southeastern Bangladesh,under extre...Coastal flooding caused by tropical cyclones has long been a major threat to life,property,and infrastructure in coastal zones.This study assessed the risk of flooding in Chittagong,southeastern Bangladesh,under extreme sea level scenarios caused by high astronomical tides and storm surges.The Jelesnianski typhoon model and the ADvanced CIRCulation hydrodynamic model were used to simulate 91 typhoons that occurred in the Bay of Bengal between 1981 and 2017,and observational data were used for model validation.The inundation model was based on a digital elevation model and a seed spread algorithm,and a geographical information system was used to visualize the flood risk.Under four scenarios,the changes in flood levels caused by sea level rise had no signifi-cant influence on the extent of flooding in Chittagong.At flood levels of 8.82m(50-year storm surge without sea level rise)and 8.89 m(50-year storm surge with sea level rise),the maximum estimated area of inundation was 11.35 km^(2).The western coastal and southeastern river coastal plain areas of Chittagong have the highest risk of inundation due to their low-lying terrain.At flood levels of 9.83m(100-year storm surge without sea level rise)and 9.97m(100-year storm surge with sea level rise),the maximum simulated flood extent was 36.44km^(2).Simulated floodwaters propagated in a south–north direction,and most of the northern areas of the city are at risk of inundation under these scenarios.展开更多
Compared with the traditional wind turbine of a single rotor,dual-rotor wind turbines(DRWTs)have higher wind energy capture efficiency and a more complex structure.Therefore,the aerodynamic performance of the DRWT ins...Compared with the traditional wind turbine of a single rotor,dual-rotor wind turbines(DRWTs)have higher wind energy capture efficiency and a more complex structure.Therefore,the aerodynamic performance of the DRWT installed on the floating platform will be greatly affected by the motion caused by wind and wave loads.In this paper,5 MW and 750 kW single rotor wind turbines(SRWTs)are combined into a 5 MW-5 MW DRWT and a 5 MW-750 kW DRWT,and their power output and wake field characteristics in different motions are studied.The flow field is obtained by solving the Reynolds-averaged Navier–Stokes equation(RANS).The overset grid technique is employed to achieve the large-amplitude multiple-degree-of-freedom motion of the DRWT.The overall performance of the 5 MW single rotor wind turbine is determined by a numerical method.For the DRWTs,numerical results show that the surge motion and heave motion both have a negative effect on the power output of the DRWT.The surge motion is a critical factor that causes the power output of the DRWT to periodically change with motion.The average power output of the DRWT influenced by motion is lower than that of a DRWT with a fixed bottom.The surge motion significantly disturbs the wake of the DRWT due to the mutual interference between the upstream and downstream rotors.Under the influence of heave motion,low-velocity regions downstream of the blade tip are enhanced.This study indicates that attenuating the surge and heave motion of offshore DRWT is very significant for improving its efficiency and should be taken into consideration during the design procedure.展开更多
The Bohai Sea is influenced by numerous extreme oceanic wave events in history.However,it is often difficult to determine the types of these events due to the lack of detailed historical records,causing uncertainty in...The Bohai Sea is influenced by numerous extreme oceanic wave events in history.However,it is often difficult to determine the types of these events due to the lack of detailed historical records,causing uncertainty in the reconstruction of historical coastal disasters.We investigated an anomalous sand layer in the Xiliyu Village by the coast of Laizhou Bay,Shandong,from which an extreme event deposit was identified using a multi-proxy approach including grain size distribution,geochemistry,and magnetic susceptibility.This event was dated 2700–3100 a bp,and caused inundation of a large coastal area of Laizhou Bay.By comparing historical records with instrumental data,we believe that the event deposit was generated by a severe storm surge with wind speed of>34.9 m/s.展开更多
