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Semi-automated detection of rangeland runoff and erosion control berms using high-resolution topography data

International Soil and Water Conservation Research 2024年第1期12卷 217-226页

作者： li li Changjiang River Scientific Research Institute of Changjiang Water Resources Commission Wuhan430010China Research Center on Mountain Torrent&Geologic Disaster Prevention Ministry of Water ResourcesWuhan430010China University of Arizona School of Natural Resources and the EnvironmentTucsonAZ85719USA

An inventory of topographic modifications is essential to addressing their impacts on hydrological and morphological processes in human-altered ***,such inventories are generally *** study presents two workflows for semi-automatic detection of linear earthen runoff and erosion control berms in rangelands using high-resolution topographic *** workflows consist of initial object identification by applying either morphological grayscale reconstruction(MGR)or the Geomorphon(GEO)method,followed by identification refinements through filters based on objects’horizontal and vertical *** sites were selected within the Altar Valley,Arizona,in the southwestern United *** site was used for developing workflows and optimizing filter thresholds,and the other two sites were used to validate *** results showed that:1)The MGR-based workflow methodology could produce final precision and detection rates of up to 92%and 75%,respectively,and take less than 5 s for a 10.1 km^(2) site;2)The workflow based on the MGR method yielded greater identification accuracy than did the GEO workflow;3)Object length,orientation,and eccentricity were important characteristics for identifying earthen berms,and are sensitive to general channel flow direction and berm shape;4)Manual interrogation of topographic data and imagery can significantly improve identification precision *** proposed workflows will be useful for developing inventories of runoff and erosion control structures in support of sustainable rangeland management.

关键词： Earthen berm Rangeland Grayscale morphological reconstruction Geomorphon liDAR

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Enrichment of Chemical Element ^(7)li in the Rotating Red Clump Star

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Chinese Physics Letters 2024年第8期41卷 121-125页

作者： Fang-Wen Wu Han-Feng Song Qing-li li Yun He Xin-Yue Qu Zhuo Han College of Physics Guizhou UniversityGuiyang 550025China Geneva Observatory University of GenevaCH-1290 SauvernySwitzerland

About 2 percent of red clump stars are found to be the lithium-rich and thus the surface lithium increases obviously in some red clump *** physical mechanism of the lithium enrichment in these stars has not yet been explained satisfactorily by the evolutionary models of single *** flash induced internal gravity wave mixing(i.e.,IGW)could play a primary role in explaining the red clump star with lithium enrichment and it has a very significant impact on the internal structure and surface compositions of a *** can significantly increase the mixing efficiency of the internal gravity wave because the timescale for the enrichment event has been *** mixing can explain the observed behavior of lithium on red giant stars that are more luminosity than the RGB ***,it has a very small effect on the diffusion of elements because its diffusion coefficient is much smaller than the one of IGW induced mixing after the core helium flash.

关键词： flash stars lithium

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Chemical Activation of S/li2S in li-S Batteries by a Bidirectional Organic Redox Mediator

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Chemical Research in Chinese Universities 2024年第5期40卷 927-934页

作者： li Chengqiu ZHOU Chaoyong MEI Shilin YAO Changjiang State Key Laboratory of Explosion Science and Safety Protection School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing100081P.R.China Xi’an Safty Energy Technology Co. Ltd.Xi’an710299P.R.China

The energy density and lifespan of prototype li-S batteries under high sulfur loading and lean electrolyte have been mainly restricted by the incomplete interconversion between insulating S8 and *** introduction of an electrocatalyst has been preserved as an effective way to breakthrough the bottleneck of the interconversion ***,we demonstrate a novel bidirectional redox mediator,insoluble dithiobisphthalimide(DTPI),as the electrocatalyst for both S8 reduction and li2S *** to the dual-functional role of both electron/li^(+)donor and acceptor,DTPI can efficiently accelerate the redox reactions during charge/discharge and significantly alleviate the incomplete conversion of sulfur ***,the li-S batteries with DTPI deliver superior specific capacity and cycling stability in comparison with those without ***,the redox mediator is scalable for synthesis and the DTPI-based 5 A·h pouch cell delivers a specific discharge capacity of around 870 mA·h·g^(−1) at 0.1 C(1 C=1675 mA/g)without capacity fading over 80 *** bidirectional catalysis mechanism has been studied through theoretical calculation and ex-situ characterization of the cathode *** work approves the effectiveness of bidirectional organic redox mediator in the construction of practical li-S batteries.

