Sharif Digital Repository

Traveling wave thermoacoustic prime mover is studied in this project. For this purpose, based on one dimensional thermoacoustic equations, thermoacoustic flow is modeled in each segment of thermoacoustic systems. Since regenerator is the most important segment in a traveling wave thermoacoustic prime mover, modeling of the flow in regenerator is considered as the primary motivation for this research. In order to model the thermoacoustic engines, governing 1D relations are simplified and developed. Moreover, to solve equations in regenerator, tortuous geometry of regenerator is approximated with the stack consisting of circular pores. Therefore, in this research stack relations has been used... 

Cells in their surrounding environment subjected to biochemical and biomechanical stimuli and respond to this signals. The mechanism by which cells transduce external mechanical signals into responses is called Mechanotransduction and cell use this mechanism to sense and respond to extracellular signals. Cells control processes like migration and division by mechanosensing. Cell migration is one of the most important responses to Cell-ECM interaction. This migration underlies many biological processes including embryogenesis, wound healing, tumorogenesis, morphogenesis and immune defense, so the study of cell migration is of particular importance. If there are external signals in cells... 

Additive manufacturing (AM) has gained significant attention in recent years as a novel approach to fabricate three-dimensional parts. Its advantages, including high speed, low-cost production for small-scale batches, and greater design freedom, have made it a competitive alternative to traditional manufacturing methods. However, the application of AM for components subjected to fretting fatigue requires careful evaluation. Fretting fatigue is a major cause of failure in turbines, particularly at the contact interface between turbine blade roots and disk. In this study, the influence of AM and post-processing treatments on the fretting fatigue life of Ti-6Al-4V alloy was investigated. Five... 

Existing face forgery detection methods mainly focus on certain features of images, such as features related to image noise, local textures or frequency statistics of images for forgery detection. This makes the extracted representations and the final decision depend on the data in the database and makes it difficult to detect forgery with unknown manipulation methods. Solving this challenge, which is called the generalization challenge in artificial intelligence literature, has become the main goal of researchers in this field. In this thesis, the focus is on extracting effective features for success in forgery detection and preventing the performance of the forgery detection network from... 

One of the most important problems in machine learning is investigating the performance of the learning algorithms, and especially deep neural networks, on adversarial examples, which are generated by imperceptibly perturbing input images, so that cause the model make a wrong prediction. Not only this line of research is important for making deep neural networks dependable, but also can help with understanding the fundamental limitations of deep neural networks, and the nature of their operation, which can in turn provide researchers with valuable insights into artificial intelligence. In this research work, we have tried to approach the topic with a mainly theoretical mindset. The method we... 

Wind energy technologies guarantee low pollution and operational costs. Using a DFIG and a fractionally rated power electronics converter gives variable speed operation with a low cost drive train. As energy policy organizations have allocated a considerable quota of wind energy generation to offshore wind farms, the absence of slip rings and brushes in the brushless DFIG (BDFIG) is an advantage for offshore wind turbines where maintenance is vital and expensive. With increasing wind power penetration in power systems, grid code requirements are an important consideration for the ride-through capability of wind farms through voltage dips, particularly for multi- MW wind turbine generators....