Decision support system for production control: Multiple criteria decision making in practice

This paper presents a development of decision support systems for solving scheduling problems. It consists of two parts — the first describing the production processes which can be handled by the system and the second describing how the system works.

Visszutas logisztika és termeléstervezés (Reverse logistics and production planning)

A dolgozat a visszutas logisztikát, az újrahasznosítást igyekszik beilleszteni a vállalati termeléstervezés keretei közé. A szükséglettervezési rendszerek (material requirements planning, MRP) célja a készletek és beszerzendő anyagok, alkatrészek időben ütemezett gyártásának és beszerzésének megtervezése. A klasszikus MRP rendszereket az utóbbi időben próbálja a tudomány az újrahasznosítással kibővíteni. Mivel ebben az esetben az új, és újrafelhasználható anyagokat külön kell nyilvántartani, ezért az MRP-táblák és készletek növekednek. A rendelési tételnagyságok meghatározása is nehezebb, összetettebb tételnagysághoz vezet. A dolgozatban egy visszutas logisztikai készletmodellt ismertetünk, valamint annak dinamikus kiterjesztését, amely alapja lehet az SAP-ba beépíthető rendelés állomány meghatározó heurisztikának. ____ The aim of the paper is to extend production planning with reverse logistics and reuse. Material requirements planning (MRP) systems plan and control invetory levels and purchasing activities of the firm. In the last decade scientists on this field try to involve reverse logistics activities in MRP systems. Size of MRP-tables is growing in this case because of the alternative use of newly purchased products and reusable old items. Determination of order quantities will be more complex with these two modes of material supplies. An EOQ-type reverse logistics model is presented in the paper with a dynamic lot size generalization. The generalized model can be seen as a basic model to build in production planning and control system like SAP.

Consistency of the decision-maker in pair-wise comparisons

Most authors assume that the natural behaviour of the decision-maker is being inconsistent. This paper investigates the main sources of inconsistency and analyses methods for reducing or eliminating inconsistency. Decision support systems can contain interactive modules for that purpose. In a system with consistency control, there are three stages. First, consistency should be checked: a consistency measure is needed. Secondly, approval or rejection has to be decided: a threshold value of inconsistency measure is needed. Finally, if inconsistency is ‘high’, corrections have to be made: an inconsistency reducing method is needed. This paper reviews the difficulties in all stages. An entirely different approach is to elaborate a decision support system in order to force the decision-maker to give consistent values in each step of answering pair-wise comparison questions. An interactive questioning procedure resulting in consistent (sub) matrices has been demonstrated.