期刊文献+
共找到5,709篇文章
< 1 2 250 >
每页显示 20 50 100
引入上下文信息和Attention Gate的GUS-YOLO遥感目标检测算法 被引量:1
1
作者 张华卫 张文飞 +2 位作者 蒋占军 廉敬 吴佰靖 《计算机科学与探索》 CSCD 北大核心 2024年第2期453-464,共12页
目前基于通用YOLO系列的遥感目标检测算法存在并未充分利用图像的全局上下文信息,在特征融合金字塔部分并未充分考虑缩小融合特征之间的语义鸿沟、抑制冗余信息干扰的缺点。在结合YOLO算法优点的基础上提出GUS-YOLO算法,其拥有一个能够... 目前基于通用YOLO系列的遥感目标检测算法存在并未充分利用图像的全局上下文信息,在特征融合金字塔部分并未充分考虑缩小融合特征之间的语义鸿沟、抑制冗余信息干扰的缺点。在结合YOLO算法优点的基础上提出GUS-YOLO算法,其拥有一个能够充分利用全局上下文信息的骨干网络Global Backbone。除此之外,该算法在融合特征金字塔自顶向下的结构中引入Attention Gate模块,可以突出必要的特征信息,抑制冗余信息。另外,为Attention Gate模块设计了最佳的网络结构,提出了网络的特征融合结构U-Net。最后,为克服ReLU函数可能导致模型梯度不再更新的问题,该算法将Attention Gate模块的激活函数升级为可学习的SMU激活函数,提高模型鲁棒性。在NWPU VHR-10遥感数据集上,该算法相较于YOLOV7算法取得宽松指标mAP^(0.50)1.64个百分点和严格指标mAP^(0.75)9.39个百分点的性能提升。相较于目前主流的七种检测算法,该算法取得较好的检测性能。 展开更多
关键词 遥感图像 Global Backbone Attention Gate SMU U-neck
下载PDF
企业高质量发展视角下上市公司内部控制效率评价
2
作者 池国华 蒋志远 《财会月刊》 北大核心 2024年第1期19-26,共8页
内部控制评价对于企业自我完善和发展至关重要,但我国企业内部控制评价难以满足企业高质量发展需要,这主要是由于缺少科学的评价思路和方法。本文基于系统观构建内部控制效率评价指标体系,并运用网络DEA模型与Global Malmquist指数对201... 内部控制评价对于企业自我完善和发展至关重要,但我国企业内部控制评价难以满足企业高质量发展需要,这主要是由于缺少科学的评价思路和方法。本文基于系统观构建内部控制效率评价指标体系,并运用网络DEA模型与Global Malmquist指数对2019~2021年我国1653家制造业A股非∗ST上市公司的内部控制效率进行实证分析。结果表明:应用网络DEA模型构建的内部控制效率指数更符合企业高质量发展的要求。分析发现,企业的内部环境、风险评估和控制活动效率易受外部环境影响,内部控制效率提升依赖于企业对相关规范的应用能力。此外,内部控制效率与企业资产规模、成立年限和股权制衡度负相关,与独立董事比例、机构投资者持股比例和管理层持股比例正相关,且非国有企业比国有企业具有更高的内部控制效率。这些发现验证了网络DEA模型在评价上市公司内部控制效率方面的科学性和合理性,为企业内部控制的改进提供了明确的方向和依据。 展开更多
关键词 高质量发展 内部控制效率 系统观 网络DEA Global Malmquist指数
下载PDF
融合RoBERTa-WWM和全局指针网络的农业病害实体关系联合抽取研究
3
作者 王彤 张立杰 +4 位作者 王铭 吴华瑞 朱华吉 杨英茹 王春山 《河北农业大学学报》 CAS CSCD 北大核心 2024年第3期113-120,129,共9页
针对实体和关系抽取过程中存在的一词多义、实体嵌套、三元组重叠的问题,本文提出了1种融合RoBERTa-WWM和全局指针网络的联合抽取模型RBGPL。该模型引入RoBERTa-WWM预训练模型,利用上下文的语境信息融合克服了不同语境下一词多义问题;... 针对实体和关系抽取过程中存在的一词多义、实体嵌套、三元组重叠的问题,本文提出了1种融合RoBERTa-WWM和全局指针网络的联合抽取模型RBGPL。该模型引入RoBERTa-WWM预训练模型,利用上下文的语境信息融合克服了不同语境下一词多义问题;采用全局指针网络Global pointer标注方式解决了实体嵌套问题;通过全局指针联合解码模型将三重抽取转变为五重提取,解决了三元组重叠问题。在自建农业病害数据集上,模型RBGPL的精确率、召回率、F1值达到76.23%,91.18%,83.04%,与其他联合抽取模型相对比F1值均取最优,有效地克服了一词多义问题和三元组重叠问题。此外,在病原(Pathogeny)和作物名称(Crop)2种易嵌套实体的F1值上提升了3%和18%,实体嵌套得到了显著缓解。本文方法提高了中文农业病害领域实体关系抽取性能,可为农业病害领域知识图谱的构建提供技术支持。 展开更多
关键词 农业病害 联合抽取 RoBERTa-WWM Global pointer
下载PDF
A Study on the Transmission Dynamics of the Omicron Variant of COVID-19 Using Nonlinear Mathematical Models 被引量:1
4
作者 S.Dickson S.Padmasekaran +2 位作者 Pushpendra Kumar Kottakkaran Sooppy Nisar Hamidreza Marasi 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期2265-2287,共23页
This research examines the transmission dynamics of the Omicron variant of COVID-19 using SEIQIcRVW and SQIRV models,considering the delay in converting susceptible individuals into infected ones.The significant delay... This research examines the transmission dynamics of the Omicron variant of COVID-19 using SEIQIcRVW and SQIRV models,considering the delay in converting susceptible individuals into infected ones.The significant delays eventually resulted in the pandemic’s containment.To ensure the safety of the host population,this concept integrates quarantine and the COVID-19 vaccine.We investigate the stability of the proposed models.The fundamental reproduction number influences stability conditions.According to our findings,asymptomatic cases considerably impact the prevalence of Omicron infection in the community.The real data of the Omicron variant from Chennai,Tamil Nadu,India,is used to validate the outputs. 展开更多
关键词 Omicron local stability reproduction number steady states global stability
下载PDF
GLOBAL SOLUTIONS TO 1D COMPRESSIBLE NAVIER-STOKES/ALLEN-CAHN SYSTEM WITH DENSITY-DEPENDENT VISCOSITY AND FREE-BOUNDARY 被引量:1
5
作者 丁时进 李颖花 王喻 《Acta Mathematica Scientia》 SCIE CSCD 2024年第1期195-214,共20页
This paper is concerned with the Navier-Stokes/Allen-Cahn system,which is used to model the dynamics of immiscible two-phase flows.We consider a 1D free boundary problem and assume that the viscosity coefficient depen... This paper is concerned with the Navier-Stokes/Allen-Cahn system,which is used to model the dynamics of immiscible two-phase flows.We consider a 1D free boundary problem and assume that the viscosity coefficient depends on the density in the form ofη(ρ)=ρ^(α).The existence of unique global H^(2m)-solutions(m∈N)to the free boundary problem is proven for when 0<α<1/4.Furthermore,we obtain the global C^(∞)-solutions if the initial data is smooth. 展开更多
