The results of a constructively simple high-tech small-sized integrated element of the Ka-band electric beam scanning reflective phased array antenna (PAA) development are shown. Beam scanning sector ...of the phased array antenna is up to 60 by both coordinates. The PAA element is based on the Faraday type waveguide ferrite phase shifter, which works on the circular polarized electromagnetic waves. More than 30000 PAA elements has been produced, 100% control and statistical data processing of their main characteristics has been carried out. Graph for initial phases and steepness of linearized phase characteristics, medium and maximum losses of PAA elements are performed. Average value of the average deviation for parameters which is important for PAA and the beam control system design have been determined. The developed element can be used in PAA which have different sizes, forms and sectors of electrical beam scanning. Small deviations in the characteristics of PAA elements from the linearized characteristics indicate the high quality of the production and their identity, which makes it possible to create PAA without taking into account the real individual parameters of mass-produced PAA elements.
A previously developed self-consistent field method is used to study an arbitrary finite set of identical spherical particles of arbitrary density moving in a uniform inviscid incompressible flow ...specified at infinity in the presence of a flat wall. For a given initial particle distribution in space, expressions for the particle and fluid velocities are derived taking into account the collective hydrodynamic interaction of the particles with each other and the wall. For a statistically uniform particle distribution in a semibounded inviscid fluid, analytical averaged particle and fluid velocity profiles are obtained in the first approximation with respect to the particle volume fraction in the suspension.
The problem of the flow of an ideal incompressible fluid is considered along a flat surface, perpendicular to which a stationary granular layer is located. The granular-layer model is adopted as the ...ensemble of an infinite number of identical spherical granules, which are statistically uniformly distributed in a layer of finite thickness. The problem is solved on the basis of the previously developed self-consistent field method. In the first approximation in the volume fraction of granules in the layer, the functions describing the ensemble-averaged fluid-velocity profile are obtained in analytical form both inside and outside the layer.
The restoration of chiral symmetry and its subsequent breaking through a phase transition has been predicted to create regions of Disoriented Chiral Condensates (DCC). This phenomenon has been ...predicted to cause anomalous fluctuations in the relative production of charged and neutral pions in high-energy hadronic and nuclear collisions. The WA98 experiment has been used to measure charged and photon multiplicities in the central region of 158 AGeV Pb+Pb collisions at the CERN SPS. In a sample of 212646 events, no clear DCC signal can be distinguished. Using a simple DCC model, we have set a 90% C.L. upper limit on the maximum DCC production allowed by the data.
A measurement of direct photon production in {sup 208}Pb+ {sup 208}Pb collisions at 158A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central ...collisions is extracted as a function of transverse momentum in the interval 0.5<p{sub T}<4 GeV/c . A significant direct photon signal, compared to statistical and systematical errors, is seen at p{sub T}>1.5 GeV/c . The result constitutes the first observation of direct photons in ultrarelativistic heavy-ion collisions. It could be significant for diagnosis of quark-gluon-plasma formation.
Charged particles and photons have been measured in central Pb + Pb collisions at 158 A GeV in a common (eta-phi)-phase space region in the WA98 experiment at the CERN SPS. The measured distributions ...have been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged-neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the A Delta eta-Delta phi region. (C) 2011 Elsevier B.V. All rights reserved.
Charged particles and photons have been measured in central Pb+Pb collisions at 158 A GeV in a common (η–ϕ)-phase space region in the WA98 experiment at the CERN SPS. The measured distributions have ...been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged–neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the Δη–Δϕ region.
On the virtual mass of a rough sphere Gus’kov, O.B.
Journal of applied mathematics and mechanics,
2017, 2017-00-00, 20170101, Letnik:
81, Številka:
4
Journal Article
Recenzirano
Within the framework of the model of granular roughness formed by a large number of small grains distributed over the surface of a sphere, the accelerated combined motion of the sphere and the ...spherical grains attached to its surface in a resting ideal fluid is considered. Using the self-consistent field method, an expression is obtained for the virtual mass of the rough sphere as a function of the size of the grains and their distribution over the sphere surface. For a statistically uniform distribution of the grains over the sphere surface, the dependence of the mean value of the virtual mass of the rough sphere on the grain size is determined in the first approximation in their volume fraction.
The problem of the motion of a spherical bubble of arbitrary size with a specified velocity in a dilute suspension of solid spherical particles is considered in the Stokes approximation for a ...carrying continuous medium. An expression is obtained for the drag of the bubble in the first approximation in the volume concentration of the dispersed phase. Using the results obtained an expression is derived for the effective viscosity of the suspension, “as seen” by the spherical bubble as it moves through the dispersed medium. It is shown that the coefficient for the volume concentration in the formula for the effective viscosity of the suspension depends on the ratio of the dimensions of the dispersed particles and of the bubble. In the limit, when this ratio approaches zero, the coefficient obtained is identical with Einstein's result for the effective viscosity of the suspension. However, this coefficient may differ considerably from Einstein's result for “non-point” dispersed particles. By comparing this result with the similar result obtained earlier for the case of the motion of a rigid sphere in a viscous suspension it is shown that the coefficient for the volume concentration in the formula for the effective viscosity of the suspension depends not only on the size of the body, but also on the form of the boundary conditions on its surface.
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