Sharif Digital Repository

With the advancement of technology, the volume of network traffic has also increased dramatically. The optical network, as the main part of the backbone communication system, plays a significant role in the transmission of network traffic. Due to the limited network resources, an efficient resource allocation in optical networks is required to increase network performance and reduce costs. To solve resource allocation optimization problems, an effective tool is needed to provide a suitable solution in a reasonable time. Resource allocation problems are usually developed on a graph, which is derived from network topology or other properties of the network. As a result, graph-based tools seem to... 

In this thesis, we considered several types of the visibility problem. These problems include computing the visibility polygon of a point observer inside a polygonal domain, maintaining visibility polygon of a moving point observer, visibility coherence in space, maintaining visibility polygon of a moving segment observer and visibility dependent simplification. Furthermore, we considered these problems in both offline and streaming settings. These problems arise in different practical areas, such as computer graphics, machine vision, robotics, motion planning, geographic information systems (GIS) and computational geometry. We obtained effective theoretical results as well as superior... 

The ever-increasing volume of data and calculations has caused a noticeable increase in the importance of computer processing speed. Therefore, topics related to parallel processing as an effective solution in increasing the speed of calculations have been specially investigated and studied. Systolic computing is a powerful approach to parallelize data and perform concurrent computations. Systolic arrays fulfill the goals of the algorithm by directing data flow among different processors and performing minor calculations on them. The slowness and limitations of processors compatible with these arrays, such as FPGAs, have faced many challenges in applying and using their capacities. These... 

Nowadays the evaluation startups has been difficult and this problem increases the likelihood of misunderstanding price of company's stock. Companies need precise evaluation in different steps of their development. during fund-raising, To make the investors’ share determine, the value of companies should be calculated because the investors’ share equals the ratio of new investment to the value of company after investment. Besides, during the merge or possession of a company, to determine the value of the deal or the share of the dealers, we need to evaluate value of the company. to evaluate the Intrinsic value of company, we need to know potential revenue streams, financial statements, the... 

Inverter-based distributed generations (IBDGs) have gained special interest in the electricity supply chain due to the advancements in power electronics technology. Power electronic inverters provide high-efficiency energy conversion with full controllability over a wide operating range, and ancillary services such as reactive power support and active filtering. Considering the voltage and frequency control capability of power inverters, supplying inverter-based micro-grid (IBMG) loads is now pissible. Despite the significant opportunities associated with such sources, they introduce new challenges that should be addressed properly. Reliable and accurate protection against short circuit... 

Telecommunication Company of Iran (TCI), as a government owned company that provides fixed, mobile and Internet services. It is in the process of privatization. In order to be survived in competitive environment, it is required to be an agile and dynamic organization. Also it should be seriously sensitive in profit margin. To be a dynamic company, the management of the company is expecting to introduce a new and modern service named Advanced Communication Services (ACS). This service consists of Video on Demand (VOD), live and archive television programs, tell-learning and e- shopping. For TCI, it's crucial to find a right and precise answer to the challenging question "Will ACS be a... 

The visibility is one of the most important problems in computational geometry. Two points are said to be visible to each other, if the line segment that joins them does not intersect any obstacles. The art gallery problem is a well-studied visibility problem in computational geometry. It originates from a real-world problem of guarding an art gallery with the minimum number of guards who together can observe the whole gallery. In many of applications, the “guards” are “landmarks” deployed in an environment to help provide navigation and localization service to mobile robots. The mobile device communicates with these landmarks through wireless, or other “line-of-sight” signaling... 

With the advancement of technologies such as the Internet of Things the number of devices that are connected to the Internet are increasing rapidly and they continuously generate data that is increasing day by day. Data generation rate in these devices can be so large that practically the existing hardware has not the ability to store and process all information related to that data in appropriate way. In this situation, streaming models become more important. In the stream computing models, online processing of these data are implemented with memory complexity of O(1) . Stream algorithms refers to algorithms that input data is in the form of streams. Data appear and are removed from the... 

When heart failure occurred, revascularization to body’s organs and consequently covering the metabolic demands of different sections faces with problem. Chronic heart failure is the first reason of mortality all over the world. Traditional treatment for CHF at end stage is heart transplantation. But some of patients don’t have the opportunity to benefit from heart transplantation because of aging, health conditions and lack of donors. On the other hand, Left Ventricular Assist Devices that are using for supporting a ventricle suffering from failure face with basic chalanges for example, backflow in lower speeds and suction in higher speed. These constrictions necessitate maximum and minimum... 

With the implementation of the targeted subsidy plan in Iran and as a result, the allocation of cash subsidy to individuals, the effect of this policy on labor supply behavior can be studied. In most of the researches, the degree of the effects of implementing such policies on the working behaviors is studied.
In this research, after discussing some proposed models of labor supply and the effects of nonwage income on that, we reviewed the history of implementing such policies and their outcomes in different countries. Then, the possible methods of studying this issue in Iran were discussed. Finally, using a part of the household budget data in years 1389 and 1390, a panel data was... 

