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Based on the log data generated in the “Engineering Mechanics Experiment” Autonomous Learning Platform designed and developed by our institution, firstly the related data of students' landing behavior and resources explored behavior are collected and pretreated. And then the feature of the students' study behavior are analyzed, based on the analysis the factors that affect the students' log in and resources explore behavior are acquired by the decision tree algorithm. According to the analysis the education workers can adjust and optimize the teaching strategies, improve the teaching process and the curriculum development, and then to organize the teaching content and build teaching mode according to the student's study behavior.

Based on the basic fact that the glass transition is a physical phenomenon which occurs in nonequilibrium solidification conditions, the dynamical process of rapid solidification is discussed by using nonlinear theory and a bifurcation theory model for the glass transition is established. It is shown that in rapid solidification a multiple steady states phenomenon can take place because of the serious nonequilibrium of the solidification condition and the nonlinear coupling between the solidification rate and the solidification temperature, and this multiple steady states phenomenon can be understood as the glass transition. Then, the thermodynamic behavior of the rapid solidification process is analyzed by using nonequilibrium thermodynamics, and this thermodynamic analysis shows the possibility of the solidification system becoming unstable when the solidification system is far from the equilibrium solidification point to some extent because of the rapid solidification condition. This model can explain some experimental features of the glass transition such as the changes of specific heat Cp, expansion coefficient α, diffusion constant D, and viscosity η and the cooling rate dependence of Tg. And also, the critical cooling rates of forming glass and the reduced glass transition temperatures of some alloys estimated by this model are consistent with the experimental results.

To avoid the instability of small parts welding, the paper proposes a new type of spot welding inverter, mainly controlled by digital signal processor(DSP) dsPic30F6010A. The system enables stable constant current through fuzzy control. The paper introduces the component , principle and design of the system in details. The experimental result shows that the fluctuation ratio of output current under different service voltage and load conditions is 2% by using the fuzzy control designed.

The Raman cross-sections of β-carotene C=C double bond （1520 cm－1） and C—C single bond（1155 cm－1） vibration mode have been measured using cyclohexane as internal standard. The result shows that the Raman cross-section of β-carotene increases with the increase of refractive indexes of solvents. The difference of β-carotene Raman cross-section in different refractive indexes of solvents was explained by the dispersion and resonance Raman theory.

The Raman spectra of CS 2 in C 6 H 6 is messured and the Fermi resonance of v 1 —2 v 2 in solution and in pure CS 2 is obvionsly different.The characteristic parameters are calculated by Berttern equation.It was found that with the concentration of CS 2 declining,the ratio of the spectral intensity （ R = Ｉ 655 / I 796 ） decreases and the coupling coefficient （ Ｗ ） raises, and the other parameters also change correspondingly. The analysis shows that dissipation coefficient of v 0 1 of CS 2 is affected by the concentration of C 6 H 6 . Asymmetric frequency shift of v 0 1 and 2 v 0 2 are observed in experiment,which is explained by amending the Bertran theory. This report has reference value for the molecule spectrum certification and the understanding and use of Fermi resonance theory.

Based on the approximate entropy theory and related algorithm, approximate entropy analysis of current in short-circuiting arc welding in CO2 shielding gas are performed from the point of view of nonlinear time sequences. Calculation and comparison of approximate entropy of current under different wire-feeding speeds, setting voltages and different gas flow rates show that approximate entropy of current can be taken as a creterion of stability of short-circuiting transfer. The results show that greater approximate entropy and less fluctuation indicate a more stable welding process.