Sharif Digital Repository

In this paper, the thermo-dynamic analysis of contact-impact problem is presented in the large deformation of hyperelastic material based on the Taylor-Galerkin method. The technique is applied for the time domain discretization of thermo-dynamic governing equations in the advection-diffusion problems. The impenetrability condition and frictional contact constraints are fulfilled by imposing the augmented-Lagrange technique for nonmatching contact surfaces. The Taylor-Galerkin method is employed to describe the advection-diffusion effect in the numerical solution of parabolic equation of unsteady heat transfer condition. The effect of temperature is taken into account in the stress field by... 

In this paper, a novel multi-step method is proposed for solving the inverse point kinetics problem using Lagrange polynomial method. By use of this approach, the need for nuclear power history or the Laplace transform is vanished. Furthermore, the accuracy of the method is of order hn for the (n + 1)-point formula, where h is the computational time-step. The three- and five-point formulas of the Lagrange method are used for on-line reactivity calculations and results are benchmarked against reference solutions for different nuclear power forms. Moreover, results for different computational time-steps are compared in each case. The results show the accuracy of the proposed method in all... 

In this paper, the rotation of a two-stage turbine rotor is studied. The goal of this article is to present a practical understanding of terminology and behavior based in visualizing how a shaft vibrates, and examining issues that affect vibration. Analytical solutions to predict critical speeds are developed with the aid of the Lagrange method and the Modal analysis. Results are given in tables and diagrams. The matrix solution showed that the critical speeds change as the rotating speed of the shaft increases. It was inferred from the results that even new critical speeds could be generated. Due to the gyroscopic effects, the rotor undergoes some precession which is indicated by the... 

In this article, dynamic equations of a single wheel robot, known as Gyrover, through Lagrange method applying a new approach will be addressed. There is no simplification on the dynamic analysis. Considering any possible differentiable function for the road's curve, the effect of the road's roughness is completely described in the dynamic equation evaluation. Although there are complicated relations between the wheel and rough terrain, due to the efficient generalized coordinate selection, closed form dynamic equation of the motion is derived. Because of the closed form formulation, required time for simulation will be reduced. From the proposed complete model a simplified model for the... 

In this paper, dynamic modeling and control problem for transfer of a sloshing liquid container suspended through rigid massless links from a team of quadrotors are investigated. By the proposed solution, pose of the slung container and fluid sloshing modes are stabilized appropriately. Dynamics of the container-liquid-quadrotors system is modeled by Euler-Lagrange method. Fluid slosh dynamics is included using multi-mass-spring model. According to derived model, a proper control law is designed for a system with three or more quadrotors. Implementing the proposed control law, quadrotors can control pose of the container, directions of the links and liquid sloshing modes simultaneously.... 

With the exception of a few works, the current approaches to aerial manipulation control do not typically consider the system constraints in the control design process. Also, the issue of closed-loop stability in the presence of system constraints is not thoroughly analyzed. In this paper, a novel multi-stage model predictive control (MPC)-based approach for aerial manipulation is proposed to ensure the closed-loop stability in the presence of model uncertainties and external disturbances, while satisfying the operational constraints. The detailed nonlinear model of a general aerial manipulator, consisting of a quadrotor equipped with a 3 degrees of freedom manipulator, is first developed...