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Estimating vertical vegetation density through a SPOT5 imagery at multiple radiometric correction levels

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Forestry Studies in China 2012年第1期14卷 55-62页

作者： gu zhu-jun LIU Jia-xue School of Bio-Chemical and Environmental Engineering Nanjing Xiaozhuang University Nanjing 211171 P. R. China

There is growing concern about remote sensing of vertical vegetation density in rapidly expanding peri-urban interfaces. A widely used parameter for such density, i.e., leaf area index （LAI）, was measured in situ in Nanjing, China and then correlated with two vegetation indices （VI） derived from multiple radiometric correction levels of a SPOT5 imagery. The VIs were a normal- ized difference vegetation index （NDVI） and a ratio vegetation index （RVI）, while the four radiometric correction levels were i） post atmospheric correction reflectance （PAC）, ii） top of atmosphere reflectance （TOA）, iii） satellite radiance （SR） and iv） digital number （DN）. A total of 157 LAI-VI relationship models were established. The results showed that LA! is positively correlated with VI （r varies from 0.303 to 0.927, p 〈 0.001）. The R： values of＂pure＂ vegetation were generally higher than those of mixed vegetation. The average R2 values of about 40 models based on DN data （0.688） were higher than that of the routinely used PAC （0.648）. Independent variables of the optimal models for different vegetation quadrats included two vegetation indices at three radiometric correction lev- els, indicating the potential of vegetation indices at multiple radiometric correction levels in LAI inversion. The study demonstrates that taking heterogeneities of vegetation structures and uncertainties of radiometric corrections into account may help full mining of valuable information from remote sensing images, thus improving accuracies of LAI estimation.

关键词： radiometric correction vegetation index (VI) leaf area index (LAI) model

Analyzing Forest Effects on Runoff and Sediment Production Using Leaf Area Index

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Journal of Mountain Science 2014年第1期11卷 119-130页

作者： WU Xiao-Xia gu zhu-jun LUO Hao SHI Xue-Zheng YU Dong-Sheng School of Bio-Chemical and Environmental Engineering Nanjing Xiaozhuang University Institute of Hydro-geophysical Prospecting Chongqing Research Institute of China Coal Technology & Engineering Group Corporation State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of Sciences

Quantifying the effects of forests on water and soil conservation helps further understanding of ecological functions and improving vegetation reconstruction in water-eroded *** on the effects of vegetation on water and soil conservation have generally focused on vegetation types or vegetation horizontal distribution ***,only a few studies have used indicators that consider the vegetation vertical *** study used the leaf area index(LAI) to investigate the relationship between forests and water and soil conservation in experimental *** 2007 to 2010,rainfall characteristics,LAI,and water and soil loss in 144 natural erosive rainfall events were measured from five pure tree plots(Pinus massoniana).These tree plots were located in Hetian Town,Changting County,Fujian Province,which is a typical water-eroded area in Southern *** polynomial regression models for LAI and water/soil conservation effects(RE/SE) were established for each *** RE and SE corresponded to the ratios of the runoff depth(RD) and the soil loss(SL) of each pure tree plot to those of the control plot under each rainfall *** transformation LAIs of the LAI–RE and LAI–SE curves,as well as the rainfall characteristics for the different water/soil conservation effects,were *** increasing LAI resulted in descending,descending–ascending,ascending–descending,and ascending trends in the LAI–RE and LAI–SE *** rainfall frequencies corresponding to each trend of LAI–RE and LAI–SE were different,and the rainfall distributions were not uniform per *** effects of soil conservation in the plots were superior to those of water *** of the RE and SE values presented a positive effect on water and soil *** main factor that caused different effects was rainfall *** heavy rains(e.g.,rainfall erosivity R = 145 MJ mm/ha h and maximum 30 min intensity I30 = 13 mm/h),the main effects were positive,wher

关键词： Water loss Soil erosion Pinus massoniana Soil conservation Transformation LAI

Multifunctional AlPO_(4)reconstructed LiMn_(2)O_(4)surface for electrochemical lithium extraction from brine

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Journal of Energy Chemistry 2024年第2期89卷 410-421,I0010页

作者： jun gu Linlin Chen Xiaowei Li guiling Luo Linjing Fan Yanhong Chao Haiyan Ji Wenshuai zhu School of Materials Science and Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina School of Chemistry and Chemical Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina College of Science State Key Laboratory of Heavy Oil ProcessingChina University of Petroleum-BeijingBeijing 102249China School of the Environment and Safety Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina

