This work addresses the Kidney Transplant Problem (KTP) with priority in the care of organ receptor patients and proposes a resolution methodology based on operational research techniques. In this case, the main objective is to perform as many transplants as possible with the lowest surgical and mobility costs, considering the geographical positions of donors, recipients and hospitals, as well as surgical costs accredited hospitals to perform kidney transplant surgeries. The problem meets the characteristics imposed by the Unified Health System (SUS) of the Health Ministry from the Federative Republic of Brazil. Thus, our work aims to reduce the waiting time of the queue of these patients who need a kidney transplant and give an optimized planning to perform this task. A literature review was made for the specific problem and we found the Kidney Exchange Problem (KEP) with different characteristics from the KTP. It developed for the specific problem: a mathematical model; a set of instances; and a metaheuristic, based on Genetic Algorithm (AG), applies it to solving the problem. The results of the AGare presented with great degree of satisfaction.

Keywords: Genetic Algorithm, Kidney Transplant, Metaheuristic, Combinatorial Optimization.

for several years structural ring footings have been used for their durability advantages beneath the shallow foundations of maritime structures. However, limited knowledge of the efficiency and use of ring footings as traditional shallow foundations is available. The ability of these foundations was tested in of laboratory testing in this study. The effects of skirt rigidity and depth were analyzed in this sense on the bearing ability of skirted footing models. The test results were then compared with other equations of bearing power. It was determined that using structural ring, both soil-rings and the soil-footing depth would increase their support capability up to 1.62 times....

Keywords: ...

Air pollution in cities and urban sectors are increasing significantly on a time scale at global level. This alarming fact is substantiated with its gravity in the sense that more than 80% of people living in urban areas are exposed to air quality levels that exceed the World Health Organization (WHO) limits. The situation world over is more critical to populations in low-income cities which are most impacted. According to the urban air quality database, 98% of cities in low- and middle income countries with more than 100 000 inhabitants do not meet WHO air quality guidelines. However, the cities in high-income countries this percentage decreases to 56%. The WHO reveals the fact that around 3000 cities in 103 countries have started measuring air pollution levels and recognizing the associated health impacts. With declines of urban air quality , the risk of stroke, heart disease, lung cancer, chronic and acute respiratory diseases, including asthma, increases for the people who live in these cities.....

Keywords: Air pollution, urban areas, indoor and outdoor air pollution, health impacts, air pollution episodes

This paper analyzes the dynamic behaviors including stability and Hopf bifurcations of a class of three dimensional nonlinear chaotic systems with analytical and numerical methods. All the equilibriums and stability of the system are studied in detail for different values of system parameters. It is presented that there may exist three equilibriums for this system. The stability conditions of these equilibriums are obtained with the Routh–Hurwitz criterion. Using the Hopf bifurcation theorem and the first Lyapunov coefficient, the system condition and type of Hopf bifurcation for this system is obtained analytically. It is demonstrated that there may exist subcritical Hopf bifurcations under certain system parameters for this system. Using the Runge-Kutta method, numerical simulations including phase portraits and time history curves are also given, which verify the analytical results.

Keywords: Chaotic system , Stability, Hopf Bifurcation