Sharif Digital Repository

Vulcanization is one the most crucial process in elastomer manufacturing products. It has been shown that network structure and curing kinetic are strongly dependent on curing system formulation. In addition reinforcing fillers in elastomers can affect them as well. By commencement of nanofillers in rubber domain, effects of nanofiller presence on rubber behavior have been investigated by reaserchers.
In this Project the effect of different curing system formulations on vulcanization kinetic and network structure of NR/SBR elastomeric matrice filled by nanodiamond is investigated. Different ingredients and nanodiamond were added to matrix by mechanical mixing in two roll mill. The... 

The aim of this study was to investigate the response of counter flow flames to acoustic excitations numerically. For this purpose, the one-dimensional and two-dimensional laminar counter flow flames are numerically simulated. Cantera is used to simulate the flame in one dimension. In order to consider the counter flow flame as one-dimensional, limiting assumptions are needed, and coding is also required to stimulate the flame acoustically. As a result, a two-dimensional field can be used to simulate a counter flow flame and its acoustic stimulation. This study used Ansys Fluent software to simulate a two-dimensional counterflow flame. Cold solutions without acoustic excitation are first... 

Multimedia applications which exploit the network resources are best provided in broadband networks. Additionally, broadband wireless access systems enable broadband access in places where the wired solutions are not applicable. The IEEE 802.16 standard is designed to provide broadband wireless access and addresses the PHY and MAC layers of wireless metropolitan area networks. This standard has been designed to support quality of service for different applications, and due to their various requirements has considered four classes of service for connections. However, quality of service support mechanisms (such as admission control and packet scheduling), are out of the scope of the standard.... 

Ambient Intelligence (AmI) is an environment in which devices are embedded and connected to each other with a communication network, working in concert to predict users’ wishes according to the context of the environment (devices and people) to help them with their everyday activities. An ambient intelligent environment should be context-aware. One of the most complicated problems in context-aware computations is recognition of the activities in which users of the environment are engaged. These activities could be recognized by means of the information hidden in communication networks of the devices, especially different sensors embedded in the environment to ease up the process. Most of... 

The improvments in computer networks and video compression techniques have motivated the network engineers to broadcast video over the Internet. Recently, Peer-to-Peer networks have been considered as a suitable way for video streaming. P2P networks are distributed and there’s no central management mechanism in them. In addition, video has a time-sensitive nature. Therefore, these networks are vulnerable to security attacks. Denial of Service attacks, attacks on the membership management mechanism, attacks on neighbors selection mechanism, selfish nodes and content pollution attacks are common attack on Peer-to-Peer Video Streaming networks. In a content pollution attack, one or several... 

The IEEE 802.16 is an emerging standard that provides broadband wireless access in metropolitan area networks. The standard facilitates desirable capabilities including mesh topologies and multimedia communications for users.In IEEE 802.16 based mesh networks, there is no explicit uplink and downlink subframes in the physical frame structure and the uplink and downlink traffic scheduling is done within a single time frame. A frame is divided into two subframes: the control subframe and the data subframe. The control subframe is used to carry control messages and the data subframe is used for forwarding data packets to the users.In the mesh mode, two scheduling mechanisms, called centralized... 

Information Technology In the recent years, Peer-to-Peer Networking and Applications has received significant attention from both the Internet users and research area. One of the most successful Applications of P2P networks is streaming the video which is applicable in Internet TV. On the other hand, Complex networks describe a wide range of networked systems in technology, nature and society, such as Internet, WWW networks, P2P networks, biological networks and social interactions.In this thesis we focus on mesh-pull based streaming networks and our goal is to propose a complex network model for such a P2PIPTV topology. To reach to this aim we consider the microscopic processes on each node... 

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... 

Image retrieval, simply put, is the process of finding images in a predefined set , that are similar to an image specified by the user. In particular, the user inputs an image as query, and expects to see images similar to the query. Our purpose is to retrieve the images, by means of visual features, without any use of latent information such as tags and annotations.Afer the first round of retrieval, the answers can become more accurate, by means of user feedbacks. In this state, using active learning methods may be usefull. By using active data selection, we hope to achieve the answer faster. Learning based on manifold assumption, is another means which may be used in image retrieval.... 

Many real-world communication systems such as Internet, online social networks, and brain networks can be modeled as a complex network of interacting dynamical nodes. These networks have non-trivial topological features, i.e., features that do not occur in simple networks such as lattices or random networks. The tremendous growth of Internet and its applications in recent years has resulted in creation of large-scale complex networks involving tens or hundreds of millions of nodes and links. Thus, it may be impossible or costly to obtain a complete picture of these large networks, and sampling methods are essential for practical estimation of network properties. Therefore, in this thesis, we... 

Over the past few years, various studies have demonstrated that the complex networks can be used to model the structure and functions of human brain. Some of these studies indi- cated that diseases such as Alzheimer, Epilepsy, and Schizophrenia can cause changes in this network. The main idea behind the methods proposed to analyze human brain’s behav- ior, is to identify regions of the brain with specific tasks. Recent studies show that multiple regions of human brain are involved in complex activities, so it’s important to detect their interactions. Using functional high resolution multichannel neurophysiological signals, like electroencephalographic (EEG) and magnetoencephalographic... 

Nowadays, many entities and the relationships between them create different types of networks. Graphs are appropriate tools to model these networks. In a graph, nodes show individuals and edges show the relations between them. One of the most important research problems in the field of network analysis is community detection. In a network, a community is a group of nodes that has a lot of connections to the nodes inside the same group and a few to the ones which are outside. Community detection has many real world applications. Recommending items in recommender systems, detecting spy and terrorist groups and predicting future links between members in a social network are some examples where...