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An unprotected vulnerable relict subtropical conifer-Keteleeria evelyniana: Its forests, populations, growth and endangerment by invasive alien plant species in China

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Plant Diversity 2024年第5期46卷 648-660页

作者： Cindy Q.Tang Min-Rui Du Huan-Chong Wang You-Cai shi Jia-Le Zeng Shu-Li Xiao Peng-Bin Han Jian-Ran wen shi-Qian Yao Ming-Chun Peng Chong-Yun Wang Yong-ping Li Jordi López-Pujol Institute of Ecology and Geobotany College of Ecology and Environmental ScienceYunnan UniversityBuilding#3Guozhong DalouDongwaihuan South RoadUniversity TownChenggong New DistrictKunming 650504YunnanChina College of Life Sciences Yunnan UniversityShengming Kexueyuan Building#2Chenggong CampusDongwaihuan South RoadUniversity TownChenggong New DistrictKunming 650504YunnanChina College of Natural Resources Yunnan UniversityChenggong CampusDongwaihuan South RoadUniversity TownChenggong New DistrictKunming 650504YunnanChina Botanic Institute of Barcelona(IBB CSIC-CMCNC)Passeig del Migdia s/nBarcelona 08038CataloniaSpain Escuela de Ciencias Ambientales Universidad Espíritu Santo(UEES)Samborondon 091650Ecuador

Relict subtropical coniferous forests in China face severe fragmentation,resulting in declining populations,and some are under significant threat from invasive alien *** the crucial importance of understanding forest dynamics,knowledge gaps persist,particularly regarding the impact of invasive plants on vulnerable natives like Keteleeria *** this study,we investigated the impact of invasive plants on the regeneration of forests dominated by ***,a subtropical relict species in southwestern *** this purpose,we characterized forest dynamics of 160 forest plots featuring *** as the primary dominant species and determined whether the presence of invasive plants was correlated with regeneration of *** identified four distinct forest types in which *** was *** found that radial growth of *** trees is faster in younger ageclasses today than it was for older trees at the same *** population structure of *** in each forest type exhibited a multimodal age-class ***,three forest types lacked established saplings younger than 10 years old,a situation attributed to the dense coverage of the invasive alien Ageratina *** invasive species resulted in a reduction of understory species ***,our analysis uncovered a significant negative correlation in phylogenetic relatedness(net relatedness index)between native and invasive alien plant species in eastern *** suggests closely related invasive species face heightened competition,hindering successful *** together,our findings indicate that successful establishment and habitat restoration of *** seedling/saplings require effective measures to control invasive plants.

关键词： Keteleeria evelyniana Age structure Regeneration Species diversity Invasive alien species Phylogenetic relatedness

Oilfield analogy and productivity prediction based on machine learning: Field cases in PL oilfield, China

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Petroleum Science 2024年第4期21卷 2554-2570页

作者： wen-Peng Bai shi-Qing Cheng Xin-Yang Guo Yang Wang Qiao Guo Chao-Dong Tan State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum (Beijing)

In the early time of oilfield development, insufficient production data and unclear understanding of oil production presented a challenge to reservoir engineers in devising effective development plans. To address this challenge, this study proposes a method using data mining technology to search for similar oil fields and predict well productivity. A query system of 135 analogy parameters is established based on geological and reservoir engineering research, and the weight values of these parameters are calculated using a data algorithm to establish an analogy system. The fuzzy matter-element algorithm is then used to calculate the similarity between oil fields, with fields having similarity greater than 70% identified as similar oil fields. Using similar oil fields as sample data, 8 important factors affecting well productivity are identified using the Pearson coefficient and mean decrease impurity（MDI） method. To establish productivity prediction models, linear regression（LR）, random forest regression（RF）, support vector regression（SVR）, backpropagation（BP）, extreme gradient boosting（XGBoost）, and light gradient boosting machine（Light GBM） algorithms are used. Their performance is evaluated using the coefficient of determination（R2）, explained variance score（EV）, mean squared error（MSE）, and mean absolute error（MAE） metrics. The Light GBM model is selected to predict the productivity of 30 wells in the PL field with an average error of only 6.31%, which significantly improves the accuracy of the productivity prediction and meets the application requirements in the field. Finally, a software platform integrating data query,oil field analogy, productivity prediction, and knowledge base is established to identify patterns in massive reservoir development data and provide valuable technical references for new reservoir development.

关键词： Data mining technique Analogy parameters Oilfield analogy Productivity prediction Software platform

A new two-step variational model for multiplicative noise removal with applications to texture images

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Applied Mathematics(A Journal of Chinese Universities) 2024年第3期39卷 486-501页

作者： ZHANG Long-hui YAO wen-juan shi Sheng-zhu GUO Zhi-chang ZHANG Da-zhi School of Mathematics Harbin Institute of TechnologyHarbin 150001China

Multiplicative noise removal problems have attracted much attention in recent *** additive noise,multiplicative noise destroys almost all information of the original image,especially for texture *** by the TV-Stokes model,we propose a new two-step variational model to denoise the texture images corrupted by multiplicative noise with a good geometry explanation in this *** the first step,we convert the multiplicative denoising problem into an additive one by the logarithm transform and propagate the isophote directions in the tangential field *** the isophote directions are constructed,an image is restored to fit the constructed directions in the second *** existence and uniqueness of the solution to the variational problems are *** these two steps,we use the gradient descent method and construct finite difference schemes to solve the ***,the augmented Lagrangian method and the fast Fourier transform are adopted to accelerate the *** results show that the proposed model can remove the multiplicative noise efficiently and protect the texture well.