LiMn_(2)O_(4)(LMO)electrochemical lithium-ion pump has gained widespread attention due to its green,high efficiency,and low energy consumption in selectively extracting lithium from ***,collapse of crystal structure and loss of lithium extraction capacity caused by Mn dissolution loss limits its industrialized ***,a multifunctional coating was developed by depositing amorphous AlPO_(4)on the surface of LMO using sol-gel *** characterization and electrochemical performance test provided insights into the mechanism of Li^(+)embedment and de-embedment and revealed that multifunctional AlPO_(4)can reconstruct the physical and chemical state of LMO surface to improve the interface hydrophilicity,promote the transport of Li^(+),strengthen cycle ***,after 20 cycles,the capacity retention rate of 0.5AP-LMO reached 93.6%with only 0.147%Mn dissolution *** average Li^(+)release capacity of 0.5AP-LMO//Ag system in simulated brine is 28.77 mg/(g h),which is 90.4%higher than ***,even in the more complex Zabuye real brine,0.5AP-LMO//Ag can still maintain excellent lithium extraction *** results indicate that the 0.5AP-LMO//Ag lithium-ion pump shows promising potential as a Li^(+)selective extraction system.

关键词： LiMn_(2)O_(4) Multifunctional AlPO_(4)coating Li^(+)embedment and de-embedment mechanism Stability Hydrophilicity Various solution

Volume of fluid simulation of single argon bubble dynamics in liquid steel under RH vacuum conditions

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Journal of Iron and Steel Research International 2024年第4期31卷 828-837页

作者： gu-jun Chen Sheng-ping He College of Materials Science and Engineering Yangtze Normal UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

Single argon bubble dynamics in liquid steel under Ruhrstahl-Heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer and pressure *** simulation with a constant bubble density was also performed to validate the numerical method,and the predicted terminal bubble shape and velocity were found to agree with those presented in the Grace diagram and calculated by drag correlation,*** simulation results under RH conditions indicate that the terminal bubble shape and velocity cannot be *** primary bubble growth occurs within a rising distance of 0.3 m owing to heating by the high-temperature liquid steel;subsequently,the bubble continues to grow under equilibrium with the hydrostatic *** the initial diameter is 8-32 mm,the bubble diameter and rising velocity near the liquid surface are 80-200 mm and 0.5-0.8 m/s,*** bubble rises rectilinearly with an axisymmetric shape,and the shape evolution history includes an initial sphere,(dimpled)ellipsoid,and spherical cap with satellite bubbles.

关键词： Bubble dynamics Liquid steel Volume of fluid Bubble growth Bubble shape Rising velocity

Prediction of liquid circulation flow rate in RH degasser:improvement of decarburization at low atmospheric pressure

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Journal of Iron and Steel Research International 2024年第7期31卷 1661-1667页

The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-Heraeus(RH)*** predicted circulation flow rate was compared with that measured from a water model experiment to validate the mathematical ***,influence of snorkel immersion depth on liquid circulation flow rate was numerically investigated under an atmospheric pressure of 101 and 84 kPa,*** result indicates that the circulation flow rate of the RH degasser in the high-altitude area was severely reduced because of the decrease in atmospheric ***,increasing the snorkel immersion depth from 0.5 to 0.7 m can compensate for the decrease in atmospheric *** test result indicates that decarburization rate is significantly enhanced by increasing the snorkel immersion *** optimization,the percentage of heats with a final carbon content less than 0.002 wt.%is significantly increased from 22.0%to 96.4%.

关键词： RH degasser Two-fluid model Population balance model-Circulation flow rate Decarburization Snorkel immersion depth

A Model for Estimating Total Forest Coverage with Ground-Based Digital Photography

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Pedosphere 2010年第3期20卷 318-325页

作者： gu zhu-jun ZENG Zhi-Yuan SHI Xue-Zheng LI Lin D. C. WEINDORF ZHA Yong YU Dong-Sheng LIU YongoMei State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of SciencesNanjing 210008 (China) School of Bio-Chemical and Environmental Engineering Nanjing Xiaozhuang University Nanjing 211171 (China) College of Geography Science Nanjing Normal University Nanjing 210097 (China) Department of Earth Sciences Indiana University-Purdue University Indianapolis IN 46202 (USA) LSU AgCenter Baton Rouge LA 70803 (USA)

Vegetation fractional coverage (VFC) is one of the key indicators of vegetation distribution. In the work a measurement-based model was developed to derive total forest VFC (TG) as well as the VFC of trees (T) and shrub-grasses (G) separately in a subtropical forest area in Nanjing, China. Both upward and downward photographs were taken with a digital camera in 72 quadrats (10 m × 10 m each). Fifteen models were established and validated. Models jointly using both T and G performed better than those using the T and G separately. The best model, TG = T + G- 1.134 × T × G- 0.025 (R2 = 0.9115, P < 0.01, root mean squared error = 0.0789), is recommended for application. This model provides a good way to obtain total forest VFC values through taking tree and shrub-grass photos on ground below tree canopy rather than above tree canopy.

