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In gas foil bearings, frictional contacts are one of the main factors that affect bearing performance, which is highly nonlinear. Using a finite element method, this article presents a nonlinear model for static performance analysis of foil bearings based on frictional contacts. The model incorporates the top foil and the interactions between bumps by modeling the foil structure with beam elements. The penalty method and the node-to-segment contact scheme are utilized to model the contacts of the structure. The stick–slip motions of the contact nodes are considered. Because the contact behavior is path dependent when the friction is taken into account, a step-by-step incremental iterative method is used for solution, in which the calculation at the present step is based on the results from the previous step. An algorithm is designed to determine the contact states, and the calculation at the next incremental step will not be performed until all contact states meet the check conditions in the present step. To couple the structure domain with the fluid film, each iterative step of the pressure calculation using the finite difference method is regard as an incremental step. This model is validated by comparisons with published results. Using this model, hysteretic behavior caused by friction and dissipative properties of the foil structure are analyzed under static condition. [ABSTRACT FROM AUTHOR]

The effects of Alcalase and Trypsin hydrolysis on the allergenic protein and its solubility of soybean meal (SBM) were investigated by SDS-PAGE and ELISA. After 10 min of hydrolysis with Alcalase, the solubility of the protein was 87.19%, theα′,αandβ-subunits ofβ-conglycinin disappeared and the acidic and basic subunits of glycinin decreased obviously by SDS-PAGE pattern. However, with Trypsin for 10 min, the solubility of the protein was 72.74%. The contents ofα′,αsubunits ofβ-conglycinin decreased slightly in SDS-PAGE, and the acidic and basic subunits of glycinin were almost not affected. For the insoluble hydrolysates prepared by Alcalase, theα′,αsubunits ofβ-conglycinin and acidic subunit of glycinin decreased significantly, that by trypsin did not. The content of immune-reactiveβ-conglycinin obtained by ELISA was consistent with them. These results confirmed that the allergenic proteins of SBM were more sensitive to Alcalase than to Trypsin. [ABSTRACT FROM PUBLISHER]

Extrusion cooking is a highly efficient food processing technology. During the extrusion process, there are many desirable and undesirable reactions which will determine final product quality. While being heated and sheared simultaneously, food raw materials experience a non-isothermal process and their residence time in the extruder is distributed. All these factors contribute to the difficulties in determining the kinetic parameters for those reactions. Therefore, this paper attempts to review the reaction kinetics in food extrusion. First of all, the kinetic models for the reactions are outlined. After elucidating how to determine reaction time in an extruder, the methodological approaches for determining the reaction order, rate constant, and activation energy of a reaction under isothermal or non-isothermal conditions with or without residence time distribution (RTD) are presented. Then, different models relating the rate constant to its various impact factors, with especially focusing on shear stress, are reviewed. Subsequently, how shear stress is estimated in an extruder, is illustrated. In the last part of this paper, the reported data of rate constant, reaction order, and activation energy for the reactions occurring during food extrusion are summarized, with detailed impacts of temperature, moisture content, shear stress, and determination method on these kinetic parameters. Finally, future research needs are suggested. [ABSTRACT FROM AUTHOR]