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Microstructures of Sintered Mo-Cu Alloys with Mechanically Activated Powder

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Rare Metals 2001年第2期20卷 112-116页

作者： Chengchang Jia, Zhong He, Xuekuan Su, Ziqin Yang, Jun Zhao, Zizhang Xie (School of Materials Science and Engineering, University of Science and Technology beijing, beijing 100083, China Beliing Polytechnic University, beijing 100022, beijing) 北京科技大学北京 100083 北京工业大学北京 100022

Mechanical activation and liquid phase sintering were used to manufacture high performance Mo-Cu alloy and develop new processes. The microstructures and properties of the alloy were investigated. The experimental results showed that: (1) the ball milled Mo/Cu powder has lamellar structure, (2) the microstructures of the sintered Mo-Cu alloy were homogenous compound structures of adhesive phase Cu linking Mo grains, (3) Mo grains frequently strung or gathered in Cu phase, and (4) the full densities of Mo-Cu alloy was achieved through sintering and special densification process. As a result, the properties of the alloy are good enough to satisfy various requirements.

关键词： Mo-Cu alloy powder metallurgy mechanical activation microstructure

Seasonal variations and bioavailability of inorganic phosphorus in soils of Yeyahu Wetland in beijing,China

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International Journal of Sediment Research 2011年第2期26卷 181-192页

作者： ZHANG Jing,LI Min,LIU Shuang,LIU Yujin,ZHANG Liqiang,CAO Qi,and SUN Dezhi 1 Ph.D.student,~ 2 Assoc,Prof,~(3,6) Master,~7 Prof,College of Environmental Science and Engineering,beijing Forestry University,beijing,P.R.China,100083 ~(4,5) Senior Engineer,beijing Yanqing Yeyahu Wetland Nature Reserve,beijing,P.R.China,102101 Ph.D. student College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083 Assoc. Prof. College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083 Master College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083 Senior Engineer Beijing Yanqing Yeyahu Wetland Nature Reserve Beijing P.R. China 102101 Prof. College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083

Phosphorus(P) in soils has an important influence on the development and productivity of wetland. The objective of this study was to investigate the distribution,bioavailability and seasonal variations of inorganic phosphorus(IP) in soils of Yeyahu *** results showed that the concentration of Ca-bound P(Ca-P) remained the main occurrence in all IP fractions despite the season,at the same time the Al-bound P(Al-P) was always the lowest IP fraction despite the ***-P and Fe-bound P (Fe-P) concentration were all reached the highest value in May and the lowest in November,which was opposite to the occluded P(Oc-P) *** notable higher Oc-P concentration in November observed in this study was probably due to the decomposition of plants and the subsequently releasing of oxides to ***-P didn’t change much with season *** P(Ex-P) and Oc-P were all positively correlated with soil moisture content and organic matter content,but Al-P was negatively correlated with these two soil *** a stable form,Ca-P was not associated with soil ***-P,Fe-P and Ca-P might contribute to the storage of P in studied wetland with the principle component analysis *** concentration rank order of the bio-available P in soils was generally as follows:Olsen-P > Algal available P(AAP) > Water soluble P(WSP) > Readily desorbed P(RDP).Olsen-P was positively correlated with Ex-P and Oc-P,and it was thought to be a more suitable indicator for bio-available P in soils.

关键词： Inorganic phosphorus fractions Distribution Bioavailability Seasonal variations

PARALLEL ROSENBROCK METHODS FOR SOLVING STIFF SYSTEMS IN REAL-TIME SIMULATION

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Journal of Computational Mathematics 2000年第4期18卷 375-386页

作者： Li-rong Chen De-gui Liu (beijing institute of Computer Application and Simulation Technology, beijing 100854, China) 北京计算机应用与仿真技术所北京 100854

In this paper parallel Rosenbrock methods in real-time simulation are presented on parallel computers. Their construction, their convergence and their numerical stability are studied, and the numerical simulation expe... 详细信息

关键词： Rosenbrock methods stiff system real-time simulation parallel algorithms

Preparation of a Novel Micro/nano Tubes via Electrospun Fiber as a Template

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Journal of Materials Science & Technology 2004年第5期20卷 613-616页

作者： Taiqi LIUSchool of Materials and Chemical Engineering, beijing Institute of Petro-chemical Technology, beijing 102617, China Sch. of Mat. and Chem. Eng. Beijing Inst. of Petrochem. Technol. Beijing 102617 China

Poly (para-xylylene) hollow fibers with inner diameters can be prepared via template fibers electrospun from solutions. The PPX is deposited from the vapor phase and the template fiber is selectively removed by heat treatment or solvent extraction. The PPX is partially crystalline and the crystal modification depending on the route is used to extract the template fiber. The thermal stability of the hollow fibers is only slightly reduced relative to the bulk material and the same holds for the UV-stability.