In the early 21st century, Iran established its wholesale electricity market as part of the restructuring of the power industry. Currently, the majority of electricity trades occur in this market. The simultaneous production and consumption of electricity, along with constraints for new companies to enter the market, make exercising market power a significant consideration in the economics literature. The market mechanism is based on auctions and is supported by a rich-data environment that allows for monitoring of production firms' behavior. This research measures the exercise of unilateral market power in Iran's wholesale electricity market using three months' worth of data for each year... 

Finding a path between two specified points is one of the most common problem in computational geometry. The minimum-link path problem is in this category. The minimum-link path between two points is the path between these points with the minimum number of segments. Minimum-link paths have application in areas such as computer graphic, geographic information systems, robotics, image processing, cryptography and VLSI.In this thesis we study variations of the minimum link path problem. Specifically we consider the constrained minimum-link paths in which the path must passes through some given
regions. We detected a flaw in a previously presented algorithm and propose a method to fix this... 

Ising model. It means that the partition function of each lattice model is equal to the partition function of 2D Ising model. This completeness is proved by using concepts and techniques from quantum information theory and is based on the universality of cluster states. We have now proved this important result, by using independent and general concepts and methods which are accessible to a wide audience of researchers across many disciplines. Furthermore, our method has the advantage of eing algorithmic in nature so that, by following a set of simple graphical transformations, one is able to transform any discrete lattice model to an Ising model defined on a (polynomially) larger 2D... 

Structural efficiency is a primary concern in today’s aerospace and aircraft industries. This brings about the need for strong and light weight structures. To increase the strength of a panel without considerable increase in its weight, we may use a lattice of stiffeners which may have shells connected to one side of the lattice or both sides of it. These structures are usually called grid stiffened structures. Aircraft fuselage and launch vehicle fuel tanks are some of the many applications of these structures in aerospace and aircraft industries. These structures include two major groups; isogrids (grid stiffened structures with equivalent isotropic properties) and orthogrids (grid... 

In this study, we intend to examine the effect of physicians’ leisure and parents’ preferences on the choice of the date of C-section. According to the literature, the comfort and convenience of the physician is one of the main factors contributing to the fact that less C-sections are scheduled on weekends compared to other days. On the other hand, avoidance of C-section on the 13th of the month as well as increase of C-section on certain special dates has been observed in different counties. In this study, we use national birth data in Iran from 2013 through 2017. During this period, cesarean rate was about 50% nationwide. According to the results, C-section is reduced by 72%, 42% and 12%... 

Membrane bioreactor (MBR) is a combination of conventional activated sludge (CAS) and membrane filtration which owing to its advantages such as high quality effluent and low excess sludge production, has gained increasing application in wastewater treatment. The major drawback of a MBR is the membrane fouling that reduces the permeate flux, which in turn increases the overall operational costs due to high energy requirements. In existing study, the combination of sludge oxidation and coagulation/flocculation addition was investigated for mitigation of membrane fouling in a membrane bioreactor. Oxidation can facilitate sludge flocculation and hence improve the properties of mixed liquor. The... 

Producer-level data for Iranian manufacturing firms shows a large amount of dispersion and concentration in producer level sectoral shares, as well as a very strong relashionship between sectoral shares and markups. We Study the pro-competitive gain from trade in the Iran’s manufacturing sector. Domestic firms in Iranian manufacturing sector are protected via tarfiff and non-tariff barriers enforced by the government. In many sections of manufacturing sector, domestic firms feel little competition and charge high markups. The market power of domestic firms could be reduced by the reduction of tariff rate and increase in import share. As a result of foreign competition pressure, they would be... 

The relationship between the environment and human life has long been considered by researchers. Technological growth in the last century, by the intensification of natural resources usage, led to environmental degradation, and thus the importance of recognizing the relationship between human life and the environment has doubled. The present dissertation is organized in three chapters, in each of which we investigate the impacts of a dimension of environmental degradation on human well-being.In the first chapter, we investigate the effect of drought on expenditure and income per capita of Iranian households. To do this, we combine the expenditure and income data of more than 600,000 urban... 

This thesis develops a multi-market equilibrium framework for analyzing retail electricity markets, with a focus on the interaction between the forward and spot markets under conditions of network uncertainty and renewable integration. We explore `the role of retailers’ hedging strategies, forward contract demand, and their impact on market efficiency. By modeling the forward price and the retailer’s optimal forward position under mean-variance preferences, we derive key equilibrium conditions for the spot, forward, and retail markets. Our results show that an increase in uncertainty leads to lower hedge ratios, even in the face of higher price variance. Numerical simulations using Monte...