Sharif Digital Repository

The numerical simulation of asphalt concrete and pavement has gained considerable attention in recent decades. Information about the response of asphalt pavements during construction and in-service traffic loading is required by pavement specialists for improvement of pavement analysis and design methods. The goal of this study was to propose a constitutive relationship and a numerical modeling method for asphalt concrete compaction in the laboratory and in situ. Asphalt binders exhibit rate-dependent viscoelastic and viscoplastic mechanical behavior in asphalt concrete. The current study examined the viscoelastic and viscoplastic mechanical behavior of asphalt concrete under various loading... 

In this M.S. dissertation numerical study of slinger fuel distributer has been studied. This type of atomizer has been used in mini turbojets like Teledyne CAE.
The main purpose of this work was obtaining spray structure of slinger atomizers. This goal was achieved by implementing a UDF code in FLUENT® software to model the primary atomization that include variation of fluid from exit of slinger disk bores till formation of primary droplet. In FLUENT® the DPM method and its ability to utilizing Lagrangian approaches have been used. The result of this model is validated by the data from experimental test that can be found in Articles. This is the first time that spray structure of slinger... 

Electric vehicles (EVs) will be used rampantly in future transportation system. Although the uncontrolled charging of these EVs will be threatening for the stability and sustainability of the grid, a well-suited energy trading policy may provide a number of beneficial services to the grid as well as preserving the sustainability of the system along with heightening the performance of operation. In this paper, by taking advantage of block rate tariff, a wholesale pricing policy is introduced. A multi-objective approach is utilized to address the cost reduction and load levelling services, concurrently, in order to guarantee the profits of the both the grid and EVs. Due to the high... 

The process of injecting acid or acidizing, is one of the most common ways to stimulate oil and gas wells. The purpose of this process is to increase the productivity of the well by increasing the permeability of the reservoir rock around the well. This is especially important in carbonate reservoirs due to damage to the formation and low intrinsic permeability in some places. In order to minimize the effects of structural damage, conventional wormhole channels are created to pass through the injured area. One of the important factors in acid validation is achieving optimal injection rate, which means obtaining the highest permeability with the lowest amount of injected acid.Numerous... 

The microstructures of stainless steels consist of an austenitic matrix with almost continuous network of primery carbides.This class of steel had replaced the traditional super alloys with a reduction in costs and has similar properties under conditions of creep, which is one of the principal degradation mechanisms leading to failure in service at elevated temperaturs , therefore, their mechanical properties such as tensile strength and creep resistance are particularly important in hot deformation. Recently the effects of temperature and aging time on static strain aging in worked stainless steel have been investigated. In this study the deformation behavior of HP-series austenitic... 

Many countries use a single water meter for multiple units within a building. This creates a cost externality where the cost of water consumed is spread over all units. Using administrative data from Tehran Water and Wastewater Co. for 2013 and 2014, we find an increase in the number of units on a communal meter on average increases per unit use by 0.4 percent. Estimation at different levels of units reveals that almost all communal meters have higher per unit water use. The results suggest that the externality is responsible for 2.7 percent of water consumption in our sample.
JEL classification: L9, Q25, Q50, Q58
 

According to expanding penetration of Internet and the increased power of processing devices in the recent years, softwares are incisingly used for daily acitivies. The variety of hardware configuration and operating system of such devices leds the companies to take advantage of cross-platform software development methods. Although the production of cross platform software, resude development costs, it results in an specific type of faults known as platform-specific failures. These faults occur when software is running on specific platforms, and therefore, to identify and resolve them, the software test process should be performed on different platforms. To deal with this problem, we present... 

In recent years, the user interface of web-based applications has become more and more complicated. Various technologies, architectures, and tools are being used to create a modern user interface. Users interact directly with the user interface, so its functionality has a significant impact on their satisfaction and it is required to design special test suites for the user interface. Furthermore, we need a method to measure the quality and effectiveness of test suites. An effective test suite is a test suite which is able to detect real faults. But this definition is ambiguous, and hence, not practical. A method called Mutation Testing solves this problem and instead of real faults, uses... 

With the expansion of wireless communication technology and the advent of the fifth generation of mobile communication, there is a growing need for broadband systems. Consequently, RF engineers are currently focusing their attention on broadband transceiver systems. The low noise amplifier (LNA) is a critical component in the receiver of a telecommunication system. In this research, the design of a broadband LNA in the K and Ka frequency band (18 ~ 40 GHz) is presented. The main challenge in designing a broadband LNA lies in achieving simultaneous power matching and noise matching through the input impedance matching network. Various types of broadband impedance matching networks have been... 

The economic activities in a country involved with depletion of natural resources and emission of pollutants and gases to the environment. Depletion of exhaustible resources and environmental pollutions are two determinants of sustainability of development. The present research work is aimed at studying the sustainability of Iranian economy in 2009. The analysis of sustainable development of economy is based the concept of exergy, exergy efficiency and ecological exergy efficiency. Exergy efficiency is the ratio of the exergy of a product in economic activity to the exergy of input streams to that section of economy. Ecological exergy efficiency is defined as the ratio of exergy of product... 

