Future Changes in Various Cold Surges over China in CMIP6 Projections

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.

Trend of Storm Surge Induced by Typical Landfall Super Typhoons During 1975–2021 in the Eastern China Sea

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.

Exploration of standard dosage for GnRH antagonist protocol and dosage adjustments after premature luteinizing hormone surge

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.

A typhoon-induced storm surge numerical model with GPU acceleration based on an unstructured spherical centroidal Voronoi tessellation grid

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.

Metaverse Upsurge Drives Virtual Human Industry to Upgrade

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.

Risk assessment of coastal flooding disaster by storm surge based on Elevation-Area method and hydrodynamic models:Taking Bohai Bay as an example

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.

A Boost to Inbound Tourism China sees surge in foreign travellers following introduction of visa-free transit measures

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.

Novel layout design of 4H-SiC merged PiN Schottky diodes leading to improved surge robustness

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.

Assessment of Storm Surge and Flood Inundation in Chittagong City of Bangladesh Based on ADCIRC and GIS

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.

Numerical Study on Aerodynamic Performance of Floating Dual-Rotor Wind Turbines in Heave and Surge Motions

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.

Assessment of typhoon storm surge disaster scale based on expansion model

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.

面向防洪“四预”的数字孪生流域水利专业模型研发与实践应用--以数字孪生飞云江流域为例

数字孪生流域是推动智慧水利建设的核心和关键,而水利专业模型是数字孪生流域建设的重要算法支撑。从实际业务支撑角度研发面向防洪“四预”的数字孪生流域水利专业模型,包括水文、水动力、水工程调度、风暴潮等模型,并以浙江省温州市的数字孪生飞云江流域为载体进行实践应用。结果显示,在应对台风“杜苏芮”“卡努”“鸿雁”过程中,各类模型运行情况良好,水文、水动力及风暴潮模型预报值与实测值拟合程度较高,误差满足规范许可要求,水工程调度模型可实现模型预期调度效果。研发的水利专业模型和应用案例可为其他流域数字孪生建设提供参考。

多分水口长距离输水工程停泵水锤防护措施

为了能够有效避免多泵且多分水口输水系统在无防护抽水断电时可能出现较为严重的负水锤带来的危害,建立了全长106.46 km的大型供水工程的数学模型进行系统过渡过程计算,选择空气阀与两阶段液控蝶阀联合防护与单向塔防护2种方案消除其负水锤,在前者远不达理想防护效果后针对后者进行优化.结合工程实际在确定了单向塔的数量、位置以及塔高后,对不同位置单向塔的底面积进行多种方案的对比选取,最终选用塔1#的底面积为28.26 m^(2),塔2#的底面积为176.63 m^(2);为了防止单向塔漏空需要分水口以及供水终端调流阀配合关闭,在确保管道最大压力不超出其承压能力的前提下,创新性地对各分水口调流阀与供水终端调流阀的关闭时间规律进行了效果比较,使输水系统能够更加经济安全地稳定运行,为此类长距离多分水口多泵供水工程的水锤防护提供了优化方向.

珠海市沿海风暴潮数值模拟试验研究

基于ELCIRC模型建立了适用于珠海市海域的风暴潮模型,以1713号台风“天鸽”路径为基础,通过改变台风入射角、台风登陆点、台风移速等方式构建登陆或者影响珠海市的台风路径,并进行风暴潮数值模拟计算,分析珠海市沿海风暴潮特征。结果表明:改变台风入射角时,珠海市沿海不同岸段的风暴潮将出现较大差异性;距离台风中心约15~100 km且位于台风右半圆的沿海地区将是风暴潮的重灾区;在珠海市的香洲区和斗门区沿岸,风暴增水总体随着台风移速变慢而呈现增大的趋势,但金湾区的情况则较为复杂,当台风移速为15~30 km/h时,在沿着台风“天鸽”的移动路径上会产生较强的风暴潮过程。

航天供配电系统舵机负载浪涌抑制策略研究

随着航天器供配电系统的快速发展,大功率机电负载的使用逐渐增多,对其负载供电品质的要求也日益严格。针对高压大功率舵机负载工作状态变化大、要求响应快、动态指标高,导致机电舵机负载在工作过程中会频繁出现换向、加减速的工作特点,对电动舵机高速制动过程中产生的反灌能量进行供配电系统影响分析,提出供配电系统反灌浪涌抑制策略,提升供配电系统供电可靠性,确保航天器飞行任务中舵机负载的全程可靠运行。

