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STABILITY OF TIME-PERIODIC TRAVELING FRONTS IN BISTABLE REACTION-ADVECTION-DIFFUSION EQUATIONS
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作者 盛伟杰 《Acta Mathematica Scientia》 SCIE CSCD 2016年第3期802-814,共13页
This paper is concerned with the global exponential stability of time periodic traveling fronts of reaction-advection-diffusion equations with time periodic bistable nonlinearity in infinite cylinders. It is well know... This paper is concerned with the global exponential stability of time periodic traveling fronts of reaction-advection-diffusion equations with time periodic bistable nonlinearity in infinite cylinders. It is well known that such traveling fronts exist and are asymptotically stable. In this paper, we further show that such fronts are globally exponentially stable. The main difficulty is to construct appropriate supersolutions and subsolutions. 展开更多
关键词 STABILITY reaction-advection-diffusion equations BISTABLE time periodic tray- eling fronts
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Characteristics of Water Environment in Regions of Zhaling and Eling Lakes near Waterhead of Yellow River
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作者 Cao Wenbing Wan Li Hu Fusheng Shen Zhaoli Department of Water Resources and Environmental Engineering, China University of Geosciences, Beijing 100083 Yan Weide Qinghai Exploring Institute of Hydrogeology and Engineering Geology, Ledu 810700 《Journal of China University of Geosciences》 SCIE CSCD 2001年第2期137-141,共5页
Conditions of the water environment in the region of the Zhaling and Eling lakes, which are located in the frozen earth zone on the Qingzang plateau, are unique. The equilibrium of the water quantity of the two lakes... Conditions of the water environment in the region of the Zhaling and Eling lakes, which are located in the frozen earth zone on the Qingzang plateau, are unique. The equilibrium of the water quantity of the two lakes is maladjustment under the condition of a dry and cold climate in which evaporation is greater than precipitation. The Zhaling and Eling lakes have been atrophying, leaving three lake terraces and star studded lagoons around the two lakes since Holocene. When these lagoons were separated from the original lakes, they became cut lake basins, and were transformed from fresh water lakes into salt water lakes, salt lakes or salt playas owing to strong evaporation. This kind of evolutionary process will continue in the future. 展开更多
关键词 water environment atrophy of lakes Zhaling and eling lakes Qingzang plateau.
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Convenient Way of Extend Linear Expenditure System Modeling without Regression 被引量:1
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作者 Ningning Song Yiqing Liu 《Open Journal of Statistics》 2015年第6期519-524,共6页
