Sharif Digital Repository

One of most important type of dams are concrete gravity dams, This structures maintain their stability against the load from their weight. The study of stability of dams is very important issue because Iran is placed on a seismic zone and instability of constructed dams will cause many problems for us. There are two method in study of concrete gravity dams: in first method which is named rigid approach the body of dam consider as a rigid body and by equilibrium equations and traditional strength of material concepts the safety factors of stability and stresses are determined. In second method that is named flexible approach, we should prepare a finite element method from the dam, reservoir... 

Wireless Sensor Networks (WSNs) are rapidly emerging as an important area in mobile computing research. Applications of WSNs are numerous and growing, some of them are even highly critical, like military or safety applications. Security measures must be applied to protect the network from a variety of attacks. Since no intrusion prevention measure is perfect, intrusion detection becomes an important second wall to protect the network. WSNs have unique nature which is different from other kinds of networks. In this project, we examine the characteristics and vulnerabilities of WSNs and propose a new intrusion detection model to protect the network security. In this work we have not only... 

With fast improvements of technology in advances in electronic voting systems, has been very effective in substantially reducing the disadvantages of traditional elections and thus enhancing the legitimacy of those being elective. These systems, to be effective,
ought to be designed based on several security factors such as eligibility, correctness, voters' privacy, verifiability and receipt-freeness. One of the most important issues in this concept is ensuring the satisfaction of these properties. Using an incomplete and vulnerable system may cause negative consequences. Therefore, it is necessary to evaluate the system before implementation. Using formal methods for verification of... 

Identification protocols facilitates two participants A and B to identify themselves to each other. Beside identification, A and B can exchange a secret value along with the identification process as the key exchange identification protocol.A secure key exchange identification protocol hould utilize perfect forward secrecy (PFS) property. PFS means if an attacker could compromise an entity in future and gain its long-term key, he cannot succeed to extract previous session keys. So, he will be unable to decrypt previous messages and they will remain secure. Because of the low power and storage of light devices, updating secret shared keys is a solution to reach PFS in such protocols. A major... 

Zero-knowledge proofs are one of the most useful constructions of modern cryptography. Their invention has greatly affected both cryptography and complexity theories. The seemingly paradoxical characteristic of zero-knowledge proofs is that they convince the verifier of the validity of the proposition being proved, yet they yield to further knowledge to him. Two primary applications of zero-knowledge proofs are authentication protocols, as well as sub-protocols which prove that parties involved in some main protocol have acted honestly. In this research, we will survey the models and definitions of zero-knowledge, and analyze their relationship. We then pertain to the interplay between... 

Today, smartphones became a universal technology, and mobile networks speed and bandwidth have increased. Additionally, some of the messengers support voice call services that are easy to use and economical. Many of the VoIP servers provide encrypted VoIP service. On the other side, ISPs need to recognize the VoIP flows to enforce their policies. In some case, ISPs should block illegal VoIP calls or fix a specific charge for them. Also, for providing a better quality of service, it’s necessary to decrease the delay of VoIP packets. Most related works have concentrated on the methods of detecting VoIP traffic that just worked on a specific application. Some other works detect VoIP by using IP... 

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... 

In view of environmental problems and the limited energy supply, synthesis of new liquid fuel from coal or natural gas is becoming a hot research in recent years. Dimethyl ether (DME) is one of the most promising alternates of such synthetic fuels. In this project the kinetics of direct DME synthesis from syngas (H2 and CO) over the new bifunctional catalyst has been investigated in slurry reactor system. A new mechanism and rate law expression were established. The kinetic model has been fitted the experimental data, which has been obtained by other researchers. The new bifunctional catalyst was composed of Cu/ZnO/ZrO2 and Al-modified H-Mordenite zeolite. The calculated apparent... 

