grasped. To describe the process of scenario
evolution, firstly, it is necessary to clarify the current
state of the disaster event and the information of the
accident scene, and then infer the evolution route and
possible consequences of the event by objective and
scientific means.
2.1 Elements of Scenario Deduction
Model
To reflect the real situation of disaster evolution,
emergency decision makers should first extract the
key scenarios of a disaster that can describe the
disaster situation in a certain time period. In the
deduction of fire scenarios in commercial complex
buildings, the key scenarios are the real fire situations
faced by fire fighting and rescue decision makers. In
the scenario evolution process, in addition to
identifying the key scenarios in an accident, the
emergency environment in which the scenarios are
located and the measures taken by emergency
decision makers for each scenario are also identified.
Therefore, the commercial complex fire scenario
evolution process contains four main elements:
situational state, emergency measures, emergency
environment, and evolution of the situation. The
evolutionary network is established using a symbolic
language to characterize the relationship between the
elements, as shown in Figure 1.
Figure 1: Basic units of scenario evolution.
S denotes the current situational state; P denotes
the emergency measures to be taken in this situational
state S; and E denotes the current environmental
situation of the fire, i.e., the emergency environment.
Under the influence of fire emergency measures and
the emergency environment, scenario S will change
and then jump to scenario S
1
, which is a scenario unit
of scenario evolution.
2.2 The Law of Scenario Deduction
The complexity of the fire disaster evolution process
is determined by the specificity of the regional
system of commercial complexes. In addition to the
evolution of the fire accident scenario itself, the
correlation between the systems, the complexity of
the emergency environment, the effectiveness of
emergency measures and other factors often cause the
chain evolution of other secondary hazards,
eventually forming an evolutionary network of
multiple paths. As shown in Figure 2, the scenario S
1
appears in the commercial complex building at the
moment t
1
, and S
1
evolves to S
2
under the joint action
of the emergency environment E
1
and emergency
measures P
1
. As time advances, the dynamic
evolution of the scenario goes from the initial
scenario S
1
through a series of evolutionary scenarios
S
2
, S
3
β¦ S
n-1
and finally reaches the termination
scenario Sn.
Figure 2: Scenario deduction rule.
3 FUNDAMENTALS OF
BAYESIAN NETWORK
A Bayesian network is a directed acyclic graph
representing probabilistic dependencies among
variables, consisting of nodes representing variables
and directed edges connecting these nodes. Bayesian,
as a probability-based uncertainty inference method,
is an important tool for dealing with uncertain
information. Due to the complex building
environment of commercial complexes and the
changeable path of fire evolution process, it is more
practical to use Bayesian network to simulate the fire
evolution process.
3.1 Construction of Bayesian Network
When a fire broke out in a commercial complex, the
current scenario of the incident was identified.
However, the real scenario of the fire keeps changing
over time. This paper extracts key scenarios and
influencing factors by combining the experience of
experts in the field and the law of fire evolution in
commercial complexes, and then the evolution
network is established by symbolic language. In this
paper, nodes are used to represent the key elements in
the evolution process, and directed edges are used to