Extend Linear Expenditure System model is a collection of multiple linear models, and modeling is a clearly tedious process. The innovation of this paper is trying to find a simple way of ELES modeling, which means, i... Extend Linear Expenditure System model is a collection of multiple linear models, and modeling is a clearly tedious process. The innovation of this paper is trying to find a simple way of ELES modeling, which means, in order to omit the modeling process one by one, we try to use Excel functionality to create a model workplace. As long as you replace the original sample data in the workspace, you can get the results you want. 展开更多
关键词 ELES Model OLS WLS
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Unraveling the Complexity of Global Climate Dynamics:Interactions among El Niño-Southern Oscillation,Atlantic Meridional Overturning Circulation,and Tropical Basins Across Different Timescales
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作者 Aixue Hu Ingo Richter +11 位作者 Yuko Okumura Natalie Burls Noel Keenlyside Rhys Parfitt Katinka Bellomo Alessio Bellucci Riccardo Farneti Alexey VFedorov Brady SFerster Chengfei He Qian Li Daniela Matei 《Ocean-Land-Atmosphere Research》 2025年第3期306-333,共28页
Tropical basin interactions and the climatic linkages between mid-to-high latitudes and the tropics are active research areas.These interactions include the influence of El Niño-Southern Oscillation(ENSO)on the t... Tropical basin interactions and the climatic linkages between mid-to-high latitudes and the tropics are active research areas.These interactions include the influence of El Niño-Southern Oscillation(ENSO)on the tropical Indian and Atlantic oceans,the feedback from these basins on ENSO,the influence of the tropics on mid-to-high-latitude climates,and the feedback from higher latitudes on tropical climate variability.This review summarizes the current understanding of these relationships and key underlying physical processes. 展开更多
关键词 Tropics tropical basin interactions climatic linkages Mid High Latitudes Atlantic Meridional Overturning Circulation Climate Dynamics El Ni o Southern Oscillation Tropical Basins
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印太海温异常对中国冬季降水变化的调控关系
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作者 张文韬 伯玥 +2 位作者 李小兰 施红霞 王澄海 《高原气象》 北大核心 2026年第2期531-547,共17页
利用1961-2021年气象站观测的降水数据、ERA5再分析资料和海温资料,分析了中国冬季降水变化的时空特征及其与印度洋、太平洋海温异常的关系。结果表明,1961-2021年,中国冬季降水年际变率最大的东南沿海地区,冬季降水呈增加趋势[6.7 mm&#... 利用1961-2021年气象站观测的降水数据、ERA5再分析资料和海温资料,分析了中国冬季降水变化的时空特征及其与印度洋、太平洋海温异常的关系。结果表明,1961-2021年,中国冬季降水年际变率最大的东南沿海地区,冬季降水呈增加趋势[6.7 mm·(10a)^(-1)]。长江下游地区冬季降水年际变率次之,但降水增加最显著[9.6 mm·(10a)^(-1)]。这两个区域的冬季降水增加率均高于全国平均水平[1.5 mm·(10a)^(-1)]。中国冬季降水与印太海温异常关系密切。具体来说,赤道中东太平洋(Equatorial Central and Eastern Pacific,ECEP)和印度洋(Indian Ocean,IO)的海温异常,都与中国冬季降水存在显著的超前正相关关系,但其空间分布不同。夏、秋季ECEP海温异常与中国东南沿海冬季降水有显著正相关,冬季IO海温异常增强中国东南沿海降水和ECEP海温异常的正相关关系。IO海温异常和东南沿海冬季降水的正相关在秋季才出现,和中国北方冬季降水的正相关在春季便已经出现,冬季IO海温异常对中国北方冬季降水的影响独立于ECEP海温。前期夏、秋ECEP海温异常的不同演变,即El Niño和La Niña的不同演变对中国冬季降水的调控各异。夏季的El Niño如果持续到秋季,78%的年份中国冬季降水偏多;秋季出现La Niña并发展,则有83%的年份中国冬季降水偏少。夏季发生并持续到秋季的La Niña事件和秋季发生持续到冬季的El Niño事件对中国冬季降水的指示意义较弱。El Niño持续型(La Niña发展型),ECEP的850 hPa环流表现为异常东(西)风,在南海激发出气旋(反气旋)性异常环流,中国东南沿海受异常西南(东北)风影响,来自南海的水汽则异常偏多(少),水汽表现为辐合(辐散)性异常,该地区降水偏多(少)。IO海温异常通过激发西北太平洋异常环流,影响中国以北的冬季环流系统和从东向西输送的水汽,从而对中国冬季降水进行调控。因此,中国冬季降水的预测需要综合考虑ECEP海温和IO海温异常,尤其是赤道中东太平洋海温在夏、秋季的演变。 展开更多
