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Scale Effects of Geographical Soil Datasets on Soil Carbon Estimation in Louisiana,USA:A Comparison of STATSGO and SSURGO

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Pedosphere 2011年第4期21卷 491-501页

作者： B. ZHONG Y. j. xu School of Renewable Natural Resources Louisiana State University Agricultural Center Baton Rouge LA 70803 (USA)

Estimation of soil organic carbon （SOC） pools and fluxes bears large uncertainties because SOC stocks vary greatly over geographical space and through time. Although development of the U.S. Soil Survey Geographic Database （SSURGO）, currently the most detailed level with a map scale ranging from 1：12 000 to 1：63 360, has involved substantial government funds and coordinated network efforts, very few studies have utilized it for soil carbon assessment at the large landscape scale. The obj.ctives of this study were to 1） compare estimates in soil organic matter among SSURGO, the State Soil Geographic Database （STATSGO）, and referenced field measurements at the soil map unit; 2） examine the influence of missing data on SOC estimation by SSURGO and STATSGO; 3） quantify spatial differences in SOC estimation between SSURGO and STATSCO, specifically for the state of Louisiana; and 4） assess scale effects on soil organic carbon density （SOCD） estimates from a soil map unit to a watershed and a river basin scale. SOC was estimated using soil attributes of SSURGO and STATSGO including soil organic matter （SOM） content, soil layer depth, and bulk density. Paired t-test, correlation, and regression analyses were performed to investigate various relations of SOC and SOM among the datasets. There were positive relations of SOC estimates between SSURGO and STATSGO at the soil map unit （R2 = 0.56, n = 86, t = 1.65, P = 0.102; depth： 30 cm）. However, the SOC estimated by STATSGO were 9%, 33% and 36~ lower for the upper 30-cm, the upper l-m, and the maximal depth （up to 2.75 m） soils, respectively, than those from SSURGO. The difference tended to increase as the spatial scale changes from the soil map unit to the watershed and river basin scales. Compared with the referenced field measurements, the estimates in SOM by SSURGO showed a closer match than those of STATSCO, indicating that the former was more accurate than the latter in SOC estimation, both in spatial and temporal resoluti

关键词： carbon accounting climate change GIS soil organic carbon soil organic matter

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A new insight into electrochemical detection of eugenol by hierarchical sheaf-like mesoporous NiCo2O4

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Nano Research 2015年第8期8卷 2636-2645页

作者： Mylamparambil Udayan Anu Prathap Chao Wei Shengnan Sun Zhichuan j. xu School of Materials Science and Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore

NiCo2O4 nanosheets with sheaf-like nanostructure morphologies have been synthesized by a facile one-step hydrothermal reaction followed by annealing treatment. Impressively, the NiCo2O4 nanosheets exhibit rapid detection of eugenol. The linear range of detection is from 1-500μM, and the limit of detection is 5.4 μM. The NiCo2O4 modified electrode demonstrated high sensitivity, good repeatability and reproducibility, and long-term stability （7% decrease in response over 30 days）. Based on this work, an electrochemical reaction mechanism for eugenol oxidation was proposed, and in addition, the NiCo2O4 modified electrode was successfully employed for the analysis of eugenol in medicative balm samples. Recovery values for eugenol in medicative balm samples were in the range 98.7%-105.5%.

关键词： NiCo2O4 nanosheets eugenol determination electrocatalysis electrochemical mechanism real sample analysis

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SUPERPLASTICITY OF A SiC_w/2024 Al COMPOSITE MADE BY PRESSURE INFILTRATION

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Acta Metallurgica Sinica(English Letters) 2002年第5期15卷 425-430页

作者： X. j. xu , W. Wang and L. Caij.angsuUniversity of Science and Technology, Zhenj.ang 212013, China j.angsu Univ. of Sci. and Technol. Zhenjiang 212013 China

The superplastic characteristics of the β-SiC whisker reinforced 2024 aluminum composite, fabricated by pressure infiltration and hot-rolling after extrusion, were investigated. The composite has a fine grain size of about 1μm, and exhibits a maximum tensile elongation of 370% in the initial strain rate of 3.3×10-3 s-1 at *** superplastic deformation mechanism of the composite is thought to be grain boundary (interface) sliding accommodated by grain boundary diffusion of aluminum atom and an appropriate amount of liquid phase.

