共查询到20条相似文献,搜索用时 31 毫秒
1.
L. M. Erukhimov A. A. Ponyatov V. P. Uryadov V. A. Ivanov V. V. Shumaev I. B. Egorov Yu. N. Cherkashin 《Radiophysics and Quantum Electronics》1996,41(1):1-6
The results of experimental studies of the fine structure of a signal in the vicinity of the maximum observed frequency (MOF)
on the Khabarovsk—Nizhny Novgorod path of oblique chirp sounding (OCS) are presented. Additional tracks were observed in the
region between the high-angle and low-angle rays during magneto-ionospheric disturbances. Under strong disturbances the ionograms
were of a spreading type in the vicinity of the MOF. The observed effect was modelled in the presence of travelling ionospheric
disturbances (TID) with different parameters. It is shown that the stratification of the high-angle ray into several additional
tracks is a maximum for TID with vertical scales
km whose wave fronts make angles about 0–10° with the horizontal line. The possibilities of using the Pedersen mode as a
probing wave for diagnostics of the fine structure of the ionosphere in the vicinity of the F-layer maximum are discussed.
Radiophysical Research Institute, Nizhny Novgorod; State Technical University of Ioshkar-Ola, Mari Republic; Institute of
Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation, Russian Academy of Sciences, Troitsk, Moscow region, Russia.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 1, pp. 3–12, January, 1998. 相似文献
2.
G. G. Vertogradov V. G. Vertogradov V. P. Uryadov 《Radiophysics and Quantum Electronics》2006,49(12):923-936
We present the results of experimental studies of ionospheric wave-like disturbances on the basis of oblique chirp sounding
data for the mid-latitude paths Cyprus-Rostov-on-Don and Inskip-Rostov-on-Don. Twenty-four-hour measurements were performed
in January-May and October–November, 2005 and in January, 2006. The spectral analysis of variations in the maximum observed
frequency (MOF) is performed. It is shown that the spectra of the MOF fluctuations have a well pronounced line structure.
The amplitude-dominant spectral harmonics are concentrated near the frequencies 0.18–0.8 mHz (20–90-min periods). We give
the results of modeling of radio waves propagation in the presence of traveling ionospheric disturbances and compare the calculated
and experimental data.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radio.zika, Vol. 49, No. 12, pp. 1015–1029, December 2006. 相似文献
3.
L. M. Erukhimov A. A. Ponyatov V. P. Uryadov V. A. Ivanov V. V. Shumaev I. B. Egorov Yu. N. Cherkashin 《Radiophysics and Quantum Electronics》1998,41(1):1-6
The results of experimental studies of the fine structure of a signal in the vicinity of the maximum observed frequency (MOF) on the Khabarovsk—Nizhny Novgorod path of oblique chirp sounding (OCS) are presented. Additional tracks were observed in the region between the high-angle and low-angle rays during magneto-ionospheric disturbances. Under strong disturbances the ionograms were of a spreading type in the vicinity of the MOF. The observed effect was modelled in the presence of travelling ionospheric disturbances (TID) with different parameters. It is shown that the stratification of the high-angle ray into several additional tracks is a maximum for TID with vertical scales $\ell _z \sim {\text{ 20 - 40}}$ km whose wave fronts make angles about 0–10° with the horizontal line. The possibilities of using the Pedersen mode as a probing wave for diagnostics of the fine structure of the ionosphere in the vicinity of the F-layer maximum are discussed. 相似文献
4.
A. A. Ponyatov V. P. Uryadov V. A. Ivanov D. V. Ivanov A. G. Chernov V. V. Shumaev Yu. N. Cherkashin 《Radiophysics and Quantum Electronics》1999,42(4):269-277
We present the results of experimental studies of the influence of artificial ionospheric disturbances on HF signals used
for oblique sounding of the disturbed volume. The measurements have been performed by a chirp ionosonde over the path Yoshkar-Ola-“Sura”-niznhy
Novgorod with length 234 km. We found the 2F2 mode to disappear (attenuation up to 20 dB) when the ionosphere is influenced
by a vertical powerful radiation in the ordinary mode with long (15 min each) heating and pause intervals. Modeling of the
observed effect was carried out. The calculations agree well with experimental data if the traveling ionospheric disturbances
(TID) with vertical and horizontal scales lz∼20 km and lx∼50 km, respectively, and the relative disturbance of the electron density δN∼0.2–0.3 are amplified (generated) during the
ionosphere heating.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 4, pp. 303–313, April 1999. 相似文献
5.
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
6.
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
7.
