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1
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Amplification of radiation in atomic vapor induced by a linearly polarized laser radiation

100%
Movsisyan M., Shmavonyan S., Papoyan A.
Open Physics
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2011
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vol. 9
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issue 4
948-955
EN
We present the results of spectroscopic and polarization studies of dilute rubidium vapor exposed to a single-frequency linearly polarized diode laser radiation in a spectral range of atomic D2 line. We report the origin of a circularly polarized radiation on V-type transitions of 87Rb F g = 2 → F e = 3 and 85Rb F g = 3 → F e = 4, and amplification of this radiation in backward direction caused by a partial population inversion among magnetic sublevels of the ground and excited levels. This is confirmed experimentally by high directivity of backward radiation, absence in its spectrum of 85Rb F g = 2 → F e = 1 (Λ-type) radiation, as well as by different nature of intensity dependences of backward and fluorescence radiations.
2
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Structural and electrical properties of KCa2Nb5O15 ceramics

88%
Behera B., Nayak P., Choudhary R.
Open Physics
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2008
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vol. 6
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issue 2
289-295
EN
A polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.
3
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Structural, dielectric, electrical and piezoelectric properties of Ba4SrRTi3V7O30 (R=Sm, Dy) ceramics

88%
Sahoo P., Panigrahi A., Patri S., Choudhary R.
Open Physics
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2008
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vol. 6
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issue 4
843-848
EN
Polycrystalline samples of Ba4SrRTi3V7O30 (R=Sm and Dy), members of the tungsten-bronze family, were prepared using a high-temperature, solid-state reaction technique and studied their electrical properties (using complex impedance spectroscopy) in a wide range of temperature (31–500°C) and frequency (1 kHz-1 MHz). Preliminary structural (XRD) analyses of these compounds show the formation of single-phase, orthorhombic structures at room temperature. The scanning electron micrographs (SEM) provided information on the quality of the samples and uniform distribution of grains over the entire surface of the samples. Detailed studies of the dielectric properties suggest that they have undergone ferroelectric-paraelectric phase transition well above the room temperatures (i.e., 432 and 355°C for R= Sm and Dy, respectively, at frequency 100 kHz). Measurements of electrical conductivity (ac and dc) as a function of temperature suggest that the compounds have semiconducting properties much above the room temperature, with negative temperature coefficient of resistance (NTCR) behavior. The existence of ferroelectricity in these compounds was confirmed from a polarization study.
4
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Evolution of the polarization of electromagnetic waves in weakly anisotropic inhomogeneous media - a comparison of quasi-isotropic approximations of the geometrical optics method and the Stokes vector formalism

88%
Kravtsov Y., Bieg B.
Open Physics
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2008
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vol. 6
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issue 3
563-568
EN
The main methods describing polarization of electromagnetic waves in weakly anisotropic inhomogeneous media are reviewed: the quasi-isotropic approximation (QIA) of geometrical optics method that deals with coupled equations for electromagnetic field components, and the Stokes vector formalism (SVF), dealing with Stokes vector components, which are quadratic in electromagnetic field intensity. The equation for the Stokes vector evolution is shown to be derived directly from QIA, whereas the inverse cannot be true. Derivation of SVF from QIA establishes a deep unity of these two approaches, which happen to be equivalent up to total phase. It is pointed out that in contrast to QIA, the Stokes vector cannot be applied for a polarization analysis of the superposition of coherent electromagnetic beams. Additionally, the ability of QIA to describe a normal modes conversion in inhomogeneous media is emphasized.
5
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Corrosion Resistance of the Nanostructured X37CrMoV5-1 Steel

75%
Skołek E., Kamiński J., Marciniak S., Świątnicki W. A., Skołek E., Kamiński J., Marciniak S., Świątnicki W. A.
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vol. 65
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issue 1
6
Publication available in full text mode
Content available

Effect of polarized signals on the performance of adaptive antenna arrays

75%
H A. K. b. A., H A. K. b. A.
Archives of Electrical Engineering
|
2020
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vol. 69
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issue 4
7
Content available remote

Contribution of superstring Z′ boson on the polarization effects in proton proton collisions

63%
Muradov R., Ahmadov A.
Open Physics
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2005
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vol. 3
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issue 3
433-455
EN
In this work we investigate the single- and the double-spin asymmetries at the collisions of polarized protons pp → (γ *, Z 0, Z′) + X within the scope of QCD, the electroweak interaction and superstring E 6 theory. The helicity amplitude method is used. Analytical expressions for the single- and the double-spin asymmetries are obtained and their dependence on the transverse momentum of the lepton pair is investigated at the three different values of invariant masses of the lepton pair. The pure contribution coming from the superstring Z′ boson on the single- and double- spin asymmetries has been extracted. The results obtained allow investigation of the spin structure of the proton.
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