关键词 Navier-Stokes/Allen-Cahn system density-dependent viscosity free boundary global solutions
下载PDF
Global hybrid simulations of soft X-ray emissions in the Earth’s magnetosheath 被引量:1
6
作者 Jin Guo TianRan Sun +6 位作者 San Lu QuanMing Lu Yu Lin XueYi Wang Chi Wang RongSheng Wang Kai Huang 《Earth and Planetary Physics》 EI CSCD 2024年第1期47-58,共12页
Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas,and it is also the boundary of the solar wind energy transport to the magnetosphere.Soft X-ray imaging ... Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas,and it is also the boundary of the solar wind energy transport to the magnetosphere.Soft X-ray imaging allows investigation of the large-scale magnetopause by providing a two-dimensional(2-D)global view from a satellite.By performing 3-D global hybrid-particle-in-cell(hybrid-PIC)simulations,we obtain soft X-ray images of Earth’s magnetopause under different solar wind conditions,such as different plasma densities and directions of the southward interplanetary magnetic field.In all cases,magnetic reconnection occurs at low latitude magnetopause.The soft X-ray images observed by a hypothetical satellite are shown,with all of the following identified:the boundary of the magnetopause,the cusps,and the magnetosheath.Local X-ray emissivity in the magnetosheath is characterized by large amplitude fluctuations(up to 160%);however,the maximum line-of-sight-integrated X-ray intensity matches the tangent directions of the magnetopause well,indicating that these fluctuations have limited impact on identifying the magnetopause boundary in the X-ray images.Moreover,the magnetopause boundary can be identified using multiple viewing geometries.We also find that solar wind conditions have little effect on the magnetopause identification.The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission will provide X-ray images of the magnetopause for the first time,and our global hybrid-PIC simulation results can help better understand the 2-D X-ray images of the magnetopause from a 3-D perspective,with particle kinetic effects considered. 展开更多
关键词 MAGNETOPAUSE X-ray emissivity X-ray imaging SMILE global hybrid-PIC simulation
下载PDF
Background removal from global auroral images:Data-driven dayglow modeling 被引量:1
7
作者 A.Ohma M.Madelaire +4 位作者 K.M.Laundal J.P.Reistad S.M.Hatch S.Gasparini S.J.Walker 《Earth and Planetary Physics》 EI CSCD 2024年第1期247-257,共11页
Global images of auroras obtained by cameras on spacecraft are a key tool for studying the near-Earth environment.However,the cameras are sensitive not only to auroral emissions produced by precipitating particles,but... Global images of auroras obtained by cameras on spacecraft are a key tool for studying the near-Earth environment.However,the cameras are sensitive not only to auroral emissions produced by precipitating particles,but also to dayglow emissions produced by photoelectrons induced by sunlight.Nightglow emissions and scattered sunlight can contribute to the background signal.To fully utilize such images in space science,background contamination must be removed to isolate the auroral signal.Here we outline a data-driven approach to modeling the background intensity in multiple images by formulating linear inverse problems based on B-splines and spherical harmonics.The approach is robust,flexible,and iteratively deselects outliers,such as auroral emissions.The final model is smooth across the terminator and accounts for slow temporal variations and large-scale asymmetries in the dayglow.We demonstrate the model by using the three far ultraviolet cameras on the Imager for Magnetopause-to-Aurora Global Exploration(IMAGE)mission.The method can be applied to historical missions and is relevant for upcoming missions,such as the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission. 展开更多