光电导天线材料对辐射太赫兹波特性的模拟分析

光电导天线是太赫兹时域光谱系统中普遍使用的宽带太赫兹辐射源,天线衬底材料对其辐射太赫兹波特性至关重要。目前广泛使用的光电导天线材料是第二代半导体材料GaAs,而第三代半导体材料具有更大的禁带宽度,对提高天线辐射太赫兹波的功率更有利。本文利用大孔径光电导天线的电流瞬冲模型,对常用光电导天线材料(SI-GaAs、LT-GaAs)和未来有望应用于光电导天线的第三代半导体材料(ZnSe、GaN、SiC)辐射太赫兹波的特性进行了仿真研究,结果表明在相同偏置电场和各自最高光通量触发下,LT-GaAs天线辐射太赫兹波的幅值最高、频谱最宽;第三代半导体材料制备的天线可以承受更高的偏置电场,在各自的最大偏置电场下辐射太赫兹波的强度远远大于GaAs天线。本工作对研制新型的第三代半导体光电导天线提供了理论指导。

1300—2019年江苏沿海风暴潮灾害时空分布特征

历史上江苏沿海曾频发2类风暴潮灾害,给当地带来了巨大损失。建立该地区长时间尺度的风暴潮灾害序列对了解过去与预测未来意义重大。以历史文献、地方志、海洋灾害公报等记载的风暴潮资料为基础,建立了风暴潮灾害识别体系,重建了1300—2019年江苏沿海风暴潮灾害序列,分析了风暴潮灾害时空变化规律,探究了其与气候异常和黄河、长江入海口变迁之间的关系。结果表明:江苏沿海地区主要受台风风暴潮灾害的影响,1300—2019年间共发生246次风暴潮灾害,平均周期为2.9年,且近100年来发生频率有增大的趋势;小波分析结果显示,风暴潮灾害年际变化存在17年、61年和115年的时间尺度周期,其中115年周期最为明显。海气相互作用影响下,厄尔尼诺活跃年江苏沿海台风风暴潮灾害偏少;气温与台风风暴潮灾害频次有一定的正相关性,但其影响机制尚不明确。盐城、南通和苏州为风暴潮灾害高发地区,常州和无锡发生频率较小。在气候变暖与江苏海岸冲淤变化的作用下,1855年后盐城和南通地区风暴潮灾害发生频率增加,连云港地区明显增加;随着海岸线的变迁与长江河口的演变,镇江、扬州、泰州与苏锡常地区受风暴潮灾害影响减少。

风对波状涌潮海塘越浪水动力特性影响的数值研究

文章基于二维不可压缩两相流数值模型,首先通过对比数值计算结果与试验数据,验证了该两相流涌潮计算模型模拟波状涌潮与海塘相互作用的可靠性;然后通过设置合理的计算工况,系统分析了风速、涌潮高度、潮前水深和斜坡坡度对波状涌潮在海塘上的越浪水动力特性的影响。计算结果表明:向岸风速会显著影响波状涌潮的海塘越浪量,风速越大,涌潮的越浪量越大,且挡浪墙所受荷载也越大;随着涌潮高度和潮前水深的增大,涌潮越浪量和挡浪墙所受涌潮荷载也随之增大;当增大海塘斜坡坡度时,涌潮越浪量和挡浪墙所受涌潮荷载均呈现先增大后减小的趋势。

三峡库区滑坡涌浪作用下桥墩波压特性研究

由于三峡库区的非开敞性,滑坡引起的涌浪衰减较慢,传播过程中可能对沿程桥墩产生巨大破坏。以涪陵长江二桥为依托,构建了比例尺为1∶70的库区河道水槽,试验模拟了滑坡涌浪对桥墩的作用。结果表明:桥墩上涌浪波压分为共振波压(P_(re))和脉动波压(P_(pu)),共振波压为涌浪冲击桥墩瞬间桥墩共振产生的高频振动波,频率为300.0~400.0 Hz;脉动波压为波浪作用过程产生的压力,频率为0.2~0.5 Hz;脉动波压在对岸桥墩上沿水深的分布近似为垂直分布,在同岸桥墩沿水深锯齿状减小,最大脉动波压分布在水面附近;共振波压沿水深分为单峰值、多峰值和无峰值3种,10万m^(3)以上大方量滑坡产生的共振波压为单峰值和多峰值分布,单峰值的峰值波压是水面波压的5.0倍,多峰值的峰值波压为水面波压的2.5倍~4.0倍,10万m^(3)以下滑坡产生的共振波压呈现无峰值分布;共振波压沿水深呈先增大后减小的“侧V”形;P_(re)/P_(pu)最大位置在距水面1/3水深位置,第二大位置在距水面1/5水深位置。该文提出了桥墩迎波面涌浪压力荷载计算模型,并针对三峡库区不同运行水位给出了相应水位条件下最大涌浪波压的计算公式。

机载雷达开关电源新型防浪涌电路设计

针对机载雷达开关电源防浪涌电路在瞬态频繁开关机情况下失效率高的问题,研究了一种新型防浪涌电路。通过将栅源驱动电路和主功率充放电回路分离,分别对两个充放电时间常数独立设计,消除相关性,实现开关电源在瞬态频繁开关机状况下的有效防冲击保护。文中对常规和新型两种防浪涌电路进行了对比分析,仿真和试验结果证明了新型防浪涌电路的有效性。该电路同时具备输入防反接功能,已广泛应用于机载雷达开关电源设计。