The South China Sea suffers strongly from the typhoon storm surge disasters in China,and its northern coastal areas are facing severe risks.Therefore,it is necessary and urgent to establish an assessment system for ra...The South China Sea suffers strongly from the typhoon storm surge disasters in China,and its northern coastal areas are facing severe risks.Therefore,it is necessary and urgent to establish an assessment system for rating typhoon storm surge disaster.We constructed an effective and reliable rating assessment system for typhoon storm surge disaster based on the theories of over-threshold,distribution function family,and composite extreme value.The over-threshold sample was used as the basis of data analysis,the composite extreme value expansion model was used to derive the design water increment,and then the disaster level was delineated based on the return period level.The results of the extreme value model comparison show that the Weibull-Pareto distribution is more suitable than the classical extreme value distribution for fitting the over-threshold samples.The results of the return period projection are relatively stable based on different analysis samples.Taking the 10 typhoon storm surges as examples,they caused landfall in the Guangdong area in the past 10 years.The results of the assessment ranking indicate that the risk levels based on the return period levels obtained from different distributions are generally consistent.When classifying low-risk areas,the classification criteria of the State Oceanic Administration,China(SOA,2012)are more conservative.In the high-risk areas,the results of the assessment ranking based on return period are more consistent with those of the SOA.展开更多
Lithological, petrographic, and morphoscopic studies were conducted on cuttings and cores from three boreholes drilled in the Loemé salt, Kanga site, Republic of the Congo, to determine 1) the preferential condit...Lithological, petrographic, and morphoscopic studies were conducted on cuttings and cores from three boreholes drilled in the Loemé salt, Kanga site, Republic of the Congo, to determine 1) the preferential conditions for crystallization of carnallite and associated salts and 2) to reconstruct paleoenvironmental and paleoclimatic conditions at the time of sedimentation. Sequential analysis of logs, sedimentary structures, carnallitite facies and associated salts concluded to the existence of a potassic carnallitite lagoon basin with low water cover, on a very wide and extensive plateau, affected by coastal waves and swells resulting from successive collapses. This basin evolved in two phases: confined and then open. The regular stratifications of halite, the rhythmicity of the halite-carnallitite elementary sequences are characteristic of salts that precipitated in relatively stable brines. These salts are therefore tectonosedimentary. The brecciated facies of the carnallitites sometimes associated with tachyhydrite result from the evolution of these deposits into salt crusts reworked by the surges into subaquatic allochemical gravelly cords under water. These crusts mark stages of partial and complete drying of the basin in a very hot and arid climate. Prolonged exposure of halite brines as well as their homogenization by surges accelerated evaporation and their abrupt evolution into carnallite brines obstructing the fossilization of sylvite. The precipitation of tachyhydrite marks the final stage of the successive complete drying of the basin.展开更多
The China National Climate Center and National Centers for Environmental Prediction data were used in this work. Using the knowledge of synoptic principles and synoptic analysis, the rain and snow weather process in t...The China National Climate Center and National Centers for Environmental Prediction data were used in this work. Using the knowledge of synoptic principles and synoptic analysis, the rain and snow weather process in the middle and east of China from December 28 to 30, 2020 was analyzed. The results show that: 1) This weather process was a large-scale precipitation process. Affected by the cold wave, the temperature drops sharply, and the temperature in many places dropped below the extreme value, accompanied by strong winds. 2) This process is mainly caused by the eastward movement of the upper-level trough leading the cold air southward to intersect with the warm and wet air, and the shear thread in the lower layer cooperates. 3) The cold air is from the ocean east of Novaya Zemlya. 4) From the evolution trend of 500 hPa geopotential height field and ground pressure field, the cold surge process belongs to the type of transverse trough to vertical.展开更多