关键词 冬季降水 时空变化 太平洋和印度洋海温信号 El Niño La Niña
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交错磁研究进展:材料物性与交叉应用
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作者 张瀚琦 赵骁驿 +5 位作者 王晶凯 徐泽东 吴勇 孟康康 徐晓光 姜勇 《物理学报》 北大核心 2026年第6期52-63,共12页
交错磁作为反铁磁材料的一个新兴研究分支,凭借其独特的对称性特征和非相对论性自旋劈裂,在实现Néel矢量的高效调控方面展现出显著优势,为自旋电子学器件的设计提供了新途径.本文基于自旋群对称性理论,首先阐释交错磁区别于传统反... 交错磁作为反铁磁材料的一个新兴研究分支,凭借其独特的对称性特征和非相对论性自旋劈裂,在实现Néel矢量的高效调控方面展现出显著优势,为自旋电子学器件的设计提供了新途径.本文基于自旋群对称性理论,首先阐释交错磁区别于传统反铁磁材料的电子结构特性;随后以MnTe和CrSb等典型材料体系为例,系统地综述了交错磁的制备方法及表征手段;接着梳理了利用电流脉冲、晶格应变和热激发等外场调控手段实现Néel矢量翻转与自旋-轨道力矩调制的机制与进展;并在此基础上对交错磁在磁随机存取存储器、拓扑自旋器件及磁子学、光-自旋耦合等多学科交叉领域的应用潜力进行了讨论;最后总结当前交错磁在材料体系拓展与对称性精确调控等方面面临的挑战,并对与其相关的界面工程等研究方向提出展望. 展开更多
关键词 交错磁材料 磁对称性 Néel矢量调控 反铁磁自旋电子学
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Proven performance,optimised costs–the new RE 6 EL
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《China Textile》 2026年第1期42-42,共1页
The new RE 6 EL from KARL MAYER brings a breath of fresh air to raschel fabric production.Nowadays textile companies increasingly need to produce small production runs and respond to market changes with instantaneous ... The new RE 6 EL from KARL MAYER brings a breath of fresh air to raschel fabric production.Nowadays textile companies increasingly need to produce small production runs and respond to market changes with instantaneous pattern changes in order to operate profitably–meaning they require machines that offer maximum flexibility,reliability and cost efficiency.KARL MAYER understands the challenges of the market and is launching its new RE 6 EL.The Raschel machine offers the core strengths of the classic RSE 6 EL and essentially the same performance parameters,but has been further cost-optimised largely due to local production advantages.This makes the newcomer an efficiency champion in production,especially when it comes to frequent pattern changes. 展开更多
关键词 raschel machine FLEXIBILITY PERFORMANCE re elthe rse el re el reliability cost efficiency
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Different effects of eastern and central Pacific El Niño events on the surface shortwave radiation over southern China in winter
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作者 Ming Cheng Ziniu Xiao +4 位作者 Xinyi Lai Jingjing Xu Siyu Lu Baorong Zhou Weisi Deng 《Atmospheric and Oceanic Science Letters》 2026年第1期27-33,共7页
This study investigates the distinct impacts of eastern Pacific(EP)and central Pacific(CP)El Niño events on winter shortwave solar radiation(SSR)in southern China,revealing different spatial distributions and und... This study investigates the distinct impacts of eastern Pacific(EP)and central Pacific(CP)El Niño events on winter shortwave solar radiation(SSR)in southern China,revealing different spatial distributions and underlying mechanisms.The results show that,during the developing winter of EP El Niño,significant SSR reductions occur in southwestern China and the east coast of