Abstract: The analytical treatment of dissociative diffusion by using the matched perturbation method given in the literature deals with a virtually infinite foreign-atom source producing a constant^concentration at the boundary. In this paper, a new mathematical model is developed for analysing the dissociative diffusion of the solute atoms in the case of finite-source conditions. The mathematical model combines the reaction-diffusion equations which govern solute atom diffusion by the dissociative
mechanism and the boundary condition expressing the fact that the rate at which solute leaves the source is always equal to that at which it enters the sheet over the surface x=0. Solutions obtained by applying the matched perturbation method and their comparison with those of the numerical study are also presented in this paper.

15

Authors: Krzysztof Adamaszek, Zbigniew Jurasz

Abstract: In this paper we give a presentation of the recently developed approaches concerned of
the rate of oxidation the Arema steel at high-temperature in first stage of this process. The
comparison analysis was performed on the basis of the experimental results of oxidation of
cylindrical specimens made of above steel. The experiment was carried out in chamber furnace on
series of specimen with dimension Φ = 20 , l=30 mm. The specimens were oxidized at 1000 °C for
10 - 2280 minutes in air and then quenched in silica sand, afterwards were measured and weighed
both with and without of scale. The analysis reveals that for longer oxidation time than one hour
influence of linear dependence on parabolic growth of scale can be neglected.

237

Authors: Xin Gang Li, Zhen Qing Wang, Nian Chun Lü

Abstract: The dynamic stress field under the SH-waves at the moving crack tip of functionally graded materials is analyzed, and the influences of parameters such as graded parameter, crack velocity, the angle of the incidence and the number of the waves on dynamic stress intensity factor are also studied. Due to the same time factor of scattering wave and incident wave, the scattering model of the crack tip can be constructed by making use of the displacement function of harmonic load in the infinite plane. The dual integral equation of moving crack problem subjected to SH-waves is obtained through Fourier transform with the help of the exponent model of the shear modulus and density, then have some process on the even and odd term of the integral kernel. The displacement is expanded into series form using Jacobi Polynomial, and then the semi-analytic and numerical solutions of dynamic stress intensity factor are derived with Schmidt method.

683

Authors: Chun Sheng Guo, Qian Qian Du, Shi Wei Feng

Abstract: To correct error in theoretical model of process-stress accelerated test, a new calculation method is proposed. The new method, based on computer-aided calculation, can significantly reduce the error of the model. Theoretical data is calculated using both the new model algorithm, which is the root test method, and the old model algorithm. The results show that the old model algorithm can generate error more than 13% in the activation energy and error more than 150% in the extrapolated lifetime (Q≤1.0eV), while the new model algorithm generates error less than 1% in activation energy, and error less than 4.1% in the extrapolated lifetime.

1677

Authors: Wei Jiang, Bin Li, Zhi Bin Feng, Deng Shan Luo, Chuan Fang Yu

Abstract: Cut tobacco was thermodynamics analyzed as infinitesimal volume, and the equation of energy conservation was built. The process of the burn front moving forward for 1 second(s) could be thermodynamics analyzed and another energy equation was also built. Then, the two equations were combined to get the smoldering velocity, which would be added into the mass, momentum, energy equation which was used to describe the whole burning process. The mass, momentum, energy equation was solved by the CFX software, and the results showed that: 1) After a cigarette ignited, the combustion process was accelerated firstly, then the process became slow and at last be at steady state. 2) Paper diffusivity play a critical role in determining the temperature of the smoldering cone, and the results were in good agreement with the experiment results.

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