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Theoretical analysis of alloy multiplying factor by the empirical electron theory of solids and molecules

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Science china(Technological Sciences) 2007年第6期50卷 807-814页

作者： SONG YuePeng1,2, LIU GuoQuan2, LI ZhiLin3, FENG ChengMing1 1 Mechanical and Electronic engineering College, Shandong Agricultural University, Tai’an 271018, china 2 College of Materials Science and engineering, University of Science and Technology, beijing 100083, china 3 College of Material Science and engineering, beijing University of Chemical Technology, beijing 100029, china Mechanical Electronic engineering College Shandong Agricultural University Tai’an 271018 China College of Materials Science engineering University of Science Technology Beijing 100083 China College of Material Science engineering Beijing University of Chemical Technology Beijing 100029 China

By introducing the distribution probability of structural units in austenite contain- ing alloying elements and considering its effects on phase transformation, this paper establishes a calculation model of distribution probability of structural units. A new valence electron structure (VES) parameter-transformation effect coefficient of alloying elements (HL), is defined and then studied both theoretically and ex- perimentally. The relationship between the parameter HL and the multiplying factor (the quenching capability factor) of alloying elements is studied. The results indi- cate that the two parameters (HL and the quenching capability factor) have the same variation characteristic and substance feature. Therefore, the multiplying factor virtually expresses the relative quantity of structural units in the alloying elements-containing austenite.

关键词： multiplying factor (the quenching capability factor), empirical electron theory of solids and molecules, transformation effect coefficient of alloying elements, structural units in austenite containing alloying elements

Producing Calcium-Bearing Mullite Thermal-Insulating Refractories by Kyanite

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International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 50-53页

作者： Wen Ni (Resources engineering School, University of Science and Technology beijing, beijing 100083, china) Resources engineering School University of Science and Technology Beijing Beijing 100083 China

To improve the physical properties, a series of experiments have been camed out to produce calcium-bearing mullite thermal-insulating refractories by using kyanite as major raw materials. The experiments were carried out by a foaming technique and using white cement as a combing agent. The results show that the calcium-bearing mullite refractory has much better physical properhes than traditional clay refractory and high-alumina refractory.

关键词： mullite thermal-insulating refractory kyanite

The mathematical model of wetting angle of heterogeneous nucleation

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Science china(Technological Sciences) 2004年第4期47卷 391-397页

作者： HUANG Cheng1, SONG Bo1, MAO Jinghong2 & ZHAO Pei3 1. School of Metallurgical and Ecological engineering, University of Science and Technology beijing, beijing 100083, china 2. School of Material Science, University of Science and Technology beijing, beijing 100083, china 3. Central Iron and Steel Research institute, beijing 100081, china 1. School of Metallurgical and Ecological engineering University of Science and Technology Beijing 100083 Beijing China 2. School of Material Science University of Science and Technology Beijing 100083 Beijing China 3. Central Iron and Steel Research institute 100081 Beijing China

The heterogeneous nucleation has been analyzed in terms of the thermodynamic theory, and the mathematical model of wetting angle of heterogeneous nucleation has been developed based on the dynamic requirements of hetero- and homogeneous nucleation. With the wetting angel model, the wetting angles of different catalysts in liquid iron have been calculated. The result shows that the wetting angle of most catalysts is smaller than 40, and the value of f() is far less than 1. The wetting angles of TiN, TiC and RE2O3 are smaller, while the wetting angle of MnO is bigger among the ordinary nucleation catalysts. The wetting angles calculated by this model are in agreement with the results of other research work.

关键词： heterogeneous nucleation, mathematical model, wetting angle, undercooling.

Effects of Cobalt on the Sintering Behavior of Mechanically Activated Tungsten Powder

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Rare Metals 2001年第3期20卷 183-186页

作者： Chengchang Jia, Xiaoyang Liu, Xiuhu Guan, Xuekuan Su, Jun Zhao, Zizhang Xie 1) Materials Science and engineering School, University of Science and Technology beijing, beijing 100083, china 2) beijing Research institute of Powder Metallutrgy, beijing 10005 Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China beijing Res Inst Powder Met Beijing 100053 Peoples R China beijing Polytech Univ Beijing 100022 Peoples R China

Tungsten alloys were prepared with mechanically activated powder added microelement cobalt in order to improve the process and properties of alloys. Properties of alloys such as density, hardness and bending strength were measured. The results show that through mechanical activation, cobalt can accelerate the sintering process of these alloys By the combination of mechanical activation and adding microelement cobalt, tungsten alloys with higher density and better properties can be obtained.