关键词： superplasticity aluminum matrix composites pressure infiltra-tion

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A Method of Inversing the Peak Density of Atomic Oxygen Vertical Distribution in the MLT Region From the OI (557.7 nm)Night Airglow Intensity

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空间科学学报 2005年第5期25卷 484-489页

作者： H. Gao j. Y. xu W. Yuan Laboratory for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China China-Russia j.int Research Center on Space Weather Graduate School Chinese Academy of Sciences Beijing 100039

In this paper, using the MSISE-90 model as the reference atmosphere, we discuss the feasibility and method of deducing the peak densities of the undisturbed atomic oxygen profiles in the MLT region (the mesosphere and lower thermosphere region) from OI (557.7 nm) night airglow intersities. The peak densities for different seasons, latitudes and longitudes are deduced from OI (557.7nm) airglow intensities through this expression. We analyze the features of inversion relative errors and discuss the influence of the variations in temperature on inversion errors. The results indicate that all inversion errors are less than 5% except for those at high altitudes in the summer hemisphere. And the impact of the variations in temperature on errors is not significant.

关键词：原子氧 MLT 气辉天文

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Araucaria cunninghamii Seedling Response to Different Forms and Rates of ^(15)N-Labelled Fertiliser

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Pedosphere 2006年第6期16卷 745-755页

作者： T, j. BLUMFIELD xu Zhi-Hong Centre for Forestry and Horticultural Research Nathan Campus Griffith University 170 Kessels Road Nathan Queens- land 4111 （Australia） Faculty of Environmental Sciences Griffith University Nathan Campus Griffith University 170 Kessels Road Nathan Queensland 4111 （Australia）

Nitrogenous fertilisers are under consideration for promoting the growth of nursery-reared hoop pine （Araucaria cunninghamii Alton ex A. Cunn） seedlings in the establishment phase of second rotation （2R） plantations. Using ^15N- labelled fertilisers, we investigated the effect of different forms （ammonium sulphate, ammonium nitrate, potassium nitrate and urea） and rates of application （0, 150 and 300 mg N kg^-1 dried soil） of fertilisers on the growth, ^15N recovery and carbon isotope composition （δ^13C） of hoop pine seedlings in a 12-month glasshouse trial in southeast Queensland, Australia. The ^15N-labelled fertilisers were applied to nursery-reared hoop pine seedlings, which were then grown in pots, containing ca. 1.2 kg dried soil, under well watered conditions for 12 months. Four seedlings from each treatment were harvested at 4-month intervals, divided into roots, stem and foliage, with a further subdivision for new and old foliage, and then analysed for ^15N, total N, δ^13C and total C. There was no significant response in the seedling growth to the form or rate of application of nitrogen （N） fertiliser within the 12-month period, indicating that the seedlings did not experience N deficiency when grown on second rotation hoop pine soils. While the combined ^15N recovery from soil and plant remained at around 70% throughout the experiment, the proportion of ^15N recovered from the plants increasing steadily over time. Nitrate containing fertilisers at 150 mg N kg^-1 soil gradually increased seedling foliage δ^13C over the 12-month period, indicating an increase in seedling water use efficiency.

关键词： hoop pine ^15N recovery nitrogen water use efficiency

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FE SIMULATION OF CENTER CRACK OCCURRENCE IN TUBE ROUNDS DURING TWO-ROLL ROTARY ROLLING PROCESS

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Acta Metallurgica Sinica(English Letters) 2007年第3期20卷 225-234页

作者： S.Z. Li j. xu Y.D. Yin j.G. xue F. Pan j.M. Zheng j.H. Yoon Department of Materials Forming and Control Engineering Anhui University of Technology Ma＇anshan 243002 China Provincial Key Laboratory of Metals and Processing Ma＇anshan 243002 China Steel Tube ＆ Pipe Company of Bao Steel Co. Ltd. Shanghai 200941 China Department of Metallurgy and Materials Science Changwon National University Changwon 641-773 Korea

With the aid of FE （finite element） code *** 2005, 2-D coupled thermo-mechanical simulation of center-crack occurrence in round billet during 2-roll rotary rolling process was presented using Oyane ductile fracture criteria. A simple modeling is put forward based on the spiral motion of the workpiece as an essential characteristic in movement. The influence of the feed angle and the entry cone angle of the main roll on the process was taken into account in the modeling. The soundness for simplifying the 3-D rotary rolling into a 2-D problem was discussed. By adopting the parameters of Diescher piercer in 140mm mandrel mill of Bao Steel, the distribution and development of strain/stress were analyzed, and the eigen value of ductile fracture as well. The critical percentage of diameter reduction was obtained from the simulation. The result showed a good agreement with the experimental value, and therefore was of widely guiding significance to the practical process for rationally formulating the deformation parameters of steel tube piercing.

