Pseudo-anapole regime in terahertz metasurfaces

We present the numerical, theoretical, and experimental study of a terahertz metasurface supporting a pseudo-anapole. Pseudo-anapole effect arises when electric and toroidal dipole moments both tend to a minimum, instead of destructive interference between electric and toroidal dipole moments in conventional anapole mode. Such overlap allows resonance suppression of electric type radiation. Thus it becomes possible to study the multipoles of other families and higher order excitations. We estimate multipole contribution to the metasurface response via the multipole expansion method. The series is extended with such terms as mean-square radii and multipole interference. We also study the metasurface geometrical tunability. Via scaling, we demonstrate that it is possible to control the metasurface toroidal and electric responses independently. This in turn proves the fact that these multipoles have different physical origin. Moreover, we demonstrate that the proposed metasurface allows excitation of coherent magnetic dipole and electric quadrupole modes, which is crucial for planar cavities and lasing spasers in nanophotonics

Estimation of the probability density parameters of the interval duration between events in correlated semi-synchronous event flow of the second order by the method of moments

We consider a correlated semi-synchronous event flow of the second order with two states; it is one of the mathematical models for an incoming stream of claims (events) in modern digital integral servicing networks, telecommunication systems and satellite communication networks. We solve the problem of estimating the probability density parameters of the values of the interval duration between the moments of the events occurrence by the method of moments for general and special cases of setting the flow parameters. The results of statistical experiments performed on a flow simulation model are given

Distribution Parameters Estimation in Recurrent Synchronous Generalized Doubly Stochastic Flow of the Second Order

We solve the estimation problem of the probability density parameters of the inter-event interval duration in a synchronous generalized flow of the second order, which can be used as a powerful mathematical model for the arrival processes in queuing systems and networks. The explicit form of the parameter estimates is determined by the method of moments on the basis of observations of the doubly stochastic flow under the recurrence conditions that are formulated in terms of the joint probability density of the durations of two adjacent inter-event intervals. The quality of the estimates is established by using the model, reproducing the flow behavior under conditions of complete observability