关键词： lithium-sulfur battery(LSB) Dithiobisphthalimide(DTPI) Organic redox mediator Interconversion

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异种化感物对落叶松八齿小蠹聚集行为的影响

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林业科学 2016年第11期52卷 107-114页

作者：李叶静孔祥波张苏芳王鸿斌张真李成喜焦相杰霍天中国林业科学研究院森林生态环境与保护研究所国家林业局森林保护学重点实验室北京100091 内蒙古自治区克什克腾旗广兴林场克什克腾025350 内蒙古自治区克什克腾旗桦木沟林场克什克腾025350

【目的】研究寄主、非寄主及近缘种的异种化感物对落叶松八齿小蠹聚集行为的影响,探讨不同信息素成分间的交互作用机制,为落叶松八齿小蠹大面积生物防治提供技术支持。【方法】从行为学的角度研究落叶松八齿小蠹对聚集信息素异构体、寄... 详细信息

【目的】研究寄主、非寄主及近缘种的异种化感物对落叶松八齿小蠹聚集行为的影响,探讨不同信息素成分间的交互作用机制,为落叶松八齿小蠹大面积生物防治提供技术支持。【方法】从行为学的角度研究落叶松八齿小蠹对聚集信息素异构体、寄主挥发物、非寄主挥发物和近缘种云杉八齿小蠹主要聚集信息素成分的行为响应差异。【结果】通过野外试验确认落叶松八齿小蠹聚集信息素成分是S-（-）-小蠹烯醇和S-（＋）-小蠹二烯醇,这2种成分复合体在林间生物测试时表现出非常高的引诱活性;电生理测试确认落叶松八齿小蠹雌雄虫触角对这2种成分的检测阈值都是0.1μg,饱和水平是100μg。进一步对具有触角电位活性的寄主、非寄主及近缘种成分进行行为测试研究。寄主单萜烯成分S-β-蒎烯和3-蒈烯对落叶松八齿小蠹聚集信息素的引诱能力增效达1.45~1.65倍,而S-α-蒎烯和萜品油烯没有显著的增效作用。非寄主成分顺-3-己烯-1-醇表现出显著的行为抑制活性,能降低聚集信息素引诱力71%,里哪醇具有与顺-3-己烯-1-醇相似的抑制效果。其他非寄主成分如桃金娘烯醇、反-3-己烯-1-醇、反-2-己烯-1-醇、正己醇、3-辛醇和1-辛烯-3-醇对落叶松八齿小蠹聚集信息素引诱效果没有显著影响。近缘种云杉八齿小蠹主要聚集信息素成分顺式马鞭草烯醇能完全抑制落叶松八齿小蠹聚集信息素的引诱活性,反式马鞭草烯醇也具有相同的作用效果,而马鞭草烯酮成分对落叶松八齿小蠹聚集信息素活性没有抑制或增效作用。【结论】具有触角电位活性的寄主和非寄主成分对落叶松八齿小蠹聚集信息素行为活性表现出增效、抑制或无显著影响;对近缘种化学信号响应表现出强烈的行为抑制效果。

关键词：落叶松八齿小蠹近缘种异种化感物聚集信息素寄主挥发物非寄主挥发物林间试验

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金昌市金川区土壤重金属累积分析及污染评价

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干旱区资源与环境 2019年第11期33卷 150-155页

作者：徐琪龚甲桂赵胜军李成习殷建伟中国冶金地质总局山东正元地质勘查院

文中按土壤利用方式将金川区分为矿业活动区、农耕区、城市活动区和未开发区,调查了金川区表层土壤中As、Hg、Cr、Ni、Cu、Zn、Cd和Pb含量及分布特征,采用相关性分析和聚类分析确定土壤重金属来源,并利用地累积指数评价了重金属污染情... 详细信息