In this paper, ECOMSED (Estuarine Coastal Ocean Model with sediment transport) model is employed to simulate storm surge process caused by typhoon passing across East China Sea in nearly years. Capability of ECOMSED...In this paper, ECOMSED (Estuarine Coastal Ocean Model with sediment transport) model is employed to simulate storm surge process caused by typhoon passing across East China Sea in nearly years. Capability of ECOMSED to simulate storm surge is validated by comparing model result with observed data. Sensitivity experiments are designed to study the influence of sea level rise on typhoon storm surge. Numerical experiment shows that influence of mean sea level rise on typhoon storm surge is non-uniform spatially and changes as typhoon process differs. Maybe fixed boundary method would weaken the influence of mean sea level rise on storm surge, and free boundary method is suggested for the succeeding study.展开更多
In order to facilitate engineering design and coastal flooding protection, the potential storm surge induced by a typhoon is studied.Using an unstructured mesh, a coupled model which combines the advanced circulation ...In order to facilitate engineering design and coastal flooding protection, the potential storm surge induced by a typhoon is studied.Using an unstructured mesh, a coupled model which combines the advanced circulation ( ADCIRC ) hydrodynamic model and simulating waves nearshore ( SWAN ) model is applied to analyze the storm surge and waves on the coast of Jiangsu Province.The verifications of wind velocity, tidal levels and wave height show that this coupling model performs well to reflect the characteristics of the water levels and waves in the studied region.Results show that the effect of radiation stress on storm surge is significant, especially in shallow areas such as the coast of Jiangsu Province and the Yangtze estuary.By running the coupled model, the simulated potential flooding results can be employed in coastal engineering applications in the Jiangsu coastal area, such as storm surge warnings and extreme water level predictions.展开更多
文摘In the first half year of 2007, the central government adopted a series of macro-control policies aiming at the conflicts and prob-lems existing in economic performance, resulting in a steady and fast economic growth, featured as: rapid economic growth, im-proved efficiency, harmonized structure and more substantial ben-efits to the general public.
基金supported by the National Key R&D Program of China(Grant No.2022YFF0801703)the State Key Laboratory of Earth Surface Processes and Resource Ecology(Grant No.2022-GS-01)in China.
文摘Cold surges(CSs)often occur in the mid-latitude regions of the Northern Hemisphere and have enormous effects on socioeconomic development.We report that the occurrences of CSs and persistent CSs(PCSs)have rebounded since the 1990s,but the trends related to the frequencies of strong CSs(SCSs)and extreme CSs(ECSs)changed from increasing to decreasing after 2000.The highest-ranked model ensemble approach was used to project the occurrences of various CSs under the SSP1-2.6,SSP2-4.5,and SSP5-8.5 scenarios.The frequencies of the total CSs show overall decreasing trends.However,under the SSP1-2.6 scenario,slight increasing trends are noted for SCSs and ECSs in China.Atmospheric circulations that are characterized by an anomalous anticyclonic circulation with a significantly positive 500-hPa geopotential height(Z500)anomaly at high latitudes along with significant negative anomalies in China were favorable for cold air intrusions into China.In addition,the frequencies of all CS types under the SPP5-8.5 scenario greatly decreased in the long term(2071-2100),a finding which is thought to be related to negative SST anomalies in the central and western North Pacific,differences in sea level pressure(SLP)between high-and mid-latitude regions,and a weaker East Asian trough.In terms of ECSs,the decreasing trends observed during the historical period were maintained until 2024 under the SSP1-2.6 scenario.Compared to the SSP1-2.6 scenario,the Z500 pattern showed a trend of strengthened ridges over the Ural region and northern East Asia and weakened troughs over Siberia(60°-90°E)under the SSP2-4.5 and SSP5-8.5 scenarios,contributing to the shift to increasing trends of ECSs after 2014.
基金supported by four funds,including the National Key Research and Development Program of China(No.2022YFC3106102)the Marine Science and Technology Innovation Project of Jiangsu Province(Nos.JSZRH YKJ202105,JSZRHYKI202303)+1 种基金the Nantong Social and Livelihood Science and Technology Project(Nos.MS12022009,MS22022082,MS22022083)the Project on Excellent Post-Graduate Dissertation of Hohai University(No.422003470).
