A Production-inventory Model Variable Lost for Deteriorating Items with Sale Factor

This paper presents an exponential time-varying demand production-inventory mode for deteriorating items with variable lost sale factor and backlogging rates relative to the inventory level and production stages during shortage period. The unique optimal solution is found by Mathematica 5.0. It is proved that service level and deteriorating rate have a greater impact on inventory total cost than demand increasing factor and lost sale factor by sensitivity analysis. The factors must be considered for inventory decision-making of production enterprises.     

EPQ Model with Exponential Time-varying Demand and Different Productivities

Based on the former EPQ models with partial backlogging, this paper develops an EPQ model with exponential time-varying demand and different productivities. The existence of unique optimal solution is discussed by Mathematica 5.0. A numerical example and sensitivity analysis show that the impact of backlogging parameter on all the costs is greater than that of demand increasing factor and productivity during shortage period, and the impact of backlogging parameter on holding cost, shortage cost and opportunity cost due to lost sale is greater than that on setup cost and total cost.     

施肥量对大白菜优质高产的数学模型及其不同地块间的比较

采用３因素二次正交旋转回归设计的方法，研究了大白菜产量与氮、磷、钾施用量的关系，获得了施肥量与产量，纯收益和单株重相互关系的数学模型。对产量形成的３个因子间的主因子效应和交互作用进行了分析。并通过对三块试验地试验结果的比较，提出了正交旋转回归设计方法的适用性。     

Structural Model and Cargo-handling Technology of the Quay with High Amplitude of Water Level in Lantsang

The background of a west communication science & technology project whose topic is structural model and cargo-handling technology of the quay with high amplitude of water level in Lantsang is introduced, and its main research content, research of key technology and main findings are introduced too. Three types of structural model and cargo-handling technology which can be applied perfectly in Lantsang are put forward. The structural models include beam and slab structure with pillar supported, box bridge crane structure and reinforced earth structure, the cargo-handling technologies include vertical fixed crane technology, bridge crane technology and movable simple crane technology. Some findings have been applied in the supporting engineering-Menglun harbor.