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An autoencoder-based model for forest disturbance detection using Landsat time series data

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International Journal of Digital Earth 2021年第9期14卷 1087-1102页

作者： Gaoxiang Zhou Ming liu xiangnan liu Department of Information and Engineering Engineering University of People’s Armed PoliceXi’anPeople’s Republic of China School of Land Engineering Chang’An UniversityXi’anPeople’s Republic of China School of Information and Engineering China University of GeosciencesBeijingPeople’s Republic of China

Monitoring and classifying disturbed forests can provide information support for not only sustainable forest management but also global carbon sequestration *** this study,we propose an autoencoder-based model for forest disturbance detection,which considers disturbances as anomalous events in forest temporal *** autoencoder network is established and trained to reconstruct intact forest ***,the disturbance detection threshold is derived by Tukey’s method based on the reconstruction error of the intact forest *** assessment result shows that the model using the NBR time series performs better than the NDVIbased model,with an overall accuracy of 90.3%.The omission and commission errors of disturbed forest are 7%and 12%,***,the trained NBR-based model is implemented in two test areas,with overall accuracies of 87.2%and 86.1%,indicating the robustness and scalability of the ***,comparing three common methods,the proposed model performs better,especially for intact forest detection *** study provides a novel and robust approach with acceptable accuracy for forest disturbance detection,enabling forest disturbance to be identified in regions with limited disturbance reference data.

关键词： Forest disturbance detection Autoencoder network Unsupervised learning Landsat time series

同域分布5种柽柳属植物不同开花时期花粉活力研究

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西北林学院学报 2025年第1期40卷 83-91页

作者：侯亚欣杨赵平刘香楠菅佳鑫曾思维塔里木大学生命科学与技术学院新疆阿拉尔843300 新疆生产建设兵团塔里木盆地生物资源保护利用兵团重点实验室新疆阿拉尔843300

为探讨柽柳属植物花粉对环境的生态适应性,以同域分布不同时期开花的短穗柽柳、长穗柽柳、甘肃柽柳、多枝柽柳和刚毛柽柳为研究对象,通过设置3个温度梯度(25、30、35℃)及2个不同硼酸浓度(5、10 mg/L)和5个蔗糖浓度(50、100、150、200、... 详细信息

为探讨柽柳属植物花粉对环境的生态适应性,以同域分布不同时期开花的短穗柽柳、长穗柽柳、甘肃柽柳、多枝柽柳和刚毛柽柳为研究对象,通过设置3个温度梯度(25、30、35℃)及2个不同硼酸浓度(5、10 mg/L)和5个蔗糖浓度(50、100、150、200、250 g/L)的交叉试验,筛选出它们的最佳培养条件。此外,还观察了这5种植物6个开花时期(花蕾期、花苞期、始花期、盛花期、凋零期和初果期)的花粉活力。结果表明:1)除夏秋季开花的多枝柽柳在35℃萌发率最高外,其余4种在30℃条件下萌发率最大。2)5种植物的最佳培养基稍有不同,短穗柽柳在10 mg/L硼酸+250 g/L蔗糖、长穗柽柳在5 mg/L硼酸+(200~250)g/L蔗糖、甘肃柽柳和刚毛柽柳在5 mg/L硼酸+150 g/L蔗糖、多枝柽柳在5 mg/L硼酸+200 g/L蔗糖条件下萌发率最高。3)5种植物的花粉活力皆在花蕾期弱,盛花期达到最高,分别为96.24%、90.04%、64.24%、46.68%和43.21%,凋零期花粉活力急剧下降。这5种同域分布的柽柳属植物花粉活力的显著差异可能与自身的遗传因素、太阳辐射和自然温度等因素有关。

关键词：柽柳属同域分布花粉培养基花粉活力生态适应性

Overview of deep space laser communication

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Science China(Information Sciences) 2018年第4期61卷 7-18页

作者： Weiren WU Ming CHEN Zhe ZHANG xiangnan liu Yuhui DONG School of Aerospace Engineering Beijing Institute of Technology Beijing Research Institute of Telemetry

The deep space probe is a vital technology for observing and exploring the universe. It is thus intensifying as an aerospace research focus on an international scale. Despite improving the frequency band,the conventional microwave communication technique has difficulty satisfying the increased demand for the enormous volume of scientific data returning to the Earth. With a carrier frequency that is several orders of magnitude higher than the microwave, free-space optical communication is a robust and promising method for achieving both high bit rates and long distances in deep space communication. In this article, the history of this technology is summarized and the objective laws are formulated, while key techniques and development trends are analyzed. Finally, useful concepts and suggestions are proposed for the development of deep space laser communication in China.

