Sharif Digital Repository

Today, we live in an information age where all people can access the vast amount of data in the world by connecting to the Internet.Since the Internet has expanded significantly to share information, some individuals and organizations seek to be able to prevent the possible sabotage of some people by monitoring network users. Analysis of computer network traffic is one of the importance issues that many activities have been done in this area. One of the most important questions in traffic analysis is to identify the main content of traffic on the encrypted network. Numerous studies have shown that the traffic of websites visited through the Tor network, including Specific information that... 

Adaptation is a recurring phenomenon in biology by which biochemical systems can robustly- and in some cases completely- adapt their regulated outputs to en- vironmental disturbances and uncertainties. In nature, such a feature has been evolved in biological circuits through the construction of integral feedback control structures. Three types of biologically plausible controllers have been recently in- troduced which can ensure the existence of robust perfect adaptation for arbitrary plants. In this thesis, the main purpose is to have a comparison between them. To this end, we first find a stability criterion to relate the system’s stability with its internal parameters. We then calculate a... 

In this study, the nonlinear vibrations of an elastic rotor that is under the elastic support and under the follower force caused by the airflow passing through the rotating plane are investigated. The elastic shaft is modeled by the Timoshenko beam theory, which is connected to a motor through a flexible coupling and the motor increases the rotational speed of the rotor by applying torque. Gibbons’ equations have been used to model the misalignment forces. First, the kinetic energy of the rotating system is calculated nonlinearly to take into account the effect of nonlinear terms due to the rotational inertia of the system, and then the potential energy and The work of external forces on... 

Path planning is essential for unmanned aerial vehicles (UAVs) to navigate complex and hazardous environments. Many algorithms have been proposed to solve this problem, but heuristic, meta-heuristic, and hybrid algorithms have recently gained attention due to their ability to find approximate solutions quickly. In this thesis, we propose using the Late Acceptance Hill Climbing (LAHC) algorithm for UAV path planning. We compare LAHC's performance to classical and state-of-the-art optimization algorithms, including simulated annealing (SA), grey wolf optimization (GWO), symbiotic organisms search (SOS), and simplified grey wolf optimizer-modified symbiotic organisms search (SGWO-MSOS).... 

The price elasticity of gasoline demand is a key parameter in evaluation of various policy options. However, most of the literature uses aggregate data to identify this elasticity. Temporal and spatial aggregation make elasticity estimates unreliable. We employ a unique dataset of all gasoline transactions in Iran during a four-month period around an unexpected exogenous price change to identify price elasticity. After controlling for date and individual fixed effects we estimate a robust significant price elasticity of -0.127. Aggregation of the same data by week, month, and city yields an estimate of -0.3 indicating a significant bias in earlier studies. We also identify a significant... 

Examining composite quantum systems through quantum thermodynamics, we face the new concept of binding energy. In this thesis, we are going to present a general definition for binding energy in quantum systems which covers any kind of interactions. First of all, we examine the possibility of energy exchange in a quantum system using quantum thermodynamics. In this theory, energy exchanges of an open quantum system may be divided in to two portions: heat and work; due to an accepted definition, heat is the portion of energy that is supposed to change entropy, while work has no influence on that. In this research, we restrict our calculations to the systems which are thermally closed and... 

Bathymetric maps are used for monitoring water bodies such as lakes, wetlands, and coastal areas, providing valuable information regarding changes in water storage volumes in these environments. For lakes prone to drying and salinity issues, where the lakebed elevation is constantly changing, the importance of these maps becomes even more pronounced as they play a crucial role in monitoring these lakes' conditions and assessing restoration efforts. Various methods exist for generating bathymetric maps, one of which is satellite remote sensing, which is more time- and cost-effective than traditional methods. One of the most common and accessible types of remote sensing data used for... 

In this study, we investigate the phenomenon of price manipulation in rights offering transactions using the data of share capital increase, price and ownership of firms in Iranian capital market. We find that blockholders reduce the share price by selling stocks during the rights trading period and then buying the rights at lower prices. We further find that the shareholders who bought the highest amount of the rights tend to sell a higher percentage of shares during the trading period, and the cumulative abnormal return is inversely related to the rate of sale of these blockholders. We also observe that the probability of price manipulation is higher for stocks with lower liquidity and... 

The present study deals with the development of development of fragility curves for confined masonry buildings with the emphasis on masonry school buildings by means of numerical simulation. In doing so and based on the results of several previously-performed tests in Iran, simple analytical models for confined masonry walls capable of predicting various failure modes and also simulating different behavioral characteristics of these walls in the form of cyclic force-displacement curves were presented. In order to endure the ability of the proposed analytical models in simulation of seismic response of existing confined masonry buildings, a static-cyclic in-situ test on a real typical... 

Adobe buildings on one hand are very heavy and hence generate great amounts of inertia loads during earthquakes. Their response is also amplified in the high-frequency earthquake waves due to great stiffness. On the other hand, these structures proved vulnerable during past earthquakes because of low strength and ductility. Considering the fact that there are too many structures of this kind throughout the country and a majority of their residents are the poor, seismic retrofitting of these building should be taken as a priority rather than reconstruction. It is obvious that the proposed retrofitting technique should be simple, feasible and economical, as well. Among possible retrofitting... 