Uryadov V. P. Ponyatov A. A. Rozanov S. V. Poddel'sky N. P. Poddel'sky I. N. Tsukanov A. V. 《Radiophysics and Quantum Electronics》2001,44(3):235-242
We present experimental results on HF-radiowave propagation features for the midlatitude Khabarovsk--Nizhny Novgorod and subauroral Magadan--Nizhny Novgorod paths using chirp ionospheric sounding. The spatial correlation of the maximum observed frequency (MOF) is measured. It is found that at 07:00-14:00 MSK in quiet days with a magnetic-activity index Kp 2 the correlation coefficient amounts to 0.75-0.95. With increase in disturbance for Kp 3, the correlation coefficient decreases to about 0.65-0.8. In the evening and night hours (20:00-02:00 MSK), the MOF spatial correlation decreases considerably, and reverses sign in some cases, which can be an indication of the different mechanisms of HF-signal field formation on the paths considered. Signal characteristics as functions of the path orientation relative to the ionospheric trough are analyzed. It is shown that at 20:00-02:00 MSK, the Magadan-Nizhny Novgorod path passes near the northern wall and the Khabarovsk-Nizhny Novgorod path, near the southern wall of the trough. At that time, the HF-radiation propagation was implemented through standard hop modes on the mid-latitude path and through the high-angle ray (Pedersen mode) on the subauroral path. The signal diffusivity on the Magadan-Nizhny Novgorod path exceeds by about two or three times the signal diffusivity on the Khabarovsk-Nizhny Novgorod path. The experimental data are compared with the results of simulation of the signal diffusivity due to HF-radiowave scattering by the magnetic-field-aligned ionospheric irregularities located in the vicinity of the southern boundary of the auroral oval. 相似文献
8.
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
9.
O. V. Zhuravleva A. V. Ivanov D. S. Isaev V. D. Kurnosov K. V. Kurnosov V. I. Romantsevich R. V. Chernov 《Journal of Applied Spectroscopy》2005,72(5):757-762
It is shown that superluminescent diodes rank below laser diodes in energy characteristics, but they have a wider emission
spectrum and lower noise level. The amplitude-frequency and noise characteristics of the laser diode correlate with each other,
whereas there is no such correlation for the superluminescent diode. The photon density distribution along the active area
is more homogeneous for the laser diode than for the superluminescent one.
Presented at the 5th International Scientific-Technical Conference “Quantum Electronics,” November 22–25, 2004, Minsk, Belarus.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 689–693. September–October, 2005. 相似文献
10.
Bickel T 《The European physical journal. E, Soft matter》2006,20(4):379-385
The dynamics of a tracer molecule near a fluid membrane is investigated, with particular emphasis given to the interplay between
the instantaneous position of the particle and membrane fluctuations. It is found that hydrodynamic interactions creates memory
effects in the diffusion process. The random motion of the particle is then shown to cross over from a “bulk” to a “surface”
diffusive mode, in a way that crucially depends on the elastic properties of the interface. 相似文献
11.
The propagation of electromagnetic waves in the vacuum is considered taking into account quantum fluctuations in the limits
of Maxwell-Langevin (ML) equations. For a model of “white noise” fluctuations, using ML equations, a second order partial
differential equation is found which describes the quantum distribution of virtual particles in vacuum. It is proved that
in order to satisfy observed facts, the Lamb Shift etc, the virtual particles should be quantized in unperturbed vacuum. It
is shown that the quantized virtual particles in toto (approximately 86 percent) are condensed on the “ground state” energy
level. It is proved that the extension of Maxwell electrodynamics with inclusion of the vacuum quantum field fluctuations
may be constructed on a 6D space-time continuum with a 2D compactified subspace. Their influence on the refraction indexes
of vacuum is studied. 相似文献
12.
V. O. Rapoport V. L. Frolov G. P. Komrakov G. A. Markov A. S. Belov M. Parrot J. L. Rauch 《Radiophysics and Quantum Electronics》2007,50(8):645-656
We present the results of measuring the characteristics of electromagnetic and plasma disturbances at altitudes of about 700
km, obtained by using the onboard equipment of the French microsatellite DEMETER during its passage through the magnetic tube
resting upon the region of intense generation of artificial ionospheric turbulence created due to modification of the ionospheric
F2 region by high-power radio emission from the “Sura” facility. It is shown that an artificial density duct emerging from the
disturbed region and extending to the Earth’s magnetosphere can be formed.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 8, pp. 709–721, August 2007. 相似文献
13.
