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| 1 | Unimodal productivity-biodiversity relationship along the gradient of multidimensional resources across Chinese grasslands显示文摘Resources can affect plant productivity and biodiversity simultaneously and thus are key drivers of their relationships in addition to plant-plant interactions.However,most previous studies only focused on a single resource while negle cting the nature of resource multidimensionality.Here we integrated four essential resources for plant growth into a single metric of resource diversity(RD)to investigate its effects on the productivity-biodiversity relationship(PBR)across Chinese grasslands.Results showed that habitats differing in RD have different PBRs—positive in low-resource habitats,but neutral in medium-and high-resource ones—while collectively,a weak positive PBR was observe d.However,when excluding direct effects of RD on productivity and biodiversity,the PBR in high-resource habitats became negative,which leads to a unimodal instead of a positive PBR along the RD gradient.By integrating resource effects and changing plant-plant interactions into a unified framework with the RD gradient,our work contributes to uncovering underlying me chanisms for inconsistent PBRs at large scales. | Yanfen Wang Jianqing Du Zhe Pang Yali Liu Kai Xue Yann Hautier Biao Zhang Li Tang Lili Jiang Baoming Ji Xingliang Xu Jing Zhang Ronghai Hu Shutong Zhou Fang Wang Rongxiao Che Di Wang Chaoting Zhou Xiaoyong Cui Nico Eisenhauer Yanbin Hao | 2022 | National Science Review2022，9，12： | 2 |
| 2 | Cloth simulation-based construction of pitfree canopy height models from airborne LiDAR data显示文摘Background:The universal occurrence of randomly distributed dark holes(i.e.,data pits appearing within the tree crown)in LiDAR-derived canopy height models(CHMs)negatively affects the accuracy of extracted forest inventory parameters.Methods:We develop an algorithm based on cloth simulation for constructing a pit-free CHM.Results:The proposed algorithm effectively fills data pits of various sizes whilst preserving canopy details.Our pitfree CHMs derived from point clouds at different proportions of data pits are remarkably better than those constructed using other algorithms,as evidenced by the lowest average root mean square error(0.4981 m)between the reference CHMs and the constructed pit-free CHMs.Moreover,our pit-free CHMs show the best performance overall in terms of maximum tree height estimation(average bias=0.9674 m).Conclusion:The proposed algorithm can be adopted when working with different quality LiDAR data and shows high potential in forestry applications. | Wuming Zhang Shangshu Cai Xinlian Liang Jie Shao Ronghai Hu Sisi Yu Guangjian Yan | 2020 | Forest Ecosystems2020，7，1： | 1 |
| 3 | STUDY ON TORSIONAL VIBRATION PROBLEM OF MINE HOST GEAR-TRANSMISSION SYSTEM显示文摘STUDYONTORSIONALVIBRATIONPROBLEMOFMINEHOSTGEARTRANSMISSIONSYSTEM①LiangZhaozhengHuZongwuSunXiaomingSchoolofMechanicalEngineri... | Liang Zhaozheng Hu Zongwu Sun Xiaoming School of Mechanical Engineering, Shanghai Jiaotong University Meng Huirong Xia Ronghai China University of Mining and Technology | 1998 | Chinese Journal of Mechanical Engineering1998，11，3： | 0 |
| 4 | Quantitative Evaluation of Leaf Inclination Angle Distribution on Leaf Area Index Retrieval of Coniferous Canopies显示文摘Both leaf inclination angle distribution(LAD)and leaf area index(LAI)dominate optical remote sensing signals.The G-function,which is a function of LAD and remote sensing geometry,is often set to 0.5 in the LAI retrieval of coniferous canopies even though this assumption is only valid for spherical LAD.Large uncertainties are thus introduced.However,because numerous tiny leaves grow on conifers,it is nearly impossible to quantitatively evaluate such uncertainties in LAI retrieval.In this study,we proposed a method to characterize the possible change of G-function of coniferous canopies as well as its effect on LAI retrieval.Specifically,a Multi-Directional Imager(MDI)was developed to capture stereo images of the branches,and the needles were reconstructed.The accuracy of the inclination angles calculated from the reconstructed needles was high.Moreover,we analyzed whether a spherical distribution is a valid assumption for coniferous canopies by calculating the possible range of the G-function from the measured LADs of branches of Larch and Spruce and the true G-functions of other species from some existing inventory data and threedimensional(3D)tree models.Results show that the constant G assumption introduces large errors in LAI retrieval,which could be as large as 53%in the zenithal viewing direction used by spaceborne LiDAR.As a result,accurate LAD estimation is recommended.In the absence of such data,our results show that a viewing zenith angle between 45 and 65 degrees is a good choice,at which the errors of LAI retrieval caused by the spherical assumption will be less than 10%for coniferous canopies. | Guangjian Yan Hailan Jiang Jinghui Luo Xihan Mu Fan Li Jianbo Qi Ronghai Hu Donghui Xie Guoqing Zhou | 2021 | Journal of Remote Sensing2021，，1： | 0 |
| 5 | Integrated visual navigation based on angles-onlymeasurements for asteroid final landing phase显示文摘Visual navigation is imperative for successful asteroid exploration missions.In this study,an integrated visual navigation system was proposed based on angles-only measurements to robustly and accurately determine the pose of the lander during the final landing phase.The system used the lander's global pose information provided by an orbiter,which was deployed in space in advance,and its relative motion information in adjacent images to jointly estimate its optimal state.First,the landmarks on the asteroid surface and markers on the lander were identified from the images acquired by the orbiter.Subsequently,an angles-only measurement model concerning the landmarks and markers was constructed to estimate the orbiter's position and lander's pose.Subsequently,a method based on the epipolar constraint was proposed to estimate the lander's inter-frame motion.Then,the absolute pose and relative motion of the lander were fused using an extended Kalman filter.Additionally,the observability criterion and covariance of the state error were provided.Finally,synthetic image sequences were generated to validate the proposed navigation system,and numerical results demonstrated its advance in terms of robustness and accuracy. | Ronghai Hu Xiangyu Huang Chao Xu | 2023 | Astrodynamics2023，7，1： | 0 |
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