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Genetically-and environmentally-dependent processes drive interspecific and intraspecific divergence in the Chinese relict endemic genus Dipteronia
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作者 Tao Zhou Xiaodan Chen +6 位作者 Jordi López-Pujol Guoqing Bai Sonia Herrando-Moraira Neus Nualart Xiao Zhang Yuemei Zhao Guifang Zhao 《Plant Diversity》 SCIE CAS CSCD 2024年第5期585-599,共15页
China is a hotspot of relict plant species that were once widespread throughout the Northern Hemisphere.Recent research has demonstrated that the occurrence of long-term stable refugia in the mountainous regions of ce... China is a hotspot of relict plant species that were once widespread throughout the Northern Hemisphere.Recent research has demonstrated that the occurrence of long-term stable refugia in the mountainous regions of central and south-western China allowed their persistence through the late Neogene climate fluctuations.One of these relict lineages is Dipteronia,an oligotypic tree genus with a fossil record extending to the Paleocene.Here,we investigated the genetic variability,demographic dynamics and diversification patterns of the two currently recognized Dipteronia species(Dipteronia sinensis and D.dyeriana).Molecular data were obtained from 45 populations of Dipteronia by genotyping three cpDNA regions,two single copy nuclear genes and 15 simple sequence repeat loci.The genetic study was combined with niche comparison analyses on the environmental space,ecological niche modeling,and landscape connectivity analysis.We found that the two Dipteronia species have highly diverged both in genetic and ecological terms.Despite the incipient speciation processes that can be observed in D.sinensis,the occurrence of long-term stable refugia and,particularly,a dispersal corridor along Daba Shan-west Qinling,likely ensured its genetic and ecological integrity to date.Our study will not only help us to understand how populations of Dipteronia species responded to the tectonic and climatic changes of the Cenozoic,but also provide insight into how Arcto-Tertiary relict plants in East Asia survived,evolved,and diversified. 展开更多
关键词 Dipteronia Interspecific/intraspecific divergence Genetic structure Climatic niche divergence Dispersal corridor
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A new species of Discostella guiyangensis sp.nov.(Bacillariophyta,Stephanodiscales)from Guiyang,China:morphology and phylogeny
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作者 Yandan XIANG Fangru NAN +3 位作者 Xudong LIU Shulian XIE John Patrick KOCIOLEK Qi LIU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第4期1312-1324,共13页
We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations,as well as molecular analysis.This species is morphologically distinguished from other species by a r... We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations,as well as molecular analysis.This species is morphologically distinguished from other species by a relatively smooth and slightly recessed central area with marginal striae of unequal lengths forked near the margin.Marginal fultoportulae and a single rimoportula are situated between every two costae or on the costae.Both morphological characters and the concatenated data of rbc L and SSU rDNA indicate that Discostella guiyangensis is a unique and new species.According to divergence time estimation analysis,Discostella guiyangensis is the oldest species among the Discostella species sequenced currently.In addition,we complement molecular data of Discostella asterocostata and Discostella stelligera. 展开更多
关键词 Discostella MORPHOLOGY molecular analysis divergence time estimation new species
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Influence of Transportation Accessibility on Urban-rural Income Disparity and Its Spatial Heterogeneity
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作者 HUANG Xiaoyan KANG Chenchen +1 位作者 YIN Chun TANG Junqing 《Chinese Geographical Science》 SCIE CSCD 2024年第3期453-467,共15页
Transportation accessibility has been treated as an important means of reducing the urban-rural income disparity.However,only a few studies have examined the effects of different types of transportation accessibility ... Transportation accessibility has been treated as an important means of reducing the urban-rural income disparity.However,only a few studies have examined the effects of different types of transportation accessibility on urban-rural income disparity and their spatial heterogeneity.Based on data from 285 prefecture-level(and above)Chinese cities in 2000,2005,2010,2015,and 2020,this study uses spatial econometric models to examine how highway accessibility and railway accessibility influence the urban-rural income disparity