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asavdi--sepehr
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Analysis of Age of Information in Multisource Communication Networks
, M.Sc. Thesis Sharif University of Technology ; Ashtiani, Farid (Supervisor)
Abstract
In this thesis, we investigate the age of information in multisource networks. To this end, in the first phase of this thesis, we evaluate the Age of Information (AoI) in slotted ALOHA network. Regarding the interactions among the nodes in such a network, we model the memory of this network with a Trellis and find the peak Age of Information (PAoI) by using this Trellis. Then, we evaluate Age of Information-constrained regions and achievable throughput regions in the slotted ALOHA network and optimize Age of information in a symmetric case. In the second phase, we propose an efficient prioritizing scheme from AoI point of view and find the distribution of AoI and PAoI in such a scheme with...
Multi-cass Semi-srvised Classification of Data Streams
, M.Sc. Thesis Sharif University of Technology ; Beigy, Hamid (Supervisor)
Abstract
Recent advances in storage and processing have provided the ability of automatic gathering of information which in turn leads to fast and contineous flow of data. The data which are produced and stored in this way are named data streams. It has many applications such as processing financial transactions, the recorded data of various sensors or the collected data by web sevices. Data streams are produced with high speed, large size and much dynamism and have some unique properties which make them applicable in precise modeling of many real data mining applications. The main challenge of data streams is the occurrence of concept drift which can be in four types: sudden, gradual, incremental or...
Fault-tolerant Attitude Control of Sattelite Using Neural Networks
, M.Sc. Thesis Sharif University of Technology ; Asadian, Nima (Supervisor)
Abstract
This research aims to introduce a new integrated fault tolerant attitude control system of satellites based on the neural networks. First, a linear controller and an optimal controller are designed assuming that no fault occurs in the reaction wheels of the satellite. It is obvious that these controllers are not able to respond properly when a fault occurs. Therefore, artificial neural networks are employed in the fault tolerant controller design. Neural networks are well-known for their adaptiveness and the ability to learn the dynamics of a system. Therefore, they can be used to predict the faulty conditions. In this research two approaches are examined to deal with the faulty conditions....
Viral cascade probability estimation and maximization in diffusion networks
, Article IEEE Transactions on Knowledge and Data Engineering ; 28 May , 2018 ; 10414347 (ISSN) ; Beigy, H ; Sharif University of Technology
IEEE Computer Society
2018
Abstract
People use social networks to share millions of stories every day, but these stories rarely become viral. Can we estimate the probability that a story becomes a viral cascade If so, can we find a set of users that are more likely to trigger viral cascades These estimation and maximization problems are very challenging since both rare-event nature of viral cascades and efficiency requirement should be considered. Unfortunately, this problem still remains largely unexplored to date. In this paper, given temporal dynamics of a network, we first develop an efficient viral cascade probability estimation method, VICE, that leverages an special importance sampling approximation to achieve high...
Viral cascade probability estimation and maximization in diffusion networks
, Article IEEE Transactions on Knowledge and Data Engineering ; Volume 31, Issue 3 , 2019 , Pages 589-600 ; 10414347 (ISSN) ; Beigy, H ; Sharif University of Technology
IEEE Computer Society
2019
Abstract
People use social networks to share millions of stories every day, but these stories rarely become viral. Can we estimate the probability that a story becomes a viral cascade? If so, can we find a set of users that are more likely to trigger viral cascades? These estimation and maximization problems are very challenging since both rare-event nature of viral cascades and efficiency requirement should be considered. Unfortunately, this problem still remains largely unexplored to date. In this paper, given temporal dynamics of a network, we first develop an efficient viral cascade probability estimation method, ViCE, that leverages an special importance sampling approximation to achieve high...
Structural virality estimation and maximization in diffusion networks
, Article Expert Systems with Applications ; Volume 206 , 2022 ; 09574174 (ISSN) ; Beigy, H ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Social media usage is one of the most popular online activities and people shares millions of message in a short time; however this information rarely goes viral. The diffusion process begins with an initial set of source nodes and continues with other nodes. In addition, the viral cascade is triggered when the number of infected nodes exceeds a specific threshold. Then, we find an initial set of source nodes that maximizes the number of infected nodes given the source nodes. This study aims to answer the following questions: how does a spread like a viral cascade propagate in a network? Do the structural properties of the propagation pattern play an important role in virality? If so, can we...
Information and Influence Diffusion in Social Network
,
Ph.D. Dissertation
Sharif University of Technology
;
Beigy, Hamid
(Supervisor)
Abstract
People use social networks to share millions of stories every day, but these stories rarely become viral. Can we estimate the probability that a story becomes a u/rof cascade? If so, can we find a set of users that are more likely to trigger viral cascades? There are many factors influenced the message virality. In this thesis, we investigate the effect of graph structure, diffusion pattern as well as the message text on virality measure. Finally, the authors solve both source localization and inferring COVID-19 network via propsed methods.First, the authors investigate probability estimation and maximization of cascade virality. In this section, we develop an efficient viral cascade...
An analytical model for evaluation of wireless mesh networks
, Article 2008 International Symposium on Telecommunications, IST 2008, Tehran, 27 August 2008 through 28 August 2008 ; October , 2008 , Pages 295-300 ; 9781424427512 (ISBN) ; Ashtiani, F ; Sharif University of Technology
2008
Abstract
Wireless mesh networks (WMNs) are well-promising future networks especially for ubiquitous connection to Internet. In this paper, we propose an analytical model in order to evaluate the maximum stable throughput of a WMN based on a simplified version of IEEE 802.11s MAC protocol. Our modeling approach is based on a multi-class open queueing network. In this respect, we map some of the important features of IEEE 802.11s MAC protocol, esp., its contention-based and contention-free periods onto different parameters of the proposed queueing network. By solving the related traffic equations and applying the stability condition, we determine the maximum stable throughput, i.e., the maximum packet...
Three-phase Model for a Fixed-bed Laboratory Scale Diesel Hydrotreating Reactor
, M.Sc. Thesis Sharif University of Technology ; Khorasheh, Fahad (Supervisor) ; Sadighi, Sepehr (Supervisor)
Abstract
The harmful environmental effects of gases resulting from the combustion of sulfur compounds in fuel, poisoning of catalysts, corrosion of equipment, as well as the intensification of environmental considerations and new standards adopted for the maximum amount of sulfur, have made the desulfurization of fuels important; Meanwhile, the desulfurization method using hydrogen has a high potential to remove sulfur compounds. For example, diesel fuel contains a variety of impurities such as sulfur, nitrogen (basic and Non-basic), and aromatic compounds, the sulfur in diesel fuel causes many problems related to environmental pollution and corrosion of engine components. Also, due to the high...
Study the Interaction between Cytoskleton and Cell Membrane
, M.Sc. Thesis Sharif University of Technology ; Nejat Pishkenari, Hossein (Supervisor) ; Salarieh, Hassasn (Supervisor)
Abstract
In this project the main aim is to model the interaction between the cytoskeleton and cell membrane. In order to model the membrane and cytoskeleton it is used a discrete model, which contains several beads. For modeling the interaction between the beads it is used different kinds of energies. It is used four potentials in a 2D model for modeling the interaction between the membrane beads and it is used SSLJ potential in order to model the interaction between the cytoskeleton and cell membrane. Furthermore, this potential is used to model the interaction between the cytoskeleton filaments. Due to this potential, the cytoskeleton filaments can cross each other in the 2D model. For modeling...