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Áåëîðóññêèé ãîñóäàðñòâåííûé ýêîíîìè÷åñêèé óíèâåðñèòåò
Petri nets in business processes modeling
Creation of systems
of efficient organisations management is one of the major problems facing to the
modern business. Active introduction of the information technology providing a
regulation of business processes in a control system is directed on increase of
activity efficiency of the organisation, basically at the expense of creation
of production costs decrease.
Business processes modeling
acts as an effective remedy of optimisation ways search in organisation
activity, as a mean of planning, forecasting and minimisation of the risks
arising at various stages of live ability of the enterprise. In these
conditions the great value is got by the information on efficiency of the
organisation of employees’ work of the enterprise participating in realisation
of certain business processes. Such information allows operating costs on
manufacture and selling of products (services).
Traditional methods
of an estimation and costs planning are focused on a final stage of creation of
a product and do not consider cost of the processes carried out thus which is
creating and not creating value for consumers. For the purpose of revealing,
analysis, estimation, and also optimisation of these processes (first of all those
that don’t create value for consumers), it is expedient to use modern
information technologies, allowing to model business processes of the various
organisations. Model construction allows specifying inconsistency of
operations, their duplication, optimum sequence of accomplishing, etc. The
means of business processes modeling give the chance to carry out their cost
analysis. With its help it is possible to reveal and reduce the price of
expensive operations, to determine and exclude excessive operations and, thus,
to reduce cost of manufactured production (services).
Nowadays a number
of the technologies intended for business processes modeling are known. However
the widest application in practice of the foreign and domestic enterprises was
received by CASE-technologies. To the technologies of the given kind concern
the means of a simulation modelling on the basis of Petri nets. With their help
it is possible to describe and analyse duration of accomplishing and
interaction of operations in processes for the purpose of revealing of
bottlenecks of system, and also to specify size and reserves of reducing of
expenses of human, financial and other resources on accomplishing of these
processes. The basic advantages of using Petri nets for business processes modeling
include the following: 1) the process specified in terms of Petri nets has
clear and accurate idea; 2) presentation of a drawing network construction
thanks to which all its determinings and algorithms are easily perceived; 3)
possibility of using set of methods for the analysis.
Petri net is
represented by the focused count with tops of two types – positions and
transitions. In the position of net markers (counters) are located. Their moving
displays dynamics of modeled processes. Traffic of markers results from
accomplishing of transition under the influence of outage events.
Process modeling
«Accomplishing of clients’ orders » on the basis of Petri nets has been
performed at the Belarus enterprise of Open Society "Minskcontract". The
basic direction of organisation activity is a wholesale trade of material
resources. The organisation sells a wide spectrum of production of industrial, cultural
and community appointment. The
industrial enterprises, the enterprises of agroindustrial and building
complexes, housing and communal services and other organizations are among its
buyers. However the greatest share in the aggregate turnover volume makes
social sphere (culture establishments, formations, public health services and
social security) – 55,8 %.
At process modeling
«Performance of clients’ orders » network transitions (t1, t2,
… t9) look like vertical lines and correspond the sets of operations
on process performance. Positions are represented by ovals and correspond to the
conditions of transitions. By arrows the arches connecting tops the column of
different type are shown. In a position of a network as markers (counters)
objects – orders from the various enterprises, arriving on "Minskcontract
" (Pn) and resources (R1), corresponding to stocks
of the goods at depot the organisations act.
As
an entrance place of a network (P1) act the orders which have
arrived in the organisation (in the form of demands) from buyers, and target
places – delivered (P10) or taken out by transport of the client (P11)
the completed orders.
The
analysis of behavior variants of Petri net was made on the basis of a tape of
the approachability having the linear representation form of the set of final
network conditions (Sn), achievable of its initial condition (S0).
So, to an initial condition of the network constructed for process «Performance
of clients’ orders» on "Minskcontract", there correspond two orders
which have arrived in position P1. As a result of the spent
calculations it has been revealed that the approachability tape has 15 final
condition statuses (both orders are rejected – S3; one order is
rejected, one – is provided and delivered to the client – S7, etc.).
Analyzing them, it is possible to draw a conclusion that the network is
constructed correctly. It means that in a network there are no not final
deadlock condition statuses in which any transition is not activated, and also
there are no cycles without an exit.
On the basis of the
spent analysis of a correctness of construction of Petri net the scheme of
process including 5 basic operations has been made: acceptance and handling of
orders (Î1), an estimation of a stock position of the goods at depot
(Î2), a complete set of orders (Î3), expectation of
delivery of the necessary goods (Î4), dispatch of orders (Î5).
Application of the
constructed model to accomplishing concrete orders of the enterprise "Minscontract",
has allowed to specify optimum time on each operation and process as a whole. On the basis of participating
in realisation of process resources time and cost, costs on performance of each
order have been calculated, which have appeared on the average on 15-20 % below
planned. Profitability of performance of orders has accordingly grown.
Literature
1. Petri, C.
Fundamentals of a Theory of Asynchronous Information Flow / C. Petri //
Proceedings of the 1962 IFIP Congress. – Amsterdam, North Holland, 1962.
2. Peterson, J. Petri
Net Theory and the Modeling of Systems / J. Peterson. – Prentice Hall, 1981.
3.
Ãàìàþí, È.Ï. Ðàçðàáîòêà
èìèòàöèîííûõ ìîäåëåé íà îñíîâå ñåòåé Ïåòðè / È.Ï. Ãàìàþí. – Õàðüêîâ: ÍÒÓ «ÕÏÈ», 2002. – 143 ñ.