Karimzadeh R.,Tarbiat Modares University |
Karimzadeh R.,Research Institute for ICT ITRC |
Hakkak M.,Tarbiat Modares University |
Haddadi A.,Amirkabir University of Technology |
Forooraghi K.,Tarbiat Modares University
IET Microwaves, Antennas and Propagation | Year: 2012
This article generalises a pattern synthesis technique to conformal arrays. An iterative method is used for optimisation of element excitations in an array of rectangular patch elements that are conformed to a hemispheric surface. The embedded-element co-polarisation and cross-polarisation patterns are evaluated using a full-wave method. These patterns are used in a newly introduced iterative synthesis algorithm to obtain the minimum sidelobe level (SLL) and cross-polarisation level (XPL). The mutual coupling effects on the synthesis results are investigated in this procedure. The synthesised patterns show adequate XPL and SLL comprised to other methods. The weighted alternating reverse projection (WARP) method is modified and it is shown that the WARP method can synthesise lower XPL and SLL than those of other methods. Compared with other synthesis method, the WARP improves SLL by 2 dB and XPL by about 1.5 dB in 19 element array. © 2012 The Institution of Engineering and Technology.
Mahmoudi M.T.,University of Tehran |
Mahmoudi M.T.,Research Institute for ICT ITRC |
Parsanasab M.,University of Tehran |
Khadem Haghighat M.,University of Tehran |
And 2 more authors.
Proceedings - 2012 6th IEEE International Conference on E-Learning in Industrial Electronics, ICELIE 2012 | Year: 2012
With the rapid emergence of semantic schema on web, storing, querying, indexing, and retrieving XML data have become critical issue in various processes on educational documents specially in e-learning environments. In this paper, a framework for web service-based design of semantic schema for education- supportive documents is represented. The whole process is made up of two major parts of designing service-based infrastructure and providing automatic semantic schema through a converter which is designed for this purpose. Experimental results on about 164 education-supportive documents lead us to estimate that our framework is capable of web service-based design of semantic schema in about 87 percent of the situations. Since we have considered web services which are disjointed from the constituents of the whole system, the proposed framework is software/ hardware independent and can be applied to any other document-based e-learning applications. © 2012 IEEE.
Tayefeh Mahmoudi M.,University of Tehran |
Tayefeh Mahmoudi M.,Research Institute for ICT ITRC |
Taghiyareh F.,University of Tehran |
Forouzideh N.,University of Tehran |
Lucas C.,University of Tehran
Neural Computing and Applications | Year: 2013
Evolving artificial neural network usually refers to network structure evolution leaving the network's parameters to be trained using conventional algorithms. In this paper, we present a new method for artificial neural network evolution that evolves the network structure along with the network parameters. The proposed method uses grammatical encoding together with colonial competitive algorithm to evolve artificial neural network structure and parameters. This allows for a better description of the network using a formal grammar allowing the network architecture to shape the resulting search space in order to meet each problem requirement. The proposed method is compared with other five methods for artificial neural network training and is evaluated using four known regression problems. In all four datasets, the proposed method outperforms its competitors. © 2012 Springer-Verlag London Limited.
Goudarzi P.,Research Institute for ICT ITRC
Wireless Networks | Year: 2013
Non-cooperative game theory has found many important applications in engineering. In networking research community, this theory has been adopted to represent the selfish behaviour of the network users. In video transmission over Mobile Ad hoc NETworks (MANETs), video sources try to optimize their perceived video quality unilaterally. On the other hand, network providers try to set some prices on the scarce network resources such that their associated income is maximized. In the current paper, a non-cooperative quality game framework has been introduced in which by exploiting a related quality metric, scalable video users try to optimize their perceived quality in a distributed manner. The existence of a Nash Equilibrium (NE) has been proved and the stability of the distributed resource allocation strategy has been investigated. In the proposed resource assignment game, the utility functions of all competing scalable video sources converge to some optimal value which is dictated by the resulting Nash equilibrium in the allocated rates. In this optimal point, no player (video source) can enhance its utility unilaterally without compromising other players' utility. The assigned rates in the game can be considered as rate-feedbacks for on-line rate adaptation of a moderate scalable video encoder such as H.264/MPEG4 AVC. Some numerical analysis have been presented to validate the theoretical results and to verify the claims. © 2012 Springer Science+Business Media, LLC.
Goudarzi P.,Research Institute for ICT ITRC
International Journal of Multimedia and Ubiquitous Engineering | Year: 2012
From the viewpoint of service operators the Total Cost of Ownership (TCO) for developing a communication service comprises from two parts; CAPital EXpenditure (CAPEX) and OPerational EXpenditure (OPEX). These two types of costs are interrelated and affect any service provider's deployment strategy. In many traditional methods, selection of critical elements of a new service is performed in a heuristic manner aimed at reducing only the OPEX part of the TCO which is not necessarily optimal. Furthermore, exact cost modeling for such services is not always possible and contains some uncertainties. In the current work, after cost modeling of each video streaming element by capturing the effect of the model uncertainties, the TCO optimization problem for video streaming over IP networks is formulated as a stochastic optimization problem. The solution of the proposed optimization problem can cope with the cost modeling uncertainties and track the dynamism in the TCO and lead to a time-varying optimal solution. Numerical analysis results verify the developed method.
Badie K.,Research Institute for ICT ITRC |
Tayefeh Mahmoudi M.,Research Institute for ICT ITRC
Communications in Computer and Information Science | Year: 2011
In today's competitive world for companies and institutions, providing correct and instant information using the global internet network for successful managers is critical. Considering the high importance of websites in various economic, educational, social, cultural and political areas, senior managers of companies or institutions are willing to monitor their content personally. On the other hand, attracting and retaining the user or customer is also important. One of the systems that can save resources and, because of its dynamic features, is user-friendly and can attract and maintain users, is content management system (CMS) which- using a simple, dynamic and professional environment- provides facilities to users and administrators enabling them to easily manage their website. In this paper, after studying and comparing some of these systems and their crucial factors, strengths and weaknesses, we use email questionnaires to collect CMS users' opinions on some components of CMS. Next, we discuss the proposed structure and the software factors which must be considered in the design and construction of these systems. © 2011 Springer-Verlag.