Sharif Digital Repository

The velocity of the hot outflow gas in laminar premixed flame is one of the important properties of combustion, along with other properties such as temperature and flame components. In fact, laminar flame velocity has been employed in a multitude number of concepts ranging from engine design to achieving flame properties under turbulent conditions. In this research, a cylindrical Bunsen burner and appropriate TIO2 particles were used. Particles with diameters between 10-23 microns were used and the exit diameter of burner considered 14 mm. In this study, the equivalence ratio with a value between 0.9-1.2 are fed with LPG fuel to create a laminar premixed flame. As a result of the present... 

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... 

Technology advances in the era of wireless communications leads to the birth of a very useful network called Wireless sensor Network which is very interesting for scientists and researchers. While these networks consist of tens to thousands of tiny sensor nodes, they consume their energy from none-rechargeable batteries. Reducing energy consumption and extend the life of network is the most challenging requirement for these kinds of networks; in some environments like military training which precision and sensitivity are critical, it might take at least K sensors to cover the whole area and these conditions leads to a vast data repetition in network and as a result energy exhaustions in... 

This research introduces a novel thermo-mechanical multiscale technique, utilizing machine learning, for simulating the compaction process of aluminum nanopowders with surface oxidation at various temperatures. The methodology employed involves the utilization of nonlinear thermo-mechanical Finite Element Method (FEM) for macro scale analysis, while employing the Molecular Dynamics (MD) method to calculate the mechanical and thermal characteristics of aluminum nanopowders at the nano-scale. The first part of the research presents a comprehensive study on the thermal conductivity of alumina-coated aluminum nanopowders, which is a crucial property for their application in powder metallurgy,... 

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... 

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....