southern China due to a strong,zonally extended Northwest Pacific anticyclone that transports moisture from the tropical Northwest Pacific and North Indian Ocean,while the northeast of southern China experiences a weak increase in SSR.In contrast,during the developing winter of CP El Niño,SSR decreases in the east of southern China with a significant decrease in the lower basin of the Yangtze River but an increase in the west of southern China with a remarkable increase in eastern Yunnan.The pronounced east-west dipole pattern in SSR anomalies is driven by a meridionally elongated Northwest Pacific anticyclone,which enhances northward moisture transport to the east of southern China while leaving western areas drier.Further research reveals that distinct moisture anomalies during the developing winter of EP and CP events result in divergent SSR distributions across southern China,primarily through modulating the total cloud cover.These findings highlight the critical need to differentiate between El Niño types when predicting medium and long-term variability of radiation in southern China. 展开更多
关键词 EP El Niño CP El Niño Shortwave solar radiation Northwest Pacific anticyclone Total cloud cover Total column water
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Macroscopic Quantum Tunneling and Coherence of the Néel Vector in Small Antiferromagnets
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作者 吕嵘 朱嘉麟 +1 位作者 陈曦 张礼 《Tsinghua Science and Technology》 SCIE EI CAS 1998年第4期1179-1183,共5页
The tunneling behavior of the Néel vector out of metastable easy directions or between degenerate easy directions is studied for a small single\|domain antiferromagnetic particle at low temperature. The quantum t... The tunneling behavior of the Néel vector out of metastable easy directions or between degenerate easy directions is studied for a small single\|domain antiferromagnetic particle at low temperature. The quantum tunneling rates for these processes are evaluated for two examples of macroscopic quantum tunneling and one example of macroscopic quantum coherence. The calculations are performed by using the two sublattice model and the instanton method in the spin coherent state path integral. Quantum interference or the spin parity effect is also discussed for each case. 展开更多
关键词 macroscopic quantum tunneling and coherence Néel vector antiferromagnetic particles topo\| logical term quantum interference effect
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大食物观背景下河南农村居民动物性食品消费结构研究
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作者 吕若冰 《全国流通经济》 2026年第6期4-8,共5页
为了研究河南农村居民动物性食品消费结构,本文利用2014—2022年动物性食品消费数据,采用ELES模型对河南农村居民动物性食品消费情况进行分析。结果表明:第一,农村居民对各类动物性食品的刚性需求数量均呈上升趋势。第二,除水产品的边... 为了研究河南农村居民动物性食品消费结构,本文利用2014—2022年动物性食品消费数据,采用ELES模型对河南农村居民动物性食品消费情况进行分析。结果表明:第一,农村居民对各类动物性食品的刚性需求数量均呈上升趋势。第二,除水产品的边际消费倾向呈现明显上升趋势外,各类动物性食品的边际消费倾向均大于零且较为稳定。第三,各市农村居民人均动物性食品消费量、消费结构差异较大。第四,各类动物性食品的需求收入弹性值均大于零。其中,猪牛羊肉、奶和奶制品的需求数量受收入的影响较大;水产品的需求收入弹性值呈波动式上升趋势。第五,各类动物性食品需求价格弹性值均小于零。其中,猪牛羊肉的需求价格弹性值较为稳定;家禽、蛋类及其制品、奶类及其制品的需求价格弹性绝对值呈下降趋势;而水产品的需求价格弹性绝对值则表现出上升趋势。基于以上分析结果,建议通过提高农民收入水平,保障动物性食品、特别是水产品等的有效供给等措施,促进河南农村居民家庭动物性食品合理消费。 展开更多
