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Power system stabilizer tuning using wide area control signals
, Article 2008 IEEE Electrical Power and Energy Conference - Energy Innovation, Vancouver, BC, 6 October 2008 through 7 October 2008 ; 2008 ; 9781424428953 (ISBN) ; Ranjbar, A. M ; Nourizadeh, S ; Sharif University of Technology
2008
Abstract
Abstract- Benefits of PSS application for electromechanical oscillations damping is clarified. A major difficulty of PSS application is its tuning such that its damping characteristics do not fall into overcompensation facing continuously changing power systems. This paper presents an approach for wide area monitoring and control based PSS tuning. The presented approach originated from adaptive tuning based on real time power system state estimation. © 2008 IEEE
Transmission capability improvement using wide area monitoring and control
, Article 2008 IEEE Electrical Power and Energy Conference - Energy Innovation, Vancouver, BC, 6 October 2008 through 7 October 2008 ; January , 2008 ; 9781424428953 (ISBN) ; Ranjbar, A. M ; Nourizadeh, S ; Sharif University of Technology
2008
Abstract
Operation of transmission lines are usually limited by stability limits rather than thermal capacity limits. Thermal limit of transmission lines is a physical limitation of their components and not related with the overall power system characteristics, but stability limits are strictly related with power system characteristics. This paper presents an approach for increasing stability limits using PSS. © 2008 IEEE
Power system restoration planning based on Wide Area Measurement System
, Article International Journal of Electrical Power and Energy Systems ; Volume 43, Issue 1 , 2012 , Pages 526-530 ; 01420615 (ISSN) ; Nezam Sarmadi, S. A ; Karimi, M. J ; Ranjbar, A. M ; Sharif University of Technology
2012
Abstract
This paper presents a method for the optimal restoration planning based on Wide Area Measurement System (WAMS). This method uses observability analysis and Power Transfer Distribution Factor (PTDF) concept. The PTDF concept is applied to decrease the overvoltages caused by energizing transmission lines with lightly load. The New England 39 bus power system is used to demonstrate the proposed algorithm and verify the results. The outcomes of the study are evaluated to show the validity and reliability of the presented approach
Frequency monitoring and control during power system restoration based on wide area measurement system
, Article Mathematical Problems in Engineering ; Volume 2011 , 2011 ; 1024123X (ISSN) ; Yari, V ; Ranjbar, A. M ; Sharif University of Technology
2011
Abstract
Frequency control during power system restoration has not been strongly addressed. Operators are often concerned with the offline sizing of load and generation steps, but, nowadays, the introduction of Wide Area Measurement System (WAMS) makes it possible to monitor the stability of power system online. The constraints of WAMS operation result in some changes in power system frequency control. This paper proposes a novel methodology for frequency control and monitoring during the early steps of power system restoration based on WAMS. Detailed load modeling is achieved based on the static load modeling approach. Power generators' modeling is also accomplished utilizing the single machine...
Load pickup during power system restoration
, Article Series on Energy and Power Systems, 6 September 2010 through 8 September 2010, Gaborone ; 2010 , Pages 161-164 ; 14827891 (ISSN) ; 9780889868755 (ISBN) ; Yari, V ; Ranjbar, A. M ; Sharif University of Technology
2010
Abstract
The first control action in power system restoration concerns the generation restart. In the initial phase of restoration, operators are often concerned with load pickup problems. One of the important problems during load pickup is keeping frequency response in allowable range. The aim of this paper is to determine the best sequence of load pickup by hydro and steam units during power system restoration based on frequency response of prime movers. Hydro power plants and combustion turbine units have the capability of black start operation and can be used for early stages of power system restoration. This paper considers hydro power plants for evaluating the stability and frequency response...
Power System Restoration Using Wide Area Measurement System (WAMS)
, Ph.D. Dissertation Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
The introduction of Wide Area Measurement Systems (WAMS) made it possible to monitor the stability online. This thesis presents a method for the optimal restoration planning based on Wide Area Measurement System (WAMS). In fact, the practical use of WAMS at the early stages of restoration provides precise determination of generators loading steps. Moreover, unification of phase angle references at different islands and presentation of tie line energizing priority list are significant benefits of WAMS at the last stages of restoration. The presented method uses observability analysis and Power Transfer Distribution Factor (PTDF) concept. The PTDF concept is applied to decrease the...