and to identify their spatial heterogeneity.The result reveals that highway accessibility and railway accessibility have‘coreperiphery’ring-like circle structures.The urban-rural income disparity exhibits strong spatial clustering effects.Both highway accessibility and railway accessibility are negatively associated with urban-rural income disparity,and the former having a greater effect size.Moreover,there is a substitution effect between highway accessibility and railway accessibility in the whole sample.Furthermore,these associations differ in geographic regions.In the central region,highway accessibility is more important in reducing the urban-rural income disparity,but its effect is weakened with the increase of railway accessibility.In the western region,railway accessibility has a larger effect on narrowing the urban-rural income disparity,and this effect is strengthened by the increase of highway accessibility.We conclude that improving transportation accessibility is conducive to reducing the urban-rural income disparity but its effect is spatial heterogenetic.Highways and railways should be developed in a coordinated manner to promote an integrated transport network system. 展开更多
关键词 transport accessibility income gap regional divergence spatial heterogeneity urban and rural areas China
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ELLIPTIC EQUATIONS IN DIVERGENCE FORM WITH DISCONTINUOUS COEFFICIENTS IN DOMAINS WITH CORNERS
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作者 Jun CHEN Xuemei DENG 《Acta Mathematica Scientia》 SCIE CSCD 2024年第5期1903-1915,共13页
We study equations in divergence form with piecewise Cαcoefficients.The domains contain corners and the discontinuity surfaces are attached to the edges of the corners.We obtain piecewise C^(1,α) estimates across th... We study equations in divergence form with piecewise Cαcoefficients.The domains contain corners and the discontinuity surfaces are attached to the edges of the corners.We obtain piecewise C^(1,α) estimates across the discontinuity surfaces and provide an example to illustrate the issue regarding the regularity at the corners. 展开更多
关键词 elliptic equations divergence form discontinuous coefficients corner regularity
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Four-to Six-Year Periodic Variation of Arctic Sea-Ice Extent and Its Three Main Driving Factors
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作者 Ping CHEN Jinping ZHAO Xiaoyu WANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第10期1999-2010,共12页
Besides the rapid retreating trend of Arctic sea-ice extent(SIE),this study found the most outstanding low-frequency variation of SIE to be a 4-6-year periodic variation.Using a clustering analysis algorithm,the SIE i... Besides the rapid retreating trend of Arctic sea-ice extent(SIE),this study found the most outstanding low-frequency variation of SIE to be a 4-6-year periodic variation.Using a clustering analysis algorithm,the SIE in most ice-covered regions was clustered into two special regions:Region-1 around the Barents Sea and Region-2 around the Canadian Basin,which were located on either side of the Arctic Transpolar Drift.Clear 4-6-year periodic variation in these two regions was identified using a novel method called“running linear fitting algorithm”.The rate of temporal variation of the Arctic SIE was related to three driving factors:the regional air temperature,the sea-ice areal flux across the Arctic Transpolar Drift,and the divergence of sea-ice drift.The 4-6-year periodic variation was found to have always been present since 1979,but the SIE responded to different factors under heavy and light ice conditions divided by the year 2005.The joint contribution of the three factors to SIE variation exceeded 83%and 59%in the two regions,respectively,remarkably reflecting their dynamic mechanism.It is proven that the process of El Niño-Southern Oscillation(ENSO)is closely associated with the three factors,being the fundamental source of the 4-6-year periodic variations of Arctic SIE. 展开更多
关键词 sea-ice extent periodic variation air temperature sea-ice areal flux Arctic Transpolar Drift ice-drift divergence ENSO
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Geographical Variation in the Advertisement Calls of Leptobrachella ventripunctata(Anura:Megophryidae)in Southwestern China
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作者 Chaobo FENG Tuo SHEN +4 位作者 Lang MU Jing LIU Shize LI Yixin DIAO Haijun SU 《Asian Herpetological Research》 SCIE CSCD 2024年第3期140-151,共12页
