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1.
We present the results of studying the multifractal structure of intermittency in a developed ionospheric turbulence during
special experiments on radio-raying of the midlatitude ionosphere by signals from orbital satellites in 2005–2006. It is shown,
in particular, that the determination of multidimensional structural functions of the energy fluctuations of received signals
permits one to obtain the necessary information on multifractal spectra of the studied process of radio-wave scattering in
the ionosphere. Experimental data on multifractal spectra of slow fluctuations in the received-signal energy under conditions
of a developed small-scale turbulence are compared with the existing concept of the radio-wave scattering within the framework
of the statistical theory of radio-wave propagation in the ionosphere. It is inferred that under conditions of a developed
ionospheric turbulence, the multifractal structure of the intermittency of slow fluctuations in the received-signal energy
is a consequence of the intermittency of small-scale fluctuations in the electron number density of the ionospheric plasma
on relatively large spatial scales of about several ten kilometers.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 6, pp. 485–493, June 2008. 相似文献
2.
We present the results of the first studies of the fractal structure of the developed small-scale ionospheric turbulence (SSIT)
during special experiments on radio-raying of the midlatitude ionosphere by signals from orbital satellites in 2005–2006.
It is established that under conditions of developed turbulence, typical values of the fractal dimension of the space occupied
by natural SSIT inhomogeneities are, as a rule, close to the topological dimension of their embedding space, and the true
values of the spectral index of isotropic SSIT only slightly differ from the corresponding generally accepted nominal values
in the embedding space. Nevertheless, even small differences in the mentioned parameters detected in the experiment witness
a sharply nonuniform distribution of the local fractal structures of the developed SSIT in space. We propose a stochastic
model of the nonstationary process for fast amplitude fluctuations of signals during their propagation in the ionosphere with
nonuniform spatial distribution of small-scale electron-density fluctuations. Eventually, namely this nonuniform distribution
of small-scale electron-density fluctuations leads to the specific multifractal structure of the amplitude records of received
signals.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 4, pp. 287–294, April 2008. 相似文献
3.
We consider the problem of diagnostics of the local structure of small-scale ionospheric turbulence using the multifractal
analysis of received signals from the Earth’s orbital satellites after the radio sounding of the inhomogeneous ionosphere
by these signals. In particular, it is shown that analysis of the multifractal structure of the received-signal amplitude
records by the method of multidimensional structural functions allows one to determine the indices of the multipower local
spectra of the small-scale ionospheric turbulence, which are inherent in it due to the nonuniform spatial distribution of
small-scale fluctuations of the electron number density. It is noted that information on the multipower spectrum of small-scale
ionospheric turbulence is not available for the conventional radio scintillation method based on the classical spectral analysis
of received signals during the remote radio sounding of the ionosphere. At the same time, the method of multidimensional structural
functions is efficient under conditions of actual nonstationarity of the process of scattering of the HF radio waves by the
randomly inhomogeneous ionospheric plasma. The method of multidimensional structural functions is used for the multifractal
processing of received signals of orbital satellites during special experiments on radio sounding of the midlatitude ionosphere
under natural conditions and its modification by high-power HF radio waves. First data on the indices of the multipower local
spectra of small-scale ionospheric turbulence are obtained.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 52, No. 1, pp. 14–22, January 2009. 相似文献
4.
We present the results of the studies of fractal properties of the small-scale inhomogeneities of traveling ionospheric disturbances
in special experiments on radio-raying of the midlatitude ionosphere by signals from orbital satellites in 2004–2006. Along
with the conventional correlation processing of the received signals, we performed their multifractal analysis, as well as
fractal processing of signals by the correlation-integral method. Important information on fractal properties of the small-scale
turbulence for the least studied part of the upper-ionosphere inhomogeneity spectrum in the interval of characteristic scales
l ≈ 1–10 km is obtained. In particular, it is noted that the fractal structure of these inhomogeneities can be originated
from the nonlinear “destruction” of several large-scale sinusoidal structures in a quasistable traveling disturbance. It is
also noted that the multifractal spectra of amplitude fluctuations of the received signals obtained in the experiments in
different years, in different time of the day, and in different seasons of the observations are quite similar. This is evidence
that intermittency is a universal property of the plasma turbulence, at least for the midlatitude upper ionosphere.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 1, pp. 22–30, January 2008. 相似文献
5.