关键词： powder metallurgy tungsten alloys cobalt mechanical activation sintering behavior

ITERATION SOLUTION OF THE MIXED FORMULATION IN NONLINEAR FEM

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Chinese Journal of Aeronautics 1996年第4期9卷 261-268页

作者： Wang Shoumei(beijing University of Aeronautics and astronautics, beijing, china, 100083) beijing Univ. Aero. and Astronaut. Beijing 100083 China

Various mixed formulations of the finite element method (FEM) yield matrix equations involving zero diagonal entries. They are then dealt with by a penaltymethod so that they become non-zero but near zero terms. However, the penalty has tobe chosen properly. If it is too large, the matrix equation may become ill-conditioned. Onthe other hand, the matrix equation may give incorrect answer if the penalty is too *** non-linear regime, the difficulty is more serious because the magnitude order of the matrix varies considerably in the entire loading history. The paper suggests an iteration solution and applies it to non-linear FEM of rubber-like hyper-elasticity. This type of analysisis highly non-linear both in physics and in geometry as well as the strong constraint of incompressibility. The iteration solution is demonstrated to possess super precision and excellent convergence characteristics.

关键词： iteration solution nonlinearity finite element method penalty function,hyper-elasticity

Effect and mechanism of stresses on rock permeability at different scales

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Science china Earth Sciences 2006年第7期49卷 714-723页

作者： YIN Shangxian1 & WANG Shangxu2 1. Safety engineering College, North china institute of Science and Technology, Yanjiao, beijing 101601, china 2. Key Laboratory of Geophysics Exploration, china University of Petroleum, beijing 100083, china 1. Safety engineering College North China Institute of Science and Technology Yanjiao Beijing 101601 China 2. Key Laboratory of Geophysics Exploration China University of Petroleum Beijing 100083 China

The effect of geo-stress fields on macroscopic hydro-geological conditions or micro-cosmic permeability of water-bearing media should follow some laws or principles. Cases study and tests show that: (1) At macro-geologic large scale, deformed and crashed rocks which were induced by geo-stress fields changing provided space for groundwater storage and flow. Groundwater adjusts water-bearing space and dilatants fractures by flowing and press transferring. Coupling of liquid and solid can be implemented for rocks and groundwater. Although tectonic fields witness several times of change and build-up in geological time, stress fields forming regional tectonic framework are coherent with seepage fields, orientation of the maximum horizontal stress demonstrates main seepage direc-tions. (2) At macro-geologic middle scale, zones of stresses changing sharply, quite low stresses, stress or shear concentration can be used to show locations and types of main fractures, zones of geo-stresses changing equably can be acted as normal base media zones of tri-porosity media. (3) At micro-geologic small scale, tri-porosity media include fractured rocks, porous rocks and capillary rocks. Investigations indicate that porosity or permeability is functions of effective stresses, and po-rosity or permeability changing rules of porous rocks with variation of effective stresses can be de-scribed as the index model, the model of power exponent functions is suitable for those of fractured rocks, the model of the second power parabola for capillary rocks. The porosity and permeability loss in fractured rocks, which are greater than that in porous rocks, are shown by calculation of effective compressive coefficient and closing pressure in cracks. The calculations can also explain the mecha-nism why porosity changes are always larger than permeability changes. It is proved by the thick wall cylinder theory that the second power parabola relation between porosity or permeability loss and effective

关键词： geo-stress fields, seepage fields, tri-porosity media, effective stresses, permeability, porosity,scale.