关键词 农村居民 消费结构 动物性食品 ELES模型
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基于正交实验的n型TOPCon电池正银印刷性能研究
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作者 贾艳飞 《丝网印刷》 2026年第5期29-31,共3页
研究以当前主流单晶n型TOPCon太阳能电池的网版印刷工艺为研究对象,采用正交实验方法评估了银浆印刷过程中印刷压力、回墨速度、网线宽度、稀释剂比例及电池温度等参数的影响程度,并确定了这些因素的最佳组合,同时对电池栅线的长宽比、... 研究以当前主流单晶n型TOPCon太阳能电池的网版印刷工艺为研究对象,采用正交实验方法评估了银浆印刷过程中印刷压力、回墨速度、网线宽度、稀释剂比例及电池温度等参数的影响程度,并确定了这些因素的最佳组合,同时对电池栅线的长宽比、湿重及电性能进行了测试。通过分析各参数变化对电池效率等性能指标的影响及其潜在机制,结果表明:控制El断栅的关键因素具有显著影响,其重要性排序为:印刷压力>稀释剂比例>回墨速度>电池温度>网线宽度。此外,印刷压力与稀释剂比例对电池电性能同样具有重要影响。 展开更多
关键词 n型TOPCon 正交实验 正银浆料 El断栅 电学性能
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2023年奔驰E350eL发动机故障灯点亮
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作者 梁新建 《汽车维修技师》 2026年第1期64-67,共4页
车型:2025年奔驰E350eL(插电式混合动力轿车),配置254.920发动机、725.121变速器。底盘号:214.154。VIN:LELG5EB9RL×××××××。行驶里程:1000km。故障现象:发动机启动后立即熄火,同时仪表提示安全气... 车型:2025年奔驰E350eL(插电式混合动力轿车),配置254.920发动机、725.121变速器。底盘号:214.154。VIN:LELG5EB9RL×××××××。行驶里程:1000km。故障现象:发动机启动后立即熄火,同时仪表提示安全气囊故障。经确认,此故障当前存在。问询客户得知,车辆在正常使用过程中突然出现该状况。故障诊断:经查询,车辆无相关维修历史。按照厂家文件指导可知,车辆未进行加装/改装。 展开更多
关键词 插电式混合动力轿车 发动机故障 奔驰E350eL
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Parallel-Data-Based Social Evolution Modeling
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作者 Weishan Zhang Zhaoxiang Hou +3 位作者 Xiao Wang Zhidong Xu Xin Liu Fei-Yue Wang 《Tsinghua Science and Technology》 SCIE EI CAS CSCD 2021年第6期878-885,共8页
Abnormal or drastic changes in the natural environment may lead to unexpected events,such as tsunamis and earthquakes,which are becoming a major threat to national economy.Currently,no effective assessment approach ca... Abnormal or drastic changes in the natural environment may lead to unexpected events,such as tsunamis and earthquakes,which are becoming a major threat to national economy.Currently,no effective assessment approach can deduce a situation and determine the optimal response strategy when a natural disaster occurs.In this study,we propose a social evolution modeling approach and construct a deduction model for self-playing,self-learning,and self-upgrading on the basis of the idea of parallel data and reinforcement learning.The proposed approach can evaluate the impact of an event,deduce the situation,and provide optimal strategies for decisionmaking.Taking the breakage of a submarine cable caused by earthquake as an example,we find that the proposed modeling approach can obtain a higher reward compared with other existing methods. 展开更多
关键词 paral el data reinforcement learning DECISION-MAKING
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2024年2月华东和华中大范围低温雨雪冰冻灾害的成因和可预报性分析 被引量:8
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作者 赵俊虎 赵语欣 +3 位作者 贾小龙 张涵 熊开国 曾宇星 《气象》 北大核心 2025年第1期17-29,共13页
