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1
Content available Explicit modeling of multi-period setup times in proportional lot-sizing and scheduling problem with variable capacity
Kaczmarczyk Waldemar
Archives of Control Sciences
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2021
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Vol. 31, No. 4
883--912
EN
Small bucket models with many short fictitious micro-periods ensure high-quality schedules in multi-level systems, i.e., with multiple stages or dependent demand. In such models, setup times longer than a single period are, however, more likely. This paper presents new mixed-integer programming models for the proportional lot-sizing and scheduling problem (PLSP) with setup operations overlapping multiple periods with variable capacity. A new model is proposed that explicitly determines periods overlapped by each setup operation and the time spent on setup execution during each period. The model assumes that most periods have the same length; however, a few of them are shorter, and the time interval determined by two consecutive shorter periods is always longer than a single setup operation. The computational experiments show that the new model requires a significantly smaller computation effort than known models.
2
Content available Joint effect of forecasting and lot-sizing method on cost minimization objective of a manufacturer: a case study
Olesen Jack, Pedersen Carl-Emil Houmøller, Knudsen Markus Germann, Toft Sandra, Nedbailo Vladimir, Prisak Johan, Nielsen Izabela Ewa, Saha Subrata
Applied Computer Science
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2020
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Vol. 16, no 4
21--36
EN
Forecasting and lot-sizing problems are key for a variety of products manufactured in a plant of finite capacity. The plant manager needs to put special emphasis on the way of selecting the right forecasting methods with a higher level of accuracy and to conduct procurement planning based on specific lot-sizing methods and associated rolling horizon. The study is con-ducted using real case data form the Fibertex Personal Care, and has evalu-ated the joint influence of forecasting procedures such as ARIMA, exponen-tial smoothing methods; and deterministic lot-sizing methods such as the Wagner-Whitin method, modified Silver-Meal heuristic to draw insights on the effect of the appropriate method selection on minimization of operational cost. The objective is to explore their joint effect on the cost minimization goal. It is found that a proficient selection process has a considerable impact on performance. The proposed method can help a manager to save substantial operational costs.
3
Content available remote A Batching Machine Model for Lot Scheduling on a Single Machine
Kovalyov M. Y.
Foundations of Computing and Decision Sciences
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2018
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Vol. 43, No. 1
38--40
EN
A recently introduced lot scheduling problem is considered. It is to find a partition of jobs of n orders into lots and to sequence these lots on a single machine so that the total average completion time of the orders is minimized. A simple O(n log n) time algorithm is presented for this problem in the literature, with a relatively sophisticated proof of its optimality. We show that modeling this problem as a classic batching machine problem makes its optimal solution obvious.
4
Content available Exponential smoothing for multi-product lot-sizing with heijunka and varying demand
Korytkowski P., Grimaud F., Dolgui A.
Management and Production Engineering Review
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2014
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Vol. 5, No. 2
20--26
EN
Here we discuss a multi-product lot-sizing problem for a job shop controlled with a heijunka box. Demand is considered as a random variable with constant variation which must be absorbed somehow by the manufacturing system, either by increased inventory or by flexibility in the production. When a heijunka concept (production leveling) is used, fluctuations in customer orders are not transferred directly to the manufacturing system allowing for a smoother production and better production capacity utilization. The problem rather is to determine a tradeoff between the variability in the production line capacity requirement and the inventory level.
5
Content available Cooperative Games in Integration of Supply Chain on the Example of Purchasing Groups
Rzeczycki A.
Logistics and Transport
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2014
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Vol. 24, No. 4
15--20
EN
Purchasing group can improve the chance of a higher return for individual entities in the supply chain. The greater sales occurs between companies, the higher the probability of deepening integration between them. Functioning of the purchasing group is, however, dependent on the justice of imputation the profits generated by it (discounts, cost reduction) for its entities. Article presents the use of cooperative game, in order to explain the possibility of optimizing and sharing the profits (payoffs), and in a longer perspective, build an integrated supply chain.
6
Content available Extended model formulation of the Proportional Lot-sizing and Scheduling Problem with lost demand costs
Kaczmarczyk W.
Decision Making in Manufacturing and Services
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2011
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Vol. 5, no. 1-2
49-56
EN
We consider mixed-integer linear programming (MIP) models of production planning problems known as the small bucket lot-sizing and scheduling problems. We present an application of a class of valid inequalities to the case with lost demand (stock-out) costs. Presented results of numerical experiments made for the the Proportional Lot-sizing and Scheduling Problem (PLSP) confirm benefits of such extended model formulation.
7
Content available Partial coordination may increase overall costs in supply chains
Kaczmarczyk W.
Decision Making in Manufacturing and Services
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2008
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Vol. 2, no. 1-2
47-62
EN
This paper presents a computational study to evaluate the impact of coordinating production and distribution planning in a two-level industrial supply chain. Three planning methods are compared. The first emulates the traditional way of planning. The two other coordinate plans of the supplier and of all the buyers according to the Vendor Managed Inventory (VMI) approach. The monolithic method solves a single model describing the entire optimization problem. The sequential method copies the imperfect VMI practice. All three methods are implemented by means of Mixed Integer Programming models. The results presented prove that the right choice of planning method is very important for overall cost of the supply chain. In contrast to the previous research, it turned out that information sharing without full coordination may even lead to increase in the overall cost. For some companies applying the VMI approach, developing exact models and solving them almost optimally may therefore be very important.
8
Modele PLC planowania wielkości i szeregowania partii z identycznymi liniami równoległymi
Kaczmarczyk W.
Zeszyty Naukowe. Automatyka / Politechnika Śląska
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2006
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z. 144
23-32
PL
Praca opisuje modele programowania całkowitoliczbowego mieszanego zadań planowania wielkości i szeregowania partii wielu produktów na identycznych liniach produkcyjnych o ograniczonej wydajności. Dla przypadku, gdy w jednym okresie mogą być produkowane dwa produkty, zaproponowany został nowy model ze zmiennymi całkowitoliczbowymi, opisującymi liczbę maszyn przezbrojonych do wykonywania danego wyrobu.
EN
This paper addresses mixed integer programming models of the lot-sizing and scheduling problems for several products on identical parallel lines with limited capacity. For the case with two products produced in single period has been proposed new model with integer variables describing number of machines set up to process some produet.
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