关键词： deep space communication deep space observation development process free space communication laser communication

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土地承包权退出意愿及其保障功能替代研究

中国国土资源经济 2025年第1期38卷 71-80页

作者：刘向南黄怡李淑芳南京农业大学公共管理学院江苏南京210095

从保障功能视角深入分析农户承包权退出意愿的影响因素,对于促进农地资源有效配置和提高农业生产效率具有重要意义。文章基于在山东省开展的农户调研所得到的数据,系统构建农地保障功能影响土地承包权退出意愿的理论框架,运用多元有序Lo... 详细信息

从保障功能视角深入分析农户承包权退出意愿的影响因素,对于促进农地资源有效配置和提高农业生产效率具有重要意义。文章基于在山东省开展的农户调研所得到的数据,系统构建农地保障功能影响土地承包权退出意愿的理论框架,运用多元有序Logit模型,实证分析承包地保障功能对土地承包权退出意愿的影响。研究结果表明:农户退出土地承包权的总体意愿较低,土地承包权的退出补偿机制尚不完善;个人及家庭的实际参保状况对农户退出承包权意愿的影响并不明显,但农户对社保水平的满意度具有显著的促进作用;承包地质量、经营方式、家庭经济状况、农户个人身体状况、乡土情结等因素都不同程度地影响着农户的退出决策,其中乡土情结的影响较大。基于此,文章从确定合理的补偿标准和补偿方式、完善政策支撑体系、提升养老保险和医疗保险参保率、弱化农户乡土情结等四个方面提出激励农户退出土地承包权的对策建议。

关键词：土地承包权退出意愿生计保障社会保障意愿影响因素

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中国柽柳属植物的系统发育关系和形态演化研究

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塔里木大学学报 2025年第1期37卷 19-28页

作者：李海文刘香楠杨赵平塔里木大学生命科学与技术学院新疆阿拉尔843300 塔里木盆地生物资源保护利用省部共建国家重点实验室培育基地新疆阿拉尔843300

柽柳属(Tamarix L.)隶属石竹目柽柳科(Tamaricaceae),为我国荒漠区主要类群,我国约有18种,柽柳属植物对维持荒漠区生态系统的稳定性发挥着绝对重要的作用。因种间形态差异小,仅依赖形态学对柽柳属的分类存在很大困难,早期基于分支分类... 详细信息

柽柳属(Tamarix L.)隶属石竹目柽柳科(Tamaricaceae),为我国荒漠区主要类群,我国约有18种,柽柳属植物对维持荒漠区生态系统的稳定性发挥着绝对重要的作用。因种间形态差异小,仅依赖形态学对柽柳属的分类存在很大困难,早期基于分支分类学及分子系统学研究未能很好地解决柽柳属内的支序关系。本研究选取我国柽柳属17个物种,利用多序列联合(nrITS及叶绿体ndh F-rpl32、psb A-trn H、trn Q-rps16和trn S-trn G)进行分子系统发育树推断,在此基础上选取了3个形态特征并使用Mesquite软件进行祖先性状重建分析,探讨柽柳属物种的系统发育关系和性状演化。结果表明中国柽柳属由4个分支构成:分支1为无叶柽柳支系,叶退化为鞘状抱茎;分支2为刚毛柽柳和盐地柽柳支系,幼枝被毛;分支3由白花柽柳等5个物种组成的春花组,花为4~5基数;分支4由多枝柽柳等9个物种组成,花为5基数;这4个分支与柽柳属的生物学特征基本吻合,较好地解决了该属的支序关系。

关键词：柽柳属多序列联合系统发育共衍征

Alternative Fuzzy Cluster Segmentation of Remote Sensing Images Based on Adaptive Genetic Algorithm

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Chinese Geographical Science 2009年第1期19卷 83-88页

作者： WANG Jing TANG Jilong liu Jibin REN Chunying liu xiangnan FENG Jiang Key Laboratory for Wetland Ecology and Vegetation Restoration of National Environmental Protection Northeast Normal University Changchun 130024 China Key Laboratory of Vegetation Ecology of Education Ministry Institute of Grassland Science Northeast Normal University Changehun 130024 China Changehun University of Seienee and Technology Changchun 130022 China Urban and Town Plan and Design Institute of Jilin Province Changehun 130061 China Northeast Institute of Geography and Agroecology Chinese Academy of Sciences Changchun 130012 China School of Information Engineering China University of Geosciences Beijing 100083 China

Remote sensing image segmentation is the basis of image understanding and analysis. However,the precision and the speed of segmentation can not meet the need of image analysis,due to strong uncertainty and rich texture details of remote sensing images. We proposed a new segmentation method based on Adaptive Genetic Algorithm(AGA) and Alternative Fuzzy C-Means(AFCM) . Segmentation thresholds were identified by AGA. Then the image was segmented by AFCM. The results indicate that the precision and the speed of segmentation have been greatly increased,and the accuracy of threshold selection is much higher compared with traditional Otsu and Fuzzy C-Means(FCM) segmentation methods. The segmentation results also show that multi-thresholds segmentation has been achieved by combining AGA with AFCM.

