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2002年  第9卷  第2期

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Mineral
Fretting wear of steel wires in hoisting ropes
Dekun Zhang, Shirong Ge, Dangsheng Xiong
2002, 9(2): 81-84.
中文摘要(395) PDF(16) SpringerLink
摘要:
To investigate the fretting wear of steel wires in hoisting ropes, specimens were made of 6×19 point contact ropes. A model for the fretting wear was developed and a fretting wear test rig was deigned in laboratory. A series of experiments were performed on this test rig.The wear volume was taken as a characteristic parameter to describe the fretting wear in relation to the contact load, reciprocating cycles and amplitude. Moreover, the wear mechanisms were discussedin the fretting process.
Metallurgy
Short-range structural change in indium melt by Gaussian peaks decomposing of RDF
Sujuan Cheng, Xiufang Bian, Xubo Qin, Xuemin Pan, Zhonghua Wang
2002, 9(2): 85-89.
中文摘要(256) PDF(13) SpringerLink
摘要:
Liquid indium's structure was studied at 280, 390, 550, 650, and 750℃ Crespectively by using an elevated temperature X-ray diffractometer, and its radial distribution function (RDF) at different temperatures was decomposed into 4 Gaussian peaks in the range of 0.2-0.6nm. Positions of the decomposed Gaussian peaks were compared with the nearest and the second nearest neighbor atomic distances, respectively. It is shown that the position of the first decomposed Gaussian peak is similar to the nearest neighbor atomic distance in liquid In at the corresponding temperature, and that of the third decomposed Gaussian peak is similar to the second nearest neighbor atomic distance. Moreover, the first and the third Gaussian peaks correspond to the first and the second atom shells of liquid In at the corresponding temperatures, respectively.Therefore, the position and the area of Gaussian peaks can represent the position and atom number ofcorresponding shells. Based on this result, short-range structural changes in liquid In was studied. It was found that the first and the second shells are close to the referred atom, and the atom number at the shells decreases with the increasing temperature from 280 to 750℃. In different ranges of temperature, structural changes in the first and the second shells showdifferent features.
Metallurgy
Applicability of mass action law to sulphur distribution between slag melts and liquid iron
Jian Zhang
2002, 9(2): 90-98.
中文摘要(215) PDF(14) SpringerLink
摘要:
According to the mass action law and the coexistence theory of slag structure, the calculating models of mass action concentration for CaO-MgO-FeO-Fe2O3-SiO2,CaO-MgO-MnO-FeO-Fe2O3-P2O5-SiO2 and CaO-MgO-MnO-FeO-Fe2O3-Al2O3-P2O5-SiO2 slag melts are formulated and sulphur distribution between the slag melts and liquid iron is treated. It is found that CaO, MnO and FeO promote desulphurization, while MgO is detrimental to desulphurization. In addition, the sulphur distribution coefficients between the slag melts and liquid iron are presented.
Metallurgy
Surface-particle-emulsion heat transfer model between fluidized bed and horizontal immersed tube
Ping Wu, Li Wang, Xu Feng, Xuezi Ni
2002, 9(2): 99-103.
中文摘要(303) PDF(10) SpringerLink
摘要:
A mathematical model, surface-particle-emulsion heat transfer model, is presented by considering voidage variance in emulsion in the vicinity of an immersed surface. Heat transfer near the surface is treated by dispersed particles touching the surface and through the emulsion when the distance from the surface is greater than the diameter of a particle. A film with an adjustable thickness which separates particles from the surface is not introduced in this model.The coverage ratio of particles on the surface is calculated by a stochastic model of particle packing density on a surface. By comparison of theoretical solutions with experimental data from some references, the mathematical model shows better qualitative and quantitative prediction for local heat transfer coefficients around a horizontal immersed tube in a fluidized bed.
Metallurgy
Similarity solutions to a laminar boundary layer problem in power law fluids
Liancun Zheng, Xinxin Zhang, Fucheng Liao, Jicheng He
2002, 9(2): 104-106.