关键词 AURORA dayglow modeling global auroral images far ultraviolet images dayglow removal
下载PDF
Assessment of International GNSS Service Global Ionosphere Map products over China region based on measurements from the Crustal Movement Observation Network of China 被引量:1
8
作者 Jin Hu HaiBing Ruan +2 位作者 FuQing Huang ShengYang Gu XianKang Dou 《Earth and Planetary Physics》 EI CAS CSCD 2024年第2期400-407,共8页
The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of G... The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of GIM products in data-sparse regions is of paramount importance.In this study,measurements from the Crustal Movement Observation Network of China(CMONOC)are leveraged to evaluate the suitability of IGS-GIM products over China region in 2013-2014.The indices of mean error(ME),root mean square error(RMSE),and normalized RMSE(NRMSE)are then utilized to quantify the accuracy of IGS-GIM products.Results revealed distinct local time and latitudinal dependencies in IGS-GIM errors,with substantially high errors at nighttime(NRMSE:39%)and above 40°latitude(NRMSE:49%).Seasonal differences also emerged,with larger equinoctial deviations(NRMSE:33.5%)compared with summer(20%).A preliminary analysis implied that the irregular assimilation of sparse IGS observations,compounded by China’s distinct geomagnetic topology,may manifest as error variations.These results suggest that modeling based solely on IGS-GIM observations engenders inadequate representations across China and that a thorough examination would proffer the necessary foundation for advancing regional total electron content(TEC)constructions. 展开更多
关键词 International GNSS Service(IGS)Global Ionosphere Maps(GIM) Crustal Movement Observation Network of China(CMONOC) total electron content(TEC) data assessment
下载PDF
El Niño and the AMO Sparked the Astonishingly Large Margin of Warming in the Global Mean Surface Temperature in 2023
9
作者 Kexin LI Fei ZHENG +1 位作者 Jiang ZHU Qing-Cun ZENG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第6期1017-1022,共6页
In 2023,the majority of the Earth witnessed its warmest boreal summer and autumn since 1850.Whether 2023 will indeed turn out to be the warmest year on record and what caused the astonishingly large margin of warming ... In 2023,the majority of the Earth witnessed its warmest boreal summer and autumn since 1850.Whether 2023 will indeed turn out to be the warmest year on record and what caused the astonishingly large margin of warming has become one of the hottest topics in the scientific community and is closely connected to the future development of human society.We analyzed the monthly varying global mean surface temperature(GMST)in 2023 and found that the globe,the land,and the oceans in 2023 all exhibit extraordinary warming,which is distinct from any previous year in recorded history.Based on the GMST statistical ensemble prediction model developed at the Institute of Atmospheric Physics,the GMST in 2023 is predicted to be 1.41℃±0.07℃,which will certainly surpass that in 2016 as the warmest year since 1850,and is approaching the 1.5℃ global warming threshold.Compared to 2022,the GMST in 2023 will increase by 0.24℃,with 88%of the increment contributed by the annual variability as mostly affected by El Niño.Moreover,the multidecadal variability related to the Atlantic Multidecadal Oscillation(AMO)in 2023 also provided an important warming background for sparking the GMST rise.As a result,the GMST in 2023 is projected to be 1.15℃±0.07℃,with only a 0.02℃ increment,if the effects of natural variability—including El Niño and the AMO—are eliminated and only the global warming trend is considered. 展开更多
关键词 record-breaking temperature global mean surface temperature El Niño AMO global warming
下载PDF
New Record Ocean Temperatures and Related Climate Indicators in 2023
10