In anurans,advertisement calls(ACs)are an essential form of intraspecific communication.This study evaluates geographical variation in the ACs of Leptobrachella ventripunctata in the Guizhou Plateau,southwestern China... In anurans,advertisement calls(ACs)are an essential form of intraspecific communication.This study evaluates geographical variation in the ACs of Leptobrachella ventripunctata in the Guizhou Plateau,southwestern China,and explores correlations between call characteristics,body size,and environmental factors.ACs are simple calls of L.ventripunctata,and apparent differences were observed in the ACs among different geographical populations of L.ventripunctata.The Call duration(CD)revealed a significant positive correlation with altitude and a significant negative correlation with temperature and humidity.Moreover,the Dominant frequency(DF)exhibited a significant negative correlation with altitude and the habitat closure degree and a significant positive correlation with temperature.These variations in ACs between different geographical populations of L.ventripunctata may critically impact the adaptive evolution of species,and the calls may also be relevant for environmental selection. 展开更多
关键词 ANURAN BIOACOUSTICS environmental factors geographical divergence
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Optimization of magnetic field design for Hall thrusters based on a genetic algorithm
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作者 谭睿 杭观荣 王平阳 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第7期82-92,共11页
Magnetic field design is essential for the operation of Hall thrusters.This study focuses on utilizing a genetic algorithm to optimize the magnetic field configuration of SPT70.A 2D hybrid PIC-DSMC and channel-wall er... Magnetic field design is essential for the operation of Hall thrusters.This study focuses on utilizing a genetic algorithm to optimize the magnetic field configuration of SPT70.A 2D hybrid PIC-DSMC and channel-wall erosion model are employed to analyze the plume divergence angle and wall erosion rate,while a Farady probe measurement and laser profilometry system are set up to verify the simulation results.The results demonstrate that the genetic algorithm contributes to reducing the divergence angle of the thruster plumes and alleviating the impact of high-energy particles on the discharge channel wall,reducing the erosion by 5.5%and 2.7%,respectively.Further analysis indicates that the change from a divergent magnetic field to a convergent magnetic field,combined with the upstream shift of the ionization region,contributes to the improving the operation of the Hall thruster. 展开更多
关键词 magnetic field design genetic algorithm divergence angle erosion of discharge channel convergent magnetic field
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Research on aiming methods for small sample size shooting tests of two-dimensional trajectory correction fuse
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作者 Chen Liang Qiang Shen +4 位作者 Zilong Deng Hongyun Li Wenyang Pu Lingyun Tian Ziyang Lin 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第3期506-517,共12页
The longitudinal dispersion of the projectile in shooting tests of two-dimensional trajectory corrections fused with fixed canards is extremely large that it sometimes exceeds the correction ability of the correction ... The longitudinal dispersion of the projectile in shooting tests of two-dimensional trajectory corrections fused with fixed canards is extremely large that it sometimes exceeds the correction ability of the correction fuse actuator.The impact point easily deviates from the target,and thus the correction result cannot be readily evaluated.However,the cost of shooting tests is considerably high to conduct many tests for data collection.To address this issue,this study proposes an aiming method for shooting tests based on small sample size.The proposed method uses the Bootstrap method to expand the test data;repeatedly iterates and corrects the position of the simulated theoretical impact points through an improved compatibility test method;and dynamically adjusts the weight of the prior distribution of simulation results based on Kullback-Leibler divergence,which to some extent avoids the real data being"submerged"by the simulation data and achieves the fusion Bayesian estimation of the dispersion center.The experimental results show that when the simulation accuracy is sufficiently high,the proposed method yields a smaller mean-square deviation in estimating the dispersion center and higher shooting accuracy than those of the three comparison methods,which is more conducive to reflecting the effect of the control algorithm and facilitating test personnel to iterate their proposed structures and algorithms.;in addition,this study provides a knowledge base for further comprehensive studies in the future. 展开更多
关键词 Two-dimensional trajectory correction fuse Small sample size test Compatibility test KL divergence Fusion bayesian estimation
