2.1 Modeling and Simulation
21
that, when implemented in a computer software, uses more than one simulation
paradigm” [Mu+2017, p. 1634]. Consequently, and in contrast to the definition
of some other scientists, the combination of DES and ABS is already seen as
a hybrid, even though both simulation approaches are based on a discrete time
progress. Brailsford’s approach is one of the few that emphasizes, that the
hybridization of simulation paradigms occurs in one model rather than by combining different simulators. While Tolk differentiates between “hybrid M&S
studies, in which various modeling paradigms are applied in an orchestrated
set of simulation tools, and hybrid M&S systems, where several such paradigms are used within one simulation” [Mu+2017, p. 1640], other scientists, e.g.,
Djanatliev, argue that in a hybrid model, the simulation paradigms need to have
a different resolution according to their time advance to be called ‘hybrid’ at all
[Mu+2017, p. 1636]. Following this logic, the term ‘hybrid simulation’ would
indicate the combined use of continuous and discrete simulation approaches,
while the combination of different simulation paradigms without a distinction between continuous and discrete should be referred to as multi-paradigm simulation
[Mu+2017, p. 1636]. Chahal even defines a spectrum for modeling, analysis,
and synthesis of hybrid systems, having hybrid approaches which constitute the
extension of continuous systems to model discrete events on the one end and
“on the other end […] discrete models extended to represent the behavior of
continuous models” [Ch2009, pp. 28–29]. In between those two extrema, mixed
discrete and continuous approaches, combining complementary aspects of both
techniques, can be found [Ch2009, p. 29].
The following definitions are applied in this work:
• Hybrid Simulation
Hybrid simulation represents the generic term for the use of at least two different simulation paradigms in one simulation model. The simulation paradigms
may have the same time progress.
• Combined Simulation
Combined simulation represents a sub-form of hybrid simulation in which
the simulation paradigms used follow a different time progress. Thus, the
combination of DES and SD or ABS and SD is called combined.
• Hybrid System Modeling
Hybrid systems modeling describes the combination of simulation techniques with methods from Applied Computing, Computer Science, Systems
Engineering, Artificial Intelligence, and OR.
21
that, when implemented in a computer software, uses more than one simulation
paradigm” [Mu+2017, p. 1634]. Consequently, and in contrast to the definition
of some other scientists, the combination of DES and ABS is already seen as
a hybrid, even though both simulation approaches are based on a discrete time
progress. Brailsford’s approach is one of the few that emphasizes, that the
hybridization of simulation paradigms occurs in one model rather than by combining different simulators. While Tolk differentiates between “hybrid M&S
studies, in which various modeling paradigms are applied in an orchestrated
set of simulation tools, and hybrid M&S systems, where several such paradigms are used within one simulation” [Mu+2017, p. 1640], other scientists, e.g.,
Djanatliev, argue that in a hybrid model, the simulation paradigms need to have
a different resolution according to their time advance to be called ‘hybrid’ at all
[Mu+2017, p. 1636]. Following this logic, the term ‘hybrid simulation’ would
indicate the combined use of continuous and discrete simulation approaches,
while the combination of different simulation paradigms without a distinction between continuous and discrete should be referred to as multi-paradigm simulation
[Mu+2017, p. 1636]. Chahal even defines a spectrum for modeling, analysis,
and synthesis of hybrid systems, having hybrid approaches which constitute the
extension of continuous systems to model discrete events on the one end and
“on the other end […] discrete models extended to represent the behavior of
continuous models” [Ch2009, pp. 28–29]. In between those two extrema, mixed
discrete and continuous approaches, combining complementary aspects of both
techniques, can be found [Ch2009, p. 29].
The following definitions are applied in this work:
• Hybrid Simulation
Hybrid simulation represents the generic term for the use of at least two different simulation paradigms in one simulation model. The simulation paradigms
may have the same time progress.
• Combined Simulation
Combined simulation represents a sub-form of hybrid simulation in which
the simulation paradigms used follow a different time progress. Thus, the
combination of DES and SD or ABS and SD is called combined.
• Hybrid System Modeling
Hybrid systems modeling describes the combination of simulation techniques with methods from Applied Computing, Computer Science, Systems
Engineering, Artificial Intelligence, and OR.