文摘Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast and thus cause casualties,economic losses,and environmental damage.Using a 3D tidal model,we reconstructed the typhoon(TY)wind field to simulate the storm surge induced by typical STYs.The TY activity was then analyzed using historical data.Results showed a downtrend of varying degrees in the annual frequency of STYs and TCs in the Western North Pacific(WNP)Basin,with a significant trend change observed for TCs from 1949 to 2021.A large difference in the interannual change in frequency was found between STYs and TCs in the WNP and Eastern China Sea(ECS).Along the coast of EC,the frequency of landfall TCs showed a weak downtrend,and the typical STYs showed reverse micro growth with peak activity in August.Zhejiang,Fujian,and Taiwan were highly vulnerable to the frontal hits of typical STYs.Affected by climate change,the average lifetime maximum intensity(LMI)locations and landfall locations of typical STYs in the ECS basin showed a significant poleward migration trend.In addition,the annual average LMI and accumulated cyclone energy showed an uptrend,indicating the increasing severity of the disaster risk.Affected by the typical STY activity in the ECS,the maximum storm surge area also showed poleward migration,and the coast of North China faced potential growth in high storm surge risks.
基金supported by the National Natural Science Foundation of China(42293261)projects of the China Geological Survey(DD20230091,DD20189506,DD20211301)+1 种基金the 2024 Qinhuangdao City level Science and Technology Plan Self-Financing Project(Research on data processing methods for wave buoys in nearshore waters)the project of Hebei University of Environmental Engineering(GCZ202301)。
文摘The future inundation by storm surge on coastal areas are currently ill-defined.With increasing global sealevel due to climate change,the coastal flooding by storm surge is more and more frequently,especially in coastal lowland with land subsidence.Therefore,the risk assessment of such inundation for these areas is of great significance for the sustainable socio-economic development.In this paper,the authors use Elevation-Area method and Regional Ocean Model System(ROMS)model to assess the risk of the inundation of Bohai Bay by storm surge.The simulation results of Elevation-Area method show that either a 50-year or 100-year storm surge can inundate coastal areas exceeding 8000 km^(2);the numerical simulation results based on hydrodynamics,considering ground friction and duration of the storm surge high water,show that a 50-year or 100-year storm surge can only inundate an area of over 2000 km^(2),which is far less than 8000 km^(2);while,when taking into account the land subsidence and sea level rise,the very inundation range will rapidly increase by 2050 and 2100.The storm surge will greatly impact the coastal area within about 10-30 km of the Bohai Bay,in where almost all major coastal projects are located.The prompt response to flood disaster due to storm surge is urgently needed,for which five suggestions have been proposed based on the geological background of Bohai Bay.This study may offer insight into the development of the response and adaptive plans for flooding disasters caused by storm surge.
基金The National Natural Science Foundation of China under contract No.42076214.
文摘Storm surge is often the marine disaster that poses the greatest threat to life and property in coastal areas.Accurate and timely issuance of storm surge warnings to take appropriate countermeasures is an important means to reduce storm surge-related losses.Storm surge numerical models are important for storm surge forecasting.To further improve the performance of the storm surge forecast models,we developed a numerical storm surge forecast model based on an unstructured spherical centroidal Voronoi tessellation(SCVT)grid.The model is based on shallow water equations in vector-invariant form,and is discretized by Arakawa C grid.The SCVT grid can not only better describe the coastline information but also avoid rigid transitions,and it has a better global consistency by generating high-resolution grids in the key areas through transition refinement.In addition,the simulation speed of the model is accelerated by using the openACC-based GPU acceleration technology to meet the timeliness requirements of operational ensemble forecast.It only takes 37 s to simulate a day in the coastal waters of China.The newly developed storm surge model was applied to simulate typhoon-induced storm surges in the coastal waters of China.The hindcast experiments on the selected representative typhoon-induced storm surge processes indicate that the model can reasonably simulate the distribution characteristics of storm surges.The simulated maximum storm surges and their occurrence times are consistent with the observed data at the representative tide gauge stations,and the mean absolute errors are 3.5 cm and 0.6 h respectively,showing high accuracy and application prospects.