V. A. Alimov F. I. Vybornov E. N. Myasnikov A. V. Rakhlin 《Radiophysics and Quantum Electronics》2008,51(11):874-879
We show the results of the first experimental studies of the multifractal structure of the developed artificial ionospheric
turbulence. As a result of the special multifractal analysis of the recorded amplitudes of signals from the orbital satellites,
which were obtained during the experiments on radio tomography of the irregularities excited in the ionosphere by the powerful
mid-latitude heating facility “Sura,” it is found that the characteristic multifractal structure of these records is caused
by the nonuniform spatial distribution of the small-scale fluctuations of the electron number density in the artificial irregularities
of the ionospheric plasma. Comparative analysis is performed for the multifractal spectra of fluctuations of both the amplitudes
and energies of signals received from the orbital satellites upon radio transmission probing of the region of artificial ionospheric
turbulence by these signals at three observation points located near the “Sura” heating facility and spaced apart to a distance
of about 100–150 km.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 11, pp. 970–976, November 2008. 相似文献
6.
We consider the problem of relating the local structure of small-scale ionospheric turbulence to the measured frequency-spectrum
indices and fractal dimensions of amplitude records of the signals received on the Earth during remote sensing of the ionosphere
onboard the satellites. It is shown that knowledge of these parameters permits one to determine the true values of the local-spectrum
indices of the electron-density fluctuations for isotropic small-scale turbulence of the ionosphere both under natural conditions
and during its modification by high-power short-wave radiation as well as to specify fractal dimensions of space filled by
small-scale irregularities of the turbulent structures in the ionosphere. We show the necessity of detailed experimental studies
of the fractal properties of small-scale ionospheric irregularities of both natural and artificial origin by using a multifractal
analysis in combination with the synchronous correlation processing of received signals during remote sensing of the ionosphere.
This will give important information on the local structure of small-scale ionospheric turbulence inaccessible for studies
within the framework of the classical method of radio scintillation.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 4, pp. 300–308, April 2007. 相似文献
7.
V. A. Alimov F. I.Vybornov E. N. Myasnikov A. V. Rakhlin V. L. Frolov 《Radiophysics and Quantum Electronics》2009,52(9):609-617
We present the results of the experiment on studying the multifractal structure (with inhomogeneity sizes from tens to hundreds
of meters across the Earth’s magnetic field) of the artificial ionospheric turbulence when the midlatitude ionosphere is affected
by high-power HF radio waves. The experimental studies were performed on the basis of the “Sura” heating facility with the
help of radio sounding of the disturbed region of the ionospheric plasma by signals from the Earth’s orbital satellites. The
influence of the magnetic zenith effect on measured multifractal characteristics of the small-scale artificial turbulence
of the midlatitude ionosphere was examined. In the case of vertical radio sounding of the disturbed ionosphere region, the
measured multipower and generalized multifractal spectra of turbulence coincide well with similar multifractal characteristics
of the ionospheric turbulence under natural conditions. This result is explained by the fact that the scattering of signals
by weak quasi-isotropic small-scale inhomogeneities of the electron number density in a thick layer with a typical size of
several hundred kilometers above the region of reflection of high-power HF radio waves gives the major contribution to the
observed amplitude fluctuations of received signals. In the case of oblique sounding of the disturbance region at small angles
between the line of sight to the satellite and the direction of the Earth’s magnetic field, the nonuniform structure of the
small-scale turbulence with a relatively narrow multipower spectrum and small variations in the generalized multifractal spectrum
of the electron number density was detected. Such a fairly well ordered structure of the turbulence is explained by the influence
of the magnetic zenith effect on the generation of anisotropic small-scale artificial turbulence in a thin layer having a
typical size of several ten kilometers and located below the pump-wave reflection height in the upper ionosphere. 相似文献
8.
