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抛荒土地不同处理及利用方式对喀斯特地区土壤微生物的影响

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农业工程学报 2013年第23期29卷 202-210页

作者：刘艳宋同清蔡德所曾馥平彭晚霞杜虎刘炀广西大学土木建筑工程学院南宁530004 中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室长沙410125 中国科学院环江喀斯特生态系统观测研究站环江547100 广西水利厅南宁530023

土壤微生物特性是土壤养分的储存库,土壤养分也影响土壤微生物活性,了解两者的相互作用机制对土地利用与管理提供理论依据,而喀斯特地区不同土地利用方式相关研究较少。基于喀斯特峰丛洼地火烧、刈割、刈割除根、封育、种植玉米、种植桂... 详细信息

土壤微生物特性是土壤养分的储存库,土壤养分也影响土壤微生物活性,了解两者的相互作用机制对土地利用与管理提供理论依据,而喀斯特地区不同土地利用方式相关研究较少。基于喀斯特峰丛洼地火烧、刈割、刈割除根、封育、种植玉米、种植桂牧1号杂交象草6种坡面典型的土地利用方式的动态监测样地建设与调查,该文分析了不同土地利用方式下土壤微生物特性,揭示其与土壤养分相互作用机制。结果表明,不同土地利用方式对土壤养分的影响不同,土壤有机质（soil organic matter,SOM）、全氮（total nitrogen,TN）、全磷（total phosphorus,TP）、碱解氮（available nitrogen,AN）等沿封育、火烧、刈割、刈割除根、种植桂牧1号、种植玉米等土地利用方式的转变而减少;不同土地利用方式土壤微生物生物量各不同,土壤微生物量碳（microbial biomass carbon,MBC）：244.98~1 246.89 mg/kg、土壤微生物量氮（microbial biomass nitrogen,MBN）：35.44~274.69 mg/kg、土壤微生物量磷（microbial biomass phosphorus,MBP）：30.88~64.72 mg/kg,其中,种植玉米土壤微生物生物量均最低,其土壤质量退化现象严重;不同土地利用方式土壤微生物种群数量及组成影响不同,种植玉米和桂牧1号杂交象草细菌占绝对优势,而火烧、刈割、刈割除根及封育均以放线菌占绝对优势,真菌的比例很少;不同土地利用方式土壤微生物特性与土壤养分之间相互作用关系不同：火烧的土壤TP和MBP、全钾（total potassium,TK）与MBC、TN与放线菌作用最强且均呈正相关,刈割的土壤TN与MBC呈正相关,刈割除根的速效磷（available phosphorus,AP）与MBN正相关,封育的pH值与MBC、真菌负相关,种植玉米的TN、TK与MBP负相关,种植桂牧1号杂交象草的pH值与真菌负相关、与放线菌正相关;聚类分析可以将喀斯特峰丛洼地6种土地利用方式划分为4类,其中封育和火烧最好。

关键词：土地利用土壤微生物土壤养分喀斯特地区

Time-Periodic Solutions to Quasilinear Hyperbolic Systems on General Networks

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 41-72页

作者： peng QU School of Mathematical Sciences Fudan UniversityShanghai 200433China

For quasilinear hyperbolic systems on general networks with time-periodic boundary-interface conditions with a dissipative structure,the existence and stability of the time-periodic classical solutions are discussed.

关键词： Time-periodic solution Quasilinear hyperbolic system General net-work Classical solution Asymptotic stability

广西环江喀斯特常绿落叶阔叶林土壤微生物类群的空间格局

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湖南农业大学学报（自然科学版） 2019年第5期45卷 507-513页

作者：宋敏彭晚霞徐庆国杜虎湖南农业大学农学院湖南长沙410128 中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室湖南长沙410125 中国科学院环江喀斯特生态系统观测研究站广西环江547100

运用地理统计学和Illumina 16S rRNA基因测序等手段,研究广西环江木论国家自然保护区25 hm2喀斯特常绿落叶阔叶林土壤主要门级微生物类群的空间分布。结果表明:广西环江木论国家自然保护区喀斯特森林土壤中优势菌门为变形菌门(Protebact... 详细信息