关键词： Adaptive Genetic Algorithm (AGA) Alternative Fuzzy C-Means (AFCM) image segmentation remote sensing

Ultra Dense Satellite-Enabled 6G Networks:Resource Optimization and Interference Management

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China Communications 2023年第10期20卷 262-275页

作者： xiangnan liu Haijun Zhang Min Sheng Wei Li Saba Al-Rubaye Keping Long School of Computer&Communication Engineering University of Science and Technology BeijingBeijing 100083China Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services University of Science and Technology BeijingBeijing 100083China School of Telecommunications Engineering Xidian UniversityXi’an 710071China State Radio Monitoring Center of China Beijing 100037China School of Aerospace Transport and Manufacturing Cranfield UniversityMK430ALUK

With the evolution of the sixth generation(6G)mobile communication technology,ample attention has gone to the integrated terrestrial-satellite *** paper notes that four typical application scenarios of integrated terrestrial-satellite networks are integrated into ultra dense satellite-enabled 6G networks *** the subchannel and power allocation schemes for the downlink of the ultra dense satellite-enabled 6G heterogeneous networks are *** mobile edge computing(SMEC)with edge caching in three-layer heterogeneous networks serves to reduce the link traffic of ***,a scheme for interference management is presented,involving quality-of-service(QoS)and co-tier/cross-tier interference *** simulation results show that the proposed schemes can significantly increase the total capacity of ultra dense satellite-enabled 6G heterogeneous networks.

关键词： satellite-enabled 6G networks network architecture resource optimization interference management

Ultrasmall Pt_(2)Sr alloy nanoparticles as efficient bifunctional electrocatalysts for oxygen reduction and hydrogen evolution in acidic media

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Journal of Energy Chemistry 2022年第1期31卷 315-322,I0009页

作者： xiangnan liu Shaoyun Hao Guokui Zheng Zhiwei Su Yahui Wang Qiqi Wang Lecheng Lei Yi He Xingwang Zhang Key Laboratory of Biomass Chemical Engineering of Ministry of Education College of Chemical and Biological Engineering Zhejiang UniversityHangzhou 310027ZhejiangChina Institute of Zhejiang University-Quzhou Quzhou 324000ZhejiangChina

Electrocatalytic oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER)in acidic media are vital for the applications of renewable energy ***,the low mass activity of noble Pt urgently needs to be improved due to the strong binding energetics of oxygen species(*O)with Pt *** we report fine PtxSr alloy(-2 nm)supported on N-doped carb on(NC)pyrolyzing from ZIF-8 as bifunctional electrocatalysts toward ORR and HER in acidic *** representative Pt_(2)Sr/NC exhibits an onset potential of 0.94 V *** and half-wave potential of 0.84 V toward ORR,and a low over-potential of 27 mV(10 mA cm^(-2))toward HER,***,the mass activities of Pt_(2)Sr/NC are 6.2 and 2.6 times higher than that of Pt/C toward ORR(at 0.9 V)and HER(at-30 mV),***,Pt_(2)Sr/NC possesses a retention rate of 90.97%toward acidic ORR after 35000 s of continuous *** density functional theory(DFT)calculations and X-ray photoelectron spectroscopy analysis,the incorporation of Sr into Pt forming Pt_(2)Sr alloy redistributes the electronic structures of Pt-Pt bonds,changing the rate-determining step for the ORR on Pt sites from the formation of*OH from*O to the generation of*OOH along with decreasing the energy barrier,which is also confirmed by the downshift of d band ***,the downshift of d band center also leads to the optimization of the adsorption energy(H*)with Pt,significantly improving Pt_(2)Sr/NC toward HER.

关键词： Acidic media Alloy Oxygen reduction reaction Hydrogen evolution reaction Density functional theory

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Under the Influence

China Weekly 2023年第9期 36-40页

作者： liu xiangnan 不详

Rural livestreamers are a big hit,selling local produce to help *** allis not what it *** investigates how the system works to trick sympathetic buyers into fraudulent purchases,prompting platforms to take *** the summer of 2022,recalled La Luo,who lives in Gumo Village in a remote mountainous region of Sichuan Province,strangers arrived and asked to rent four buildings.

关键词： prompt farmers Rural