关键词： digital camera 2-layer photography shrub-grasses trees

Impact of atmospheric circulations on droughts and drought propagation over China

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Science China Earth Sciences 2024年第8期67卷 2633-2648页

作者： Ziye gu Lei gu Jiabo YIN Wei FANG Lihua XIONG jun guO Ziyue ZENG jun XIA School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Water Resources Engineering and Management Wuhan 430072China Changjiang River Scientific Research Institute Wuhan 430010China

The GRACE satellite mission provides a new approach for monitoring,tracking,and assessing drought conditions by detecting changes in Earth's gravitational fields and inversing signals of terrestrial water storage *** studies of terrestrial water storage anomalies related droughts paid rare attention to the behind atmospheric physical mechanisms,nor quantified the risk propagation patterns between terrestrial water storage deficits and hydrological or agricultural *** this study,we first extract terrestrial water storage(TWS) droughts,hydrological droughts,and agricultural droughts by using multiple variables including TWS from the GRACE/GRACE-FO satellites,runoff and soil moisture from the ERA5-Land reanalysis *** then identify key atmospheric and oceanic oscillation indices affecting water deficits by employing machine learning *** characterize the joint distributions between drought duration and severity by using the Copula function and quantify the risk propagation of hydrological and agricultural droughts to TWS *** results show that:(1) From 2002 to 2021,there is a significant decrasing trend of TWS in China;the WPIO group atmospheric circulation indices(sea surface temperature index within the Western Pacific and Indian Ocean) contributes the most to ***,the sea surface temperature anomalies within the NINO 3.4 region as well as the Western Pacific Warm Pool area index show significantly positive correlation relationships with TWS in southern China;(2) The northwestern China,the Yangtze River basin,and the downstream of the Pearl River basin are the hotspots of TWS ***,the hotspots of hydrological droughts locate in northwestern China and the hotspots of agricultural droughts locate in South China and eastern Tibetan Plateau;(3) The elastic coefficients of hydrological droughts propagating to TWS droughts are higher than those of agricultural droughts,indicating that the TWS droughts

关键词： GRACE satellites Drought Drought propagation Atmospheric circulation Copula function

A bibliometric analysis of molybdenum-based nanomaterials in the biomedical field

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Tungsten 2024年第1期6卷 17-47页

作者： Zhi-Qiang Wang Ya-Wen Pan Jing Wu Hong-Bin Qi Shuang zhu Zhan-jun gu School of Science China University of GeosciencesBeijing 100083China CAS Key Laboratory for Biomedical Eff ects of Nanomaterials and Nanosafety Institute of High Energy PhysicsBeijing 100049China CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology of ChinaChinese Academy of SciencesBeijing 100190China College of Materials Science and Optoelectronic Technology University of Chinese Academy of SciencesBeijing 100049China

Molybdenum(Mo)-based nanomaterials have been widely used in biomedical fields due to their various nanostructures and unique physical/chemical *** various reviews have described the development of Mo-based materials in the biomedical field,an objective and comprehensive summary and analysis of research trends in this field is still ***,we used the bibliometric analysis method to analyze all relevant literature on the biological application of Mobased nanomaterials in recent ***,we use bibliometric tools to analyze the dataset by year,country/region,institution and research hotspot to obtain the research ***,based on objectively identified research hotspots,the biomedical applications of Mo-based nanomaterials are reviewed comprehensively,mainly including sensors,cancer imaging/therapy and antibacterial ***,we discussed the application prospects and challenges of Mo-based *** article provides a new perspective to understand the current research progress and further promote the development of Mobased nanomaterials in biomedical research.

关键词： Molybdenum Nanomaterial Biomedicine Bibliometric analysis

An Image Fingerprint and Attention Mechanism Based Load Estimation Algorithm for Electric Power System

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 577-591页

作者： Qing zhu Linlin gu Huijie Lin Electricity Technology Branch Nari Technology Co.Ltd.Nanjing211106China NARI-TECH Nanjing Control Systems Co. Ltd.Nanjing211106China

With the rapid development of electric power systems,load estimation plays an important role in system operation and ***,load estimation techniques contain traditional,time series,regression analysis-based,and machine learning-based *** the machine learning-based method can lead to better performance,in this paper,a deep learning-based load estimation algorithm using image fingerprint and attention mechanism is ***,an image fingerprint construction is proposed for training *** the data preprocessing,the training data matrix is constructed by the cyclic shift and cubic spline ***,the linear mapping and the gray-color transformation method are proposed to form the color image ***,a convolutional neural network(CNN)combined with an attentionmechanism is proposed for training performance *** last,an experiment is carried out to evaluate the estimation *** with the support vector machine method,CNN method and long short-term memory method,the proposed algorithm has the best load estimation performance.

关键词： Load estimation deep learning attention mechanism image fingerprint construction