基金Hainan Province Major Science and Technology Plan Projects(No.ZDKJ2021037,ZDKJ2017007)National Natural Science Foundation of China(No.81960283),and Co-funded by the Hainan Provincial Academician Innovation Platform Research Project and the Hainan Provincial Clinical Medicine Center Construction Project。
文摘The gonadotropin-releasing hormone (GnRH) antagonist protocol has emerged as an efficacious alternative to the GnRH agonist protocol for controlled ovarian hyperstimulation (COH) during in vitro fertilization (IVF) cycles, and has been demonstrated applicability in infertile female patients with diverse ovarian responses. While the clinical implementation of the antagonist COH protocol has achieved widespread consensus, opportunities for refinement persist. Therefore, this review article focuses on the advantages and disadvantages of GnRH antagonist protocol, the selection of optimal standard doses, and the strategies for adjusting antagonist doses after the premature luteinizing hormone (LH) surge, aiming to provide more reasonable and scientific recommendations for the application of this scheme.
文摘The concept of a virtual human is rapidly fermenting with the boom of the metaverse in 2020.In March 2021,Roblox,a game company focusing on the socialization of teenagers’games and the free realization of UGC,went public.In its prospectus,Roblox is defined as the concept of the metaverse.Under this background,as the direct embodiment of“virtual identity”and“virtual reality coexisting”under the concept of the metaverse,the emerging definition of virtual human and its representative virtual image has gradually caught the attention of the public.
文摘Soft In Way Inc. performed the aerodynamic design of a 4 stages high pressure radial blower with vaneless diffusers and deswirlers for DMW Corporation in 2021. The nominal pressure ratio of the machine is near 2.Such a pressure ratio often characterizes what would typically be called a compressor, especially if the compression work is performed in one stage. For the subject machine of the present study, the compression work is split into 4 stages.This paper describes the design procedure for this blower, initially focusing in depth on the tradeoffs between work split,rotor diameter, and rotor vane back-sweep angle. The paper then presents a further design and optimization work of different variants of diffuser and deswirler based on aerodynamic performance for this 4 stages radial blower. The number of deswirler blades in the return channel was reduced from 19 to 10 in consideration of manufacturing requirements. To minimize losses in performance due to reduced blade number, several candidates of varied geometry shape deswirler blades were obtained from an automatic design and optimization workflow combining with 3D CFD calculation. All candidates of deswirler were implemented to the entire 4 stages radial blower to analyze machine performance by 3D CFD calculation and the best 10-blade deswirler geometry was determined. 3D CFD analysis shows that 10 blades of deswirler is unable to provide the same pressure rise and efficiency as the original design with 19 blades when all other parts of the design, such as rotor and diffuser are maintained the same. To further improve the blower performance, the similar automatic workflow was applied to study vaned diffuser influence to the blower performance based on the new blower configuration. The number and geometry of best diffuser blades was obtained from the automatic workflow and entire blower performance with vaned diffuser was analyzed and validated by 3D CFD calculation. After finalizing the aerodynamic flow path geometries and configuration of new blower design,performance for new blower and old one are predicted by 1D method with loss model correction and 3D CFD calculation. 1D and 3D CFD calculation results are compared and good agreement is achieved. Though, small discrepancy between them is noticed and reasons are analyzed. Furthermore, 3D CFD calculations with stall determination method based on several stall-indication metrics were performed to determine surge points of the 2 new blower configurations with vaned and vaneless diffuser. A future publication is intended to show the validation of the design with tested performance data.
