Identifying plant water sources is fundamental for elucidating ecohydrological processes and improving water resource management in arid zones under climate change.Stable hydrogen and oxygen isotopes are commonly used...Identifying plant water sources is fundamental for elucidating ecohydrological processes and improving water resource management in arid zones under climate change.Stable hydrogen and oxygen isotopes are commonly used to trace plant water uptake;however,cryogenic vacuum extraction(CVE),the standard method for extracting plant xylem water,may induce deuterium depletion,thereby biasing source attribution.To systematically assess the effects of CVE-induced deuterium depletion across species,size classes,and habitats,we excavated five representative soil profiles along the mainstream of the Tarim River in northwestern China,in mid-July 2022.A total of 29 individuals,comprising both Populus euphratica and Tamarix ramosissima,were sampled.We divided P.euphratica individuals into four groups based on diameter at breast height(<50,50-100,100-250,and>250 cm),while categorized T.ramosissima individuals into four groups according to plant height(<1.0,1.0-2.0,2.0-4.0,and>4.0 m).Plant xylem water was extracted using CVE,and five deuterium depletion scenarios(-5.00‰,-7.00‰,-9.00‰,-11.00‰,and-13.00‰)were simulated.The Bayesian Mixing Model for Stable Isotope Analysis in R(MixSIAR)was applied under six input modes to quantify the proportional contributions of potential water sources and associated prediction errors.Model evaluation revealed that P.euphratica achieved the highest accuracy with a-9.00‰correction of depletion,whereas a-11.00‰ correction was optimal for T.ramosissima,reducing relative prediction errors by 68.65%and 67.73%,respectively,compared with uncorrected scenario.Small-sized P.euphratica individuals exhibited less deuterium depletion,whereas no clear size-dependent pattern was observed for T.ramosissima.Spatially,plant individuals located farther from the river exhibited reduced deuterium depletion in xylem water.Despite differences in species traits and habitat conditions,both species predominantly relied on deep soil water and groundwater,which together contributed,on average,61.45%and 59.95%for P.euphratica and T.ramosissima,respectively.These findings highlight the necessity of accounting for CVE-induced deuterium depletion when identifying plant water-use strategies and provide methodological guidance for isotope-based ecohydrological studies in arid environments.展开更多
Accurately estimating depth from underwater monocular images is essential for the target tracking task of unmanned underwater vehicles.This work proposes a method based on the Lpg-Lap Unet architecture.First,the Unet ...Accurately estimating depth from underwater monocular images is essential for the target tracking task of unmanned underwater vehicles.This work proposes a method based on the Lpg-Lap Unet architecture.First,the Unet architecture integrates Laplacian pyramid depth residuals and Sobel operators to improve the boundary details in depth images,which may suffer from the feature loss caused by upsampling and the blurriness of underwater images.Multiscale local planar guidance layers then fully exploit the intermediate depth features,and a comprehensive loss function ensures robustness and accuracy.Experimental results on benchmarks demonstrate the effectiveness of Lpg-Lap Unet and its superior performance over state-of-the-art models.An underwater target tracking system is then designed to further validate its real-time capabilities in the AirSim simulation platform.展开更多
静止变频器(static frequency converter,SFC)在运输行业、电力行业、工业自动化、新能源行业应用广泛,已成为现代工业生产中重要的一环。然而,SFC驱动电机易引发电能质量问题,以抽水蓄能电站为例,SFC起动产生的谐波导致厂用电设备损坏...静止变频器(static frequency converter,SFC)在运输行业、电力行业、工业自动化、新能源行业应用广泛,已成为现代工业生产中重要的一环。然而,SFC驱动电机易引发电能质量问题,以抽水蓄能电站为例,SFC起动产生的谐波导致厂用电设备损坏或自动装置误动作,甚至谐波传递至上级电网,影响电网的安全稳定运行。针对SFC起动过程中的谐波问题,研究非特征谐波产生机理,建立考虑限流电抗器的SFC网侧电流精准数学模型,分析得出影响非特征谐波含量的主要因素,揭示断续换相过程、电机内部扰动和外部扰动过程对非特征谐波的普适性影响规律。最后,基于某抽水蓄能电站的实际参数搭建Matlab/Simulink仿真模型,结合现场测试结果,验证所提方法对抽水蓄能电站内部非特征谐波特性分析的正确性与准确性。展开更多
基金supported by the National Key R&D Program of China(2023YFC3206801)the National Natural Science Foundation of China(42171041).
