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This paper investigates the multi-objective optimization design of planar cable-driven parallel robots by using the evolutionary optimization algorithm. Since in cable-driven parallel robots, the cables should remain in tension in all configurations, the extent of the controllable workspace is considered as one of the design indices. This objective function is of utmost importance to the design of cable-driven parallel robots, since it considers the unidirectional properties of the cables in the analysis. In addition, in order for the robot to have suitable dexterity and accuracy and to be able to manipulate any arbitrary task in all the required directions, various kinematic indices such as global condition number, translational and rotational kinematic sensitivity indices are used. Through analysis of the conflict of these objectives within the workspace of the robot, it is shown that use of multi-objective optimization is an effective method to reach to a suitable trade-off. Furthermore, by applying multi-objective optimization methods such as the non-sorting genetic algorithm and the adaptive weighted particle swarm optimization algorithm, the optimal pareto front for the design parameters for the cable robot is obtained such that to draw a compromise between the robot designs.

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Explosion is considered as the most hazardously event in petrochemical facilities and offshore structures. In these facilities, pressure vessels are very important because their explosion may result in damage to other modules. In practical design, external blast load is applied to one side of pressure vessels as uniform load.In this paper we try to propose more realistic distribution to conform experimental results. This paper includes validation of Eulerian domain capability in finite element program ABAQUS to carryout uncoupled Eulerian Lagrangian analysis .The results show good agreement between Eulerian capability and experimental results in locations that do not have high turbulence effect, but in points where turbulence effects and vortexes are increased, error in numerical model is larger. Also, this paper shows that the method which is usually used to apply blast loads to cylindrical materials has a great error in comparison with numerical simulation and experimental results. Thus, in this paper is presented a blast load distribution which can be used in future research and industrial designs for vertical shape or horizontal shape of cylindrical materials with a variety of different diameters.

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Deriving the accurate dynamic model of robots is pivotal for robot design, control, calibration, and fault detection. To derive an accurate dynamic model of robots, all the terms affecting the robotchr('39')s dynamics are necessary to be considered, and the dynamic parameters of the robot must be identified with appropriate physical insight. In this paper, first, the kinematics of the ARAS-Diamond spherical parallel robot, which has been developed for vitreoretinal ophthalmic surgery, are investigated, then by presenting a formulation based on the principle of virtual work, a linear form of robot dynamics is derived, and the obtained results are validated in SimMechanics environment. Furthermore, other terms affecting the robot dynamics are modeled, and by using the linear regression form of the robot dynamics with the required physical bounds on the parameters, the identification process is accomplished adopting the least-squares method with appropriate physical consistency. Finally, by using the criteria of the normalized root mean squared error (NRMSE) and using different trajectories, the accuracy of the identified dynamic parameters is evaluated. The experimental validation results demonstrate a good fitness for the actuator torques (about 75 percent),  and a positive mass matrix in the entire workspace, which allows us to design the common model-based controllers such as the computer torque method, for precise control of the robot in vitreoretinal ophthalmic surgery.

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The importance of some factors, including providing temporary and permanent habitation, construction speed, increasing the material strength and decreasing the construction cost, have made the attention to choice of vertical and lateral load-bearing systems as one of the necessities of the construction industry in the event of natural disasters such as floods and earthquakes. The need for any building in any area depends on a variety of conditions that may arise at one time and disappear at another. In this study, for the first time in Iran, firstly, a rapid-fabricated steel structure with both temporary and permanent habitation ability, and the capability of moving, assembling and disassembling is introduced, and then the seismic behavior of it’s beam-to-column connection is evaluated for using in ordinary steel moment frames. In order to evaluate the three characteristics of stiffness, strength and ductility of the proposed connection, nonlinear analysis is done using ABAQUS/6.14.2 software, and the evaluation of the seismic behavior of the connection is conducted in accordance with the criterias of chapter B of ANSI/AISC 360-16. According to the results, section properties and length of the beam, end-plate thickness, location and diameter of the bolts, and the location of the stiffeners on the end-plate are the effective parameters on the stiffness and strength of the proposed connection. Among all parameters, end-plate thickness and diameter of the bolts are two important factors that mostly affect the stiffness of the connection. Investigations show that the proposed connection, by having the sufficient stiffness and strength, is able to withstand the entire plastic moment capacity of the beam. Also, the plastic hinge is occurred outside of the connection region and the final failure mode of the system is the plastic local buckling of the compression flange of the beam. The mentioned abilities make it possible to use the proposed beam-to-column connection in ordinary moment frames as a fully restrained and fully strength connection.

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