Contributed Session Fri.3.MA 042

Friday, 15:15 - 16:45 h, Room: MA 042

Cluster 13: Logistics, traffic, and transportation [...]

Applications of supply chain

 

Chair: Yehua Wei

 

 

Friday, 15:15 - 15:40 h, Room: MA 042, Talk 1

Abolfazl Mirzazadeh
A bi-criteria inventory model under stochastic environment with considering perishable costs

Coauthor: I. Sadeghi

 

Abstract:
A new multiple objectives inventory model has been presented in this paper to determine the optimal production quantity. The deterioration items have been considered and the systems costs will be change over the time horizon. In the real situation, some but not all customers will wait for backlogged items during a shortage period and therefore, the model incorporates partial backlogging. The demand rate can be a function of inflation and time value of money where the inflation and time horizon i.e., period of business, both are random in nature. The objectives of the problem are: (1) Minimization of the total expected present value of costs over time horizon (consists of the deterioration cost, production cost, inventory holding cost, backordering cost, lost sale cost and ordering cost) and (2) Decreasing the total quantity of goods in the warehouse over time horizon. The ideal point approach has been proposed to formulate the model. Also, the numerical example has been provided for evaluation and validation of the theoretical results.

 

 

Friday, 15:45 - 16:10 h, Room: MA 042, Talk 2

Stefan Waldherr
Two-stage order sequence planning in shelf-board production

 

Abstract:
In cooperation with a supplier of kitchen elements the production of storage boards is optimized. Because of the problem's high complexity and the frequent changes of the order situation, the time horizon for the order sequence scheduling should cover at most two days. However, to assure the needed raw material in time for production, it is necessary to determine an approximate schedule outside of the two-day time horizon. Therefore we split the production scheduling into two stages: In a first coarse planning stage we relax the problem by dropping some constraints and consider it as a Min Cost Flow Problem to calculate a production time detailed to the day. This forms the basis for planning the pre-production of the needed raw material to assure their availability. In a second fine planning stage the exact sequence scheduling is carried out taking into account both, resource constraints and sequence-dependent setup- and production times.

 

 

Friday, 16:15 - 16:40 h, Room: MA 042, Talk 3

Yehua Wei
Understanding the performance of the long chain and sparse designs in process flexibility

Coauthor: David Simchi-Levi

 

Abstract:
We study the expected sales of sparse flexibility designs, which are modeled by the expected objective value of a stochastic bipartite max-flow problem. In particular, we focus on the long chain design, a design that has been successfully applied by several industries. First, we uncover an interesting property of the long chain, supermodularity. Then, this property is used to show that the performance of the long chain is characterized by the difference between the expected sales of two simpler designs which leads to the optimality of the long chain among 2-flexibility designs. Finally, under IID demand, this characterization gives rise to three developments: (i) an effective algorithm to compute the expected sales of long chains using only matrix multiplications; (ii) a result that the gap between the fill rate of full flexibility and that of the long chain increases with system size, thus implying that the effectiveness of the long chain relative to full flexibility increases as the number of products decreases; (iii) a risk-pooling result implying that the fill rate of a long chain increases with the number of products, but this increase converges to zero exponentially fast.

 

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