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Soil Phosphorus Composition and Phosphatase Activities along Altitudes of Alpine Tundra in Changbai Mountains,China

Chinese Geographical Science 2016年第1期26卷 90-98页

作者： YANG Xiaozhu WEI Kai chen Zhenhua chen lijun State Key Laboratory of Forest and Soil Ecology Institute of Applied EcologyChinese Academy of SciencesShenyang 110164China University of Chinese Academy of Sciences Beijing 100049China

Alpine tundra ecosystems have specific vegetation and environmental conditions that may affect soil phosphorus （P） composition and phosphatase activities. However, these effects are poody understood. This study used NaOH-EDTA extraction and solution ^31P nuclear magnetic resonance （NMR） spectroscopy to determine soil P composition and phosphatase activities, including acid phosphomonoesterase （AcP）, phosphodiesterase （PD） and inorganic pyrophosphatase （IPP）, in the alpine tundra of the Changbai Mountains at seven different altitudinal gradients （i.e., 2000 m, 2100 m, 2200 m, 2300 m, 2400 m, 2500 m, and 2600 m）. The results show that total P （TP）, organic P （OP）, OP/TP, NaOH-EDTA extracted P and AcP, PD, and IPP activities over the altitude range of 2500-2600 m are significantly lower than those below 2400 m. The dominant extracted form of P is OP （73%0-83%） with a large proportion of monoesters （65%0-72%）, whereas inorganic P is present in lower proportions （17%-27%）. The activity of AcP is significantly positively correlated with the contents of soil OP, total carbon （TC）, total nitrogen （TN）, and TP （P 〈 0.05）, indicating that the AcP is a more sensitive index for responding P nutrient storage than PD and IPP. Soil properties, P composition, and phosphatase activities decrease with increased altitude and soil pH. Our results indicate that the distribution of soil P composition and phosphatase activities along altitude and AcP may play an important role in P hydrolysis as well as have the potential to be an indicator of soil quality.

关键词： alpine tundra ecosystem altitude phosphatase activity phosphorus (P) composition solution ^31p nuclear magnetic resonance (NMR) spectroscopy

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Global cultivated land mapping at 30 m spatial resolution

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Science China Earth Sciences 2016年第12期59卷 2275-2284页

作者： CAO Xin chen XueHong ZHANG WeiWei LIAO AnPing chen lijun chen ZhiGang chen Jin State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University National Geomatics Center of China College of Geomatics Anhui University of Science and Technology

Cultivated land is one of the most important types of land cover in the global mapping of land cover, and its variation influences economic development, food security, and ecological environment protection. Existing products of global cultivated land mapping have a low resolution, and high spatial resolution products are in demand. This study uses global remote sensing image datasets in 2000/2010 with a spatial resolution of 30 m(Landsat TM/ETM+, HJ-1), MODIS 250 m NDVI time-serial data, and many types of reference data. An three-layer extraction method based on pixels, objects, and knowledge(POK) was adopted to ease cultivated land extraction in global-scale 30 m images, i.e., cultivated land classification based on pixel-scale multi-feature optimization, cultivated land automatic identification based on objects, and interactive object processing based on information service and priori knowledge. Global 30 m cultivated land mapping was accomplished for the two reference years(2000 and 2010), and statistical analysis was conducted on the data. Results showed that the total cultivated land area was 1.903 billion ha and 1.960 billion ha, respectively. Accuracy assessments showed that overall accuracy of global cultivated land mapping are higher than 92% for both the two reference years. The global cultivated land products in 2000/2010 developed in this research are superior to their international counterparts in terms of spatial resolution and classification accuracy. They also provide significant basic data on global food security, ecological environment supervision, and global change.

关键词： Cultivated land global 30 m resolution Remote sensing mapping NDVI time series

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Properties of Polyacrylate Latex Prepared Under Different Emulsified Systems

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Journal of Wuhan University of Technology(Materials Science) 2012年第1期27卷 134-137页

作者： chen lijun WU Fengqin School of Chemical Engineering and Materials Science Zhejiang University of TechnologyHangzhou 310032China Intertek Testing Services Hangzhou 310052China

The polyacrylate latexes were synthesized via pre-emulsified and semi-continuous seeded emulsion polymerization technology when conventional surfactant or polymerizable surfactant was used as emulsifiers. The resultant latexes and their films were characterized with the contact angle determinator and rheometer. Effect of the polymerizable surfactant on water resistance, stability and rheology of the latex was studied. Results show that the water resistance of film is increased first then decreased with the increase of the amount of the polymerizable surfactant. There exists the optimum value of the amount of the polymerizable surfactant for the water resistance of the film. In comparison with the latex prepared with the conventional surfactant, both the mechanical stability and the freezing-thaw stability of the latex are improved when the polymerizable surfactant is used during the course of the emulsion polymerization. The resultant latex has rheological properties of pseudo-plastic fluid and belongs to non-Newtonian fluid.

