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Biomass gasification gains additional significance each year. For the pursuit of the H2 content of product gas, selecting air-dried pine wood chips as gasification feedstock, a lot of experimental work is completed in gasifier by altering the operation parameters such as particle size(60mesh,80mesh,100mesh),temperature (700°C,750°C,800°C,850°C,900°C) and steam mass to biomass mass ratio(S/B)(0.7,1.4,2.1,2.8).The effects of operation parameters on the ingredients of product gas are analyzed, which predicts the optional operation parameters for other biomass gasification.

Aiming at the propagation process of elastic wave in spacecraft stiffener structure. In this paper, the phase and energy changes of elastic waves propagating in the wall structure of stiffeners at different frequencies are analyzed by using finite element method and laser Doppler vibrometer (LDVS). Meanwhile, the relationship between the parameters of stiffeners and the diffusion of acoustic wave energy and the phase change of elastic waves respectively is obtained. The results show that in the range of parameters involved in this paper, the stiffener has a significant effect on elastic waves propagation. When wavelength λ > 10mm, most of the elastic waves are reflected by the stiffener, while when λ < 6mm, elastic waves propagate more easily across the stiffener, and the proportion of those propagated by the stiffener increases. Moreover, the functional expression of the relationship between the height of the stiffener and the frequency of the elastic wave which can easily propagate through the stiffener is obtained.

The phenomenon of gradual decrease of internal stress with the deformation of material maintained under the precondition of certain temperature and initial stress or pre-strain is called stress relaxation. Due to that, the flow stress of the metal material falls rapidly when the hot forming process pauses, and then the required forming load. In this paper, the experiment was carried out to study the stress relaxation property of Ti-6Al-4V, in the temperature range of 1023K~1123K and with the pre-tension strain 0.7%, 4% and 10%. The quartic delay function was used to describe the stress relaxation behavior. The predicted value of stress relaxation equation is in good agreement with the experimental data, and the correlation coefficient is above 0.99. Arrhenius creep constitutive equation embedded in CAE software was derived. The finite element model of stress relaxation process of test bar was builded, and the tensile-relaxation experiment was performed under the loading condition of 1:1 part forming process. The forming force results agree well, and the validity and accuracy of the constitutive model are verified, laying a foundation for the subsequent process simulation and optimization.