5.7 Study of Intensity Fluctuation Spectra of Dynamic …
419
during repeated mounting of the illuminating–receiving sensor into the point under
study (another area of skin and therefore distance from its surface to the face of the
light guides) as well as changes of geometry of the experiment at different degrees of
contraction of the skeletal muscle, etc. The second large group of conditions includes
distinctions of reflectivity of different skin areas, impact of the physiological state
of a patient, etc.
As the given measurements of medical–biological objects in vivo are unstable
and have a great confidence interval, special attention should be paid to the maximal
possible repetition of identity of conditions of the experiment as well as the set
of the needed statistics. Also, this reason explains the usage of integral informative parameters mostly. The structure of the curves obtained in the same conditions is not preserved; meanwhile, their more conservative integral characteristics
are significantly more resistant.
Taking into account the stated uncertainties of measurements as the informative
ones, it is reasonable to choose not absolute, but relative indices of spectrograms,
which are normalized to the zero harmonic, maximal spectrogram amplitude or to the
area of the spectral curve, etc., and to base methods of diagnostics on the comparative
principle.
One of rather evident-registered experimental facts is the increase of amplitude
of spectral harmonics; moreover, this change is observed in the area of low as well
as higher frequencies.
The dependence of maximal value on the applied load is shown in particular in
the works [80–82]. The common growth of spectral amplitudes is accompanied by
the growth of the area under the spectral curve, respectively.
The calculation of the area was conducted for the primary spectra as well as
for the smoothed spectra. Simultaneously, the same study was conducted with
an electromyography (EMG). The calculation of the spectrum was conducted in
the frequency range of 0–62.5 Hz due to the realization of 1024 dots (sampling
time is 8 s).
The increase of the width of spectral harmonic (sectionalization) was applied to
enhance stability of the obtained results of measurements during spectrum calculation, and also the averaging of spectra of several consecutive signal selections was
conducted.
The use of the enumerated methods requires the length either of the selection or
of their number that finally leads to the increase of time of measurement. But as
the results showed time of measurement is limited by the capability of a testee to
hold the maximal loads. If load P was 10 kg, this time did not exceed 1.5–2 min for
such muscles as a biceps. Meanwhile, the number of realizations was chosen to be
10 in the range of 62.5 Hz. The previous chapters have shown that calculations and
model experiments for longitudinally oscillating diffuser gave the possibility to use
the area under the spectral curve (spectrum power) as an informative parameter of
the spectrum, which characterizes oscillating activity of human skeletal muscles:
419
during repeated mounting of the illuminating–receiving sensor into the point under
study (another area of skin and therefore distance from its surface to the face of the
light guides) as well as changes of geometry of the experiment at different degrees of
contraction of the skeletal muscle, etc. The second large group of conditions includes
distinctions of reflectivity of different skin areas, impact of the physiological state
of a patient, etc.
As the given measurements of medical–biological objects in vivo are unstable
and have a great confidence interval, special attention should be paid to the maximal
possible repetition of identity of conditions of the experiment as well as the set
of the needed statistics. Also, this reason explains the usage of integral informative parameters mostly. The structure of the curves obtained in the same conditions is not preserved; meanwhile, their more conservative integral characteristics
are significantly more resistant.
Taking into account the stated uncertainties of measurements as the informative
ones, it is reasonable to choose not absolute, but relative indices of spectrograms,
which are normalized to the zero harmonic, maximal spectrogram amplitude or to the
area of the spectral curve, etc., and to base methods of diagnostics on the comparative
principle.
One of rather evident-registered experimental facts is the increase of amplitude
of spectral harmonics; moreover, this change is observed in the area of low as well
as higher frequencies.
The dependence of maximal value on the applied load is shown in particular in
the works [80–82]. The common growth of spectral amplitudes is accompanied by
the growth of the area under the spectral curve, respectively.
The calculation of the area was conducted for the primary spectra as well as
for the smoothed spectra. Simultaneously, the same study was conducted with
an electromyography (EMG). The calculation of the spectrum was conducted in
the frequency range of 0–62.5 Hz due to the realization of 1024 dots (sampling
time is 8 s).
The increase of the width of spectral harmonic (sectionalization) was applied to
enhance stability of the obtained results of measurements during spectrum calculation, and also the averaging of spectra of several consecutive signal selections was
conducted.
The use of the enumerated methods requires the length either of the selection or
of their number that finally leads to the increase of time of measurement. But as
the results showed time of measurement is limited by the capability of a testee to
hold the maximal loads. If load P was 10 kg, this time did not exceed 1.5–2 min for
such muscles as a biceps. Meanwhile, the number of realizations was chosen to be
10 in the range of 62.5 Hz. The previous chapters have shown that calculations and
model experiments for longitudinally oscillating diffuser gave the possibility to use
the area under the spectral curve (spectrum power) as an informative parameter of
the spectrum, which characterizes oscillating activity of human skeletal muscles: