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Nitrogen cycling and environmental impacts in upland agricultural soils in North China： A review

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Journal of Integrative Agriculture 2017年第12期16卷 2848-2862页

作者： ju Xiao-tang ZHANG Chong College of Resources and En vironmen tal Sciences China Agricultural University Beijing 100193 P.R. China

The upland agricultural soils in North China are distributed north of a line between the Kunlun Mountains, the Qinling Mountains and the Huaihe River. They occur in arid, semi-arid and semi-humid regions and crop production often depends on rain-fed or irrigation to supplement rainfall. This paper summarizes the characteristics of gross nitrogen（N） transformation, the fate of N fertilizer and soil N as well as the N loss pathway, and makes suggestions for proper N management in the region. The soils of the region are characterized by strong N mineralization and nitrification, and weak immobilization and denitrification ability, which lead to the production and accumulation of nitrate in the soil profile. Large amounts of accumulated nitrate have been observed in the vadose-zone in soils due to excess N fertilization in the past three decades, and this nitrate is subject to occasional leaching which leads to groundwater nitrate contamination. Under farmer＇s conventional high N fertilization practice in the winter wheat-summer maize rotation system（N application rate was approximately 600 kg ha–1 yr–1）, crop N uptake, soil residual N, NH_3 volatilization, NO_3~– leaching, and denitrification loss accounted for around 27, 30, 23, 18 and 2% of the applied fertilizer N, respectively. NH_3 volatilization and NO_3~– leaching were the most important N loss pathways while soil residual N was an important fate of N fertilizer for replenishing soil N depletion from crop production. The upland agricultural soils in North China are a large source of N_2O and total emissions in this region make up a large proportion（approximately 54%） of Chinese cropland N_2O emissions. The “non-coupled strong ammonia oxidation” process is an important mechanism of N_2O production. Slowing down ammonia oxidation after ammonium-N fertilizer or urea application and avoiding transient high soil NH4＋ concentrations are key measures for reducing N_2O emissions in this region. Further N management shou

关键词： N transformation NH3 volatilization ammonia oxidation NO3- leaching N2O emission upland agricultural soils

Weighted local polynomial estimations of a non-parametric function with censoring indicators missing at random and their applications

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Frontiers of Mathematics in China 2022年第1期17卷 117-139页

作者： Jiangfeng WANG Yangcheng ZHOU ju tang School of Statistics and Mathematics Zhejiang Gongshang UniversityHangzhou 310018China Collaborative Innovation Center of Statistical Data Engineering Technology&ApplicationZhejiang Gongshang UniversityHangzhou 310018China

In this paper,we consider the weighted local polynomial calibration estimation and imputation estimation of a non-parametric function when the data are right censored and the censoring indicators are missing at random,and establish the asymptotic normality of these *** their applications,we derive the weighted local linear calibration estimators and imputation estimations of the conditional distribution function,the conditional density function and the conditional quantile function,and investigate the asymptotic normality of these ***,the simulation studies are conducted to illustrate the finite sample performance of the estimators.

关键词： Local polynomial estimation asymptotic normality non-parametric function censoring indicator missing at random

SF_(6) decomposition behaviour under partial discharge of typical insulation defects in gas-solid insulated valve-side bushing of converter transformer

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High Voltage 2023年第4期8卷 690-697页

作者： Hongtu Cheng Fuping Zeng Bowen tang Haotian Li ju tang Zujian Huang Xianzong Chao School of Electrical Engineering and Automation Wuhan UniversityWuhanChina Hubei Key Laboratory of Power Equipment&System Security for Integrated Energy Resources WuhanChina School of Electrical and Electronic Engineering Hubei University of TechnologyWuhanChina

In this paper we investigated SF_(6) decomposition behaviour of typical insulation defects in gas-solid insulated converter transformer valve-side bushing under partial discharge(PD).Additionally,we compared the results with that of gas insulated switchgear(GIS).The results indicated that SF_(6) decomposition behaviour varies with the insulation defects *** metal protrusion defects,the proportion ranking of CO_(2) and SO_(2) can be related to whether the needle tip is wrapped with epoxy resin-impregnated paper(ERIP).The proportion of carbon-containing products is much higher under contamination defect than under other ***,the proportion of carbon-containing components is higher under flashover condition than under PD condition and is accompanied by the appearance of H2S and CS_(2).However,the yield of SO_(2)F_(2) is always *** to negative DC voltages,positive DC voltages have a higher proportion of carboncontaining components,mainly in the form of more CO_(2) and less SOF_(2).Compared to the PD decomposition behaviour of typical insulation defects in GIS,when PD involves ERIP,the proportion of carbon-containing products,especially CO_(2),is significant higher,while the proportion of sulphur containing products,especially SO_(2)F_(2),is lower.

