Improvement of Temperature Uniformity of Instant Rice Inside Plastic Rectangular Container Under Microwave Reheating

To improve the temperature uniformity of instant rice in a plastic rectangular container, during microwave reheating, the changes of temperature distribution were analyzed by using experiment and simulation method. A three-dimensional finite element model was established to describe microwave reheating of instant rice to predict the temperature. The results showed that the highest temperature occurred at the corners and bottom layer. The cold spots were located in the sample interior center. The simulation results in the model matched relatively with the experimental results. A method of intermittent microwave reheating was proposed to improve the temperature uniformity of convenient rice, and the optimal combination was the time of microwave reheating was 180 s, and the intermittent ratio was 1 : 3.

工业化阶段演进中加工贸易对经济增长集约化水平的非线性效应——基于平滑转移的阈值协整模型检验

加工贸易的逆“自我选择”效应及税收优惠政策扭曲资源配置可能阻碍经济增长集约化水平提升;但是随工业化阶段的演进,加工贸易通过多条途径促进经济增长集约化水平提升,进而部分抵消加工贸易对经济增长集约化水平的负向作用,即加工贸易对经济增长集约化水平的影响可能发生非线性变化。文章利用我国1981~2017年数据并构建阈值协整模型检验发现:加工贸易对经济增长集约化水平具有负向作用;随工业化阶段演进即第二产业产值与第三产业之比低于某一数值时,加工贸易的负向作用减弱;采用不同方法测度部分变量,加工贸易对经济增长集约化水平均存在非线性效应,实证检验结果是稳健的。上述研究表明,随着工业化阶段演进,加工贸易发展的专业化分工效应、规模经济效应等不断凸显,促进经济增长集约化水平提升,减弱了加工贸易对经济增长集约化水平的负向作用。