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EXPERIMENTS ON HYDRODYNAMIC INTERACTION BETWEEN 3-D OVAL AND WALL

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Journal of Hydrodynamics 2007年第1期19卷 121-126页

作者： SUN Ke SHENG Qi-hu zhang liang li feng-lai College of Shipbuilding Engineering Harbin Engineering University Harbin 150001 China

The boundary hydrodynamic interaction of a 3-D oval body was experimentally surveyed for different cases. The regression method was employed to fred the experimental formulae of hydrodynamic coefficients relating to the attack angle, clearance to wall, and moving speed. The mechanism of interaction was discussed. The experimental results show that there exists a lifting effect, similar to wings in flow. The lifting effect is remarkable. The boundary hydrodynamic interaction of the small aspect ratio model is almost linearly dependent on the attack angle, but the effect of the moving speed of the body on the hydrodynamic coefficients is very small. The effect of clearance is related to the geometric shape. The boundary hydrodynamic interaction always enhances the lifting effect if the clearance is small.

关键词： hydrodynamic coefficient model experiment,boundary interaction oval

Stability Analysis and Design of Impulsive Control Lorenz Systems Family

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Communications in Theoretical Physics 2009年第5期51卷 869-875页

作者： YU Yong-Bin zhang Hong-Bin zhang feng-li YU Jue-Bang liAO Xiao-feng School of Computer Science and Engineering University of Electronic Science and Technology of China Chengdu 610054 China School of Electronic Engineering University of Electronic Science and Technology of China Chengdu 610054 China College of Computer Science Chongqing University Chongqin 400044 China

Lorenz systems family unifying Lorenz system, Chen system and Lü system is a typical chaotic family. In this paper, we consider impulsive control Lorenz chaotic systems family with time-varying impulse intervals. By establishing an effective tool of a set of inequalities, we analyze the asymptotic stability of impulsive control Lorenz systems family and obtain some new less conservative conditions. Based on the stability analysis, we design a novel impulsive controller with time-varying impulse intervals. Illustrative examples are provided to show the feasibility and effectiveness of our method. The obtained results not only can be used to design impulsive control for Lorenz systems family, but also can be extended to other chaotic systems.

关键词： Lorenz systems family impulsive chaotic system asymptotic stability

Succession and Enhancement Mechanism of Ecosystem Productivity in the De-farming Area of the Ecotone Between Agriculture and Animal Husbandry in North China

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Agricultural Sciences in China 2008年第4期7卷 487-496页

作者： DU Xiong zhang li-feng College of Agronomy Agricultural University of Hebei Baoding 071001 P.R. China zhangbei Agricultural Resource and Ecological Environment Key Field Research Station Ministry of Agriculture Zhangjiakou 076450 P. R. China

The succession and enhancement mechanism of the ecosystem productivity with the characteristics ot de-tarmlng in me ecotone between agriculture and animal husbandry in North China was discussed in order to provide an ideaology or a technical basis for maintaining the impetus of ecological restoration and economic development in this region. A case study was applied in combination with the theoretical analysis. The results indicated that the biomass productivity of the de-farming subsystem decreased by 38.4-72.3% compared with that of farming subsystem in the ecosystem. The main function of de-farming subsystem was focused on ecological productivity, it caused the ideal beneficial recycling ‘defarming → planting grass → raising animals → earn money＇ difficult to be realized. With the differentiation of de-farming subsystem, the natural and social resources input to the farming subsystem were accumulated. This laid a basis for the new attributes of economic productivity to be upgraded. The case study indicated that the economic productivity of the ecosystem was increased by 8.85-13.35 times due to re-coupling between the de-farming subsystem and the farming subsystem as well as coupling between microhabitat differentiation and crop production in the subsystems, where the microhabitat differentiation could enrich water and fertilizer in the same field. It was concluded that the important mechanisms to enhance the system productivity in the ecotone between agriculture and animal husbandry of North China included structure rebuilding and opening of the de-farming ecosystem and taking the advantage of complementary cooperative production among different regions under the market economy and rebuilding an open agro-pasture production structure,

关键词： ecosystem after de-farming biomass productivity economic productivity resource and environment theecotone between agriculture and animal husbandry of North China

Some New Exact Solutions of Jacobian Elliptic Function of Petviashvili Equation

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Communications in Theoretical Physics 2008年第6期49卷 1557-1560页

作者： zhang ling zhang li-feng li Chong-Yin WANG Tie TAN Yan-Ke Institute of Meteorology PLA University of Science and Technology Laboratory of Applied Geophysics Nanjing 211101 China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics the Chinese Academy of Sciences Beijing 100029 China

By using the modified mapping method, we find new exact solutions of the Petviashvili equation. The solutions obtained in this paper include Jacobian elliptic function solutions, combined Jacobian elliptic function so... 详细信息

关键词： Petviashvili equation Jacobian elliptic function modified mapping method

A Compact System of Capacitively Coupled Contactless Conductivity Detection Based on the Square Wave Excitation Signal for Capillary Electrophoresis

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Chinese Chemical Letters 2006年第9期17卷 1229-1232页

作者： Shui feng zhang li Shi WANG Zhi DANG College of Environmental Science and Engineering South China University of Technology Guangzhou 510640

This paper reported a compact system of capacitively coupled contactless conductivity detection （C4D） based on the square wave excitation voltage for capillary electrophoresis, and it exhibited excellent sensitivity at the optimal frequency of 198 kHz. The feasibility and sensitivity of this detector was demonstrated by simultaneous detection of thirteen ions including alkali, alkaline earth and heavy metal ions. And the detection limits （S/N 3） were in the range of 0.2-1μmol/L for Mn^2＋, K^＋, Na^＋, Mg^2＋, Ca^2＋, li^＋, Ba^2＋, and 7-25 μmol/L for Ni^2＋, Cu^2＋, Cd^2＋, Pb^2＋, Co^2＋, Zn^2＋.

