A Case studies of the GRAMS reference model - Modeling and Simulation of Complex Systems - page 182

Name Unit Description

C all Euro Overall costs (warehouse, workers, forklifts),

without taking inventory into account.

C inv Euro Average value of inventory (Precision: minutes)

U min

% Minimum utilization of warehouse.

U avg

% Average utilization of warehouse.

U max

% Maximum utilization of warehouse.

U min % Minimum utilization of workers.

U avg % Average utilization of workers.

U max

% Maximum utilization of workers.

U min

% Minimum utilization of forklifts.

U avg

% Average utilization of forklifts.

U max % Maximum utilization of forklifts.

Irrelevant objects and aspects of real system

Incoming and outgoing trucks are not part of the model. Instead,
the platforms for incoming and outgoing articles form the model
boundary.

The size of articles is neglected, i.e., all articles have the same size.

Decomposition into submodels As illustrated in Figure A.1 the
model is decomposed into the submodels SM 1, SM 2, and SM 3
which represent the components of the GRAMS reference model.

Macro-level: Simulation time

For the simulation time , a discrete time domain is chosen, i.e., T =
N . It is assumed that the simulation starts at an

arbitrary point in time t start = 0 and ends at t end . In order to allow a
precise description of the movement of workers and forklifts a single
time step represents 0.1 seconds. Table A.2 illustrates the relation of
simulation time to real time.

= { 0 , 1 , 2 ,... }