文摘One of the viral terms on Chinese social media these days-“city bu city”–was actually created by a foreign tourist.The tourist,a blogger,used the term,which literally means city or not city,in a short video he filmed while visiting the Great Wall,wondering whether the place is like a fashionable big city.
文摘According to National Bureau of Statistics of China,from January to May 2010,total profits of China’s Chemical Fibre Industry jumped 200 per cent to 8.066 billion yuan.The production rose 13.43 percent y/y to 14.4739 million tons in the f irst half of 2010.Goods delivered for chemical fiber exports increased by 50.21 per cent to 792,000 from January to May from the year-earlier period.
基金supported by the National Natural Science Foundation of China(Grants No.52179062 and 51879087).
文摘For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention. In this study, a water hammer protection scheme combined with an overflow surge tank and a regulating valve was developed. A mathematical model of the overflow surge tank was developed, and an analytical formula for the height of the overflow surge tank was derived. Furthermore, a practical water supply project was used to evaluate the feasibility of the combined protection scheme and analyze the sensitivity of valve regulation rules. The results showed that the combined protection scheme effectively reduced the height of the surge tank, lessened the difficulties related to construction, and reduced the necessary financial investment for the project. The two-stage closing rule articulated as fast first and then slow could minimize the overflow volume of the surge tank when the power failure occurred, while the two-stage opening rule articulated as slow first and then fast could be more conducive to the safety of the water supply system when the pump started up.
基金the National Research and Development Program for Major Research Instruments of China(Grant No.62027814)the National Natural Science Foundation of China(Grant No.61904045)Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ20F040004)。
文摘A method to improve the surge current capability of silicon carbide(SiC)merged PiN Schottky(MPS)diodes is presented and investigated via three-dimensional electro-thermal simulations.When compared with a conventional MPS diode,the proposed structure has a more uniform current distribution during bipolar conduction due to the help of the continuous P+surface,which can avoid the formation of local hotspots during the surge process.The Silvaco simulation results show that the proposed structure has a 20.29%higher surge capability and a 15.06%higher surge energy compared with a conventional MPS diode.The bipolar on-state voltage of the proposed structure is 4.69 V,which is 56.29%lower than that of a conventional MPS diode,enabling the device to enter the bipolar mode earlier during the surge process.Furthermore,the proposed structure can suppress the occurrence of‘snapback'phenomena when switching from the unipolar to the bipolar operation mode.In addition,an analysis of the surge process of MPS diodes is carried out in detail.
基金funded by the National Key Research and Development Program of China(No.2016YFC1401103)Funds for the Central Universities(No.202165003)the Open Fund of Shandong Province Key Laboratory of Ocean Engineering,Ocean University of China(No.kloe201903).
文摘Coastal flooding caused by tropical cyclones has long been a major threat to life,property,and infrastructure in coastal zones.This study assessed the risk of flooding in Chittagong,southeastern Bangladesh,under extreme sea level scenarios caused by high astronomical tides and storm surges.The Jelesnianski typhoon model and the ADvanced CIRCulation hydrodynamic model were used to simulate 91 typhoons that occurred in the Bay of Bengal between 1981 and 2017,and observational data were used for model validation.The inundation model was based on a digital elevation model and a seed spread algorithm,and a geographical information system was used to visualize the flood risk.Under four scenarios,the changes in flood levels caused by sea level rise had no signifi-cant influence on the extent of flooding in Chittagong.At flood levels of 8.82m(50-year storm surge without sea level rise)and 8.89 m(50-year storm surge with sea level rise),the maximum estimated area of inundation was 11.35 km^(2).The western coastal and southeastern river coastal plain areas of Chittagong have the highest risk of inundation due to their low-lying terrain.At flood levels of 9.83m(100-year storm surge without sea level rise)and 9.97m(100-year storm surge with sea level rise),the maximum simulated flood extent was 36.44km^(2).Simulated floodwaters propagated in a south–north direction,and most of the northern areas of the city are at risk of inundation under these scenarios.
