Logistics-based modeling
Instructor's Guide
intro,
objects
modeling,
simulation,
visualization,
legacy
summary,
Q/A,
literature
Improvements in business performance
and productivity may be achieved by critically
examining some of the rules
that govern a business process.
Business process redesign (BPR) is the
generic label for many emerging methodologies aimed at producing these
improvements. Re-design
implies that the current state of affairs is no longer acceptable and
can no longer be refined or evolved.
Despite the importance of qualitative assessments
in BPR, as noted in [Hammer90], for modeling
we favor a more quantitative approach
for which we provide support by means of
a simulation library (BPSIM) based
on the logistics-based business modeling method (LBM)
presented in [Gerrits95].
Logistics-based modeling -- criteria for redesign
- the time spent in executing a business process.
Product lead time -- time between order and delivery
- processing time -- actual working time
- queue time -- waiting for a resource
- setup time -- for the job to get started
- wait time -- waiting for a job to complete
- transport time -- between resources or operations
slide: Logistics-based business models
Logistics-based modeling
allows for analysing
the time spent in executing a business process.
The product lead time is defined as the time
that passes between the moment a customer orders
a product and the moment a product is delivered.
In more detail, we can distinguish between
processing time
(the time actually worked on a job or operation),
queue time
(the time a jobs waits for a resource to become available),
setup time
(the time that passes between the moment
a resource becomes available and the moment
work on the job is started),
wait time
(the time that is spent waiting for another job
to complete), and
transport time
(the time that is needed to move a job from
a resource at a certain location to a resource
at another location).
For a particular model,
measurements may be obtained by
running a series of simulations.
Based on an analysis of the simulation results,
alternative models may be proposed.
For example, when the setup time for a job is
relatively large, combining jobs into a single task
for an employee may be more efficient.
The LBM method offers a number of primitives,
with associated graphic icons,
from which a business process model may be constructed
as a network of resources
connected by transport arcs.
Logistics-based modeling primitives
- operation --
processing component
- task -- a series of consecutive operations
- transport -- transport of information
- choice -- affects flow of information
- organizational units --
to represent departmental boundaries
- external agents --
opaque
entities
- archives --
paper-based storage facilities
slide: Logistics-based modeling primitives
The primitive entities offered by LBM are listed in slide [lbm-prim].
Operations are atomic in the sense that wait time,
queue time and transport time may not be part
of an operation.
Only setup time and process time are part of an operation.
Tasks are introduced to allow for a series of jobs
or operations
to be processed, for example by one employee,
in order to reduce the setup time needed.
Transport entities represent the time it takes
for information to flow from one resource
(that is operation or task) to another.
Transport implicitly defines the
sequential structure of a process.
However, duplications of information, and consequently
parallel operations, are allowed.
In addition to the primitives mentioned above,
LBM allows us to characterize
organizational units
to represent departmental boundaries,
external agents
to represent opaque information producing or
consuming entities,
and
archives
to represent paper-based storage facilities.
Also, employees may need additional
means
to engage in an operation or task.