In this project railway industry is introduced as an optimal alternative for transportation in this country. To select the best choice, four railway technologies that have commercial capacity are presented and the most appropriate one is selected with respect to several criteria, including fuel consumption. The purpose of this thesis is to present the best technology in order to improve Iranian railway transportation by considering the shortage of fossil resources as well as pollution.In this project,the copmparison of alternatives and assessment criteria for best technology selection is done by Analytical Hierarchy Process (AHP) and the questionaries are filled out by industry and... 

In this study, integrated navigation systems that utilize velocity-matching algorithm and are used in automatic landing of Unmanned Aerial Vehicles (UAV) are investigated. At first, the accuracy of the navigation system in the landing phase is analyzed and the relationship between the accuracy of inertial sensors, flight parameters and the accuracy of the navigation system is derived analytically. Then, by integrating the dynamic model of the UAV and the inertial measurement unit, a new algorithm for navigation of fixed-wing UAVs is presented. The integration mechanism of the proposed algorithm is tightly coupled; hence, it is capable to eliminate the errors of UAV model and inertial system.... 

Sanctions are one of the most important variables influencing Iran's domestic and international decision-making and have had many effects on Iran's economy and politics in recent years. Iran's ability to influence the oil market and harm the interests of the sanctioning countries in this market raises the question of whether such a capability could affect the outcome of sanctions and lead to the withdrawal of those sanctioning countries. A theoretical examination of the issue of sanctions using game theory shows that if the sanctioned country is not able to retaliate in areas other than the disputed issue, the sanctions game may not reach an equilibrium in which the sanctions are lifted but... 

Governments and organizations need to classify network trac using deep packet inspection systems, by protocols, applications, and user’s behavior, to monitor, control, and enforce law and governance to the online behavior of its citizens and human resources. The high capacity of machine learning in the classication problem has led trac monitoring systems to use machine learning.The development of machine learning-based trac monitoring systems in the eld of research has reached relative maturity and has reached the border of industrial, commercial and governmental use. In the latest trac classi-cation studies using neural networks, as the most ecient machine learning methods, the classication... 

Many lattice-based public key encryption schemes are forced to use long keys. To deal with this problem, structured lattices such as NTRU can be used. Lattice-based searchable public key encryption schemes are no exception. Furthermore, in most existing searchable public key encryption schemes, it is assumed that the user searches documents with only one keyword. However, using a conjunctive keyword search, we can search for documents containing several keywords by executing the trapdoor generation algorithm only once. On the other hand, in most of the published searchable public key encryption schemes, storing and searching encrypted keywords are responsibility of a central entity called... 

The human brain can be described as a dynamic system with multiple subsystems interacting with one another and multi-channel observations of these subsystems are available. The modeling of a system from its observations allows us to gain insight into how its various components interact with one another and also provides intuition about the desired system. Hidden Markov Model (HMM) is a probabilistic model with hidden states that is suitable for modeling these types of systems. Multi-channel observations are available from several subsystems interacting with each other within a general system. In this case, it may be necessary to develop more comprehensive models incorporating multi-channel... 

Object oriented analysis and design hase become the paradigm of choice for many software builders. For, it has filled the gap between the problem domain and its solution. However, most of object oriented methods can not prove their model against the software specification and do not ensure that they realize what the customer needs. Formal method is one of the methods used for building softwares. Since a software is specified accurately by this method, the specification can be used to build the software in addition to being used as a test for the final software. A specification can be refined to code step by step. Since an object oriented model is close to problem domain in real world, a... 

Asphalt concrete is a composite mixture of three phases; aggregate, bitumen and air void. Stress and strain distributions obtained from macroscopic modeling yield different results due to distinctly different mechanical properties of the above-mentioned phases. In this study a more exact analysis of the stress and strain, were carried out by considering the mixture as a two-phase composite; aggregate and mastic phases. Asphalt concrete was considered a composite material consisted of sand mastic and aggregate. Aggregate and mastic phases were separated and response of the loaded asphalt mixture was investigated. Aggregates finer than 2.36 mm in diameter, filler and bitumen consist the... 

The aim of this project is to achieve a semi permeable high flux membrane with a reasonable salt rejection for the treatment of low osmotic pressure water. A thin film composite membrane consists of three polymeric layers was studied in this project. These layers were polyester support, polysulfone sub layer and polyamine selective layer. The polyester support provides the mechanical resistance against the operating pressure. The polysulfone sub layer provides the suitable area for polyamide synthesize, and the polyamide layer is the selective active layer of membrane.
The resistance to water penetration in sub layer was reduced first and then, the pores in the polyamide layer refined by... 

The sulfur compounds in crude oil cause air pollution, metallic equipments’ corrosion and refinery catalysts poisoning like reforming catalysts. Therefore it is necessary to use hydrodesulfurization catalysts for sulfur content reduction. Hydrodesulfurization is the most common desulfurization method in the industry. In this method, sulfur compounds react with the hydrogen in presence of ComMo/γ Al2O3 catalyst and under hard operational conditions like high temperature ( 300-340 ͦC) and high pressure (20-100 atm of hydrogen). Then,these compounds are turned into hydrogen sulfide and hydrocarbons. In the next step, produced hydrogen sulfide will be eliminated from oil cutting.In this...