Millimeter wave imaging systems have unique features and have been used extensively in a variety of applications including medical imaging, construction operations, places with high security such as airports, Nondestructive testing and etc. These systems provide high resolution, due to the order of wavelength which is several millimeter or centimeter in this band. Also in places with high security and for detecting the concealed objects under people’s clothing, these waves can easily pass through the materials and investigate the person’s body without causing health problems. A wide variety of these imaging systems , each with different design parameters and resolutions, have been proposed.... 

The purpose of this study is developing the design means of a high pressure centrifugal compressor impeller for aviational applications i.e. turboshaft engines. The logic and constraints of designing a high pressure centrifugal impeller for a turboshaft engine is different from those of low pressure aerial or high speed industrial ones. This kind of impeller is deployed in a number of advanced generation of aero engines. In this study, the centrifugal impeller design tools are developed using two design methods. Then, the results are compared, validated and corrected with an existing high pressure impeller data. A number of impellers with pressure ratios ranging from 6 to 11 are designed and... 

Impressive progress in hardwares and developing encryption algorithms in last two decades are caused increase in using encryption protocols in network communications. In last decade, users use privacy preserving networks like Jap and Tor to protect their privacy. These networks protect users' data from eavesdroppers by using three-layer encryption and intermediate nodes between user and target website. Recent researches show that Deep Neural Networks can predict websites viewed by users with high accuracy. In other words, privacy preserving networks suffer from information leakage. In this research, we introduced some of the most powerful methods in encrypted traffic classification and then... 

Electronic processors have encountered Moore’s limitations and they can not meet expectations following computer science advances in new algorithms such as neural networks. These limitations have brought research to focus on light as a high-capacity carrier of information. Light’s degrees of freedom can be exploited whenever the structure has devices able to carry, keep, manipulate and detect each DoF's information but this exploitation may itself lead to either a large footprint or more power consumption. Moreover, there are some scientific and technological difficulties in matching different computational algorithms to these DoF’s requirements. As a result, one must consider all advantages... 

The impressive performance of deep neural networks in various fields has led to the spread of this technology in various organizations and businesses. Training a neural network is a costly process due to the need of collecting relevant data and high computational cost; in this sense, a trained network is considered a valuable asset to any organization. One of the most important attacks against these networks is model extraction attacks. Model extraction attacks are implemented with the aim of training an surrogate model for the target learning model, and in addition to violating the intellectual property of the target model, they can be the basis of other attacks such as an adversarial... 

This study is devoted to the analysis and design of a recently proposed steel-FRP deck system. A methodology is being proposed to analysis the elastic behavior of the proposed deck. In this method the deck is modeled as an equivalent orthotropic plate which is constrained by rotational springs along its edges. An analytical model of the proposed deck is derived by using Rayleigh-Ritz method where the primary Rayleigh-Ritz shape functions are generated from orthonormal polynomials by using Gram-Schmidt procedure. The results of the proposed methodology show good agreement with finite element analysis results. In order to test the applicability of the proposed deck as buildings flooring... 

Quantum mechanics provides a deep understanding of atoms and their interaction with light. As long as we consider only microscopic systems on the scale of an atomic radius, objections to quantum properties such as quantum superposition are nevertheless rare, mainly because of the overwhelming experimental evidence. When it comes to macroscopic systems, many things are not clear anymore. For example,everyday objects of macroscopic size do not exist in superposition of their different states. The reason is that a quantum system interacts with its environment locally,which destroys non-local quantum correlation within the system, larger objects interact with the environment more intensively and... 

This experimental study evaluates the implementation of atmospheric water generator (AWG) apparatus for rural households to supply the needed water. Humid (atmospheric) air is sucked into the condenser and passed through an air filter by a fan; since the temperature of the condenser is lower than the ambient air temperature (dew point temperature), the moist in the atmospheric air is condensed and freshwater is collected which is stored in a tank and after 7 stages of purification will be ready to drink.Data of this project is obtained from Kish Island’s weather station to find the average temperature and humidity. Kish Island is chosen for this project because of its high humidity and...