We report on the results of the first special experiment on radio sounding of the midlatitude ionosphere by signals from in-orbit
satellites at a frequency of 150 MHz under quiet geophysical conditions. Along with the conventional correlation processing,
fractal processing of the received signals was also performed. Using the fractal approach, we obtained first data on the sources
and generation mechanisms of small-scale plasma inhomogeneities of the traveling ionospheric disturbances (TIDs) in the upper
ionosphere. It is noted that the phenomenon of nonlinear “ breaking” of the acoustic-gravity waves entering the ionosphere
from the underlying atmosphere plays the crucial role in the formation of plasma inhomogeneities of the TIDs.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 7, pp. 561–569, July 2006. 相似文献
9.
We consider various theoretical models for the spectrum of small-scale ionospheric turbulence. The particular role of the
generalized model of the ionospheric-turbulence spectrum, which takes into account that the anisotropy (extension) of small-scale
irregularities of the upper ionosphere along the Earth's magnetic field direction depends on the transverse scale of those
irregularities, is emphasized. The results of the. rst target experiments on radio sensing of the midlatitude ionosphere by
signals from on-orbit satellites at frequencies 150 and 400 MHz under conditions of increased solar activity are presented.
The experiments were performed at the radiophysical facility in the Nizhny Novgorod region in 2003. We studied statistical
characteristics of the amplitude fluctuations of the received signals for different angles ϑ between the line of sight from
a satellite to a ground-based reception point and the Earth's magnetic field direction. It was found in the course of the
experiments that the spectrum slope of amplitude fluctuations of the received radiation is a function of the angle ϑ. The
obtained result agrees with the generalized model of the ionospheric-turbulence spectrum and can be an argument in favor of
the pronounced anisotropic structure of small-scale electron-density irregularities of the midlatitude ionosphere under disturbed
geophysical conditions.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 5, pp. 382–387, May 2005. 相似文献
10.
Using the method of radio sounding of the mid-latitude ionosphere by the satellite signals, we study the multifractal structure
of small-scale ionospheric turbulence during a solar eclipse. The measured multipower and generalized multifractal spectra
of small-scale ionospheric turbulence at the initial and closing stages of the eclipse turn out to be almost identical on
the space radio paths with different orientations. This is indicative of a sufficiently high stability of the nonuniform spatio-temporal
distribution of small-scale fluctuations of the ionospheric electron number density under conditions of geophysical disturbances
due to global physical processes in the ionospheric plasma during a solar eclipse.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 52, No. 4, pp. 302–306, April 2009. 相似文献
11.
We consider the problem of obtaining reliable values of the local-spectrum indices of the electron number density fluctuations
for small-scale ionospheric turbulence. It is shown that the use of a multifractal analysis in combination with the synchronous
correlation processing of the received signals in the experiments on remote radio sounding of the ionosphere by satellite
signals permits one to solve the posed problem. In this case, the true values of the local-spectrum indices of small-scale
ionospheric turbulence, which are measured in such specialized experiments under natural conditions and during modification
of the ionosphere by high-power HF radio emission, can differ notably from their standard values obtained within the framework
of the classical method of radio scintillations, in which only correlation processing of the data is used.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 7, pp. 571–574, July 2008. 相似文献
12.
V. A. Alimov L. M. Erukhimov E. N. Myasnikov A. V. Rakhlin 《Radiophysics and Quantum Electronics》1997,40(4):294-300
The problem of defining the spectral form of ionospheric irregularities with dimensions from hundreds to thousands of meters
is considered. A generalized model is proposed for the ionospheric turbulence spectrum, taking into account both the anisotropic
properties of the large-scale fraction of irregularities and the dependence of the anisotropy (elongation) of small-scale
irregularities of the upper ionosphere along the Earth magnetic field direction on the transverse scale of those irregularities.
Relations have been derived to determine the basic parameters of the irregularity spectrum of the uppers ionosphere (anisotropy
indices for large-scale and small-scale fractions) and the depth of a thin ionospheric layer through measurement of the spectral
characteristics of amplitude and phase fluctuations of orbital satellite signals. Using this model of the plasma irregularity
spectrum, we can explain consistently many well-known experimental data on spectral characteristics of the phase and amplitude
fluctuations of orbital satellite signals both in the high-latitude and midlatitude ionosphere.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 40, No. 4, pp. 446–456, April, 1997. 相似文献
13.
