Page 178 - DCAP601_SIMULATION_AND_MODELING

Simulation and Modelling

Notes

Notes The slack time is the amount of time the task can be slipped by without moving the
end date of the process. The critical path can now be identified as all paths through the
network where the slack time is zero.

Figure 10.4: Calculating the Slack and finding the Critical Path

10.2 Simulation of an Activity Network

An object-orientated simulation approach towards an integrated planning of production systems.
The main obstacle for an integrated use of simulation over different planning areas and stages
are the dissimilar views on a production system. Therefore, an object model is developed, which
enables the co-existence of different views and levels of detail in the same simulation model
while maintaining its consistency. This is attained by combining object-orientated technology
with a network based simulation approach. The prevailing idea is to offer the opportunity to re-
use existing models for the investigation of different aspects of a production system. The approach
is theoretically described as a conceptual object model and is thus, independent from a concrete
simulation language, tool or environment. The last part of this paper introduces the simulation
tool OSim, that implements this object model and demonstrates its usage through an example
Simulation is an application with high degree of intrinsic parallelism. This parallelism can be
beneficially exploited in a multiprocessor or multicomputer system to drastically reduce the
simulation time. Distributed simulation on slackly coupled systems involves problem
partitioning into components, allocation of components to computing systems, communication
and co-ordination between components. This paper addresses itself to these problems for
distributed simulation of activity networks used for planning and scheduling of physical projects.
We discuss conditions under which project network can be decomposed into sub-project networks
so that the sub-projects can be simulated independently. The integration is achieved through the

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