Many of the proposed methods introduce the perforated fin with the straight direction to improve the thermal performance of the heat sink. The innovative form of the perforated fin (with inclination angles) was considered. Present rectangular pin fins consist of elliptical perforations with two models and two cases. The signum function is used for modeling the opposite and the mutable approach of the heat transfer area. To find the general solution, the degenerate hypergeometric equation was used as a new derivative method and then solved by Kummer's series. Two validation methods (previous work and Ansys 16.0-Steady State Thermal) are considered. The strong agreement of the validation results (0.31% to 0.52%) lends to the reliability of the presented model. It was found that use of the perforated fin leads to decreased thermal resistance and improvement in the thermal performance of the pin fin by enhancing the heat transfer and increasing Nusselt number. Also, the increase of the inclination angle, size, and number of perforations can be used to optimize the present model by maximizing the heat transfer area and minimizing both the weight and length of the pin fins. wileyonlinelibrary.com/journal/htj
Perforated fins, because of their compactness, low weight and high effectiveness are widely used in heat sinks to enhance the heat transfer from electronic equipments. The innovative form of the perforated fin (with inclination angles) was considered for the rectangular pin fin. In the analytical solution, the Degenerate Hypergeometric Equation (DHE) was used as a new derivative method and then solved by Kummer's series. Also, Signum function is used to model the opposite and mutable approach heat transfer area. This article presents a combined open literature and Experimental work of various cases to validate the analytical study. Two models were perforated experimentally at the 5mm from bottom tip at a various inclination angles by using a wire cut electrical discharge machining (Wire EDM) and EDM drilling machine. The present mathematical model has good reliability according to the high agreement of the validation results about (0.33%-1.4%). It was found that use of the inclined perforation fin leads to decreased thermal resistance and improvement in the thermal performance of the pin fin by enhancing the heat transfer. Also, the optimization can be achieved by minimizing the weight and length of the pin fin based on the Multi advantages of the present model. Likewise, Entropy generation was minimized with increases the open area ratio at a certain Rayleigh number and constant heat flux.
This paper presents a robust control method for the trajectory control of the robotic manipulator. The standard Computed Torque Control (CTC) is an important method in the robotic control systems but its not robust to system uncertainty and external disturbance. The proposed method overcome the system uncertainty and external disturbance problems. In this paper, a robustification term has been added to the standard CTC. The stability of the proposed control method is approved by the Lyapunov stability theorem. The performance of the presented controller is tested by MATLAB-Simulink environment and is compared with different control methods to illustrate its robustness and performance.
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