文摘Identifying plant water sources is fundamental for elucidating ecohydrological processes and improving water resource management in arid zones under climate change.Stable hydrogen and oxygen isotopes are commonly used to trace plant water uptake;however,cryogenic vacuum extraction(CVE),the standard method for extracting plant xylem water,may induce deuterium depletion,thereby biasing source attribution.To systematically assess the effects of CVE-induced deuterium depletion across species,size classes,and habitats,we excavated five representative soil profiles along the mainstream of the Tarim River in northwestern China,in mid-July 2022.A total of 29 individuals,comprising both Populus euphratica and Tamarix ramosissima,were sampled.We divided P.euphratica individuals into four groups based on diameter at breast height(<50,50-100,100-250,and>250 cm),while categorized T.ramosissima individuals into four groups according to plant height(<1.0,1.0-2.0,2.0-4.0,and>4.0 m).Plant xylem water was extracted using CVE,and five deuterium depletion scenarios(-5.00‰,-7.00‰,-9.00‰,-11.00‰,and-13.00‰)were simulated.The Bayesian Mixing Model for Stable Isotope Analysis in R(MixSIAR)was applied under six input modes to quantify the proportional contributions of potential water sources and associated prediction errors.Model evaluation revealed that P.euphratica achieved the highest accuracy with a-9.00‰correction of depletion,whereas a-11.00‰ correction was optimal for T.ramosissima,reducing relative prediction errors by 68.65%and 67.73%,respectively,compared with uncorrected scenario.Small-sized P.euphratica individuals exhibited less deuterium depletion,whereas no clear size-dependent pattern was observed for T.ramosissima.Spatially,plant individuals located farther from the river exhibited reduced deuterium depletion in xylem water.Despite differences in species traits and habitat conditions,both species predominantly relied on deep soil water and groundwater,which together contributed,on average,61.45%and 59.95%for P.euphratica and T.ramosissima,respectively.These findings highlight the necessity of accounting for CVE-induced deuterium depletion when identifying plant water-use strategies and provide methodological guidance for isotope-based ecohydrological studies in arid environments.
基金partially supported by the Natural Science Foundation of Shandong Province,China(No.ZR2023ME009)the National Natural Science Foundation of China(No.51909252)。
文摘Accurately estimating depth from underwater monocular images is essential for the target tracking task of unmanned underwater vehicles.This work proposes a method based on the Lpg-Lap Unet architecture.First,the Unet architecture integrates Laplacian pyramid depth residuals and Sobel operators to improve the boundary details in depth images,which may suffer from the feature loss caused by upsampling and the blurriness of underwater images.Multiscale local planar guidance layers then fully exploit the intermediate depth features,and a comprehensive loss function ensures robustness and accuracy.Experimental results on benchmarks demonstrate the effectiveness of Lpg-Lap Unet and its superior performance over state-of-the-art models.An underwater target tracking system is then designed to further validate its real-time capabilities in the AirSim simulation platform.
文摘静止变频器(static frequency converter,SFC)在运输行业、电力行业、工业自动化、新能源行业应用广泛,已成为现代工业生产中重要的一环。然而,SFC驱动电机易引发电能质量问题,以抽水蓄能电站为例,SFC起动产生的谐波导致厂用电设备损坏或自动装置误动作,甚至谐波传递至上级电网,影响电网的安全稳定运行。针对SFC起动过程中的谐波问题,研究非特征谐波产生机理,建立考虑限流电抗器的SFC网侧电流精准数学模型,分析得出影响非特征谐波含量的主要因素,揭示断续换相过程、电机内部扰动和外部扰动过程对非特征谐波的普适性影响规律。最后,基于某抽水蓄能电站的实际参数搭建Matlab/Simulink仿真模型,结合现场测试结果,验证所提方法对抽水蓄能电站内部非特征谐波特性分析的正确性与准确性。