作者 Lijing CHENG John ABRAHAM +31 位作者 Kevin ETRENBERTH Tim BOYER Michael EMANN Jiang ZHU Fan WANG Fujiang YU Ricardo LOCARNINI John FASULLO Fei ZHENG Yuanlong LI Bin ZHANG Liying WAN Xingrong CHEN Dakui WANG Licheng FENG Xiangzhou SONG Yulong LIU Franco RESEGHETTI Simona SIMONCELLI Viktor GOURETSKI Gengxin CHEN Alexey MISHONOV Jim REAGAN Karina VON SCHUCKMANN Yuying PAN Zhetao TAN Yujing ZHU Wangxu WEI Guancheng LI Qiuping REN Lijuan CAO Yayang LU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第6期1068-1082,共15页
The global physical and biogeochemical environment has been substantially altered in response to increased atmospheric greenhouse gases from human activities.In 2023,the sea surface temperature(SST)and upper 2000 m oc... The global physical and biogeochemical environment has been substantially altered in response to increased atmospheric greenhouse gases from human activities.In 2023,the sea surface temperature(SST)and upper 2000 m ocean heat content(OHC)reached record highs.The 0–2000 m OHC in 2023 exceeded that of 2022 by 15±10 ZJ(1 Zetta Joules=1021 Joules)(updated IAP/CAS data);9±5 ZJ(NCEI/NOAA data).The Tropical Atlantic Ocean,the Mediterranean Sea,and southern oceans recorded their highest OHC observed since the 1950s.Associated with the onset of a strong El Niño,the global SST reached its record high in 2023 with an annual mean of~0.23℃ higher than 2022 and an astounding>0.3℃ above 2022 values for the second half of 2023.The density stratification and spatial temperature inhomogeneity indexes reached their highest values in 2023. 展开更多
关键词 ocean heat content SALINITY STRATIFICATION global warming CLIMATE
下载PDF
Glycolysis and glucose metabolism as a target for bioenergetic and neuronal protection in glaucoma
11
作者 Pete A.Williams Robert J.Casson 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第8期1637-1638,共2页
Vision is arguably our most valued sense,yet approximately 340 million people globally suffer blindness or moderate visual impairment,highlighting the need to further develop and advance treatments for ophthalmic dise... Vision is arguably our most valued sense,yet approximately 340 million people globally suffer blindness or moderate visual impairment,highlighting the need to further develop and advance treatments for ophthalmic diseases.Glaucoma refers to a group of ocular disorders united by a clinically characteristic optic neuropathy with associated retinal ganglion cell loss. 展开更多
关键词 METABOLISM GLAUCOMA globally
下载PDF
Targeting calcium signaling in Alzheimer’s disease: challenges and promising therapeutic avenues
12
作者 LinLin Song YongPei Tang Betty Yuen Kwan Law 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第3期501-502,共2页
The critical role of calcium dyshomeostasis in the pathogenesis of Alzheimer’s disease(AD):AD is a progressive neurodegenerative disease characterized by cognitive decline,memory impairment,and behavioral changes.Wit... The critical role of calcium dyshomeostasis in the pathogenesis of Alzheimer’s disease(AD):AD is a progressive neurodegenerative disease characterized by cognitive decline,memory impairment,and behavioral changes.With an estimated 50 million people being affected worldwide,the incidence of AD is constantly increasing globally.The hallmark of AD is the accumulation of amyloid-beta protein(Aβ)in the form of amyloid plaques and hyperphosphorylated tau protein in the form of neurofibrillary tangles.However,increasing evidence suggests that calcium ion(Ca2+)dysregulation also plays a crucial role in the pathogenesis of AD(Calvo-Rodriguez and Bacskai,2021).As a key second messenger,Ca2+regulates a wide range of cellular processes,including the release of neurotransmitters,gene expression,and cell death.Ca^(2+)also regulates the activity of Calcium/calmodulin-dependent protein kinase II,which is critical for synaptic plasticity,learning,and memory(Kaushik et al.,2022).Alternation in the Ca^(2+)signal is an early event in the pathogenesis of AD,which can lead to synaptic dysfunction,neuronal loss,and cognitive impairment. 展开更多
关键词 ALZHEIMER HOMEOSTASIS globally
下载PDF
Recent advances and future therapy development for Alzheimer’s disease and related disorders
13
