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electronics-engineering
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Enhancement of MAC Protocol of WiGig Network
, M.Sc. Thesis Sharif University of Technology ; Manzuri Shalmani, Mohammad Taghi (Supervisor) ; Ajorloo, Hossein (Co-Advisor)
Abstract
The 60 GHz high speed technology, is the interesting category in network world nowadays. In this study, we consider one of the 60 GHz technologies as it is called WiGig. WiGig works under IEEE802.11ad standard, one of the WLAN standards that works at 60 GHz frequency band. We have surveyed the total MAC and physical layer of this standard to find the way to enhance the MAC protocol. This MAC protocol is applying the CSMA/CA and TDMA methods to access the channel. We have applied the CSMA/CA in our thesis that is a contention based access method. We found that with this method our network is not fair. Since there are not any studies about the value of Fairness in this standard, we...
Application of Software-defined Networking in Enterprise WLAN
, M.Sc. Thesis Sharif University of Technology ; Hemmatyar, Ali Mohamad Afshin (Supervisor)
Abstract
Wireless LANs are becoming widespread in enterprises due to extensive usage of mobile devices and appearance of bring-your-own-device policies. However, mechanisms common in home WLANs are not sufficient for managing lots of access point and clients in an enterprise WLAN and WLAN controllers which are used in enterprises nowadays are limited to a fixed set of commands operated from a CLI and the source code is not changeable. Also, their effectiveness can be harvested alongside access points from the same vendor. Thus, dynamic high level programming for whole network configuration is an absolute need in this changing business environment and Software-defined Networking (SDN) will empower us...
Seismic Design of Substation Structures with Consideration of IEEE-693
, M.Sc. Thesis Sharif University of Technology ; Mofid, Massoud (Supervisor)
Abstract
The Reliability of substation structures with consideration of earthquake uncertainties is one of the most important subjects in structural analysis in recent years. In this project we first introduce IEEE-693-2005, which is the most effective and comprehensive seismic design code for electronic substations. Also in second chapter the rudimentary aspects of Reliability Theory and methods for evaluating the reliability of substation structures is introduced. Then with modeling the most common and most important electronic substation devices in Iran, with consideration of all seismic parameters and their uncertainties, the reliability of these structures evaluated. In this project for...
Expansion of Power Definition in IEEE-1459 in Order to Apply to Shunt Active Power Filters
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
Increase of nonlinear loads has led rise of harmonic currents, voltage distortion and imbalance in power system. Those polluted nonsinusuidal environments have made electrical engineer and researchers to define new and more compelet definition of electrical power quantities such as power factor, apparent power, THD and … . The new definitions have resulted in new methods of power quality enhancement technique. IEEE-1459 Std. proposes definitions for electric power in sinusoidal, nonsinusoidal, balanced and unbalanced conditions which can be used for compensation of nonsinusoidal and unbalanced systems. This reaserch introduces a new method to obtain shunt active filter reference signal. This...
Design and Implementation of a Ultra-Wideband Pulse Interference Immune Communications
, M.Sc. Thesis Sharif University of Technology ; Fotowat-Ahmady, Ali (Supervisor) ; Medi, Ali (Supervisor)
Abstract
One of the serious challenges in Ultra-Wideband (UWB) systems, especially Impulse radio (IR) systems, is the IEEE 802.11a in the middle of the UWB band (In band Interferer) which affects the system performance severely. Matched filter concept shapes the output noise based on its spectrum. For solving the mutual interference between UWB and narrow-band (NB) systems, the unique properties of modified Hermite pulses is utilized to develop a pulse for UWB communications. Matched filter is implemented by designing this pulse featuring notches that can be tuned to a certain frequency. Therefore, NB interferer can be nulled out passing through the matched filter. 0.18 µm CMOS technology has been...
