Intelligent Fault Diagnosis of Wind Turbines Using Adaptive Fuzzy Threshold

Wind turbines are exposed to a variety of faults some of which can cause irreparable economic losses. Therefore, identifying the faults in a short time, ensures the correct operation of the system and prevents the mentioned losses. In this paper, using a dynamic model for wind turbines which includes mechanical and electrical parts with appropriate details, an intelligent fault detection and isolation system is designed utilizing recurrent neural networks. The proposed system can identify the occurred faults in pitch sensors and pitch actuators. Then, in order to consider the robustness of the system, it is suggested to use an adaptive fuzzy threshold in decision making block. Simulation results for the fixed threshold, robust thresholds, and the proposed adaptive fuzzy threshold validate that the suggested adaptive threshold reduces the detection time. In addition, the number of false alarms, and the number of missed ones are reduced by using the intelligent fault detection system

Multiscale modeling of material failure: Theory and computational methods

Material behavior and microstructure geometries at small scales strongly influence the physical behavior at higher scales. For example, defects like cracks and dislocations evolve at lower scales and will strongly impact the material properties (mechanical, electrical, thermal, and chemical) at the macroscale. We summarize the recent developments in computational methods to simulate material behavior on multiple scales. We provide details on different techniques at various length scales: quantum, atomistic and coarse-grained models, and various continuum-based models. Furthermore, multiscale methods are broadly divided into: hierarchical, semiconcurrent, and concurrent techniques, and we review a number of modern hierarchical and semiconcurrent multiscale methods such as virtual atom cluster model, homogenization techniques, representative volume element-based methods and structural reconstruction based on Wang tiles. We also go through popular concurrent multiscale methods for fracture applications, such as extended bridging scale and extended bridging domain methods and discuss in detail adaptivity, coarse graining techniques, and their interactions. Computer implementation aspects of specific problems in the context of molecular as well as multiscale framework are also addressed for two- and three-dimensional crack growth problems. The chapter ends with conclusions and future prospects of multiscale methods