基金financially supported by the Guangdong Basic and Applied Basic Research Foundation,China (Grant Nos.2021A1515011771 and 2022B1515250005)the National Natural Science Foundation of China (Grant Nos.52171289,52201350,and 52201394)+1 种基金the National Key Research and Development Program of China (Grant No.2022YFC28063)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant No.SML 2022016)。
文摘Compared with the traditional wind turbine of a single rotor,dual-rotor wind turbines(DRWTs)have higher wind energy capture efficiency and a more complex structure.Therefore,the aerodynamic performance of the DRWT installed on the floating platform will be greatly affected by the motion caused by wind and wave loads.In this paper,5 MW and 750 kW single rotor wind turbines(SRWTs)are combined into a 5 MW-5 MW DRWT and a 5 MW-750 kW DRWT,and their power output and wake field characteristics in different motions are studied.The flow field is obtained by solving the Reynolds-averaged Navier–Stokes equation(RANS).The overset grid technique is employed to achieve the large-amplitude multiple-degree-of-freedom motion of the DRWT.The overall performance of the 5 MW single rotor wind turbine is determined by a numerical method.For the DRWTs,numerical results show that the surge motion and heave motion both have a negative effect on the power output of the DRWT.The surge motion is a critical factor that causes the power output of the DRWT to periodically change with motion.The average power output of the DRWT influenced by motion is lower than that of a DRWT with a fixed bottom.The surge motion significantly disturbs the wake of the DRWT due to the mutual interference between the upstream and downstream rotors.Under the influence of heave motion,low-velocity regions downstream of the blade tip are enhanced.This study indicates that attenuating the surge and heave motion of offshore DRWT is very significant for improving its efficiency and should be taken into consideration during the design procedure.
基金Supported by the National Natural Science Foundation of China(Nos.41706096,41530962,41771218)the Research Start-up Project of Jiangsu Normal University(No.19XSRX006)the Opening Foundation of Hainan Key Laboratory of Marine Geological Resources and Environment(No.HNHYDZZYHJKF005)。
文摘The Bohai Sea is influenced by numerous extreme oceanic wave events in history.However,it is often difficult to determine the types of these events due to the lack of detailed historical records,causing uncertainty in the reconstruction of historical coastal disasters.We investigated an anomalous sand layer in the Xiliyu Village by the coast of Laizhou Bay,Shandong,from which an extreme event deposit was identified using a multi-proxy approach including grain size distribution,geochemistry,and magnetic susceptibility.This event was dated 2700–3100 a bp,and caused inundation of a large coastal area of Laizhou Bay.By comparing historical records with instrumental data,we believe that the event deposit was generated by a severe storm surge with wind speed of>34.9 m/s.
基金Supported by the National Natural Science Foundation of China(Nos.52071306,52101360)the Natural Science Foundation of Shandong Province(No.ZR2019MEE050)the State Key Laboratory of Coastal and Offshore Engineering(No.LP2104)。
文摘The South China Sea suffers strongly from the typhoon storm surge disasters in China,and its northern coastal areas are facing severe risks.Therefore,it is necessary and urgent to establish an assessment system for rating typhoon storm surge disaster.We constructed an effective and reliable rating assessment system for typhoon storm surge disaster based on the theories of over-threshold,distribution function family,and composite extreme value.The over-threshold sample was used as the basis of data analysis,the composite extreme value expansion model was used to derive the design water increment,and then the disaster level was delineated based on the return period level.The results of the extreme value model comparison show that the Weibull-Pareto distribution is more suitable than the classical extreme value distribution for fitting the over-threshold samples.The results of the return period projection are relatively stable based on different analysis samples.Taking the 10 typhoon storm surges as examples,they caused landfall in the Guangdong area in the past 10 years.The results of the assessment ranking indicate that the risk levels based on the return period levels obtained from different distributions are generally consistent.When classifying low-risk areas,the classification criteria of the State Oceanic Administration,China(SOA,2012)are more conservative.In the high-risk areas,the results of the assessment ranking based on return period are more consistent with those of the SOA.