关键词： behaviour insulation solid

Shape optimisation of basin insulator for DC gas insulated switchgear/gas insulated transmission lines based on artificial bee colony algorithm

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High Voltage 2024年第2期9卷 275-286页

作者： Yi Luo Shiyi Mao ju tang Zijun Pan Cheng Pan State Key Laboratory of Power Grid Environmental Protection School of Electrical Engineering and AutomationWuhan UniversityWuhanChina

The surface charge accumulation on the basin insulator is a particular problem in high-voltage direct current(HVDC)gas insulated switchgears(GIS)and gas insulated trans-mission lines(GIL),which restricts the development and application of extra/ultra high-voltage(EHV/UHV)*** surface charge distribution and anti-flashover performance are closely related to the insulator *** obtain the optimal basin insulator,a shape optimisation model based on artificial bee colony algorithm was established,and the minimisation objective functions based on capacitive(initial)electric field distribution and resistive(steady-state)electric field distribution were respectively *** optimisation results of the two objective functions were calculated,and the electric field and charge distribution on the surface of the insulator before and after optimisation were evaluated and compared using the simulation *** results indicated that the optimisation based on the capacitive electric field can significantly inhibit the surface charge accumulation,and the optimised insulator can significantly reduce the surface normal electric field and make the distribution of the tangential electric field more uniform,and the maximum tangential electric field can be reduced by 10%;the optimisation based on resistive electric field can achieve similar results,but requires more computational *** on the results,the‘anti-charge’basin insulator structure suitable for the DC field was given.

关键词： insulator artificial charge

Review about PD and breakdown induced by conductive particles in an insulating liquid

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High Voltage 2020年第3期5卷 287-297页

作者： Cheng Pan ju tang George Chen Yongze Zhang Xinyu Luo School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072People's Republic of China State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing UniversityChongqing 400044People's Republic of China School of Electronics and Computer Science University of SouthamptonSouthampton SO171BJUK

In insulating liquid,a conductive particle becomes charged through the interaction with a conductor exposed to an applied ***,it migrates in the action of both electric field and fluid and causes the enhancement of local field when it is in proximity of the conductor with opposite *** enhancement will lead to partial discharge(PD)and may even ignite full gap breakdown in special *** study reviews comprehensive researches relevant to these *** the first place,several theoretical methods about how to obtain the charges held by a conductive particle with known potential are introduced,so are experimental ***,forces acting on the charged particle in liquid are classified,and its migration characteristics,as well as influential factors,are ***,PD and breakdown mechanisms of liquid initiated by conductive particles are *** latter involves two cases:electric-field enhancement when the particle concentration is low and bridging phenomenon when it is *** last,two important,but frequently ignored factors,*** barrier and oil flow,are highlighted,and the authors’suggestions for future work are put forward.

关键词： field. conductive liquid

Plasma-assisted abatement of SF6 in a packed bed plasma reactor: understanding the effect of gas composition

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Plasma Science and Technology 2020年第5期22卷 95-104页

作者： Xiaoxing ZHANG Yuan TIAN Zhaolun CUI ju tang School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072People's Republic of China School of Electrical and Electronic Engineering Hubei University of TechnologyWuhan 430068People's Republic of China

The potential impact of SF6 as a potent greenhouse gas on the global climate is highly *** paper studies the effect of H2O concentration,SF6 inlet concentration and pre-heating temperature on SF6 abatement in a packed bed plasma reactor in terms of the removal efficiency and products *** results showed that the best performance in SF6 abatement was obtained at 1%H2O and 100°C with 98.7%destruction and remove efficiency(DRE)at 2%*** energy yields was obtained under higher SF6 inlet ***,the existence of water vapor weakened the micro-discharge and provided H and OH radicals for this system,which showed a close relationship to removal efficiency and products *** four sulfur-containing products,SO2 F2 was more stable than SOF2,SOF4 and ***,SOF4 and SO2 were very susceptible to the above *** article provides a better understanding of SF6 abatement in a view of both scientific and engineering.

关键词： SF6 PBR plasma gas composition

SF_(6)decomposition and insulation condition monitoring of GIE:A review

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High Voltage 2021年第6期6卷 955-966页

作者： Fuping Zeng Haotian Li Hongtu Cheng ju tang Yilu Liu School of Electrical Engineering and Automation Wuhan UniversityWuhanChina Department of Electrical Engineering and Computer Science USA Oak Ridge National Laboratory KnoxvilleTennesseeUSA

The statistics of the Conference International des Grands Reseaux Electriques(CIGRE)indicate that the operational reliability of SF6 gas‐insulated equipment(GIE)is very high;however,the failure rate of the GIE in operation is much higher than that of the IEC standard,and the fault occurs frequently in the GIE at a high voltage *** reason is due to the complex and strong on‐site electromagnetic interference environment and fully enclosed structure of *** key method and technology for effective on‐line monitoring and fault diagnosis of GIE are still *** the partial strong electromagnetic energy and high temperature induced by early latent insulation faults in the equipment,SF6 gas insulation presents different degrees of *** decomposition products mainly include SO_(2)F_(2),SOF_(2),SO_(2),HF,and *** decomposition characteristics of SF6 are closely related to the property of insulation *** present,this area is attracting attention from the power industry and research *** study summarises the current research on SF_(6)decomposition component analysis(DCA).The content mainly includes the latest progress of SF_(6)decomposition characteristics and mechanism under fault conditions,and fault diagnosis methods based on decomposition components.

