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In situ reproductive organs of Early Cretaceous ferns from Northeast china

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Chinese Science Bulletin 1997年第23期42卷 1977-1980,2026页

作者： DENG Shenghui and chen Fen1. Research Institute of Petroleum and Development, beijing 100083 2.{2. university of Geosciences, beijing 100083,{2. Research Institute of Petroleum and Development Beijing china university of Geosciences Beijing China

FILICOPSIDA is a predominant group of the Early Cretaceous floras of Northeast china, whichapproximates 100 species and accounts for more than one third of the floras. The majority ofthis group are of great importance and significance in stratigraphy. The previous studies ofthese ferns are mainly morphological, with only a few concerning the in situ spores andsporangia. In recent years. the authors have carried out a research project on the in situreproductive organs of the Early Cretaceous ferns from/ basins of Inner Mongolia, Liaoning,Jilin and Heilongjiang of Northeast china. The study focuses on 35 species of 17 genera be-longing to 10 families. The present note briefly introduces the results of this study by listingsome representative species.

关键词： Northeast china Early Cretaceous Filicopsida in situ reproductive organs.

Fractal Structure of the Core Loss Spectrum of Co-based Amorphous Soft Magnetic Alloy with Constant Permeability

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International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 54-56页

作者： Yiping chen (Applied Science School, university of Science and {2. beijing, beijing 100083, china) Applied Science School University of Science and Technology Beijing Beijing 100083 China

In order to check the traditional core loss formula, the core loss spectrum P(f) of Co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range from 10 kHz to 2.0 kHz and at Bm = 0. 1 T,the P(f) has the fractal structure P (f) = Po, and with the increasing of induced anisotropy energy Ku, the fractal dimension Dfrises, thus the total power loss at high frequency increases and the frequency characteristic of P(f) becomes worse.

关键词： amorphous soft magnetic alloy constant permeability core loss fractal

MEAM Potential with Angular Dependence for TiAl

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Rare Metals 2001年第1期20卷 13-17页

作者： Xiaodong Ni, Xitao Wang, Guoliang chen (Physics Department, university of Science and {2. beijing, beijing 100083, china State Key Laboratory for Advanced Metals and Materials, university of Science and {2. beijing, beijing 100083, china) Univ Sci & Technol beijing Dept Phys Beijing 100083 Peoples R China Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

The modified embedded atom method (MEAM) is an empirical extension of the embedded atom method (EAM) that includes angular forces. By fitted to the lattice constants, the cohesive energy, the APE (anti-phase boundary) energy, and the vacancy formation energy of TiAl, an accurate MEAM potential is obtained for the TiAl system with L10 structure. The calculation results of the properties of TiAl are in good agreement with experiments and the results of first principle (F.P.) calculations.

关键词： embedded atom method TiAl alloy angular dependence potential intermetallics

Application of Diagonal Recurrent Neural Network toDC Motor Speed Control Systems

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International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 68-71页

作者： Jing Wang Hui chen Information Engineering School, university of Science and {2. beijing, beijing 100083, china Information Engineering School University of Science and Technology Beijing Beijine 100083 China

A new kind of dynamic neural network--diagonal recurrent neural network (DRNN) and its learning method and architecture are presented. A direct adaptive control scheme is also developed that is applied to a DC (Direct Current) speed control system with the ability to auto-tune PI (Proportion Integral) parameters based on combining DRNN with PI controller. The simulation results of DRNN show better control performances and potential practical use in comparison with PI controller.

关键词： diagonal recurrent neural network PI controller DC Motor speed control system

NON-EQUILIBRIUM SEGREGATION OF Si ON Al-0.35 wt-% Si ALLOY SURFACE

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Acta Metallurgica Sinica(English Letters) 1993年第8期6卷 98-101页

作者： chen Niug YU Zongsen university of Science and {2. beijing,beijing,china professor,Department of Materials Physics,university of Science and {2. beijing,beijing 100083,china beijing Univ of Science and Technology Beijing China

Si segregation was observed in the vacancy condensation pits,formed by supersaturated vacancies beneath the oxidation layer of Al-0.35wt-％Si alloy,by optical microscopy,X- ray photoelectron spectroscopy and microhard... 详细信息

关键词： non-equilibrium segregation vacancy AI-Si alloy surface Si

Change Laws of Flake's Temperature during Making a Diamond Film by DC-PJ

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 97-102页

作者： Xuhong chen Lihe Zhao Fanxiu Lu(Mechanical Engineering School, university of Science and {2. beijing, beijing 100083, china) Mechanical Engineering School University of Science and Technology Beijing Beijing 100083 China