利用全国2374个站点的逐日气温和降水资料、NCEP/NCAR大气环流再分析资料和Hadley中心的海温资料,研究了2024年2月华东和华中大范围低温雨雪冰冻灾害成因和可预报性。结果表明:2024年2月上旬和下旬这两次大范围低温雨雪冰冻天气过程,发... 利用全国2374个站点的逐日气温和降水资料、NCEP/NCAR大气环流再分析资料和Hadley中心的海温资料,研究了2024年2月华东和华中大范围低温雨雪冰冻灾害成因和可预报性。结果表明:2024年2月上旬和下旬这两次大范围低温雨雪冰冻天气过程,发生地区重叠度高,冰雪灾害严重;影响两次过程的副热带和中高纬环流系统配置较为一致,西北太平洋副热带高压(以下简称副高)稳定偏强和偏西,西伯利亚高压、南支槽和西北太平洋反气旋阶段性同步偏强,形成较强的协同作用,西伯利亚高压增强导致冷空气南下,副高、南支槽和西北太平洋反气旋同步增强则为华东和华中提供了充沛的水汽条件;2023年5月至2024年4月赤道中东太平洋地区发生了一次中等强度的El Nino事件,冬季热带印度洋和热带北大西洋海温异常偏暖,三大洋海温异常共同导致了副高持续偏强,也有利于西北太平洋反气旋的阶段性发展和增强,为2月的两次过程提供了充沛的水汽条件;次季节模式对两次过程的预报时效在1~2周左右,起报时间在2周以上时,目前模式无法准确预测欧亚中高纬环流系统的异常特征,导致对两次过程的预测能力较低。 展开更多
关键词 低温雨雪冻雨 El Nino 成因 次季节可预报性
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B_(el)亚型新等位基因(c.803G>T,p.Gly268Val)的家系研究
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作者 马晓莉 董文安 +3 位作者 杨贺才 耿明璐 王丽萍 于洋 《中国实验血液学杂志》 北大核心 2025年第2期504-510,共7页
目的:分析1个家系B_(el)亚型基因突变及其遗传机制。方法:通过血清学试验鉴定ABO血型,采用聚合酶链反应序列特异性引物(PCR-SSP)进行ABO基因分型,对ABO基因1-7外显子、侧翼内含子区域进行Sanger测序,7外显子单链测序确认突变点位置。利... 目的:分析1个家系B_(el)亚型基因突变及其遗传机制。方法:通过血清学试验鉴定ABO血型,采用聚合酶链反应序列特异性引物(PCR-SSP)进行ABO基因分型,对ABO基因1-7外显子、侧翼内含子区域进行Sanger测序,7外显子单链测序确认突变点位置。利用Missense3D软件预测该突变点导致的蛋白质结构改变。结果:常规血清学试验未能检测到先证者及其3个家族成员的红细胞B抗原,只能通过吸收放散试验发现有微量的B抗原表达。DNA分析显示,在正常ABO基因基础上,第7外显子803位置出现G>T替换,导致第268位氨基酸由Gly转变为Val。进一步单链测序分析发现该突变位点位于B基因上。结论:该家系中先证者及其父、其子、其女均因B基因第7外显子发生c.803G>T新的点突变导致B型糖基转移酶活性降低,B抗原只能通过吸收放散的方法才能够被检出,该点突变能够稳定遗传给子代。 展开更多
关键词 B_(el)亚型 ABO亚型 血清学 新等位基因 测序
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A hybrid coupled model for the tropical Pacific constructed by integrating ROMS with a statistical atmospheric model 被引量:2
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作者 Rong-Hua ZHANG Wenzhe ZHANG +4 位作者 Yang YU Yinnan LI Feng TIAN Chuan GAO Hongna WANG 《Journal of Oceanology and Limnology》 2025年第4期1037-1055,共19页
Numerical models are crucial for quantifying the ocean-atmosphere interactions associated with the El Niño-Southern Oscillation(ENSO)phenomenon in the tropical Pacific.Current coupled models often exhibit signifi... Numerical models are crucial for quantifying the ocean-atmosphere interactions associated with the El Niño-Southern Oscillation(ENSO)phenomenon in the tropical Pacific.Current coupled models often exhibit significant biases and inter-model differences in simulating ENSO,underscoring the need for alternative modeling approaches.The Regional Ocean Modeling System(ROMS)is a sophisticated ocean model widely used for regional studies and has been coupled with various atmospheric models.However,its application in simulating ENSO processes on a basin scale in the tropical Pacific has not been explored.For the first time,this study presents the development of a basin-scale hybrid coupled model(HCM)for the tropical Pacific,integrating ROMS with a statistical atmospheric model that captures the interannual relationships between sea surface temperature(SST)and wind stress anomalies.The HCM is evaluated for its capability to simulate the annual mean,seasonal,and interannual variations of the oceanic state in the tropical Pacific.Results demonstrate that the model effectively reproduces the ENSO cycle,with a dominant oscillation period of approximately two years.The ROMS-based HCM developed here offers an efficient and robust tool for investigating climate variability in the tropical Pacific. 展开更多
