68 2 Modelling Basics
Therefore, any software model can be viewed as a set of programs and data.
Software models can be kept or transported on a medium, but the medium alone is
not enough to allow the model to “come to life”. This can be achieved only when
the model is loaded in some hardware, and the control is transferred to it. Thus, we
can say that the model “lives” in its host – typically, a computer.
Without software no computer can directly be used to represent anything.
When we say that something is “modelled with computer” we mean: “modelled by
means of software running on a computer”. Thus, a
computer model is nothing else
than a software model that is loaded into a computer and activated there. In other
words, both terms can be viewed as synonyms referring to a system consisting of
hardware, programs and data. The main difference is that each of the terms stresses
a different aspect of this kind of modelling,
e.g. the use of software or the use of
hardware, with the respective specificities.
2.4.2.3.2.7 Computer Aided Systems
A Computer Aided system or in short CA-system (also spelled without dash) is a
complex software system, dedicated to solving tasks in a specific subject area. The
subject area is typically a phase of the product lifecycle (design, planning,
manufacturing, marketing,
etc.) or an activity existing in many phases (e.g., quality
control, product-data management) and its name is usually reflected in both the
long and the short forms (
e.g., Computer Aided Manufacturing system or CAM
system). The alternative short form
CAx-system is often used as a collective name
for all possible short forms, where “x” is a placeholder, matching the name of any
phase or activity. The “computer aided” is not really an obligatory part of the
name, since it is implied for numerous activities. Thus, nobody would speak about
word-processing without some kind of computer, but the respective “computer
aided” system – the word processor or word-processing system – meets the
definition and should be considered as belonging to the group of CAx-systems, too.
When several CAx-systems are used to automate related activities and are
developed from the same producer they are often referred to as
software packages,
software packets or suites.
2.4.2.3.2.7.1 CAx-model
The usage of CAx-systems has become so common during recent decades that
many people tend to forget: most CAx-systems create as one of their outputs a
model (CAD-model, DMU-model, FEM-model,
etc.). This model is often either
the most important or the only result produced.
Some of these CAx-models are product models, some of them are object
models (
i.e., something that is not going to be produced, but is used as part of other
models) and some are models of processes. Therefore, the term CAx-model is used
in the text as a generic term, referring to models of any of the types mentioned.
2.4.2.3.2.7.2 CAx-system Centred Approach
For each product several different product models, related to different phases or
aspects of its lifecycle, are created and used. Typically, the model related to a
given phase or aspect is prepared by a dedicated (CAx) system and can be
modified and further developed only by
identical (i.e. having the same
type/dedication
and from the same producer) or compatible (i.e. capable to read the
models in their initial format) system. Even more important is that the models,