new competencies and
innovations in logistics

There are many reasons to use simulation:

• Models are too complex to analyse analytically.
• Handling stochastic phenomena.
• Creating "semi real life" environment for the learner.
• The need for "What if..." analysis.

Recent developments in PC hardware and software allow to develop simulation models not only for professional programmers but for users as well. Electronic spreadsheets do not need high qualifications in IT to build and run models. Dedicated simulation software supports the animation of operation and visualisation of results. The idea at the University of Veszprém was to combine the advantages of spreadsheets (simplicity, easy to use, visualisation (limited)) and the simulation approach. This synergy allows effective use in education because:

• No time requirement to learn the tool.
• Student and teacher-made models can be used as well.
• Models can be run in any average office environment.

Different software packages are used at University of Veszprém for these purposes:

• MS Excel (Electronic spreadsheet)
• VisSim (Visual Simulation)
• Powersim (Visual Simulation)
• Promodel (Production simulation with visulation)

Inventory and queue basically have the same model: "two-pole" with different input and output characteristics. A flexible model is able to represent both. (Figure C1 - C3).

Figure C1. Using different input and output policies inventories and queues can be analysed

Using the model shown in Figure C1 the student can try out the behaviour of an inventory control system in different circumstances. The characteristics of output - coming form the nature of the need - may differ. The characteristics of input - coming form the nature of the control and supply - may differ too. The learner can observe the results of any combination of input and output. The actual model in the Figure C1 has deterministic input and output. In this case EOQ can be used. EOQ (Economic Order Quantity) is a classic inventory optimalisation model. It trades off between the inventory holding and other (supply) costs. Model collects costs data related to simulation events (Figure C2).

Figure C2. Costs can be taken into consideration

Figure C3. Stochastic output, (s,q) order policy

Figure C3 shows a more difficult case: Stochastic output (coming from random demand). The freedom of selecting input and output characteristics allows to simulate not only inventories but queues with the same model.

The same model (purpose, characteristics) can be built using other software. Visualisation of the results is important in this case too (Figure C4). It shows that EOQ and other fixed period with fixed order quantity cannot be used in the case of random demand.

Figure C4. Inventory visual simulation using VisSim software

Figure C5. Queue visual simulation using VisSim software

The simulation is used in various education programmes:

• graduate programmes (engineering management, business administration);
• post-graduate courses;
• vocational education for professions (logistics assistant, logistics manager, production controller).

The Regional Labour Development Centre at Szombathely has also introduced the usage of these models, together with text books and videos. Unemployed people can register after an approval process. Then their fee would be covered by the office. It happened also that the office has bought a whole course.

• Better understanding of operations.
• Forecasting. At least to judge the projected behaviour of an inventory or queue system.
• In developing this kind of models, teachers also gain new competences.

These competences are useful for positions such as logistics assistants and logistics managers. Simulation "semi-practice" exercises give them a kind of "bridge" between principles, theory and practice.

1. It is time and labour consuming to prepare the models. This is only a problem in the early phase of application. After a certain period - as a result of the work of students and teachers - a "model library" can be created.
2. Limited functionality of spreadsheet and visual software. Difficult algorithms require additional programming. The optimal solution can be the combined use of software.
3. Under motivated students do not want to play with models. This problem seems to be the hardest. We have to prove the usefulness of this technique to the students.

The benefits of this kind of teaching/learning are the following:

• A better understanding of operation of logistics systems.
• Students can further develop the model.
• Complex, stochastic cases can be analysed.
• Participants are encouraged to build their own models, which makes the simulation - as an effective tool - more popular.

• The models are easily accessible for the students. For example via web (Link: http://www.vein.hu/~kovacsz "Download softwares" link.).
• Good understanding of real systems operation, policies.
• Easy to use user interface, references for further/deeper studies.
• Visualisation of results.
• This type of simulations could be used in other countries as well, because the same basic software is available there.