Modelling Approaches for Bio-Manufacturing Operations - Measurement, Monitoring, Modelling, and Control of Bioprocesses - page 91

2.2 User Interfaces
When developing a model, one important feature is to provide a user-friendly front
end for data entry or retrieval of the simulated outcomes. A simulation may be
used by those involved directly in bench-scale process development activities or
those in more supervisory or managerial positions. Hence where applicable and to
cater for this potentially wide range of users, it is important that the software is as
intuitive as possible. Appropriate user interfaces are needed to make it easy for
people to enter data, and a simple, clean interface with clear labels for exactly
which data values are needed is essential, ideally with the capability to validate the
inputs so as to avoid basic mistakes.
2.3 Modelling Inputs
Depending upon the type of model, various classes of input parameters (or choices
for modelling) may be needed. Some of these may be categorised as follows under
the appropriate property heading, although depending upon the nature of the model
there may be additional factors to consider such as those relating to other parts of
the supply chain or production that sit 'outside' the scope of the principal man-
ufacturing process steps:
• Feed E.g. selection of volumes or titres
These properties have a direct impact upon processing schedules,
since larger quantities of product will require either a larger
downstream process capacity or may necessitate the process to be
cycled more often to cope with the higher overall throughput. The
use of higher feed titres may also have other effects that may need
to be modelled e.g. to adjust column loading times to prevent
excessive breakthrough and product loss.
• Equipment E.g. the number, type and sequence of unit operations
The quantity and sizing of unit operations are critical in ensuring
that the production, recovery and purification duty can be satisfied
e.g. making sure that a centrifuge bowl or a filter membrane provides
an adequate separation area to carry out its task. Models can be used
to determine whether the individual unit operations in a process are
the most suitable e.g. whether a pre-clarification membrane step
before a column is indeed adequate or whether additional steps are
needed to remove foulants and thus maximise column lifetime.
• Operational E.g. flow rates, agitator driveshaft speeds and bowl RCF values
These key parameters have a direct influence upon the performance
of a process step. Appropriate values should be chosen so as to
satisfy the objectives of the entire process sequence. Such terms