Sharif Digital Repository

A decade after discovery of graphene, the unique properties and characteristics of two-dimensional materials, particularly an emerging family of carbides and nitrides (MXenes), have attracted the attention of researchers. MXenes are two-dimensional structures of two or more layers of transition metals, with interstitial carbon and/or nitrogen atoms, with exceptional properties such as high specific surface area, excellent elastic modulus, metallic conductivity, and various termination groups. These properties can be altered by various factors, including chemical composition and synthesis processes, and any changes in these factors significantly affect the properties of MXene sheets. In this... 

Ultralight aircraft (VLA category) are usually piloted by novice pilots under Visual Flight Rules (VFR). In this work, we demonstrate how newly developed techniques in robotics could be used to enhance flight safety in this category of aircraft, especially during landing around sunset. In this research we have investigated the ability of Simultaneous Localization And Mapping (SLAM) algorithms in low level flight just before touch-down. Different case-studies show that SLAM algorithm is efficient in detecting the runway threshold. Comparing five different methods of parameterizations for landmarks detection including: (1) Plucker, (2) Anchored Plucker, (3) Homogeneous, (4) Anchored... 

The task of keyword prediction has been widely used in the field of natural language processing from past to present. In the past, keyword prediction was primarily performed on textual content. However, with the rapid growth of multimedia content and its use in social networks, the need for extracting and automatically generating appropriate keywords for videos has also increased. The use of suitable keywords significantly impacts content accessibility, visibility, and better classification. With the expansion of generative models, the keyword estimation problem can also be formulated as a text generation task. The proposed solutions have often focused on English-language content, and they... 

The amount of fresh water suitable for various uses is decreasing day by day. This may be due to evaporation or contamination of water or such. Heavy metal cations, dyes, oils and solvents are the most important substances that contaminate water. There are various ways to remove these contaminants, one of which is the absorption of these substances by suitable absorbents. Carbon compounds have attracted much attention among all the absorbents used so far. The aim of this study is to produce carbon aerogels from an economic and modify its structure and properties by adding graphene nanosheets. In this study, Novalak-graphene oxide (GO) gel was fabricated using solvent-saturated vapor... 

Type IV high pressure vessels are composite vessels with a polymeric liner, which are the best choice for storing hydrogen in hydrogen vehicles. The defect of these vessels is the penetration of light hydrogen molecules in the polymeric liner and the composite part. When depressurization the vessel, these molecules cannot release from the polymeric liner and the composite part according to the emptying rate of the vessel. Thus, concentration of the hydrogen molecules in the polymeric liner becomes more than inside the vessel which leads to a pressure difference between the two sides of the polymeric liner that causes the liner collapse. In this research, the partial differential equation for...