中文摘要(261) PDF(9) SpringerLink
摘要:
A suitable similarity transformation is introduced to reduce the laminar boundary layer equations of power law fluids to a class of singular nonlinear two-point boundary value problems. The kin friction and shear stress distributions for boundary layer flow over amoving flat plate are investigated by utilizing the shooting technique. Results indicate that for each fixed value of the power law exponent n or the velocity ratio parameter xi, the skin frictionand shear stress decrease with the increasing of n or ξ respectively.
Materials
Effect of dislocation configuration on non-equilibrium boron segregation during cooling
Huaiyang Cui, Bing Cao, Xinlai He
2002, 9(2): 107-113.
中文摘要(271) PDF(10) SpringerLink
摘要:
Different densities and configurations of crystal defects were obtained in an austenitic Fe-30%Ni alloy and an ultra low carbon bainitic (ULCB) alloy by undergoing different deformations and annealing treatments at high temperatures. Boron segregation on grain boundaries and subgrain boundaries during air-cooling were revealed by means of the particle tracking autoradiography technique. It is found that non-equilibrium segregation is resisted indeformed grains after recovery and polygonization, boron-depleted zones seem to be quite clear inrecrystallized grains than those in deformed original grains during cooling. Subgrain boundaries andpolygonized dislocation cells have a significant effect on non-equilibrium boron segregation duringthe air-cooling. The results implicates that dislocation configuration is a more important factor affecting boron segregation at grain boundaries rather that the density of defects itself in thegrain.
Materials
Ultrafine microstructure in microalloyed steel by a new thermomechnical process
Yuanli Wang, Delu Liu, Yonglin Kang, Jie Fu
2002, 9(2): 114-117.
中文摘要(308) PDF(11) SpringerLink
摘要:
Low carbon microalloyed steel containing 0.062% C, 2.34% Mn,0.044% Nb, 0.029% Ti, 0.032% V in mass fraction and small amount of B was prepared in laboratory. Slabs of the steel were rolled into plates of 6mm in thickness followed by accelerated cooling. The plates possess very high yield strength and reasonable ductility, and the yield ratio is about 0.8. Ultra-fine ferrite structure with micrometer dimension was observed in the surface layer of the plates. Moreover, the effect of the finishing rolling temperature on the final microstructure and formation mechanism of ultra-fine ferrite as well as the γ→α transformation behavior of the steel was discussed.
Materials
Growth and microstructure of AlN whiskers and dendrites
Ying Dai, Yue Zhang, Cewen Nan, Mark Hoffman, Mengkui Huang, Jie Li
2002, 9(2): 118-120.
中文摘要(258) PDF(14) SpringerLink
摘要:
AlN whiskers or dendrites were synthesized with asublimation-recrystallization method by using Al, AlN powders and some additives as raw materials.Whiskers with different sizes that featured high purity and good crystallinity were obtained by controlling temperature and gas supersaturation in the reaction container. The whiskers were described as long and straight single crystals of approximately 1-30 μm in diameter by the centimeter range in length. However, AlN dendrites were about 1mm in diameter by 0.5cm in length,and showed an obviously preferential growth orientation, i.e., perpendicular to[2111] and[1011] planes. It is concluded that the whiskers or dendrites grow via the vapor-solidmechanism.
Materials
Fabrication and formation mechanism of NbCx-C three-dimensional netted fibers
Guiying Xu, Jianbao Li, Yong Huang, Shengyou Chai
2002, 9(2): 121-126.
中文摘要(216) PDF(10) SpringerLink
摘要:
Micrometer NbCx-C three-dimensional netted fibers were synthesized by the carbothermal method under 0.1 MPa of N2 ambient atmosphere at a relatively low temperature. Raw materials were commercial powders of Nb2O5 (99.95%), reactive carbon (99.99%), NaCl(99.95%) and sucrose (99.94%). The relationship of the fabrication processing with the composition, crystal structure and morphology of fibers was investigated. The formation mechanism was also proposed and discussed.
Materials
A new acid pickling process for copper alloys
Xing Zou, Bo Song, Keming Fang, Danniang Xu
2002, 9(2): 127-129.
中文摘要(766) PDF(63) SpringerLink
摘要:
The cleaning process of removing oxides on the surface of copper alloy sheets was investigated systematically. Through optimizing, a perfect process was selected that is fit for removing oxides on the surface. By acid pickling, all kinds of copper oxides are removed completely, furthermore, no poisonous gases are given out and a smooth and clean surface of copper alloys is obtained. At present, the process is applied successfully in the copper-processing industry.
