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... 

The error of the inertial navigation system increases over time due to the cumulative errors of sensors. Inertial navigation system couples with sensors or other systems to prevent navigation system errors growth. One of the systems that can be used to couple with inertial navigation system is visual odometry. Visual odometry can calculate relative position of the camera at any time and estimate the device path through input images from one camera (Monocular) or multiple cameras (Stereo). Visual odometry algorithms improvements in recent decade cause this system used as real time. In this thesis, DSO algorithm, which is a direct method and monocular approach, couples with an inertial system... 

Online problems were first introduced in 1980s due to process the data arise from the internet. An Online algorithm is an algorithm which takes a part of input at each step and should give an irrevocable answer before entrance of the rest of data. Online problems are considered when the size of the input is substantial or there are time limitations to wait for the whole input to arrive. One of the first online algorithms discussed was the online bipartite matching. In this problem there exists a bipartite graph with one offline part which is present from the beginning and nodes of the other part entering one by one with all of their corresponding edges. At the entrance of each node the... 

The field of Genome-Wide Asocciation Studies (GWAS) plays a vital role in understanding the genetic basis of complex traits and diseases. In this thesis, the focus is on investigating the effectiveness of two approaches combining Differential Evolution (DE) with Random Forest (RF) and support vector machine (SVM) for feature selection in the context of GWAS. Arabidopsois Thaliana dataset is used as experimental dataset for comparative analysis. The main goal is to achieve more efficient feature selection while maintaining competitive accuracy compared to RF and SVM without using DE. This research includes conducting experiments using DE with RF and DE with SVM followed by a comprehensive... 

Nowadays, increasingly improvements in the digital technology and the advantages of using digital signal processing methods lead engineers to use digital signal processing instead of analog processing in variant domains. However, speed limitations in analog to digital converters (ADCs) and data transfer ports prevent its penetration to high frequency signals region. In this thesis, an Instantaneous Frequency Measurement (IFM) system that can measure frequency in the range of 2-18 GHz is implemented fully digital (DIFM) on FPGA. To do so, monobit sampling technique with the sampling rate of 10 GHz is selected, and GTX high speed serial port is configured to transfer digital data into FPGA.... 

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... 

Optimal resource allocation sustains mobile operators' competitiveness by increasing profitability. Reducing system configuration costs and enhancing accepting new requests to boost revenue provide increasing profitability. A crucial strategy in modern communication frameworks is network slicing, which assigns specific network resources to each customer to ensure its required quality of service (QoS) without interference from other slices. In our study, focusing on the xhaul network structure within fifth-generation mobile networks, we delve into joint optimization of the allocation process across three dimensions of processing, radio, and communication resources to enhance operator... 

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... 

Text summarization and classification are two important tasks in natural language processing. Text summarization involves condensing a piece of text into its main points, making it easier to understand. On the other hand, text classification involves categorizing a text into predefined categories based on its content. Text summarization can be achieved through various methods, such as extractive summarization, where key sentences or phrases are extracted from the original text. The present research aims to classify and summarize news texts in the Persian Daily News dataset. This objective is carried out in two stages. First, the texts in this dataset are classified using the ParsBERT... 

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... 

Genetic heterogeneity within a tumor, which occurs during cancer evolution, is one of the reasons for treatment failure and increased chances of drug resistance. Cancer cells initially derive from a mutated progenitor cell, resulting in shared mutated genes. Throughout the course of tumor formation and progression, the occurrence of new mutations is possible, leading to the generation of cancer cells with various mutated genes. An appropriate approach is to identify the sequence of mutations that have occurred in the tumor, which can be inferred from single-cell sequencing data. Singlecell data provides valuable information about branching events in the evolution of a cancerous tumor. In...