关键词： polymerizable emulsifier HPMAS polyacrylate latex binder properties

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Influence of climate warming and nitrogen deposition on soil phosphorus composition and phosphorus availability in a temperate grassland,China

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Journal of Arid Land 2014年第2期6卷 156-163页

作者： GuangNa ZHANG ZhenHua chen AiMing ZHANG lijun chen ZhiJie WU State Key Laboratory of Forest and Soil Ecology Institute of Applied EcologyChinese Academy of Sciences University of Chinese Academy of Sciences Shandong Provincial Key Laboratory of Water and Soil Conservation & Environmental Protection Linyi University Institute of Applied Ecology Chinese Academy of Sciences

Climate warming and nitrogen （N） deposition change ecosystem processes, structure, and functioning whereas the phosphorus （P） composition and availability directly influence the ecosystem structure under condi- tions of N deposition. In our study, four treatments were designed, including a control, diurnal warming （DW）, N deposition （ND）, and combined warming and N deposition （WN）. The effects of DW, ND, and WN on P composition were studied by 3~p nuclear magnetic resonance （3~p NMR） spectroscopy in a temperate grassland region of China. The results showed that the N deposition decreased the soil pH and total N （TN） concentration but increased the soil OIsen-P concentration. The solution-state 31p NMR analysis showed that the DW, ND and WN treatments slightly decreased the proportion of orthophosphate and increased that of the monoesters. An absence of myo-inositol phosphate in the DW, ND and WN treatments was observed compared with the control. Furthermore, the DW, ND and WN treatments significantly decreased the recovery of soil P in the NaOH-EDTA solution by 17%-20%. The principal component analysis found that the soil pH was positively correlated with the P recovery in the NaOH-EDTA solution. Therefore, the decreased soil P recovery in the DW and ND treatments might be caused by an indirect influence on the soil pH. Additionally, the soil moisture content was the key factor limiting the available P. The positive correlation of total carbon （TC） and TN with the soil P composition indicated the influence of climate warming and N deposition on the biological processes in the soil P cycling.

关键词： climate warming nitrogen deposition temperate grassland 31p nuclear magnetic resonance spectroscopy

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Predicting the potential distribution of invasive exotic species using GIS and information-theoretic approaches:A case of ragweed(Ambrosia artemisiifolia L.)distribution in China

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Chinese Science Bulletin 2007年第9期52卷 1223-1230页

作者： chen Hao chen lijun Thomas P. ALBRIGHT School of Remote Sensing Information Engineering Wuhan University Wuhan 430079 China National Geomatics Center of China Beijing 100080 China SAIC USGS Center for EROS Sioux Falls SD 57198 USA Department of Zoology University of Wisconsin-Madison WI USA

Invasive exotic species pose a growing threat to the economy,public health,and ecological integrity of nations worldwide. Explaining and predicting the spatial distribution of invasive exotic species is of great importance to prevention and early warning efforts. We are investigating the potential distribution of invasive exotic species,the environmental factors that influence these distributions,and the ability to predict them using statistical and information-theoretic approaches. For some species,detailed presence/absence occurrence data are available,allowing the use of a variety of standard statistical techniques. However,for most species,absence data are not available. Presented with the challenge of developing a model based on presence-only information,we developed an improved logistic regres-sion approach using Information Theory and Frequency Statistics to produce a relative suitability map. This paper generated a variety of distributions of ragweed(Ambrosia artemisiifolia L.) from logistic regression models applied to herbarium specimen location data and a suite of GIS layers including climatic,topographic,and land cover information. Our logistic regression model was based on Akaike's Information Criterion(AIC) from a suite of ecologically reasonable predictor variables. Based on the results we provided a new Frequency Statistical method to compartmentalize habitat-suitability in the native range. Finally,we used the model and the compartmentalized criterion developed in native ranges to “project” a potential distribution onto the exotic ranges to build habitat-suitability maps.

关键词：外来入侵物种潜在分布预测信息论 GIS 豚草属

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Optimized Design of Spacer in Electrodialyzer Using CFD Simulation Method

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Journal of Ocean University of China 2018年第3期17卷 603-608页

作者： JIA Yuxiang YAN Chunsheng chen lijun HU Yangdong Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education College of Chemistry and Chemical Engineering Ocean University of China

In this study, the effects of length-width ratio and diversion trench of the spacer on the fluid flow behavior in an electrodialyzer have been investigated through CFD simulation method. The relevant information, including the pressure drop, velocity vector distribution and shear stress distribution, demonstrates the importance of optimized design of the spacer in an electrodialysis process. The results show width of the diversion trench has a great effect on the fluid flow compared with length. Increase of the diversion trench width could strength the fluid flow, but also increase the pressure drop. Secondly, the dead zone of the fluid flow decreases with increase of length-width ratio of the spacer, but the pressure drop increases with the increase of length-width ratio of the spacer. So the appropriate length-width ratio of the space should be moderate.