Materials
Effect of hydrogen attack on acoustic emission behavior of low carbon steel
Xiaogang Li, Chaofang Dong, Ming Li, Hua Chen
2002, 9(2): 130-134.
中文摘要(243) PDF(9) SpringerLink
摘要:
In order to investigate the effect of hydrogen attack degree on acoustic emission(AE) behavior of low carbon steel during tensiling, specimens made of Low carbon steel was exposed to hydrogen gas of 18 MPa at 450 and 500℃ for 240, 480 and 720 h respectively. Experimental results show that with increase of the hydrogen attack degree, the totally AE activity decreases during tensiling. In addition, the count of AE signals with high amplitude for the specimens with hydrogen attack keeps a constant which is less than that without hydrogen attack. It is concluded that AE signals originate in the specimens with hydrogen attack from intergranular fracture induced by methane blisterings or/and microcracks on grain boundaries.
Materials
Plastic equation of state determined by nano indentation
Yanli Wang, Zhi Lin, Junpin Lin, Guoliang Chen
2002, 9(2): 135-137.
中文摘要(227) PDF(9) SpringerLink
摘要:
In order to characterize the plastic state of a deformed material, an indentation method to determine the plastic equation of state(PES) was developed. The work-hardening coefficient and the strain rate sensitivity coefficient of the plastic mechanic equation of state were determined by two kinds of indentation tests respectively. Therefore, the PES of materials under deformation can be obtained, and the plastic state of materials can be determined.
Materials
Contact position controlling for two-dimensional motion bodies by the boundary element method
Junping Pu, Yuanfeng Wang
2002, 9(2): 138-144.
中文摘要(231) PDF(9) SpringerLink
摘要:
An algorithm is presented for controlling two-dimensional motion contact bodies with conforming discretization. Since a kind of special boundary element is utilized in the algorithm, the displacement compatibility and traction equilibrium conditions at nodes can be satisfied simultaneously in arbitrary locations of the contact interface. In addition, a method is also proposed in which the contact boundary location can be moved flexibly on the possible contact boundary. This method is effective to deal with moving and rolling contact problems on a possible larger moving or rolling contact region. Numerical examples show effectiveness of the presented scheme.
Information
Fuzzy optimization of space frame
Zaigen Mu, Zhe Wu, Long Xiu
2002, 9(2): 145-148.
中文摘要(213) PDF(9) SpringerLink
摘要:
Fuzzy concepts are introduced into structural optimization to solve fuzzy optimization problems with a crisp objective function and fuzzy constraints, also a non-membership function is used to convert fuzzy constrains into crisp constrains. Two models are discussed where the objective function considered is the volume of space frame and the fuzzy constrains are design limits by the axial strength, slenderness, deflection, thickness and diameter of space frame member.
Information
Robust exponential control of a class of systems with uncertainties
Fucheng Liao, Tohru KATAYAMA, Liancun Zheng
2002, 9(2): 149-155.
中文摘要(215) PDF(8) SpringerLink
摘要:
The robust exponential stabilization problem for uncertain systems isstudied. Based on the solution for a nominal linear quadratic regulator problem with a prescribed degree of stability, the methods of constructing state feedback controllers are developed to ensure the robust stability of the closed loop system under the conditions weaker than the matching condition. Also, the cases where the matching condition is satisfied are considered in detail. Some examples are included to show the solution methods.
Information
An architecture for mobile database management system
Dong Li, Yucai Feng
2002, 9(2): 156-160.
中文摘要(313) PDF(13) SpringerLink
摘要:
In order to design a new kind of mobile database management system (DBMS)more suitable for mobile computing than the existent DBMS, the essence of database systems in mobile computing is analyzed. An opinion is introduced that the mobile database is a kind of dynamic distributed database, and the concept of virtual servers to translate the clients' mobility to the servers' mobility is proposed. Based on these opinions, a kind of architecture of mobile DBMS, which is of versatility, is presented. The architecture is composed of a virtual server and a local DBMS,the virtual server is the kernel of the architecture and its functions are described. Eventually,the server kernel of a mobile DBMS prototype is illustrated.

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