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Temporal dynamics of connectivity and epidemic properties of growing networks
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 93, Issue 1 , 2016 ; 15393755 (ISSN) ; Khani Shirkoohi, M ; Sharif University of Technology
American Physical Society
2016
Abstract
Traditional mathematical models of epidemic disease had for decades conventionally considered static structure for contacts. Recently, an upsurge of theoretical inquiry has strived towards rendering the models more realistic by incorporating the temporal aspects of networks of contacts, societal and online, that are of interest in the study of epidemics (and other similar diffusion processes). However, temporal dynamics have predominantly focused on link fluctuations and nodal activities, and less attention has been paid to the growth of the underlying network. Many real networks grow: Online networks are evidently in constant growth, and societal networks can grow due to migration flux and...
Extracting Cascaded Information Networks FromSocial Networks
,
M.Sc. Thesis
Sharif University of Technology
;
Rabiei, Hamid Reza
(Supervisor)
Abstract
The diffusion process propagates information, viruses, ideas, innovations and new be-haviours over social networks. Adopting a new behaviour, which is mentioned as an in-fection, starts from a little group of people. Spreading it over more neighbors and friendscan result in an epidemic phenomenon over the network. As this infection propagates, aninformation cascade will be generated. The spread of information cascades over social net-works forms the diffusion networks. Although observing the infection time of a person ispossible, determining the source of infection is usually a difficult problem. Additionally, inmany applications we can not observe the underlying network which diffusion...
DNE: A method for extracting cascaded diffusion networks from social networks
, Article Proceedings - 2011 IEEE International Conference on Privacy, Security, Risk and Trust and IEEE International Conference on Social Computing, PASSAT/SocialCom 2011, 9 October 2011 through 11 October 2011 ; October , 2011 , Pages 41-48 ; 9780769545783 (ISBN) ; Rabiee, H. R ; Salehi, M ; Sharif University of Technology
2011
Abstract
The spread of information cascades over social networks forms the diffusion networks. The latent structure of diffusion networks makes the problem of extracting diffusion links difficult. As observing the sources of information is not usually possible, the only available prior knowledge is the infection times of individuals. We confront these challenges by proposing a new method called DNE to extract the diffusion networks by using the time-series data. We model the diffusion process on information networks as a Markov random walk process and develop an algorithm to discover the most probable diffusion links. We validate our model on both synthetic and real data and show the low dependency...
Inferring dynamic diffusion networks in online media
, Article ACM Transactions on Knowledge Discovery from Data ; Volume 10, Issue 4 , 2016 ; 15564681 (ISSN) ; Hemmatyar, A. M. A ; Rabiee, H. R ; Ramezani, M ; Sharif University of Technology
Association for Computing Machinery
Abstract
Online media play an important role in information societies by providing a convenient infrastructure for different processes. Information diffusion that is a fundamental process taking place on social and information networks has been investigated in many studies. Research on information diffusion in these networks faces two main challenges: (1) In most cases, diffusion takes place on an underlying network, which is latent and its structure is unknown. (2) This latent network is not fixed and changes over time. In this article, we investigate the diffusion network extraction (DNE) problem when the underlying network is dynamic and latent. We model the diffusion behavior (existence...
A topology-aware load balancing algorithm for P2P systems
, Article 4th International Conference on Digital Information Management, ICDIM 200916 December 2009 ; 2009 , Pages 97-102 ; 9781424442539 (ISBN) ; Shahparian, J ; Ghodsi, M ; Sharif University of Technology
Abstract
One of the challenges of P2P systems is to perform load balancing efficiently. A distributed hash table (DHT) abstraction, heterogeneous nodes, and non uniform distribution of objects cause load imbalance in structured P2P overlay networks. Several solutions are suggested to solve this problem but they have some restrictions. They assume the homogeneous capabilities of nodes, unawareness of the link latency during transferring load and imposing logical structures to collect and reassign load. This paper presents a distributed load balancing algorithm with topology awareness using the concept of virtual servers. In our proposed approach, each node collects neighborhood load information from...
DCS: A distributed coordinate system for network positioning
, Article Proceedings - IEEE International Symposium on Distributed Simulation and Real-Time Applications, DS-RT, 25 October 2009 through 28 October 2009, Singapore ; 2009 , Pages 113-120 ; 15506525 (ISSN) ; 9780769538686 (ISBN) ; Habibi, J ; Shirmohammadi, S ; Hariri, B ; Sharif University of Technology
Abstract
Predicting latency between nodes on the internet can have a significant impact on the performance of many services that use latency distances among nodes as a decision making input. Coordinate-based approaches are among the family of latency prediction techniques where latency between each pair of nodes is modeled as the virtual distance among those nodes over a virtual system. This article proposes the Decentralized Coordinate System (DCS) as a fully distributed system that does not rely on any infrastructure support from the underlying network. DCS uses a two-phase algorithm: first, each host is assigned rough coordinates, then, the rough estimation is refined in a way that it gradually...
Tree optimization in overlay multicast based on location and bandwidth
, Article ICCTD 2009 - 2009 International Conference on Computer Technology and Development, 13 November 2009 through 15 November 2009 ; Volume 2 , 2009 , Pages 46-49 ; 9780769538921 (ISBN) ; Movaghar, A ; Sharif University of Technology
Abstract
One of the main parts of peer-to-peer multicast is the structure of overlay network. Most of the existing works utilize some common parameters for constructing overlay tree. These parameters are bandwidth and delay. The mismatch between current overlay structure and underlying network topology causes severe link stress and then leads to high end to end latency. According to these problems, we propose a new overlay construction algorithm called OLT in this paper that finds the location of peers and tries to connect peers that are as close as possible. OLT exploits a number of heuristic techniques to reach an optimized tree even in case of peer heterogeneity and high churn rate. Our...
Performance comparison of simple regular meshes and their k-ary n-cube variants in optical networks
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 543-550 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Dadlani, A ; Rajabi, A ; Aghajani, M. R ; Khonsari, A ; Seyed Razi, H ; Sharif University of Technology
2008
Abstract
The need for supporting the ever-growing number of multi-computers in the contemporary Internet has persuaded researches worldwide to search for suitable underlying network topologies with desirable properties. Even in the presence of speedy optical technologies, the arrangement of nodes in a network can be highly influential. Among all the topologies investigated so far, k -ary n-cubes have been reported to be widely adopted in the literature. But in hybrid networks, where the network is composed of a mixture of different types of topologies, the type and size of k-ary n-cubes can greatly affect the performance factor of the network. In this paper, we study and compare the performance...
Topological pattern selection in recurrent networks
, Article Neural Networks ; Volume 31 , 2012 , Pages 22-32 ; 08936080 (ISSN) ; Abbassian, A ; Sharif University of Technology
2012
Abstract
The impact of adding correlation to a population of neurons on the information and the activity of the population is one of the fundamental questions in recent system neuroscience. In this paper, we would like to introduce topology-based correlation at the level of storing patterns in a recurrent network. We then study the effects of topological patterns on the activity and memory capacity of the network. The general aim of the present work is to show how the repertoire of possible stored patterns is determined by the underlying network topology.Two topological probability rules for pattern selection in recurrent network are introduced. The first one selects patterns according to a...