关键词： multiplicative noise removal texture images total variation two-step variational method aug-mented Lagrangian method

Identification of reservoir types in deep carbonates based on mixedkernel machine learning using geophysical logging data

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Petroleum Science 2024年第3期21卷 1632-1648页

作者： Jin-Xiong shi Xiang-Yuan Zhao Lian-Bo Zeng Yun-Zhao Zhang Zheng-ping Zhu Shao-Qun Dong Key Laboratory of Exploration Technologies for Oil and Gas Resources of the Ministry of Education Yangtze UniversityWuhan4310HubeiChina School of Geosciences Yangtze UniversityWuhan430100HubeiChina College of Geosciences China University of Petroleum(Beijing)Beijing102249China Petroleum Exploration and Production Research Institute of SINOPEC Beijing100083China School of Earth Sciences and Engineering Xi'an Shiyou UniversityXi'an 710065ShaanxiChina

Identification of reservoir types in deep carbonates has always been a great challenge due to complex logging responses caused by the heterogeneous scale and distribution of storage *** cross-plot analysis and empirical formula methods for identifying reservoir types using geophysical logging data have high uncertainty and low efficiency,which cannot accurately reflect the nonlinear relationship between reservoir types and logging ***,the kernel Fisher discriminant analysis(KFD),a kernel-based machine learning technique,attracts attention in many fields because of its strong nonlinear processing ***,the overall performance of KFD model may be limited as a single kernel function cannot simultaneously extrapolate and interpolate well,especially for highly complex data *** address this issue,in this study,a mixed kernel Fisher discriminant analysis(MKFD)model was established and applied to identify reservoir types of the deep Sinian carbonates in central Sichuan Basin,*** MKFD model was trained and tested with 453 datasets from 7 coring wells,utilizing GR,CAL,DEN,AC,CNL and RT logs as input *** particle swarm optimization(PSO)was adopted for hyper-parameter optimization of MKFD *** evaluate the model performance,prediction results of MKFD were compared with those of basic-kernel based KFD,RF and SVM ***,the built MKFD model was applied in a blind well test,and a variable importance analysis was *** comparison and blind test results demonstrated that MKFD outperformed traditional KFD,RF and SVM in the identification of reservoir types,which provided higher accuracy and stronger *** MKFD can therefore be a reliable method for identifying reservoir types of deep carbonates.

关键词： Reservoir type identification Geophysical logging data Kernel Fisher discriminantanalysis Mixedkernel function Deep carbonates

Features and formulae of sediment incipient motion in vegetated flow environment

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Journal of Hydrodynamics 2024年第2期36卷 331-339页

作者： Yu-xuan Xu Wei-jie Wang shi-bao Zhang Han-qing Zhao Xue-kai Chen Hai-ping Zhang School of Water Conservancy North China University of Water Resources and Electric PowerZhengzhou450045China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing100038China China Three Gorges Corporation Wuhan430010China

Aquatic vegetation is a vital component of natural river ecosystems,playing a crucial role in maintaining ecological balance,providing habitat and improving water ***,the presence of vegetation results in increased resistance in vegetated channels compared with non-vegetated channels,rendering traditional sediment movement predictions inadequate for the ***,the concept of a vegetation influence factor,denoted by CDah,has been proposed by previous researchers to represent the effect of vegetation on sediment movement in *** this study,we focus on exploring the vegetation resistance coefficient(CD)among the vegetation influence factors,evaluating two different calculation methods for vegetation resistance coefficient,and presenting two expressions through genetic algorithm analysis to predict the incipient flow velocity of sediment in vegetated *** predicted values from the new formulae show excellent agreement with measured data,highlighting the high accuracy of the proposed methods in predicting the incipient flow velocity of *** results provide a solid theoretical basis for understanding the influence of aquatic vegetation on sediment particle movement.

关键词： Vegetation flow vegetation resistance coefficient genetic algorithm sediment initiation

High performance 2T0C DRAM cells based on atomic-layer-deposited InAlZnO FETs

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Science China(Information Sciences) 2024年第9期67卷 344-345页

作者： wen XIONG Binbin LUO Wei MENG Bao ZHU Xiaohan WU shi-Jin DING School of Microelectronics Fudan University

Recently, the oxide semiconductor-based 2T0C dynamic random-access memory(DRAM) has shown great potential in monolithic three-dimensional(M3D)-integrated memory,owing to some unique advantages of oxide semiconductors,such as high electron mobility, wide band gap, and compatibility with back-end-of-line(BEOL) processes [1, 2].