Power system stability assessment during restoration based on a wide area measurement system
, Article IET Generation, Transmission and Distribution ; Volume 6, Issue 11 , 2012 , Pages 1171-1179 ; 17518687 (ISSN) ; Karimi, M. J ; Ranjbar, A. M ; Shirani, A ; Sharif University of Technology
2012
Abstract
Online power system stability assessment during restoration has not been strongly addressed yet. The introduction of wide area measurement systems (WAMS), however, made it possible to monitor the stability online. This study technically presents a detailed analysis of stability during restoration using WAMS. The power system build-up strategy is used as the restoration approach, based on which the early and the last stages of restoration are to divide the power system into islands and interconnect them, respectively. In fact, the practical use of WAMS at the early stages of restoration provides precise determination of generators loading steps. Moreover, unification of phase angle references...
Standing phase angle reduction based on a wide area monitoring system using genetic algorithm
, Article International Journal of Emerging Electric Power Systems ; Volume 11, Issue 3 , Jul , 2010 ; 1553779X (ISSN) ; Ranjbar, A. M ; Pishvaie, M. R ; Sadeghi, M ; Sharif University of Technology
2010
Abstract
During power system restoration, it is necessary to check the phase angle between two buses before closing circuit breakers to connect a line between them. A novel approach for reducing large standing phase angle (SPA) based on Genetic Algorithm (GA) is presented in this paper. The proposed approach starts with a state estimation on Wide Area Monitoring System (WAMS) data measurements and considering power system operation and angular stability constraints, seeks an optimal control action scenario for reducing SPA. Since these constraints are evaluated based on WAMS data, the presented approach is considerably high speed and accurate. As an optimization problem, objective function of the...
Photoluminescent carbon quantum dot/poly-L-Lysine core-shell nanoparticles: A novel candidate for gene delivery
, Article Journal of Drug Delivery Science and Technology ; 2020 ; Mofazzal Jahromi, M. A ; Abdoli, A ; Mohammad Beigi, H ; Fatahi, Y ; Nourizadeh, H ; Zare, H ; Kiani, J ; Radmanesh, F ; Rabiee, N ; Jahani, M ; Mombeiny, R ; Karimi, M ; Sharif University of Technology
Editions de Sante
2020
Abstract
Cationic polymers such as poly-L-lysine (PLL) are able to interact electrostatically with DNA to produce polymeric systems with nanometric diameters due to the neutralization and accumulation of DNA. This study integrates the outstanding properties of carbon quantum dots (CQDs) with PLL to develop a novel gene delivery vehicle with a core-shell hybrid nanostructure. The CQD/PLL core-shell nanoparticles (NPs) were, therefore, synthesized in such a way that they had narrow size distribution and an average diameter under 10 nm, both of which were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy exhibited that...
Photoluminescent carbon quantum dot/poly-L-Lysine core-shell nanoparticles: A novel candidate for gene delivery
, Article Journal of Drug Delivery Science and Technology ; Volume 61 , 2021 ; 17732247 (ISSN) ; Mofazzal Jahromi, M. A ; Abdoli, A ; Mohammad Beigi, H ; Fatahi, Y ; Nourizadeh, H ; Zare, H ; Kiani, J ; Radmanesh, F ; Rabiee, N ; Jahani, M ; Mombeiny, R ; Karimi, M ; Sharif University of Technology
Editions de Sante
2021
Abstract
Cationic polymers such as poly-L-lysine (PLL) are able to interact electrostatically with DNA to produce polymeric systems with nanometric diameters due to the neutralization and accumulation of DNA. This study integrates the outstanding properties of carbon quantum dots (CQDs) with PLL to develop a novel gene delivery vehicle with a core-shell hybrid nanostructure. The CQD/PLL core-shell nanoparticles (NPs) were, therefore, synthesized in such a way that they had narrow size distribution and an average diameter under 10 nm, both of which were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy exhibited that...
