Study on Critical Density of Percolation in Crowds in Public Areas

The percolation model is an effective tool to solve the problem of fluid flow in the pores; the situation of outsiders crossing the crowd is similar. This paper verifies the obvious percolation phenomenon in the randomly distributed crowd by [Formula: see text] simulation and reveals several characteristics and laws of the crowd percolation phenomena. Studies have shown that sites with different spatial dimensions have different densities of crowd percolation: when the actual density of the crowd is greater than the critical density of the crowd percolation, the outsider is difficult to pass through the crowd; otherwise, the outsider can pass through the crowd easily. Therefore, the critical density of crowd percolation can be one of the indicators of crowd management in public areas, which will provide important guidance for the design of public areas, site selection of public activities and crowd management.

Magnetic properties of poly(p-xylylene)-Ni nanocomposites

The dependence of electrical and magnetic properties on structure of thin poly(p-xylylene) - nickel nanocomposite films with Ni concentrations from 5 to 30 vol.% was studied. It was found that metal concentration strongly affects size and oxidation state of the nanoparticles. Effect of the filler content on electrical and magnetic properties of the nanocomposites was revealed. These properties are determined by percolation phenomenon, with the percolation threshold value of about 10 vol.%. The well pronounced magnetic hysteresis as well as ferromagnetic ordering were observed at Ni content above the percolation threshold. The diagrams of magnetic properties of these composites as a function of composition and temperature were elaborated.

Magnetic percolation in CN-bridged ferrimagnetic coordination polymers

The magnetic percolation phenomenon in the magnetic structure of MnII–NbIV/MoIV coordination polymers was studied by a selective diamagnetic substitution of NbIV by MoIV ions.