关键词： Capillary electrophoresis square wave excitation signal contactless conductivitydetector metal ions.

The Quantitative Evaluation of Output Efficiency in Different Cropping Patterns

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Agricultural Sciences in China 2006年第2期5卷 98-102页

作者： liU Yu-hua zhang li-feng College of Agronomy Agricultural University of Hebei Baoding 071001 P.R.China

Quantitative indexes such as land equivalent ratio, yield equivalent and value of output equivalent were used to evaluate output efficiencies of different cropping patterns, i.e., sequential cropping, intercrops and crop rotation. Compared to single cropping, land use efficiencies under sequential cropping, intercrops and crop rotation were raised by 62, 38 and 21%, respectively. The unit area yield under sequential cropping, intercrops and crop rotation were raised by 63, 29 and 16%, respectively. The unit area value was also enhanced under sequential cropping and intercrops, 76 and 35% higher than that under single cropping. The paper provides a useful tool for comparing farm output efficiency and build up a theoretical basis for further research on output efficiency of various cropping patterns in the future.

关键词： sequential cropping intercrops rotation cropping patterns quantitative evaluation

Thermal stability of liFePO_4/C-liMn_2O_4 blended cathode materials

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Science China(Technological Sciences) 2017年第1期60卷 58-64页

作者： DU YuanChao HUANG XiaoPeng zhang KeYu liANG feng li QiuXia YAO YaoChun DAI YongNian Faculty of Chemistry and Chemical Engineering Yunnan Normal University Kunming 650500 China

Safety is important to lithium ion battery materials. The thermal stability of liFePOa/C-liMn204 blended cathode materials is characterized by using TG, XRD, and SEM etc. The results show that liFePO4/C-liMn2O4 possesses a worse thermal stability than pure spinel liMn2O4 and pure olivine liFePO4/C. When liFePO4/C-liMn2O4 blended cathode materials are sintered at 500℃ under Ar atmosphere, the sintered cathode materials emit O2, and appear impurity phases （li3PO4, Fe2O3, Mn3O4）. It is deduced that some chemical reactions take place between different materials, which leads to a worse discharge specific capacity. liFePO4/C-liMn2O4 blended cathode materials, therefore, need to be managed and controlled strictly for the sake of ther- mal stability and safety.

关键词： liFePO4/C-liMn2O4 blended cathode materials impurity phases thermal stability

Aluminum matrix composites reinforced by molybdenum-coated carbon nanotubes

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International Journal of Minerals,Metallurgy and Materials 2011年第6期18卷 695-702页

作者： Jun-hui Nie Cheng-chang Jia Na Shi Ya-feng zhang Yi li XianJia School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

To extend the application of carbon nanotubes （CNTs） and explore novel aluminum matrix composites,CNTs were coated by molybdenum layers using metal organic chemical vapor deposition,and then Mo-coated CNT （Mo-CNT）/Al composites were prepared by the combination processes of powder mixing and spark plasma *** influences of powder mixing and Mo-CNT content on the mechanical properties and electrical conductivity of the composites were *** results show that magnetic stirring is better than mechanical milling for mixing the Mo-CNTs and Al *** electrical conductivity of the composites decreases with increasing Mo-CNT *** the Mo-CNT content is 0.5wt%,the tensile strength and hardness of Mo-CNT/Al reach their maximum *** tensile strength of 0.5wt% Mo-CNT/Al increases by 29.9%,while the electrical conductivity only decreases by 7.1%,relative to sintered pure *** phase analysis of Mo-CNT/Al composites reveals that there is no formation of Al carbide in the composites.

关键词： carbon nanotubes aluminum matrix composites molybdenum layer mechanical properties electrical conductivity

Determination of n+1 Gamete Transmission Rate of Trisomics and Location of Gene Controlling 2n Gamete Formation in Chinese Cabbage(Brassica rapa)

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Journal of Integrative Plant Biology 2009年第1期51卷 29-34页

作者： Cheng-He zhang Xiao-feng li Shu-Xing Shen He Yuan Shu-Xin Xuan College of Horticulture Agncultural University of Hebei Baoding 071001 China

A set of trisomics of Chinese cabbage was used for determining the n-I-1 gamete transmission rate and locating the gene controlling 2n gamete formation on the corresponding chromosome. The results showed that the transmission rates of extra chromosomes in different trisomics varied from 0% to 15.38% by male gametes and from 0% to 17.39% by female gametes. Of the nine F2 populations derived from the hybridizations between each trisomic and Bp058 （2n gamete material）, only Tri- 4xBp058 showed that the segregation ratio of plants without 2n gamete formation to plants with 2n gamete formation was 10.38：1, which fitted the expected segregation ratio of the trisomics （AAa） based on the 7.37% of n＋l gamete transmission through female and 5.88% through male. In other populations the segregation ratios varied from 2.48：1 to 3.72：1, which fitted the expected 3：1 segregation ratio of the bisomics （Aa）. These results suggested that the gene controlling 2n gamete formation in Chinese cabbage Bp058 was located on chromosome 4. Further trisomic analysis based on the chromosome segregation and the incomplete stochastic chromatid segregation indicated that the gene locus was tightly linked to the centromere.

关键词： Chinese cabbage gene location n+l gamete transmission primary trisomics 2n gametes.