作者 Megan Hong Gal Bitan 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第9期1877-1878,共2页
Over 55 million people globally live with Alzheimer’s disease(AD)or related dementias(ADRD)and the number is expected to double every twenty years.Unt i l recent l y,onl y symptomatic treatments were available to pat... Over 55 million people globally live with Alzheimer’s disease(AD)or related dementias(ADRD)and the number is expected to double every twenty years.Unt i l recent l y,onl y symptomatic treatments were available to patients with AD,including acetylcholine esterase inhibitors,of which the last one,galantamine,was approved by the US Food and Drug Administration(FDA)in 2001. 展开更多
关键词 ALZHEIMER globally patients
下载PDF
GLOBAL WEAK SOLUTIONS FOR AN ATTRACTION-REPULSION CHEMOTAXIS SYSTEM WITH p-LAPLACIAN DIFFUSION AND LOGISTIC SOURCE
14
作者 王晓闪 王忠谦 贾哲 《Acta Mathematica Scientia》 SCIE CSCD 2024年第3期909-924,共16页
This paper is concerned with the following attraction-repulsion chemotaxis system with p-Laplacian diffusion and logistic source:■The system here is under a homogenous Neumann boundary condition in a bounded domainΩ... This paper is concerned with the following attraction-repulsion chemotaxis system with p-Laplacian diffusion and logistic source:■The system here is under a homogenous Neumann boundary condition in a bounded domainΩ ■ R^(n)(n≥2),with χ,ξ,α,β,γ,δ,k_(1),k_(2)> 0,p> 2.In addition,the function f is smooth and satisfies that f(s)≤κ-μs~l for all s≥0,with κ ∈ R,μ> 0,l> 1.It is shown that(ⅰ)if l> max{2k_(1),(2k_(1)n)/(2+n)+1/(p-1)},then system possesses a global bounded weak solution and(ⅱ)if k_(2)> max{2k_(1)-1,(2k_(1)n)/(2+n)+(2-p)/(p-1)} with l> 2,then system possesses a global bounded weak solution. 展开更多
关键词 global weak solutions attraction-repulsion P-LAPLACIAN logistic source
下载PDF
Human brain organoid:trends,evolution,and remaining challenges
15
作者 Minghui Li Yuhan Yuan +3 位作者 Zongkun Hou Shilei Hao Liang Jin Bochu Wang 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第11期2387-2399,共13页
Advanced brain organoids provide promising platforms for deciphering the cellular and molecular processes of human neural development and diseases.Although various studies and reviews have described developments and a... Advanced brain organoids provide promising platforms for deciphering the cellular and molecular processes of human neural development and diseases.Although various studies and reviews have described developments and advancements in brain organoids,few studies have comprehensively summarized and analyzed the global trends in this area of neuroscience.To identify and further facilitate the development of cerebral organoids,we utilized bibliometrics and visualization methods to analyze the global trends and evolution of brain organoids in the last 10 years.First,annual publications,countries/regions,organizations,journals,authors,co-citations,and keywords relating to brain organoids were identified.The hotspots in this field were also systematically identified.Subsequently,current applications for brain organoids in neuroscience,including human neural development,neural disorders,infectious diseases,regenerative medicine,drug discovery,and toxicity assessment studies,are comprehensively discussed.Towards that end,several considerations regarding the current challenges in brain organoid research and future strategies to advance neuroscience will be presented to further promote their application in neurological research. 展开更多
关键词 bibliometric analysis brain organoids cerebral organoids global trends NEUROSCIENCE
下载PDF
Quantifying the agreement and accuracy characteristics of four satellite-based LULC products for cropland classification in China
16
作者 Jie Xue Xianglin Zhang +3 位作者 Songchao Chen Bifeng Hu Nan Wang Zhou Shi 《Journal of Integrative Agriculture》 SCIE CSCD 2024年第1期283-297,共15页