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Multiple-model GLMB filter based on track-before-detect for tracking multiple maneuvering targets
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作者 CAO Chenghu ZHAO Yongbo 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第5期1109-1121,共13页
A generalized labeled multi-Bernoulli(GLMB)filter with motion mode label based on the track-before-detect(TBD)strategy for maneuvering targets in sea clutter with heavy tail,in which the transitions of the mode of tar... A generalized labeled multi-Bernoulli(GLMB)filter with motion mode label based on the track-before-detect(TBD)strategy for maneuvering targets in sea clutter with heavy tail,in which the transitions of the mode of target motions are modeled by using jump Markovian system(JMS),is presented in this paper.The close-form solution is derived for sequential Monte Carlo implementation of the GLMB filter based on the TBD model.In update,we derive a tractable GLMB density,which preserves the cardinality distribution and first-order moment of the labeled multi-target distribution of interest as well as minimizes the Kullback-Leibler divergence(KLD),to enable the next recursive cycle.The relevant simulation results prove that the proposed multiple-model GLMB-TBD(MM-GLMB-TBD)algorithm based on K-distributed clutter model can improve the detecting and tracking performance in both estimation error and robustness compared with state-of-the-art algorithms for sea clutter background.Additionally,the simulations show that the proposed MM-GLMB-TBD algorithm can accurately output the multitarget trajectories with considerably less computational complexity compared with the adapted dynamic programming based TBD(DP-TBD)algorithm.Meanwhile,the simulation results also indicate that the proposed MM-GLMB-TBD filter slightly outperforms the JMS particle filter based TBD(JMSMeMBer-TBD)filter in estimation error with the basically same computational cost.Finally,the impact of the mismatches on the clutter model and clutter parameter is investigated for the performance of the MM-GLMB-TBD filter. 展开更多
关键词 generalized labeled multi-Bernoulli(GLMB) trackbefore-detect(TBD) jump Markovian system(JMS) K-DISTRIBUTION Kullback-Leibler divergence(KLD)
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Kullback-Leibler Divergence Based ISAC Constellation and Beamforming Design in the Presence of Clutter
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作者 TANG Shuntian WANG Xinyi +1 位作者 XIA Fanghao FEI Zesong 《ZTE Communications》 2024年第3期4-12,共9页
Integrated sensing and communication(ISAC)is regarded as a pivotal technology for 6G communication.In this paper,we employ Kullback-Leibler divergence(KLD)as the unified performance metric for ISAC systems and investi... Integrated sensing and communication(ISAC)is regarded as a pivotal technology for 6G communication.In this paper,we employ Kullback-Leibler divergence(KLD)as the unified performance metric for ISAC systems and investigate constellation and beamforming design in the presence of clutters.In particular,the constellation design problem is solved via the successive convex approximation(SCA)technique,and the optimal beamforming in terms of sensing KLD is proven to be equivalent to maximizing the signal-to-interference-plus-noise ratio(SINR)of echo signals.Numerical results demonstrate the tradeoff between sensing and communication performance under different parameter setups.Additionally,the beampattern generated by the proposed algorithm achieves significant clutter suppression and higher SINR of echo signals compared with the conventional scheme. 展开更多
关键词 constellation design clutter suppression integrated sensing and communications Kullback-Leibler divergence
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调查表数据分析中变量选择和判别分析的一些方法及简单比较 被引量:5
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作者 张俊华 方伟武 《中国管理科学》 CSSCI 2000年第S1期229-236,共8页
变量选择和判别分析是调查表数据分析中的两个重要问题.文中描述了我们基于信息理论提出的四种变量选择的新方法,并把这些方法作了简单比较;同时还简要介绍了我们提出的用于判别分析的一种信息理论方法,与前人的工作相比,这里的算... 变量选择和判别分析是调查表数据分析中的两个重要问题.文中描述了我们基于信息理论提出的四种变量选择的新方法,并把这些方法作了简单比较;同时还简要介绍了我们提出的用于判别分析的一种信息理论方法,与前人的工作相比,这里的算法能用于多组样本的情况,而且计算非常简单. 展开更多
关键词 变量选择 判别分析 信息差(information divergence) 统计量
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基于模拟关系的精化检测方法 被引量:2
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作者 王婷 陈铁明 刘杨 《软件学报》 EI CSCD 北大核心 2016年第3期580-592,共13页
精化检测是一种重要的形式化验证方法,将系统实现和性质规约用相同的形式化语言进行建模,如能证明两者间存在某种精化关系,且该关系能够维持性质,可得出系统实现满足性质规约.为验证不同类型的系统性质,traces,stable failures和failure... 精化检测是一种重要的形式化验证方法,将系统实现和性质规约用相同的形式化语言进行建模,如能证明两者间存在某种精化关系,且该关系能够维持性质,可得出系统实现满足性质规约.为验证不同类型的系统性质,traces,stable failures和failures-divergence精化检测方法已被提出.精化检测算法依赖于子集构造,因而其面临状态空间爆炸问题.近年来,已有学者针对NFA语言包含问题提出了基于模拟关系的状态空间消减方法,极大地提高了算法的性能,且该方法能够直接用于traces精化检测.在此基础上,提出了基于模拟关系的stable failures和failuresdivergence精化检测方法.此外,还将精化检测扩展到了时间系统的验证中,提出了基于模拟关系的时间自动机traces精化检测方法.实验结果表明,基于模拟关系的算法效率有很大提高. 展开更多
