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Search Results: 1 - 10 of 112583 matches for " XU Da-Ping "
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Hybrid qualitative and quantitative control method

YANG Xi-yun,XU Da-ping,BAI Yan,
,徐大平,白 焰

控制理论与应用 , 2004,
Abstract: Quantitative control with accurate mathematical model has high precision and its performance is restricted by parameters varying while qualitative control often has both strong robustness and low precision. Combining the merits of both, an algorithm of hybrid qualitative and quantitative control (HQQC) was proposed without accurate math model. Bond graph model without causality stroke was firstly built in the algorithm, the qualitative representations were analyzed and illustrated with improved bond graph theory. Then control equation of HQQC was deduced from simplifying qualitative representations. Comparing with PID, simulation results demonstrate the robustness and transient performance of the algorithm, especially when the plant is time-vary and nonlinear.
The Environment, Not Space, Dominantly Structures the Landscape Patterns of the Richness and Composition of the Tropical Understory Vegetation
Yue-Hua Hu, Da-Yong Sheng, Yang-Zhou Xiang, Zeng-Jiang Yang, Da-Ping Xu, Ning-Nan Zhang, Lei-Lei Shi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081308
Abstract: The mechanisms driving the spatial patterns of species richness and composition are essential to the understanding of biodiversity. Numerous studies separately identify the contributions of the environment (niche process) and space (neutral process) to the species richness or composition at different scales, but few studies have investigated the contributions of both types of processes in the two types of data at the landscape scale. In this study, we partitioned the spatial variations in all, exotic and native understory plant species richness and composition constrained by environmental variables and space in 134 plots that were spread across 10 counties in Hainan Island in southern China. The 134 plots included 70 rubber (Hevea brasiliensis) plantation plots, 50 eucalyptus (Eucalyptus urophylla) plantation plots, and 14 secondary forest plots. RDA based variation partitioning was run to assess the contribution of environment and space to species richness and composition. The results showed that the environmental variables alone explained a large proportion of the variations in both the species richness and composition of all, native, and exotic species. The RDA results indicated that overstory composition (forest type here) plays a leading role in determining species richness and composition patterns. The alpha and beta diversities of the secondary forest plots were markedly higher than that of the two plantations. In conclusion, niche differentiation processes are the principal mechanisms that shape the alpha and beta diversities of understory plant species in Hainan Island.
Strong Neutral Spatial Effects Shape Tree Species Distributions across Life Stages at Multiple Scales
Yue-Hua Hu, Guo-Yu Lan, Li-Qing Sha, Min Cao, Yong Tang, Yi-De Li, Da-Ping Xu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038247
Abstract: Traditionally, ecologists use lattice (regional summary) count data to simulate tree species distributions to explore species coexistence. However, no previous study has explicitly compared the difference between using lattice count and basal area data and analyzed species distributions at both individual species and community levels while simultaneously considering the combined scenarios of life stage and scale. In this study, we hypothesized that basal area data are more closely related to environmental variables than are count data because of strong environmental filtering effects. We also address the contribution of niche and the neutral (i.e., solely dependent on distance) factors to species distributions. Specifically, we separately modeled count data and basal area data while considering life stage and scale effects at the two levels with simultaneous autoregressive models and variation partitioning. A principal coordinates of neighbor matrix (PCNM) was used to model neutral spatial effects at the community level. The explained variations of species distribution data did not differ significantly between the two types of data at either the individual species level or the community level, indicating that the two types of data can be used nearly identically to model species distributions. Neutral spatial effects represented by spatial autoregressive parameters and the PCNM eigenfunctions drove species distributions on multiple scales, different life stages and individual species and community levels in this plot. We concluded that strong neutral spatial effects are the principal mechanisms underlying the species distributions and thus shape biodiversity spatial patterns.


物理学报 , 1983,
Abstract: In this papar, we calculated the influence of 5d-4f mixing caused by odd parity crystal field on level splitting of Ce3+ ions in CaF2 and SrF2 lattices. Results indicated that odd parity crystal field effect on level splitting may be fairly large. For lower levels in CaF2 the contribution of odd parity crystal field may amount to 15-30%. The order of 1st and 2nd excited states even reverses. On the other hand, it has been shown that configuration mixing is one of the possible mechanisms causing the extension of radial wave fanctions of ions in crystal.


物理学报 , 1986,
Abstract: The temperature dependence of the anisotropy constants K1, K2 and the anisotropy field HA. of R2Fe14B (R = Ce, Pr, Gd) have been measured in temperature range of 1.5 K to 300 K. And the contribution of Pr3+ ions to the magnetocrystalline anisotropy of Pr2Fe14B compound was calculated by the single ion theory. The result is semiquantitatively consistent with the experiment.
Soil macropore characteristics under typical vegetations in Liupan Mountains

