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In this article, the free vibration of a functionally graded Euler–Bernoulli beam with a tip nanoparticle and a nonlinear/linear spring constraint is presented for the first time using strain gradient theory. It is assumed that there is a nonlinear/linear spring and a nanoparticle at one end of the beam while the other is clamped. The influence of different parameters, such as the material length scale parameter, the mass of the nanoparticle, and the nonlinear/linear spring constant on the natural frequencies, is discussed in detail. The presented benchmark tables can be used as an excellent database to verify approximate or analytical solutions in future works. The presented results can be useful for those designing micro/nano electromechanical devices. [ABSTRACT FROM AUTHOR]

Friction stir processing is one of the solid-state processes which can be used to modify the structure and properties of alloys. In addition, it has become one of the most promising techniques for the preparation of the surface layer composites. To pursue cost savings and a time-efficient design, the mathematical model and optimization of the process can represent a valid choice for engineers. Friction stir processing was employed to generate an Al 6061/Al2O3-TiB2 hybrid composite layer, and mechanical properties such as the hardness and wear behavior were also measured. The relationship between the hardness and wear behavior, process parameters of friction stir processing were evaluated using an artificial neural network and response surface methodology. The rotational speed (1500–1800 rpm), traverse speeds (25, 50, 100 mm/min), and the number of passes (1–4) with constant axial force (2.61 kN) were used as the input, while the hardness and weight loss values were the output. Experimentally, the results showed that the process parameters have significant effect on hardness and wear behavior of Al 6061/Al2O3-TiB2. In addition, the developed artificial neural network and response surface methodology models can be employed as alternative methods to compute the hardness and weight loss for given process parameters. The results of both models showed that the estimated values for the hardness and wear behavior of the processed zone had an error less than 0.60%, which indicated reliability, and an evaluation of the estimated values of both models and the experimental values confirmed that the artificial neural network is a better model than response surface methodology. [ABSTRACT FROM AUTHOR]

In recent years, electricity generation by employing wind turbines has been increased significantly due to technology advancement and environmental concern. In the present study, meteorological data have been employed to compute the Weibull distribution function as well as wind power and energy density. The wind data measured at 10-min intervals at three heights of 10, 30, and 40 m above the ground. Monthly, seasonal, and annual wind speed variations are analyzed, and the performance of the selected wind turbines is evaluated. The results show that the highest wind power potential occurs in July at Lotak and in August at Shandol. The estimated annual power and energy densities demonstrated that both investigated sites are suitable for large-scale power generation. Finally, the levelized cost of energy (LCOE) is employed to evaluate the economic feasibility of electricity generation from wind power energy. It was demonstrated that the minimum cost of energy achieved by Dongfang DF100-2500 model with LCOE of 0.0830 and 0.0786 USD/kWh in Lotak and Shandol, respectively. [ABSTRACT FROM AUTHOR]

According to the present literature review, the axial vibration of the axially functionally graded (FG) tapered nanorod with attached nonlinear spring has not been addressed so far. In this study, the axial vibration of the FG tapered nanorod is studied based on Eringen's nonlocal theory, in which one end of the nanorod is clamped and the other end is attached to a nonlinear spring and a nanoparticle. The influence of different parameters such as the nonlinear spring constant, mass of the nanoparticle, and the nonlocal parameter on the natural frequencies is presented in detail. The solutions via Tables can be utilized as a reliable reference for evaluating the validity of future researches. The presented nonlocal solutions can be helpful for those who are interested in designing micro/nano electromechanical systems. [ABSTRACT FROM AUTHOR]