Sharif Digital Repository

The primary objective of this thesis is to provide solutions addressing some security loopholes in continuous variables quantum key distribution protocols. The coherent detection method is utilized in this particular quantum key distribution scheme, which is a phase-sensitive detection. To measure in the quantum noise limit in the detection part, we need a local optical oscillator, which must possess a high intensity and a consistent phase correlation with the quantum signal. Therefore, reconstructing the emitter’s reference phase in the receiver’s detection system is considered as one of the most critical challenges in these protocols. In order to attain this goal, in the early versions of... 

In this thesis, we introduce a novel Artificial Intelligence (AI) system inspired by the philosophical and psychoanalytical concept of imagination as a ``Re-construction of Experiences". Our AI system is equipped with an imagination-inspired module that bridges the gap between textual inputs and other modalities, enriching the derived information based on previously learned experiences. A unique feature of our system is its ability to formulate independent perceptions of inputs. This leads to unique interpretations of a concept that may differ from human interpretations but are equally valid, a phenomenon we term as ``Interpretable Misunderstanding". We employ large-scale models,... 

According to today’s medicine progress, the need for improving the medical facilities have been increased. Within the human body, the biomolecules concentration gradient is regulating the cell functions. Biological processes such as immune response, wound healing, and cancer metastasis have been affected by the bimolecular concentration gradient. So understanding the cell behavior in the presence of a chemical gradient can improve the understanding from these biological processes, and also would help in medical researches. On the other hand, finding the appropriate dose of the drugs and in some cases finding the most effective drug is a clinical challenge that made a new field of research in... 

The development of clean, renewable and alternative sources of fossil fuels has increased in recent years due to various factors such as environmental pollution, reduced fossil fuel resources and increased energy consumption. The application of microbial fuel cells is one of the clean energy production methods using renewable sources such as municipal sewage. The microbial fuel cell converts the chemical energy stored in organic materials into electrical energy and simultaneously purifies the sewage. Increasing current density and power density are the most important challenges for microbial fuel cells. In this study, the two biocatalysts of Shewanella Oneidensis MR1 and Escherichia coli... 

During fuel combustion, aromatic sulfur compounds in energy fuels convert into sulfur oxides, which cause major environmental problems such as acidic rain, global warming, and air pollution. Absorption desulfurization is one of the promising and economical methods to remove these sulfur compounds from fuels. Metal-organic frameworks (MOFs) are a class of nanoporous materials that are of interest for use as adsorbents due to their high specific surface area, unique surface adsorption properties, high adsorption capacity, tunable porosity, flexible dynamic behavior, and diversity in functional and metal groups. In this research, we first synthesized five metal-organic frameworks, namely... 

In this research, molybdenum and tungsten catalysts modified with cobalt and nickel on a carbon support have been synthesized and investigated in the oxidation desulfurization process. A model fuel was used to evaluate the synthesized catalysts. This model fuel was n-decane. dibenzothiophene was also used as a sulfur model. The synthesized catalysts were subjected to various analyzes such as XRD, FTIR, Raman, BET-BJH, NH3-TPD, TEM and ICP-OES for structural evaluation. On the other hand, synthetic parameters such as metal loading rate, molar or weight ratio of secondary metal (cobalt and nickel) to primary metal (molybdenum and tungsten) and molar ratio of citric acid to primary metal as... 

In recent years, dust pollution has become a worldwide issue due to the creation of serious environmental problems and the effects it has on human health. In this research, an environmentally friendly soil stabilizer has been synthesized, and its performance has been investigated. Acrylamide monomers were grafted onto sodium lignosulfonate chains, utilizing solution polymerization. The soil of the Ahvaz deserts was used in the analyses. Using EDX and DLS analyses, the components of this soil and the particle size distribution of the used soil were obtained. Characterization of the functional groups and the structure of the graft copolymer were done by FTIR and H-NMR analysis, respectively,... 

Environmental regulations with respect to the marine diesel emissions have become stricter during recent years, thereby imposing traffic limitations on Iranian ships preventing them to enter emission control areas. Nitrogen oxides (NOx), as one of most important air pollutants, have adverse impacts on public health and ecosystem, so as the ships are the primary source of NOx internationally, the after-treatment system finds more urge to be developed. In this study, a NOx reduction system using non-thermal plasma technology is studied in order to determine its application and efficiency for NOx removal from the exhaust gas of Iranian marine diesel engines. Meanwhile, important factors were...