关键词： computational fluid dynamics electrodialysis fluid flow spacer

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A Prediction-Based Multi-Objective VM Consolidation Approach for Cloud Data Centers

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Computers, Materials & Continua 2024年第7期80卷 1601-1631页

作者： Xialin Liu Junsheng Wu lijun chen Jiyuan Hu School of Computer Science Northwestern Polytechnical UniversityXi’an710005China School of Computer Science and Technology Xi’an University of Posts and TelecommunicationsXi’an710021China Shaanxi Key Laboratory of Network Data Analysis and Intelligent Processing Xi’an University of Posts and TelecommunicationsXi’an710021China School of Software and Microelectronics Northwestern Polytechnical UniversityXi’an710005China School of Automation Xi’an University of Posts and TelecommunicationsXi’an710021China

Virtual machine(VM)consolidation aims to run VMs on the least number of physical machines(PMs).The optimal consolidation significantly reduces energy consumption(EC),quality of service(QoS)in applications,and resource *** paper proposes a prediction-basedmulti-objective VMconsolidation approach to search for the best mapping between VMs and PMs with good timeliness and practical *** use a hybrid model based on Auto-Regressive Integrated Moving Average(ARIMA)and Support Vector Regression(SVR)(HPAS)as a prediction model and consolidate VMs to PMs based on prediction results by HPAS,aiming at minimizing the total EC,performance degradation(PD),migration cost(MC)and resource wastage(RW)*** results usingMicrosoft Azure trace show the proposed approach has better prediction accuracy and overcomes the multi-objective consolidation approach without prediction(i.e.,Non-dominated sorting genetic algorithm 2,Nsga2)and the renowned Overload Host Detection(OHD)approaches without prediction,such as Linear Regression(LR),Median Absolute Deviation(MAD)and Inter-Quartile Range(IQR).

关键词： VM consolidation prediction multi-objective optimization machine learning

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Preparation of ternary Mg-Li-Sn alloys from molten salt by electrolysis

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Acta Metallurgica Sinica(English Letters) 2012年第4期25卷 265-271页

作者： Peng CAO Milin ZHANG Wei HAN Yongde YAN lijun chen Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of MaterialsScience and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China

Electrochemical behavior of Mg, Li and Sn on tungsten electrodes in LiC1-KC1-MgCI2- SnC12 melts at 873 K was investigated. Cyclic voltammograms （CVs） showed that the underpotential deposition （UPD） of magnesium on pre-deposited tin leads to the formation of a Mg-Sn alloy, and the succeeding underpotential deposition of lithium on pre-deposited Mg-Sn alloy leads to the formation of a Mg-Li-Sn alloy. Chronopo- tentiometric measurements indicated that the codepositon of Mg, Li and Sn occurs at current densities more negative than -1.16 ***-~. X-ray diffraction （XRD） in- dicated that Mg2Sn phase is formed via galvanostatic electrolysis. The element Mg distributes homogeneously and Sn locates mainly on the grain boundaries in the Mg- Li-Sn alloy.

关键词： Mg-Li-Sn alloy Molten salt Cyclic voltammetry Electrolysis

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Common Best Proximity Points Theorems

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Journal of Mathematical Research with Applications 2019年第3期39卷 289-294页

作者： lijun chen Jin Shan College Fujian Agriculture and Forestry University

In this paper, an existence and uniqueness common best proximity point theorem for a pair of non-self mappings was proved. Moreover, an example is given to support our main result, which generalized some well-known re... 详细信息

关键词： common best proximity point generally proximally dominating mappings common fixed points

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A landscape shape index-based sampling approach for land cover accuracy assessment

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Science China Earth Sciences 2016年第12期59卷 2263-2274页

作者： chen Fei chen Jun WU Hao HOU DongYang ZHANG WeiWei ZHANG Jun ZHOU XiaoGuang chen lijun School of Geosciences and Info-Physics Central South University National Geomatics Center of China

Spatial sampling design is one of the key steps in land cover accuracy assessment,and many traditional sampling approaches may not achieve credible spatial sampling due to the high spatial heterogeneity of land *** paper characterizes the spatial heterogeneity with three-level LSIs and determines the subsequent sample sizes and their spatial *** three-level LSIs are rLSI in a region,cLSI for each land cover class and uLSI in each geographic sampling unit in the *** rLSIs are used to derive appropriate sample sizes in the target *** cLSIs are used to assure that larger sample numbers are allocated to land cover classes with higher spatial *** uLSIs provide useful measures for selecting optimal geographic units in which sample sites will be *** LSI-based sampling approach can derive the sample sizes and determine their distributions in an adaptive way according to the spatial *** experimental case study further demonstrates that the LSI-based sampling approach obtains more appropriate sample sizes for each region,sufficient sample numbers for rare classes,and optimal sample distributions in the geographical space.

关键词： Land cover Sampling Landscape index Spatial heterogeneity Accuracy assessment

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