Let. 39, Št. 10 (2006)

Davorin Kofjač

UM FOV

Miroljub Kljajić

UM FOV

Povzetek

Background/Purpose: The objective of inventory management is to balance conflicting goals like keeping stock levels down to have cash available for other purposes and having high stock levels for the continuity of the production. Simulation approach is used to minimize total warehousing cost while no stock-outs occur and warehouse capacity is not exceeded. A case study of replenishment process optimization is presented on several representative materials of an automotive company using two replenishment algorithms: fix review period and full capacity ordering. The presented simulation results indicate considerable cost reduction without violating the mentioned constraints. The fuzzy logic evaluator, a decision support system used for simulation results assessment, is presented and discussed.

Hossein Arsham

University of Baltimore

Miroljub Kljajić

UM FOV

Povzetek

Background/Purpose: The use of simulation as a tool to design complex stochastic systems is often inhibited by cost. Extensive computer processing is needed to find a design parameter value given a desired target for the performance measure of a given system. The designer simulates the process numerically and obtains an approximation for that same output. The goal is to match the numerical and experimental results as closely as possible by varying the values of input parameters in the numerical simulation. The most obvious difficulty in solving the design problem is that one cannot simply calculate a straightforward solution and be done. Since the output has to be matched by varying the input, an iterative method of solution is implied. This paper proposes a “stochastic approximation” algorithm to estimate the necessary controllable input parameters within a desired accuracy given a target value for the performance function. The proposed solution algorithm is based on Newton’s methods using a single-run simulation approach to estimate the needed derivative. The proposed approach may be viewed as an optimization scheme, where a loss function must be minimized. The solution algorithm properties and the validity of the estimates are examined by applying it to some reliability and queueing systems with known analytical solutions.

Marko Žibert

ZZZS

Miroljub Kljajić

UM FOV

Povzetek

Background/Purpose: This article treats parallel service system modelling in the GPSS simulation language. The transactions entering such systems select between numerous different servers and we can mostly detect two rules in the selecting of the appropriate server. The first rule always gives the first few (regarding its position in the system) entities (either servers or queues) precedence over the others, while the second rule always treats all the equal entities evenly and selects among them quite randomly. Since GPSS normally operates by the first rule, we frequently come up against difficulties when modelling systems that serve by another rule. The present article offers a methodology how to solve this problem within GPSS.

Uroš Rajkovič

UM FOV

Olga Šušteršič

UL VŠZ

Jože Zupančič

UM FOV

Povzetek

Background/Purpose: This article presents the development of electronic documentation for community nursing using a system approach. Documentation is viewed as an information model for organizing and managing processes. The community nurse plans the nursing process after gather­ing and evaluating information on the patient’s health and his/her family status. Documentation is thus considered to be a basis for the successful work of the health team and as a way of ensuring quality in nursing. The article describes a prototype software model for e-documentation in community nursing together with its evaluation in practice

Andrej Škraba

UM FOV

Davorin Kofjač

UM FOV

Črtomir Rozman

crt.rozman@uni-mb.si

Povzetek

Background/Purpose: This paper presents an analysis of the periodicity solutions to the discrete anticipative cobweb model. Dubois’ anticipative principle was applied in the modification of Kaldor’s cobweb model. Characteristic solutions are gained through the application of a simulation, which determines the cyclical behaviour of supply and demand. Z-transform was applied in the determination of the solutions. The interconnec­tion between the anticipative definition of the cobweb model and Hicks model is addressed

Robert Rauch

Aerodrom Ljubljana d.d.

Miroljub Kljajić

UM FOV

Povzetek

Background/Purpose: This paper describes analysis of departure passenger flow in an airport terminal, from the passenger entrance to boarding; involving the development of simulation model. The basis for the simulation model was a snapshot of the passenger flow data taken during the summer periods from 2003 to 2004. Various data were collected and used to define the inputs to a simulation model. The next step was a statisti­cal analysis of the collected data. A discrete-event simulation model using simulation programming language General Purpose Simulation System (GPSS) was constructed. The performance of the system in the present and expected future was studied. The simulation model helped us to evaluate the passenger flow, identify the system bottlenecks as well as the system capacities. Critical aspects in the passanger flow through the airport terminal have been explored and studied. Recommendations based on the results of models runs were made.

Miroljub Kljajić