Various land use and land cover(LULC)products have been produced over the past decade with the development of remote sensing technology.Despite the differences in LULC classification schemes,there is a lack of researc... Various land use and land cover(LULC)products have been produced over the past decade with the development of remote sensing technology.Despite the differences in LULC classification schemes,there is a lack of research on assessing the accuracy of their application to croplands in a unified framework.Thus,this study evaluated the spatial and area accuracies of cropland classification for four commonly used global LULC products(i.e.,MCD12Q1V6,GlobCover2009,FROM-GLC and GlobeLand30)based on the harmonised FAO criterion,and quantified the relationships between four factors(i.e.,slope,elevation,field size and crop system)and cropland classification agreement.The validation results indicated that MCD12Q1 and GlobeLand30 performed well in cropland classification regarding spatial consistency,with overall accuracies of 94.90 and 93.52%,respectively.The FROMGLC showed the worst performance,with an overall accuracy of 83.17%.Overlaying the cropland generated by the four global LULC products,we found the proportions of complete agreement and disagreement were 15.51 and 44.72% for the cropland classification,respectively.High consistency was mainly observed in the Northeast China Plain,the Huang-Huai-Hai Plain and the northern part of the Middle-lower Yangtze Plain,China.In contrast,low consistency was detected primarily on the eastern edge of the northern and semiarid region,the Yunnan-Guizhou Plateau and southern China.Field size was the most important factor for mapping cropland.For area accuracy,compared with China Statistical Yearbook data at the provincial scale,the accuracies of different products in descending order were:GlobeLand30,FROM-GLC,MCD12Q1,and GlobCover2009.The cropland classification schemes mainly caused large area deviations among the four products,and they also resulted in the different ranks of spatial accuracy and area accuracy among the four products.Our results can provide valuable suggestions for selecting cropland products at the national or provincial scale and help cropland mapping and reconstruction,which is essential for food security and crop management,so they can also contribute to achieving the Sustainable Development Goals issued by the United Nations. 展开更多
关键词 global LULC products cropland mapping accuracy evaluation food security China
下载PDF
A global model of intensity autocorrelation to determine laser pulse duration
17
作者 彭雨菲 刘励强 +1 位作者 洪丽红 李志远 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期446-451,共6页
We present a new global model of collinear autocorrelation based on second harmonic generation nonlinearity.The model is rigorously derived from the nonlinear coupled wave equation specific to the autocorrelation meas... We present a new global model of collinear autocorrelation based on second harmonic generation nonlinearity.The model is rigorously derived from the nonlinear coupled wave equation specific to the autocorrelation measurement configuration,without requiring a specific form of the incident pulse function.A rigorous solution of the nonlinear coupled wave equation is obtained in the time domain and expressed in a general analytical form.The global model fully accounts for the nonlinear interaction and propagation effects within nonlinear crystals,which are not captured by the classical local model.To assess the performance of the global model compared to the classic local model,we investigate the autocorrelation signals obtained from both models for different incident pulse waveforms and different full-widthes at half-maximum(FWHMs).When the incident pulse waveform is Lorentzian with an FWHM of 200 fs,the global model predicts an autocorrelation signal FWHM of 399.9 fs,while the classic local model predicts an FWHM of 331.4 fs.The difference between the two models is 68.6 fs,corresponding to an error of 17.2%.Similarly,for a sech-type incident pulse with an FWHM of 200 fs,the global model predicts an autocorrelation signal FWHM of 343.9 fs,while the local model predicts an FWHM of 308.8 fs.The difference between the two models is 35.1 fs,with an error of 10.2%.We further examine the behavior of the models for Lorentzian pulses with FWHMs of 100 fs,200 fs and 500 fs.The differences between the global and local models are 17.1 fs,68.6 fs and 86.0 fs,respectively,with errors approximately around 17%.These comparative analyses clearly demonstrate the superior accuracy of the global model in intensity autocorrelation modeling. 展开更多