When making a diamond film by direct current plasma jet, a kind piece of flake is used as a base body Which the film can beattached to. The flake's temperature is unstable. Therefore, some experiments and constructed mathematical models, which were solvedby computer, were done. The results show that the flake's temperature is influenced by many factors and the mains are plasma jet powerand vacuum pressure. Through adjusting the two parameters, the flake's temperature can be accurately controlled, furthermore, diamondfilms' quality would be improved. Lowering sediment platform's temperature has a little effect to the flake's temperature at present technology conditions.

关键词： CVD (Chemical Vapor Deposition) plasma, impact heat transfer

Laboratory Investigation of Zinc Recovery fromEAF Dust by Bath Smelting Reduction

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International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 18-23页

作者： Weiqing chen Tarek El Gammal Metallurgy School, university of Science & {2. beijing, beijing 100083, china Institute for Ferrous Metallurgy, Aachen university of {2., Germany Univ Sci & Technol beijing Met Sch Beijing 100083 Peoples R China Aachen Univ Technol Inst Ferrous Met Aachen Germany

Bath smelting reduction for recovering zinc from EAF (Electric Arc Furnace) dust has been investigated in the laboratory. A degree of zinc volatilization of more than 99% was obtained from the process. Temperature has a clear influence on the reduction rate of ZnO in slag. The reduction rate of (ZnO) by [C] is the first order with respect to the content of ZnO in the slag. The apparent activation energy of the (ZnO) reduction reaction is 312.kJ/mol at 1300-1500℃.

关键词： EAF dust ZnO smelting reduction reduction rate

Effect of As Interstitial Diffusionon on the Properties of Undoped Semi-insulating LECGaAs

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Rare Metals 2001年第3期20卷 187-191页

作者： Ruixia Yang, Fuqiang Zhang, Nuofu chen 1) Hebei university of {2., Tianjin 300130, china 2. Institute of Semiconductors, Chinese Academy of Sciences, beijing 100083, china Hebei Univ Technol Tianjin 300130 Peoples R China Chinese Acad Sci Inst Semicond Beijing 100083 Peoples R China

Annealing was carried out at 950 and 112. degreesC under various As pressure for undoped (ND) semi-insulating (SI) LECGaAs. The effects of annealing on native defects and electrical properties were investigated. Experimental results indicate that, after an annealing at 950 degreesC for 14 h under low As pressure, the Hall mobility decreases and the resistivity increases dramatically for the samples. These changes in electrical properties are due to the generation of intrinsic acceptor defects, and the generation of the intrinsic acceptor defects originates from the outdiffusion of As interstitial at high temperature. The generation of the intrinsic defects and these changes in electrical properties can be suppressed by increasing the applied As pressure during annealing. The concentration of the main donor defect E12.(AsGaVGa) can be decreased by about one order of magnitude by an evacuated annealing at 112. degreesC for 2.8 h followed by a fast cooling. The decrease in E12.concentration can also be suppressed by increasing the As pressure during annealing.

关键词： semi-insulating GaAs intrinsic acceptor defects As interstitial indiffusion As pressure annealing

Kinetics of Evaporation of Zn and Pb from Carbon-bearing Pellets Made of Dust Containing Zn-Pb-Fe Oxides

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International Journal of Minerals,Metallurgy and Materials 2000年第3期14卷 178-183页

作者： Weiqing chen, Dongyan Wang, Rongzhang Zhou, Zongcai Lin (Metallurgy School, university of Science and {2. beijing, beijing 100083, china) Metallurgy School University of Science and Technology Beijing Beijing 100083 China

The influence of reduction temperature, size of coal powder and the carbon content on the evaporation rates of Zn and Pb in pellets made of ZnO-PbO-FeO bearing dust has been investigated between 1100-1300℃. The evaporation rate of Zn and Pb obtained from the experiments has been analyzed with kinetic models. The results show that the control step for evaporation of Zn is reduction reaction of ZnO by CO at the interface，and that the evaporation rate of Pb is controlled by the volatilization of reduction products, i.e. liquid lead. The overall apparent activation energies of Zn and Pb evaporation from the pellet are 79.42.J/mol and 88.74kJ/mol respectively.

关键词： Zn-Pb-bearing dust carbon-containing pellet evaporation kinetics