, M.Sc. Thesis Sharif University of Technology ; Mokhtari, Hosain (Supervisor)
Abstract
By taking a new sight into the system dynamic equations, the controllers are designed based on the simplification and converting higher order dynamics to the first order systems. This issue not only simplifies controller design but also stabilize system in all operational points. Moreover, proposed controllers are applied to the parallel Active Power Filters (APFs) because of the new trends in modularizing of APFs. On the other hand, the IEEE-1459 standard has proposed new definitions for the power in unbalanced and non-sinusoidal conditions and it stimulated researchers to use this standard for controlling APF directly. However, the proposed definitions are based on RMS values and...
Throughput Analysis of Routing Algorithms in 802.11s-Based Wireless Mesh Networks
, M.Sc. Thesis Sharif University of Technology ; Ashtiani, Farid (Supervisor)
Abstract
Wireless Mesh Networks (WMNs) can be considered as the result of cooperation among two ad hoc networks, one composed of Mesh Points (MPs) and another one composed of Mesh Clients (MCs) as well as corresponding Access (Mesh) Points. Each one has its own functions and properties. This cooperation results in a flexible network that to fully demonstrate its potentials, requires special routing algorithms and access schemes.Here, we study and analyze three routing algorithms in IEEE 802.11s-based WMNs from throughput point of view. To this end, each node in the network is modeled by a queue during Contention-Free Periods (CFPs). During Contention-Based Period, however, to simplify modeling, we...
Two-dimensional multi-parameter adaptation of noise, linearity, and power consumption in wireless receivers
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Vol. 61, issue. 8 , July , 2014 , p. 2433-2443 ; Sharif Bakhtiar, M ; Sharif University of Technology
Abstract
This paper presents a general method for real-time adaptation of wireless receivers according to the prevailing reception conditions. In order to maintain the desired signal quality at the minimum possible power dissipation, the method performs an optimal trade-off between noise, linearity, and power consumption in the building blocks of the receiver. This is achieved by continuously monitoring the signal-to-noise plus interference ratio (SNIR) and accordingly tuning the adaptation parameters embedded in the receiver design. A prototype DVB-H receiver chip, implemented in a standard 0.18-μ m CMOS process, is used as the test vehicle. By properly trading noise with linearity in the receiver,...
On tuning FO[PI] controllers for FOPDT processes
, Article Electronics Letters ; Volume 49, Issue 21 , 2013 , Pages 1326-1328 ; 00135194 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
2013
Abstract
A method recently proposed for tuning fractional order [proportional integral] (FO[PI]) controllers is investigated. This tuning method, when applied in control of first-order plus dead time (FOPDT) processes, can ensure the desired phase margin, the desired gain crossover frequency and the flatness of the phase Bode plot at such a frequency. The necessary and sufficient condition for the applicability of the aforementioned tuning method is derived. Also, it is shown that this condition can be used in obtaining the achievable performance region of the tuning method in the gain crossover frequency-phase margin plane
Minimal realizations for some classes of fractional order transfer functions
, Article IEEE Journal on Emerging and Selected Topics in Circuits and Systems ; Volume 3, Issue 3 , 2013 , Pages 313-321 ; 21563357 (ISSN) ; Tavakoli Kakhki, M ; Sharif University of Technology
2013
Abstract
It has been known that finding a minimal pseudo state space realization for a fractional order transfer function is helpful in circuitry implementation of such a transfer function with the minimum number of fractional capacitors. Considering this importance, the present paper deals with finding minimal realizations for some classes of fractional order transfer functions. To this end, at first some upper bounds are obtained for the minimal inner dimension of a fractional order transfer function. By considering these upper bounds and also the lower bounds, previously presented in literature, the minimal inner dimension is exactly found for some classes of fractional order transfer functions....
