1.Physical model
Also can be called entity model,and can be divided into physical model and simulation model.
1)Physical model:Made according to the similarity theory scaling according to the original(also
can be enlarge or the same size with original),such as aircraft model in wind tunnel experiments,
the experimental model of hydraulic system ,architecture model, ship model, etc.
2)Simulation model:In the different physical fields systems(mechanical,electrical,thermal,fluid
mechanics,etc) ,each variable sometimes obey the same rule,according to the common law can
make analogy and analogic model with completely different physical meaning.For example, the
pressure response of the pneumatic system in certain conditions composed of throttle and
air-capacitor with the output voltage of the circuit composed of resistance and capacitance have
similar law,so easy to make experiment circuit to simulate pneumatic system.
2.Mathematics model
The model described in mathematical language. The mathematical model can be one or a set
of algebraic equation, differential equation, differential equation ,integral equation, or statistical
equation, it can also be some appropriate combination, quantitatively or qualitatively by these
equations describe the relationship between the variables system or causal relationship. In
addition to the mathematical model described in equation, and with other mathematical tools,
such as algebra, geometry, topology, mathematical logic description model. Need to point out
that mathematical model describes the behavior and characteristics of the system rather than
the actual structure of the system.
3.Structure model
Mainly reflect system structure characteristics and causation relationship model. One of the
most important models in structural model is model figure. In addition atrioventricular model
is commonly used in analysis of biological systems also belongs to the structural model. The
structure model is an effective method for the study of complex systems
4.Simulation model
The model through digital computer, simulation computer or mixed program to run . Using the
appropriate simulation language or program, physical model, mathematical model and structure
model can generally turn into the simulation model. On the influence of different control strategies
or design variables of the system, or system affected by disturbance after some possible, better
to experiment on the system itself, but it is not always feasible. There are a variety of reasons,
such as: the experiment may be expensive; System may be unstable, the experiment may destroy
the balance of the system to be dangerous; System time constant is large, the experiment takes
a long time; the system to design did not exist.
