用非线性等温吸附线预测麦圈的货架寿命

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。     

General axisymmetric active earth pressure obtained by the characteristics method based on circumferential geometric condition

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.     

3轴数控机床负角度曲面加工方法

针对国内中小企业多数使用3轴数控机床,并且众多企业都使用UG NX自动编程来实现数控机床自动化,用实际案例阐述了使用UG加工采用3轴数控机床对型腔的负角度加工的方法,利用这些方法能显著提高生产效率,保证加工的表面质量,减少加工成本,缩短生产周期。