Decomposition of the time delay systems with one delay: The simultaneous similarity of two matrices
, Article ELECO 2013 - 8th International Conference on Electrical and Electronics Engineering, Bursa ; 2013 , Pages 487-491 ; 9786050105049 (ISBN) ; Haeri, M ; Sharif University of Technology
IEEE Computer Society
2013
Abstract
The time delay equations are frequently used to model real systems since they can describe the after-effect phenomenon. It is usually difficult to analyze the properties of time delay systems. Thus it would be beneficial to make the systems as simple as possible. For this purpose, the decomposition of the systems into some separate or cascaded sub-systems with smaller dimension is introduced as the solution of the mentioned complex task. The decomposition of the time delay systems with one delay is directly related to simultaneous similarity of two matrices. In this regard, necessary and sufficient conditions are derived for the existence of a common similar block diagonal or triangular form...
Adaptive leader-following consensus in multi-agent systems with second-order nonlinear dynamics and directed switching topologies
, Article 8th International Conference on Electrical and Electronics Engineering, ELECO 2013, Bursa, 28 November 2013 through 30 November 2013 ; 2013 , Pages 482-486 ; 9786050105049 (ISBN) ; Haeri, M ; Sharif University of Technology
IEEE Computer Society
2013
Abstract
In this paper, we develop control algorithms for addressing second-order consensus problems in intrinsically second-order nonlinear multi-agent dynamical systems with switching topologies. The proposed adaptive controller applies a leader-following strategy in which all agents are assumed to be informed of the leader's state. Another feature of this work which specifically distinguishes it from others is that the proposed controller uses undirected and directed graphs to accommodate for a full range of possible graph information topologies without limitations of bidirectional communication
A high performance real-time simulator for controllers hardware-in-the-loop testing
, Article Energies ; Volume 5, Issue 6 , 2012 , Pages 1713-1733 ; 19961073 (ISSN) ; Karimi, H ; Etemadi, A ; Iravani, R ; Sharif University of Technology
2012
Abstract
This paper presents a high performance real-time simulator for power electronic systems applications and primarily intended for controller hardware-in-the-loop (CHIL) testing. The novelty of the proposed simulator resides in the massively parallel hardware architecture that efficiently exploits fine-grained parallelism without imposing severe communication overhead time that can limit the performance. The simulator enables the use of a nanosecond range simulation timestep to simulate power electronic systems. Through the use of this nanosecond range simulation timestep, the simulator minimizes the error arising from the intersimulation timestep switching phenomenon associated with CHIL. The...
A hybrid genetic algorithm and variable neighborhood search for task scheduling problem in grid environment
, Article Procedia Engineering ; Volume 29 , 2012 , Pages 3808-3814 ; 18777058 (ISSN) ; Khodadadi, F ; Entezari Maleki, R ; Movaghar, A ; Sharif University of Technology
2012
Abstract
This paper addresses scheduling problem of independent tasks in the market-based grid environment. In market-based grids, resource providers can charge users based on the amount of resource requested by them. In this case, scheduling algorithms should consider users' willingness to execute their applications in most economical manner. As a solution to this problem, a hybrid genetic algorithm and variable neighborhood search is presented to reduce overall cost of task executions without noticeable increment in system makespan. Simulation results show that our algorithm performs much better than other algorithms in terms of cost of task executions. Considering the negative correlation between...
Reduced communications fault tolerant task scheduling algorithm for multiprocessor systems
, Article Procedia Engineering ; Volume 29 , 2012 , Pages 3820-3825 ; 18777058 (ISSN) ; Entezari Maleki, R ; Movaghar, A ; Sharif University of Technology
Abstract
Multiprocessor systems have been widely used for the execution of parallel applications. Task scheduling is crucial for the right operation of multiprocessor systems, where the aim is shortening the length of schedules. Fault tolerance is becoming a necessary attribute in multiprocessor systems as the number of processing elements is getting larger. This paper presents a fault tolerant scheduling algorithm for task graph applications in multiprocessor systems. The algorithm is an extension of a previously proposed algorithm with a reduced communications scheme. Simulation results show the efficiency of the proposed algorithm despite its simplicity
Introduction of clinical, simulation-based software for medical sciences teachings
, Article Procedia Engineering ; Volume 29 , 2012 , Pages 43-47 ; 18777058 (ISSN) ; Edalat-Nejad, M ; Edalat Nejad, N ; Edalatnejad, M ; Sharif University of Technology
Abstract
Simulation is the gold standard for training in aviation and trauma medicine. Now it is available for diseases diagnosis and treatment. With simulation, clinicians can practice their art in a realistic, consequence free environment, combining both theory and practice in a comprehensive program. Method and materials - In the virtual clinical environment of "VPsoft mentor" software, the practitioner reviews a patient's history, orders laboratory tests and procedures, interprets findings, renders diagnoses, and prescribes medication. Every diagnostic or treatment decision the clinician makes for the patient is analyzed by E-mentor, providing instant feedback.Results - This software have been...