关键词 精化检测 模拟 FAILURES DIVERGENCE 时间自动机
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UPWIND SCHEME FOR IDEAL 2-D MHD FLOWS BASED ON UNSTRUCTURED MESH 被引量:1
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作者 潘勇 王江峰 伍贻兆 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2007年第1期1-7,共7页
An upwind scheme based on the unstructured mesh is developed to solve ideal 2-D magnetohydrodynamics (MHD) equations. The inviscid fluxes are approximated by using the modified advection upstream splitting method (... An upwind scheme based on the unstructured mesh is developed to solve ideal 2-D magnetohydrodynamics (MHD) equations. The inviscid fluxes are approximated by using the modified advection upstream splitting method (AUSM) scheme, and a 5-stage explicit Runge-Kutta scheme is adopted in the time integration. To avoid the influence of the magnetic field divergence created during the simulation, the hyperbolic divergence cleaning method is introduced. The shock-capturing properties of the method are verified by solving the MHD shock-tube problem. Then the 2-D nozzle flow with the magnetic field is numerically simulated on the unstructured mesh. Computational results demonstrate the effects of the magnetic field and agree well with those from references. 展开更多
关键词 ideal magnetohydrodynamics equation unstructured mesh advection upstream splitting method(AUSM) scheme divergence cleaning
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Description of a new parthenogenetic species of Thalassaphorura (Collembola: Onychiuridae) from East China, with DNA barcoding analyses
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作者 高艳 卜云 《Entomotaxonomia》 CSCD 北大核心 2014年第1期1-7,共7页
Thalassaphorura houtanensis sp. nov. from Shanghai, East China is described. It is similar to T. encarpata (Denis, 1931) in having labial palp of type A and the same pseudocelli formula on the body. It can be distin... Thalassaphorura houtanensis sp. nov. from Shanghai, East China is described. It is similar to T. encarpata (Denis, 1931) in having labial palp of type A and the same pseudocelli formula on the body. It can be distinguished by the shape of unguis, chaetotaxy of labium, maxillary out lobe and ventral tube. It was confirmed as an absolutely parthenogenetic species after a reproduction test in the lab. In addition, the DNA barcoding sequences of this new species were sequenced and analyzed. The intraspecific genetic divergence is 0.18% on average and ranges from zero to 0.46%. 展开更多
关键词 Arthropleona SPRINGTAIL taxonomy genetic divergence REPRODUCTION
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Analysis of a Wenzhou-Hitting Exceptionally Strong Rainstorm Associated with a Typhoon Inverted Trough in September,1999
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作者 郑峰 《Marine Science Bulletin》 CAS 2010年第1期39-47,共9页
Using T106 numerical products, MM5 simulations in conjunction of Q-vector scheme-computed NCEP results, observations and satellite cloud images, study is undertaken for an exceptionally intense rainstorm event afflict... Using T106 numerical products, MM5 simulations in conjunction of Q-vector scheme-computed NCEP results, observations and satellite cloud images, study is undertaken for an exceptionally intense rainstorm event afflicting the Wenzhou region of Zhejiang province far away from the tropical storm center happening early on the morning of September 4, 1999 (TS9909 hereinafter). Evidence suggests that, like previously-studied typhoons landing in autumn south of Xiamen to the eastern part of Guangdong, TS9909 has an inverted trough in the central south of the coastal belt of Zhejiang province that produces the rainstorm from the meso convective complex (MCC) on the warm, moist shear inside; the time and order of the magnitude of the rainfall are bound up with the development of the pattern of strong Q-vector divergence gradients during the event for the study area; the NE - SW coastline and the unique topography of the Yandang mountains inside the region are favorable for air lifting are the major contributors to the torrential rains. 展开更多
关键词 long-distance-away typhoon rainstorm inverted trough MCC Q-vector divergence gradient
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The Study on the Differences of Sense of Words between English and Chinese in Translation
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作者 王雪霜 谢宇晖 《海外英语》 2014年第23期162-164,共3页
