Radio Channel of Through-the-Earth Communication Fitted for the Subway Condition

2016 ◽  
pp. 539-545
Author(s):  
Zeng Jiajia ◽  
Su Zhong
Keyword(s):  
Radio Channel ◽  
The Earth

scholarly journals Parametric Method for Searching Subsurface Objects Based on the Interaction of Seismic and Electromagnetic Waves

2019 ◽  
pp. 987-997
Author(s):  
Evgeniy N. Garin ◽  
Roman G. Shaydurov
Keyword(s):  
Phase Shift ◽  
Electromagnetic Waves ◽  
Seismic Waves ◽  
Radio Channel ◽  
Parametric Method ◽  
Binding Parameters ◽  
The Earth ◽  
Air Interface ◽  
Mathematical Processing ◽  
Seismic Impacts

The physical basis of the method for detecting subsurface objects in the earth is described on the basis of excitation of the Rayleigh shock seismic waves along the earth-air interface and registration by the radar method of the Doppler phase shift arising under the action of seismic impacts of vibrations of the search object body. The energy dependencies for the radar channel are estimated, the binding parameters of the seismic emitter and the radio channel are given. The results of experimental work and mathematical processing of the data are presented

scholarly journals Statistical characteristics of geomagnetic storm activity during solar cycle 24, 2009–2020

2020 ◽  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Geomagnetic Field ◽  
Geomagnetic Storms ◽  
Radio Channel ◽  
Statistical Characteristics ◽  
The Earth ◽  
Solar Cycle 24 ◽  
Cycle 24

Urgency. The atmosphere and geospace are widely used as a radio channel in solving problems of radar, radio navigation, direction finding, radio communication, radio astronomy, and the remote sensing of the Earth from space or the near-earth environment from the surface of the planet. The parameters of the atmospheric-space radio channel are determined by the state of tropospheric and space weather, which is formed mainly by non-stationary processes on the Sun (solar storms) and partly by high-energy processes on the Earth and in the atmosphere. Geospace storms give rise to the strongest disturbances of the atmospheric-space radio channel, and it is important to note that these storms are diverse, so that no two storms are alike. At the same time, storms have both similar and individual features. Currently, there is insufficient knowledge about both of these features, and their study remains an urgent task of space geophysics and space radio physics. In particular, the identification of general patterns is advisable by performing a statistical analysis of a large number of storms. The aim of this work is to statistically analyze the parameters of the solar wind and geomagnetic field during the Solar Cycle 24 activity (2009–2020). Methods and Methodology. The parameters of the disturbed solar wind (number density nsw, velocity Vsw, and temperature Tsw), the disturbed values of the By- and Bz-components of the interplanetary magnetic field, which is the cause of magnetic storms on Earth, as well as the indices of geomagnetic activity (AE, Dst and Kp) are selected as source input to the study. In this paper, geomagnetic storms with Kр ≥ 5 or G1, G2, G3, and G4 geomagnetic storms are considered. In total, there were 153 storms with Kp ≥ 5. The time series of the nsw, Vsw, Tsw maximum values, of the By- and Bz-components, and of the AE, Dst and Kp indices, as well as of the Bz-component and the Dst index minimum values have been analyzed. Results. The main statistical characteristics of the parameters of the solar wind, interplanetary magnetic field, and of the geomagnetic field have been determined for 153 events that took place during Solar Cycle 24. Conclusions. The geomagnetic situation during Solar Cycle 24 was calmer than during Solar Cycle 23.

The motion of a lunar orbiter

1966 ◽  
Vol 25 ◽  
pp. 373
Author(s):  
Y. Kozai
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Artificial Satellite ◽  
Equations Of Motion ◽  
Triaxial Ellipsoid ◽  
The Moon ◽  
Secular Motion ◽  
The Earth ◽  
Close Satellite ◽  
The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Origin of the Moon

1962 ◽  
Vol 14 ◽  
pp. 149-155 ◽  
Author(s):  
E. L. Ruskol
Keyword(s):  
Chemical Composition ◽  
Solar System ◽  
The Moon ◽  
The Earth ◽  
The Difference ◽  
Origin Of The Moon

The difference between average densities of the Moon and Earth was interpreted in the preceding report by Professor H. Urey as indicating a difference in their chemical composition. Therefore, Urey assumes the Moon's formation to have taken place far away from the Earth, under conditions differing substantially from the conditions of Earth's formation. In such a case, the Earth should have captured the Moon. As is admitted by Professor Urey himself, such a capture is a very improbable event. In addition, an assumption that the “lunar” dimensions were representative of protoplanetary bodies in the entire solar system encounters great difficulties.

The Origin of the Moon and its Relationship to the Origin of the Solar System

1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey
Keyword(s):  
Solar System ◽  
The Moon ◽  
The Past ◽  
The Earth ◽  
Short Period ◽  
Origin Of The Moon

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.

Probable Structure and Nature of the Formations on the Reverse Side of the Moon According to Photometric Measurements of Lunar Photographs

1962 ◽  
Vol 14 ◽  
pp. 39-44
Author(s):  
A. V. Markov
Keyword(s):  
The Moon ◽  
Probable Structure ◽  
The Earth ◽  
Interplanetary Station ◽  
Photometric Measurements ◽  
Automatic Interplanetary Station

Notwithstanding the fact that a number of defects and distortions, introduced in transmission of the images of the latter to the Earth, mar the negatives of the reverse side of the Moon, indirectly obtained on 7 October 1959 by the automatic interplanetary station (AIS), it was possible to use the photometric measurements of the secondary (terrestrial) positives of the reverse side of the Moon in the experiment of the first comparison of the characteristics of the surfaces of the visible and invisible hemispheres of the Moon.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

Statistical results on discovered near-Earth asteroids

1999 ◽  
Vol 173 ◽  
pp. 81-86
Author(s):  
S. Berinde
Keyword(s):  
Dynamical Evolution ◽  
Minor Planet ◽  
Orbital Elements ◽  
The Earth ◽  
Near Earth Asteroids ◽  
Statistical Results

AbstractThe first part of this paper gives a recent overview (until July 1st, 1998) of the Near-Earth Asteroids (NEAs) database stored at Minor Planet Center. Some statistical interpretations point out strong observational biases in the population of discovered NEAs, due to the preferential discoveries, depending on the objects’ distances and sizes. It is known that many newly discovered NEAs have no accurately determinated orbits because of the lack of observations. Consequently, it is hard to speak about future encounters and collisions with the Earth in terms of mutual distances between bodies. Because the dynamical evolution of asteroids’ orbits is less sensitive to the improvement of their orbital elements, we introduced a new subclass of NEAs named Earth-encounter asteroids in order to describe more reliably the potentially dangerous bodies as impactors with the Earth. So, we pay attention at those asteroids having an encounter between their orbits and that of the Earth within 100 years, trying to classify these encounters.

On Variations in the Chandler Frequency

1972 ◽  
Vol 1 ◽  
pp. 77-85
Author(s):  
H.J.M. Abraham ◽  
J.N. Boots
Keyword(s):  
Axis Of Rotation ◽  
The Earth ◽  
Actual Motion ◽  
Chandler Frequency

This paper suggests that some of the reported changes in the Chandler frequency are associated with inelastic changes in the Earth. There has been controversy as to how much of the apparent secular polar drift is due to actual motion of the axis of rotation within the Earth, and how much it is merely the reflection of movements by certain observatories. Therefore, when more southern data are available it will be interesting to see whether similar results are obtained.

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