文摘Lithological, petrographic, and morphoscopic studies were conducted on cuttings and cores from three boreholes drilled in the Loemé salt, Kanga site, Republic of the Congo, to determine 1) the preferential conditions for crystallization of carnallite and associated salts and 2) to reconstruct paleoenvironmental and paleoclimatic conditions at the time of sedimentation. Sequential analysis of logs, sedimentary structures, carnallitite facies and associated salts concluded to the existence of a potassic carnallitite lagoon basin with low water cover, on a very wide and extensive plateau, affected by coastal waves and swells resulting from successive collapses. This basin evolved in two phases: confined and then open. The regular stratifications of halite, the rhythmicity of the halite-carnallitite elementary sequences are characteristic of salts that precipitated in relatively stable brines. These salts are therefore tectonosedimentary. The brecciated facies of the carnallitites sometimes associated with tachyhydrite result from the evolution of these deposits into salt crusts reworked by the surges into subaquatic allochemical gravelly cords under water. These crusts mark stages of partial and complete drying of the basin in a very hot and arid climate. Prolonged exposure of halite brines as well as their homogenization by surges accelerated evaporation and their abrupt evolution into carnallite brines obstructing the fossilization of sylvite. The precipitation of tachyhydrite marks the final stage of the successive complete drying of the basin.
文摘The China National Climate Center and National Centers for Environmental Prediction data were used in this work. Using the knowledge of synoptic principles and synoptic analysis, the rain and snow weather process in the middle and east of China from December 28 to 30, 2020 was analyzed. The results show that: 1) This weather process was a large-scale precipitation process. Affected by the cold wave, the temperature drops sharply, and the temperature in many places dropped below the extreme value, accompanied by strong winds. 2) This process is mainly caused by the eastward movement of the upper-level trough leading the cold air southward to intersect with the warm and wet air, and the shear thread in the lower layer cooperates. 3) The cold air is from the ocean east of Novaya Zemlya. 4) From the evolution trend of 500 hPa geopotential height field and ground pressure field, the cold surge process belongs to the type of transverse trough to vertical.
文摘In this paper, ECOMSED (Estuarine Coastal Ocean Model with sediment transport) model is employed to simulate storm surge process caused by typhoon passing across East China Sea in nearly years. Capability of ECOMSED to simulate storm surge is validated by comparing model result with observed data. Sensitivity experiments are designed to study the influence of sea level rise on typhoon storm surge. Numerical experiment shows that influence of mean sea level rise on typhoon storm surge is non-uniform spatially and changes as typhoon process differs. Maybe fixed boundary method would weaken the influence of mean sea level rise on storm surge, and free boundary method is suggested for the succeeding study.
基金The National Natural Science Foundation of China(No.51209040,51279134)the Natural Science Foundation of Jiangsu Province(No.BK2012341)+1 种基金the Fundamental Research Funds for the Central Universities(No.SJLX_0087)the Research Fund of Nanjing Hydraulic Research Institute(No.Y213012)
文摘In order to facilitate engineering design and coastal flooding protection, the potential storm surge induced by a typhoon is studied.Using an unstructured mesh, a coupled model which combines the advanced circulation ( ADCIRC ) hydrodynamic model and simulating waves nearshore ( SWAN ) model is applied to analyze the storm surge and waves on the coast of Jiangsu Province.The verifications of wind velocity, tidal levels and wave height show that this coupling model performs well to reflect the characteristics of the water levels and waves in the studied region.Results show that the effect of radiation stress on storm surge is significant, especially in shallow areas such as the coast of Jiangsu Province and the Yangtze estuary.By running the coupled model, the simulated potential flooding results can be employed in coastal engineering applications in the Jiangsu coastal area, such as storm surge warnings and extreme water level predictions.