运用地理统计学和Illumina 16S rRNA基因测序等手段,研究广西环江木论国家自然保护区25 hm2喀斯特常绿落叶阔叶林土壤主要门级微生物类群的空间分布。结果表明:广西环江木论国家自然保护区喀斯特森林土壤中优势菌门为变形菌门(Protebacteria,34.5%)、放线菌门(Actinobacteria,30.7%)和酸杆菌门(Acidobacteria,12.2%);土壤细菌类群显示空间相关性的自相关范围为44.4~841.4 m,其中大部分细菌类群的变程在研究区域范围(500 m)内;在研究区内,变形菌门的相对丰度从北到南逐渐升高,而放线菌门和厚壁菌门(Firmicutes)的相对丰度则从北到南逐渐降低,绿弯菌门(Chloroflexi)、酸杆菌门、奇古菌门(Thaumarchaeota)、拟杆菌门(Bacteroidetes)、芽单胞菌门(Gemmatimonadetes)、疣微菌门(Verrucomicrobia)的相对丰度呈斑片状分布,硝化螺旋菌门(Nitrospirae)的相对丰度呈单峰型分布,WS3(Latescibacteria)的相对丰度则呈间歇性的低值条带和高值条带状分布。可见,喀斯特土壤主要微生物类群相对丰度呈现不同的空间分布格局。

关键词：土壤微生物群落常绿落叶阔叶林空间格局 Illumina测序喀斯特木论国家自然保护区

喀斯特峰丛洼地不同退耕还林还草模式的土壤微生物特性

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生态学报 2012年第8期32卷 2390-2399页

作者：鹿士杨彭晚霞宋同清曾馥平杜虎王克林中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室长沙410125 中国科学院环江喀斯特生态系统观测研究站环江547100 中国科学院研究生院北京100049

以坡耕地为对照,研究了喀斯特峰丛洼地任豆、香椿、板栗、柑橘、任豆+桂牧1号、桂牧1号和撂荒7种常见退耕还林还草模式下土壤微生物种群数量、微生物量碳氮磷及其分形特征和主要土壤酶活性特征。结果表明,不同退耕还林还草模式土壤微生... 详细信息

以坡耕地为对照,研究了喀斯特峰丛洼地任豆、香椿、板栗、柑橘、任豆+桂牧1号、桂牧1号和撂荒7种常见退耕还林还草模式下土壤微生物种群数量、微生物量碳氮磷及其分形特征和主要土壤酶活性特征。结果表明,不同退耕还林还草模式土壤微生物种群数量组成不同,除任豆模式外其他退耕还林还草模式均能提高土壤微生物总数量;不同退耕还林还草模式(除任豆模式外)土壤微生物量碳(MBC)含量极显著增加,撂荒地最高,土壤微生物量氮(MBN)含量变化范围不大,呈下降趋势,土壤微生物量磷(MBP)含量的变异很大,香椿、板栗、撂荒和桂牧1号模式显著或极显著高于坡耕地;土壤MBC与细菌数量的关系最相关(D=-4.07,R=0.81,P<0.01),其次为MBC与放线菌数量(D=3.82,R=0.44,P<0.05),再次为MBN与真菌数量(D=0.58,R=0.61,P<0.01),MBC与真菌数量、MBN与细菌、放线菌数量以及MBP与细菌、真菌、放线菌数量之间不存在分形关系;不同退耕还林还草模式(除桂牧1号模式外)均显著或极显著增加了土壤蔗糖酶、脲酶和磷酸酶活性。总之,不同退耕还林还草模式均改善了土壤微生物特性,为喀斯特峰丛洼地脆弱生态系统恢复与重建提供了重要依据。

关键词：退耕还林还草土壤微生物量微生物种群数量土壤酶活性喀斯特峰丛洼地

Thermal and mechanical behavior of casting copper alloy wheel during wheel and belt continuous casting process

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China Foundry 2024年第1期21卷 82-90页

作者： Kun Gao Yan peng School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina

To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting *** effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in *** each rotation,the casting wheel passes through four different spray *** results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,*** temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.

关键词： casting wheel finite element model grinding thickness casting speed hot face spray zones

Numerical simulation of fluid flow and free surface fluctuations during wheel and belt casting process

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Journal of Iron and Steel Research International 2024年第5期31卷 1117-1126页

作者： Kun Gao Yan peng National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004HebeiChina

The unstable fluid flow and severe free surface fluctuations in the wheel and belt caster can affect the quality of the cast *** lower level height tends to entrap inclusions in the molten *** the other hand,the higher level height makes the production process more dangerous due to the overflow of high temperature fluid from the mold.A computational model of the molten metal pouring process was *** transient fluid flow and free surface fluctuations behavior were calculated using the three-dimensional large eddy simulation model and the volume of fluid *** results show that the flow velocity of the main jet gradually decreases under the influence of the low kinetic energy fluid in the *** is an obvious oscillation in the tail of the jet,while the flow field is asymmetric in *** jet is closer to the inside radius side due to the Coanda effect,and there is a recirculation zone on the inside radius and the outside radius respectively,according to the 10 s time-averaged *** with the industrial observation and simulation results,the shape of the free surface is a wave that varies with *** addition,the free surface height is lowest and the flow velocity is highest in the region near the jet.

