Civil Engineering Reference
In-Depth Information
Fig. 13.3
Normal
distribution
f
(
x
)
x
m
x
Fig. 13.4
Log normal
distribution
f
(
x
)
X
m
13.8.4
Log Normal Distribution
This distribution is provided when two or more normally distributed parameters
being combined to provide a single distribution. The log-normal distribution is the
combination of two or more variables which are normally distributed.
Log-normal distribution (Fig.
13.4
) is defi ned by two parameters of mean and stan-
dard deviation in log space. Other used names for log-normal distribution are Cobb-
Douglas and anti-log-normal distribution. There are also other types of log-normal
distributions that are characterized by more than two parameters (McLaughlin
1999
).
13.8.5
Triangular Distribution
This distribution usually is useful when the choices are minimum, maximum and
most likely value of some occurrence. The triangular distribution (Fig.
13.5
) is a
continuous distribution that is often used in fuzzy logic applications.
In a building simulation context it is a useful distribution because it is described
by minimum, maximum and most likely values. For example, the typical use light
in a space can be augmented by a minimum and maximum to characterize the pos-
sible range.