关键词： numerical simulation inside crack, tube piercing rotary rolling seamless tube deformation

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The Nonlinear Model of the Response of Airglow to Gravity Waves

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空间科学学报 2005年第5期25卷 490-494,F0003页

作者： j. Y. xu H. Gao A. V. Mikhalev Laboratory for Space Weather Center for Space Science and Applied Research Chinee Academy of Sciences Beijing 100080 China Institute of Solar-Terrestrial Physics Siberian Branch Russian Academy of Sciences Irkutsk 664033 Russia China-Russia j.int Research Center on Space Weather

In this paper, we develope a timodependent, nonlinear, photochemical-dynamical 2-D model which is composed of 3 models: dynamical gravity wave model, middle atmospheric photochemical model, and airglow layer photochemical model. We use the model to study the effect of the gravity wave propagation on the airglow layer. The comparison between the effects of the different wavelength gravity wave on the airglow emission distributions is made. When the vertical wavelength of the gravity wave is close to or is shorter than the thickness of the airglow layer, the gravity wave can make complex structure of the airglow layer, such as the double and multi-peak structures of the airglow layer. However, the gravity wave that has long vertical wavelength can make large scale perturbation of the airglow emission distribution.

关键词：重力波气辉天文非线性模型

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AGE STRENGTHENING OF DIFFUSION WELDED j.INT OF Al_2O_(3p)/6061Al COMPOSITE

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Acta Metallurgica Sinica(English Letters) 2000年第1期13卷 18-22页

作者： j. T. Niu Y. H. Tian B. Y. Li j. j. xu L.M. Liu (National Key Laboratory of Advanced welding Production Technology, HIT, Harbin 150001, China)

Tensile strength of diffusion welded j.int of aluminum matrix composite is very low due to its poor weld- *** this paper, solution and age treatments were conducted on the welded j.int of Al2O3p/ 6061Al composite subj.cted to diffusion welding using Gleeble 1500 machine, and ensile strength and microstructure of welded j.int aged at175℃ were measured and analyzed respectively, Results showed that aging precipitation of welded j.int is promoted effectively because of redistribution of reinforcement and a few number of dislocations in the matrix of weld zone resulting from welding pressure,and hence tensile strength of welded j.int is increased significantly after aging treatment.

关键词： aluminum matrix composite diffusion welding aging

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Aerodynamic load control on a dynamically pitching wind turbine airfoil using leading-edge protuberance method

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Acta Mechanica Sinica 2020年第2期36卷 275-289页

作者： Y.N.Zhang M.M.Zhang C.Cai j.Z.xu Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China The Key Laboratory of Wind Energy Utilization of CAS Beijing 100190China University of Chinese Academy of Sciences Beijing 100049China Dalian National Laboratory for Clean Energy Chinese Academy of SciencesDalian 116023China

The aerodynamic loads of wind turbine blades are substantially affected by dynamic stall induced by the variations of the angle of attack of local airfoil *** purpose of the present study is to explore the effect of leading-edge protuberances on the fluctuation of the aerodynamic performances for wind turbine airfoil during dynamic *** experimental investigation is carried out by a direct force measurement technique employing force balance at a Reynolds number Re=2×*** phase-averaged and instantaneous aerodynamic loads of the pitching airfoil,including the baseline and the wavy airfoil,are presented and *** phase-averaged results indicate that the effects of dynamic stall for the wavy airfoil can be delayed or minimized compared to the baseline airfoil,and the negative damping area of the wavy airfoil is significant decreased in full-stall *** effects of leading-edge protuberances are more notable at a higher reduced *** the instantaneous aerodynamic loads of the wavy airfoil,there is an observable reduction in fluctuations compared with baseline ***,spectral analysis is applied to quantitatively undercover the nonstationary features of the instantaneous aerodynamic *** is found that the leading edge protuberances can reduce the harmonics of the aerodynamic force signal,and enhance the stability of the aerodynamic loads under different reduced *** conclusion,leading-edge protuberances are found effective to reduce the fluctuation characteristics of the aerodynamic loads during the dynamic stall process,and help to improve the stability and prolong the service life of the wind turbine blades.

关键词： Wind turbine airfoil Dynamic stall Loads control Leading-edge protuberance Aerodynamic experiment

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Straight-Leaned Blade Aerodynamics of A Turbine Nozzle Blade Row with Low Span-Diameter Ratio

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j.urnal of Thermal Science 2000年第1期9卷 51-52页

作者： N. X. Chen Y. j. xu W.G Huang Institute of Engineering Thermophysics Chinese Academy of Sciences P.O. Box 2706 Beijing 100080

Compound-leaned blades have been applied for the design of turbomachinery for reducing secondary flow losses and then improving the aerodynamic performance. The aerodynamics features are not clear enough so far and, therefore, have been investigted by many authors experimentally and numerically. The present study on turbomachinery aerodynamics is emphasized on the leaning effects of straight-leaned turbine nozzle blades With low span-diameter ratio (less than 0.1). This Kind of blades has relatively low efficiency. This is due to that the blades are too short and then the loss contours of both tip and hub surfaces are merged with each other. How to increase the efficiency efficiency becomes of the important subj.cts, which is faced to the turbomachinery community. Effects of straight-leaned blades in a turbine nozzle blade row with low span-diameter ratio have been assessed using three-dimensional steady Reynolds-averaged Navier-Stokes computations.

关键词：透平机导向器叶片空气动力学

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