基于绩效对比标准的三层生产-分销系统的最优批量策略选择

针对包括生产商、区域配送中心(RDC)和分销商的三层生产-分销系统，考虑货物进出RDC的批量对系 统的影响进行研究。首先利用基于时间基准的最大公约数法优化生产-分销系统模型求得固定批量策略，从而使 供应链上的生产-分销成本最小，在此基础上进一步探讨生产-分销过程中各种可能的情景，得到生产-分销系统 的多重混合批量策略。本文定义了一个绩效对比标准，依据此标准对对固定批量模型和多重混合批量模型进行 求解，得出最优批量决策方案。最后以中石油东北化工销售公司的部分数据作为计算实验和灵敏度分析的来源， 结果验证了绩效对比标准和最优批量模型的有效性。

Researching on the resistance characteristic of the hydraulic excavator

Based on three kinds of digging patterns which been used commonly, the variation regularities of digging resistance with time and digging trajectory in a single digging process were studied. The characteristics of the value of the resistance coefficient and the resistance moment coefficient in different stages of the digging process were obtained using the multiple experimental results. The distribution characteristic of the resistance coefficient and the resistance moment coefficient in both cases that are the resistance is greater than and less than the average resistance were examined in statistics. Based on the variation regularities of direction angles, the impact on resistance by the motion of each component was researched. And then, the distribution characteristics of the resistance angle and the bucket reverse angle in different value range of digging resistance were calculated. This paper studied the resistance characteristic from different perspectives, and obtained the main value range and the probability density of the resistance coefficient, the resistance moment coefficient, the resistance angle and the difference angle. This study laid a foundation for the calculation of theoretical digging force and the design and optimization of excavator working device.