Vector solution for the mean electromagnetic fields in a layer of random particles

Radio Science ◽  
1986 ◽  
Vol 21 (5) ◽  
pp. 771-786 ◽  
Author(s):  
R. H. Lang ◽  
S. S. Seker ◽  
D. M. LeVine
Keyword(s):  
Electromagnetic Fields ◽  
Vector Solution ◽  
The Mean

scholarly journals Personal Exposure Assessment to Wi-Fi Radiofrequency Electromagnetic Fields in Mexican Microenvironments

2021 ◽  
Vol 18 (4) ◽  
pp. 1857
Author(s):  
Raquel Ramirez-Vazquez ◽  
Jesus Gonzalez-Rubio ◽  
Isabel Escobar ◽  
Carmen del Pilar Suarez Rodriguez ◽  
Enrique Arribas
Keyword(s):  
Risk Perception ◽  
Electromagnetic Fields ◽  
Personal Exposure ◽  
Wireless Internet ◽  
European Cities ◽  
Radiofrequency Electromagnetic Fields ◽  
Time Period ◽  
The Mean ◽  
Personal Exposure Assessment ◽  
Study Participants

In recent years, personal exposure to Radiofrequency Electromagnetic Fields (RF-EMF) has substantially increased, and most studies about RF-EMF with volunteers have been developed in Europe. To the best of our knowledge, this is the first study carried out in Mexico with personal exposimeters. The main objective was to measure personal exposure to RF-EMF from Wireless Fidelity or wireless Internet connection (Wi-Fi) frequency bands in Tamazunchale, San Luis Potosi, Mexico, to compare results with maximum levels permitted by international recommendations and to find if there are differences in the microenvironments subject to measurements. The study was conducted with 63 volunteers in different microenvironments: home, workplace, outside, schools, travel, and shopping. The mean minimum values registered were 146.5 μW/m2 in travel from the Wi-Fi 2G band and 116.8 μW/m2 at home from the Wi-Fi 5G band, and the maximum values registered were 499.7 μW/m2 and 264.9 μW/m2 at the workplace for the Wi-Fi 2G band and the Wi-Fi 5G band, respectively. In addition, by time period and type of day, minimum values were registered at nighttime, these values being 129.4 μW/m2 and 93.9 μW/m2, and maximum values were registered in the daytime, these values being 303.1 μW/m2 and 168.3 μW/m2 for the Wi-Fi 2G and Wi-Fi 5G bands, respectively. In no case, values exceeded limits established by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Of the study participants (n = 63), a subgroup (n = 35) answered a survey on risk perception. According to these results, the Tamazunchale (Mexico) population is worried about this situation in comparison with several European cities; however, the risk perception changes when they are informed about the results for the study.

scholarly journals THE FOCUSING OF VACUUM FLUCTUATIONS

2002 ◽  
Vol 17 (29) ◽  
pp. 4393-4402
Author(s):  
L. H. FORD ◽  
N. F. SVAITER
Keyword(s):  
Energy Density ◽  
Electric Field ◽  
Electromagnetic Fields ◽  
Electric Fields ◽  
Negative Energy ◽  
Parabolic Mirror ◽  
Vacuum Fluctuations ◽  
Negative Energy Density ◽  
Cylindrical Mirror ◽  
The Mean

The quantization of the scalar and electromagnetic fields in the presence of a parabolic mirror is developed in the context of a geometric optics approximation. We calculate the mean squared scalar and electric fields near the focal line of a parabolic cylindrical mirror. These quantities are found to grow as inverse powers of the distance from the focus. We give a combination of analytic and numerical results for the mean squared fields. In particular, we find that the mean squared electric field can be either negative or positive, depending upon the choice of parameters. The case of a negative mean squared electric field corresponds to a repulsive Van der Waals force on an atom near the focus, and to a region of negative energy density. Similarly, a positive value corresponds to an attractive force and a possibility of atom trapping in the vicinity of the focus.