É. L. Afraimovich É. I. Astafieva S. V. Voeykov 《Radiophysics and Quantum Electronics》2006,49(2):79-92
Using the technique of global detection of ionospheric disturbances, based on processing the data of the global GPS-receiver
network, we obtain experimental proof of the existence of a solitary wave (soliton) in the atmosphere during the main phase
of the major magnetic storm of October 30, 2003. The soliton with a characteristic duration of about 40 min and a relative
amplitude of up to 40%, originated at the moment of the maximum disturbance of the Earth’s magnetic field, traveled without
changing its shape at a distance of up to 4500 km with a velocity of 1400 m/s, which exceeded the atmospheric sound velocity
at the heights of the main electron-density maximum in the ionosphere (about 300 km) by a factor of 1.5. The intensity of
variations in the total electron content in the period range 1–10 min increases by an order of magnitude as the soliton propagates
from the North-East to the South-West of the USA in the regions with the maximum amplitude of the large-scale disturbance.
This corresponds to enhancement of ionospheric irregularities with scales from 10 to 100 km, and also of small-scale irregularities
(SSI) with scales of 100 to 1000 m, since the spectrum of the ionospheric irregularities has a power-law shape. Spatio-temporal
characteristics of the density distribution of phase slips of GPS signals are close to the corresponding characteristics of
the SSI intensity. This agrees with the existing concept that the phase slips result from scattering of GPS radio signals
by SSIs. Both the SSI amplitude and the density of phase slips decrease as the soliton decays in amplitude.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 2, pp. 89–104, February 2006. 相似文献
14.
Using the method of parabolic equation (MPE), we obtain transfer equations for the mean field, the space-coherence function,
and the ray intensity of a radiowave beam as it is reflected from a plasma layer with random inhomogeneities. The general
solutions of these equations are found. Special attention is given to the case of radiowave beam reflection from a linear
plasma layer with large-scale electron-density inhomogeneities. If a weakly directed transceiving SW antenna is used, the
shortwave scattering can lead to a pronounced (of the order of 3 dB) decrease in the intensity of a vertical-sounding signal
reflected from the ionospheric F2 layer only under the conditions of abnormally strong ionospheric electron-density perturbations.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 41, No. 8, pp. 955–965, August, 1998. 相似文献
15.
V. A. Alimov F. I. Vybornov L. M. Erukhimov G. P. Komrakov N. A. Mityakov A. V. Rakhlin 《Radiophysics and Quantum Electronics》1997,40(6):456-458
We show some results of experiments on synchronous sounding of the ionosphere by short-wave signals at the Radiophysical Research
Institute’s test site in Zimenki and Vasil’sursk, Nizhniy Novgorod province, during ionospheric modification by high-power
short radiowaves from transmitters of the “Sura” facility in Vasil’sursk. In the course of experiments we proved directly
the decisive role of large-scale inhomogeneities of the ionospheric plasma with dimensions of from several kilometers to several
dozens of kilometers in the formation of artificial F- spread. The small-scale inhomogeneities with dimensions smaller than
1 km, which are localized in a relatively thin layer near the reflection level of a high-power short radiowave, emerged only
at sounding waves, propagating (reflected) in the immediate vicinity of the center of the heating region.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 40, No. 6, pp. 688–692, June, 1997. 相似文献
16.
V. P. Uryadov G. G. Vertogradov V. G. Vertogradov S. V. Kubatko A. A. Ponyatov Yu. N. Cherkashin I. V. Krasheninnikov V. A. Valov G. P. Komrakov A. V. Makarov D. V. Bredikhin 《Radiophysics and Quantum Electronics》2009,52(4):241-251
We describe the operation of an ionosonde/position finder with chirp modulation of the signal. The first results of measuring
the characteristics of short-wave radio signals scattered by artificial small-scale inhomogeneities, which were obtained by
means of an ionosonde/position finder on the IZMIRAN—“SURA”—Rostov-on-Don path are presented. It was found that under certain
ionospheric conditions, the angular and frequency selection of the scattered signals take place, in which case the signals
are observed simultaneously in several frequency intervals (mainly, in three, namely, 6–9.5 MHz, 10–12 MHz, and 15–18 MHz)
with different angles of incidence of radio waves in the vertical plane. In this case, the incidence angles were 20◦–35◦,
18◦–32◦, and 10◦–20◦ from the horizon for the first, second, and third frequency interval, respectively. Ionograms of oblique
sounding were modeled allowing for the scattering of radio waves by artificial small-scale inhomogeneities. It is shown that
at frequencies from 10 to 12 MHz, aspect conditions are fulfilled for the signals ducting along the high-angle beam (Pedersen
mode). At frequencies 15–18 MHz (higher than the maximum observable frequency of the forward signal on the path IZMIRAN—Rostov-on-Don),
aspect scattering conditions are fulfilled for the signals incident on a scattering area in the ascending part of the trajectory.