关键词 intensity autocorrelation global model ultrashort pulses pulse-width measurement
下载PDF
Information for Authors
18
《Water Science and Engineering》 EI CAS CSCD 2024年第1期F0003-F0003,共1页
Water Science and Engineering(WSE),founded in 2008,is a scientific and technical periodical published quarterly in English and distributed globally.The journal is sponsored by Hohai University and the State Key Labora... Water Science and Engineering(WSE),founded in 2008,is a scientific and technical periodical published quarterly in English and distributed globally.The journal is sponsored by Hohai University and the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering of China. 展开更多
关键词 JOURNAL China. globally
下载PDF
THE GLOBAL EXISTENCE AND ANALYTICITY OF A MILD SOLUTION TO THE 3D REGULARIZED MHD EQUATIONS
19
作者 肖存涛 邱华 姚正安 《Acta Mathematica Scientia》 SCIE CSCD 2024年第3期973-983,共11页
In this paper,we study the three-dimensional regularized MHD equations with fractional Laplacians in the dissipative and diffusive terms.We establish the global existence of mild solutions to this system with small in... In this paper,we study the three-dimensional regularized MHD equations with fractional Laplacians in the dissipative and diffusive terms.We establish the global existence of mild solutions to this system with small initial data.In addition,we also obtain the Gevrey class regularity and the temporal decay rate of the solution. 展开更多
关键词 regularized MHD equations fractional Laplacian global well-posedness ANALYTICITY decay rate
下载PDF
Using satellite-derived land surface temperatures to clarify the spatiotemporal warming trends of the Alborz Mountains in northern Iran
20
作者 ROSHAN Gholamreza SARLI Reza +2 位作者 GHANGHERMEH Abdolazim TAHERIZADEH Mehrnoosh NIKNAM Arman 《Journal of Mountain Science》 SCIE CSCD 2024年第2期449-469,共21页
The Alborz Mountains are some of the highest in Iran,and they play an important role in controlling the climate of the country’s northern regions.The land surface temperature(LST)is an important variable that affects... The Alborz Mountains are some of the highest in Iran,and they play an important role in controlling the climate of the country’s northern regions.The land surface temperature(LST)is an important variable that affects the ecosystem of this area.This study investigated the spatiotemporal changes and trends of the nighttime LST in the western region of the Central Alborz Mountains at elevations of 1500-4000 m above sea level.MODIS data were extracted for the period of 2000-2021,and the Mann-Kendall nonparametric test was applied to evaluating the changes in the LST.The results indicated a significant increasing trend for the monthly average LST in May-August along the southern aspect.Both the northern and southern aspects showed decreasing trends for the monthly average LST in October,November,and March and an increasing trend in other months.At all elevations,the average decadal change in the monthly average LST was more severe along the southern aspect(0.60°C)than along the northern aspect(0.37°C).The LST difference between the northern and southern aspects decreased in the cold months but increased in the hot months.At the same elevation,the difference in the lapse rate between the northern and southern aspects was greater in the hot months than in the cold months.With increasing elevation,the lapse rate between the northern and southern aspects disappeared.Climate change was concluded to greatly decrease the difference in LST at different elevations for April-July. 展开更多
关键词 Global warming Mountainous areas Lapse rate Surface air temperatures ALBORZ
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部