281 research outputs found
Radar methods for determining the thickness of dielectric layers
This paper describes two methods, the amplitude method and the method based on geometric optics. The methods were applied to practical data obtained by georadar tests. As a result, the refractive index and thickness of the investigated planar layered medium were calculated. When using the amplitude method, the refractive index of the investigated medium is 1.3, the thickness is 0.11 m. When using the method based on geometric optics, the refractive index of the investigated medium is 1.43, the thickness is 0.102 m. After comparing the results of these methods, it was found that the error of the amplitude method is higher than that of the geometrical optics method
An algorithm for prioritizing the maintenance of power transformers
This report presents an algorithm that takes into account power transformer (PT) technical conditions and their potential for failure risk assessment to help determine maintenance precedence. The technical condition integrated index is assessed through the weighted average of condition indexes determined by the results of PT traditional and special control methods. Each control type index is the three-dimensional space vector where the coordinates are next: X - damage seriousness, Y - damage development speed, Z - damage development duration. The traditional control method defect identification and coordinate determination are carried out by an expert system without any specialist participation. Risk failure assessment includes: damages of suppliers and to consumers of electricity; transformer design features; lifetime; ES transformer unit (system) failure potential. The PT unit failure potentials were calculated using the flows of failures and damage statistics of 350 reliable facts of PT damage accumulated by the ES for 20 years of operation. Firstly, priority ranking for serviceable transformer operational activities are excluded from the sample. Then there are calculated coordinates on each of the remaining transformers. It coordinates the points, which are marked by the PT plane. The plane includes three zones: additional scheduled inspections and emergency repairs. The ES ranks PT by the distance from the origin within each zone. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen
Observation of a baryon resonance with positive strangeness in K+ collisions with Xe nuclei
The status of our investigation of low-energy Xe collisions in the Xenon
bubble chamber DIANA is reported. In the charge-exchange reaction the spectrum of effective mass shows a resonant enhancement
with MeV/c and ^24.4\sigma$. The mass and width of the
observed resonance are consistent with expectations for the lightest member of
the anti-decuplet of exotic pentaquark baryons, as predicted in the framework
of the chiral soliton model.Comment: 9 pages, 4 figure
Further evidence for formation of a narrow baryon resonance with positive strangeness in K+ collisions with Xe nuclei
We have continued our investigation of the charge-exchange reaction K^+ Xe
--> K^0 p Xe' in the bubble chamber DIANA. In agreement with our previous
results based on part of the present statistics, formation of a narrow p K^0
resonance with mass of 1537+-2 MeV/c^2 is observed in the elementary transition
K^+ n --> K^0 p on a neutron bound in the Xenon nucleus. Visible width of the
peak is consistent with being entirely due to instrumental resolution and
allows to place an upper limit on its intrinsic width: \Gamma < 9 MeV/c^2. A
more precise estimate of the resonance intrinsic width, \Gamma = 0.36+-0.11
MeV/c^2, is obtained from the ratio between the numbers of resonant and
non-resonant charge-exchange events. The signal is observed in a restricted
interval of incident K^+ momentum, that is consistent with smearing of a narrow
p K^0 resonance by Fermi motion of the target neutron. Statistical significance
of the signal is some 7.3, 5.3, and 4.3 standard deviations for the estimators
S/sqrt{B}, S/sqrt{S+B}, and S/sqrt{S+2B}, respectively. This observation
confirms and reinforces our earlier results, and offers strong evidence for
formation of a pentaquark baryon with positive strangeness in the
charge-exchange reaction K^+ n --> K^0 p on a bound neutron.Comment: 13 pages, 8 figures, some chenges in text and references, more
precise estimate of Theta(1540) to add, submitted to Phys.Atom.Nucl(Yad.Fiz.
Detecting the (Quasi-)Two-Body Decays of Leptons in Short-Baseline Neutrino Oscillation Experiments
Novel detector schemes are proposed for the short-baseline neutrino
experiments of next generation, aimed at exploring the large-
domain of \omutau oscillations in the appearance mode. These schemes emphasize
good spectrometry for charged particles and for electromagnetic showers and
efficient reconstruction of \ypi_gg decays. The basic elements are a sequence
of relatively thin emulsion targets, immersed in magnetic field and
interspersed with electronic trackers, and a fine-grained electromagnetic
calorimeter built of lead glass. These elements act as an integral whole in
reconstructing the electromagnetic showers. This conceptual scheme shows good
performance in identifying the (quasi-)two-body decays by their
characteristic kinematics and in selecting the electronic decays of the .Comment: 34 pages, 8 figure
Experimental search for radiative decays of the pentaquark baryon \Theta^+(1540)
The data on the reactions K^+Xe --> K^0 \gamma X and K^+Xe --> K^+ \gamma X,
obtained with the bubble chamber DIANA, have been analyzed for possible
radiative decays of the \Theta^+(1540) baryon: \Theta^+ --> K^0 p \gamma and
\Theta^+ --> K^+ n \gamma. No signals have been observed, and we derive the
upper limits \Gamma(\Theta^+ --> K^0 p \gamma) / \Gamma(\Theta^+ --> K^0 p) <
0.032 and \Gamma(\Theta^+ --> K^+ n \gamma) / \Gamma(\Theta^+ --> K^+ n) <
0.041 which, using our previous measurement of \Gamma(\Theta^+ --> KN) =
(0.39+-0.10) MeV, translate to \Gamma(\Theta^+ --> K^0 p \gamma) < 8 keV and
\Gamma(\Theta^+ --> K^+ n \gamma) < 11 keV at 90% confidence level. We have
also measured the cross sections of K^+ -induced reactions involving emission
of a neutral pion: \sigma(K^+n --> K^0 p \pi^0) = (68+-18) \mub and \sigma(K^+N
--> K^+ N \pi^0) = (30+-8) \mub for incident K^+ momentum of 640 MeV.Comment: 8 page
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