Sharif Digital Repository

Emergence of the implantable biomedical microsystems and personal area networks in recent years result in a new class of biomedical systems that requires data transmition in short range at various data rates. Performing with ultra low power consumption and long battery life are crucial in these systems. Therefore, designing low power radios for these systems is still an active research area. Ultera wideband systems are specially considered for implementations because of their potential characteristics.
In this dissertation, different biomedical applications and data communication approaches are surveyed. Then, Different architectures of UWB receivers are reviewed. To implement a low... 

Retrofitting of old mechanical structures by composite materials is one of the most important issues of the world.High reproducing and replacement cost of structures leads to, researchers try to retrofitting old structures and increase their capabilities and so increase their service age. Their research results leads to decreasing cost in one hand and introduce new application of composites in aviation industry in the other hand.Retrofitting mechanical structures show us the important of elements with more stress than the others. The probability of failure is more in these element than the other that we call critical element.These elements in fact are critical parts of an aerial structures... 

There are two viewpoints about pyramid shareholding and cross ownership; first, shareholders want to increase their control over firms. Second, by pyramidal structure and cross ownership, firms internalize weakness of financial market and lack of some financial institutions. In order to identify reason(s) of this issue, we must first recognize affiliated firms and their networks. In this study, we identify firms’ networks in Iran by three definitions: shareholder network, owner network and director network. Then we estimate any correlation between returns synchronicity and being in a same network. Our results show that more than 40% of studied firms are affiliated. Also there is positive... 

The subject of Secret Sharing refers to the methods that a secret information is shared (by a dealer) among a number of parties, so called participants, each having one or more shares, such that the predefined subsets of the participants, called authorized subsets, are able to regenerate the secret using their shares. A more general scheme which is called Multi Stage Secret Sharing (MSSS) is to share multiple secrets among the participants such that the authorized subsets can reconstruct the secrets in the consecutive stages; in these schemes, in addition to the individual shares, the dealer should provide the participants with a number of public values regarding the secrets. A Multi-Secret... 

This research represents findings about obstacles in using value engineering in construction projects of khorasan razavi province via collection of information and views of experts of value engineering.The research shows that the value engineering in the majority of the projects is not practiced and majority of the projects are not benefited from this technique. Many experts believe that lack of required culture and motivation to save up and lack of organisational position for this technique are the main factors for non-progressive use of assessment engineering.The absence of proper understanding of the objectives and place of the value engineering is also an effective factor of on its... 

Machine learning is becoming increasingly popular for solving various problems, and it has become a big part of our daily lives. However, with the use of complex machine learning models, it is important to explain how these algorithms work. Knowing why a model makes a certain prediction can be just as important as the accuracy of that prediction in many applications. Unfortunately, the highest accuracies for large data sets are often achieved by complex models that are difficult to interpret even for the designers. Therefore, the interpretability of machine learning algorithms has become just as important as their accuracy. Recently, different methods have been proposed to help users... 

In 2014, Iranian government initiated “Salamat” universal insurance program, aiming to provide free health insurance coverage for the uninsured population. Consequently, more than 10 million individuals enrolled in the program, and insurance coverage rose 15 percentage points among the urban population. The purpose of this study is to evaluate the program’s consequences on healthcare utilization and mortality of various age-groups. To this end, we have estimated data on healthcare utilization from the results of “Households Expenditures and Income Survey” for years 2011-2017, and also used the data on the frequency of mortality of each age-group taken from the National Organization for Civil... 

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... 

In this work, an improved model for simulating carbonate core acidizing, with the ability of correctly modeling fluid diversion in dual-core experiments is created based on an existing two-scale continuum model. The improvements are applied on the momentum transfer equation, continuity equation, pore-scale structure-property relations and fluid rheology model. Also a more realistic injection scenario and geometry configuration are presented for simulating the diversion experiments. The Darcy-Brinkman-Stokes equation is implemented instead of Darcy’s equation and the continuity equation is modified by adding the mass source term. A global rheology model is developed capable of capturing exact... 

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%... 

Statistical studies indicate the fact that in Iran, like many other developing countries, a significant percentage of buildings are made of traditional materials and most of them are adobe buildings especially in rural areas. Furthermore, geological data indicates that Iran is located in alps-Himalayas seismic zone and exposed by destructive earthquakes and adobe buildings suffer the most damages comparing with other type of the structures. According to these explanations, this research deals with adobe buildings behavior and provides solutions for reinforcing them and improving the seismic response of these buildings. These studies include numerical modeling with finite elements methods by... 

According to the reported field experiences, excess water production from high permeable thief zones of oil reservoirs is the main source of severe operational problems and economic issues. Application of Preformed Particle Gels (PPGs) is an effective technique to overcome this problem. Static test analysis is a primary method for evaluating the performance of PPGs material at different conditions of pH, salinity, etc. However, the effect of the presence of oil and rock on the kinetics of swelling/de-swelling of PPGs is not well understood. Also, considering the vast field application of Co_2-based oil recovery methods, it is interesting to study the effect of carbon dioxide gas on swelling... 

Wettability of reservoir rock is one of the effective parameters in determining the mechanisms of production and consequently the amount of residual oil inside the porous media. In addition, the salinity of injected water is important factor in the recovery of reservoir oil in waterflooding.On the other hand, the role of the hysteresis on the residual oil saturation as well as the flow functions such as relative permeability curves is very important. In this project, the effects of reservoir wettability and injected water salinity on the hysteresis and residual oil saturation in two-phase water-oil flow systems are studied. Core-scale experiments were carried out using sandpacks and were... 

As the reservoir matures, especially in fractured reservoirs, oil production is usually accompanied by the production of some unwanted water. Water production causes environmental problems and imposes high costs on the production system, including the cost of separating water and oil, corrosion of facility, and sometimes, leading to abandoning well. One way to solve this problem is to use gels as a blocking agent. Today, preformed particle gels are used as an alternative to in situ gels, which can solve some issues of in-situ gels, such as uncertainty in gelling time and penetration depth.This research comprises three main parts. In the first part, four samples of preformed particle gels... 

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... 

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...