ENTANGLEMENT AND PHOTON DYNAMICS IN THE INTERACTION BETWEEN TWO QUANTIZED ELECTROMAGNETIC FIELDS AND 3-LEVEL ATOMS

2011 ◽  
Vol 09 (01) ◽  
pp. 593-605 ◽  
Author(s):  
B. VASEGHI ◽  
G. REZAEI ◽  
R. KHORDAD ◽  
A. FALLAH ZADEH
Keyword(s):  
Coherent State ◽  
Electromagnetic Fields ◽  
Atomic System ◽  
Single Mode ◽  
The Other ◽  
Level Atom ◽  
Number State ◽  
Fock State ◽  
The Mean ◽  
Degree Of Entanglement

We study in this paper the dynamics of two electromagnetic (EM) fields and their entanglement in the interaction with a 3-level atom (Λ-configuration). We investigate the interaction when initially one of the fields is in a single mode coherent state, and the other one is in a Fock(number) state. We have calculated the mean photon numbers of the fields and their entanglement by means of the fields entropy as a measure of it. The results show the synchronization between entanglement beats and collapses-revivals of the fields, which cause the field in the Fock state (noncoherent) to behave coherently during the interaction. Also the results offer a way to generate coherent fields and achieve any desired degree of entanglement with specified dynamics via controlling the parameters of the atomic system.

scholarly journals CALCULATION OF ELECTROMAGNETIC FIELDS, FORCES AND TEMPERATURE IN A FINITE CYLINDER

2002 ◽  
Vol 7 (1) ◽  
pp. 21-32
Author(s):  
A. Buikis ◽  
H. Kalis
Keyword(s):  
Electromagnetic Fields ◽  
Original Method ◽  
Finite Cylinder ◽  
Symmetric System ◽  
Axially Symmetric ◽  
Azimuthal Component ◽  
Electromagnetic Forces ◽  
Mean Values ◽  
Three Phase ◽  
The Mean

The distribution of electromagnetic fields, forces and temperatures induced by a three‐phase axially‐symmetric system of electric current in a conducting cylinder of a finite length has been calculated. An original method was used to calculate the radial and axial components of the magnetic fields and the mean values of electromagnetic forces, as well as the azimuthal component of the electric field and of the mean curl of the electromagnetic forces. For finding the source term in the temperature equation we applied an approximation of the heat transport problem based on the finite‐difference method. Such a procedure allows one to calculate the distribution of temperatures inside the cylinder depending on that of currents in the wires.

Photo-electric Hβ and uvby photometry

1966 ◽  
Vol 24 ◽  
pp. 170-180
Author(s):  
D. L. Crawford
Keyword(s):  
Narrow Band ◽  
Line Strength ◽  
Interference Filter ◽  
B Stars ◽  
Relative Line ◽  
The Mean ◽  
F Stars ◽  
Two Parameters ◽  
Filter Photometry ◽  
The Continuum

Early in the 1950's Strömgren (1, 2, 3, 4, 5) introduced medium to narrow-band interference filter photometry at the McDonald Observatory. He used six interference filters to obtain two parameters of astrophysical interest. These parameters he calledlandc, for line and continuum hydrogen absorption. The first measured empirically the absorption line strength of Hβby means of a filter of half width 35Å centered on Hβand compared to the mean of two filters situated in the continuum near Hβ. The second index measured empirically the Balmer discontinuity by means of a filter situated below the Balmer discontinuity and two above it. He showed that these two indices could accurately predict the spectral type and luminosity of both B stars and A and F stars. He later derived (6) an indexmfrom the same filters. This index was a measure of the relative line blanketing near 4100Å compared to two filters above 4500Å. These three indices confirmed earlier work by many people, including Lindblad and Becker. References to this earlier work and to the systems discussed today can be found in Strömgren's article inBasic Astronomical Data(7).

A one-dimensional self-gravitating stellar gas

1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar
Keyword(s):  
Gravitational Field ◽  
Phase Space ◽  
Motion Picture ◽  
Space Distribution ◽  
Two Dimensional ◽  
One Dimensional ◽  
Phase Space Distribution ◽  
Dimensional Phase Space ◽  
The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

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.

