We consider the planning and scheduling of production in a multitask/multistage batch manufacturing process typical of industries such as chemical manufacturing, food processing, and oil refining. We allow instances in which multiple sequences of tasks may be used to produce end products. We formulate the problem as a mixed-integer linear program and show that the linear programming relaxation ...

Abstract—Natural gas, as one of the most important sources of energy for many of the industrial and domestic users all over the world, has a complex, huge supply chain which is in need of heavy investments in all the phases of exploration, extraction, production, transportation, storage and distribution. The main purpose of supply chain is to meet customers’ need efficiently and with minimum co...

This note considers an N -stage serial production/inventory system where materials flow from one stage to another in fixed batches. Linear holding and penalty costs (for backorders) are assumed. By Chen [2000], echelon stock (R,nQ) policies are optimal for such systems. Based on the results of Chen [1998], we show that the optimal reorder levels satisfy newsboy inequalities (equalities) when th...

We consider the planning and scheduling of production in a multi-task/multi-stage batch manufacturing process typical of industries such as chemical manufacturing, food processing, and oil refining. We allow instances in which multiple sequences of tasks may be used to produce end products. We formulate the problem as a mixed integer linear program and show that the linear programming relaxatio...

This paper analyses an infinite horizon two-echelon supply chain inventory problem and shows that a sequence of the optimum ordering policies does not yield globally optimal solutions for the overall supply chain. First-order autoregressive demand pattern is assumed and each participant adopts the order-up-to (OUT) policy with a minimum mean square error forecasting scheme to generate replenish...

Mitigating the bullwhip effect is one of crucial problems in supply chain management. In this research, centralized and decentralized model predictive control strategies are applied to control inventory positions and to reduce the bullwhip effect in a benchmark four-echelon supply chain. The supply chain under consideration is described by discrete dynamic models characterized by balance equati...

We consider the classic N -stage serial supply systems with linear costs and stationary random demands. There are deterministic transportation leadtimes between stages, and unsatisfied demands are backlogged. The optimal inventory policy for this system is known to be an echelon base-stock policy, which can be computed through minimizing N nested convex functions recursively. To identify the ke...

77 THIS FEATURE PRESENTS A RELAtively unique concept for urban arterial highway interchanges. The interchange has been named the Echelon Interchange because of its symmetrical, but offset, pair of two-phase one-way pair intersections—one elevated over the other. An observer1 noted that the interchange resembled a flying formation used by the U.S. Navy Flight Demonstration Team, the “Blue Angels...

s-This paper further extends the existing cost model for a fixed-life perishable product in a two-echelon inventory problem into the net profit model. The extended model is subsequently evaluated by comparing its results with those obtained from OptQuest, a commercial simulationoptimization package. Within a limited but reasonable time, the comparative results do not show a significant improvem...