关键词 Regional Ocean Modeling System(ROMS) statistical atmospheric model hybrid coupled model El Niño-Southern Oscillation(ENSO) model evaluation tropical Pacific
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El Niño事件对长江中下游陆地水储量变化与洪水风险的影响
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作者 李晓英 暴一鸣 +1 位作者 陈伯文 张鹏辉 《长江科学院院报》 北大核心 2025年第12期41-50,共10页
为研究El Niño事件对长江中下游区域水资源变化的影响,利用不同研究机构发布的2003—2022年GRACE重力卫星数据获取研究区陆地水储量(TWSA)变化,对比相关系数、互相关关系结果,选择与东部型和中部型两类El Niño事件指数相关性... 为研究El Niño事件对长江中下游区域水资源变化的影响,利用不同研究机构发布的2003—2022年GRACE重力卫星数据获取研究区陆地水储量(TWSA)变化,对比相关系数、互相关关系结果,选择与东部型和中部型两类El Niño事件指数相关性强的CSR MASCON TWSA数据序列。利用小波分析、经验正交分解,同时引入洪水潜力指数,研究两类El Niño事件对研究区域TWSA的影响。结果表明:(1)在TWSA与东部型El Niño事件时滞6个月的情况下,两者相关性最大,相关系数达到0.630;TWSA峰值与东部型El Niño事件存在正向响应,与中部型El Niño事件响应不稳定。(2)交叉小波变换显示TWSA与两类El Niño事件之间存在共振周期;经验正交分解显示研究区域南部易受到两类El Niño事件影响。(3)空间栅格洪水潜力指数分布显示,两类El Niño事件发生后,研究区域南部产生的洪水风险较高;东部型El Niño事件对应研究区域洪水风险更大,分布较为集中;中部型El Niño事件对应研究区域洪水风险的分布较为分散。研究结果表明研究区域洪水风险与El Niño事件密切相关,El Niño事件对陆地水储量变化影响研究有助于对研究区域的洪水进行预测与防范。 展开更多
关键词 陆地水储量 El Niño事件 GRACE 小波分析 洪水潜力指数
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Applying joint species distribution modelling to assess the relative influence of ecological filters on community assembly in the El Bayadh steppe,Algeria
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作者 Patrick-Nino OLOUMANE Carlo PREVIL +1 位作者 Wael El ZEREY Asma El ZEREY-BELASKRI 《Journal of Arid Land》 2025年第7期979-996,共18页
Understanding plant community assembly is crucial for effective ecosystem conservation and restoration.The ecological filter framework describes community assembly as a process shaped by dispersal,environmental,and bi... Understanding plant community assembly is crucial for effective ecosystem conservation and restoration.The ecological filter framework describes community assembly as a process shaped by dispersal,environmental,and biotic filters.Additionally,functional traits and phylogenetic relationships are increasingly recognized as important factors influencing species coexistence and community structure.However,both the ecological filter framework and the roles of functional traits and phylogeny in community assembly remain underexplored in the Algerian steppes—particularly in the El Bayadh region,where ongoing vegetation degradation threatens ecosystem stability.This study applied Hierarchical Modeling of Species Communities(HMSC)as an integrative approach to assess how ecological filters influence plant community assembly in the El Bayadh steppe and to evaluate the roles of functional traits and phylogenetic relationships in this process.Environmental data—including soil properties,topography,precipitation,and land use types(grazing and exclosure)—were collected across 50 plots in April and October,2023,along with functional traits from 24 species.These traits include root length,leaf area,specific leaf area,clonality,life history,and seed mass.HMSC results revealed that soil properties and precipitation were the primary drivers of community structure,while sand height and elevation had a moderate influence.In