Integrated Inventory Models With An Uncertain Environment

With the development of world economic integration and marketglobalization, and the speed-up of the information technology, scientificproduction planning and inventory control has become an important issue for themodern enterprises. It is also the academic focus now. In this thesis, someinventory models with an uncertain environment are studied.The main contents are as follows:In Chapter 1, we firstly introduce the modes of inventory control in supplychain and the effects of uncertain factors on inventory. Then, the recent researchon inventory models in supply chain is briefly reviewed, and the main results ofthe thesis are summarized.In Chapter 2, we consider the problem of purchase, production andinventory for a system with single vendor and single buyer. An integratedstochastic inventory model is proposed in which the order quantity, the reorderpoint, the length of the lead time and the number of shipments are treated asdecision variables. Moreover, an iterative procedure is developed to seek theoptimal solution and numerical examples are given to illustrate the validity of the model and algorithm.In Chapter 3, the problem of economic manufacturing quantity and the saleprice in an unreliable production system is considered, where the machinelifetime is subject to exponential distribution and the failure rate of the machinedepends on the production rate. A profit model is formulated in whichproduction uptime, production rate and sale price are treated as decisionvariables. Then, under some proper conditions, we show that the objectivefunction is unimodal and propose formulas to compute the up bound and lowbound of production uptime. Finally, numerical examplesare given to illustratethe Validity of the model, and the sensitivity analysis is also performed.In Chapter 4, an integrated inventory model with a deteriorating productionprocess is proposed. For a system with single-vendor and multi-buyer, weassume that the. production system consists of one production unit which has akey module that .deteriorates over time. The time when a key module-shifts fromthe in-control status to the out-of-control status is subject to exponentialdistribution and some percentage of the items produced are defective once thekey module is in the out-of-control status. A cost model is formulated in whichthe number of standbys, the production run length and the number of shipmentsare treated as decision variables. To find the optimal solution, a real-codedgenetic algorithm is developed.Finally, the research work is summarized, and some suggestions about theresearch on integrated inventory model are made.