Abstract Nowadays, despite the implementation of new wind farms in Brazil, it still is difficult to form partnerships with companies in the sector, which significantly contributes to the gap in information provided by national literature and the lack of knowledge about the mechanical behavior of wind turbines subjected to transient wind effects. Therefore, through a Research and Development Project to optimize and improve modeling in wind systems, the Brazilian electric power company Eletrobras Furnas aims to facilitate the construction of smaller wind turbines to supply energy to regions far from the Brazilian coast that do not have high generation potential due to the incidence of low-speed winds. Two relevant aspects directly linked to the performance of this kind of structures are: (i) determining their natural frequency and (ii) ensuring that this frequency does not coincide with any external vibration frequency that the structure may experience in its lifetime. Wind turbines are complex systems with many degrees of freedom and their own frequencies associated with the respective mode shapes in which they naturally vibrate. These frequencies are inversely related to the mass and directly related to the stiffness of the structure. Thus, through numerical modeling using the Finite Element Method, the present article aims to list some of the main factors that can affect the prediction of the natural frequency of a real-scale wind turbine prototype and to evaluate its dynamic behavior, considering its rotor revolution frequency, its blade passing frequency and the wind characteristics of its operating area. Nowadays Brazil sector effects Therefore lowspeed low speed winds i (i ii (ii lifetime vibrate Thus Method realscale real scale area

Abstract The shearing behavior of discontinuities is one of the factors with major influence on rock slope stability analysis, which is predictable when adopting different analytical models. However, these methodologies, generally of a purely deterministic nature, do not allow an assessment of the influence of the variability of the input parameters of the models on the shear behavior of unfilled rock discontinuities and, consequently, on the risk involved in the rock slope stability analyses. The purpose of this article is to present a methodology for rock slope risk assessment based on the development of a model to predict the shear behavior of unfilled rock discontinuity considering the variability of its input parameters, using a Mamdani fuzzy controller. The input variables of the model are the boundary normal stiffness and initial normal stress acting on the discontinuity, its roughness, the uniaxial compressive strength, the basic angle of friction of the intact rock and the shear displacement imposed on the discontinuity. The model outputs are the membership functions for the shear strength and dilation of the unfilled rock discontinuity, and from which the membership function can be defined for the factor of safety of the rock slope considering the failure mechanism governed by discontinuity. The results reveal the use and importance of fuzzy logic and fuzzy number operations in assessing the risk in rock slopes and may be used even in situations where there are major uncertainties on the existing information of the characteristics of the unfilled discontinuities. analysis However methodologies nature consequently analyses controller roughness

Abstract It is well known that learning about the mechanical behavior of a fractured rock mass depends on the shear behavior of its discontinuities. Several studies have shown that the shear behavior of unfilled rock discontinuities depends on their boundary conditions, roughness characteristics and the properties of the joints walls. Currently, there are several analytical models that can be used to predict the shear behavior of clean rock joints. However, they are all purely deterministic in nature because their input variables are defined without considering the uncertainties inherent in the formative process of the rock mass and the discontinuity itself, i.e., they need an auxiliary tool to consider the variability of their parameters such as the Monte Carlo or Point Estimation Methods. Therefore, the purpose of this article is to present a model to predict the shear strength of clean rock joints incorporating uncertainties in the variables that govern their shear behavior with a zero-order Takagi-Sugeno fuzzy controller. The model is developed based on the results of 44 direct shear tests carried out on different joints. The model input variables are the normal boundary stiffness and initial normal stress acting on the joint, its roughness expressed by the JRC value, the uniaxial compressive strength and basic friction angle of the intact rock, as well as the shear displacement imposed on the joint. The results showed that the predicted shear strength of clean rock joints obtained by the fuzzy model fit the experimental data satisfactorily and helped define the shear behavior of the discontinuity.