关键词： Fluid flow Free surface Wheel and belt caster Large eddy simulation Volume of fluid method

Two-Stage Online Debiased Lasso Estimation and Inference for High-Dimensional Quantile Regression with Streaming Data

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Journal of Systems Science & Complexity 2024年第3期37卷 1251-1270页

作者： peng Yanjin WANG Lei School of Statistics and Data Science KLMDASRLEBPS and LPMCNankai UniversityTianjin 300071China

In this paper,the authors propose a two-stage online debiased lasso estimation and statistical inference method for high-dimensional quantile regression(QR)models in the presence of streaming *** the first stage,the authors modify the QR score function based on kernel smoothing and obtain the online lasso smoothed QR estimator through iterative *** estimation process only involves the current data batch and specific historical summary statistics,which perfectly accommodates to the special structure of streaming *** the second stage,an online debiasing procedure is carried out to eliminate biases caused by the lasso penalty as well as the accumulative approximation error so that the asymptotic normality of the resulting estimator can be *** authors conduct extensive numerical experiments to evaluate the performance of the proposed *** experiments demonstrate the effectiveness of the proposed method and support the theoretical *** application to the Beijing PM2.5 Dataset is also presented.

关键词： Adaptive tuning asymptotic normality debiased lasso online updating quantile regres-sion

Electronic origin of structural degradation in Li-rich transition metal oxides:The case of Li_(2)MnO_(3)and Li_(2)RuO_(3)

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Journal of Semiconductors 2024年第4期45卷 82-86页

作者： peng Zhang Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics andOp toelec-tronic EngineeringShenzhen UniversityShenzhen 518060China

Li_(2)MnO_(3)and Li_(2)RuO_(3)represent two prototype Li-rich transition metal(TM)oxides as high-capacity cathodes for Li-ion batteries,which have similar crystal structures but show quite different cycling ***,based on the first-princi-ples calculations,we systematically studied the electronic structures and defect properties of these two Li-rich cathodes,in order to get more understanding on the structural degradation mechanism in Li-rich TM *** calculations indicated that the structural and cycling stability of Li_(2)MnO_(3)and Li_(2)RuO_(3)depend closely on their electronic structures,especially the energy of their highest occupied electronic states(HOS),as it largely determines the defect properties of these *** Li_(2)MnO_(3)with low-energy HOS,we found that,due to the defect charge transfer mechanism,various defects can form spontaneously in its host structure as Li ions are extracted upon delithiation,which seriously deteriorates its structural and cycling *** for Li_(2)RuO_(3),on the other hand,we identified that the high-energy HOS prevents it from the defect formation upon delithi-ation and thus preserve its cycling *** studies thus illustrated an electronic origin of the structural degradation in Li-rich TM oxides and implied that it is possible to improve their cycling performances by carefully adjusting their TM compo-nents.

关键词： defects Li-ion batteries first-principles calculations

Fourth-order phase-field modeling for brittle fracture in piezoelectric materials

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 837-856页

作者： Yu TAN Fan peng Chang LIU Daiming peng Xiangyu LI State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Science Chang'an UniversityXi'an 710064China Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Failure analyses of piezoelectric structures and devices are of engineering and scientific *** this paper,a fourth-order phase-field fracture model for piezoelectric solids is developed based on the Hamilton *** typical electric boundary conditions are involved in the present model to characterize the fracture behaviors in various physical situations.A staggered algorithm is used to simulate the crack *** polynomial splines over hierarchical T-meshes(PHT-splines)are adopted as the basis function,which owns the *** numerical simulations are performed to study the influence of the electric boundary conditions and the applied electric field on the fracture behaviors of piezoelectric *** electric boundary conditions may influence crack paths and fracture loads *** present research may be helpful for the reliability evaluation of the piezoelectric structure in the future applications.

关键词： isogeometric analysis(IGA) brittle fracture fourth-order phase-field model piezoelectric solid