Cyclic test of steel plate shear wall designed by PFI method
, Article Advanced Materials Research ; Volume 378-379 , 2012 , Pages 785-788 ; 10226680 (ISSN) ; 9783037852880 (ISBN) ; Mofid, M ; Sharif University of Technology
2012
Abstract
In this paper, Plate Frame Interaction (PFI) developed by other researches for modeling Steel Plate Shear Wall (SPSW) is applied for designing a half-scale, single bay and one story SPSW. After designing of SPSW, one specimen is constructed accordingly. In order to determine the mechanical properties of steel, coupon test is performed; and then again theoretical relations based on PFI is re-checked. In this study, gravity loads are neglected and only seismic resistance of SPSW is considered. With cyclic lateral loading as quasi-static load, according to Acceptance Criteria for Cyclic Racking Shear Tests For Metal-Sheathed Shear Walls with Steel Framing (AC154) and obtaining its hysteretic...
Existence of chaos in the fractional order unified system: The lowest effective dimension
, Article ELECO 2011 - 7th International Conference on Electrical and Electronics Engineering, 1 December 2011 through 4 December 2011 ; Dec , 2011 , Pages II396-II399 ; 9786050102048 (ISBN) ; Haeri, M ; Sharif University of Technology
Abstract
This paper deals with the existence of chaos in the fractional order unified system. In an earlier published work, based on the numerical simulation results it is claimed that the lowest effective dimension in the fractional order unified system in order to present chaotic behaviors is 2.76. In this paper, it is analytically shown that the fractional order unified system can be chaotic for effective dimensions lower than the claimed lowest effective dimension. Also, the lowest effective dimension for existence of chaos in such a system is analytically determined. Computer simulation results, obtained based on a reliable numerical method, are brought to back up the presented analytical work...
Composite system well-being analysis using sequential Monte Carlo simulation and fuzzy algorithm
, Article ELECO 2011 - 7th International Conference on Electrical and Electronics Engineering, 1 December 2011 through 4 December 2011, Bursa ; 2011 , Pages I91-I95 ; 9786050102048 (ISBN) ; Fotuhi-Firuzabad, M ; Parvania, M ; Sharif University of Technology
Abstract
Health, Margin and Risk states which in recent years are known as well-being reliability indices, provide a comprehensive adequacy assessment of bulk power system reliability studies. Conventional reliability information about power system operation only considered health and risk states which were not often adequate criteria both in system planning and utilization. It seems margin state as the intermediate condition between health and risk must be considered. Well-being method which is a approach to power system generation adequacy evaluation incorporates deterministic criteria in a probabilistic framework and provides system operating information in addition to risk assessment and can be...
Identification of fractional order model structures using conversion of infinite terms of a response to finite terms
, Article ELECO 2011 - 7th International Conference on Electrical and Electronics Engineering, 1 December 2011 through 4 December 2011 ; December , 2011 , Pages II391-II395 ; 9786050102048 (ISBN) ; Haeri, M ; Sharif University of Technology
2011
Abstract
In this paper, a new method is proposed to determine parameters of some types of fractional order models to represent a system dynamics using its step response. The model structure is assumed to have rational commensurateorder as α = M/N . By this assumption infinite terms of the model step response is converted into finite terms limited to N. The proposed method is practically applicable on all fractional order model structures due to the order approximation imposed by the limited precisions in available computational tools