Chapter 4 DEVS Formalism

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Chapter 4DEVS Formalism

• Basic DEVS Formalism
• Examples
• Coupled DEVS Specification
• Closure Under Coupling
• Hierarchical Models

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Basic DEVS
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Basic DEVS Example Scuba Model
dint (five) for phase ! five ,surface1,
surface2 dint (five,s ) otherwise //except
when already on five
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Basic DEVS Example FireOnce Neuron and
Modifications
Use Continue(e) to retain next event time of
original pulse
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Basic DEVS Example FireOnce Neuron and
Modifications (Continued)
input
t
fire
phase
state
refract
sigma
elapsed time
pulse size 3
output
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Coupled Model Specification
DN lt X , Y, D, Mi , Ii , Zi,j gt
X a set of input events. Y a set of output
events. D an index set (names) for the
components of the coupled model. For each i Î D
, Mi is a component DEVS model. For each i
Î D È self , Ii is the set of influencees of
i . For each j Î D È self ,
Zi,j Yi ? Xj is the output translation
mapping
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Closure Under Coupling