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Acta Oceanologica Sinica 2024年第5期43卷 110-120页

作者： Ming Li Yuhang liu Yiyuan Sun kefeng liu College of Advanced Interdisciplinary Studies National University of Defense TechnologyNanjing 211101China Jiangsu Ocean University Lianyungang 222061China College of Horticulture Forestry Sciences Huazhong Agricultural UniversityWuhan 430070China

The mesoscale eddy(ME)has a significant influence on the convergence effect in deep-sea acoustic *** paper use statistical approaches to express quantitative relationships between the ME conditions and convergence zone(CZ)*** on the Gaussian vortex model,we construct various sound propagation scenarios under different eddy conditions,and carry out sound propagation experiments to obtain simulation *** a large number of samples,we first adopt the unified regression to set up analytic relationships between eddy conditions and CZ *** sensitivity of eddy indicators to the CZ is quantitatively ***,we adopt the machine learning(ML)algorithms to establish prediction models of CZ parameters by exploring the nonlinear relationships between multiple ME indicators and CZ *** the research,we can express the influence of ME on the CZ quantitatively,and achieve the rapid prediction of CZ parameters in ocean *** prediction accuracy(R)of the CZ distance(mean R:0.9815)is obviously better than that of the CZ width(mean R:0.8728).Among the three ML algorithms,Gradient Boosting Decision Tree has the best prediction ability(root mean square error(RMSE):0.136),followed by Random Forest(RMSE:0.441)and Extreme Learning Machine(RMSE:0.518).

关键词： convergence zone mesoscale eddy statistic analysis quantitative prediction machine learning

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二氧化碳捕集技术研究和工程示范进展

化工进展 2024年第6期43卷 2901-2914页

作者：刘克峰刘陶然蔡勇胡雪生董卫刚周华群高飞中国石油天然气股份有限公司石油化工研究院北京102206

捕集、封存(CCS)/捕集、利用和封存(CCUS)技术是缓解日趋严重气候问题的有效措施,其中CO_(2)捕集是CCS/CCUS技术中的关键环节。经过多年发展,以乙醇胺为代表以及在此基础上发展起来的多氨基胺、位阻胺、离子液体等化学胺吸收碳捕集技术... 详细信息

捕集、封存(CCS)/捕集、利用和封存(CCUS)技术是缓解日趋严重气候问题的有效措施,其中CO_(2)捕集是CCS/CCUS技术中的关键环节。经过多年发展,以乙醇胺为代表以及在此基础上发展起来的多氨基胺、位阻胺、离子液体等化学胺吸收碳捕集技术逐渐成熟,此类技术已开展或正在进行大型试验或工业示范。科研机构已经完成了技术评审(TR)的关键节点验证,积累了丰富的经验。本文结合具体案例简要介绍了包括燃烧前、富氧燃烧、化学链燃烧和燃烧后捕集技术的进展情况,分析了各类技术目前存在的主要问题,并提出了影响CO_(2)捕集技术大范围推广的关键因素。捕集能耗高、设备投资和维护成本高、产生的废弃物量大是影响捕集成本的主要因素。此外,捕集的CO_(2)主要还是用于驱油和埋存,尚不成熟的CO_(2)化工转化技术生产的产品竞争力比较弱。

关键词：二氧化碳捕集放大吸收吸附工程示范

维普期刊数据库博看期刊

Deformations of complex orbifolds and the period maps

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Science China Mathematics 2020年第1期63卷 83-100页

作者： kefeng liu Xiaobo Zhuan School of Mathematical Sciences Capital Normal UniversityBeijing 100048China Department of Mathematics University of California at Los AngelesCA 90095USA School of Science Zhejiang Sci-Tech UniversityHangzhou 310018China

We consider the deformations of complex orbifolds with the underlying smooth structures being *** a corollary,we can prove that the deformations of a Calabi-Yau orbifold is unobstructed by using standard *** we consider the period map for a family of complex Kahler *** prove that the period map is holomorphic,horizontal and consistent with our Kodaira-Spencer map.

关键词： orbifold variation of Hodge structure period map

Harmonic 2-forms and positively curved 4-manifolds

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Science China Mathematics 2021年第7期64卷 1613-1620页

作者： kefeng liu Jianming Wan Mathematical Science Research Center Chongqing University of TechnologyChongqing 400054China Department of Mathematics University of California at Los AngelesLos AngelesCA 90095USA School of Mathematics Northwest UniversityXi'an 710127China

We prove that if a compact Riemannian 4-manifold with positive sectional curvature satisfies a strengthened Kato type inequality,then it is *** also discuss some new insights for compact Riemannian 4-manifolds with po... 详细信息

关键词： positive curvature harmonic forms Hopf conjecture

Boundedness of the period maps and global Torelli theorem

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Science China Mathematics 2017年第6期60卷 1029-1046页

作者： liu kefeng SHEN Yang Center of Mathematical Sciences Zhejiang University Department of Mathematics University of California at Los Angeles