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Ethanol-assisted synthesis of a Ni single-atom catalyst with poriferous 3D framework for efficient cascade CO_(2)electroreduction

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Rare Metals 2024年第9期43卷 4612-4619页

作者： Feng Wu shi-Qi Wang Sebastian Kunze Xiao-ping Gao Pei-Qun Yin Yu-En Wu Division of Life Sciences and Medicine Department of EndocrinologySchool of Chemistry and Materials ScienceThe First Affiliated Hospital of USTCUniversity of Science and Technology of ChinaHefei 230026China Department of Chemistry Seoul National UniversitySeoul 08826South Korea School of Biomedical Engineering Anhui Medical UniversityHefei 230032China

The electroreduction of carbon dioxide to generate multicarbon products is significant for achieving a carbon-neutral ***,the selectivity for multi-carbon products faces several challenges,such as the intricate nature of the multistep hydrogenation processes,slow reaction kinetics and the bicarbonate precipitate issue caused by alkaline *** factors hinder the extensive utilization of this ***,we successfully developed and implemented a tandem electrolyzer cascade to separate and optimize the complex elementary reactions involved in the process of multi-carbon production.

关键词： reaction. synthesis catalyst

Approximation Algorithms for Solving the 1-Line Minimum Steiner Tree of Line Segments Problem

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Journal of the Operations Research Society of China 2024年第3期12卷 729-755页

作者： Jian-ping Li Su-Ding Liu Jun-Ran Lichen Peng-Xiang Pan wen-Cheng Wang Department of Mathematics Yunnan UniversityKunming650504YunnanChina School of Mathematics and Physics Beijing University of Chemical TechnologyBeijing650504China

We address the 1-line minimum Steiner tree of line segments(1L-MStT-LS)***,given a set S of n disjoint line segments in R^(2),we are asked to find the location of a line l and a set E_(l) of necessary line segments(i.e.,edges)such that a graph consisting of all line segments in S ∪ E_(l) plus this line l,denoted by T_(l)=(S,l,E_(l)),becomes a Steiner tree,the objective is to minimize total length of edges in E_(l) among all such Steiner ***,we are asked to find a set E_(0) of necessary edges such that a graph consisting of all line segments in S ∪ E_(0),denoted by T_(S)=(S,E_(0)),becomes a Steiner tree,the objective is to minimize total length of edges in E_(0) among all such Steiner trees,we refer to this new problem as the minimum Steiner tree of line segments(MStT-LS)*** addition,when two endpoints of each edge in Eo need to be located on two different line segments in S,respectively,we refer to that problem as the minimum spanning tree of line segments(MST-LS)*** obtain three main results:(1)Using technique of Voronoi diagram of line segments,we design an exact algorithm in time O(n log n)to solve the MST-LS problem;(2)we show that the algorithm designed in(1)is a 1.214-approximation algorithm to solve the MStT-LS problem;(3)using the combination of the algorithm designed in(1)as a subroutine for many times,a technique of finding linear facility location and a key lemma proved by techniques of computational geometry,we present a 1.214-approximation algorithm in time O(n^(3) log n)to solve the 1L-MStT-LS problem.

关键词： 1-Line minimum Steiner tree of line segments Minimum spanning tree of line segments Voronoi diagram of line segments Steiner ratio Approximation algorithms

Double casing warhead with sandwiched charge:The axial distribution of fragments velocities

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Defence Technology（防务技术） 2024年第4期34卷 201-216页

作者： ping Ye Yongxiang Dong Qitian Sun Peizhuo shi Wang Yao Yongnan Li Yujing Li Mingze Li State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The double casing warhead with sandwiched charge is a novel fragmentation warhead that can produce two groups of fragments with different velocity,and the previous work has presented a calculation formula to determine the maximum fragment *** current work builds on the published formula to further develop a formula for calculating the axial distribution characteristics of the fragment *** this type of warhead,the simulation of the dispersion characteristics of the detonation products at different positions shows that the detonation products at the ends have a much larger axial velocity than those in the middle,and the detonation products have a greater axial dispersion velocity when they are closer to the central *** loading process and the fragment velocity vary with the axial position for both casing layers,and the total velocity of the fragments is the vector sum of the radial velocity and the axial *** the same axial position,the acceleration time of the inner casing is greater than that of the outer *** the same casing,the fragments generated at the ends have a longer acceleration time than the fragments from the *** proposed formula is validated with the X-ray radiography results of the four warheads previously tested experimentally and the 3D smoothedparticle hydrodynamics numerical simulation results of several series of new warheads with different *** formula can accurately and reliably calculate the fragment velocity when the lengthto-diameter ratio of the charge is greater than 1.5 and the thickness of the casing is less than 20%its inner *** work thus provides a key reference for the theoretical analysis and the design of warheads with multiple casings.

关键词： Double casing warhead Sandwiched charge Fragment velocity Rarefaction wave Gurney formula Explosive loading