Translation is not only the process of transforming langue form, but also the process of interacting one thinking means and concept with another. Moreover, so as to ensure accuracy of translation, one needs to compreh... Translation is not only the process of transforming langue form, but also the process of interacting one thinking means and concept with another. Moreover, so as to ensure accuracy of translation, one needs to comprehend the sense of words in the source language correctly, and take appropriate approach to resolve the differences between Chinese and English through analyzing the causes. Therefore, this paper will study the differences of sense of words between English and Chinese in translation. 展开更多
关键词 eense of WORDS in CHINESE and ENGLISH DIVERGENCE t
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深度神经网络在EMD虚假分量识别中的应用 被引量:12
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作者 何定桥 王鹏军 杨军 《工程力学》 EI CSCD 北大核心 2021年第S01期195-201,共7页
无线智能传感器结合云平台可以实现建筑结构的长期健康监测,模态识别是结构健康监测的重要内容。希尔伯特黄变换(Hilbert-Huang Transform,HHT)因其适用于非线性非平稳信号,且具有完全自适应性等特点,在模态识别领域中被广泛应用。与实... 无线智能传感器结合云平台可以实现建筑结构的长期健康监测,模态识别是结构健康监测的重要内容。希尔伯特黄变换(Hilbert-Huang Transform,HHT)因其适用于非线性非平稳信号,且具有完全自适应性等特点,在模态识别领域中被广泛应用。与实验室中进行结构模态参数识别不同的是,长期监测中模态参数识别的算法不能出现主观的参数选择过程,而传统HHT的第一步经验模态分解(Empirical Mode Decomposition,EMD)会产生虚假的固有模态函数(Intrinsic Mode Function,IMF)分量,对虚假分量的识别与剔除往往依赖研究人员的主观判断。该文提出了一种基于深度神经网络(Deep Neural Networks,DNN)与K-L散度(KullbackLeibler Divergence,K-L Divergence)的新算法,可以自动化识别并剔除EMD产生的虚假分量,从而使得EMD后得到的固有模态函数均为真实分量。 展开更多
关键词 结构健康监测 自动化模态参数识别 DNN HHT EMD K-L Divergence
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通过域适应实现人脸识别 被引量:1
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作者 周军娜 陈伟 +1 位作者 王珂 汤镇宇 《计算机应用研究》 CSCD 北大核心 2017年第6期1881-1884,共4页
当源域和目的域数据分布不同时,大多数机器学习方法的性能会降低。为了解决这一问题,基于域适应的思想,提出了一种新的人脸识别方法。首先计算源域样本的相对权值,删除与目的域样本相差很大的样本,降低两域之间的差异性;然后采用基于正... 当源域和目的域数据分布不同时,大多数机器学习方法的性能会降低。为了解决这一问题,基于域适应的思想,提出了一种新的人脸识别方法。首先计算源域样本的相对权值,删除与目的域样本相差很大的样本,降低两域之间的差异性;然后采用基于正规化的Bregman divergence获得公共子空间,获得两域之间的共性;最后利用目的域样本目标化源域样本,充分利用目的域的特有信息。在此基础上建立的分类模型能够充分利用两域之间的共性和目的域的特性,实现对目的域的准确分类。为了评估方法的性能,在多个数据集上进行测试实验。实验结果证明,该方法的性能与其他几种方法相比均有所提高。 展开更多
关键词 人脸识别 域适应 相对权值 正规化的Bregman DIVERGENCE
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GENERALIZED MATRIX MULTISPLITTING RELAXATION METHODS AND THEIR CONVERGENCE 被引量:9
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作者 白中治 王德人 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 1993年第1期87-100,共14页
In this paper, we set up a general framework of parallel matrix mullisplitting relaxation methods for solving large scale system of linear equations. We investigate the convergence properties of this framework and giv... In this paper, we set up a general framework of parallel matrix mullisplitting relaxation methods for solving large scale system of linear equations. We investigate the convergence properties of this framework and give several sufficient conditions ensuring it to converge as well as diverge. At last, we conclude a necessary and sufficient condition for the convergence of this framework when the coefficient matrix is an L-matrix. 展开更多
关键词 System of linear EQUATIONS MATRIX mullisplilting RELAXATION method CONVERGENCE divergence.
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AREM Simulations of Cloud Features over Eastern China in February 2001 被引量:8
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作者 李昀英 宇如聪 +1 位作者 徐幼平 周天军 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2005年第2期260-270,共11页
Based on the simulations of cloud features in February 2001 by the regional numerical weather prediction model-Advanced Regional Eta-coordinate Model (AREM), the dynamic and thermodynamic conditions for middle cloud f... Based on the simulations of cloud features in February 2001 by the regional numerical weather prediction model-Advanced Regional Eta-coordinate Model (AREM), the dynamic and thermodynamic conditions for middle cloud formation over eastern China are studied. Diagnostic analysis partly confirms the previous suggestion that the middle stratiform clouds downstream of the Tibetaan Plateau are maintained by the frictional and blocking effects of the plateau. In addition, it is found that the temperature inversion at plateau height over eastern China generated by the warm air advected from the plateau provides a favorable thermodynamic condition for middle clouds. Both diurnal variations of the mid-level divergence and the inversion over eastern China, which are determined by the atmospheric boundary activity over the Tibetan Plateau, dominate the cloud diurnal cycle. The middle cloud amount decreases and the cloud top falls in the daytime, but reverses at night. The comparison of cloud features between the simulations and the observations also proves that the AREM can well capture the distinctive continental stratiform cloud features downstream of the Tibetan Plateau. 展开更多
关键词 AREM eastern China middle cloud DIVERGENCE INVERSION
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