At low frequencies 6–9.5 MHz (below the maximum observed frequency of the forward signal on the IZMIRAN—Rostov-on-Don path),
the observable additional signals are caused by the scattering of radio waves by artificial inhomogeneities with subsequent
relfection of the scattered signal from the Earth on the “SURA”—Rostov-on-Don path.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 52, No. 4, pp. 267–278, April 2009. 相似文献
17.
S. M. Mukhamedin 《Russian Physics Journal》2011,54(1):28-31
Fraktal theory allows specifics of turbulence inhomogeneities of different types to be considered in the spectral theory of
self-affine multifractals. Experiments demonstrate that the turbulence possesses the multifractal properties. Nowadays the
multifractal analysis is widely used in various branches of modern physics. The structural elements of the homogeneous and
isotropic turbulence – vortices – represent a self-similar multifractal with the same similarity coefficient for all spatial
variables. 相似文献
18.
A. V. Tolmacheva N. V. Bakhmet’eva V. D. Vyakhirev V. N. Bubukina E. E. Kalinina 《Radiophysics and Quantum Electronics》2011,54(6):365-375
We present the results of measuring the electron number density in the ionospheric E layer by a method based on the creation of artificial periodic irregularities of the ionospheric plasma with two different
spatial scales. Artificial periodic irregularities were created by the radiation of the Sura heating facility at frequencies
4.7 and 5.6 MHz. The electron number density was determined by the ratio of relaxation times of the signals backscattered
by artificial periodic irregularities during their sounding by probing radio waves at the mentioned frequencies. Features
of the electron-density profiles obtained in 2006 and 2007 in the altitude range 95–115 km are discussed and their altitude–time
variations are analyzed. 相似文献
19.
We present the results of analysis of the spectra of amplitude scintillations at a frequency of 150 MHz and a difference phase
at frequencies of 150 and 400 MHz, which were obtained in the experiment on radio tomography of artificial ionospheric turbulence
(AIT) excited by the mid-latitude high-power “Sura” heating facility [1]. We used the data on radio probing of the AIT region
at a frequency of 150 MHz by signals from artificial satellites in near-polar circular orbits at altitudes of 1000 km above
the Earth’s surface. The signals were received simultaneously at three spaced apart points located at distances of about 100–150
km from each other along the projection of the satellite trajectory onto the Earth’s surface. The analysis of the data shows
that in the range of scales smaller than 0.5–1.0 km across the geomagnetic field, the AIT spatial spectrum can be described
by the power-law function with the spectral index p⊥ = 1.7–2.5. For irregularities with the same transverse scales, the spectral index in the direction of the magnetic field
amounts to p‖ = 5–7.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 8, pp. 722–730, August 2007 相似文献
20.
P. N. V’yugin V. G. Gavrilenko L. M. Kustov A. I. Mart’yanov M. B. Nechaeva 《Radiophysics and Quantum Electronics》2007,50(2):87-94
We consider the interferometer method by which a turbulent water flow is remotely studied by sounding with a noise ultrasound
signal. It is shown that the processing of signals received by two spatially separated receivers makes it possible to extract
the signal phase difference caused by the concentration fluctuations of cavity air bubbles on the propagation paths. Spectral
analysis of the random phase difference permitted diagnostics of the propagation medium. In particular, it is shown that the
output signal of the interferometer carries information on the spatial spectrum of parameter fluctuations of the medium, and
on the velocity of inhomogeneities if the interferometer base is parallel to the turbulent flow.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 2, pp. 95–103, February 2007. 相似文献