On nearly-commensurable periods in the restricted problem of three bodies, with calculations of the long-period variations in the interior 2:1 case

1966 ◽  
Vol 25 ◽  
pp. 197-222 ◽  
Author(s):  
P. J. Message
Keyword(s):  
Periodic Solution ◽  
Periodic Solutions ◽  
Large Amplitude ◽  
Restricted Problem ◽  
Small Amplitude ◽  
Minor Planets ◽  
Long Period ◽  
Numerical Integrations ◽  
Period Variations ◽  
The Mean

An analytical discussion of that case of motion in the restricted problem, in which the mean motions of the infinitesimal, and smaller-massed, bodies about the larger one are nearly in the ratio of two small integers displays the existence of a series of periodic solutions which, for commensurabilities of the typep+ 1:p, includes solutions of Poincaré'sdeuxième sortewhen the commensurability is very close, and of thepremière sortewhen it is less close. A linear treatment of the long-period variations of the elements, valid for motions in which the elements remain close to a particular periodic solution of this type, shows the continuity of near-commensurable motion with other motion, and some of the properties of long-period librations of small amplitude.To extend the investigation to other types of motion near commensurability, numerical integrations of the equations for the long-period variations of the elements were carried out for the 2:1 interior case (of which the planet 108 “Hecuba” is an example) to survey those motions in which the eccentricity takes values less than 0·1. An investigation of the effect of the large amplitude perturbations near commensurability on a distribution of minor planets, which is originally uniform over mean motion, shows a “draining off” effect from the vicinity of exact commensurability of a magnitude large enough to account for the observed gap in the distribution at the 2:1 commensurability.

the effects of resonance with Jupiter in the system of short-period comets

1974 ◽  
Vol 22 ◽  
pp. 193-203
Author(s):  
L̆ubor Kresák
Keyword(s):  
Structural Effects ◽  
Order Resonance ◽  
Mean Motion ◽  
Short Period ◽  
The Mean ◽  
Compound Effect ◽  
Low Order

AbstractStructural effects of the resonance with the mean motion of Jupiter on the system of short-period comets are discussed. The distribution of mean motions, determined from sets of consecutive perihelion passages of all known periodic comets, reveals a number of gaps associated with low-order resonance; most pronounced are those corresponding to the simplest commensurabilities of 5/2, 2/1, 5/3, 3/2, 1/1 and 1/2. The formation of the gaps is explained by a compound effect of five possible types of behaviour of the comets set into an approximate resonance, ranging from quick passages through the gap to temporary librations avoiding closer approaches to Jupiter. In addition to the comets of almost asteroidal appearance, librating with small amplitudes around the lower resonance ratios (Marsden, 1970b), there is an interesting group of faint diffuse comets librating in characteristic periods of about 200 years, with large amplitudes of about±8% in μ and almost±180° in σ, around the 2/1 resonance gap. This transient type of motion appears to be nearly as frequent as a circulating motion with period of revolution of less than one half that of Jupiter. The temporary members of this group are characteristic not only by their appearance but also by rather peculiar discovery conditions.

Contrast of Filament Bright Rims

1994 ◽  
Vol 144 ◽  
pp. 365-367
Author(s):  
E. V. Kononovich ◽  
O. B. Smirnova ◽  
P. Heinzel ◽  
P. Kotrč
Keyword(s):  
High Altitude ◽  
Line Profile ◽  
Line Center ◽  
Magnetic Structures ◽  
The Mean

AbstractThe Hα filtergrams obtained at Tjan-Shan High Altitude Observatory near Alma-Ata (Moscow University Station) were measured in order to specify the bright rims contrast at different points along the line profile (0.0; ± 0.25; ± 0.5; ± 0.75 and ± 1.0 Å). The mean contrast value in the line center is about 25 percent. The bright rims interpretation as the bases of magnetic structures supporting the filaments is suggested.

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