Sharif Digital Repository

The rapid growth of information on the web and the need for information sharing on one hand and also as news plays an important role in our life and internet becomes the biggest repository for keeping this news on the other hand, lead us to research in this domain.
In this thesis, we introduce a new framework for searching news by considering the relation between news and events. This framework called NewsSe. NewsSe considers news as a series of events in order to cover all aspects of news. NewsSe uses Domain Ontology and Event Ontology to extract the concepts and relations existed in news. NewsSe consists of 4 different modules. NewsCr is a crawler which uses a new methodology for... 

Today for many applications, traditional encryption systems is insufficient to find a way for them. Traditional methods have limited access to the encrypted data, as it is ”all or nothing” decryption. To overcome these limitations, some primitives such as searchable encryption, identity based encryption, attribute based encryption, predicate encryption and so on were introduced. They enable fine-grained access to encrypted data. In fact, they enable sender to control over who has access to the encrypted data and what they can learn.Functional Encryption is a general concept that these primitives can be special cases of it. Dual System Encryption opens up a new way to prove security of... 

In most places in the world as it is in our country, structural vibration caused by earthquakes are among the most destructive menaces for the building. For this reason one of the main goals for civil engineers is constructing structures that can perform properly in an earthquake-exposed situation. For moving toward this goal it is necessary to estimate structural responses considering probable earthquake excitation and use these data for design of new structures or retrofitting of existing ones. In this research, the capability of a new method named Endurance Time analysis in seismic assessment of concrete moment frame is investigated in nonlinear range. ET is a new dynamic time history... 

Preventing critical damages to structures and hence saving the lives and money is an inevitable work which a designer has to do. During the earthquake, huge amount of energy applies to the structure and finding a way to reduce transfer of this energy to main structure is crucial. For this purpose, Structural Control systems may be used. Metallic Dampers are one of those systems which absorb the earthquake input energy by having nonlinear deformations. In this Thesis, one type of this dampers which is innovated by Estekanchi, have been studied .Indeed, this damper is a connection between bracing and main frame. In this damper a U shape part acts as a sacrificing portion and absorbs energy by... 

The purpose of this study is to evaluate the performance and seismic costs for pre-designed bridges according to the Iranian Bridge Code, which maps and details are available in Code 294. In order to evaluate performance, seismic costs of a structures are determined over its life cycle and these costs are compared eventually. Seismic costs are divided into two parts of the initial cost and life cycle cost of the structure. The initial costs depend on the cost of constructing the bridge, but life cycle costs are depends on seismic damage for structure and its users over the useful life of the bridge. These damages include the cost of maintenance of the bridge over its useful life and the... 

Elevated concrete tanks have a wide range of applications in storing drinking water, firefighting, sewage, oil, toxic chemicals, and similar fluids. Therefore, due to their usage, these tanks are usually placed in the category of very important structures and vital arteries. Consequently, their design against seismic loads and their proper performance during earthquakes are of great importance. The endeavor time Analysis is a seismic analysis method in which the structure is subjected to an increasing dynamic excitation whose intensity gradually increases over time. The structure's response over time is examined, and based on the corresponding response to various levels of excitation... 

The development of a complex software needs an abstraction mechanism which is called Model Driven Engineering mechanism. In order to have a successful model based process, we need an appropriate tool such as version control systems to support our model-based process. On the other hand, developers need a mechanism to synchronize them with VCS systems. One of the concerns in modeling languages is the compatibility and the consistency of the models and modeling languages during their evaluation. the focus of the former researches was mostly on the consistency of the models during their evaluation, and to this end, lots of approaches have been proposed for keeping the consistency of the models... 

Nowadays economical issues are greatly taken into consideration. In this project we aim to study a problem of this area, which focuses on the subject of location allocation and pricing strategy for a good supplier. Solution evaluation is done by taking costumer demand into account. This problem has a sequential characteristic. That is players do not take their decisions at the same time. Suppliers should first decide about where and how they plan to provide their goods. On the other hand almost every economical problem have multiple players who play with or against each other. Therefore modeling this problem using Stackelberg leadership model is a natural choice. Since this problem is in the... 

Preventive maintenance strategies have been considered by highway agencies in order to increase pavement service life and to reduce the costs associated with pavement maintenance. Due to the increasing concern regarding promoting sustainable pavements, consideration of the environmental, economic and performance factors in devising preventive maintenance strategies is of great importance.This study contributes to developing a multicriteria decision-making tool for sustainability evaluation of pavement preventive maintenance strategies. The developed tool, PaveSAT, considers the greenhouse gas emission, net present value, and pavement performance to rank preventive maintenance schemes using... 

In this thesis, the effect of cognition in wireless networks is studied. In a wireless communica-tion network, cognition is the ability of a device to sense the transmissions of neighboring nodes and adapt its own transmission to the sensed environment. Cognitive radios are very attractive be-cause of the increasing need for more efficient use of frequency spectrum. The goal of this thesis is the analysis of cognitive radio networks from an information theoretic perspective and to this end statistical models of the wireless medium with a limited and tractable number of devices are uti-lized. We consider three different models in three parts of the thesis. First, we consider a new... 

The use of Radio Frequency Identification is increasing rapidly. The reason is the capability to transfer data wirelessly without line-of-sight necessity, high data rate and long read range. The main advantage of barcode is its lower cost which has ensured its existence for many years. The applications and materials that are identified by RFID increase as the price of RFID tags decrease. This Project deals with the front-end of an Integrated RFID Reader for the UHF band. The bottleneck of the design is the presence of a large interferer just hundreds of kilohertz apart from the desired signal which is at about 900 MHz. The key idea of the design is utilizing feedback in order to cancel... 

The attention to ice accretion subject and its implementation have recently become very serious in our country due to a substantial need to a further understanding of this phenomenon and improving the design and construction of anti-ice systems for the airplanes in-hand. The subject of this study is the numerical simulation of ice accretion at the surface of airplanes, which is a technical approach in aerospace engineering. In other words, this study simulates the details of ice growth at different sections of an airplane wing considering wide ranges of different affecting parameters and conditions. To achieve this, we numerically solve the governing equations for two-phase flow of air and...