文中按土壤利用方式将金川区分为矿业活动区、农耕区、城市活动区和未开发区,调查了金川区表层土壤中As、Hg、Cr、Ni、Cu、Zn、Cd和Pb含量及分布特征,采用相关性分析和聚类分析确定土壤重金属来源,并利用地累积指数评价了重金属污染情况。结果表明金川区土壤Hg、Cr、Ni、Cu、Cd和Pb高于甘肃省土壤背景值,Ni含量超过了国家二级标准。各分区内Ni和Cu均高于甘肃省土壤背景值。土壤中重金属主要来源于矿业活动产生的废水废气,其次为城市交通、燃煤和污水灌溉。地累积指数表明金川区Cu和Ni污染最为严重,各分区污染程度表现为:矿业活动区>农耕区>城市活动区>未开发区。

关键词：重金属含量土地利用方式重金属来源地累积指数

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Failure mechanisms and surface treatment processes of thermal barrier coatings:Review

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Chinese Journal of Aeronautics 2024年第9期37卷 20-40页

作者： Hao li Shengqiang YANG Xiuhong li Wenhui li College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024China Shan.xi Province Key Laboratory of Precise Machining Taiyuan University of TechnologyTaiyuan 030024China College of Aeronautics and Astronautics Taiyuan University of TechnologyTaiyuan 030024China

Thermal Barrier Coatings(TBCs)technology is key to improving the service temperature and the productivity of aircraft *** performance and failure life of TBCs are strongly influenced by surface integrity and ***,recognizing failure mechanisms and developing effective surface treatment processes are crucial for further improving the reliability and durability of *** paper explains the primary reasons for TBC failure,emphasizing on how integrity of surface and interface influences interfacial oxidation,high-temperature erosion,and Calcium-Magnesium-Alumina-Silicate(CMAS)***,this paper completely and rigorously evaluates the research status of TBCs surface treatment processes,including the characteristics and effects of various processes,and describes the requirements and goals of pretreatment and *** addition,a potential direction for the development and application of TBCs surface treatment is suggested.

关键词： Thermal BarrierCoatings(TBCs) Failure Surface treatment processes Processing goals Mass finishing

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Perturbed low-thrust geostationary orbit transfer guidance via polynomial costate estimation

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Chinese Journal of Aeronautics 2024年第3期37卷 181-193页

作者： Zhao li Hengnian li Fanghua JIANG Junfeng li State Key Laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

This paper proposes an optimal,robust,and efficient guidance scheme for the perturbed minimum-time low-thrust transfer toward the geostationary *** Earth’s oblateness perturbation and shadow are taken into *** is difficult for a Lyapunov-based or trajectory-tracking guidance method to possess multiple characteristics at the same time,including high guidance optimality,robustness,and onboard computational *** this work,a concise relationship between the minimum-time transfer problem with orbital averaging and its optimal solution is identified,which reveals that the five averaged initial costates that dominate the optimal thrust direction can be approximately determined by only four initial modified equinoctial orbit elements after a coordinate *** on this relationship,the optimal averaged trajectories constituting the training dataset are randomly generated around a nominal averaged *** polynomial regression models are trained on the training dataset and are regarded as the costate *** the transfer,the spacecraft can obtain the real-time approximate optimal thrust direction by combining the costate estimations provided by the estimators with the current state at any ***,all these computations onboard are *** simulation results show that the proposed guidance scheme possesses extremely high guidance optimality,robustness,and onboard computational efficiency.

关键词： Low thrust Orbital transfer Trajectory optimization Guidance Indirect method Orbital averaging Machine learning Geostationary satellites

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Theoretical Analysis of Cooperative Driving at Idealized Unsignalized Intersections

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Tsinghua Science and Technology 2024年第1期29卷 257-270页

作者： Shen li Jiawei Zhang Zhenwu Chen li li Department of Civil Engineering Tsinghua UniversityBeijing 100084China Department of Automation Tsinghua UniversityBeijing 100084China Shenzhen Urban Transport Planning Center Co. Ltd.Shenzhen 518000China

Cooperative driving is widely viewed as a promising method to better utilize limited road resources and alleviate traffic *** recent years,several cooperative driving approaches for idealized traffic scenarios(i.e.,uniform vehicle arrivals,lengths,and speeds)have been ***,theoretical analyses and comparisons of these approaches are *** this study,we propose a unified group-by-group zipper-style movement model to describe different approaches synthetically and evaluate their *** derive the maximum throughput for cooperative driving plans of idealized unsignalized intersections and discuss how to minimize the delay of *** obtained conclusions shed light on future cooperative driving studies.

