An advanced system for determination of face mask efficiency is developed and presented in this paper It is based on a high-end scanning mobility particle sizer (SMPS), which was able to detect nanoparticles from the diameter of 10 nm up to 1000 nm in 129 equidistant channels Two fitting installations for face masks were used: a mannequin doll head, to simulate realistic use of face mask and a tight-fit system which prevents the air leak The SMPS-based system was able to determine mask efficiency for different particle sizes © 2020 Danube Adria Association for Automation and Manufacturing, DAAAM All rights reserved

In this paper we will observe the model of competitive types and it will be analyzed using the nullcline method. It will be shown that this model has four points of equilibria, which are stable or unstable depending on the parameters a and b. The local stability of these points was investigated and global dynamics was determined using nullcline methods, that is, the bases of attraction of these points were shown.

Here we examine the behavior of a rational Lotka - Volterra model which is a modification of the ordinary polynomial case. We find nonnegative equilibrium points and define conditions in the parametric space for the stable positive equilibrium point. We also prove existence of the stable limit cycle in the case of the unstable positive equilibrium point.

In this paper will be observed the population dynamics of a three-species Lotka-Volterra model: two predators and their prey. This simplified model yields a more complicated dynamical system than classic Lotka-Volterra model. We will give the conditions under which one of the predators becomes extinct and when the coexistence between predators is possible. Given will be sufficient conditions for the existence of solutions for certain classes of Cauchy’s solutions of Lotka-Volterra model. The behavior of integral curves in the neighborhoods of an arbitrary integral curves will be considered.

We investigate the local stability and the global asymptotic stability of the difference equation , with nonnegative parameters and initial conditions such that , for all . We obtain the local stability of the equilibrium for all values of parameters and give some global asymptotic stability results for some values of the parameters. We also obtain global dynamics in the special case, where , in which case we show that such equation exhibits a global period doubling bifurcation.