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functional-design
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Functional Design of a Coating System for the Telescope Mirrors, A Recognition to Telescope of Iranian National Observatory
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Khosroshahi, Habib (Co-Advisor)
Abstract
Functional design of coating system for the primary mirror of the Iranian National Observatory (INO) is done. This telescope has a 3.4 m primary mirror in diameter, made of Zerodur from Schott. Although similar coating systems are in use since years ago, this is the first attempt to design a system for such a large surface case in Iran. Systematic approach led us first to clarify and identifying the design requirements. Lower limit of 80% for reflectance on all wavelength range from 325-1000 nm, thickness of 100 nm with un-uniformity of 5 nm, adhesion enough to pass the selotape test and surface roughness of less than 8 nm. Study of the available methods for coating and selection of the best...
On natural based optimization
, Article Cognitive Computation ; Volume 2, Issue 2 , 2010 , Pages 97-119 ; 18669956 (ISSN) ; Sharif University of Technology
2010
Abstract
Nature has always been a source of great inspiration for engineers and mathematicians. Evolutionary Algorithms are the latest in a line of natural-based innovations which have had a profound effect on the application of optimization in science and engineering. Although based on nature, Evolutionary Algorithms are nonetheless distinctly different from natural evolution in several areas. This paper outlines early and recent developments of Evolutionary Algorithms while covering those areas of difference. Practical issues related to the use of Evolutionary Algorithms, key parameters that affect the quality of the search and impact of user choices in problem formulation are also covered in this...
Fractional/distributed-order systems and irrational transfer functions with monotonic step responses
, Article JVC/Journal of Vibration and Control ; Vol. 20, issue. 11 , 2014 , pp. 1697-1706 ; Sharif University of Technology
Abstract
This paper deals with irrational transfer functions having monotonic nondecreasing step responses. Firstly, some results on the monotonicity of step responses in irrational transfer functions describing fractional- or distributed-order systems are presented. Then, some conditions guaranteeing the existence of monotonic nondecreasing step responses in more general forms of irrational transfer functions are found. Various examples are brought to show the usefulness of the obtained results in time response analysis of fractional/distributed-order systems. The achievements of the paper can be used in the design of control systems having monotonic step responses
Optimal state-feedback design for non-linear feedback-linearisable systems
, Article IET Control Theory and Applications ; Volume 5, Issue 2 , 2011 , Pages 323-333 ; 17518644 (ISSN) ; Farokhi, F ; Karimi-Ghartemani, M ; Sharif University of Technology
2011
Abstract
This paper addresses the problem of optimal state-feedback design for a class of non-linear systems. The method is applicable to all non-linear systems which can be linearised using the method of state-feedback linearisation. The alternative is to use linear optimisation techniques for the linearised equations, but then there is no guarantee that the original non-linear system behaves optimally. The authors use feedback linearisation technique to linearise the system and then design a state feedback for the feedback-linearised system in such a way that it ensures optimal performance of the original non-linear system. The method cannot ensure global optimality of the solution but the global...
Performance analysis of flooding over CSMA in wireless ad-hoc networks
, Article 2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2008, Poznan, 15 September 2008 through 18 September 2008 ; 2008 ; 9781424426447 (ISBN) ; Bahramian, S ; Pakravan, M. R ; Sharif University of Technology
2008
Abstract
Flooding and its variants are the simplest and most widely used broadcasting methods. Therefore, analysis of its performance in an ad-hoc environment using realistic assumptions is an important research topic. In this article, deploying a rigorous theoretic analysis, an upper bound on the performance of probabilistic flooding running over CSMA as a real and suitable MAC layer protocol for broadcasting scenarios is derived in a static multi-hop ad-hoc network in saturated condition. This model reveals the relation between network parameters and the performance of flooding and thus, helps the designer to have a better understanding of the effect of different design parameters. Using this...
A GIS-google earth based approach to estimating the flood damage function in large river basins
, Article World Environmental and Water Resources Congress 2011: Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress, 22 May 2011 through 26 May 2011 ; May , 2011 , Pages 3811-3821 ; 9780784411735 (ISBN) ; Dashti, M ; Alamdari, N ; Salavitabar, A ; Sharif University of Technology
2011
Abstract
Flood as a natural disaster causes heavy human and economic losses and social unrests in most areas of the world. As flood control cost and flood damage compensation is a heavy burden over countries' budget, traditional flood design methods are being replaced by more reliable risk-based methods employing comprehensive risk analysis. In this respect, flood damage estimation is an important step in flood control systems design and analysis. In large river basins with complex reservoir systems and various land uses, flood damage estimation is complex, data-intensive, time demanding, and uncertain task requiring an intensive hydrologic and hydraulic analysis. In this study a simple approach is...
Design of an H∞, PID controller using particle swarm optimization
, Article International Journal of Control, Automation and Systems ; Volume 7, Issue 2 , 2009 , Pages 273-280 ; 15986446 (ISSN) ; Sadati, N ; Ghartemani, M. K ; Sharif University of Technology
2009
Abstract
This paper proposes a novel method to designing an H∞ PID controller with robust stability and disturbance attenuation. This method uses particle swarm optimization algorithm to minimize a cost function subject to-norm to design robust performance PID controller. We propose two cost functions to design of a multiple-input, multiple-output (MIMO) and single-input, single-output (SISO) robust performance PID controller. We apply this method to a SISO flexible-link manipulator and a MIMO super maneuverable F18/HARV fighter aircraft system as two challenging examples to illustrate the design procedure and to verify performance of the proposed PID controller design methodology. It is shown with...