MYSTERIES OF THE EQUILATERAL TRIANGLE - HIKARI Ltd

86 Applications
Figure 3.11: Warren Truss [63]
combines strength with economy of materials and can therefore be relatively
light. It is an improvement of the Neville truss which employs a spacing
configuration of isosceles triangles. The first bridge designed in this way was
constructed at London Bridge Station in 1850.
Application 12 (Flammability Diagram). Flammability diagrams [334]
show the regimes of flammability in mixtures of fuel, oxygen and an inert gas
(typically nitrogen).
The flammability diagram for methane appears in Figure 3.12. Prominent
features are the air-line together with its intersections with the flammability
region which determine the upper (UEL=upper explosive limit) and lower
(LEL=lower explosive limit) flammability limits of methane in air. The nose of
the flammability envelope determines the limiting oxygen concentration (LOC)
below which combustion cannot occur.
Application 13 (Goethe’s Color Triangle). In the Goethe Color Triangle
[145], the vertices of an equilateral triangle are labeled with the three primary
pigments, blue (A), yellow (B) and red (C).
The triangle is then further subdivided as in Figure 3.13 with the subdivisions
grouped into primary (I), secondary (II) and tertiary (III) triangles/colors.
The secondary triangle colors represent the mix of the two adjacent
primary triangle colors and the tertiary triangle colors represent the mix
of the adjacent primary color triangle and the non-adjacent secondary triangle
color. Goethe’s color psychology asserted that this triangle was a diagram of
the human mind and he associated each of its colors with a human emotion.
Subregions of the triangle are thus representative of a corresponding emotional
state.