关键词： cooperative driving connected and automated vehicles unsignalized intersection

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Effects of mid-passage gap with a variable surface angle on a turbine vane endwall’s aerothermal and film cooling performances

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Chinese Journal of Aeronautics 2024年第6期37卷 20-37页

作者： Zhiyu li Kaiyuan ZHANG Zhigang li Jun li Institute of Turbomachinery Xi’an Jiaotong UniversityXi’an 710049China

The mid-passage gap is an inevitable structure in a vane passage due to turbine vanes being manufactured *** coolant from this gap is able to prevent hot mainstream ingression and provide cooling protection for the endwall.A novel idea of enlarging the endwall’s coverage area and reducing the endwall’s thermal load by applying the mid-passage gap with variable surface angles is carried out in this *** endwall’s aerothermal and film cooling performances under four mid-passage gap modes at three typical mass flow ratio conditions are numerically *** indicate that under the traditional mid-passage mode,the coolant flows into the mainstream with a perpendicular incidence angle and can’t stick to the ***,cooling failure occurs,and the endwall’s thermal load is badly *** film cooling level at the suction-side endwall is improved when applying the mid-passage gap of a 45surface angle due to the secondary vortex being *** addition,when applying the mid-passage gap of a 135surface angle,the horseshoe vortex is pushed away,and the coverage area at the pressure-side endwall is enlarged *** best film cooling performance is achieved when the upstream surface angle is 135and the downstream surface angle is 45due to the adiabatic film cooling effectiveness being increased at both the pressure-and suction-side *** the mass flow ratio is 1.5%,the coverage area is enlarged by 43%,and the area-averaged adiabatic film cooling effectiveness is increased by 37%,when compared with those under the traditional mid-passage mode.

关键词： Film cooling Heat transfer Surface angle Mid-passagegap Turbinevane endwall

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秦淮河流域近30年不透水面景观格局时空演变研究

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地球信息科学学报 2017年第2期19卷 238-247页

作者：宋明明都金康郑文龙李成蹊卞国栋南京大学地理与海洋科学学院南京210023 江苏省地理信息资源开发与利用协同创新中心南京210023 江苏省地理信息技术重点实验室南京210023

不透水面作为表征城市化的重要指标,具有极其重要的生态学意义。本文选取多时相Landsat影像,以秦淮河流域为研究区,通过旋转森林算法得到9年土地利用覆盖图,并综合不透水率动态变化分析、土地利用变化轨迹分析、景观格局指数分析探究大... 详细信息

不透水面作为表征城市化的重要指标,具有极其重要的生态学意义。本文选取多时相Landsat影像,以秦淮河流域为研究区,通过旋转森林算法得到9年土地利用覆盖图,并综合不透水率动态变化分析、土地利用变化轨迹分析、景观格局指数分析探究大流域尺度在近30年间不透水面景观格局的演变过程,旨在揭示其在城市化背景下的时空演变规律。研究结果表明:近30年来,秦淮河流域城市化进程推动下的景观格局变化显著,不透水面积增长近4倍,景观优势度大幅提升;城市化格局演变在2001-2003年前后具有明显差异,前期城市扩张以南京城区与江宁区为主,后期南京城区不透水面扩张大大减缓,而溧水区与句容市扩张速度大幅提升;城市化建设后期,流域内不透水面斑块形状复杂度降低、散布与并列情况减少、斑块的连通性、聚集度逐步增加,其中连通性水平较高的地区主要集中在南京城区和江宁区。

关键词： Landsat 大流域尺度城市扩张景观格局不透水面

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