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本研究通过对麦圈的非线性等温吸附线的拟合,根据Fick定律,结合包装材料的透湿特性,对包装麦圈在恒温、恒湿保存条件下的水分变化进行了计算机模拟运算。结果表明,理论计算值同实测值吻合得比较好,该模拟运算方法可用于预测各种防潮包装食品储存期间的水分变化。本文还利用模拟运算公式讨论了包装参数及存储环境对货架寿命的影响。 相似文献
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Existing solutions for axisymmetric active earth pressure are based on certain hypotheses of the circumferential stress, lacking of strict basis. This article presents a technique for deriving the actual circumferential stress according to the circumferential geometric condition, the Drucker-Prager criterion and incremental theory. Based on the actual circumferential stress, a new characteristics method for determining the axisymmetric active earth pressure in plastic flow is developed in this article. In this new method, the inclined angle of boundaries, interface friction of contact interface, dilatation effect and flow velocity of soil are considered at the same time. The validity of the new method is confirmed using several sets of experimental data from the literature. The pressure coefficients are investigated individually in detail, and some different conclusions are found. Finally, a practical formula for calculating axisymmetric active earth pressure is presented based on the linear superposition principle, and related tables of coefficients are also provided for engineering application. 相似文献
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