This paper presents the effect of preload on nonlinear dynamic behavior of a rigid rotor supported by two-lobe aerodynamic noncircular journal bearing. A finite element method is employed to solve the Reynolds equation in static and dynamical states and the dynamical equations are solved using Runge-Kutta method. To analyze the behavior of the rotor center in the horizontal and vertical directi...

many real time processes have complex, uncertain and nonlinear dynamics. boilers are nonlinear, time varying, multi-input multi-output (mimo) systems, whose states generally vary with operating conditions. the major problem in controlling that system is that its drum water pressure and steam flow dynamics include an integrator that results a critically stable behavior. conventional controller p...

presence of risks and uncertainties inherent in project development and implementation playssignificant role in poor project performance. thus, there is a considerable need to have an effective riskanalysis approach in order to assess the impact of different risks on the project objectives. a powerful riskanalysis approach may consider dynamic nature of risks throughout the life cycle of the pr...

Because of electricity subsidies, electricity price in Iran is much lower than its real value, and the growth of electricity demand is much more than its rational rate, which in turn implies ever increasing investment in the electricity section by the Government. Therefore, the recent Government policies are based on elimination of electricity subsidies, followed by commissioning complete elect...

fuzzy cognitive maps (fcms) have successfully been applied in numerous domains to show the relations between essential components in complex systems. in this paper, a novel learning method is proposed to construct fcms based on historical data and by using meta-heuristic: genetic algorithm (ga), simulated annealing (sa), and tabu search (ts). implementation of the proposed method has demonstrat...

in this study, eutrophication was investigated in lake ontario to identify the interactions among effective drivers. the complexity of such phenomenon was modeled using a system dynamics approach based on a consideration of constant and variable stoichiometric ratios. the system dynamics approach is a powerful tool for developing object-oriented models to simulate complex phenomena that involve...

this research presents a dynamic mathematical system for modeling and simulating the quality management process in construction projects. through sets of cause and effect feedback loops, all factors that internally and externally affect the quality management process are addressed. the proposed system integrates fuzzy logic with system dynamics simulation scheme to consider the uncertainties as...

job satisfaction (js) plays important role as a competitive advantage in organizations especially in helth industry. recruitment and retention of human resources are persistent problems associated with this field. most of the researchs have focused on the job satisfaction factors and few of researches have noticed about its effects on productivity. however, little researchs have focused on the ...