Comparative study of evolution of structured flows at boundary of the regime change “diffusion — concentration convection” in isothermal multicomponent mixing in gases by techniques of visual and numerical analysis

During isothermal multicomponent diffusion process, the number of effects appear that are not observed visually when mixed in binary mixtures. These include occurrence of convective instability with subsequent formation of structured flows. The feature of this type of mixing is that convection is realized under conditions of decrease in density of mixture with height. Flow visualization method allows to fix information about distribution of medium parameters by dynamics of structures in convective flows. Application of computer processing methods, as well as techniques of identifying images of thermophysical fields, allows to obtain quantitative information about convective flows. For an isothermal ternary gas mixture heliumargonnitrogen, shadow images of structural formations formed in convective flows due to the instability of mechanical equilibrium are represented in this work. To carry out digital analysis of experimental shadow images, a simplified virtual model of the lower chamber of the diffusion cell was created. Based on digital analysis of visual images, quantitative characteristics related to estimation of the size of convective formations, period of their formation, and linear velocity of convection cells when moving through diffusion channel are presented. It has been established that the growing convective disturbances arising in the system cause a change in the characteristic scale of convective cells. The analysis of shadow images also showed that a vortex is formed in convective flows, which consists mainly of a component with the highest molecular weight. Comparison of visual images of experimental fields with simulation flows is implemented, on the basis of which composition of mixture components in convective structures is estimated. It is shown that the obtained value of the concentration of the heavy component in the vortex filament can be taken as the minimum

TSUNAMI DANGER IN THE KERCH STRAIT

The numerical simulation of the tsunami wave propagation along the Kerch Strait is carried out with localization of possible sources at the entrances to the strait, both from the Black Sea and from the Sea of Azov. Under computation of both generation and tsunami propagation, a system of nonlinear shallow water equations was used. The potential strong earthquakes (with earthquake magnitude M ~ 7) with seismic sources of elliptical shape were considered. Detailed assessments of the wave characteristics in the Kerch Strait, in particular for the Crimean bridge area, were carried out. The obtained wave characteristics are compared with the available data of the work of other authors

An Extreme Solar Event of 20 January 2005: Properties of the Flare and the Origin of Energetic Particles

The extreme solar and SEP event of 20 January 2005 is analyzed from two perspectives. Firstly, we study features of the main phase of the flare, when the strongest emissions from microwaves up to 200 MeV gamma-rays were observed. Secondly, we relate our results to a long-standing controversy on the origin of SEPs arriving at Earth, i.e., acceleration in flares, or shocks ahead of CMEs. All emissions from microwaves up to 2.22 MeV line gamma-rays during the main flare phase originated within a compact structure located just above sunspot umbrae. A huge radio burst with a frequency maximum at 30 GHz was observed, indicating the presence of a large number of energetic electrons in strong magnetic fields. Thus, protons and electrons responsible for flare emissions during its main phase were accelerated within the magnetic field of the active region. The leading, impulsive parts of the GLE, and highest-energy gamma-rays identified with pi^0-decay emission, are similar and correspond in time. The origin of the pi^0-decay gamma-rays is argued to be the same as that of lower energy emissions. We estimate the sky-plane speed of the CME to be 2000-2600 km/s, i.e., high, but of the same order as preceding non-GLE-related CMEs from the same active region. Hence, the flare itself rather than the CME appears to determine the extreme nature of this event. We conclude that the acceleration, at least, to sub-relativistic energies, of electrons and protons, responsible for both the flare emissions and the leading spike of SEP/GLE by 07 UT, are likely to have occurred simultaneously within the flare region. We do not rule out a probable contribution from particles accelerated in the CME-driven shock for the leading GLE spike, which seemed to dominate later on.Comment: 34 pages, 14 Postscript figures. Solar Physics, accepted. A typo corrected. The original publication is available at http://www.springerlink.co

Novel Bound States Treatment of the Two Dimensional Schrodinger Equation with Pseudocentral Plus Multiparameter Noncentral Potential

By converting the rectangular basis potential V(x,y) into the form as V(r)+V(r, phi) described by the pseudo central plus noncentral potential, particular solutions of the two dimensional Schrodinger equation in plane-polar coordinates have been carried out through the analytic approaching technique of the Nikiforov and Uvarov (NUT). Both the exact bound state energy spectra and the corresponding bound state wavefunctions of the complete system are determined explicitly and in closed forms. Our presented results are identical to those of the previous works and they may also be useful for investigation and analysis of structural characteristics in a variety of quantum systemsComment: Published, 16 page

Search for the doubly heavy baryon Ξbc+\it{\Xi}_{bc}^{+} decaying to J/ψΞc+J/\it{\psi} \it{\Xi}_{c}^{+}

A first search for the $\it{\Xi}_{bc}^{+}\to J/\it{\psi}\it{\Xi}_{c}^{+}$ decay is performed by the LHCb experiment with a data sample of proton-proton collisions, corresponding to an integrated luminosity of $9\,\mathrm{fb}^{-1}$ recorded at centre-of-mass energies of 7, 8, and $13\mathrm{\,Te\kern -0.1em V}$. Two peaking structures are seen with a local (global) significance of $4.3\,(2.8)$ and $4.1\,(2.4)$ standard deviations at masses of $6571\,\mathrm{Me\kern -0.1em V\!/}c^2$ and $6694\,\mathrm{Me\kern -0.1em V\!/}c^2$, respectively. Upper limits are set on the $\it{\Xi}_{bc}^{+}$ baryon production cross-section times the branching fraction relative to that of the $B_{c}^{+}\to J/\it{\psi} D_{s}^{+}$ decay at centre-of-mass energies of 8 and $13\mathrm{\,Te\kern -0.1em V}$, in the $\it{\Xi}_{bc}^{+}$ and in the $B_{c}^{+}$ rapidity and transverse-momentum ranges from 2.0 to 4.5 and 0 to $20\,\mathrm{Ge\kern -0.1em V\!/}c$, respectively. Upper limits are presented as a function of the $\it{\Xi}_{bc}^{+}$ mass and lifetime.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-005.html (LHCb public pages