关键词： Electrospinning Fiber Chemical vapor deposition Physical vapor deposition Crystal Conductivity

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Saturated models

Chinese Science Bulletin 1998年第7期43卷 562-564页

作者： CHEN Guolong Department of Mathematics, beijing Normal University, beijing 100875, China Department of Mathematics Beijing Normal University Beijing China

An equivalent description of saturated models is given, and some properties of countable saturated models, almost saturated models and full models are discussed. New proofs of two important theorems of the related doc... 详细信息

关键词： almost saturated model full model power type.

GENETIC ANALYSIS OF ANOMALOUS VARIATION OF WATER TABLE IN CHANGPING WELL, beijing

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地震地质 1991年第4期 312-316+311页

作者： Yang Hui-nian(Institute of Geology, State Seismological Bureau, beijing 100029)

Field investigation on hydrogeological environment around Changping well reveals that the anomalous uprise of ’water table begining from Oct. 1988 was mainly caused by the leakage of water from the channel leading to... 详细信息

关键词： Changping well Anomalous water table Shisanling Reservoir Paleochannel Water diversion Pecolation recharge

CONVERGENCE PROPERTIES OF A MODIFIED BFGSALGORITHM FOR MINIMIZATION WITHARMIJO-GOLDSTEIN STEPLENGTHS

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Journal of Computational Mathematics 1999年第6期17卷 645-652页

作者： Nai-yang Deng Zheng-feng Li(Department of Mathematics, beijing Agricultural Engineering University, beijing 100083,China) 北京农业工程大学数学系北京 100083 北京农业工程大学数学系北京

The line search strategy is crucial for an efficient unconstrained optimization algorithm. One of the reason why the Wolfe line searches is recommended lies in that it ensures positive definiteness of BFGS updates. When gradient information has to be obtained costly, the Armijo-Goldstein line searches may be preferred. To maintain positive difiniteness of BFGS updates based on the Armijo-Goldstein line searches, a slightly modified form of BFGS update is proposed by I.D. Coope and C.J. Price (Journal of Computational Mathematics, 13 (1995), 156-160), while its convergence properties is open up to now. This paper shows that the modified BFGS algorithm is globally and superlinearly convergent based on the Armijo-Goldstein line searches.

关键词： BFGS methods convergence superlinear convergence

Investigation on Coal-Oxygen Scrap Melting Process

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 61-64页

作者： Rong Xhu Yanhui Sun Yongquan Qiu Metallurgy School, UST beijing, beijing 100083, China Metallurgy School UST Beijing Beijing 100083 China

Investigation on the coal-oxygen scrap melting process shows that using internal-combustion coal-oxygen burner to melt scrap is feasible. Among four types of coal-oxygen furnaces-oxygen burner melting furnace is better than other types on the quotas of process. The metal yield is 95%～97%, the melt down carbon and sulphur contents are >1.0% and <0.080% respectively for this melting furnace. The coal-oxygen scrap melting process would have a significant effect on the technological transformation of EAF and BOF in China.

关键词： scrap melting coal-oxygen burner steelmaking

Nonlinear Theory on Dynamic Controlling Interface Patterns DuringSolidification of a Dilute Binary Alloy

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 253-258页

作者： Zidong Wang Hanqi Hu(Material Science and Engineering School, University of Science and Technology beijing, beijing 100083, China) Material Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

In non-equilibrium nonlinear region, the nonlinear equations of time dependence of perturbation amplitude at the solid/liquidinterface during solidification of a dilute binary alloy are established on the base of assuming that there is local equilibrium at the solid/liquid interface and considering that curvature, temperature and composition at the solid/liquid interface which are related to the perturbation amplitude are nonlinear. As a result, patterns at the solid/liquid interface during solidification process, which is from nonsteadystate to steady state can be controlled by these nonlinear equations.

关键词： nonlinearity solidification, dilute binary alloy, dynamic control