Retrieval of the quasi-optimal signal activating the excitable systems using preceding noise samples
We propose a method for obtaining a signal leading to the activation of an excitable dynamic system for a signal energy close
to minimal. The efficiency of this technique, which is based on recording and processing of noise samples preceding the activation
was tested using the FitzHugh–Nagumo, Hodgkin–Huxley, and Luo–Rudy models as examples. It is shown that the proposed procedure
gives good results when the noise intensity is smaller than or close to the system activation energy. The criteria of “low”
and “high” intensities of fluctuations are proposed. The method of increasing the stability of the excitable system with respect
to “low-intensity” noise by filtering or another way of suppression of the spectral components that make the main contribution
to the energetically optimal activation signal is justified. The relation between eigenvalues of the linearized system of
the Hamiltonian equations, which describe the optimal trajectories and the activation signal, and eigenvalues of the excitable
system linearized near the initial equilibroum state is found. 相似文献
14.
O. P. Shustova N. N. Kalmykov A. V. Uryson 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(3):313-315
The composition of cosmic rays as they propagate from their source is noticeably distorted due to the photodisintegration
of nuclei against the background cosmic radiation. We analyze the propagation of different nuclei groups of ultrahigh-energy
cosmic rays on the way from their source to an earth-based facility. Two types of sources are considered: “nearby” (within
an area having a radius of ≈40 Mpc) and “remote” (at distances of hundreds of Mpc) active galactic nuclei. We show that within
the accepted model, the composition of the particles incident on the facility depends on the source type. 相似文献
15.
The differential energy spectrum of cosmic rays that is obtained on the basis of the measurements of Cherenkov radiation from
extensive air showers in an energy range of 1015–1020 eV is compared with the model of the propagation of primary particles in the interstellar medium with fractal properties.
It is found that the shape of the experimental spectrum is in good agreement with the shape of the calculated spectrum of
“all particles” at 1015–1018 eV. The average mass composition of cosmic rays that is calculated on the basis of five components does not contradict the
average mass composition obtained from the experimental data for several parameters in this energy range.
Original Russian Text ? S.P. Knurenko, A.A. Ivanov, A.V. Saburov, 2007, published in Pis’ma v Zhurnal éksperimental’noĭ i
Teoreticheskoĭ Fiziki, 2007, Vol. 86, No. 10, pp. 709–712. 相似文献
16.
17.
Yu. A. Chaikina 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(7):1061-1068
The contribution of local medium fluctuations to the rates of thermal chemical reactions was calculated for the first time.
It was shown for the “ideal gas” model that the fluctuation contribution to a rate constant was proportional to the specific
volume of particles and amounted to 1–10% already at densities of about 20 atmosphere densities. For this reason, chemical
kinetics calculations of reaction rates should be performed taking into account local medium fluctuations before taking into
account specific volume in the equation of state. 相似文献
18.
The effect of a current on spin-wave propagation in a magnet-superconductor layered structure is investigated experimentally.
The phenomenon of nonreciprocal “brightening” of the structure is observed. It is shown that this phenomenon is due to the
motion of hypervortices of magnetic flux in a Josephson medium.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 1, 49–52 (10 July 1997) 相似文献
19.
O. I. Yakovlev J. Wickert S. S. Matyugov V. A. Anufriev 《Radiophysics and Quantum Electronics》2006,49(3):167-173
We analyze ionospheric fluctuations of decimeter radio waves on occultation polar paths between the navigational GPS satellites
and the satellite CHAMP. Time dependences of the variance of the signal amplitude and amplitude fluctuation spectra under
high solar activity in October–November 2003 are presented. The behavior of the signal amplitude fluctuations during occultation
ionospheric sounding in the polar regions in different time of the day and in the equatorial regions in the daytime are considered.
Radio-wave fluctuations are related to the solar-activity manifestations. It is shown that during strong solar-flare activity,
intense small-scale plasma irregularities are excited in the polar ionosphere.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 185–193, March 2006. 相似文献
20.
S. V. Meriakri 《Technical Physics》1999,44(12):1472-1476
The propagation of a microwave pulse in a ferrite thin film-substrate structure in a regime of rereflections (“ringing”) of
the acoustic component of the substrate is studied theoretically. It is shown that as a result of the interaction of microwave
pulses with the boundaries of the substrate, propagation of a microwave excitation in this system can be regarded as a propagation
of a wave packet in a periodic nonuniform medium. The basic characteristics of a propagating wave packet are obtained.
Zh. Tekh. Fiz. 69, 82–86 (December 1999) 相似文献