3.1 Application of Mathematics in a
Garden Sprinkler
In this case the working group uses the LU
factorization to explain how a sprinkler works. LU
decomposition is a matrix decomposition which
writes a matrix as the product of a lower triangular
matrix and an upper triangular matrix. This
decomposition is used in numerical analysis to solve
systems of linear equations.
3.1.1 Movement of the Sprinkler
Depending on the position of the output link of four-
bar mechanism, the sprinkler will water one way, on
the other or both ways.
The elements of the sprinkler are:
Turbine and worm 1 and crown wheel 1: Water
affects some pressure on the blade by rotating
turbine. On the turbine shaft is located a screw
endlessly rotates the turbine. This screw
engages with a cogwheel. The mission of this
gear system is to reduce speed.
Worm 2 and crown wheel 2: Again, another
mechanism of worm and crown wheel reduces
speed to reach the four-bar mechanism.
Mechanism of four-bar linkage: The links are
connected by joints that allow the rotation of a
rigid body over another.
3.1.2 System of Linear Equations
The system of linear equations is obtained from
dynamic analysis of four-bar mechanism. For
resolution the Mathematica software is used, with
the implementation of some functions to get the LU
factorization, decomposing the matrix obtained with
real data, in two others. This is the way to calculate
the forces acting on the links.
3.2 Functions of Complex Variables
Before finalizing any design, should be checked how
it reacts with airflow to achieve a perfect
combination of aesthetics and performance. To
perform this check, used the so-called wind tunnel,
which is a compound which simulates actual air
flow. The components of this device are:
Cavity to stabilize the flow establishment.
The reduction cone compresses the air volume
increasing speed
Test section where the model stands.
Diffuser that reduces the wind speed.
Thinking about wind tunnel students quickly
relate it to the world of motoring, and particularly
with the automobile and aeronautics, but the reality
is that the wind tunnel has a very broad utility, from
skiers to missiles, through buildings or trains.
For general modelling the potential flow is
considered, excluding something as common as the
turbulence. The purpose of complex analysis is to
calculate the coefficient of wind resistance, and the
results of the flow lines. Due to the nature of certain
flows, longitudinal sections along the flow lines can
be considered for analysis. This remains then a two-
dimensional system that can be analyzed
mathematically using the complex plane where one
element is given by a complex expression.
Because of the complex analysis requires
millions of calculations, CFD (Computational Fluid
Dynamics) has been developed to analyze and solve
problems concerning fluid flows.
3.3 Partial Differential Equations
Any differential equation that contains partial
derivatives is called partial differential equation. In
any partial differential equation, the dependent
variable (unknown function) should be a function of
at least two independent variables since otherwise
would not appear partial derivatives.
The vibrations that occur during driving, flying,
travelling by train, or those produced by a machine
tool during cutting, which suffer the blades of a
turbine rotating at several thousand revolutions per
minute or vibration that supports a building during
an earthquake are usually governed by the wave
equation.
A membrane attached by the edge and under
uniform tension, the ideal patch of a tambourine,
vibrates according to a partial differential equation.
And also the heat equation, which describes how to
distribute the temperature versus time and space,
follows another type of partial differential equation.
3.4 QR-codes
In this issue we found the example of how the
amount of information available on the Internet is
not enough to find the solution to a problem. This
group of students wanted to find an application of
the QR decomposition, which writes a matrix as a
product of an orthogonal matrix and an upper
triangular matrix, and multiply the factors, and
iterate, but what they found were the QR codes, a
matrix code created by Denso-Wave corporation, to
ICEIS 2010 - 12th International Conference on Enterprise Information Systems
156