Sports scheduling with its interesting theory and application has been the subject of many research recently. Different problems arise from different league structures with different objectives. Inspired by the structure of soccer leagues in Britain and Netherlands, we study structures in which a different permutation of first half-season rounds is played during second half-season. Some leagues like Premier league in addition to this structure have a special property in which two teams may do not play against each other in the first half-season and play twice in the second half-season. Therefore, we study both structures separately. We present a mathematical model to cover both structures.... 

Based on the modified couple stress and Mindlin plate theories, a Levy type solution is presented for bending and vibration analysis of rectangular isotropic micro plates with simple supports at opposite edges and different boundary conditions at the other two ones. Modified couple stress theory is taken into account to capture the size effect and the governing equations are derived using Hamilton's principle, and solved by Levy solution and space-state method. The results are verified with the existing ones in the literature. As a benchmark, additional tables for vertical deflections and free vibrations of plate with various boundary conditions are presented  

Sharing the values resulting from the purchase and sale of energy in large coalitions in smart grid systems is accompanied by computational complexity and high calculation time. In order to reduce this time, this research presents novel clustering approaches to simplify the process of value sharing among players. These approaches have been employed in two methods: Shapley values and worst-case minimization (Nucleolus). In this method, players are clustered based on their roles and assets, and the K-means algorithm is also used for the second clustering method. By doing so, the constraints and the number of possible coalitions are reduced, and consequently, the calculation time in both... 

With the increasing development of Internet of Things (IoT) devices, issues such as establishing effective communication, optimizing energy consumption, ensuring reliability and improving the quality of services provided by these devices become more and more complex and critical challenges. With the introduction of fog computing model by Cisco in 2012, some of these challenges were successfully managed. Fog computing is a distributed computing paradigm that acts as a middle layer between cloud data centers and IoT-based devices/sensors. By distributing computing resources closer to edge devices, fog computing enables real-time data processing and analysis. However, one of the key aspects in... 

Modern sensors consist of arrays of detectors specially arranged to enhance precision, capabilities, and field of view (FOV). Sensor arrays can have multiple functionalities such as the simultaneous detection of position and motion. We use a linear sensor model and develop an optimization method to design an array of photodiodes. Our objective function minimizes bias and variance estimations. We introduce a maximum likelihood technique to approximate and determine the bias caused by measurement errors, and verify our theory by statistically complete simulations. We apply our theory to design an optimal sun sensor. The sensor has a predefined conical FOV, and its accuracy is controlled by a... 

Condensation from a gaseous phase is a common method for the fabrication of metallic nanoparticles. Electromagnetic induction furnaces are the most common equipment used for this method. Since the sample doesn’t touch any foreign object, this method is one of very few ways to synthesize ultrapure nanoparticles. However, a major setback of this method is its low production rate.One of the only workarounds to this issue is to increase the melt’s surface area so as to present a larger surface for evaporation. In the common setup for this furnace the molten sample takes on a spherical shape which unfortunately holds the lowest surface to volume ration of any shape. The endeavor in this study has... 

As the Business environment becomes more and more competitive, companies are forced to push themselves to use their capabilities in order to gain success. The success of the companies depends on their business knowledge and the strategies they use to compete in global market. The purpose of this study is to examine the attitude of consumers towards Beem products in Iran and the potential customers’ attitude toward home appliance product in Arab State of Persian Gulf (ASPG) in order to define the most proper strategy of adaptation to enter into an international market and increase the market share in a new environment. Quantitative methods have been chosen for gathering data. Two sets of... 

In recent two decades, with developments in micro and nano scale fabricating techniques, use of microfluidic systems is increasing in different fields. How to drive fluid is a hard question because of high pressure drop in micro scale. Different methods has been suggested to solve this problem, among which, electroosmotic pump is preferred because of its advantages. One of the main applications of microsystems is in biomechanical devices like microreactors which are usually working with non-Newtonian fluids. The cross section of these devices are most often close to rectangular shape.Therefor, in this study,Hydrodynamic charactristics and mass transport of non-Newtonian fluids under... 

In wave theory, it is conventional to divide media into reciprocal and non-reciprocal types. The Lorentz reciprocity theorem is the most prominent theorem in electromagnetic theory. One wave phenomenon that can be explained by the reciprocity theorem is unidirectional waves. These waves are well-known in the literature and have diverse practical applications. However, in this research, we explore some curiosity-driven questions regarding their behavior near barriers. We hypothesize that new applications might be discovered for these waves. In summary, we analyze the behavior of unidirectional waves when they encounter barriers. The main question is: if unidirectional waves cannot propagate... 

Thread the bearing capacity of soil beneath the foundations of the main topics in Engineering is considered that main reason it is the more contact structures. if all the factors that are likely to impact on bearing capacity is more useful to consider more accurate results are obtained. This thesis has tried using FLAC software is a comprehensive review on the soil bearing capacity of foundations under certain conditions of Geotechnical and foundation strip, can be done .The modeling of soil layers and soil bearing capacity based on changes in properties (clay and sandy soils) and changes in depth are examined. The changes in the deep layer of soil and properties of soil, bearing capacity is...