SHI Zhong-jie,WANG Yan-hui,XU Li-hong,YU Peng-tao,XIONG Wei,XU Da-ping,

应用生态学报 , 2007,
Abstract: The radius and density of soil macropores under eight typical vegetations in Liupan Mountains of Northwest China were studied by using water breakthrough curves and Poiseuille equation.The results indicated that the radii of soil macropores ranged from 0.4 mm to 2.3 mm,and the weighted mean radii ranged from 0.57 mm to 1.21 mm,with a mean of 0.89 mm.The density of soil macropores ranged from 57 individuals per dm2 to 1 117 individuals per dm2,with a mean of 408 individuals per dm2.The macropores with radii bigger than 1.4 mm had a lower density,accounting for only 6.86% of the total.The area proportion of soil macropores ranged from 0.76% to 31.26%,with a mean of 10.82%.In study area,the density of soil macropores was higher in broadleaf forest than in coniferous forest,but basically the same in sub-alpine meadow and in broadleaf forest,as well as in shrubs and in coniferous forest.As for the area proportion of soil macropores,it was also higher in broadleaf forest than in coniferous forest,but basically the same in shrubs and in broadleaf forest soil,as well as in sub-alpine meadow and in coniferous forest.
Effects of Phosphorus Supply on Growth and Foliar Nutrition of Dalbergia odorifera Seedlings

赵霞, 徐大平, 刘小金, 张宁南, 杨曾奖
, XU Da-Ping, LIU Xiao-Jin, ZHANG Ning-Nan, YANG Zeng-Jiang

植物研究 , 2018, DOI: 10.7525/j.issn.1673-5102.2018.02.008
Abstract: 设置0、15、30、60、100、150 mg P·株-1等6个磷素处理开展降香黄檀幼苗盆栽试验,测定各处理幼苗的生长、生物量、叶片养分含量等指标,采用临界浓度法确定降香黄檀幼苗的适宜施磷量,从而探讨不同磷素水平对降香黄檀幼苗生长和叶片养分状况的影响,揭示其磷素需求规律以及适宜的磷供应范围。结果显示磷肥能促进幼苗生长和生物量的积累,而且随施磷量的增加,各指标呈现先升高后降低的趋势,最高值出现在60 mg P·株-1处理,其苗高、地径、叶面积、生物量分别为对照的3.07、2.35、49.21和24.25倍。施磷显著降低幼苗叶片氮、钾含量,提高磷、镁含量,其中30、60、100 mg P·株-13个处理间叶片磷含量差异不显著,约为对照的1.65倍。根据幼苗生物量与叶片磷含量、氮钾含量比、磷钾含量比的抛物线关系,确定叶片最适磷含量范围为1.35~2.32 g·kg-1,由此推断降香黄檀幼苗最适宜的施磷量为60~100 mg P·株-1。
Effects of Different Cultivation Strategies on Endogenous Hormones Accumulation of Dalbergia odorifera

王玥琳, 徐大平, 杨曾奖, 刘小金, 洪舟, 张宁南
WANG Yue-Lin
, XU Da-Ping, YANG Zeng-Jiang, LIU Xiao-Jin, HONG Zhou, ZHANG Ning-Nan

植物研究 , 2018, DOI: 10.7525/j.issn.1673-5102.2018.05.008
Abstract: 为了了解不同栽培措施对降香黄檀叶片内源激素的影响,本研究通过铺设修枝、移植、钾肥、乙烯4个试验,分析各处理叶片激素含量特征。结果表明:修枝实验中,重度修枝处理IAA、GA3、ZR、ABA含量均最大,分别为69.849、6.619、8.805、77.998 ng·g-1。移植各处理中,去冠移处理IAA、ZR含量最高分别为73.195和9.472 ng·g-1,而其ABA含量最低为52.001 ng·g-1,GA3含量最高的为断根处理8.418 ng·g-1。IAA、ZR、GA3含量K1钾肥配比最高分别为75.188、8.383、6.127 ng·g-1;ABA最大含量71.082 ng·g-1为CK处理。乙烯试验中,CK处理的IAA、GA3含量最高分别为47.762、4.967 ng·g-1;E2.5%处理的ABA含量96.94 ng·g-1最高。E0.1%处理的ZR含量最高为9.378 ng·g-1。修枝对GA3/ABA和ZR/GA3影响较大,其最小值分别比最大值降低了29.7%、19.0%。移植对IAA/ABA、GA3/ABA影响较大,最小值比最大值依次降低了52.47%和51.47%。树干注射乙烯和钾肥对IAA/ABA、GA3/ABA影响较大,乙烯试验最小值分别比最大值降低了55.4%、49.2%,钾肥试验最小值分别比最大值降低了48.8%和37.1%。
(E)-N′-(3,5-Dibromo-2-hydroxybenzylidene)-2-nitrobenzohydrazide methanol solvate
Heng-Yu Qian,Da-Ping Qu
Acta Crystallographica Section E , 2009, DOI: 10.1107/s160053680903311x
Abstract: In the title compound, C14H9Br2N3O4·CH3OH, the Schiff base molecule adopts an E geometry with respect to the C=N bond and the benzene rings are oriented at a dihedral angle of 45.3 (2)°. An intramolecular O—H...N hydrogen bond helps to establish the conformation. In the crystal, the methanol solvent molecule is linked to the Schiff base molecule through an O—H...O hydrogen bond and intermolecular N—H...O hydrogen bonds link the components to form layers parallel to the bc direction.
(E)-N′-(2-Hydroxy-3,5-diiodobenzylidene)-2-nitrobenzohydrazide methanol solvate
Heng-Yu Qian,Da-Ping Qu
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809033091
Abstract: In the title compound, C14H9I2N3O4·CH3OH, the Schiff base molecule adopts an E geometry with respect to the C=N bond and the dihedral angle between the benzene rings is 45.0 (2)°; an intramolecular O—H...N hydrogen bond is present. In the crystal, adjacent Schiff base molecules are linked by methanol solvent molecules through intermolecular N—H...O and O—H...O hydrogen bonds, forming dimers.
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