Sharif Digital Repository

This paper presents a method to maximize the output power of a DFIG wind turbine. In this method, an optimization technique based on mathematical analysis has been used. The modeling of DFIG is performed using MATLAB. To evaluate the maximum output power of a DFIG, detailed expressions for output power and losses are derived as functions of generator slip, the magnitude and phase angle of rotor excitation voltage in various wind velocities. The outcomes of this method demonstrate that maximum output power of a DFIG wind turbine do not happen in the maximum input power (the mechanical power of wind turbine)  

In this paper, we propose a new 4-legged 6-DOF redundantly actuated UPS parallel mechanism. Kinematics, singularity and dynamics analyses of the proposed mechanism are addressed. Inverse kinematics has a closed-form solution, whereas the forward kinematics has a semi-closed form solution. Also, the Jacobian matrix has been determined using the concept of reciprocal screws. Using the principle of virtual work and minimum norm method, a general formulation for the inverse dynamics of redundantly actuated parallel manipulator is presented. Moreover, the proposed redundant mechanism has been compared with a similar but nonredundant mechanism in three aspects: reachable points, and actuation... 

This paper focuses on the biomechanical aspects of the human lower extremity loading condition during backpack load carrying. A biomechanical framework was generated with the aim of employing a block-oriented structure of Simulink integrated with the Virtual Reality Toolbox of MATLAB software to provide a simulation study of the musculoskeletal system in a virtual environment. In this case, a ten-degrees-of-freedom musculoskeletal model actuated with sixteen muscles in each leg was utilized to simulate movement in the sagittal plane. An inverse dynamics based optimization approach was employed to estimate the excitation level of the muscles. In addition, distributions of the mechanical power... 

In this study, the authors propose a processor allocation mechanism for run-time assignment of a set of communicating tasks of input applications onto the processing nodes of a chip multiprocessor, when the arrival order and execution lifetime of the input applications are not known a priori. This mechanism targets the on-chip communication and aims to reduce the power and latency of the network-on-chip employed as the communication infrastructure. In this work, the authors benefit from the advantages of non-contiguous processor allocation mechanisms, by allowing the tasks of the input application mapped onto disjoint regions (submeshes) and then virtually connecting them by bypassing the... 

The objective of this study was to quantify individual muscle function differences between level walking and backpack load carriage at the same speed by using a muscle-actuated forward dynamics simulation. As experimental investigations have revealed that backpack loads of up to 64 per cent of an individual's body mass have little effect on the sagittal plane gait kinema-tics, further biomechanical analyses are necessary to investigate the contributions of individual muscle coordination strategies to achieve a given motor task by mechanical power generation, absorption, and transference to each body segment. A biomechanical framework consisting of a musculoskeletal model actuated by 18... 

The main scope of this study is to analyse muscle-driven forward dynamics simulation of stair locomotion to understand the functional differences of individual muscles during the movement. A static optimization was employed to minimize a performance criterion based on the muscle energy consumption to resolve muscle redundancy during forward dynamics simulation. The proposed method was employed to simulate a musculoskeletal system with ten degrees of freedom in the sagittal plane and containing 18 Hill-type musculotendon actuators per leg. Simulation results illustrated that simulated joint kinematics closely tracked experimental quantities with root-mean-squared errors less than 1°. In...