The relationship between an EFL teacher's gender and students' willingness to communicate
, Article International Journal of Communication and Linguistic Studies ; Volume 10, Issue 4 , 2013 , Pages 17-29 ; 23277882 (ISSN) ; Pakzadian, S. S
Common Ground Publishing
2013
Abstract
Learning a foreign language encompasses a process of trial and error that can lead to the progression of the learner's interlanguage, meaning that the learners make use of their language knowledge that receives feedback and brings about progress through diagnosis of the problems and being corrected by the teacher. Therefore, there exists a need to analyze the underlying reasons causing the students to remain taciturn with a low willingness to communicate (WTC) during a language class. There has been much work done investigating the role of the learner's stable personal characteristics (traits) along with their situational changes at a specific time (states) that influence the student's...
Discrimination of heart arrhythmias using novel features in heart rate phase space
, Article Computing in Cardiology ; Volume 40 , Sept , 2013 , Pages 1035-1038 ; 23258861 (ISSN); 9781479908844 (ISBN) ; Rezaei, S ; Salavatian, S
2013
Abstract
In this paper, we try to recognize and distinguish different groups of arrhythmia using novel features which have been obtained from the heart rate's phase space in recent years. For this purpose, we used Triangular Phase Space Mapping (TPSM) and Parabolic Phase Space Mapping (PPSM). For recognition, we used three groups of 15 subjects using the Physionet database (Arrhythmia, Congestive Heart Failure (CHF), and Atrial Fibrillation (AF)) with Normal Sinus Rhythm (NSR). The obtained features discriminate arrhythmia from NSR by p
An automated simple algorithm for realistic pore network extraction from micro-tomography images
, Article Journal of Petroleum Science and Engineering ; Vol. 123, issue , 2014 , pp. 164-171 ; ISSN: 09204105 ; Jamshidi, S ; Salehi, S
2014
Abstract
Using 3-D scanned data to analyze and extract pore network plays a vital role in investigation of porous media's characteristics. In this paper, a new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network. This automated method utilizes some of the common and well-known image processing functions which are widely accessible by researchers and this has led to an easy algorithm implementation. In this method, after polishing and quality control of images, using city-block distance function and watershed segmentation algorithm, pores and throats are detected and 3-D network is produced. This method can also be applied on 2-D images...
An intelligent hybrid classification algorithm integrating fuzzy rule-based extraction and harmony search optimization: Medical diagnosis applications
, Article Knowledge-Based Systems ; Volume 220 , 2021 ; 09507051 (ISSN) ; Abdullah, S ; Akhavan Niaki, S. T ; Banihashemi, S ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Uncertainty is a critical factor in medical datasets needed to be overcome for increasing diagnosis efficiency. This paper proposes an intelligent classification algorithm comprising a fuzzy rule-based approach, a harmony search (HS) algorithm, and a heuristic algorithm to classify medical datasets intelligently. Two fuzzy approaches, as well as orthogonal and triangular fuzzy sets, are first utilized to define the attributes of data. Then, an HS algorithm is integrated with a heuristic to generate fuzzy rules to select the best rules in the fuzzy rule-based systems. Moreover, to improve the performance of the proposed classification approach, a three-phase parameter tuning approach is...
Performance evaluation of shared hosting security methods
, Article Proc. of the 11th IEEE Int. Conference on Trust, Security and Privacy in Computing and Communications, TrustCom-2012 - 11th IEEE Int. Conference on Ubiquitous Computing and Communications ; 2012 , Pages 1310-1315 ; 9780769547459 (ISBN) ; Arshad, S ; Khoshkdahan, S ; Sharif University of Technology
2012
Abstract
Shared hosting is a kind of web hosting in which multiple websites reside on one webserver. It is cost-effective and makes the administration easier for websites' owners. However, shared hosting has some performance and security issues. In default shared hosting configuration, all websites' scripts are executed under the webserver's user account regardless of their owners. Therefore, a website is able to access other websites' resources. This security problem arises from lack of proper isolation between different websites hosted on the same webserver. In this survey, we have examined different methods for handling mentioned security issue. Also we evaluated the performance of mentioned...