contrast,competition and grazing played relatively minor roles.Species responses to environmental covariates were heterogeneous:soil fertility and texture had mixed effects,benefiting some species while limiting others;sand encroachment and precipitation variability generally had negative impacts,whereas grazing exclusion favored many species.A weak phylogenetic signal was recorded,indicating that community assembly was driven more by environmental filtering than by shared evolutionary history.Functional trait responses to environmental variation reflected plant strategies that balanced resource acquisition and conservation.Specifically,seed mass,leaf area,and root length increased under higher soil moisture and nutrient availability but declined in response to salinity,precipitation variability,and sand height.Clonality and perennial life history traits enhanced the survival of plant species under harsh conditions.Overall,this study provides a holistic understanding of community assembly processes in the El Bayadh steppe and offers valuable insights for ecosystem management and restoration in arid and degraded ecosystem environments. 展开更多
关键词 community assembly Hierarchical Modeling of Species Communities(HMSC) ecological filter functional traits PHYLOGENY conservation strategies El Bayadh steppe
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多尺度的轻量化光伏电池EL缺陷检测 被引量:1
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作者 孙铁强 赵成伟 +1 位作者 宋超 肖鹏程 《组合机床与自动化加工技术》 北大核心 2025年第3期177-181,186,共6页
针对光伏电池EL缺陷图像特点,提出了一种多尺度的轻量化光伏电池EL缺陷检测框架YOLOV8-GF。首先,采用轻量级特征提取网络HGNetV2作为骨干,并引入RepConv对其改进,增强多尺度特征融合能力;其次,提出自适应权重下采样(AFDS)方法,增强网络... 针对光伏电池EL缺陷图像特点,提出了一种多尺度的轻量化光伏电池EL缺陷检测框架YOLOV8-GF。首先,采用轻量级特征提取网络HGNetV2作为骨干,并引入RepConv对其改进,增强多尺度特征融合能力;其次,提出自适应权重下采样(AFDS)方法,增强网络对形态多变目标的处理能力;同时,改进头部采用共享参数结构并引入新型多尺度特征提取卷积(MLSA),减少参数冗余并提高特征提取能力;最后,使用Inner-IOU思想改进Shape-IOU提出Inner-Shape-IOU作为损失函数,提高网络鲁棒性。实验结果表明:在光伏电池EL缺陷数据集得到模型的参数量与计算量为2.41 M和5.8 GFLOPs,仅为YOLOv8n的77.4%和70.7%,mAP达到91.62%,较YOLOv8n提升1.4%。 展开更多
关键词 缺陷检测 YOLOv8 轻量化 光伏电池EL 多尺度
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赤道辐合带月平均位置的能量约束研究
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作者 黄炜充 赵树云 +2 位作者 马馨宇 王五科 邓琪敏 《热带气象学报》 北大核心 2025年第3期440-454,共15页
当前,不少研究提出在能量框架下理解赤道辐合带(ITCZ)的南北位置及移动。能量通量赤道(EFE)是能量框架下用于指示ITCZ位置的指标。已有研究发现,在年平均尺度上,EFE与ITCZ能很好地匹配,但在月尺度上情况如何,尚缺乏深入讨论。利用欧洲... 当前,不少研究提出在能量框架下理解赤道辐合带(ITCZ)的南北位置及移动。能量通量赤道(EFE)是能量框架下用于指示ITCZ位置的指标。已有研究发现,在年平均尺度上,EFE与ITCZ能很好地匹配,但在月尺度上情况如何,尚缺乏深入讨论。利用欧洲中期天气预报中心(ECMWF)的第五代再分析资料(ERA5)计算了1979—2021年逐月的ITCZ和EFE位置,并探讨了二者在月平均上的匹配关系。在计算ITCZ和EFE位置时,既采用了已有的计算方法,也提出了改进的方法。结果发现,在气候态月平均上,ITCZ与EFE在印度洋和海洋性大陆上匹配效果好,而在太平洋上较差,但新的EFE算法能在一定程度上改善太平洋上二者的匹配情况。在典型年份月平均(超强El Niño事件)中,ITCZ发生显著的南北位置异常,EFE能在一定程度上指示ITCZ的异常。通过ITCZ与EFE在不同月份和经度上的长期相关分析发现,二者在部分区域和月份具有显著的线性相关关系。结合850 hPa辐散风场、能量通量垂直积分辐散分量场,发现ITCZ与EFE在印度洋和海洋性大陆上匹配效果好的直接原因在于850 hPa环流的辐合位置(代表ITCZ)与能量通量的辐散位置(代表EFE)对应关系很好,而在太平洋上二者的位置有一定距离。结论说明,在月尺度上EFE在一定条件下可用于指示ITCZ的位置、季节变化和年际变化,即能量框架对研究ITCZ位置及其南北摆动具有一定的适用性,具体适用与否受到EFE算法、研究区域和季节的影响。 展开更多
关键词 赤道辐合带 能量框架 能量通量赤道 月尺度 超强El Niño
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