Target selection and transfer trajectories design for exploring asteroid mission

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Science china(Technological Sciences) 2010年第4期53卷 1150-1158页

作者： CUI PingYuan1,QIAO Dong1,CUI HuTao2 & LUAN EnJie3 1 School of Aerospace engineering,beijing institute of Technology,beijing 100081,china 2 Harbin institute of Technology,Harbin 150001,china 3 National Defense Science and Industry Bureau,beijing 100048,china 1. School of Aerospace engineering Beijing Institute of Technology Beijing 100081 China2. Harbin Institute of Technology Harbin 150001 China3. National Defense Science and Industry Bureau Beijing 100048 China

Technique of target selection and profiles of transfer trajectory for Chinese asteroid exploring mission are studied systemically.A complete set of approaches to selecting mission targets and designing the transfer trajectory is ***,when selecting a target for mission,some factors regarded as the scientific motivations are ***,when analyzing the accessibility of targets,instead of the classical strategy,the multiple gravity-assist strategy is *** suitable and possible targets,taking into account scientific value and technically feasible,are obtained via selection and *** designing the transfer trajectory for exploring asteroid mission,an approach to selecting gravity-assist celestial body is ***,according to the mission constraints,the trajectory profile with 2-years △V-EGA for exploring asteroid is *** analyzing the trajectory profile,unexpected result that the trajectory would pass by two main-belts asteroids is ***,the original proposal is extended to the multiple flybys *** adds the scientific return for asteroid mission.

关键词： exploring asteroid target selection multiple flybys transfer trajectory

Modeling and characteristic analysis of underwater acoustic signal of the accelerating propeller

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Science china(Information Sciences) 2012年第2期55卷 270-280页

作者： FENG Yuan1,2,TAO Ran1 & WANG Yue11Department of Electronic engineering,beijing institute of Technology,beijing 100081,china 2Science Research institute of china North Industries Group Corporation,beijing 100081,china 1. Department of Electronic engineering Beijing Institute of Technology Beijing 100081 China2. Science Research Institute of China North Industries Group Corporation Beijing 100081 China

The signal feature of propeller cavitation noise during acceleration or deceleration procedure can be used to passively detect and classify moving vessels and underwater vehicles in the port *** analyzing the chirp periodicity of the variation of propeller wake velocity under acceleration situation,this paper presents a time domain expression of the modulation envelope signal of the accelerating propeller noise,treating the signal as a Gaussian-shaped chirp periodic pulse train with increasing trend and fluctuating pulse *** paper investigates the characteristics of simplified fractional Fourier transform(SFRFT)spectrum of the chirp periodic signal,and thus obtains the relation between the chirp periodic signal and its chirp harmonics under the conditions of underwater passive ***,the experimental data of the cavitation tunnel satisfy the results obtained by simulation,which verifies the correctness of the proposed signal model.

关键词： accelerating propeller modeling of underwater acoustic signal chirp periodic signal simplified fractional Fourier transform

Theoretical analysis of polarization properties for tilted fiber Bragg gratings

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Science china(Information Sciences) 2010年第2期53卷 390-397页

作者： XU Ou 1 , LU ShaoHua 2 & JIAN ShuiSheng 2 1 Faculty of Information engineering, Guangdong University of Technology, Guangzhou 510006, china 2 institute of Lightwave Technology, beijing Jiaotong University, beijing 100044, china 1. Faculty of Information engineering Guangdong University of Technology Guangzhou 510006 China2. Institute of Lightwave Technology Beijing Jiaotong University Beijing 100044 China

The polarization properties for tilted fiber Bragg gratings (TFBGs) are investigated theoretically based on coupled-mode theory and Mueller matrix method. The expression of wavelength-related polarizationdependent loss (PDL) for TFBGs with different tilt angles is derived and calculated. Simulation results are compared, and the results indicate that the polarization capability of TFBGs with 45° angle is stronger than other TFBGs with smaller angles. The degree of polarization for unpolarized light passing TFBGs is also simulated to further evaluate the polarization properties for various tilt angles. In addition, the relationship between physical parameters of a TFBG and its polarization capability is discussed.

关键词： coupled-mode theory degree of polarization (DOP) Mueller matrix method polarization dependent loss (PDL) tilted fiber Bragg gratings