Ozhan Kayacan

The effects of the nonextensivity on the dimerization process and nematic ordering

The influence of the dimerization process on the nematic ordering is investigated by using a nonextensive thermostatistics, namely Tsallis thermostatistics (TT). A theoretical model taking into account the dimerization influence on the nematic scalar order parameter has been recently presented (Phys. Lett. A 256 (1999) 309). Our study considers this model and the theoretical predictions for the nematic order parameter are improved by using TT.

The influence of nonextensivity on orientational ordering in liquid crystal systems with variable molecular shape

A generalized model taking into account the photoisomerization influence on the nematic ordering is presented. This generalized theory is used to investigate the effect of the nonextensivity on the concentration dependence of the long-range order parameter. The q-dependent variation of the concentration of cis-trans isomers and of the order parameter with the time of exposure to the illumination is investigated within nonextensivity. It is also shown that for sufficiently long exposition of the mesophase to the illumination the nematic phase cannot disappear for some value of the entropic index, coming from Tsallis statistics. Moreover it is shown that long range interactions or the fractal structure in the liquid crystalline system might affect the characteristics of the phase transition in the physical system. We think therefore that this conclusion might shed light on the interaction potential energy terms in the similar system in future possible experiments, even to be performed on new objects with different symmetries.

Nonextensive thermostatistical approach to the thermoluminescence decay

In this study, thermoluminescence decay is investigated within Tsallis thermostatistics (TT). We believe that this is the first attempt to handle the thermoluminescence decay process within TT. The generalized form of glow intensity vs temperature is examined and the effect of the nonextensitivity is shown for various values of the entropic index q. The results are interpreted in terms of the entropic index q and the occupied trap density n.

Study on bi-directional pedestrian movement using ant algorithms

A cellular automata model is proposed to simulate bi-directional pedestrian flow. Pedestrian movement is investigated by using ant algorithms. Ants communicate with each other by dropping a chemical, called a pheromone, on the substrate while crawling forward. Similarly, it is considered that oppositely moving pedestrians drop ‘visual pheromones’ on their way and the visual pheromones might cause attractive or repulsive interactions. This pheromenon is introduced into modelling the pedestrians’ walking preference. In this way, the decision-making process of pedestrians will be based on ‘the instinct of following’. At some densities, the relationships of velocity–density and flux–density are analyzed for different evaporation rates of visual pheromones. Lane formation and phase transition are observed for certain evaporation rates of visual pheromones.