MENDED GENETIC BP NETWORK AND APPLICATION TO ROLLING FORCE PREDICTION OF 4-STAND TANDEM COLD STRIP MILL

In order to make good use of the ability to approach any function of BP (backpropagation) network and overcome its local astringency, and also make good use of the overallsearch ability of GA (genetic algorithms), a proposal to regulate the network's weights using bothGA and BP algorithms is suggested. An integrated network system of MGA (mended genetic algorithms)and BP algorithms has been established. The MGA-BP network's functions consist of optimizing GAperformance parameters, the network's structural parameters, performance parameters, and regulatingthe network's weights using both GA and BP algorithms. Rolling forces of 4-stand tandem cold stripmill are predicted by the MGA-BP network, and good results are obtained.

Analysis and Prediction of Sintering Behavior of Diphase Sialon and Diphase β—Sialon／Alumina Composites by Artificial Neural Network

In this paper,the sintering behavior of diphase β-Sialon and Al2O3/diphase β-Sialon composites has been studied and predicted by using ANN (Artificial Neural Network) method.It is found that relative density is well correlated with phase composition and sintering temperature and that the predicted values by this method are very clos to experimental results.Effectiveness of modeling has been discussed nd analyzed by presenting formulas, This may be the first attempt of applying ANN mthod in the study of refractories science and has indicated that ANN is an efficeint method.

Mechanism of a-Cr Formation in Nickel-Base Superalloy INCONE1718 after Long Time Thermal Exposure

It is commonly accepted that the drop in mechanical properties of INCONE1718(IN718) after long time exposure at high temperature is a result of coalescence of y", ?/ and the transformation of y" to 8-Ni3Nb phase. Besides the 7", ?/ and , the precipitation of B.C.C. -Cr is another factor that affects the mechanical properties of IN718. In this paper, the Thermal-Calc software is used to reveal the thermodynamic condition of -Cr formation. The calculated sections of the pseudo ternary diagrams of Cr-Nb-IN718 and Cr-Fe-IN718 explain why -Cr particles do not precipitate dispersedly in matrix but in the vicinity of phase. The selected area diffraction (SAD) of TEM confirms the crystallography relationship of -Crwith is (010) g// (-110) a.Cr, [100] s//[Hl] a-cr? In combination of TTT diagram with the Thermal-Calc and TEM results, the mechanism of -Cr formation in IN718 is suggested.

Anisotropic plastic deformation behavior of B2-ordered Fe_3Al single crystals at room temperature

The tensile plastic deformation behavior of B2 ordered Fe 3Al single crystals at room temperature was systematically investigated. The results show that the mechanical properties are strongly orientation dependent. The plastic elongation of crystals with orientation near is as high as 42%. Slip trace analysis shows that although slip planes are found to change among {110} , {112} and {123} with the change in orientations, the initial slip planes in all cases are {110}. Five stage work hardening curve including four linear stages and one parabolic stage is obtained; but not all stages are observed in the actual deformation of each crystal. In combination with investigations of dislocation substructure, it is found that deformations in stage Ⅰ～Ⅲ are corresponding to the motion of two fold superdislocations. The higher work hardening rate of stage Ⅱ is mainly due to the stronger interactions between primary dislocations and secondary dislocations than those in stage Ⅲ. Deformation in stage Ⅳ involved is not only the motion of two fold superdislocations but also the slip of dissociated superpartials with APB traps and the formation of APB tube, both of which are attributed to the hardening. Deformation in stage Ⅴ is controlled by the cross slip of dissociated superpartials. The dominated softening effect of cross slip reduces the hardening rate and leads to the formation of parabolic stage.

Atomic scale KMC simulation of {100} oriented CVD diamond film growth under low substrate temperature-Part Ⅱ Simulation of CVD diamond film growth in C-H system and in Cl-containing systems

The growth of {100}-oriented CVD diamond film under two modifications ofJ-B-H model at low substrate temperatures was simulated by using a revised KMC method at atomicscale. The results were compared both in Cl-containing systems and in C-H system as follows: (1)Substrate temperature can produce an important effect both on film deposition rate and on surfaceroughness; (2) Aomic Cl takes an active role for the growth of diamond film at low temperatures; (3){100}-oriented diamond film cannot deposit under single carbon insertion mechanism, which disagreeswith the predictions before; (4) The explanation of the exact role of atomic Cl is not provided inthe simulation results.

Short Notes ON THE γ—ε TRANSFORMATION BELOW THE NEEL TEMPERATURE IN Fe—Mn—Si ALLOYS

There are two tpyes of phase transformations in Fe-Mn and Fe-Mn-Si alloys when the temperature is decreased,γ(fcc)→ε(hcp) martensitic transformation(MT) and paramagnetic-antiferromagnetic transition (AMT) of γ phase.From the thermodynamic point of view,the former usually appears in a slightly higher temperature range than the latter because if is generally accepted that the magnetic tansition has a suppressing effect on the thermally induced ε martensite(Sato et al.,1984.,Bogachev and Zvigintzeva,1976;Murakami et al.,1987:Yang et al.,1992) Gartstein and Robinkin(1979) even thought that the γ-ε transformation should be terminated below Neel temperature(TN) due to the decrease of free energy arising from the AMT of γ phase.However,some experimental results hae indicated the formation of ε phase below T(Li and Wayman,1994:Fujimori.1966).In the present wert.the behavor of γ-ε transformation below TN was furtherinvestigated by clectrical resistance measurements.

Thermal Conductivity Measurement of Semitransparent Media at Temperatures from 300 to 800 K by Hot－Wire Method

In this paper,a new measurement technique for determining thermal conductivity of semitransparent media in the temperature range 300-800 K is reported.The experimental setup is based on the step power forced transient hot wire technique.It is assumed that the radiative contribution to the heat transfer process arises from emission,not from absorption.In this case,application of the'thermal quadruples'method allows a very simple construction of analytical models of the experimental setup.The parameter sensitivity analysis demonstrates that the thermal conductivity of semitransparent media can be determined from the hot wire temperature response. The experimental results of a kind of glass between 300 and 800 K are presented.