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electronics-engineering
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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...
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...
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...
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...
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...
, 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...
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 stable platform digital controller based on DSP
, Article ICSES 2008 International Conference on Signals and Electronic Systems, ICSES'08, Krakow, 14 September 2008 through 17 September 2008 ; 2008 , Pages 453-456 ; 9788388309526 (ISBN) ; Chamani Takaldani, H. R ; Moosavienia, A ; Monfaredi, K ; Ebrahimi Atani, R ; Sharif University of Technology
2008
Abstract
The principle, configuration, and the special features of a stable platform digital controller are presented in this paper. The main goal of this paper is replacing an analog controller with its awaiting digital one. This has been done using TMS320LF2402 digital signal processor which offers the enhanced TMS320 DSP architectural design of the C2xx core CPU for low-cost, low-power, and high-performance processing capabilities. The experimental results show that the digital controller is identical to the analog one and can be a suitable replacement for the analog controller. Copyright © 2008 by Department of Electronics, AGH University of Science and Technology
Low power DAC with single capacitor sampling method for SAR ADCs
, Article Electronics Letters ; Volume 52, Issue 14 , 2016 , Pages 1209-1210 ; 00135194 (ISSN) ; Khorami, A ; Sharifkhani, M ; Sharif University of Technology
Institution of Engineering and Technology
2016
Abstract
An ultra-efficient switching method for successive approximation register ADCs is proposed. In this method, the input signals are sampled in a special fashion to reduce the switching energy. Owing to the sampling method, only one reference voltage (Vq=Vref/4) is required to implement the switching steps. Therefore, in addition to reduction in the switching energy (due to the lower supply voltage), the precision of the DAC is improved. The proposed method reduces the switching energy and area by 99.41 and 50%, respectively, compared with the conventional method. © 2016 The Institution of Engineering and Technology
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....
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...
Conditions on polynomials involved in admittance functions passively realizable by using rlc and two fractional elements
, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 67, Issue 6 , 2020 , Pages 999-1003 ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
This brief deals with finding the necessary conditions which should be met by the polynomials appeared in the admittance functions passively realizable by using RLC components and two fractional elements. These conditions include structurally necessary equalities/specifications and positive-realness-based inequalities which should be satisfied by the involved polynomials. In the realizable cases, the acceptable region for choosing the pseudo inductances/capacitances of fractional elements is found from the obtained conditions. © 2004-2012 IEEE
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
Fuzzy trajectory tracking control of an autonomous air vehicle
, Article ICMEE 2010 - 2010 2nd International Conference on Mechanical and Electronics Engineering, Proceedings, 1 August 2010 through 3 August 2010 ; Volume 2 , August , 2010 , Pages V2347-V2352 ; 9781424474806 (ISBN) ; Saghafi, F ; Sharif University of Technology
2010
Abstract
The development and the implementation of a new guidance law are addressed for a six dimensional trajectory tracking problem, three dimensions for position tracking and three dimensions for velocity tracking, of a micro air vehicle. To generate the desired trajectory a virtual leader is defined which is moved in space. In the guidance law, position and velocity feedbacks are used by fuzzy controllers to generate two acceleration commands. Then, a fuzzy coordinator is applied to coordinate the acceleration commands. Nonlinear six-degree-of-freedom equations of motion are used to model the vehicle dynamics. Also, a bank-to-turn acceleration autopilot for vehicle is considered to follow the...
Private Information Retrieval for a Multi-Message Scenario with Private Side Information
, Article IEEE Transactions on Communications ; Volume 69, Issue 5 , 2021 , Pages 3235-3244 ; 00906778 (ISSN) ; Shariatpanahi, S. P ; Maddah Ali, M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
We consider the problem of private information retrieval (PIR), where a single user with private side information (PSI) aims to retrieve multiple files from a library stored at some servers. We assume that the side information (SI) at the user includes a subset of files stored privately. Moreover, the identity of requests and side information at the user are not revealed to any of the servers. The problem involves finding the minimum load transmitted from the servers to the user such that the requested files can be decoded with the help of received data and side information. By providing matching lower and upper bounds for certain regimes, we characterize the minimum load imposed on all the...
RETRACTED ARTICLE: Design, optimization and experimental evaluation of a novel tactile sensor for large surgical grasper
, Article ICMEE 2010 - 2010 2nd International Conference on Mechanical and Electronics Engineering, Proceedings ; Volume 2 , 2010 , Pages V2111-V2116 ; 9781424474806 (ISBN) ; Shamsollahi, M. J ; Mirbagheri, A ; Farahmand, F ; Sharif University of Technology
IEEE Computer Society
2010
Abstract
There has been a rising trend towards robotic tele-surgery operations in recent years. A major concern, however, is the lack of direct contact between the surgeon and patient's body. Several researchers have proposed various designs of tactile sensors for surgical instruments to improve the dexterity of surgeons. Previously designed sensors, however, are mostly suitable for instruments with small contact areas. In this paper, a novel tactile sensor is introduced in integration with the teeth of a surgical grasper for large organs. It includes strain gauges embedded underneath a toothed plate, which also act as grasping teeth of the jaws of the instrument. The thickness of the plate and the...
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...
Efficient DPCM predictor for hardware implementation of lossless medical brain CT image compression
, Article International Conference on Signals and Electronic Systems, ICSES'10 - Conference Proceeding, 7 September 2010 through 10 September 2010 ; September , 2010 , Pages 123-126 ; 9788390474342 (ISBN) ; Mortazavi, M ; Ghorshi, S ; Sharif University of Technology
2010
Abstract
Computed Tomography (CT) medical images show a specific part of human body and present it in a digital form. Lossless image compression is one of the medical imaging applications. To implement such application on hardware we need a simple and fast algorithm. Differential pulse code modulation (DPCM) is a simple and efficient method for transforming image. In this paper best predictor for DPCM introduce in a manner in which has the best result in compression and also be efficient for hardware implementation. After transforming image by DPCM, Huffman encoding used to compress image. We introduce this method with application to brain CT images
On the distortion value of elections with abstention
, Article Journal of Artificial Intelligence Research ; Volume 70 , 2021 , Pages 567-595 ; 10769757 (ISSN) ; Latifian, M ; Ghodsi, M ; Sharif University of Technology
AI Access Foundation
2021
Abstract
In Spatial Voting Theory, distortion is a measure of how good the winner is. It has been proved that no deterministic voting mechanism can guarantee a distortion better than 3, even for simple metrics such as a line. In this study, we wish to answer the following question: How does the distortion value change if we allow less motivated agents to abstain from the election? We consider an election with two candidates and suggest an abstention model, which is a general form of the abstention model proposed by Kirchgässner. Our results characterize the distortion value and provide a rather complete picture of the model. ©2021 AI Access Foundation
Passive realization of fractional-order impedances by a fractional element and rlc components: conditions and procedure
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 64, Issue 3 , 2017 , Pages 585-595 ; 15498328 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
In this paper, conditions for checking the realizability of fractional-order impedance functions by passive networks composed of a fractional element (either a fractional capacitor or a fractional inductor) and some RLC components are derived. To this end, at first the newly obtained conditions for realizability of fractional-order impedance functions by a passive network composed of a fractional capacitor and some RLC components are extended to include the case that the polynomials involving in the impedance function can have roots on the imaginary axis. Then, the necessary and sufficient conditions are found on a fractional-order impedance function to be realized by a passive network...