The behaviour of an artificially cemented sandy gravel
, Article Geotechnical and Geological Engineering ; Volume 23, Issue 5 , 2005 , Pages 537-560 ; 09603182 (ISSN) ; Hosseini, S. M ; Toll, D. G ; Yasrebi, S. S ; Sharif University of Technology
2005
Abstract
The major section of the city of Tehran, Iran has been developed on cemented coarse-grained alluvium. This deposit consists of gravely sand to sandy gravel with some cobbles and is dominantly cemented by carbonaceous materials. In order to understand the mechanical behaviour of this soil, a series of undrained triaxial compression tests and unconfined compression tests were performed on uncemented and artificially cemented samples. Portland cement type I was used as the cementation agent for preparing artificially cemented samples. Uncemented samples and lightly cemented samples (1.5% cement) tested at high confining pressure showed contractive behaviour accompanied with positive excess pore...
Kalman filter based packet loss replacement in presence of additive noise
, Article 2012 25th IEEE Canadian Conference on Electrical and Computer Engineering: Vision for a Greener Future, CCECE 2012 ; 2012 ; 9781467314336 (ISBN) ; Ghorshi, S ; Tahaei, A
2012
Abstract
A major problem in real-time packet-based communication systems, is misrouted or delayed packets which results in degraded perceived voice quality. If packets are not available on time, the packets are considered as lost. The easiest solution in a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system, to avoid degradation in speech quality due to packet loss, a suitable method or algorithm is needed to replace the missing segments of speech. In this paper, we introduce an adaptive filter for replacement of lost speech segment. In this method Kalman filter as a state-space based method will be used to predict the...
An imperialist competitive algorithm approach for multi-objective optimization of direct coupling photovoltaic-electrolyzer systems
, Article International Journal of Hydrogen Energy ; Vol. 39, Issue 33 , 11 November , 2014 , pp. 18743-18757 ; ISSN: 03603199 ; Sayedin, F ; Khavas, S. S
2014
Abstract
In the context of sustainable clean hydrogen production pathways, photovoltaic-electrolyzer systems are one of the most promising alternatives for acquiring hydrogen from renewable energy sources. In fact, determining the optimal set of design and operating variables are always a key issue while coupling directly renewable electricity sources to PEM electrolyzers. Few previous studies have attempted to find the optimal size and operational condition of directly coupled photovoltaic-electrolyzer (PV/El) systems in order to maximize the hydrogen production or to minimize energy transfer loss between photovoltaic devices and the electrolyzer. Nevertheless an easy and efficient approach still...
Investigation of Mesh Sensitivity Influence to Determine Crack Characteristic by Finite Element Methods
, Article Journal of Failure Analysis and Prevention ; Volume 16, Issue 3 , 2016 , Pages 506-512 ; 15477029 (ISSN) ; Mirjavadi, S. S ; Asli, S. A ; Sharif University of Technology
Springer New York LLC
2016
Abstract
In this research, an extended finite element model has been investigated. Investigation of opening and closure stress always has been one of the difficult parameters to analysis of results; therefore, the utilization of finite element methods would be a good and logical alternative for this purpose. In addition, linear elastic fracture criteria are used for validation of numerical results from the simulation. In this work, a detailed analysis of the influence of different parameters in the results of a specific specimen with a semi-elliptical tooling groove in terms of closure and opening stress is presented, and the impact of optimum element size in fracture characteristic in various load...
Investigation of the effect of nanosilica on rheological, thermal, mechanical, structural, and piezoelectric properties of poly(vinylidene fluoride) nanofibers fabricated using an electrospinning technique
, Article Industrial and Engineering Chemistry Research ; Volume 56, Issue 44 , 2017 , Pages 12596-12607 ; 08885885 (ISSN) ; Ahmad Ramazani, S. A ; Talebi, S ; Fattahpour, S ; Hasany, M ; Sharif University of Technology
2017
Abstract
The effects of different nano-SiO2 contents on the rheological properties of poly(vinylidene fluoride) (PVDF) solution and mechanical, thermal, structural, and piezoelectric properties of composite nanofibers were investigated. Results showed an increase in fiber diameter (∼125 to 350 nm) and ∼450% increase in tensile strength as the content of nano-SiO2 particles increased. The degree of crystallinity decreased by 19% as the nano-SiO2 content increased by 2% (w/w). Further investigation demonstrated that silica could significantly improve the piezoelectric properties of PVDF nanofibers as the output voltage showed an increase in the presence of silica attributed to change in the crystalline...