Studies on the Experimental Validation of the Theoretical …
179
(L w , a, b) =
N
k
L eq (x 1k , x 2k , x 3k , L w , a, b) − L eq exp k
2
(4)
with the next restrictions:
100.0 ≤ L w ≤ 140.0, 10.0 ≤ a ≤ 30.0, 0 ≤ b ≤ 17.0.
(5)
Because we have not studied in detail in qualitatively terms the functional (4),
we have limited to obtain relative minima (including the ends of the interval) only
aiming to achieve a value as close as the measured value at the smallest distance
from the engine.
2.3 Results
The distribution of the noise level around the tractor is the main result of this article.
The function minimization calculation (4), guided to the best approximation of the
maximum and minimum measured values, leads to the following values of the function parameters (3): L w = 90 dB, a = 18.307 dB, b = 12.786 dB. There are only
two values in the twenties that deviate over 10% from the mean value of experimental
data. The remaining 18 differences between experimental and theoretical data are
below 5.5% of the mean value of experimental data. Under these conditions, the
interpolation approximation (3), with the values of the parameters given above, is
considered satisfactory.
Using the interpolated noise level (3), to better understand its behaviour, is given
the graphical representations of Figs. 6, 7, and 8. The noise level function (3) is a
function of three real variables. The representation of the function as the surface of
Figs. 6 and 7 is made for constant values of the vertical coordinate, x 3 . The noise
level distribution in Fig. 6 corresponds to the most likely vertical coordinate of the
human operator’s ear which works on the sowing plant or on the miscanthus planting
machine. The vertical coordinate corresponding to the noise distribution in Fig. 7
is most likely for the ears of agricultural workers from the cucumber or strawberry
harvest machine.
The variation of the noise level in the direction of the trajectory, for various
heights and values of the coordinate in the normal direction to the trajectory, is given
in Fig. 8. The horizontal area of the continuous curve x 2 = 0.227 m, x 3 = 0.000 m
in Fig. 8 corresponds to the length of the parallelepiped that borders the engine.
Noise level attenuation is observed, and is in accordance with scientific experience,
and measurement.
The values of the noise level at the ears of operators of trailed agricultural machines
are given in Table 2. The experimental and theoretical values can be used as arguments and considerations regarding the labour protection in the field of agricultural
machinery exploitation.
179
(L w , a, b) =
N
k
L eq (x 1k , x 2k , x 3k , L w , a, b) − L eq exp k
2
(4)
with the next restrictions:
100.0 ≤ L w ≤ 140.0, 10.0 ≤ a ≤ 30.0, 0 ≤ b ≤ 17.0.
(5)
Because we have not studied in detail in qualitatively terms the functional (4),
we have limited to obtain relative minima (including the ends of the interval) only
aiming to achieve a value as close as the measured value at the smallest distance
from the engine.
2.3 Results
The distribution of the noise level around the tractor is the main result of this article.
The function minimization calculation (4), guided to the best approximation of the
maximum and minimum measured values, leads to the following values of the function parameters (3): L w = 90 dB, a = 18.307 dB, b = 12.786 dB. There are only
two values in the twenties that deviate over 10% from the mean value of experimental
data. The remaining 18 differences between experimental and theoretical data are
below 5.5% of the mean value of experimental data. Under these conditions, the
interpolation approximation (3), with the values of the parameters given above, is
considered satisfactory.
Using the interpolated noise level (3), to better understand its behaviour, is given
the graphical representations of Figs. 6, 7, and 8. The noise level function (3) is a
function of three real variables. The representation of the function as the surface of
Figs. 6 and 7 is made for constant values of the vertical coordinate, x 3 . The noise
level distribution in Fig. 6 corresponds to the most likely vertical coordinate of the
human operator’s ear which works on the sowing plant or on the miscanthus planting
machine. The vertical coordinate corresponding to the noise distribution in Fig. 7
is most likely for the ears of agricultural workers from the cucumber or strawberry
harvest machine.
The variation of the noise level in the direction of the trajectory, for various
heights and values of the coordinate in the normal direction to the trajectory, is given
in Fig. 8. The horizontal area of the continuous curve x 2 = 0.227 m, x 3 = 0.000 m
in Fig. 8 corresponds to the length of the parallelepiped that borders the engine.
Noise level attenuation is observed, and is in accordance with scientific experience,
and measurement.
The values of the noise level at the ears of operators of trailed agricultural machines
are given in Table 2. The experimental and theoretical values can be used as arguments and considerations regarding the labour protection in the field of agricultural
machinery exploitation.