Recently, we proved the Griffiths conjecture on the boundedness of the period maps, and then used it to prove global Torelli theorem on the Torelli space under certain natural conditions. This paper serves as a review... 详细信息

关键词： moduli spaces period maps affine structures Hodge metric completion global Torelli theorem

Remarks on BCOV invariants and degenerations of Calabi-Yau manifolds

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Science China Mathematics 2019年第1期62卷 171-184页

作者： kefeng liu Wei Xia Department of Mathematics Capital Normal University Department of Mathematics University of California at Los Angeles Center of Mathematical Sciences Zhejiang University

For a one parameter family of Calabi-Yau threefolds, Green et al.(2009) expressed the total singularities in terms of the degrees of Hodge bundles and Euler number of the general fiber. In this paper,we show that the total singularities can be expressed by the sum of asymptotic values of BCOV(BershadskyCecotti-Ooguri-Vafa) invariants, studied by Fang et al.(2008). On the other hand, by using Yau's Schwarz lemma, we prove Arakelov type inequalities and Euler number bound for Calabi-Yau family over a compact Riemann surface.

关键词： BCOV invariants Calabi-Yau manifolds singularities Arakelov inequalities

A geometric heat flow for vector fields

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Science China Mathematics 2015年第4期58卷 673-688页

作者： LI Yi liu kefeng Department of Mathematics Shanghai Jiao Tong University Department of Mathematics University of California at Los AngelesLos Angeles CA 90095-1555 USA Center of Mathematical Sciences Zhejiang University

We introduce and study a geometric heat flow to find Killing vector fields on closed Riemannian manifolds with positive sectional curvature. We study its various properties, prove the global existence of the solution to this flow, discuss its convergence and possible applications, and its relation to the Navier-Stokes equations on manifolds and Kazdan-Warner-Bourguignon-Ezin identity for conformal Killing vector fields. We also provide two new criterions on the existence of Killing vector fields. A similar flow to finding holomorphic vector fields on K¨ahler manifolds will be studied by Li and liu(2014).

关键词： geometric heat flow Killing vector fields Yano's theorem Navier-Stokes equations KazdanWarner-Bourguignon-Ezin identity

Risk Assessment of Marine Environments Along the South China Sea and North Indian Ocean on the Basis of a Weighted Bayesian Network

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Journal of Ocean University of China 2021年第3期20卷 521-531页

作者： LI Ming ZHANG Ren liu kefeng College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China Collaborative Innovation Center on Meteorological Disaster Forecast Warning and AssessmentNanjing University of Information Science and EngineeringNanjing 210044China

Marine environments have a considerable influence on the construction of the Chinese 21st Century Maritime Silk ***,an objective and quantitative risk assessment of marine environments has become a key problem that must be solved *** deal with the uncertainty in marine environmental risks caused by complex factors and fuzzy mechanisms,a new assessment technique based on a weighted Bayesian network(BN)is *** risk factor analysis,node selection,structure construc-tion,and parameter learning,we apply the proposed weighted BN-based assessment model for the risk assessment and zonation of marine environments along the Maritime Silk *** show that the model effectively fuses multisource and uncertain envi-ronmental information and provides reasonable risk assessment results,thereby offering technical support for risk prevention and disaster mitigation along the Maritime Silk Road.

关键词： marine environment risk assessment Bayesian network

Adiabatic limits,vanishing theorems and the noncommutative residue

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Science China Mathematics 2009年第12期52卷 2699-2713页

作者： liu kefeng WANG Yong Center of Mathematical Sciences Zhejiang UniversityHangzhou 310027China Department of Mathematics University of California at Los AngelesLos AngelesCA 90095-1555USA School of Mathematics and Statistics Northeast Normal UniversityChangchun 130024China

In this paper,we compute the adiabatic limit of the scalar curvature and prove several vanishing theorems by taking adiabatic *** an application,we give a Kastler-Kalau-Walze type theorem for foliations.

关键词： foliations adiabatic limits vanishing theorems noncommutative residue 53C27 51H25 46L87

Evolving a Bayesian network model with information flow for time series interpolation of multiple ocean variables

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Acta Oceanologica Sinica 2021年第7期40卷 249-262页

作者： Ming Li Ren Zhang kefeng liu College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China

Based on Bayesian network (BN) and information flow (IF),a new machine learning-based model named IFBN is put forward to interpolate missing time series of multiple ocean variables. An improved BN structural learning algorithm with IF is designed to mine causal relationships among ocean variables to build network structure. Nondirectional inference mechanism of BN is applied to achieve the synchronous interpolation of multiple missing time series. With the IFBN,all ocean variables are placed in a causal network visually,making full use of information about related variables to fill missing data. More importantly,the synchronous interpolation of multiple variables can avoid model retraining when interpolative objects change. Interpolation experiments show that IFBN has even better interpolation accuracy,effectiveness and stability than existing methods.

关键词： Bayesian network information flow time series interpolation ocean variables