The Department of Control and Systems Engineering Holds a Seminar for a Doctoral Dissertation

Dr. Zeina Khalil Abdul Amir, a lecturer in the Department of Control and Systems Engineering, gave a lecture entitled (The Effect of Fear, Antipredator, Refuge, Age Stages and Disease on the Dynamics of Some Ecosystems) related to her dissertation for which she received a doctorate from the University of Baghdad / Faculty of Science. Three mathematical models were proposed for the study. The first model consists of a food chain representing a prey and predator model and the effect of anti-predation behavior which appears due to the prey fear of the predator with a predation function of (Holling-type-II) between the prey and the first predator and the function (Lotka-Volterra) between the first predator and the second predator. A refuge for prey and a harvest for the first predator were also proposed. In the second model, an epidemiological ecosystem with age stages, harvesting and shelter for prey only was proposed. The disease is of the type (SIS) that spreads only among young prey through contact infection and from an external source. Transmission of infectious disease between prey was prescribed in writing and the predation function was of the type (Lotka-Volterra). The third model includes two preys and one predator with age stages which divided the predator into young predators and a mature predator since the young predators are unable to reproduce and hunt. The mature predator preys on the first prey with a predation function of the type (Holling-II) and preys on the second prey with a predation of the type (Holling-IV). Anti-predation behavior and collective defense factors were formulated. Numerical simulation was used to study the overall DNAM of all the models proposed above with two sets of parameter values and two sets of different elementary points for each of the three systems not only to confirm the theoretical results obtained, but also to show the variance effects of each parameter on the proposed model. Results:

• The first model: death, harvest and fear affect the stability of this ecosystem.

• The second model: the rate of growth, harvest, death and the amount of transformation of food have a direct impact on the stability of this ecosystem.

• The third model: Growth rate, predation rate, satiety and death rate have an important impact on the stability of this system. The seminar was attended by the Assistant Head of the Department for Scientific Affairs and Graduate Studies Prof. Dr. Mohamed Yousef Hassan.