关键词： insulation fault diagnosis

Reduction of N2O emissions by DMPP depends on the interactions of nitrogen sources(digestate vs. urea) with soil properties

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Journal of Integrative Agriculture 2023年第1期22卷 251-264页

作者： LI Hao-ruo SONG Xiao-tong Lars RBAKKEN ju Xiao-tang College of Resources and Environmental Sciences China Agricultural UniversityBeijing 100193P.R.China State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085P.R.China College of Tropical Crops Hainan UniversityHaikou 570228P.R.China Faculty of Chemistry Biotechnology and Food ScienceNorwegian University of Life Science(NMBU)Ås 1430Norway

The inhibition of nitrification by mixing nitrification inhibitors(NI)with fertilizers is emerging as an effective method to reduce fertilizer-induced nitrous oxide(N_(2)O)*** additive 3,4-dimethylpyrazole phosphate(DMPP)apparently inhibits ammonia oxidizing bacteria(AOB)more than ammonia oxidizing archaea(AOA),which dominate the nitrification in alkaline and acid soil,***,the efficacy of DMPP in terms of nitrogen sources interacting with soil properties remains *** therefore conducted a microcosm experiment using three typical Chinese agricultural soils with contrasting pH values(fluvo-aquic soil,black soil and red soil),which were fertilized with either digestate or urea in conjunction with a range of DMPP *** the alkaline fluvo-aquic soil,fertilization with either urea or digestate induced a peak in N_(2)O emission(60μg N kg^(-1)d^(-1))coinciding with the rapid nitrification within 3 d following *** almost eliminated this peak in N_(2)O emission,reducing it by nearly 90%,despite the fact that the nitrification rate was only reduced by 50%.In the acid black soil,only the digestate induced an N_(2)O emission that increased gradually,reaching its maximum(20μg N kg^(-1)d^(-1))after 5–7 *** nitrification rate and N_(2)O emission were both marginally reduced by DMPP in the black soil,and the N_(2)O yield(N_(2)O-N per NO2–+NO3–-N produced)was exceptionally high at 3.5%,suggesting that the digestate induced heterotrophic *** the acid red soil,the N_(2)O emission spiked in the digestate and urea treatments at 50 and 10μg N kg^(-1)d^(-1),respectively,and DMPP reduced the rates substantially by nearly 70%.Compared with 0.5%DMPP,the higher concentrations of DMPP(1.0 to 1.5%)did not exert a significantly(P<0.05)better inhibition effect on the N_(2)O emissions in these soils(either with digestate or urea).This study highlights the importance of matching the nitrogen sources,soil properties and NIs

关键词： nitrous oxide digestate urea nitrification inhibitors DMPP alkaline soils acid soils

Modulation of red-light emission from carbon quantum dots in acid-based environment and the detection of chromium(Ⅲ)ions

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Journal of Materials Science & Technology 2021年第24期83卷 58-65页

作者： ju tang Jin Zhang Weizuo Zhang Yiming Xiao Yanli Shi Fanquan Kong Wen Xu School of Physics and Astronomy and Key Laboratory of Quantum Information of Yunnan Province Yunnan UniversityKunming650091China Key Laboratory of Materials Physics Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei230031China

ⅢIn this study,the carbon quantum dots,which can emit sharp red light(R-CQDs)under optical excitation,were synthesized via simple heat treatment of wine *** features of the photoluminescence(PL)emission from R-CQDs in solutions with different p H values and with metal ions were *** intensity of the PL emission from R-CQDs depends sensitively on the p H values of the solutions with the ***,the p H-response of the PL intensity is reversible and can be enhanced linearly in the p H value range from 4 to 12,indicating that the R-CQDs can be applied for the p H ***,the quench of the PL emission from R-CQDs can be observed when adding chromium(Ⅲ)ions into the solution with *** effect can be utilized for selective and quick detection of chromium(Ⅲ)ions in solutions simply via the standard PL *** interesting and important findings from this work can be applied to explore more practical applications of the CQDs prepared cheaply and easily.

关键词： Red emitting carbon quantum dots Photoluminescence pH sensor Chromium(Ⅲ)ion detection