Sharif Digital Repository

Developing and progressing excavation technology, and distillation and petroleum technology as fuel cause chemical and hydrocarbonic materials have been given an important role in human life. Having petroleum expanded, its effect in countries’ economics has been highlighted and found a substantial role in countries’ development. Iran, considering 11% extractable petroleum reserves which is equivalent to 138 billion barrel, is known as an oil rich country. The petroleum has an eminent role in country’s economics and is the main country’s income source and the most important exports. With regard to the high technology needed for petroleum exploration and purification, Iran requires foreign... 

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... 

Advances in IC fabrication makes possible have systems on chips. In this thesis we have designed and fabricated a digitally controlled bias chip for a transceiver which can be programmed by its digital interface. In this thesis, briefly we review basics of voltage regulators and methods for controlling them. Then we introduce high voltage 0.18um CMOS technology. In this thesis, we describe the requirements of a specific transceiver and present a system to overcome these requirements. This system has positive, negative and internal regulators, a five-bit analog to digital converter, temperature sensors, power amplifier controller and digital serial interface. In this thesis, we present a...