Page 278 - DCAP601_SIMULATION_AND_MODELING

Simulation and Modelling

Notes Model Building

Construction of SIMUL8 models is classically not based on programming or statistical data, but
rather on drawing organization schemes on the screen. However, SIMUL8 implements a two-
way interface with Visual Basic, which leaves space for creation of advanced model features,
which cannot be modeled using only the graphical interface. SIMUL8 also provides its own
simulation language based on Visual Basic called Visual Logic, which allows the user to implement
detailed logic of the simulation. The design of SIMUL8 also facilitates communication with
other software packages such as Microsoft Access, Excel and Visio. The support of XML and OLE
automation allows working with external sources of data and exporting internal data to other
systems. SIMUL8 also supports communication with databases using SQL.
Basic Components of SIMUL8 Environment

A SIMUL8 simulation gyrates around processing work items. They enter the system via work
entry points, pass through work centers, may temporarily reside in storage areas and leave via
work exit points. In addition to this mechanism, work centers may need specific resources to
process work items. A simulation consists of a number of these objects and of the routes between
them, modeled as a directed graph.
Component Description
Work item models physical or logical objects moving through the system. Entities enter the
(element, entity) system, induce different sorts of activities, use different kinds of resources and at
the end leave the system. A customer, product or document can be a SIMUL8
model entity.
Work entry objects that represent the entry of entities into the system (for example an arrival of
point (entrance) customer or formation of a product
Work center objects that model activities which the entities go through. Resources are typically
(activity, action) used during execution of an activity
Storage bin objects that model cumulation of entities. The stack usually precedes activities for
(queue, stack) which the stacked entities wait because of lack of resources
Work exit point a place through which the entities leave the modelled system (completion of an
(exit) order, leaving of a customer)
Resource objects that are used for modelling capacity restraints of workers, material or
(source) means of production used in activities
Route objects that connect all the other simulation objects. They represent sequences of
activities and thus the movement of entities in the system.

Typical Inputs and Outputs

These are the most regular parameters of a SIMUL8 model, which are set by the user to influence
the conditions of simulated environment:
1. Cycle times
2. Production rate

3. Capacity of production equipment
4. Arrival/order rates
5. Production rates of production equipment
6. Statistics of production equipment failures

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